Document pBZ48g2EZB74rkMe0KKZLnm8D

I BFG21767 T0098S# 89Z,IDd9 THE STORY OF THE PLASTICS INDUSTRY The U.S. plastics industry is a multi-billion dollar business--and still growing at a rate faster than most other industries in this country. The 27 billion pounds of plastics it produced in the mid-1970's found use in every major market in the United States: construction, packaging, automobiles and boats, electrical/electronics, pipe and fit tings, and consumer goods, to mention just a few. Plastics are, in fact, a basic material of use--on a par with metals, glass, wood, and paper--and critical to the needs of virtually the entire spectrum of U.S. business. As life styles change, they are becoming ever more critical to to morrow's advanced new concepts in architecture, aerospace, communications, transportation--even medicine and the arts. Yet the materials trace their origin in this country back to only 1868 when a young printer named John Wesley Hyatt came up with Celluloid--the first American plastic. Because of their rapid growth in this rela tively short span of time, compounded by a versatility that has spawned dozens of dif ferent families and types of plastics, each with its own special properties, public awareness of plastics has not kept pace with public interest. This booklet, there fore, has been prepared by The Society of the Plastics Industry, Inc., representing some 1400 member companies who are responsible for about 75% of plastics sales in the U.S., to answer the need. It is intend ed to answer your basic questions about plastics and the plastics industry, what plastics are and where and how they ar^ used, how they can benefit both consumers and industry, and what opportunities they*? represent for businessmen seeking waysdl in which to use plastics or students, techSP nicians, or workers looking for career opy* portunities in this exciting and fast-movincP industry. O CA i BFG21769 L HOW IT ALL BEGAN... AND WHERE IT'S ALL GOING Plastics are the ultimate tribute to man's Plastics are among the best electrical insu-1 creativity and inventiveness. They are true lating materials in the world, but you can > man-made materials. But like any material, also formulate them to actually act as j they have their origins in nature, in such conductors of electricity. Plastics are the j basic chemical elements as carbon, oxy rugged shaft of a golf club, but they're also j gen, hydrogen, nitrogen, chlorine, or sul the flexible upholstery that covers your ! fur that are, in turn, extracted from na chair. They're the impact-resistant trans ture's storehouse of air, water, gas, oil, parent safety glazing in a shower door, but coal, even plant life itself. It was man's they're also the transparent box you buy at inspiration to take these elements and a notions counter to store needles and combine them via various chemical reac thread. tions in an almost unending series of com binations to produce the rich variety of materials we know today as plastics. The number of permutations possible in combining chemical elements to create plastics with different properties is almost i It is possible today to create different plas endless. It is this diversity that has made1 tics from different combinations of ele plastics so applicable to such a broad ments with almost any quality desired in an range of end-uses and products today. end-product--some similar to existing Vet, paradoxically, it is also this diversity conventional materials but with greater that has made it difficult for the layman to economic values, some representing sig grasp the concept of a single family of nificant property improvements over exist materials that can encompass such a far- ing materials, and some that can only be reaching span of properties and character described as unique prime materials with istics. characteristics known to man. unlike any previously WHERE IT BEGAN There are plastics that will melt at 200 F. and others that can go well over 1000 F. The heat shield that protects astronauts travelling in space is based on a concept known as "ablative plastics." There is a "plastic armor" commercial today that can stop a bullet, even shell fragments. There are flexible plastics films that you wrap sandwiches in for a picnic lunch and there are rigid plastics rugged enough to serve as supporting members in a building. Given this kind of versatility and the role that plastics play in modern living, it's surprising to realize that a little over a century ago, there was no such thing as a commercial plastic in the United States. It is true that during the 1850s and 1860s, development work was going on with hard rubbers and cellulose materials that would pave the way for later work in plastics. But the U. S. plastics industry officially dates its beginnings back to 1868 when John Wesley Hyatt mixed pyroxylin, made from cotton (one of nature's polymeries) and nitric acid, with camphor to create an entirely different and new product he called Celluloid--the first commercial plastic in the U.S. The development was in response to a competition sponsored by a manufacturer of billiard balls. It came about when a shortage developed in ivory from which billiard balls weremade and the manufacturer sought another production' method. Celluloid was one of the materi als considered--and the U.S. plastics in- ] Plastics' varied uses range from packaging.... dustry was born. 2 BfG21/7q As has been typical of new plastics materi als ever since then, Celluloid quickly moved into other markets. It is perhaps best remembered as the material from which wipe-clean collars, cuffs, and shirt fronts were made and as the window cur tains on early automobiles. More impor tant, the first photographic film used by Eastman was made of Celluloid to produce the first motion picture film in 1882. The material is still in use today, under its chemical name of cellulose nitrate, for making products like eyeglass frames. Forty-one years were to pass before the plastics industry took its second major step forward. In 1909, Dr. Leo Hendrik Baekeland introduced phenolformaldehyde plastics (or phenolics as they are more popularly known)--the first plastic to achieve world-wide acceptance. More im portantly, he also evolved techniques for controlling and modifying the phenolform- aldehyde reaction so that useful products like marbleized clock bases or electric iron handles could be formed under heat and pressure from the material. This character istic of liquefying the material so it can be formed into various shapes under heat and pressure is still common to most plastics. The third big thrust in plastics develop ment took place in the 1920s with the introduction of cellulose acetate (which was similar in structure to cellulose nitrate but safer in processing and use), ureaformaldehyde (which could be processed like the phenolics but could be molded into light colored articles that were more attractive than the phenolic's blacks and browns), and poly (vinyl chloride) or vinyl or PVC, as it is also called--eventually to become the second largest selling plastic for such applications as flooring, uphol stery, wire and cable insulation, pipe and fittings, and apparel use. Nylon, which you know best as fiber but which the industry also knows as an important industrial ma terial, was developed in the late '20s through the classic research of W. T. Carothers. As is evident in the list on page 5 which gives the year each plastic was introduced and identifies a typical end- product, the tempo of plastics develop ment picked up considerably in the 1930s and the 1940s. Each decade saw the intro duction of newer, more exciting, more versatile plastics. In the 1930s there were acrylic resins for signs and glazing and the ...to outer space. Proposed space shuttle (above) will have a large external fuel tank with an outer insulating skin based on a plas tic material called polyurethane. 3 22586005 BFG21771 commercialization of polystyrene (which compete directly with meta/s. This sub had been familiar to chemists since the group has grown since then to include a > 1830s, but as nothing more than a curios number of new plastics as well as im ity). Polystyrene, of course, was destined proved variations on older plastics that to grow to become the third largest-selling could similarly qualify for inclusion. plastic and to literally revolutionize seg ments of the housewares, toys, and pack aging industries. Melamine resins were also introduced for use in dishware, paints, and wet-strength paper. Although not recognized as such by the consumer, they later became a critical element (in the form of a binder) in the development of The 1960s and 1970s also had their share of new plastic introductions, most notably thermoplastic polyesters (typical uses: ex terior automotive parts, under-the-hood applications, and bottles) and high nitrile barrier resins with the kind of oustanding resistance to gas permeation that made i them applicable for use in packaging. Dur-: decorative laminate kitchen counter tops, table tops, vertical surfacing, and the like. ing this time span, another sub-group of the plastics family also started to form: the In the World War II years of the 1940s, the so-called "high-temperature plastics." In demand for plastics accelerated as did cluding such materials as polyimides, research into new plastics that could aid in polyamide-imides, aromatic polyesters, the defense effort. Polyethylene--today, polyphenylene sulfide, polyether sulfone, the most important plastic in the world-- and the like. These materials historically was a war-time development that grew out had their impetus in meeting the demand of the need for a superior insulating mate ing thermal needs of aerospace and air rial that could be used for applications like craft applications. Today, however, they radar cable. The thermoset polyester res have moved into the commercial areas that ins that only a decade or so later were to require their ability to operate at continu radically change the boat-building busi ous temperatures of 400 F or more (in ness in the United States were also a many cases, these materials can sustain war-time development introduced for mili 1000 F continuous service with 50% reten tary use. And acrylonitrile-butadiene- tion of original mechanical properties). styrene plastics (or ABS)--which you know best today in appliance housings, refrig HOW THE INDUSTRY erator liners, safety helmets, pipe, tele HAS GROWN phone handsets, and luggage--owes its Each of these new plastics--from 1868 up origins to research work emanating from until today--represented a new market the war-time crash program on the large- possibility and each eventually resulted in scale production of synthetic rubber. a significant increase in sales. It took the By the start of the 1950s, plastics were on their way to being accepted by designers and engineers as basic materials along with the more conventional ones. This decade also saw the introduction of polypropylene--following the Nobel Award-winning work of Karl Ziegler in Ger many and Giulio Natta in Italy for "order ing" the molecular arrangement of plas tics. Also highlighting this decade was the development of acetal and polycar bonate-two plastics that, along with ny U. S. plastics industry almost 80 years to reach a one-billion pound production level in the mid-1940s, but only about 20 years after that to grow to 15-billion pounds in 1967, and less than 10 years after that to approach doubling that figure to 29.3 billion pounds in 1974. Polyethylene alone had a production capacity of almost 6.. billion pounds in 1974--which was more j than the entire industry sold in 1959. Andj polyethylene wasn't even introduced to the) marketplace until 1942. lon, came to form the nucleus of a sub Estimates are that by the year 2000, pla: group in the plastics famijy known as the tics materials will have grown 10-fold to "engineering thermoplastics". Their out 225-billion-pound production level in tfo standing impact strength and thermal and United States alone--making it one of tb dimensional stability enabled them to world's most important materials of usej 4 22586006 INTRODUCTION OF PLASTICS MATERIALS DATE MATERIAL TYPICAL USE 1868 CELLULOSE NITRATE EYE GLASS FRAMES 1909 PHENOL-FORMALDEHYDE 1909 COLO MOLDED TELEPHONE HANDSET KNOBS ANO HANDLES 1919 CASEIN KNITTING NEEDLES 1926 ALKYD ELECTRICAL BASES 1926 ANALINE-FORMALDEHYOE TERMINAL BOARDS 1927 CELLULOSE ACETATE TOOTH BRUSHES, PACKAGING 1927 POLYVINYL CHLORIDE RAIN COATS 1929 UREA-FORMALDEHYDE LIGHTING FIXTURES 1935 ETHYL CELLULOSE FLASHLIGHT CASES 1936 ACRYLIC BRUSH BACKS. DISPLAYS 1936 POLYVINYL ACETATE FLASH BULB LINING 1938 CELLULOSE ACETATE BUTYRATE IRRIGATION PIPE 1938 POLYSTYRENE OR STYRENE KITCHEN HOUSEWARES 1938 NYLON (POLYAMIDE) GEARS 1938 POLYVINYLACETAL SAFETY GLASS INTERLAYER 1939 POLYVINYLIDENE CHLORIDE AUTO SEAT COVERS 1939 MELAMINE-FORMALDEHYDE TABLEWARE 1942 POLYESTER BOAT HULLS 1942 POLYETHYLENE SQUEEZABLE BOTTLES 1943 FLUOROCARBON INDUSTRIAL GASKETS 1943 SILICONE MOTOR INSULATION 1945 CELLULOSE PROPIONATE AUTOMATIC PENS ANO PENCILS 1947 EPOXY TOOLS ANO JIGS 1948 ACRYLONITRILE-BUTADIENE-STYRENE LUGGAGE 1949 ALLYLIC ELECTRICAL CONNECTORS 1954 POLYURETHANE OR URETHANE FOAM CUSHIONS 1956 ACETAL AUTOMOTIVE PARTS 1957 POLYPROPYLENE SAFETY HELMETS 1957 POLYCARBONATE APPLIANCE PARTS 1959. CHLORINATED POLYETHER VALVES AND FITTINGS 1962 PHENOXY BOTTLES 1962 POLYALLOMER TYPEWRITER CASES 1964 IONOMER SKIN PACKAGES 1964 POLYPHENYLENE OXIDE BATTERY CASES 1964 POLYIMIDE BEARINGS 1964 ETHYLENE-VINYL ACETATE HEAVY GAUGE FLEXIBLE SHEETING 1965 PARYLENE INSULATING COATINGS 1965 POLYSULFONE ELECTRICAL/ELECTRONIC PARTS 1970 THERMOPLASTIC POLYESTER ELECTRICAL/ELECTRONIC PARTS 1973 POLYBUTYLENE PIPING 1975 NITRILE BARRIER RESINS CONTAINERS Z0998SZZ 5 BFG21773 BFG21774 PLASTICS-PARTNER IN TODAY'S LIVING Plastics are already one of the more impor plastics--cellulose nitrate solutions on tant materials of use--taking their place in glider wings and on the wings of the plane commerce along with metals, glass, wood, in which they made their historic flight in and paper. One would be hard put to find a 1903). market in the United States today into which plastics, either by themselves or in combination with other materials, do not play a vital role. One would be hard put to visualize a world offering similar comfort and convenience that did not include plas tics. There are plastics uses that go unrecog nized because they show up in combina tion with other materials. All "paper" car tons for milk have protective coatings of polyethylene, many metal cans have pro tective plastics linings, many glass bottles have protective plastics coverings. So- Because of the diversity of plastics, many of their uses still go unrecognized. Every consumer certainly is aware of plastics in the form of housewares, toys, appliance parts, knobs, handles, electrical fixtures, called "decorative laminates" for counter and table tops are based on liquid plastics as a binder and surfacing material com bined with layers of paper and com pressed under heat and pressure. toothbrushes, cups and lids, packages, There are other plastics uses that go un and household detergent bottles. recognized because of the similar appear But few are aware that the lifelines of all ance of the plastics to other materials-- communications--television, radio, tele such as plastics outerwear apparel with phone, radar, sonar, telstar--are based the gloss of leather or plastics furniture on plastics for insulation and other vital with integral wood grain patterns or plastic components automotive grilles that can be electroplat ed with a metallic surface. . . . that plastics provided the material needed to develop the automobile ignition system and that the average car in the There are still other plastics uses that go unrecognized because they are essentially hidden in the finished product, like the mid-1970s contained over 160 pounds of plastics. including those plastics that have myriad uses of plastics for electrical insu lation or the use of urethane foam as helped Detroit meet exacting new safety thermal insulation in refrigerators--a con standards cept that has given you more food-storing . .. that plastics foams changed modern- capacity without increasing the outside day concepts of cushioning and insulation dimensions of your refrigerator. There are ... that plastics played key roles in the miniaturization and printed circuitry con cepts that revamped the entire electrical/ not many people who know that all U.S. automotive windshields contain a plastic interliner which greatly improves safety. electronics industry in the 1950s But one thing is certain. Plastics do con tribute much to the way in which we live, ... that plastics are essential to modern- work, and play. And the end is not yet in day prosthetics and to the life-saving con sight. Hundreds of millions of dollars con cept of replacing defective heart valves, tinue to be spent by the industry each year ^sockets and joints, and other parts of the in the development of new plastics or the human body with plastic parts improvement of existing plastics. The in ... that most of the domes that cover dustry's technology is now at a point modern-day sports stadiums are a plastic where plastics materials can be tailored to development or that quick-to-erect plas meet the specific demands of special ap tics shelters have helped thousands of plications. victims of earthquakes, floods, or other No matter how our society may change in disasters the future, no matter what transitions we ... or that in aerospace and aircraft, plas may see in our life styles, chances are that tics contributed to the pioneering flights of the fertile mind of man will be able to Alcock and Brown, Lindbergh, Byrd, Shep formulate a plastic that will make those ard, and Glenn (it is even said that the changes and transitions just that much Wright Brothers in the '80s used easier to accomplish. 