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Jones. These polymers, therefore, resist hydrolysis and aqueous acid and alkaline environments. Properties Short-time mechanical test results are shown in the Plastics Properties Chart, p. 142. Polysulfone has high tensile strength--10,200 p.s.i. at yield--and stress-strain behavior typical (or rigid, ductile materials. Flexural modulus of elasticity is high --nearly 400,000 p.s.i. at room tempera ture. With increase in temperature, flexural modulus stays above 300,000 p.s.i. to about 320* F. Chemical and solvent resistance. Pol ysulfone is highly resistant to mineral acid, alkali, and salt solutions. Resis tance to detergents, oils, and alcohols is good even at elevated temperatures under moderate levels of stress. For example, specimens have withstood 500 hr. in 2% detergent solution at 140* F. and 1500 p.s.i. stress. Polysulfone will be attacked by such polar organic solvents as ketones, chlori nated hydrocarbons, and aromatic hydro carbons. Electrical properties. Polysulfone's electrical properties are retained over a wide temperature range, up to 350* F., and after immersion in water or expo sure to high humidity. Comparison of electrical properties of polysulfone, poly carbonates, and polyacctals indicate two areas of significant difference. First, the dissipation factor of polyacetals is higher by a factor of 10, compared to polysul fone and polycarbonates. Second, good electrical properties are retained up to 350 to 375* F. for polysulfone, 275 to 300* for polycarbonates, and 210 to 250* for polyacetals. Long-term performance. The value of polysulfone as an engineering material is best measured by its performance under physical stress, at room and elevated temperatures, and over comparatively long periods of time. Creep or elongation under load is a useful measure of such performance. In a comparison of the creep of polysulfone with that of polycar bonate, heat-resistant abs, and polyace tal at room temperature for 10,000 hr. (over a year) at 3000 p.s.i., polysulfone is slightly better than polycarbonate, showing about 1% total strain after a year. Both of these materials exhibit less than half the creep of polyacctal. At 210* F., the creep of polysulfone at 3000 p.s.i. is higher than at room temperature, but total strain is still well under 2% after a full year of such exposure. Polysulfone has a great advantage over polycarbonate at this stress and temperature, whereas polyacetal and abs do not appioach these values. For design use, it is helpful to convert stress-strain information into creep modulus values. These are sometimes referred to as "apparent" modulus val ues, and can be used directly in conven tional design equations to estimate deflections. A plot of creep modulus as a function of time at 72, 210, and 300* F. indicates that creep modulus is essen tially independent of stress up to stress levels of 4000, 3000, and 1000 p.s.i., respectively. As for long-term performance, polysul fone at 300 F. shows about a 10% increase in strength and modulus values, 90% retention of electrical properties, and 70% retention of impact strength. Changes take place within the first two to three months, after which the values remain substantially constant for the remainder of the two-year test period. Polysulfone is recommended for contin uous use in air at temperatures up to 340* F. Changing environmental conditions produce exceptionally small dimension al changes in polysulfone. Equilibrium conditions are reached in all cases where such changes take place, except in thermal cycling tests. The very small dimensional changes, coupled with a low mold shrinkage of 0.007 in./in., mean that close tolerances can be main tained with polysulfone. Applications Present commercial use of polysulfone encompasses a wide variety of applica tion areas. In the electrical and electron ic area, integrated circuit carriers, con nectors, coil bobbins, housings for me ters, switches, and electronic compo nents, and light-fixture sockets and shades are produced from polysulfone. It finds automotive uses in under-the-hood switch and relay bases, as well as electroplated dome-light bezels. The aerospace industry is currently using polysulfone for aircraft-cabin in terior parts because of its self-extin guishing and low smoke-density charac teristics. It is also being used for face shields for astronauts because of heat and radiation resistance. Polysulfone is used in appliances in parts for cofieemakers, humidifiers, high-intensity lamps, hot shaving-lather and hot-chocolate dispensers, color-Tv sets, and kitchen-range hardware. Other applications include shower heads, film for transparencies, and toy-oven win dows. It resists the aggressive environ ments encountered by alkaline battery cases and fuel cell components. Polyvinyls By R. J. Abramowitz*, L. J. Friedmant, and R. V. Lurke" Vinyl polymer:, as * class constitute approximately one quarter of all plastics resins in use in the U.S. Vinyl chloride homopolymers and