Document 8R8ovepEJkLLMwObGx1p2jzXe

April 30, 1990 TO: VI Health, Safety and Environment Committee R:E SPI Filina/TSCA Section 8(&\ The enclosed "Report on Encapsulation of Lead Chromate Pigment in Plastic Resins Relative to the Workplace Hazardous Materials Information System (WHMIS) Classification" has been submitted by SPI to the EPA pursuant to the requirements of TSCA Sec. 8(e). MNS/pmb Meredith N. Scheck Assistant Director CTL019155 Wayne Interchange Plaza II 155 Route 46 West Wayne, NJ 07470 (201) 890-9299 Fax #(201) 890-7029 The Society of the Plastics Industry, Inc. 1275 K Street. N.W., Suite 400 Washington, D.G 20005 (202)371-5200 FAX 371-1022 RK'D APR 1 6 ,^90 Hugh Patrick Toner Vice President Technical Affaire April 12, 1990 Document Processing Center (TS-790) ATTN: 8(e) Coordinator Office of Toxic Substances Environmental Protection Agency 401 M Street, SW Washington, DC 20460 vo ~o -T3 no RE: Lead Chromate Pigments in Plastic Resins Relative to WHMIS Classification Enclosed pursuant to section 8(e) of the Toxic Substances Control Act (TSCA) is a copy of: Report on Encapsulation of Lead Chromate Pigment in Plastic Resins Relative to the Workplace Hazardous Materials Information System (WHMIS) Classification This letter is intended to inform the agency of the findings reported therein. We understand that members of SPI might rely on this letter to satisfy any obligations that they might have to submit this information individually under section 8 (e) of TSCA. The enclosed report was mailed to members of the SPI (US) Occupational Health and Environmental Issues Committee March 22, 1990. It was also the subject of a presentation to the Committee on April 5, 1990. The report indicates that under the conditions of the test, lead chromate was extracted from plastic resin pellets containing lead chromate pigment. CTL019156 Page 2 April 12, 1990 SPI is a trade organization of more than 2000 members representing all segments of the plastics industry in the United States. SPI's operating units and committees are composed of resin manufacturers, distributors, machinery manufacturers, plastics processors, moldmakers, and other industry-related companies and individuals. Founded in 1937, SPI serves as the "voice" of the plastics industry. Sincerely HPT:tmc Enclosure a:\coor leadchro.epa CTL019157 REPORT ON ENCAPSULATION OF LEAD CHROMATE PIGMENT IN PLASTIC RESINS RELATIVE TO THE WORKPLACE HAZARDOUS MATERIALS INFORMATION SYSTEM (WHMIS) CLASSIFICATION PRESENTED BY GJ*. ROBSON ENVIRONMENTAL SCIENCE DUPONT CANADA INC. <) O -n vo ro - CTL019158 report on encapsulation of lead chromate pigment jy PLASTIC RESINS RELATIVE TO WTfMIS CLASSIFICATION INTRODUCTION The attached report was presented to the SPI Canada Ad Hoc Group of Manufacturers of Concentrates and Compounds on 1990 February 20. The information contained in the report was developed at the request of the Ad Hoc Group in an attempt to shed light on the WHMIS status of "encapsulated" hazardous ingredients in ptasuc resin concentrates or compounds, using lead chromate pigment as a model. This was needed to decide whether workers could be exposed to lead pigment during anticipated use of lead chromate-pigmented plastic resins. The Ad Hoc Group arranged for the manufacture of the pigmented resins, the supply of the regrind materials and data from acid extraction tests. My responsibility has been to arrange for electron microscopy and photon spectroscopy and to interpret the results. At the February 20 meeting, we all recognized that although the data developed provide an incomplete picture of the overall situation, and there is no will to continue the investigation at this time, they may represent an important change in our understanding of the availability of additives in plastics resins versus the position we have adopted to date. The Group agreed that the report should be shared with SPI (U.S.) in order to inform them and to solicit their comment and feedback on any implications versus the OSHA Hazard Communication Standard. *** CTL019159 1990 Starch 01 ENCAPSULATION OF LEAD CHROMATE PIGMENT IN PLASTIC RESINS AND ITS IMPACT ON WHMIS CLASSIFICATION SUMMARY WHMIS regulations in Canada require that untested mixtures be classified according to the toxic properties of ingredients