7 22386009 BFG21775 L THE STRUCTURE OF THE PLASTICS INDUSTRY Today, a minimum of 6,000 companies in j the United States make plastics theirii business--that is, they produce basic ma terials or they process or fabricate plastics into products or parts or they finish these goods in some way by decorating or other means. The number of companies that are customers for these materials and services or that use plastics in one way or another number well into the tens of thousands. Sometimes there is an overlapping of functions between industry and market (e.g., customer companies like automotive and packaging are themselves among the world's largest processors of plastics into products and parts), just as there is an overlapping of functions within the indus try itself (e.g., materials manufacturers may also do processing and finishing). Basically, however, the structure of the plastics industry breaks down along the following lines: PLASTICS MATERIALS MANUFACTURERS These manufacturers or suppliers use chemical reactions to transform basic feedstocks (usually called monomers and derived from gas, oil, etc.) into plastics materials (or polymers or resin, as they are also called). These materials are then sold in the form of granules, powder, pellets, flake, or liquids for eventual processing into finished products. MANUFACTURERS OF CHEMICALS, ADDITIVES, MODIFIERS Between the polymer which the materials manufacturer offers and the finished com pound that goes to the processor, there is often an intermediate step that involves the addition of modifiers, chemicals, and additives which serve to impart special properties to the plastic or upgrade exist ing ones. For example, plastics can be integrally colored (with pigments or dyes) or made more flexible (with plasticizers) or more resistant to light and heat (with stabi lizers) or even stronger and more impact resistant (with fiber reinforcements). The companies that supply these modifiers are often the materials manufacturers them selves; in other instances, they are sepa rate companies specializing in the produc tion of one or more specific types of modifiers for plastics. ^ _ 2258^^53-0 b?g^116 COMPOUNDING/ FORMULATING Again, the compounding or formulating of In more specific terms, plastics processors are classified according to the type of processing they do, as follows: the base resin (through the addition of the MOLDERS produce finished products by modifiers described above) into the fin forcing melted plastic (in its molten state) ished plastic material that goes to the into a mold of the desired shape where it processor is usually performed by the ma cools and is ejected as a finished piece. terials manufacturer. However, there is a They are further sub-classified by the type group within the plastics industry that will buy the base polymer from the materials of molding they do: conventional injection molding, structural foam molding, reac manufacturer and then specially com tion injection molding, compression/ pound it (e.g., add color, modifiers, addi transfer molding, blow molding, etc. tives, etc.) for re-sale to the processor. EXTRUDERS generally produce a continu They are known as compounders. It is also ous shape by forcing melted plastic possible for the processor to buy base through a shaping die, then cooling it so polymers, modifiers, and additives directly that it solidifies into such products as film, and do his own compounding. sheet, rod, tube, pipe, wire covering, paper THE PROCESSOR coating, heavy monofilaments, or thread like filaments that can be woven into fab The plastics processor is at the heart of the rics for upholstery, screening, etc. industry. It is his function to turn the plas CALENDERING is another technique for tics material into secondary products (e.g., producing film and sheeting by squeezing film, sheet, rod, tube, etc.), component plastics down between heated metal rolls. parts, or finished end-products. In general terms, processors are classified according CASTERS work with liquid systems that to whether they are doing the processing on a custom basis for end-users ("custom processors"), or whether they are manu facturing plastics products, like say housewares or toys, for direct sale to consumers ("proprietary processors"), or whether they represent captive (in-house) produc they pour into molds where they set up into either solid or foamed parts that dupli cate the contours of the mold cavity. Cast ing can also be used to produce film and sheet. An offshoot of the casting business is the potting and encapsulation of electri cal/electronic components. tion facilities for manufacturers who use HIGH-PRESSURE LAMINATORS form plastics parts in large volume ("captive sheets, rods, and tubes from paper, cloth, processors"). Again, functions often over glass and wood that have been impregna lap. Many custom processors also carry ted with resin solutions, then subjected to proprietary plastics lines. heat and pressure. 22586011 Typical chemical plant for transform ing a gaseous monomer Into the finished plastic material... ...which is then granulated or pellet ized into a free-flowing form to be shipped to processors. 9 BFG21777 COATERS make use of various coating Fabricators can work with conventional techniques (spread coating, dip coating, machine tools and simple bending tech etc.) to coat such substrates as fabric, niques to convert rigid plastics shapes into metal, and paper with plastics. Since both industrial parts, jewelry, signs, furniture, extrusion and calendering methods can etc., or they can work with various die also be used for coating, there is some cutting and sealing methods to turn flexi overlap between the three classifications. ble film and sheeting into shower curtains, REINFORCED PLASTICS MANUFACTUR ING applies to the production of products rainwear, inflatables, upholstery, packag ing overwrap. based on plastics resins that have been A very special category in the fabricating combined with such fiber reinforcements area involves the thermoforming as glass, graphite, synthetics, etc. There process--that is, shaping heated plastic are many processing techniques unique to film or sheet over or into a mold by either these manufacturers (e.g., hand lay-up, pulling a vacuum or applying pressure in filament winding, autoclave molding, etc.), various ways. This process is used for but it is also possible to use many of the making skin or blister packages, signs, more conventional molding or fabrication boat hulls, sinks and basins, even entire methods described in this section to pro modular bathroom units. A more recent duce reinforced plastics parts. offshoot of the process is known as stamp ing or forging. These techniques require FOAMED PLASTICS PROCESSING also considerably less heat and are applicable cuts across many of the processing classi to modified metal stamping equipment. fications listed above. While there are again some techniques unique to plastics FINISHING THE foams (e.g., pour-in-place, frothing, slab stock manufacturing), many processors PRODUCT who mold, cast, extrude, calender, or coat Finishing, decorating, and assembly of the can, and have, worked with plastics foams. plastics end-product can either be done in-house by the plastics processor or fabri cator or can be sent to companies that may THE FABRICATOR specialize in various finishing techniques. Such a specialty might be the metallizing In industry terminology, the fabricator's of plastics products like shower heads or role is to turn secondary products such as car door handles to give them a chrome film, sheet, rod, tubes, and special shapes like appearance or the large-volume print into end-products. ing of plastics film and sheet. At the processor's shop, skilled moldmaker works on a mold for producing plastics parts for toy model kit jshown at left of mold). 10 Last stop for a plastic part Is the finishing operation. Here, a wood grain-printed foil Is being applied to a polystyrene TV housing. 22586012 BFG21778 BpG2l779 I As man-made materials, plastics were cre point in its life when a product went into ated to meet specific needs of society, to use and was then discarded--the genera do specific jobs. When medical men tion of solid waste in the form of house sought a unique material that could be hold rubbish, trash and garbage. The is used for replacing parts of the human sues concerning plastics centered on their body, and which would be non-toxic and role in litter, in incineration, in landfill and would not degrade or decompose, they in recycling. found it in plastics. In the automobile in dustry, the light weight of plastics has been a major key to fuel conservation, just as their impact resistance and flexibility have contributed to safety. In the packag ing industry, the durability and versatility Some of the issues have since been found >j to have little substance, while others are i still being debated. In the "littering" issue, | for example, there is fairly general agree- i ment that this is a "people" problem andl of plastics helped usher in a new era of convenience and safety that has markedly changed the way we buy and use pack aged goods. not a "materials" problem. The issue r arises more from the disposable nature of 1 some products than it does from the mate rials used for the products (e.g., plastics i and glass bottles, metal cans, newspapers, The list of such developments is extensive, paper cartons, etc.). including, more recently, the utilization of plastics' unique resistance to corrosion in the design of modern pollution con trol equipment, and the use of its thermal insulating properties to help reduce home heating requirements and conserve energy. In the "problem" of incineration, modem | technology has made it clear that in an efficiently operated incinerator there is lit-jjj tie problem with the gases, smoke or soot s from any material, including plastics. In a$i substandard incinerator, there can be^j problems with many materials, again in-1 Yet, in the 1960s and early 1970s when eluding plastics but also including food a environmental concerns mounted, some waste, paper etc. of the characteristics of plastics that had been considered desirable were turned 180 degrees and listed as detrimental. In sanitary landfill, where waste is corn-til pacted and covered with soil for eventual |r First, there was some concern about the manufacturing process itself, as there was recovery and reuse of the land, the resist- ance of various plastics to degradation has at that time for all manufacturing indus been labeled by various groups as a disad-. tries. But steps were quickly taken to meet vantage. This characteristic is one of the existing standards and regulations. very reasons, of course, why plastics are used in so many applications. And there However, the major environmental con are many sanitation officials who feel that cerns about plastics related more to the nondegradable plastics make a very stable material for landfills because they do not break down and pollute the water table with decaying matter or chemical residues, nor do they continue to settle over the years. A landfill with a heavy proportion of plastics in it could thus be quickly turned into reclaimed land. This debate on "bio- degradability" continues. In recycling, the problem does not lie with the ability of plastics to be recycled. That is relatively easy to do, simply by grinding the plastic product down to a pellet form ` can then be fob directly back into a pr essing machirife to make another pro*' The major problem arises, instead, in arating the. many diverse plastics non-plastics materials out of a waste stream so that each can be. The economics have-not supported/! 12 t 22586014 "1 BFG21781 public awareness that plastics largely de tics reduces energy consumption in the. rive from petrochemicals which are prod shipping and distribution of products.! ucts of gas and oil refining. However, the Most products based on plastics also use! use of energy by plastics was blown far out less material by weight than if they werej of proportion. based on nonplastics. At the record heights of production in the mid-1970s, petrochemicals (including those used for the manufacture of synthet THE ROLE OF PLASTICS ic fibers, antifreeze and other products as Plastics constitute a family of materials,! well as plastics) never took more than four each with its own distinctive characteris percent of the total oil barrel. tics, and neither industry nor the public! should take an "all or nothing" view on| An analogy to this overemphasis by the their role in society. In terms of environ-i public upon the role of plastics can be ment, health and energy, they are neither! drawn from the issue of solid waste. At the the perfect material nor the worst material. height of the public outcry in the mid- On one hand, plastics are increasingly^ 1960s against plastics in the solid waste contributing to our enjoyment of life andjjH stream (described above), plastics actually leisure in a way no other material has done* accounted for less than one percent of the before and there are many plastics that are ) 360 million tons of municipal refuse then totally sound in terms of environment and M being generated from household, com health. Yet it is also true that some plastics ^ mercial and industrial sources. (as in any family of materials) have limita-K The question of how much energy is used in making plastics also has been misun derstood. In total energy consumption (manufacturing materials, converting them tions that must be taken into account, and can be taken into account, to make sure that their use proceeds along safe and beneficial lines. | into products, using the products, and There is much the public still has to learn ^ then disposing of them), plastics use less about plastics. The image of plastics as energy than some prominent, competitive "synthetic" or "unnatural" or "cheap" is ' materials... even when we include the energy value of the petrochemical feed stock used to make the plastic. In part, this drawn from an industry that existed some time around World War II--and is long since gone! The concept of "plastics" as a ; ? derives from the tact that the actual manu single, all-encompassing description of a facturing operations for plastics and plas tics products use relatively little energy compared to other materials. Another con tributing factor: the lighter weight of plas material never really existed in fact, al though it existed in the minds of many. Plastics are a family--a broad and diverse family--of different materials. An environ mental problem raised by one plastic can not be arbitrarily extended to all plastics, nor conversely can the characteristics of one plastic that may be sound for the envi ronment and health be extended to all. As the industry continues to develop and refine the ways in which it makes and uses plastics, it is committed to safeguarding the environment and public health, while it j promotes exciting, new, and worthwhile , applications. Thanks to the diligence of our own scientists and technologists, the j interest of government agencies which] monitor us, and the concern of the publicj which depends on us, society will continu to benefit from the improved quality of Irjj that plastics and other materials can brii] At the same time, we can preserve^ environment, safeguard our health,') conserve our energy. 14 22586016 BFG21782 ALL ABOUT PLASTICS To understand plastics, one must first ap supermarkets use shopping bags based on preciate and accept the polymer chemist's high-density polyethylene film. ability to literally re-arrange the molecular structure of the plastic or polymer to pro vide an almost infinite variety of composi tions that differ in form, appearance, prop erties, and characteristics. Finally, to fully understand plastics, one must be aware of the many different routes that the starting materials for plastics can take on the way to consumer or industry. In this brochure, we are concerned primarily One must also approach the subject with a with those resins (or polymers) that are completely open mind that will accept all supplied to the processor in the form of the contradictions that make it so difficult granules, powder, pellets, flake, or liquids to pin common labels on the different and are transformed by him into solid or families of plastics--or even on the various cellular plastics products, shapes, film or types within a single family. In the family of sheeting, or coatings and surfaces for vari polyethylenes, for example, consumers are ous substrates. However, the same starting most aware of the so-called low-density materials used to make these resins can polyethylenes, which are flexible materials take another route and end up in the textile most familiar in housewares, toys, trash industry (nylon fibers share common roots bags, film overwraps, and the like. But with a molded nylon gear; acrylic fibers there is another type of polyethylene called share common roots with acrylic sheet for high-density polyethylene that is rigid and glazing; etc.), the paint industry (the alkyd tough enough to be used in the manufac paints you use in your home and the alkyd ture of materials-handling pallets that can resins that are processed into solid prod support thousands of pounds of stacked- ucts for the electrical industry also have up boxes. To compound the confusion much in common), and the adhesives in even more, high-density polyethylene can dustry (the epoxy adhesives that you buy in also be produced in a flexible film form your local hardware store are first cousin with properties quite different from low- to the epoxy resin binders used for indus density polyethylene film. Many of today's trial reinforced plastic products). 22586017 Flow chart shows ethylene's role In the manufacture of polyethylene, polystyrene, and styrene copolymers. 