multipolymers form the largest subgroup, and hold greater than 80% of the markets for the vinyl family Worthy of mention are the polyvinyl acetate, alcohol, and formal groups. The latter two find application in solution coatings The polyvinyl acetate family finds ns heaviest applications in the coatings, adhesives, and paper indus tries, where these polymers are used in water-based form. The acetates gained several of their markets on the basis of specific property superiority over the previously vntrenched styrene-butadiene 'Butintu MinigerPolyrncfi, tCroup LexderPVCj "Induitry Manticr-Polymeri, Ruco Div., Hooker Chemicjf Corp , PO Sox 4$6, River Rd, Burlington, N I 08016, For property data on vinyls, see the Plastics Properties Chart, p. 142. polymers. The polyvinyl alcohols find unique use as water-soluble temporary coatings, soluble films, and as protective colloids in latex manufacture and in paper coating slips. The acetate copolymers and their hydrolyzed alcohol copolymer deriva tives, with vinyl chloride particularly, extend the usefulness of the basic poly mer. The acetates and the alcohols are useful respectively in modifying the processing and adhesion characteristics of PVC. Vinyl chloride polymers have deve loped a broad spectrum of market ap plications through property modifica tion. Such modification can be accom plished through the polymerization route, chain modification with como nomers and termonomers, or by com pounding. Among the major products produced from polyvinyl chloride are pipe, packag ing film and bottles, flooring, textilesupported and unsupported sheets and films for apparel, automotive, mime furnishings, wire coatings, and records. Rigid pvc has shown the highest growth rates in recent years, and in 1971 pipe and conduit had an outstanding record in the face of an otherwise slow industry. Supply-demand For the near term, vinyl chloride polymer will be kept in reasonahir balance with demand, with some de bottlenecking types of expansion expect ed in 1972-1973 before any ma)or new capacity commitments. A continued high growth rate in pipe and favorable rulings on the ecology scene for rigid bottles could tighten the supply situa tion in late 1972 or in 1973. Two ma|or additions were made to vinyl chloride monomer capacity, and a new process has appeared on the hori zon, to potentially rival the oxychlonnation route to monomer. Called the Transcat process, vinyl chloride monom er is made directly from ethane, chlo- 102 19721973 Modern Plastics Encyclopeoia Reprints can woricvoryouu A unique sales tool... at mini-cost. Think of ways you can use re prints from Modern Plastics.* Plan a mailing, tor Instance, using reprints with a letter from the boss. Send them with your monthly statements as envelope stuffers. Or distribute them at your stock holder's meeting. Or at your an nual sales conference. Reprints tell about you, or your industry. Written by top authors In the plastics field, every article Is carefully researched for accu racy and cast In an Incisive, easy to read language. Can't be matched. There's no other sales tool quite like a pub lication reprint and your modest investment Is measured in pennies per copy. Few or many. Need just a few hun dred? Or tens of thousands? No problem. Small amount or large, Modern Plastics' Reprint Staff will handle your order expeditiously and ship them In bulk wherever you want. Phone of write to order. Simply tell us which article you'd like re printed (by phone or mail) and we'll give you an immediate quote. Write to: Reprint Department, c/o Modern Plastics, or phone (212) 997-6424, Easy as 1-2-3 for an effective, mini-cost sales tooll Another service to you from the staff of... Modern Plastics 104 rine, and air. The proceis projects at least U lower materials cost/lb. of product, and has no byproducts, or byproduct disposal problems. Commercial viabili ty, however, has yet to be demonstrated. PVC processes Vinyl chloride polymers are produced by four commercial routes: Suspension polymerization. Monomer droplets arc suspended in water and agitated under carefully controlled tem perature and pressure. The polymerized resin is subsequently dried, blended, and prepared for shipment. The suspension process is used to produce a general-pur pose grade of pvc normally ranging in particle size from 90 to 130 microns. However, finer particle size resins are also produced for specialty applications. Major uses of suspension polymerized pvc are in calendered film; extruded .film, wire coatings, pipe and profile; and molded products. Emulsion polymerization. A colloidal dispersion of pvc particles in an aqueous phase is produced in this process. These particles, approximately 0.5 microns in size, can be utilized directly from the dispersion, or latex, either plasticized or unplasticized, or they can be spray dried to a powder for use in plastisols, rigidsols, plastigcls, or organosols. Processes utilizing pvc dispersion resins include slush molding, casting, dipping, spray coating, roll