in the mixture. The Plastics Industry considers that it is unreasonable to apply this concept to plastic resin concentrates and compounds which contain toxic ingredients, without regard for the availability of such ingredients to cause worker exposure. An SPI Canada Ad Hoc Committee of manufacturers of compounds and concentrates proposed that data be developed to provide a better understanding of how toxic ingredients are distributed in plastic resins and their availability to be released and cause worker exposure under anticipated use conditions. Part of that activity involved the preparation and testing of lead chromate pigmented PVC, ABS and PE resins as 3 mm dia. cylindrical pellets. Lead chromate was selected as a 'model* substance since it is commonly used and is a WHMIS Controlled Product - as a carcinogen. Resin pellets were examined by Scanning Electron Microscopy (SEM) and X-Ray Photon Spectroscopy (XPS) to determine whether lead chromate pigment particles were exposeu at the pellet surface or were truly encapsulated in the resin. SEM showed that pigment particles were at or close to the surface but due to the slight surface penetration of the electron beam up to 1 micron it was not known whether they were actually exposed at the surface. XPS provides quantitative information on elements at surfaces and only penetrates monolayers at the surface approx. 5QA. 1 micron is equivalent to 10,000A. XPS showed that the lead pigment concentration at PVC pellet surfaces was similar to the bulk concentration; PE pellets showed traces of lead pigment at the surface. In ABS pellets no lead was detected at the surface since silicate-encapsulated lead chromate pigment was usedSimilar XPS results were obtained from frac tured pellet surfaces which revealed the interior or bulk composition. Extraction of whole pellets in 5% aqueous hydrochloric acid for 10 minutes, using a standard test to simulate stomach add digestion, showed that some lead was extracted in all eases, in approximate proportion to the lead pigment con centration in the resin. The average proportion of lead extracted from whole pellets was 0B8% of the total lead in the resin but the actual levels of lead extracted were below 0.03%.The effect of resin size reduction, eg. as dust, on lead extraction by add,is not known. Assuming thatdust inhalation is the principal workplace exposure route of concern for plastic resins, tests were conducted to measurethe inspirable dust concentration (i.e.<100 micron partide size) in commercial reground resin. Samples of ABS, PVC and HDPE commercial regrind resin (not lead chromate pigmented) contained a maximum of 0.002% dust less ISO microns. Testing of one grade of 5 mm dia. PE resin pellets by rolling in a steel can for one hour to simulate attrition in steel containers or pneumatic conveying lines produced 0.0012% dust less than 177 microns. It is not known how a broad range of plastic resins would rate in evaluating their potential to produce inspirable dust. CTL019160 Several possible ways of using the 0.1% (or 1.0% as appropriate) tration for WHMIS classification of mixtures aresuggested which plasticresins. Some discussion will be required to decide on applicability. minimum concen could apply to their value and Based on these data we should reconsider the use of theterm 'encapsulated" for additives in plastic resins. It is clear that some lead chromate pigment particles are actually exposed at the surface and are not covered by a layer of plastic resin. I suggest the term 'bound* would be more accurate. INTRODUCTION The regulation relating to WHMIS Classification and the use of the arbitrary 0.1% or 1.0% by weight ingredients minimum concentrations for classification of untested mixtures for toxicity and corrosivity, involve the inherent assumption that such ingredients are available in a form such that workers can be exposed to them. Also these cut-off concentrations recognize that ingredients present below these concentration values will not be considered in classifying untested mixtures because they will not contribute significantly to the hazards of the mixture. The concept of hazardous ingredients present in materials to which workers cannot be exposed under anticipateduse conditions is the basis for the