15 BFG21783 Three-dimensional model m Indicates the way In which 1$,-. small molecules link to- gather to form longer mole- t cutes--the basic structure * of moat plastics. The poly mer chemist la capable of changing the arrangement % of the molecules to create w different plastics with dlf- -m. ferent properties. >8 A starting point tor lastics on p. 15 indicates, ethylene monomer (in a gaseous form) can be combined with benzene and further chemically modified to any plastics derive from fractions of pe produce another--and quite unique- troleum or gas that are recovered during monomer called a styrene monomer. the refining process. For example, ethyl When styrene monomer is polymerized, it ene monomer (one of the more important becomes a styrene polymer or polystyrene. r > P> hi 9 m a1 P a fc L f! a f A t c t l ( not the only basic source that is used in making feedstocks for plastics, they are among the most popular and economical Basically, there is a great deal of flexibility in the plastic manufacturing process for in use today. Coal is another excellent source in the manufacturing of feedstocks for plastics and there are other materials--including such unique possi bilities as agricultural oils like castor oil or tung oil derived from plant life--that are also adaptable. creating a wide range of materials. The way in which the small molecules link together into larger molecules and the structural arrangement they take (e.g., packed closely together, or separated by side protrusions or branches) is one deter minant of the properties of the plastic. The length of molecules in the polymer chain is From these basic sources come the feed a second. The type of molecule is a third stocks we call monomers (that is, a small (e.g., substituting methyl groups or ben molecule or, from the prefix 'mono/ a zene rings or chloride atoms for hydrogen single 'mer'). The monomer is then sub atoms; etc.). Polymerizing two or more jected to a chemical reaction known as different monomers together (a process polymerization that causes the small mole known as copolymerization) is a fourth. cules to link together into ever-increasing And incorporating various chemicals or longer molecules. Chemically, the polym additives during or after polymerization is erization reaction has turned the monomer a fifth. Other modifying techniques are in into a polymer (or, from the prefix 'poly,' use and polymer chemists continue to many 'mers'). The transformation from come up with new ones. ) a monomer to polymer may also help you understand why the names of so many plastics materials begin with the prefix Turning the polymer into | 'poly.' Thus, a polymer may be defined as a a product high molecular weight compound which The polymer or plastic resin must next be contains comparatively simple recurring prepared for use by the processor who will units. turn it into a finished product. In some ... Outside of the plastics held, monomers instances, it is possible to use the plastic^ can take different routes to produce a resin as it comes out of the polymerizatioif)|& ' variety of other important products--from reaction. More often, however, it goes.' anti-freeze to fertilizers. Even with through other steps that put it into a forfjji in the plastics field, a single monomer can that can be more easily handled by contribute to the manufacture of a variety processor and more" easily run through of different polymers, each with its own processing equipment The most popular distinctive characteristics. As the chart solid forms for the plastic resin are asv 16,, 22586018 BFG21784 pellets, granules, flake, or powder. In the pounding in, of additives, plasticizers, hands of the processor, these solids are modifiers, colorants, reinforcements, etc.,); generally subjected to heat and pressure, the compound now goes to the proces melted, forced into the desired shape, then sor who has several techniques available allowed to cure and set into a finished to him for turning the resin into a finished product. Plastics resins are also available product or part, into a secondary product as semi-solids (e.g., pastes) or as liquids, (like sheet, rod, tube, shapes, etc.) that for casting. goes through subsequent fabricating op Liquids can also be used to impregnate fibrous materials that can then be allowed to harden into so-called `rein forced plastics'. Another option available to processors is to use resin incorporating a blowing agent. Subjected to the heat of processing or the heat from the chemical reaction, these agents decompose and release gases that can turn a solid product into a foamed erations, or into a coating or surfacing that can be applied to various substrates. At the processing level, plastics can also be turned into monofilaments for use in rope or household screening; or as binders, they are used with materials such as fibers (in "reinforced plastics") or sheets of paper (in "laminates") or sheets of wood (in "plywood") to turn out products like boat hulls, table tops, or airplane wing tips. product (i.e., the gases create bubbles or cells within the plastic that impart a cellu The family of plastics lar construction). There is a generally accepted definition for No matter what direction is taken, howev plastics that goes like this: Any one of a large and varied group of materials con er, it is important in understanding plastics to understand the general flow from basic sisting wholly or in part of combinations of carbon with oxygen, hydrogen, nitrogen, feedstock to end-product--while also ac cepting the fact that there are probably exceptions to the rule all along the way (e.g., some monomers do not have to be polymerized before being processed into an end-product; rather, they can be cast to shape and polymerized in-situ, that is, while the end-product is being shaped). In most cases, however, the flow will proceed and other organic and inorganic elements which, while solid in the finished state, at some stage in its manufacture is made liquid, and thus capable of being formed into various shapes, most usually (al though not necessarily) through the appli cation, either singly or together, of heat and pressure. along these tines: feedstocks, known as Plastics are a family of materials, not a monomers, are polymerized by chemical single material, each member of which has reaction into polymers (or plastics resins); its own distinct and special advantages. the resins are then made into forms useful Whatever their properties or form, howev for processing, sometimes called molding er, most plastics fall into one of two or extrusion compounds (this step can groups--the thermoplastics or the thermo also involve the incorporation, or com sets. 225860109 Thermoplastics materials melt under heat and Thermoset materials solidify under heat and Uquify; on cooling, they solidify--like en ice cannot be made liquid again like a hard- cube. Process can be repeated indefinitely. boiled egg. BFG21285 Thermoplastic resins consist of long mole cules, either linear or branched, having side chains or groups that are not attached to other polymer molecules. Thus,' they can be repeatedly softened and hardened by heating and cooling. Usually, thermo plastic resins are purchased as pellets or granules that are softened by heat under pressure so they can be formed, then cooled so that they harden into the final desired shape. No chemical changes gen erally take place during forming. The anal ogy would be to a block of ice that can be softened (i.e., turned back into a liquid), poured into any shape of cavity, then cooled to become a solid again. In thermosetting resins, reactive portions of the molecules form cross-links between els, food liners, and crispers are based on the long molecules during polymerization. The linear polymer chains are thus bonded polystyrene and ABS--tough, smooth, easy to maintain. together to form a three-dimensional net work. Therefore, once polymerized or hardened, the material cannot be softened by heating without degrading some linkag es. Therfnosets are usually purchased as liquid monomer-polymer mixtures or as a partially polymerized molding compound. In this uncured condition, they can be formed to the finished shape with or with out pressure and polymerized with chemi cals or heat. The analogy in this case would be to a hard-boiled egg that's turned from a liquid (i.e., the yolk) to a solid (the hard-boiled egg) and cannot be converted back to a liquid. Within this framework, we've described below the major plastics materials--both MARINE: Corrosion-resistant, durable rein forced plastics hulls are basic to today's sail thermoplastic and thermoset. Bear in mind boats, power boats, even minesweepers and that these descriptions are intended only ocean-going yachts. to put the various plastics into perspective. None of the actual numbers used or even the word descriptions can be accepted as absolutes. It is just too easy to modify plastics in one way or another (e.g., by reinforcing with fibers or mineral fillers) to turn out a grade that would be quite differ ent from the majority of others that exist under a specific heading. ABS (Acrylonitrile-butadiene* styrene) Thermoplastic. Chemically, this family of plastics are called terpolymers, in that they involve the combination of three different PRINTING: Printing plates made of photo- ^ sensitive polymers herald new era in the more ifft monomers--acrylonitrile, butadiene, and efficient, more economical printing of news- fe styrene--to create a single material that papers. A 18 22586020 BFG21186 draws from the best properties of all three. as a potential replacement for die-cast ABS, which are the initials by which it is metals (especially die-cast zinc and alumi most popularly known by industry and num). They were, in fact, one of the pio consumers, was introduced to the market neers in the concept of "engineering in 1948, primarily as a result of activities thermoplastics"--materials that would that had taken place during the war years offer greater toughness and rigidity. More in the development of synthetic rubbers. important, these plastics were formulated In terms of properties, ABS possesses out standing impact strength and high me chanical strength, which makes it so suit to retain their high level of performance under load and over a wide range of tem peratures and environment. able for tough consumer products. They Industrial end-users are very familiar with have good dimensional stability and good the acetals in the form of gears, bearings, electrical insulating properties. bushings, cams, housings, conveyors, and ABS plastics are available as powder or granules for injection molding, extrusion, and calendering. They can also be blow molded; as sheet, they can be vacuum formed, pressure formed, or even "cold" stamped. Expandable grades are now commercial for producing foamed ABS parts. any number of moving parts in appliances, business machines, etc. Consumers may be more familiar with its uses than they realize. In today's automobile, visible ace tal parts include hardware such as door handles, electrical switches, and seat belt components; in plumbing, there are valves, pumps, sinks, and faucets molded of the acetals; the bodies of lighters, re You may know ABS best as the material in placeable cartridges in shavers, and vari your telephone body or as the inner door ous parts of high-quality toys are often liner in your refrigerator. Safety helmets, based on acetal: and there are even acetal housings for small appliances and busi zippers and gas tank caps. ness machines, instrument clusters and Acetals are extremely rigid without being other automotive parts (including grilles), brittle. They have a high melting point, TV and radio housings, and pipe and pipe high strength, good frictional properties, fittings are also typical uses. In the 1960s, and resistance to fatigue. The long-term ABS found wide outlet as a substrate for stability of parts made from acetals in metallizing (i.e., applying a chrome-like terms of retention of dimensions and metallic finish to the plastic) and appeared strength have been proved over the years. in such products as shower heads, door They are odorless, tasteless, and non handles, faucet handles, and the automo toxic. Acetals are highly resistant to organ tive front grilles mentioned above. Other ic solvents, but are generally not recom applications: valve bodies, toys, tool han mended for contact with strong acids or dles, sailboat hulls, electric cart bodies, strong bases. materials-handling trays and boxes, etc. Acetals are available as compounds for By eliminating the butadiene phase in an injection molding, blow molding, and ex ABS resin, it is possible to create another trusion. Grades reinforced with glass fi type of plastic known as SAN or styrene bers (higher stiffness, lower creep, im acrylonitrile. SAN is known as a copolymer proved dimensional stability) or TFE- since it involves the mixture of only two fluorocarbon fibers (improved frictional monomers--styrene and acrylonitrile--as and wear properties) are also on the mar contrasted to three monomers in the ABS ket for special uses. terpolymer. SAN materials, introduced in the 1950s, are rigid, transparent, and char ACRYLICS & acterized by outstanding chemical re Thermoplastic. These plastics, introduced sistance. Typical applications: automobile in 1936 in the form of hard, rigid, and instrument panels, instrument lenses, tum transparent materials, are well-known vD blers, and housewares. both to industry and to the public, al- ACETAL RESINS though they are often referred to by the tradenames under which they are sold N Thermoplastic. Acetal resins are available rather than by their correct generic title. !* both as homopolymers and copolymers. Major applications are: safety glazing; They were introduced to industry in 1956 lighting diffusers (particularly enclosures 19 BFG21787 for outdoor street lights); aircraft canopies circuit breaker insulation, coil forms, ca and windows; outdoor signs; automobile pacitor and resistor encapsulation, cases, tail lights; escutcheons and nameplates for housings, and switchgear components. appliances; washbasins and sinks; safety shields; TV shields; furniture (e.g., tables); skylights; and food and drug packages (using the new acrylic multipolymers). They are also finding increasing use in the building field in large-area enclosures for shopping centers, swimming pools, res taurants; etc., and as room dividers. Major properties, of course, are in the electrical area where alkyd molding mate rials offer excellent dielectric strength (will resist more than 350 volts per mil), high resistance to electrical leakage, and excel lent arc resistance. Alkyds also have excel lent heat resistance and are dimensionally stable under high temperatures. The acrylics are transformed into end- products in several ways. They are most ALLYLICS widely used in the form of sheets. Products Thermoset. Allylics were developed after can also be cast directly from the liquid World War II. From the plastics standpoint, into molds, although acrylic molding com however, the important innovation came in pounds are available for injection molding, 1949 when diallyl phthafate (DAP), the extrusion, blow molding, and other stan most widely used compound in the allylic dard processing methods. It is further pos family, was introduced for electronic parts, sible to produce acrylic in film form for use electrical connectors, bases, and hous as a protective surfacing over more ings. weather-susceptible plastic sheets. This outstanding resistance to long-term exposure to sunlight and weathering is one of the more important characteristics Two of the most outstanding features of DAP are excellent dimensional stability and a high insulation resistance (5 x 10* megohms) which is retained to an ex of acrylic. Also notable is the exceptional tremely high degree after exposure to clarity and good light transmission it offers moisture. Also: high dielectric strength, (cast acrylic sheet transmits about 92% low dielectric loss, low dielectric constant total light). In crystal-clear .form, acrylics over a wide frequency range, and excellent can pipe light--that is, pick it up at 6ne arc resistance. DAP has a service tempera end and transmit it unseen, even around ture up to 350 F., but another variation in curves. the allylic family, diallyl isophthalate Acrylics are strong, rigid, and more resist (DAIP), can be used at temperatures up to ant to impact than glass. Modified acrylics 450 F. All allylics are highly resistant to and acrylic multipolymers that offer even decomposition by practically all chemicals higher impact strengths and toughness and offer superior resistance to the ad are also now available. However, acrylics verse effect of weathering. are not as resistant to surface scratching as glass, although new surface coatings are being formulated to overcome this limitation. Acrylics have low water absorption, good electrical resistivity, and fair 'tensile strength. Service temperatures range from 120 to 200 F, depending on the load in volved and the grade used. ALKYDS Thermoset. This plastic was developed in 1926 and was promptly put to work in liquid form as enamels, paints, lacquers, and similar coatings for automobiles, re frigerators, stoves, and similar products-- still the largest use for the alkyds. In 1948, however, an alkyd compound was intro A TYPEWRITER BALL molded of phenolic typifies high level of impact resistance In duced as a molding material for compres modern-day applications for various plastics sion molding electrical applications like materia,, ^586022 20 BFG21788 In addition to availability as a molding material, the allylics are used in powder and liquid form as coating and impregna ting materials. CELLULOSICS Thermoplastic. Cellulosics go back to the very start of the plastics industry when John Wesley Hyatt created the first com mercial U. S. plastic, cellulose nitrate, in 1868. Several other important members of the cellulosics family, each with its distinct properties, were introduced in the 1900s. Cellulosics as a group are characterized by good strength, toughness, and high sur face gloss. In addition, they have good GREENHOUSES: Many plastics, including chemical resistance. There are, however, glass-reinforced polyester (above), acrylic, important differences among the various polycarbonate, films, etc., are used in glazing. types. Cellulose acetate. Good toughness and rigidity. Resistant to most household chemicals, oil, gasoline, and cleaning flu ids, but should be kept away from alcohol and alkalies. Unaffected by normal mois ture and moderate heat and will withstand normal usage at below freezing. Forms: molding compounds for injection molding, extrusion, blow molding, etc.; sheets, films, rods, tubes, shapes; coatings. Appli cations: rigid packaging, recording tape, photographic film, knobs, appliance hous ings, handles, toys. Cellulose acetate butyrate. Tougher than acetate and with lower moisture absorp tion. Resists weathering and has excellent ELECTRICAL: Cables and wiring rely on super transparency. Resistant to most household chemicals but adversely affected by alco ior electricals of plastics insulation based on vinyl, polyethylene, fluoroplastics (above), etc. hol, alkalies, paint removers, and ace- i tones. Forms: molding compounds for in jection molding, blow molding, extrusion, etc., sheets, rods, tubes, shapes; coatings (including powder coatings). Applications: tool handles, knobs, dials, appliance hous ings, steering wheels, signs, and light globes. Cellulose propionate. Similar in properties to butyrate, but with somewhat higher tensile strength, modulus, and impact strength. Forms: molding compounds for : injection molding and extrusion; film and : sheet. Applications: automobile arm rests, ; pen and pencil barrels, appliance hous ings, and toys. :i Ethyl cellulose. Excellent toughness and higher impact than other cellulosics. Can AEROSPACE: Largest graphite-epoxy com posite structures made are these 60-ft. long cargo bay doors for the Space Shuttle ij best maintain toughness and resiliency at Orbiter. 