and knife coating, and rotational molding. Bulk polymerization. A more recently developed process is carried out in specially designed reactors in the ab sence of water and suspension additives. Because bulk resins are polymerized in a monomer matrix, the unused portion of which is recycled, they in no way contribute processing residues to the environment as pollutants. While capa ble of producing both general-purpose and specialty types of pvc, the bulk or mass polymerization process can also produce very porous pvc, the structure of which differs considerably from resins polymerized via suspension. Because pvc particles polymerized in bulk are free of additives used in suspension and emul sion polymerization, they lack membra nous coatings. The absence of these pericellular membranes permits bulk pvc particles to fuse very rapidly in minimum work processing situations. Similarly, the excellent clarity inherent in bulk resins has made them preferred in many transparent product markets, including packaging film, bottles, and coatings. Solution polymerization. A process of lesser commercial importance than the others discussed has been utilized in preparing specialty copolymers and terpolymers of vinyl chloride. Polymeriza tion occurs in an organic solvent which then must be usually removed and recovered. The solution polymers are generally higher priced and used in product applications such as coatings and adhesives. Almost always pvc requires corn pounding before processing, but this step permits an unusual range of properties. It is this ability to vary properties so widely that has contributed to several rebirths of growth in the pvc industry. The additives used in pvc compounds may include stablilzers, plasticizers, lu bricants, impact modifiers, processing aids, fillers, pigments, uv absorbers, and viscosity depressants While compounds of pvc differ with respect to product application require ments, they also differ in additive make up to meet these requirements. Thus, a flexible garden hose will require a plasti cizer for flexibility, whereas a rigid pipe will not. A pvc bottle willcall for impact modifier, while a slush molded boot will not. Clear pvc packaging film will, of course, contain no fillers or pigments. Each additive is selected for a specific purpose. Stabilizers keep pvc from degrading while exposed to heat during processing, and protect the polymer against degrada tion in use resulting from heat, light, oxygen, etc. Stabilizers are usually com posed of organo metallic salts, primarily tin, lead, barium, cadmium, calcium, and zinc compounds used in coniunction with epoxides, chelators, antioxidants, etc. Generally rigid pvc is formulated with tin and, occasionally, with lead compounds. Flexible pvc compounds are frequently stabilized with liquid or solid barium-cadmium systems. Nontoxic products are usually stabilized with dioctyl tin or calcium-zinc stabilizers. Plasticizers are added to pvc to impart flexibility to finished products. Phthalate esters are considered to be the workhorse plasticizers. There are many suitable plasticizers, and special types may fulfill specific functions such as improving the rate of fusion, improving low temperature strength, resisting ex traction by soapy water or other chemi cals, and improving flame resistance properties. Epnxidized soybean, linseed, and tallate oils serve as pvc stabilizers as well as plasticizers. Usually more than one plasticizer is used in compounding pvc when properties in addition to flexibility are required in the finished product. Lubricants, processing aids, and im pact modifiers are used in pvc to improve specific properties. Lubricants such as waxes, esters, and metallic stearates are generally compounded with pvc to facilitate melt flow during proces sing. Internal lubricants compatible with pvc reduce intermolccular forces be tween polymer chains, while external lubricants such as polyethylene or min eral oil migrate to the surface of the pvc compound and improve slippage be tween the compound and the metallic surfaces of processing equipment. Processing aids similarly improve melt flow and increase homogeneity within the resin additive package. Impact mo difiers such as chlorinated polyethylene. abs, and mbs reduce the brittleness of unmodified rigid pvc. Fillers are used in pvc primarily to ContinueJ on page ftW 1972-1973 Modern Plastics Encyclopedia 7(1 frif fi'Hlli'f1 ^ EC4522 lower the cost of the compound. In some products fillers perform additional func tions. Both glass and synthetic fibers will Mtsc the impact strength of rigid eve. Asbestos is reinforcing, and reduces shrinkage in floor tiles. Clay gives good tlcctrical properties in wire compounds. Some fillers are abrasive and tend to scrub metallic surfaces during proces sing of pipe and profile compounds. Several of the most popular fillers in clude calcium carbonate, talc, clay, wollastonitc, mica, asbestos, and glass heads and fibers. As a possible substitute for all or some of the compounding normally