exclusion of manufactured articles from WHMIS classification. This concept has not been extended so far to cover materials other than manufactured articles. Commercial thermoplastic resins such as polyethylene, polypropylene, polyvinyl chloride, polystyrene, acrylonitrile/butadiene/styrene copolymers (ABS), and acetals, are tough materials which do not shatter easily under impact or grinding conditions to form fine powders, and which are essentially insoluble in water and body fluids. When such resins contain WHMIS Controlled Product ingredients such as non volatile pigments, fillers, stabilizers or reinforcing agents (fibres), the ingredients are dispersed in the polymer matrix by melt compounding and when resin compound pellets are produced for commercial use, the ingredients are bound firinly within the pellet and are not available in any significant amount to cause exposure of workers to the ingredients under normal use conditions. In order to demonstrate experimentally that non-volatile additives are bound in plastic resin matrices, we must recognize the three human exposure routes for plastics resin ingredients, viz: (i) inhalation, (ii) ingestion, and (iii) eye or skin cootact/absorption. Note: Re Scone of Bound Ingredients Ingredients which are volatile under melt processing conditions to release gases, vapours or aerosols (i.e. small liquid or solid particulates which condense in air from vapour released) are not considered as being bound in the plastic resin. Such ingredients will besubject to the normalWHMIS classif ication rules for untested mixtures, eg. residual styrene in styrene-based polymers. CTL019161 - 3- The following criteria are proposed for additives which can be considered to be bound in plastic resins: 1. Additive has not significant vapour pressure at worst case melt processing temperatures (what is significant?). 2. Additive has decomposition temperature well above melt processing temper atures. 3. Additive can bewell dispersed in the resin, i.e. no large agglomerates exist. 4. Additive does not migrate or diffuse to the surface of resin pellets on storage. 5. Grinding of scrapor reclaim does not liberate the free the additive in a way that can cause harm to workers. additive or expose Note; In most cases all five conditions should be eg. azodicarbonamideblowing agent is a WHMIS used in some resins, but is intended to decompose normal melt processing conditions. met. Exceptions may occur, controlled product ingredient to release nitrogen gas under Skin or eye contact is not considered to be a concern provided that the additive does not migrate significantly to the surface of the resin pellet. For inhalation and ingestion we are concerned primarily with exposure to dust, since pellets will not be ingested or inhaled. Dust can be generated in several ways: i) during resin compounding by manufacturer fines from attrition of pellets during handling, pneumatic conveying and packaging; and dust from grinding of product or grinding of recycle or reject material. ii) during use by customer; fines from handling and pneumatic conveying; and dust from grinding recycle material. EXEEB1 rAL WORK Experiments were carried out: 1. Commercial resin pellets containing lead chromate pigment were examined by electron microscopy, x-ray photon spectroscopy and acid extraction to determine the location and availability of the lead pigment at the pellet surface. 2. Commercial resin pellets containing azodicarbonamide were examined to deter mine the potential for dust production by attrition and release of the free azodicarbonamide ingredient 3. Commercial resin regrind samples were examined t determine the amount of fine dust produced. CTL019162 4- RESULTS 1. PVC. ABS AND PE RESINS CONTAINING LEAD CHROMATE PIGMENT a) Scanning Electron Microscopy of Surface of 3 mm dia. x 3mm long Pellets Scanning electron microscopy (SEM) of resin pellets was carried out to determine if the lead chromate pigment could be detected at, or near, the surfaces. Some pellets were fractured in liquid nitrogen and the fractured surfaces examined to determine if the interior was significantly different from the external surface. Resins containing 33 to 30% pigment (concen trates) and also 2% pigment(compounds) were examined.Since different sources