21 i BFG21789 sub-zero temperatures. Good dimensional stability over a wide range of temperatures and humidity conditions. Unaffected by alkalies, weak acids, but should be kept away from cleaning fluids, oils, and sol vents. Forms: molding compounds (gran ules or flake); sheet, film, rod, tubes, and shapes. Applications: flashlight housings, tool handles, roller wheels, refrigerator breaker strips. Cellulose nitrate: Available only as sheet, film, rod, and tube, and in solution for coatings, because it is flammable and can not be molded. Offers a wide range of colors and variegated color effects. Appli cations: can be fabricated into decorative and functional products such as personal BUILDING INSULATION: Urethane foam (above) and expanded styrene foam roof In accessories, toilet articles, etc. sulation are builder's newest tools In con serving energy. EPOXY Thermoset. These plastics offer excellent electrical properties and dimensional sta bility, coupled with high strength, low moisture absorption, and superior adhe sive characteristics for bonding metals, plastics, ceramics, glass, hard rubber, etc. Epoxies also have excellent chemical re sistance. Epoxies are used by the plastics industry in several ways. One is in combination with glass fibers (i.e., impregnating fibers with liquid epoxy resins) to produce highstrength composites or reinforced plastics that provide heightened strength, electri cal and chemical properties, and heat re sistance. Typical uses for epoxy-glass re STORAGE TANKS: Huge corrosion-resistant inforced plastics are in aircraft compo reinforced plasties tanks for chemicals can be nents, filament wound rocket motor cas produced at half the.price of stainless steel. ings for missiles, pipes, tanks, pressure vessels, and tooling jigs and fixtures. Epoxies are also used in the encapsulation or casting of various electrical and elec tronic components and in the powder coating of metal substrates. Molding com pounds are also available for transfer and injection molding and most recently, liquid epoxy resins have proven adaptable to a take-off on injection molding known as liquid resin molding. Major outlets for the epoxies would also include adhesives, protective coatings in appliances, indus trial equipment, gymnasium floors, etc., and sealants. FLUOROPLASTICS Thermoplastic. Also known as `fluorocar bons.' Properties of this family, in general, include inertness to most chemicals, re- 22 22586024 BFG21790 sistance to high temperatures, extremely stable at 650 F for short periods of time, low coefficients of friction, and excellent 300 F for longer durations. Applications: dielectric properties which are relatively insulation, seals and gaskets, diaphragms, insensitive to temperature and power fre chemical process equipment. quency. Mechanical properties are nor mally low, but this changes dramatically when the fluoroplastics are reinforced with glass fibers or molybdenum disufide fill ers. Ethylene trifluorethylene (ETFE). Good high temperature and chemical resistance. Can be processed by conventional tech niques. Applications: molded labware, valve liners, electrical connectors, coil There are, however, several members of bobbins. the fluoroplastics family that differ in prop erties and, more markedly, in processing characteristics. This group includes the following: Ethylene chlorotrifuloroethylene (E-CTFE). Strong, highly impact-resistant material that can also be molded or extruded on conventional thermoplastics equipment. Tetrafluoroethylene (TFE). Very heat re Applications: wire and cable coatings (for sistant (up to 500 F), outstanding chemical applications requiring high-performance resistance, and the lowest coefficient of wire), chemically-resistant linings and friction of any plastic. Can be used unlu coatings, molded labware, and film for bricated. Tensile and impact strength are laminates used in aircraft interiors, flexible also good and it has outstanding low tem circuitry and medical packaging. perature characteristics. Processing: TFE cannot be processed by conventional IONOMERS techniques since it does not soften like Thermoplastic. This family of plastics res other thermoplastics; it therefore must be ins was developed in the United States in formed by processes similar to powder 1964. The name 'ionomer' was coined to metallurgy (i.e., powders are compacted to indicate that the polymer contains inor the desired shape and sintered). Applica ganic as well as organic materials linked tions: no-stick coatings for frying pans, by both covalent and ionic bonds. non-lubricated bearings, chemical- Ionomer film is used in the skin packaging resistant pipe and pump parts, high- of a number of products (i.e., the clear film temperature electrical parts, packings, is drawn over the product and a backing gaskets, seals, and rings. board to lock the two together) and as a Chlorotrifluorethylene (CTFE). Heat resist ance up to 390 F,, good tensile strength and impact. Chemically resistant to all in organic corrosive liquids, including oxidiz ing acids and resistant to most organic solvents except certain halogenated mate rials and oxygen-coating compounds (which cause a slight swelling). Process ing: unlike TFE, it can be molded and extruded by conventional processing tech niques. Applications: coil forms, pipe and pump parts, valve diaphragms, fuel sight durable heat-seal layer in composite struc tures (i.e., two or more different films com bined together) used in the vacuum pack aging of processed meat. It is also used in the extrusion coating of foil or paper for food and drug packaging and multi-wall bags. Molded ionomer products include: golf ball covers, top lifts for women's shoes, athletic shoe soles, and bumper guards for automotive exterior trim. In powder form, it can be applied as a protec tive covering for glass bottles. lenses, electrical insulators inserts and lonomers combine transparency with other industrial parts. toughness, especially at low temperatures Fluorinated ethylene-propylene (FEP). This plastic shows the same properties as TFE, but exhibits a melt viscosity low enough to permit it to be molded by ther moplastic processing techniques. Applica tions: wire insulation and jacketing, high- frequency connectors, coils, gaskets, tube sockets. and are more resilient than polyethylene. They are virtually unaffected by oils and greases and are resistant to bases, dilute acids, hydrocarbons, ketones, alcohols, and esters. Resistance to liquid absorption is high by comparison with other plastics of comparable transparency. The ionomers are also distinguished by excellent adhesive characteristics and an ability to Vinylidene fluoride. High tensile strength, be easily sealed to other materials with low cold flow characteristics, thermally heat. 23 22586025 BFG21791 MELAMINES can be molded into products like gears, Thermoset. This plastic is a member of the cams and other sliding contact devices, amino family (which also includes urea) slide fasteners, door hinges, boat propel- and is probably best known to the public lors, and appliance parts or extruded into as colorful, rugged dinnerware. However, film (for packaging and specialty uses it also finds use in many household goods such as "boil-in-the-bag" applications), and in various electrical applications. In sheet, or monofilament for brushes, fish liquid form, it has many applications out ing leaders, printing plates, racket strings, side of the molding area, including adhe and sutures. Nylon can also be blow mold sives, coating resins, and laminating resins ed or rotationally molded. In liquid mono (e.g., decorative laminates for applications mer form, it can be cast into parts that . like counter tops are generally made by polymerize into solids as the part takes $ subjecting melamine resin-impregnated shape. | papers to heat and high pressure). Nylons as a family are characterized by In servicing these markets, melamine res ins offer extreme hardness, excellent col- high tensile strengths, high modulus, and good impact strength. Abrasion resistance orability, and arc-resistant nontracking is high, resistance to heat can go to 250 F, characteristics. Chemical resistance is rel and electrical properties and chemical re atively good, although the material is at sistance are good. tacked by strong acids and alkalies. The The various types of nylon that belong to resins perform satisfactorily over a wide the family are generally labelled according temperature range from as low as--70 F to their molecular structure. Nylon 6, for to as high as 250 (cellulose-or flock-filled) example, derives from the polymerization to 400 F (asbestos- or glass-filled). of caprolactam, a lactam that contains 6 carbon atoms. Nylon 6/6 has a chemical NITRILE BARRIER structure in which both amine and acid RESINS Thermoplastic. This family of resins start segments have 6 carbon atoms. Other types: nylon 8, nylon 11, nylon 12. ed .to appear in the late 1960s and early 1970s. While many of the exact formula tions involved are often the proprietary information of the suppliers and have not been divulged, most are characterized by the inclusion of a high degree of acryloni trile materials. They are called barrier res ins since one of their prime attributes is their resistance to the transmission of gas, aroma, or flavor. They are thus far intend ed primarily for use in packaging. PHENOLIC Thermoset. The second major plastic to be commercialized in the U. S. (in 1909), phenolics are still considered to be the work horse of the thermosetting materials. They are found most commonly in such applica tions as: automotive (distributor caps, ro tors, fuse blocks, and connectors); appli ances (pot handles, knobs, and appliance bases); and electrical/electronic (connec tors, wiring devices, and circuit breakers). NYLONS (POLYAMIDES) Thermoplastic. The nylon fiber industry was born in 1939 when 64 million pairs of nylon stockings were sold--and to this day, most people still associate nylon with fibers. However, in the '40s and '50s work continued on developing nylon com pounds that could be molded and extrud ed or otherwise processed like plastics. Today, the nylons comprise an important member of the plastics family. Actually, there are several different grades that are included under the family name of poly amide resins--each with related but not identical chemical compositions. Most are available in the form of compounds that Chances are most of the electrical switch es in your home are based on phenolic. Like other thermosets, liquid phenolic res ins also find wide outlet as bonding and adhesive resins for abrasives, brake lin ings, insulation, foundry and shell mold ings, and laminates. It is the most popular binder for holding the various plies of wood together in plywood. With the number and variety of types avail able, it is difficult to characterize phenolics as a whole. But, in general, they provide good electrical properties, excellent heat resistance, and good mechanical proper ties, coupled with excellent moldability. They are generally limited in color (usually black or dark brown) and color stability. i 24 22586026 BFG21792 AUTOMOTIVE EXTERIORS: Exciting potential tor plastics: front end panels (shown above, in urethane elastomer), rear ends, grilles, fender extensions, hoods, doors, trunk lids, tops. Car models are already commercial with entire bodies based wholly on plastics materials. LEISURE-TIME PRODUCTS: Molded polypropylene cooler is a familiar product. So are sporting goods like rods, golf clubs, skis, rackets, etc. CONDUIT: Major part of the pipe market is serviced by lightweight polyethylene conduit (above. for a gas and electric powerplant), 25 BFG21793 General-purpose molding grades are usu ally wood-flour and flock-filled. They pro vide a good all-around combination of moderately good mechanical, electrical, and physical properties at low cost. They are generally suitable for use at tempera tures up to 300 F. Impact grades vary with the reinforcement. In order of increasing impact strength, paper, chopped fabric or cord, and glass fibers are used. Glass fiber grades also provide substantial improvements in strength and rigidity. Other popular variations include electrical grades and heat resistant grades (usually mineral- or glass-filled compounds that can take temperatures in the 400 to 500 F range). Special heat resistant phenolics SMALL APPLIANCES: Polypropylene compo nents In automatic coffee makers dramatize (such as the phenyl silanes) provide good fast-growing use of plastics of all kinds in long-term stability at 500 to 550F and appliances. shorter term stability at 600F. Some types are usable for up to 1 hr as high as 1000F. POLYPHENYLENE OXIDE-BASED RESINS Thermoplastic. Introduced in 1964 as part of the family of engineering thermoplas tics, these resins are characterized by out standing dimensional stability at elevated temperatures, broad temperature use range, outstanding hydrolytic stability, and excellent dielectric properties over a wide range of frequencies and temperatures. Stability under long-term loading is out standing. Based on the grades chosen, resistance to heat (continuous) ranges from 175 to 265 F. Temperatures beyond these may be used for occasional short-time exposure. It also resists steam, aqueous chemicals, acids and bases, but will soften or dissolve in many halogenated or aromatic hydro carbons. Molding, extrusion, and foam grades are available. In line with its ability to com pete directly with metals, typical applica tions might include: automotive dash boards, electrical connectors, TV tuners and deflection yoke components, pumps, plumbing fixtures, small appliance and business machine housings, and automo tive trim. ^OLYARYL ETHER Thermoplastic. Polyaryl ether is a highheat engineering thermoplastic distinguished by three important properties: a 26 CONSTRUCTION: Building panels, up to 8 by 24 ft. In size, and based on glass-reinforced plastics, are intended to cover wall surface of 8 building. 22586C28 heat deflection temperature of 300 F, very Polycarbonates are transparent materials high impact strength, and excellent chemi and resistant to a variety of chemicals. cal resistance to organic solvents (except They are, however, attacked by solvents. chlorinated aromatics, esters, and ke Tensile yield strength and impact strength tones). It can be injection molded and is are also quite high. Moisture resistance is recommended for automotive, appliance, low and equilibrium is reached rapidly. and electrical applications. In the automo The materials, however, are adversely af tive industry it can be used for painted fected by weathering (slight color change exterior trim" (since it can take the heats of and slight embrittlement can occur on paint baking ovens) or for under-the-hood exposure to ultra-violet rays). applications requiring outstanding heat resistance. Polycarbonate compounds are available for injection molding, extrusion, blow POLYARYL SULFONE Thermoplastic. This is another high-heat engineering thermoplastic that is charac terized by a very high heat-deflection tem perature (525 F at 264 psi). At normal ambient temperatures, polyaryl sulfone is a strong, stiff, tough material with proper ties comparable to other engineering ther moplastics. Its uniqueness, however, lies in the fact that even at elevated tempera tures, the material can perform without any sacrifice of mechanical or electrical properties. Polyaryl sulfone has good re sistance to a wide variety of chemicals, molding, and rotational molding. Foamable grades for structural foam molding are also being marketed. In < sheet form, polycarbonate is finding use iin safety glaz ing, safety shields, and similar applica tions. Injection molded applications in clude: gears, lenses, electrjcaf relay cov ers, helmets, cams and gears, automotive fender extensions, bezels, telephone switchgear, boat propellors, and housings for hand-held power tools and small appli ances. Blow molded applications being marketed are nursing bottles, milk bottles, and clear containers for bottled water. including acids, bases, and common sol vents. This plastic is designed to meet the need for higher thermal capabilities for aero space, industrial, and consumer use. It can be molded or extruded on conventional equipment, although care must be taken to insure that sufficient pressures and tem perature capabilities are provided. POLYESTERS, AROMATIC Thermoplastic. Introduced in the early 1970's as a high-temperature engineering thermoplastic, this material shows excel lent stability in air at over 600 F and com bines inherent self-lubricating properties with high stiffness, thermal conductivity, electrical insulating properties, and sol POLYCARBONATE Thermoplastic. Polycarbonates were de veloped commercially in 1957 and are one of the pioneering members of the family of engineering thermoplastics created to compete with die-cast metals. vent resistance. Because of its toughness and high heat resistance, it was originally fabricated by metallurgical-type pro cesses. However, an injection moldable version was introduced in 1974. This grade can be processed with conventional equipment. They are among the stronger, tougher, and Typical applications include: self-lubri more rigid thermoplastics. In addition, cating bearings; seals, rotors, or vanes of they have a ductility normally associated process pumps; high temperature circuit with the softer, lower-modulus thermo boards; insulation components; encapsu plastics. lation of diodes, transistors, and integrat These properties, together with excellent ed circuits, and handles and slip-free coat electrical insulating characteristics, are ings for frying pans. maintained over a wide range of tempera tures (-60 to 279F) and loading rates. POLYESTERS, Although there may be a loss of toughness THERMOPLASTIC with heat aging, the material still remains Thermoplastic. Although this material is stronger than many thermoplastics. The also called a polyester, as above, and is creep resistance of these materials is one also a thermoplastic, as are the aromatic of the best for thermoplastics. polyesters described above, in chemical 27 22586029 BFG21795 structure and properties it is quite differ mutated to be brittle and hard, tough and ent. In the form of film, the thermoplastic resilient, or soft and flexible. In combina polyesters were introduced in 1962 for tion with a reinforcement like glass fibers, such applications as photography (micro they offer outstanding strength, a high film, X-ray film); magnetic tape (audio, strength-to-weight ratio, chemical resist video, computer); packaging; metallized ance, and other excellent mechanicals. film; and various tapes and labels. As molding and extrusion compounds intro duced in the early 1970s, they quickly became important new members of the family of engineering thermoplastics. Although polyesters are finding a growing market as a liquid resin for casting furni ture parts (e.g., simulated wood doors, drawer fronts, lamp bases, waif plaques, etc.) their prime outlet is in combination As molding materials, these linear polyes with glass fibers in high-strength compos ters are highly crystalline, with a melting ites (or "reinforced plastics"). Using vari point near 435 F. They are hard, strong, ous lay-up, spray-up, and matched metal and extremely tough. Other characteristics molding techniques, polyester-glass is include: high resistance to abrasion, a low being used for such products as automo coefficient of friction, high resistance to tive body parts, boat hulls, building panels, cold flow, good chemical resistance, good housings, bathroom components, tote dielectric properties, and low moisture boxes, appliances, and electronic and absorption. Thermoplastic polyesters can electrical applications. be extruded, injection molded, or blow Special equipment is also available to in molded. jection mold polyester-glass formulations. Applications include: gears, bearings, Most recently, one-component molding housings for pumps and appliances, im systems, combining resin, reinforcement, pellers, pulleys, switch parts, furniture, and other additives, have been made avail fender extensions, and other products in able to