done, one producer is preparing pipe compounds in situ during polymerization. All of the compounding additives are reportedly being introduced into the pvc reactor or slurry tank. This brings about a uniform distribution of materials previously only obtainable through high-shear, intensive mixing. Cost savings appear probable through elimination of additional prepa ration steps, equipment, and labor. Bulk handling, blending, and storage are facili tated by the process. Success of this approach could have important effects on piocessing equipment needs. Processing Calendering of pvc film and sheet continues to be the most popular route to large volumes of this product form. Ribbon blenders customarily mix the compound, which is subsequently fed (tom a Banbury mill to a short barrelled rairuder and then to the calender. Production rates are high. Aside from homogenizing the molten compound, the extruder screens out foreign matter that might damage the costly calender rolls Thin gauge nontoxic rigid packag ing film is calendered as the preferred route for high quality end uses Vinyl wall covering prepared by calendering has shown continued market strength. In extrusion, compounds based on pellets or powder arc being used in flexible, semirigid, and rigid applica tions Twin- and four-screw extruders of icceni vintage are currently producing large volumes o( pipe and conduit from powder New high efficiency tin stabiliz ers have made the economics of multiscrew extrusion more attractive. Single 'vtiw_ 2a 1 L/D machines are still used m pioducing blown film and flat sheet sia a slot die Rigid pvc foam profile is being extruded for campers and mobile homes Similarly, foam molding strip is mov mg mm other areas. Inuctmn molding of pvc has seen growth in both rigid and flexible pro ducts Reciprocating screw iniccuon molding machines aie turning out shoe 'oles, door tarns, and decorative parts for appliances. Uses of pvc have continued t" grow, particularly in the area of iniection molded pipe fittings in sizes as weal as 10 in. in diameter. Telephone hand sets have been made of high impact grades ol rigid pvc. Improved compounds and resins coupled with increased de mand for flame retardancy are beginning '97? Iq73 MnHnrn Plnnlim Cwnv-- There's new a worry about contamination when you use flexible vinyl compounds supplied by Colorite Plastics Co. That's why Colorite is.a major supplier to so many manufacturers of medical and food-grade tubing, crystalclear parts and other high specification products. Colorite custom develops vinyl compounds for the extrusion and molding industry. Backed up by an enviable reputation for consistent quality, fast service, dependability, technical know-how and realistic pricing. We'd appreciate the opportunity to help you solve your PVC extrusion or injection-molding problems. Write or call. C@L@Ki[IE PLASTICS COMPANY Oept.U 101 Railroad Avenue, Ridgefield, N.J. 07657-Phone (201)941-2900/(212)947-1182 (C) 1972 0rt Induslnti, Inc AH ngMt rtxtrvet). Circle 71 for reader service Clrcln T? Mr rnndrr nnrvlcft EC4523 to quicken application development in this area. Blow molding equipment of compara tive recent development has improved the competitiveness of eve as a packag ing material. There are now a number of suitable machines to choose from. While some fear of unfounded ecological emo tional reaction persists, favorable pro duct protection and consumer accept ance data have encouraged growth in the rigid bottle field. Improvements in res- Polyurethane Urethane polymers can take many forms --coatings, adhesives, elastomers, cast ings, foams, and spandex fibers--yet, they all have one thing in common: they contain urethane linkages, formed by reacting an isocyanate with a compound containing hydroxyl groups. Among the areas in which significant growth has developed for polyurethane arc coatings and elastomers. As protec tive coatings, urethane is versatile of application and has excellent physical properties. The elastomers are replacing natural and synthetic rubber, plastics and even metals, where their superior toughness, abrasion resistance and elas tic modulus can be used to great advan tage Urethane coatings* The growth of urethane coatings has been impressive. In I960, an estimated 6 million lb of urethane coatings were consumed Ten years later, polyurethane consumption was almost ten times that amount and growing steadily at an estimated rate o( 12 to 157, per year. Table I gives a recent breakdown of urethane eoating consumption according to various markets. Also shown is the anticipated growth within these markets protected to 1975 This impressive growth, both past and future, is due to the versatility of the urethane reaction and to the case and rapidity with which it takes place Urethane coatings can be tailored to meet the most demanding requirements of a customer. Urethane coatings arc classified ac cording to the scheme shown in Table II. The oil modified urethane was the early leader in volume growth and still ac counts for the largest volume among the five types However, it is generally conceded that moisture cured and polyol cured prepolymers, Types 2 and 5, are growing fastest and will probably outdis tance the oil modifieds because of their belter properties Within ihe last few years, a sixth type 'Br Alvin Lcincr. Minini-i, Ntw Pinduct Drvclivpmtni. N. .