of concentrate were used to prepare the pellets it was found that ABS resin contained silica-encapsulated lead chromate pigment. PE and PVC resins contained non-encapsulated lead chromate pigment The detailed results and copies of the photo-micrographs obtained on the SEM at Queen's University are in Appendix 1. Note that SEM is not a quanti tative technique. In summary the following conclusions were made: i) Lead pigment particles were detected at or close to the surface in all cases. For PE and ABS the pigment concentration did not appear signifi cantly different between the fractured interior and exterior samples. For PVC there appeared to be a greater pigment concentration at the exterior surface compared to the fractured, internal surface. ii) SEM showed pigment particles at or close tothe pellet surface but, because the electron beam penetrates the resin surface to a depth of up to 1 micron, it is not possible to know whether any pigment particles are actually exposed or whether they are covered by a thin (approx. 1 micron) layer of plastic resin. b) X-Ray Photon Spectroscopy of Sorbet of 3 mm dla. i 3 mm loan Pellets X-Ray Photon Spectroscopy (XPS) of resin pellets was carried out at the Surface Science Laboratory of the University of Western Ontario (Surface Science Western). XPS was used because it can examine the outermost surface of materials with penetration only of approx. 5QA (Note: 1 micron equals 10,00QA) and provide quantitative data. The detailed results of the XPS work are in Appendix II. In summary, the following weight %): conclusions were made (all concentrations are i) In the PVC samples high concentrations of lead were detected at the external surface vis 13% in Pb in the 33% lead chromate sample and 3.6% Pb in the 2% lead chromate samples. These levels were reduced by 90% after the measured surface was sputtered, Le. cleaned to a depth of 10QA by the x-ray flux. This indicates that higher levels of pigment are at the external pellet surface. CTL019163 5- - ii) In the PE samples the 50% PbCr04 pellets Pb at the surface. The 2% PbCr04 pellets the surface - at the detection limit of the method. showed approx. 0.5 to 1.0% showed approx. 0.2% Pb at iii) In the 2% PbCrOj in ABS sample, lead pigment was not detected in any surface, at a detection limit of approx. 0.2% Pb (see c) ii)below). There are several inconsistencies in the numerical values for atomic composi- [ion provided by XPS. For example, lead concentrations decrease after sputtering in the PVC samples but increase greatly in the PE sample. It is difficult to explain such effects based on the few samples examined. c) X>Ray Photon Spectroscopy of Surface of Lead Chromate Pigment Used In These Tests i) A non-encapsulated grade of pigment was used for the PE and PVC samples containing approx. 60% Pb. XPS of this pigment showed the surface composition to be: 17.2% by weight Pb 1.9% by weight Cr 13.8% by weight AJ 36%% by weight C 30.9% by weight 0 ii) A silica-encapsulated grade of lead chromate pigment was used in the ABS sample and was also examined by XPS. The surface composition found was: 27.6% by weight 0 35.1% by weight C 23.9% by weight Si 13.4% by weight A1 Lead was not detected. Sputtering of the surface to remove the original surface and re-examina tion did not detect the presence of lead. Therefore based on this limited test, this pigment is clearlycoated with a silicate material which appears to encapsulate the lead chromate pigment entirely. d) Simulated Stomach-Add Extraction of rfld rTinrnutf-Tftrtalnlna Resin* "4 P-- Samples were extracted with 5% aqueous hydrochloric add at 20*C for ten minutes according to the method described by Consumer and Corporate Affairs Canada in the HazardousProducts Act, Part 1, Section 9. Work was done by Technitrol Canada Ltd, Report No. 194363, 1989 August 25. Results were: CTL019164 6- - Sample % Pb in Resin ppm wt. of Pb* Leached Proportion of Total Lead in Sample Extracted bv Acid as 33% PbCr04 in PVC :% PbCr04 in PVC 50% PbCr04 in PE 2% PbCr04 in PE 3% PbCr04 in ABS 2% PbCr04 in ABS Regular PbCr04 Pigment Encapsulated PbCi04 Pigment 19.8 202 1.2 8 30.0 249 1.2 4 1.8 27 1.2 7 60 9400 40 6900 0.10 0.07 0.08 0.03 0.15 0.06 Average of above values * 0.08 1.57 1.73 * ppm Pb is calculated on weight of sample pellets/pigment 2. COMMERCIAL POLYETHYLENE RESIN CONTAINING 0.3 TO 1.0% AZODfCARBONAMIDE a) Dust Production br Attrition of Resin Pellets Resin in the form of approx. 