molders. These materials, known competition with metafs or high- as SMC (sheet molding compounds) are performance plastics. The resin is also easy to handle and are adaptable to auto recommended for packaging applications, mated processing. especially for products (i.e., food and med Another popular technique of molding in ical goods) that are to be sterilized by volves premix compounds, which are radiation. It is also being used for blow dough-like materials prepared by combin molded carbonated beverage bottles. ing polyester, glass, catalyst, etc. prior to POLYESTERS, molding. This technique is currently being used to make automotive heater housings UNSATURATED and air conditioner components. Thermoset. Again, while this family of plas tics also go under the name of 'polyesters,' they are quite distinct from the polyesters described above. In fact, they are thermo sets, as opposed to thermoplastics, and are probably most familiar to the public for their role in "reinforced plastics." These materials were introduced for mili tary use (i.e., naval craft) in 1942. After World War II, their characteristics proved extremely appealing to such non-military markets as automotive, marine, corrosionresistant structures, building, electrical applications, and such consumer goods as luggage, fishing poles, and cases and housings of every type and description. Polyester resin is a difficult plastic to de fine since it is so extremely versatile in MEDICAL: Clarity, non-toxicity, sterilizability, terms of the forms in which it finds use in stability--all combine to promote plastics for the industry. Polyester resins can be for- medical devices, like this chest drainage unit. 28 22586030 BFG21796 Also available for use with polyester resins is an extrusion-like technique known as pultrusion in which glass fibers are pulled through a resin bath to make continuous profiles, pipe, or other shapes. into materials handling pallets, stadium seating, trash and garbage cans, automo tive parts. High-density polyethylene film is used in shopping and merchandising bags. POLYETHYLENE Other members of the polyethylene family Thermoplastic. This plastic came to the fore during the World War II years, first as an underwater cable coating, then as a critical insulating material for such vital military applications as radar cable. It was not until the end of the war that the plastic was taken off allocation and freed for con sumer use. From that point on, its rise in popularity for both consumer and industri al uses was so spectacular that polyethyl ene became the first plastic in the U. S. to sell more than 1 billion pounds a year. Today, it is the largest volume plastic in the United States; in fact, it is the largest in the world. include; cross-linked polyethylene--a spe cial grade that's treated either chemically or by irradiation to turn polyethylene, which is a thermoplastic material, into what is essentially an infusible thermoset ting material with outstanding heat resist ance and strength; and high-molecularweight polyethylene, which has extremely high impact strength, excellent low tem perature properties, and outstanding wear and abrasion resistance. To give you some idea of how tough this high-molecularweight material is, it is used as the guide rail for ball returns in a bowling alley--an application in which it can outwear many other materials, including some exotic Again, although the public is most familiar metals. with the so-called "low-density" polyethyl ene in such forms as film for packaging, trash bags, garment bags, etc., and mold ed housewares, toys, containers, and the like, the polyethylene family encompasses a number of different materials with widely varying properties. As indicated, polyethylene is adaptable to most thermoplastic processing tech niques. It can be extruded (into film, sheet, pipe, profiles, etc.), extrusion coated onto many substrates (like paper for milk car tons, foils for packages, etc.), injection molded, blow molded, roationally molded, In general, polyethylenes are character etc. A powdered form of PE is available for ized by toughness, near-zero moisture ab use as a textile impregnant or as a protec sorption, excellent chemical resistance, tive coating for glass bottles. Flexible poly excellent electrical insulating properties, ethylene foam (for electrical insulation) low coefficient of friction, and ease of and rigid PE foam (for protective packag processing. ing) are also on the market. The low-density polyethylenes were the first member of the family to be developed and still dominate in terms of volume sales. These plastics are flexible, with high impact strength and relatively low heat resistance (140 to 175 F, although special grades can go up td~200 F). In the 1950's, polymer chemists developed techniques for providing polyethylenes with higher densities (by packing molecules more closely together). These new variations, appropriately called "high-density" poly ethylene, showed greater stiffness and rigidity as compared to low-density, im proved heat resistance, and increased re sistance to permeability. High-density polyethylene's major use is in blow molded bottles for bleaches, liquid detergents, milk, and other beverages. It can also be blow molded into automotive gas tanks, drums, and carboys, or injection molded MATERIALS HANDLING: Palletized containers thermoformed of ABS sheet, are rigid and tough enough to handle rigors of shipping and storage. 29 22586031 I ! /I ' 1 I JJU BFG21797 L POLYIMIDES One of the newer plastics materials, the polyimides were introduced in the 1960s. They are unique in that, like the polyesters, there is one type of polyimide that acts like a thermoset (in that it exhibits no distinct softening point below its thermal degrada tion temperature) and one that acts like a thermoplastic (in that it softens and can be processed on conventional equipment). The thermoset-type polyimides were the first members of the family to be intro duced. They are among some of the most heat-resistant plastics known and can take temperatures up to 500 F and above for several thousand hours and intermittently HOME EXTERIORS: Polystyrene shutters that at temperatures as high as 900 F. They also can take punishment, weathering, and aging have very good electricals, excellent fric tional characteristics, very good wear re join products in exteriors. like vinyl siding and gutters sistance, superior dimensional stability and excellent bearing qualities. Because of their thermosetting qualities, they can not be processed by conventional tech niques and must use other systems, such as powder-metallurgical methods. They are, therefore, more generally not supplied as compounds for processing, but instead are made available to end-users in the form of finished precision parts, as wire enamels, laminates, adhesives, and film (insulation for electric motor, aircraft wire cable, etc.). Typical applications for poly imide parts: gears, covers, bushings, turbo-fan engine backing rings, insulators, washers, etc., for such industries as air PIPE- Large-diameter pipes in reinforced plas craft and aerospace, nuclear power, office tics or polyethylene open new opportunities In equipment, and electrical/electronics. chemical plants and sewage and water treat ment systems. In the early 1970s, thermoplastic polyim ides were introduced that were process- ible by standard processing techniques such as molding, film casting, solution fiber spinning. Temperature resistance is obviously not as high as for the thermoset-type materials, but still higher than most thermoplastics. Molding com pounds are used for parts like piston rings, valve seats, bearings, seals, and structural components. The resin in solution form is also used as a laminating varnish. POLYPHENYLENE SULFIDE Thermoplastic. Polyphenylene sulfide is another one of those new plastics catego rized as high-temperature, high-strength engineering thermoplastics. It offers out ELECTRICAL USES IN THE HOME: Face plates, covers, and receptacles of polycar bonate (above) or other plastic are among the standing chemical resistance, high stiff30 liar uses. 22588032 BFG21798 J ness, and good retention of mechanical properties at elevated-temperatures. Melt ing point is 550 F. It is resistant to a broad range of solvents, mineral and organic acids, and alkalies. Polyphenylene sulfide is available as com pounds for injection molding or compres sion molding into hard, stiff, strong, and temperature-resistant parts such as valves, pump housings, pump impellers, conveyor rollers, spur gears, etc. It is also marketed in different grades suitable for slurry coat ing, fluidized bed coating, electrostatic spraying, etc. Corrosion-resistant, ther- mally-stable protective coatings based on this resin go into oil-field pipe, valves, fittings, couplings, and other equipment for the petroleum and chemical process PLUMBING: Having made basins, pipe, toilet floats, a mark In sinks, etc., plastics are ing industries. It is also used as a release now moving in on faucets (molded of acetal). coating for molds, cookware, and industri al containers. POLYPROPYLENE Thermoplastic. Polypropylene was devel oped out of the Nobel award-winning work of Karl Ziegler and Professor Natta in Eu rope and came to the United States in 1957. It belong to the olefins family, which also includes the polyethylenes, but it is quite different in properties. It has a low density, is fairly rigid, has a heat distortion temper ature of 150 to 200 F., and excellent chemi cal resistance (like all polyolefins). Poly propylenes also have negligible water absorption, excellent electrical properties, and are easy to process. The ability to carry light loads for long periods and over wide temperature ranges is an important characteristic. Polypropylenes do not have outstanding long-term creep resistance, but fatigue endurance limits are excellent and impart superior flex properties to the material. PACKAGING: Pick any section of the super market and you'll find plastics. Typical: film overwrap and formed trays for meat. In common with the polyethylenes, poly propylene is readily processed by all con ventional systems, including solid and foam molding, extrusion, rotational mold ing, powder coating, and thermoforming. Considerable work has also gone into solid-phase forming of polypropylene, which is similar to the "cold" stamping of metals. Another processing system of im portance to the polypropylenes is known as orientation (i.e., stretching the plastic to align the molecules and impart superior toughness); it is applicable to film, fibers. GLAZING: Lightweight and tough, transparent plastics panels meet stringent regulations on safety glazing for various rooms in the house. 31 22586033 BFG21799 and blow molded products. Polypropylene cartons), in hot and cold insulated drink foam is also available. cups, in marine applications, toys, dis As far as end-uses are concerned, polypro plays, and housewares. pylene is a most versatile material. Con As a family, polystyrenes are characterized sumers are familiar with such molded by hardness, excellent dielectric proper polypropylene products as bottles for syr ties, and ease of processing. Products ups and other foods, closures, automotive made of most polystyrene grades hold parts (fender skirts, battery cases, fan their dimensions well under conditions of shrouds), appliances (agitators in washing normal use, but should not be exposed to machines), toys, housewares, etc. Polypro continued outdoor use. Most foods, drinks pylene foams are also being molded into and usual household acids, oils, alcohol, furniture frames. vinegar, have no effect on polystyrene, but Polypropylene can be extruded into fibers the general run of polystyrenes are affect and filaments for carpets and rugs, carpet ed by citrus fruit rind oil, cleaning fluids, backing, woven bags, and cordage. In the gasoline, turpentine and nail polish and form of film and sheeting, it's the overwrap remover. for cigarettes, records, toys, and house- However, it is difficult to characterize poly wares items. Pipe and profiles, wire and styrenes since one of their advantages is cable coatings, and other extrusions (in that they can be tailored to provide a wide cluding such unusual prdducts as corru range of mechanical, thermal, and chemi gated polypropylene sheet that competes cal properties. directly with traditional corrugated paper board, especially in the packaging of food) round out the list of applications. At the low end of the scale are the general-purpose polystyrenes--trans parent materials with the lowest impacts in POLYSTYRENE the family, but with lower costs and good Thermoplastic. Stryrene monomer and the hardness and rigidity. At the upper end are polystyrene resin made from the monomer the high-impact and extra-high-impact remained as chemical curiosities for 80 polystyrenes which, as their name implies, years following their discovery in 1845. It are opaque materials that offer high im wasn't until 1925 when commercial pro pact, rigidity, and toughness. In-between duction of styrene monomer began in Ger are special grades of polystyreneformulat- many and the U. S. that polystyrene at ed to be light stable (for use in lighting tracted interest, and it wasn't until after fixtures, diffusers, etc.), or more heatWorld War II when monomer capacity resistant or more chemically resistant. could be diverted from its essential war Molded applications for the various poly time use for styrene-butadiene synthetic styrenes include: toys, automotive parts, rubber that polystyrene became an impor housewares, kitchen items, appliances, tant plastic. wall tiles, refrigerator food containers, Today, polystyrene is the third largest vol radio and TV housings, small appliance ume plastic and certainly one of the two or housings, furniture, packages, and con three plastics that consumers know best. struction applications such as shutters. A Polystyrene, or styrene as it is mere apt to be known by the public, can be molded, extruded, or otherwise processed by con ventional thermoplastics techniques. It is good deal of polystryene sheet is thermoformed into products for packaging (dairy tubs), appliances (refrigerator liners), boats, luggage, disposable plates, etc. available also as liquid solutions, adhe sives, and coatings. Polystyrene foams can readily be prepared and are characterized POLYSULFONE Thermoplastic. A mid-sixties development by having excellent low thermal conductiv ity, high strength-to-weight ratio, low (1965), polysulfone is another of those rigid, strong, and heat-resistant plastics water absorption, closed cell structure, excellent energy absorption, and good that were the focus of so much activity during the sixties and early 1970s. chemical resistance. These attributes have Polysulfone possesses a very high use made polystyrene foam of special interest temperature and very low creep under as insulation board for construction, as a load. It maintains a high degree of its protective packaging material (e.g., egg mechanical and electrical properties in 32 22586024 BFG21800 iRCRAFT: Component plastics parts like this thermoplastic polyester-framed filter are common small passenger planes. More recent activity is in adapting plastics to exterior parts-- eluding several planes with all-plastics bodies (wings and fuselage). IT: Calder's Universe, a sculpture based on \rylic, typifies art world's interest in plass for unique self-expression. SHIPPING DRUMS: Polyethylene can replace steel in 55-gal. drums, like that shown above, and is equally as applicable for 5-gal. pails. 22586035 33 BFG21801 continuous service at temperatures rang possible in-between. Flexible foams have ing from -150 to 300 to 345 F. Tensile outstanding cushioning characteristics, stress and modulus are high, and electrical excellent energy-absorbing properties, properties are excellent over a wide tem and long life. They are used in furniture perature range and even after immersion cushioning, carpet underlay, bedding, in water or exposure to high humidity. packaging, textiles, automotive seating, Polysulfone resins may be used as adhe sives and can be fabricated by extrusion, injection molding, blow molding, and ther moforming. Foamed grades are available. Typical applications include connectors, coil bobbins, meter housings, circuit carri ers, and other efectrical/electronic com ponents; in the automotive field, it is used for under-the-hood switch and relay bases and dome light bazels. Polysulfone also and safety padding. Rigid foams offer out standing insulating values, excellent com pressive strength, good dimensional sta bility, and outstanding buoyancy. They are used for insulating buildings, refrigerators, trucks, and cold-storage buildings, as a flotation medium for boats, and in the construction of furniture components such as drawers, table tops, head boards, chair frames and shells. has found a market in medical equipment The processing techniques available for where sterilization by steam, dry heat, or use with the foams are equally as varied. ethylene oxide is required. Consumers are Flexible foams are produced in the form of aware of it primarily in the form of compo slab stock or buns that can be subsequent nent parts for such appliances as coffee- ly fabricated or they can be molded direct makers, humidifiers, high-intensity lamps, ly into an end-product. Rigid foams can be and kitchen-range hardware. foamed-in-place (poured in liquid form POLYURETHANE into an open cavity where foaming then takes place), sprayed onto a surface, or (URETHANE) Introduced commercially only in 1954, the urethanes have already made an impact on a broad spectrum of U. S. industry. They are an extremely versatile plastic in terms of the forms in which they are available-- flexible or rigid foams, solid elastomers (or rubbers), coatings, adhesives, and sea lants. Their versatility also extends to chemical structure in that, although the urethanes are generally considered to be also molded into products. A newer tech nique known as reaction injection molding (RIM) or liquid injection molding (UM)can produce parts with nonporous, relatively solid-surface skins (known as integral skin foams). The technique involves injecting under pressure the isocyanate and the polyol directly into a mold where the reac tion takes place. It has been used for making automotive body parts, furniture, large housings, and similar products. thermosets, there are grades of urethane elastomers that are thermoplastic in na ture and are supplied in pellet form for molding, calendering, or extrusion. Urethane's major and best known form, however, is a foamed or cellular material. Like all urethanes, the foams are prepared by first reacting two liquid components-- polyols and isocyanates--together. In the presence of a blowing agent, this reaction will produce a foamed material having excellent thermal insulating properties. It is, however, possible to use water to gen erate the blowing agent Water readily re acts with the isocyanate-containing com ponents to form carbon dioxide which, in turn, becomes the blowing agent. Depending on the reaction and the chemi cals or additives used, the foams can ei FURNITURE: Shell of chair la molded In one piece of phenylene oxide. Other plastic uses ther be a soft, flexible material or a tough, In furniture: tables, sofa frames, head hard, rigid material, with all the variations boards, case goods, upholstery, cushioning. ____34 22586036 BFG21802 f- ! is coatings, urethanes impart outstanding rotective and decorative effects to wood, letals, rubber, textiles, concrete, paper, lather, plastics, and many other materials. 