[HChi-mital I Si v Diamond Shamrock < ht-itmvl to, IIS Schuyler Ave, North Arlington, N | 0711)2 For properly data on polyurethane, see the Plastics Properties Chart, p. 142. ins, compounds, stabilizers, and proces sing aids have paralleled equipment development. New developments Producers of rvc continue to predict maior future promise in construction for rigid applications, like rain systems snd siding, and also in carpet backing, pow der coatings, and foamed profile. New offerings were made in each area during the past year. of urethane coatinf has appeared which seems destined for tremendous growth. This is the thermoplastic urethane lac quer which, unlike the other five types, does not depend on an isocyanate curing reaction to develop maximum properties but rather on hydrogen bonding phe nomena. These secondary bonding forces are so great that the physical properties of these films surpass those of most true vulcanizates. At the same time these materials can be processed like any thermoplastic and can be dissolved, heat sealed, calendered or extruded. They are finding wide use as adhesives, fabric coatings, elastomer overcoatings and industrial films. By coating a nonwoven in a special way in production, an artificial suede which is virtually indis tinguishable from genuine suede can be produced. Another use is to overcoat the urethane bumper on the Oldsmobile Table 1. Urethane coating consumption (millions of lb.) Trade sales {clear wood finishes) Industrial maintenance, including flooring Wire coating Leather finishes Fabric coatings Other 1970 21.5 19.5 2.5 3.5 3.0 5.0 Total 55.0 197S 27.0 24.0 4,0 5.0 25.0 6.0 91.0 Table II. Polyurethane coating types Oi< package Two package ASTM-1, oil modtfied AS i M-2, moisture cure A$TM-3, blocked isocyanate Thermoplastics ASTM-4, catalyzed prepolymer ASTM-5, polyolprepolymer cure Prepolymercurative Hybrids Rallye 350 with a coating which color matches the rest of the car. During the past year, growth in urt thane coatings has been propelled by developments in the following areas: Light stable isocyanates. Light-stable isocyanates are finding their way into commercial products which claim 1000 hours of fadeometer resistance to du coloration. Fire retardancy. Several halogenated diols have appeared within the past few, months which arc designed lor incorpo ration into urethane formulations. The government has developed a fire-rctatJ ant paint that is claimed to retain its ability to intumesce fot more than If months. Flame-spread rating of surfaces coated with this paint is 25. Improved hydrolytic stability. Once the bane of many polyester based ure thane coatings, hydrolytic stability has been greatly improved because of a greater understanding of the factors contributing to hydrolytic instability and to use of test procedures which mote clearly reflect in-use conditions. Solventless coatings. Based on short and moderate chain length polyols, sol ventless coating formulations have been commercially applied in seamless floor ing and fabric coating. The ecological and economic advantages of this ap proach are self-evident. Emulsions and water soluble lac quers. These materials also have ecologi cal and economic advantage',. The emul sions can be prepared by inverting an isocyanate free, solvent based system to the water phase. Water soluble ure thanes can be prepared by introducing hydrophilic groups into the polymer molecule. Textile and leather finishes are common applications for such pro ducts. They are also being evaluated for electrostatic coatings. UrcthiiiiL- hybrids. The combination ol urethanes and other polymers oHets unlimited possibilities. Work has been reported on polyisucyanate cured hydroxylated acrylic resins, urethane-mela mine copolymers and urethanc-cposy copolymers. Urethane coatings, especially the light stable ones, are relatively high in price Within a short time, however, the availability of new isocyanates will make light stable coatings available at prices approximating that of current TDI based systems. Such developments will insure a high growth rate for urethane coatings. Urethane elastomerat Urethane elastomers compose a rela tively minor portion of the urethane market compared with urethane foam materials. While their growth has been less spectacular, development has pro gressed steadily and a wide range uf materials, fabrication processes, and ap plications are available. Basically, urethane elastomers are the reaction products of polyesters or poly- fHy III NuhnU, Ljlwtfrfiitfy Mangel. Nifiorhriii nl IN*, MuiHMiiJ SlMiiiiikk ( hrumdl l`ti, Si'huyici Avc , Nnith Ailmjttmt, N | O'MJ EC4524 110 197? 1973 Modorn Plastics Encyctoped'*