5 mm dia. lens-shaped pellets, produced by melt cutting, was tested to simulate attrition caused by pellets impacting other pellets or impacting metal surfaces such as in bulk containers and pneumatic conveying lines. A one-gallon steel paint can was half-filled with resin and rolled at 60 rpm for one hour. The resin was then screened to measure dust production with results: % weight Through IS mesh and Retained on 80 mesh (177 micron opening) 0.0096 % weight Through 80 mesh 0.0012 b) Composition of Pine Post Produced The particles less than 80 mesh were examined by infrared microscopy. In this method infrared spectra are produced for individual particles. The spectra showed the material to be principally polyethylene with small levels of azodicarbonamide present. Thus the azodicarbonamide (which is a respiratory sensitizer) is bound in the polyethylene resin. Free particles of azodicarbonamide were not detected. CTL019165  7- 3. DUST f\ REGRIND SAMPLES OF ABS. PVr WD HDPE RESIN Samples of resin from a commercial regrind operation were collected directly from the grinder discharge and the size range measured at Queen's University. Results were: % weight retained on sieve Resin \k?ii g-Mtsh Qgf.ning (4 mtq) ABS PVC HDPE 9.6 48.5 41.7 18 Mesh 100 Mesh H mm) Llifl-misnml 89.7 0.65 5U 03 57.6 0.68 Zflfl.Mtth 17 ntarw) 0.0013 Nil 0.002 Less than 200 Mesh Nil Nil Nil Airborne partides which can be inhaled must be less than 100 micron size. This is known as "inspirable* dust (see ACGIH TLV Booklet, App. E). The fraction between 100 micron and 10 micron in size will be deposited in the upper respiratory tract and will usually be swallowed with the mucus. Particles less than 10 micron in size will be deposited in the midrespiratory tract and lungs. The data show that only 13 to 20 ppm by weight of regrind resin is less than 150 micron in size. No detectable quantities of dust less than 75 micron could be measured. DISCUSSION 1. CORRELATION BETWEEN XPS/SEM AND ACID EXTRACTION TESTS The acid extraction test simulates the extraction of ingredients from samples that could occur if the samples were ingested and subjected to stomach add. The data in the Table above show clearly that the amount of lead extracted from resin pellets is proportional to the lead content and also particle size. The surface area to volume ratios for pellets and pigment particles are: 3 mm dia. x 3 mm long pellet volume - 2L2 mar surface area 42.4 mm2 Therefore surface area: volume ratio > 2.1 mn` 10 micron dia. pigment agglomerate volume 0.52 x 10^ mar surface area * 3.14 x 10~* mm2 Therefore surface area: volume ratio - 6 x 102 Note: Selection of 10 micron size for the agglomerate is a simplifying assumption. -1 Therefore pigment partides have a surface area to volume ratio approx. 300 times greater than the pellets. CTL019166 8 - The greater surface area of pigment particles should enhance their solu bility in acid, however, it is not possible to make a direct comparison with pellets due to unknowns such as solubility rate and presence of some aluminum-containing coating on the pigment particles, as indicated by the XPS analysis - see page 5. About 0.08% of the total lead present in pellets was extracted compared to approx. 1.6% for the lead chromate pigment, i.e. a ratio of 20:1 for pigment: pellets. Although the XPS measurements showed no detectable Pb at the surface of the encapsulated pigment and very low to non-detectable Pb levels at the surface of the PE and ABS samples, lead was still extracted from these materials in the hydrochloric add test. Therefore there is no good correla tion between XPS results and HQ extraction test results with respect to the availability of the lead pigment. ARGUMENTS AROUND THE 0.1% INGREDIENT CUT OFF CONCENTRATION PbCr04 present at <0.1% weight in a resin would not be subject to WHMIS regulations. 