1 the form of elastomers, urethanes offer upriority to other elastomers in abrasion distance and toughness, and are used in pplications in which good performance nd long service life are important. Printig rolls, gaskets and seals, cable insulaon, drive and conveyor belts, solid tires, nd automotive parts are typical applicaons. The thermoplastic elastomers can, f course, be molded or extruded by conentional means. The elastomers can also ________________________ _____________ ,e p,[??sse<* bV reaction injection mold- BUSINESS MACHINES: Housings are prime ig (RIM) and this has become an impor- market area. The molded structural foam ant technique for producing automotive model (above) replaces one previously die cast Her panels, front ends, and bumpers that of re capable of meeting new automotive afety standards. JOLY (VINYL CHLORIDE) he birth of poly (vinyl chloride) or PVC or inyi as it is better known to the public, lates back to a German patent in the 910s, but it was not until the late 1920s hat a technically useful product was introluced in the U. S. By the start of World War !l, the significance of plasticizing PVC (that Is, adding a chemical known as a plasticiz-1 ir to make PVC flexible and processible) vas fully realized. It was during the war; hat the real importance of this polymer ' >ecame apparent when, due to the acute AUT0MQTIV INTERIORS: Dashboard is plasshortage of rubber, many companies fjC- S0'S steering wheel, knobs, glove comparturned to PVC and began to realize its ment, floor mat, upholstery, foam cushioning, idvantages. Since that time, the consump- trim, etc. ion of PVC has grown dramatically until oday it is second only to polyethylene in rolume use. because of its wide use in applications hat are close to consumers, like uphol stery, flooring, apparel and accessories, ecords, and wire insulation, vinyl is one of he better-known plastics. Vs a family, vinyls are usied mainly for their shemical and weathering resistance, high lielectric properties, or abrasion resistmce. Chemical resistance is excellent. Vilyls also enjoy a very slow rate of water * ibsorption. In general, they are recomnended for use at temperature ranges rom -65 to 175 F. Actually, >nly one poly (vinyl member of ct.hh.el.orviidney)lsoframPVilyC,. is al- gDrIoSwPiOngSAcBoLnEsSu:mSeirywanwd Institutional demand jor disposable dlnnerware, utensils, plates. :hough the most important one. The two 22586037 BFG21803 major sub-classifications in PVC are flexi lating properties, good moisture and ble PVC and rigid PVC. Flexible PVC is a chemical resistance. Silicones are water plasticized material (i.e., made flexible repellent, weather resistant, and highly re with chemical additives called `plasticiz sistant to mineral acids, and also corrosive ers') that is used for wire and cable insula salt solutions. tion, apparel, flooring, wall coverings, up Silicones are available as molding com holstery, automotive seats, garden hose, toys, and medical tubing. Rigid PVC is an unplasticized, hard, tough thermoplastic that is used in applications like doors and window frames, pipe and fittings, building pounds. resins, coatings, greases, fluids, and as a room temperature vulcanizing rubber (used for making molds for the casting of various plastics like urethane). The big outlet for silicones are in the panels and siding, rainwater systems, credit cards, and flooring. Major process ing methods are extrusion, injection mold electrical industry where they are used for coil forms, switch parts, induction heating apparatus, as insulation for motors and ing, blow molding, and calendering (for flexible PVC). generator coils, and in power cables. Sili cone fluids are used in the plastics and In cellular or foamed form, rigid PVC co rubber industry as mold release agents, polymer is being used for decorative mold lubricity and wear additives, lubricants, ings and trim to compete with wood. These and in controlling cell structure in foamed foamed vinyl profiles, can actually be cut plastics. and fabricated in much the same manner as their wood counterparts and will accept UREA nails and other fasteners. Thermoset. This plastic is another member PVC is also available in a liquid form, known as plastisols or organosols, that can be used for coating fabrics, paper, and metal, or rotationafly cast into dolls, balls, and automotive arm rests, dip molded in to gloves, or slush molded into boots. Foamed plastisols are an important part of of the amino family (as is melamine) and was developed in 1929. Like melamine, it is a very hard, scratch-resistant material with good chemical resistance, good electrical qualities, and heat resistance up to 170 F. They are available as molding powders or granules, as a foamed material, or in solu tion for lamination with wood and paper. dispersion resin technology and are used for calendered flooring, leather-like uphol Ureas are compression molded into prod stery, shoe fabrics, and carpet backing. ucts such as decorative housings, jewelry casings, lighting fixtures, closures, wiring Other types of vinyls are PVC copolymers devices and buttons. In liquid resin form, it like vinyl chloride-vinyl acetate resins that is used as baking enamel coatings, particle are used for phonograph records; polyvi board binders, and paper and textile treat nyl acetate, widely used as emulsions for ment. paints, adhesives, textile sizings, and coat ings; poly (vinyl alcohol), a water-soluble film; polyvinyl acetals (formats and butyr- als), widely used to provide adhesion and good mechanical properties in a variety of systems; and poly (vinylidene chloride), a tough, abrasion-resistant vinyl with better than ordinary heat resistance (212 F maxi mum service temperature) and used for packaging film, coatings, and monofila ments. Poly (vinyl butyral) is used in safety glass innerlayer for automotive wind shields. SILICONES Thermoset. Silicones were commercial ized in the early 1940s and are character ized by long-term heat resistance (silicone insulation has shown itself highly stable up LIGHTING: Office workers benefit from the Im proved lighting levels afforded by full-ceUIng to 350 to 590 F), excellent electrical insu- lighting diffusers base<^o^c^llc. 36 BFG21804 PROCESSING PLASTICS he ways in which plastics can be processd into useful end-products are as varied s the plastics themselves. /hile the processes differ, however, there re elements common to many of them. In le majority of cases, thermoplastics com ounds in the form of pellets, granules, ake, and powder, must be melted by heat 3 they can flow. Pressure is often involved i forcing the molten plastic into a mold avity or through a die and cooling must e provided to allow the molten plastic to arden. With thermosets, heat and presjre also are most often used, only in this ase, the heat (rather than cooling) serves > cure or set the thermosetting plastic, nder pressure, in the mold. When therloplastics or thermoset resins in liquid >rm are involved, heat and/or pressure eed not necessarily be used, although in lany casting techniques, intended for igh-speed production, they do play a role, is descriptions of processes that follow jver the basics of the major manufacturg systems. It should be recognized, howter, that there are variations in virtually tery process, perhaps aimed at servicing particular market or servicing a particu- r plastic, that represents some degree of aviation from the basics. A good analogy might be to trapping a balloon inside a mold, inflating it so that it sticks to the inside walls of the mold cavity, then somehow solidifying it in that shape before removing it. There are many variations possible in the basic process, however. Where differences do exist is in the way the tube or parison is made (you can extrude it or injection mold it), whether the parison is to be used hot as it comes from the extruder or injection molding machine (as in conventional blow molding) or stored cold and then reheated (as in cold preforming molding), and the manner in which the parison is transferred to the mold for blowing or the mold is moved to the parison (using rotating wheels, rotating tables, rotating molds, etc.). BLOW MOLDING LOW MOLDING enerally used only with thermoplastics, is process is applicable to the produc er) of hollow plastics products such as ottles, gas tanks, and carboys. Historical, blow molding began during World War However, it did not become an important ocess until well into the 1950s when BLOW MOLDING: Diagram of continuous ex trusion blow molding set-up, using a rotating horizontal table. Plastic parison (in cylindrical shape) is extruded from die into mold which closes on the parison (knife cuts the parison off from the extrudate). Mold then rotates to gh-density polyethylene (the rigid mate- second station where air is injected into the si used for bleach and detergent bottles) parison (still hot and therefore formable) to jcame available and commercial blow blow it out to the shape of the inside mold olding machines first started to be mar cavity. At third station, the blown part is al ked. lowed to cool and set (i.e., harden). Mold finally rotates to last station where finished;' part ssically, blow molding involves the melt- (in this case, a bottle) is ejected from mold. g of the thermoplastics resin, then fofm- g it into a tube-like shape (known as a irison), sealing the ends of the tube, and CALENDERING jecting air (e.g., through a needle insert- Calendering can be used to process ther I in the tube) so that the tube, in a moplastics into film and sheeting, and to iftened state, is inflated inside the mold apply a plastic coating to textiles or other id forced against the walls of the mold. supporting materials. n cooling, the part, now conforming to In calendering film and sheeting, the plas e shape of the cavity, is solidified and tic compound is passed between a series ected from the mold as a finished piece. of three or four large, heated, revolving 37 22586039 I 1 Li BFG21805 L I rollers which squeeze the material be blade or knife. The plastic coating com tween them into a sheet or film. An analogy pound is placed on the material just in in this case might be flattening out a pasty front of the knife, and is spread out over dough mixture with a rolling pin. The the material. The thickness of the coating thickness of the finished material is con is regulated by the speed at which the trolled by the space between the rolls. The material is drawn under the knife, and the surface of the plastic film or sheeting may position of the knife. be smooth or matted, depending on the In roller coating, two horizontal rollers are surfacing on the rollers. used. One roller picks up the plastic coat CASTING ing solution on its surface and deposits it on the second roller which, in turn, depos Resins for casting emerged a little over a its the coating solution on the supporting half century ago, but formulations suitable material. for increasingly widespread use date back only about 30 years. Most recently, plastics in the form of fine powders, have proved popular in the coat Casting may be used both with thermo ing of a wide range of substrates. Two of plastics and thermosets to make products, the methods for applying powder coatings shapes, rods, and tubes, by pouring a are fluidized bed and electrostatic spray liquid monomer-polymer solution into an coatings. In fluidized bed coating, the ob open or closed mold where it finishes ject to be coated is heated and then im polymerizing into a solid. Film and sheet mersed in a dense-phase fluidized bed of ing can also be made in this way by casting powdered resin; the resin adheres to the directly into a flat open mold, casting onto heated object and subsequent heating a wheel or belt, or by precipitation in a provides a smooth, pinhole-free coating. chemical bath. Electrostatic spraying is based on the fact One essential difference between casting that most plastics powders are insulators and molding is that pressure need not be with relatively high volume resistivity'val used in casting (although large-volume, ues. Therefore, they accept a charge (posi complex parts can be made by pressure tive or negative polarity) and are attracted casting methods). Another difference is that the starting material is usually in liquid to a grounded or oppositely charged ob ject (which is the one being coated). form rather than solid (such as pellets, granules, flake, powder, etc.). A third is COATING that the liquid is often a monomer rather than the polymers used in most molding compounds. A variation on casting is known as liquid injection molding (UM) and involves the proportioning, mixing, and dispensing of liquid components and directly injecting the resultant mix into a mold which is clamped under pressure. COATING Thermosetting and thermoplastic materi als may both be used as a coating. The materials to be coated may be metal, COA TING: A typicalcoating set-up, known as a wood, paper, fabric, leather, glass, con 3-roll nip fed reverse roll coater. Plastic feeds crete, ceramics or other plastics. from dam through nip between steel metering and applicator rolls, rotating in the same direc Methods of coating are varied and include tions. At bottom of the applicator roll, plastic knife or spread coating, spraying, roller is laid on top of the substrate (e.g., fabric, coating, dipping, and brushing. Calender paper, etc.1 as It comes in contact with the ing of a film to a supporting material is also substrate at nip between applicator roll and a form of coating. backing roll (which carries the substrate up from the bottom of set-up). Doctor blade Is In spread coating, the material to be coat used to scrape off excess plastic from applies- Med passes over a roller and under a long -38. 22586040 BfG2l86 COMPRESSION MOLDING the mold. It is while the heated mold is Jompression molding is the most comnon method of forming thermosetting maerials. Until the advent of injection moldng, it was the most important of plastics processes. The earliest application of com pression molding as a manufacturing pro cess was early in the nineteenth century Vhen Thomas Hancock patented a pro- closed that the thermosetting material un dergoes a chemical change which perma nently hardens it into the shape of the mold. The three compression molding factors--pressure, temperature and time the mold is closed--vary with the design of the finished article and the material being molded. ;ess for molding rubber. The first patent an using it to mold plastics was issued in he U.S. in 1870 to John Wesley Hyatt developer of the first U.S. commercial alastic, celluloid) and Isaiah Hyatt. EXTRUSION Extrusion is the method employed to form thermoplastic materials into continuous sheeting, film, tubes, rods, profile shapes, or filaments, and to coat wire, cable, and Compression molding is simply the cord. iqueezing of a material into a desired In extrusion, dry plastic material is first shape by application of heat and pressure loaded into a hopper, then fed into a long o the material in a mold. heating chamber through which it is COMPRESSION MOLDING moved by the action of a continuously revolving screw. At the end of the heating chamber the molten plastic is forced out through a small opening or die with the shape desired in the finished product. As the plastic extrusion comes from the die, it is fed onto a conveyor belt where it is MOLDING COMPOUND cooled, most frequently by blowers or by immersion in water. An over-simplified analogy would be to compare the tech nique to a household meat grinder or to MOLD OPEN squeezing toothpaste out of a tube. In the case of wire and cable coating, the thermoplastic is extruded around a contin uing length of wire or cable which, like the plastic, passes through the extruder die. The coated wire is wound on drums after cooling. MOLD CLOSED In producing wide film or sheeting, the COMPRESSION MOLDING: Basics of a simple plastic is extruded in the form of a tube. two-piece compression mold. Plastic molding This tube may be split as it comes from the material is loaded into lower half (cavity) of the die and then stretched and thinned to the heated mold (shown at too). Top half of the dimensions desired in the finished film. halves similar process, as Jj II 8604.1 dio frequency dielectric techniques.) The marketplace, coextrusion has been adaptmold is then closed, pressing down on the ed to the production of products like pack- Li BFG21807 GEAR REDUCER EXTRUSION HOPPER FEED THROAT SCREW HEATED , BARREL HEATEO BANDS BREAKER PLATE MELT \ THERMOCOUPLE DIE ADAPTER EXTRUSION: In a basic single-screw extruder, plastics pellets (or powders) are fed through the hopper, through the feed throat, and into a screw that rotates in a heated barrel. The rotation of the screw (which is powered by the drive motor) conveys the plastic forward for melting and delivery through the breaker plate (reduces the rotary motion of the melt), through the adaptor, and into the die which dictates the shape and size of the final extrudate. Over simplified analogies that can help in understanding extrusion are the operation of a household meat grinder or squeezing toothpaste out of a tube. structure several layers of different plas or thermal, high-frequency, or ultrasonic tics, each offering varying degrees of sealing. moisture resistance, gas barrier proper ties, adhesive qualities, economics, etc. Forming. In working with thermoplastics sheets, several approaches are possible. In FABRICATING Fabricating is an over-all description for the various operations performed on sec ondary shapes like sheet, film, rod, tube, or profiles, to turn them into finished prod ucts. Fabricating divides into three broad cate gories: the machining of solid shapes; the cutting, sewing, and sealing of film and sheeting; and the forming of film and sheet. one, sheet can simply be bent and joined together by such techniques as hot gas welding to form structural products like hoods, venting systems, duct work, stor age tanks, and allied products. Thermo plastic sheet can also be scored and fed into conventional paperboard creasing and folding equipment to make a standard plastic box or carton. The plastic blank can also be beaded for added strength before being creased and folded into a box. The major method for forming film or Machining. Using techniques quite com mon to metal, wood, and other industries, plastics shapes can be turned into end- products by such methods as grinding, turning on a lathe, sawing, reaming, mill ing, routing, drilling, and tapping. sheet, however, is known as thermo forming (i.e., heating and sheet and then forming it while it is in its softened state by pushing it or pulling it into or over a mold). This technique has become a major pro cessing method in its own right and is covered below. Cutting, sewing, and sealing of film and sheet. In this category of fabricating fall all FINISHING the operations involved in turning plastics The finishing of plastics includes the dif film and sheeting into finished articles like ferent methods of adding either decorative inflatable toys, garment bags, shower cur or functional surface effects to a plastic tains, aprons, raincoat, and luggage. In product. Plastics, of course, are unique in making these products, the film or sheet is that color and decorative effects can be first cut to the desired pattern by hand, in added to plastics prior to and during man die-cutting presses, or by other methods. ufacturing. Pigments and dyes, for exam The pieces are then put together using ple, are compounded into the plastic be such assembly techniques as sewing, fore they are processed so that color is 40 22586042 BFG21808 ntegral to a plastic product and is continjous throughout the piece. Two-color afastics moldings are also possible, as is currently being done by molding typewrit er keys in one piece. Decorative surface textures can also be incorporated into a plastic part by simply incorporating such textures in the surface of the mold. However, plastics parts, whether film and sheeting or rigid products, can be postfinished in a number of ways. Film and sheet can be post-embossed with textures and they can be printed by letterpress, gravure, or silk screening. Rigid plastics parts can be painted or they can be given a metallic surface by such techniques as metallizing, barrel plating, or electroplat ing. Another popular method is hotstamping, in which heat, pressure, and dwell time are used to transfer color or design from a carrier film to the plastic part. A more recent decorating technique is known as in-mold decorating and involves the incorporation of a printed foil into a plastic part during molding so that it be comes an integral part of the piece and is actually inside the piece under the surface. This technique was originally developed to decorate melamine dinnerware. FOAM PLASTICS MOLDING The manufacture of foam plastics parts cuts across most of the processing tech niques covered in this section. Foams can be used in casting, calendering, coating, rotational molding, blow molding, even injection molding and extrusion. Typical requirements in such instances are for the incorporation of blowing agents in the resin that decompose under heat to gener ate the gasses needed to create the cellu lar structure and for various controls to accommodate the foaming action. There are, however, some techniques unique to foamed plastics. When working with expanded polystyrene beads, for ex ample, to produce cups, picnic dishes, etc., various "steam-chest" molding meth ods are used. The application of steam causes the beads to expand and fuse to gether. When working with urethene foams, it is possible to use spray guns or mixing- STYRENE FOAM MOLDING 22536043 RAW PRE- MATERIAL expander BEAD SCREENER MOLOING MACHINE FOAM MOLDING: Among the many variations in molding foamed plasties is this set-up for steam chest molding expandable styrene beads into products like foam cups, novelties, ice buckets, picnic goods, building products, etc. In this operation, the expandable beads, containing a blowing agent, are pre-expanded with steam, then screened to remove large clumps. The expanded beads are next blown into a storage hopper and allowed to dry and stabilize. From here, they teed Into the final mold where steam is again used to complete expansion of the beads so that they fill the mold and fuse together. Water is used for cooling, prior to opening the mold and removing the finished foamed styrene part. 41 BFG21809 metering machines to mix the liquid ingre In producing a flat surface, impregnated dients together and direct them into a sheets are stacked between two highly cavity or mold or surface objects with polished steel plates and subjected to heat them. The mixed ingredients start to foam and high pressure in an hydraulic press up after leaving the dispensing equip which cures the plastic and presses the ment. plies of material into a single piece of the There is a unique technology that has also sprung up in connection with the molding of structural foam--foams with integral skins (i.e., solid) and a cellular core and with a high strength-to-weight ratio. When processing structural foams, several tech niques are in use, mostly related to injec tion molding. One such method is known as the "low-pressure" system because the desired thickness. In making high-pres sure tubing, resin-treated reinforcing sheets are wrapped, under tension and/or pressure, around a heated rod. The assem bly is then cured in an oven. In producing formed shapes, the reinforcing material is cut into pieces that conform to the contour of the product, fitted into the mold and cured under heat and pressure. molds are only partially filled with the plastic melt (using relatively low pressure). INJECTION MOLDING The pressures generated within the melt as The process of molding was patented by the blowing agent decomposes and the John and Isaiah Hyatt in 1872 to mold the melt expands are sufficient to fill the mold. cellulose nitrate material (known as cellu A second technique is known as the "high-pressure system." This differs from low-pressure in that the plastic melt (with the blowing agent incorporated in it) is injected under high pressure into the mold cavity to completely fill it. To accommo date the expansion of the melt as it foams, the mold itself is expanded. loid) that they had developed. The first multi-cavity mold (i.e., to make more than one part at a time) was introduced by John Hyatt in 1878. Modern technology in injec tion molding, however, did not begin to develop until the late 1930s. Its growth was extremely rapid during the '40s and '50s and by the 1960s, it had already by-passed compression molding as the major plastics A third technique known as "expansion processing method. Originally used ex casting" involves the use of closed metal pressly for processing thermoplastics, the molds that are filled with expandable pel technique was adapted in the mid-1960s lets, then subjected to a heating cycle, to also handle the thermosets and in the during which the material expands and early 1970s to molding reinforced plastics fuses. (glass-thermoset resin combinations). Systems are also available to extrude The basic concept of thermoplastic injec structural foams with integral skins and tion molding revolves around the ability of cellular cores. Many of these involve con a thermoplastic material to be softened by ventional extruders and modified tech heat and to harden when cooled. In most niques. Others involve special systems that operations, granular material (the plastic use unique die design and shaping dies to resin) is fed into one end of the heating control the foaming action. cylinder (usually through a feeding device known as a hopper), heated, and softened HIGH-PRESSURE LAMINATING (plasticated or plasticized), forced out the other end of the cylinder (while it is still in the form of a melt) through a nozzle and Thermosetting plastics are most generally into a relatively cool mold held closed used in high-pressure laminating which is under pressure. Here, the melt cools and distinguished by the use of high heat and hardens (cures) until it is fully set-up. At pressure. These plastics are used to hold this point, the mold opens and the molded together the reinforcing materials that part in solid form is removed. comprise the body of the finished product. The reinforcing materials may be cloth, paper, wood, or glass fibers. Originally, the favored technique for forc ing the plastic through the heating cylin der and into the mold was with an injection The end product of high-pressure laminat plunger. Machines using this system are ing may be plain fiat sheets, rods, tubes or known as plunger machines. The more formed shapes. popular and dominant technique today, 42 22586044 BFG2l8W INJECTION MOLDING INJECTION MOLDING: Diagram of reciprocating screw injection molding machine. Plastics pellets feed through the hopper into the screw (much like the screw in an extruder) where they are compacted, melted, and pumped by the rotation of the screw past the non-return flow valve (allows material to flow right to left, but not from left to right) to the front of the screw where it is allowed to accumulate. At the proper time, the rotation of the screw is.stopped and the amount of molten plastic in front of the screw is injected into trie mold, using the screw as a plunger activated by the hydraulic injection cylinders. In the mold, the molten plastic flows throughout the cavity, completely filling it. The plastic is then allowed to cool and harden, the mold is opened, and the finished part removed. The back end of the machine shown above contains the motors and drives needed to power the machine. however, is based on a rotating screw (like putty-like form that does not flow freely the screw used in extrusion) that moves like pellets or granules do. The machines back and forth within the heating cylinder use either a screw or plunger to then force to help soften the plastic and to force it the heated reinforced plastic through the along the cylinder and into the mold. Ma cylinder and into the mold. chines using this system are known as re ciprocating screw machines. REACTION INJECTION The machines used for molding thermo sets are called in-line screw injection ma chines or direct screw transfer machines. They involve basically the same system as in the injection molding of thermoplastics. Temperatures differ, however, as does the MOLDING (RIM) This technique (also sometimes called liq uid injection molding) has thus far been used primarily for molding polyurethane elastomers or foams into end-products with solid integral skins and cellular cores. design of the screw. In addition, machines Basically, two or more pressurized reactive for thermosets are also designed so that streams (in the case of urethane, this the screw stops turning when the exact means an isocyanate and a polyol) are volume of plastic needed to fill the mold impinged together under high pressure in has reached the end of the cylinder. At this a mixing chamber. The resulting mixture is point, the screw then moves forward under then injected, under low pressure, into the hydraulic pressure to force the plastic, into mold where the reaction begins and con the mold. Most of these changes are in tinues until the liquid mixture-has set up tended to accommodate the fact that ther into a solid or cellular finished product. mosets, unlike thermoplastics, cure with the continued application of heat. Until the advent of RIM, standard liquid casting systems for urethanes involved low In the injection molding Of reinforced plas feedline pressures and some means of tics based on thermoset resins with glass mechanical mixing (e.g., rotating blades). fiber reinforcements, stuffer cylinders, In contrast to these systems, RIM offers rather than hoppers, are used to push the such advantages as self-cleaning mixing plastic into the machine. This is ncessary heads, higher outputs, lower cycles, im since the reinforced plastics are in a proved products. 43 REINFORCED PLASTICS PROCESSING Reinforced plastics are composites in which resins (acting as a binder material) are combined with reinforcing materials (usually in a fibrous form) to produce products that have exceptional strengthto-weight ratios and outstanding physi cals. The resins may be either thermosets or thermoplastics. However, the thermo setting resins, which were the first plastics to be adapted to this concept (polyester resins, in particular), dominate the field to a large degree. Reinforced thermoplastics can be injec tion molded, rotationally molded, or ex truded on conventional equipment. There are even reinforced thermoplastics sheets that can be "cold" stamped into shape using matching metal molds that form the parts. It is called cold stamping because the molds are kept at or slightly above room temperature. The sheets, however, must be pre-heated. Most high-volume reinforced plastics pro cesses in use today, however, do involve the application of pressure. The most pop ular of these is known as matched metal die molding and is basically a compression molding system in which the reinforced thermoset plastics are placed between matching heated molds and held under pressure until the fiber-filled resin polymer izes (i.e., hardens into a solid). Where differences do exist is in the way in which the reinforced plastic material is fed into the mold. The three forms available today include: 1) preforms shaped from the fi bers to the approximate shape of the parts to be made and placed into the mold (more uniformity in product, less waste); 2) bulk molding compounds made up by mixing REINFORCED PLASTICS MOLDING It is also possible to use modified injection molding techniques with reinforced ther moset resins (see Injection Molding, above), although by and large, the pro cessing of reinforced thermoset resins has developed a technology all of its own. For example, it is possible to process these reinforced plastics into extremely large parts (e.g., boat hulls, storage tanks, etc.), using little or no pressure. One such sys tem is known as hand lay-up and simply involves the manual placement of the rein forcing fibers (in the form of fabrics, woven roving, or mat) into a mold, impreg nating the lay-up with liquid resin, squeez ing out entrapped air with a squeegee, and then allowing the part to cure, with or without heat, into a finished product. Other variations on this method aimed at improving surface finish and providing a more uniform product involve the use of plastic film or rubber bags placed on top of the lay-ups and forced against them by pulling a vacuum under the film or by applying air pressure over the bag. Another approach to making a reinforced plastic product is known as "spray-up." In this process, chopped glass and resin are deposited simultaneously in a mold using special spraying equipment. The film-resin mix is then rolled by hand to remove air and allowed to cure at room temperature or heated to achieve an accelerated cure. BEFORE CLOSING REINFORCED PLASTICS MOLDING: Matcheddie molding is one technique tor producing RP parts. Basically, it is a compression mold ing process (see Compression Molding), in which resin and glass fibers are shaped into the finished product under heat and pressure between the two halves of a mold (male and female halves). The glass fiber reinforcements are laid over the male mold in the form of a "preform"--a combination of glass and resin preformed before molding to the basic shape of the part to be molded. Additional liquid resin mix is added before mold is closed. resin, fibers, catalyst, etc., together into a putty-like mass that can be placed in the mold as is or extruded into a rope-like form for easier handling; and 3) sheet molding compounds, in which fiber, resin, and other ingredients are precombined into a sheet form that can easily be loaded into the mold; either manually or with automatic techniques. Other unique reinforced plastics process ing methods include: pultrusion, a method 44 22586046 I tarn* BFG21812 INJECTION MOLDING: Machine sizes available today can go up to 1500-ton damping force (capable of molding a 25-lb. part) and higher (to 3000 tons or better). Hopper tor receiving plastics pellets is to operator's right, mold area to his left, behind safety gates. COA TING: Passing through ovens and se ries of pressure rolls, an expanded vinyl coating is applied to a substrate. Technique can be used to produce products ranging from flooring to wallpaper to various Minds of wearing apparel. EXTRUSION: Strands emerge from the die of a compounding extruder and pass into a water bath for cooling. Changing die size can vary extrudate from thin filaments all the way up to 48-in.-diameter sewage pipe. 2586047 STRUCTURAL FOAM MOLDING: Typical plant set-up shows two 150-ton presses molding plastics foam panels (stacked, foreground) for underground swimming pool. Because lower pressures are used in this process, these 65-lb. panels can be foam molded in a single shot. 45 BFG21813 L for making continuous shapes (e.g., stair railings) by pulling resin-impregnated fi bers through shaping dies and curing op erations (it's the reinforced plastics in dustry's counterpart to thermoplastic ex trusion) and filament winding, a method for making cylindrical shapes (e.g., rocket motor cases) by winding resin-impreg nated fibers around a mandrel, curing the part, and removing the mandrel. ROTATIONAL MOLDING This technique, like blow molding, is used to make hollow one-piece parts. Essentially, rotational molding consists of charging a measured amount of plastic resin info a warm mold which is rotated in an oven about two axes. In the oven, the heat penetrates the mold, causing the plastic, if it is in powder form, to become tacky and stick to the mold surface, or if it is in liquid form, to start to gel on the mold surface. Since the molds continue to ro- ROTATIONAL MOLDING tate while the heating is going on, the plastic will gradually become distributed evenly on the mold cavity walls through gravitational force. As the cycle continues, the polymer melts completely, forming a homogeneous layer of molten plastic. After cooling, the molds are opened and the parts removed. THERMOFORMING Basically, thermoforming consists of heat ing thermoplastic sheet to its softening temperature and forcing the hot and flexi ble material against the contours of a mold by mechanical means (e.g., tools, plugs, solid molds, etc.) or by pneumatic means (e.g., differentials in air pressure created by pulling a vacuum between sheet and mold or using the pressures of com pressed air to force the sheet against the mold). The various forming techniques are generally described in terms of the means used to form the sheet, such as vacuum forming, pressure forming, plug-assist forming, etc. In the early days of thermoforming, the process involved heating the sheet in a separate oven and then transferring the hot sheet to the forming press. As the industry became more sophisticated, how ever, automatic machinery combining heating and forming in a single unit evolv ed. At the same time, the industry moved from the original concept of sheet-fed ma chines (i.e., feeding a single die-cut sheet into the forming press) to continuous oper ation feeding off a roll of plastic or directly from the mouth of an extruder. ROTATIONAL MOLDING: Diagram of basic system indicates how plastics (which feed in through the inlet) are formed into hollow pro ducts Inside a closed mold while the mold is being rotated about two axes and heat is ap plied. Spindle is turned on a primary axis, while molds are rotated on a secondary axis. During rotation, the heated (molten) plastic is distributed evenly on the inside walls of the mold cavity through gravitational force. After cooling, the mold is opened and the finished part in the shape of the cavity is removed. Most recently, the thermoforming industry has begun to evaluate the idea of reducing the amount of heat applied to a thermo plastic sheet, or even eliminating it entire ly, and then using the higher pressures of stamping presses to form a part. These techniques are known as cold forming (in which certain plastics, like ABS, have been developed that can be formed at room temperatures, using standard metal work ing techniques and equipment), solidphase forming (in which the material is heated below melt temperature and formed while in this heated, solid state), and com pression molding (where glass-reinforced material is heated above its melt tempera ture but has the consistency of wet card board due to its reinforcement and can be formed in the compression press). 2258604.8 BFG21814 THERMOFORMING } / . ^ |f ABC ^.... \ THERMOFORMINQ: This variation on the thermoforming of plastic sheet Is known as plugassist vacuum forming. In operation, the plastic sheet is clamped in place and heaters move in to heat the sheet top and bottom to soften it (A). Heaters are then withdrawn and the frame holding the sheet is lowered down to contact the mold. At this point, the plug-assist is lowered into the softened sheet, stretching it down to the bottom of the mold cavity (B). After the plug-assist has reached its closed position, a vacuum is drawn through the ports to pull the stretched sheet completely into the cavity and finish the forming. Next, the plug-assist is withdrawn, the formed sheet is cooled, and the clamps are opened to remove the formed part from the framefC). ! TRANSFER MOLDING remain with the molded pieces and must Transfer molding is most generally used subsequently be removed. for thermosetting plastics. TRANSFER MOLDING This method is like compression molding in that the plastic is cured into an infusible state in a mold under heat and pressure. It differs from compression molding in that the plastic is heated to a point of plasticity before it reaches the mold and is forced into the closed mold by means of an hydraulically-operated plunger. Transfer molding was developed to facili tate the molding of intricate products with small deep holes or numerous metal in serts. The dry molding compound used in compression molding sometimes disturbs the position of the metal inserts and the pins which form the holes. The liquefied plastic material in transfer molding flows around these metal parts without causing them to shift position. One popular method is known as plunger molding and is illustrated at right. A ram forces the plastic from the pot beneath it into the two cup-shaped mold cavities. Diagram shows mold as it is opened after cavities have been filled and parts have cured. Cuff (the residual disc of material left in the pot) and the sprue (or runners that carry the plastic from pot to cavities) TRANSFER MOLDING: Plastic transfers from "pot" or "well" through runners and gates Into cavities retained in a closed heated melt. System shown above is known as "plunger molding" and is described in accompany ing text. 47 22586049 BFG21815 PLASTICS IN OUR FUTURE I As man ventures further into space, aerospace engineers turn increasingly towards plastics to design the advanced vehicles that will be needed. Materials shape the age in which we live. our children play with, even the play They determine the form and function of ground equipment they play on. where we live and how we live and how we work and how we play. It is for good and significant reason that so many of the ages in the course of man's development are described in terms of the materials that guided these developments. Yet the best is still to come. As a family, many plastics materials are light in weight, yet pound-for-pound much stronger than a number of conventional materials. Translated into the world of tomorrow, they provide the wherewithal for architects It thus becomes even more remarkable to move beyond the conventional box when we evaluate the impact that plastics shape of today's homes to fulfill the dream have had on the world today to realize that of buildings with more curves and flowing their existence dates back to just a little forms, with more open spacing based on over a hundred years ago. Plastics are still plastics members that can span large evolving, still changing, still improving. areas without buckling, with thinner exter Their potential impact on society as we ior shells that provide unmatched flexibili- move into the twenty-first century looms -- ty in executing new and unusual designs. larger and larger. We see it today in the extensive use of The seeds are already being sown. As we have tried to indicate in this brochure, it is probably impossible to define the totality of the plastics experience in our everyday lives. They are there in so many ways.... in apparel, in home furnishings, in con struction, in lighting, in furniture, in trans portation, in packaging, in medical use. in plastics in the futuristic structures at World's Fairs and Olympic sites, in mo dern-day sports stadia, in geodesic domes. Chances are that if the domed cities that have been standard sciencefiction fare for decades ever do come to pass, it will be a plastic dome that will do the covering. recreational activities, in communications, Plastics have more to offer. They can be in electronics, in housewares, in applianc shaped easily, inexpensively and accurate es, in aerospace, in storage tanks and ly into large parts and transported pipes, in luggage, in insulation, in the toys economically. Modern concepts of pre- 48 22586050 I i BFG21816 1 fabricated building components mass- 1960s--inflatable chairs, transparent produced in factories and trucked to the acrylic tables, stylish reinforced plastics building site have evolved in part from chairs--were sparked by the availability of this plastics capability. Tomorrow, it may plastics. be low-cost housing for underdeveloped countries that will benefit. Beyond the home, visionaries see strong roles for plastics in transportation. The Another straw in the wind: already com same factors of light weight, strength, de- mercial today are plastics bathroom units, signability, and ease of maintenance will molded and formed in one piece complete make plastics as important to the exterior with tub, surround, cabinet, sink, toilet. of the automobile (hoods, trunk lids, entire Tomorrow's beneficiary: urban renewal. bodies) as it currently is to the interior of Visualize a building completely gutted in the automobile. When automotive engi side and then transformed into usable liv neers finally do come up with the "safety ing space by hoisting a one-piece plastics car" of the future that will encase us in an room with a crane and lowering it in place energy-absorbing shell, chances are again within the building shell. good that plastics will be heavily involved. These same properties and characteristics of various plastics that could revolutionize building construction in the decades to come may exert an equally as strong influ The futuristic cars that Detroit is showing to the public today already use reinforced plastics bodies, urethane bumpers and ends, break-away projections and non- ence on building interiors. Mobile plastics shattering plastics windows. walls and room dividers will enable us to Even more exciting are the opportunities change living space as we need it, around for plastics in the "people movers" of a central utility core. Printed plastics sur tomorrow--the mass transportation con facing films will help us change a room's cepts based on monorails, electric cars, color scheme just as quickly. And interior guided autos. Again, you can see the fu designers are only now just touching on ture today in the large number of plastic the potential of plastics in furniture--not in bodied vehicles in use at various amuse imitation of the standard wood shapes we ment parks and airports in the U. S. And if know today, but in the free-flowing shapes you look a little harder you can find small and combinations of transparency, color, passenger airplanes based almost entirely and texture that only plastic can provide. on plastics, including wings and fuselage. Significantly, the revolution in furniture They've been commercial and in use since design that came out of Europe in the the late 1960s. 22586051 Ten-acre air-supported dome tor sports stadium uses plastics to advantage, as do other avant-garde new building concepts. 49 BFG21817 The exciting thing about plastics is that in that could someday give us the science- the decades to come they will be working fiction wrist-watch TV leans heavily on their magic equally as effectively in areas plastics. And you will find plastics in the that are considered commonplace next to rockets and the exploring machines and construction and transportation, areas the space stations that will be used in the that are accepted by the public and rarely decades to come as we move further and questioned, areas like housewares and further out into space. It's already hap toys and packaging. It is difficult to pin pening today. descriptions like "revolutionary" on the influence that plastics has already had in these markets, but revolutionary it was. Just try to remember the limitations in function, form, and color that character ized many of these products before the advent of plastics. Accept the fact that the end is not yet in sight. This is especially true in the areas in which plastics packag es will impact on the concept of a fully automated supermarket or other retail establishment--plastics packages that can be more easily, and more safely, handled, plastics packages that may offer longer shelf life without deterioration of the con tents, superfunctional packages that bend or expand or otherwise change in size or shape to make storage, delivering, and dispensing functions that much easier. To the plastic chemist it is all grist for the same mills. It is his job to come up with a material that will meet a need, whether that need is for a heat-resistant plastic that will protect an astronaut or for a plastic housewares item. But he also knows that when you're working with plastics, the avant- Plastics are not the substitute that so many people still consider them. It is true they evolved as a substitute-type material (i.e., to replace ivory) and it is true that one period of great activity took place in World War II to replace unavailable materials that were needed to meet consumer and mili tary demands. But that was the wonder of plastics--that man could create a synthet ic to meet his needs. The age of synthetics never did mean that the older, more con ventional materials had lost their value; rather, it simply meant that it was not available to the extent needed to cover our demands and that man's creativity and ingenuity had come up with alternate pos sibilities: plastics. Of course, although the image still exists for plastics, the substitution syndrome has long since become a part of `ancient' his tory. It does crop up from time to time, whenever a potential materials shortage looms and the polymer chemist unleashes his imagination to resolve the problem (e.g., concerns about paper shortages in England and Japan in the late 1960s led to garde and the commonplace can become the development of plastics `papers' that inter-related. The same heat-resistant plastic that protected the astronauts showed up years later in the bowl of a smoking pipe. could be used for packaging, in bags, to write on, to print on, etc.). But by and large, plastics have become prime materials--quite different, quite unique, As impossible as it is to define today's and unlike many of the materials that I plastics experience, it is even more diffi have gone before. cult to describe its potential for the future. And after 100 years, we're still learning There are very few areas of technological how we can change them, how we can use development in which plastics are not in them even better and more effectively. volved. The biochemical techniques that Plastics are already an expression of our have enabled doctors to replace diseased times and certainly one of the means by parts of the body is a plastics devel which today's dreamers and planners will opment--and still in its infancy. The sci forge the world of tomorrow. It is probably ence of fiber optics that has such disparate most significant that in the world of mod uses as lighting the dashboard in our auto ern art, so many artists and sculptors have mobile or allowing doctors to examine us internally in a way that was completely impossible before can be based on plastic filaments or plastic-coated glass filaments. turned to plastics as the most suitable means of self-expression. In a way, the artist, in his rejection of conventional shapes and forms and materials, is empha Nuclear energy plants use lead-filled poly sizing plastics as a material with a life and ethylene slabs as protective shielding. The individuality of its very own--and in har concept of miniaturization in electronics mony with the times in which we live. 22586052 en BFG2V8'8 1 WHAT IS SPI? The Society of the Plastics Industry, Inc., ership for the responsible advancement of (SPI), represents some 1400 member com the entire plastics industry." SPI sponsors panies who are responsible for about 75% many special research projects in areas of plastics sales in the United States. In such as resource recovery, combustibility, effect, it is a member-run federation of the industry's future growth potential and many groups; through nearly 50 divisions, worker safety at major private research special purpose groups, market councils, organizations. SPI is also responsible for regional sections, and service committees, many information programs, literature, SPI gives focus, perspective and direction surveys, reports, newsletters, and hand to its members' specific interests. Members include processors, machinery manufacturers, mold makers and resin producers. The processor, who converts books for industry and public use. SPI's service committees provide liaison with government agencies, code and regulatory groups, and many other associations. plastic into a finished or semi-finished product, represents a two to one majority in the membership of SPI. The plastics processors are the backbone of the indus try and their operations are proprietor con trolled. Most are small businesses with a hundred or so employees. Incorporated in 1937, SPI has grown with the dynamic industry it represents. In addi tion to the Society's New York office, there is a Mid-Western office, 3150 Des Plaines SPI also functions as the industry's spokesman on public issues, and serves as the focal point of organization of the in dustry for their solution. Each year more schools, colleges and uni versities are adding instructions in plastics to their curricula. As interest grows, new courses are added,-old courses realigned to better prepare students for the needs of the plastics industry. Avenue, Des Plaines, Illinois, 60018 (312) A wealth of information is contained in 297-6150; a Western office, Saddleback trade and technical magazines and techni Sq., 12440 Firestone Blvd., Norwalk, CA, cal books for and about the plastics indus 90650, (213) 331-0340, an Eastern Office, try. A listing of these publications is availa 1575 Rte. 23, Butler, N.J. 07405 (201) 838- ble. 2222, and a Washington office, 1101 17th Street, N.W., Suite 204, Washington, D.C., 20036(202)331-0340. The Society of the Plastics Industry, Inc., has a speakers bureau with a number of slide presentations ready for use. Infor Its 50 operating units work toward the mation on the bureau is available from basic SPI objective of "... providing lead SPI/New York. 51 22586053 BFG21819 The information in the foregoing has been adapted from data obtained from a wide va riety of sources. It is not intended to convey approval by the Society of the Plastics Indus try for using any specific plastic in any specific application. Rather, it is intended to provide the reader with some measure of perspective in understanding the versatility inherent In the family of plastics and in the many, many dif ferent uses to which each can be put. The information has been gathered together in full awareness that the dynamics of the plastics industry can always lead to change both in materials and markets. Photo credits: Cover--Bell Telephone Labora tories; p. 3--Upjohn Co.; p. 9--Union Carbide, Ampacet; p. 10--Bethlehem Steel, PPG Indus tries; p. 18 (top to bottom)--Monsanto Co., RP/C Div. of SPI, W. R. Grace Co.; p. 20--Durez Div. of Hooker Chemicals; p. 21--Eastman Chemical Products, E. I. du Pont de Nemours & Co., Inc., Union Carbide Corp., Carbon Prod ucts Div.: p. 22--Upjohn Co. (top), OwensCorning Fiberglas Coro, (center); p. 25--Gen eral Electric Co. (top), Geoffrey Clements (left), Container Corp. of America (right); p. 26--The West Bend Co., PPG Industries; p. 29--BorgWarner Chemicals; p. 30--Eastman Chemical Products, Owens-Corning Fiberglas, General Electric Co.; p. 31--Celanese Plastics (top), Rohm & Haas (bottom); p. 33 (clockwise from top)--Owens-Corning Fiberglas Coro., Dow Chemical USA, Eastman Chemical Products (cooler); p. 34--Chromcraft Furniture; p. 35-- FCM Div., Gulf & Western (top), General Elec tric Co. (center); p. 36--Rohm 4 Haas; p. 37-- Phillips Petroleum Co.; p. 38--B. F. Goodrich Chemical Co.; p. 40--E. I. du Pont de Nemours 4 Co., Inc.; p. 41--Uniloy-Springfield; p. 43-- HPM Corp.; p. 45--HPM Corp. (top), Somic Ltd. (center, left), Adell Plastics (center, right), Uniloy-Springfield/Pacific Pools (bottom); p. 46 --McNeil Femco, Div. of McNeil Corp.; p. 47Union Carbide Corp. (bottom); p. 49--E. I. du Pont de Nemours 4 Co., Inc. 52 22586054 Educational Facilities Each year more schools, colleges and uni versities are adding instructions in plastics to their curricula. As interest grows, new courses are added, old courses realigned to better prepare students for the needs of the plastics industry. Trade Publications and Books A wealth of information is contained in trade and technical magazines and tech nical books for and about the plastics In dustry. A listing of these publications is available. Speakers Bureau The Society of the Plastics Industry, Inc., has a Speakers Bureau with a number of speeches and slide presentations. Addi tional information and a list of the speeches and slides, with a brief descrip tion of content, is available. For these lists write to THE SOCIETY OF THE PLASTICS INDUSTRY, INC. Public Relations Department* 355 Lexington Avenue ` New York, N.Y. 10017 *,}&?; - ' '3T: . Printed In & bG2^2V