0.1% PbCr04 is equivalent to 0.06% Pb, anming the material to be PbCr04. Is it possible to demonstrate that the lead in these materials which is in an available form, is less than 0.06% (600 ppm weight) Pb? 1) Composition of Dust from Resin The SEM micrographs show that the lead pigment is at or very dose to the pellet surface. The XPS measurements show that leadpigment con tent of the outermost pellet layer varied greatly with the resin used, being highest for PVC This is probably a function of the dispersibil ity of the pigment in each resin, the melt viscosity characteristics, and the manufacturing process used. It is probable that different results would be achieved with the same nominal composition but differ ent pellet manufacturing techniques. Therefore we cannot extrapolate reliablyfrom these data the pigment content of dust produced by pellet attrition. to estimate Assume that dust has the same composition as the bulk resin. 11) Quaaflty/Ptrrrptagt of Inspirable Dust Plwduced from Resin or Remind Material Data obtained show; Attrition of PE pellets for one hour produced 12 ppm weight of dust less dun 177 micron particle size, L e. inspirable dust. Grinding ABS, PVC and HDPE scrap produced 13 to 20 ppm of dust less than 130 micron particle size. CTL019167 9- - Thus in ail four samples the inspirable dust is well below 0.1% by weight. Therefore, regardless of the composition of this dust, it can be claimed that the 'available' pigment which could cause worker expo sure is wellbelow 0.1% and therefore the material should be excluded from WHMIS classification. The level of inspirable dust produced by a wide range of resins is not known. Therefore the broad applicability of this argument is not known. iii) Percentage of Lead Extracted from Resin bv 5% HC1 In all cases for resins tested by extracting whole pellets with 5% aqueous HQ at 20*C (see Table) the amount of Pb extracted was well below 0.06% Pb (* 0.1% PbCrO^) calculated on a pellet basis. Therefore the 'available* pigment is below 0.1% and provided that this test is anacceptable criterion for extractability, the material should be excluded from WHMIS classification. The extraction level for smaller resin particles and for other formulations is not known, and therefore the broad applicability of the argument is not known. 3. HOW RELIABLY CAN A SUPPLIER PREDICT USES FOR PLASTIC RESIN PRODUCTS? Arguments have been made that the use of professional judgement, in class ifying resin products based on the potential for exposure, is not valid because suppliers cannot understand or predict end uses to which customers may subject their products. This is an important and basic issue which SPI must deal with in a positive manner. Arguments that plastic resin suppliers can reasonably predict end uses include the following: Plastic resins have limited high temperatures for use consistent with preserving the useful, physical properties of the resin. At excessively high temperatures, plastics decompose or depolymerize producing a variety of low molecular byproducts and the hazardous consequences of such high temperature treatment are described on MSDS. Reams are sold in granular form, have particle sizes ranging from cylin drical pellets approx. 1/4* diameter, to spherical beads, to free Sowing powder. Customers may grind resin to produce fine particles for unusual purposes and the adverse or hazardous consequences of grinding ream should be known to the supplier and described on MSDS. Commercial plastic resins are relatively chemically inert and MSDS should describe their chemical reactivity and incompatibility. It is difficult to identify any other end use issues apart from tempera ture, size reduction and chemical reactivity which could apply to plastic resins. If these three topics cover all significant end use be possible to claim that suppliers can confidently using professional judgement to make WHMIS classifications. issues then it should consider end uses in CTL019168 - 10 4. DISCLOSURE OF GENERIC CHEMICAL IDENTITY OF HAZARDOUS INGREDIENTS IN PLASTIC RESINS la cases where the detailed identity and concentration of hazardous ingredients is resins is not disclosed because WHMIS exemption iif claimed, it is recommended that the generic chemical identity of these ingredients be provided so that users may take appropriate precautions in the event of fires, disposal by incineration, contamination of soil or water, etc. CTL019169 APPENDIX I SCANNING ELECTRON MICROSCOPY OF PLASTIC RESINS CONTAINING LEAD CHROMATE Pir.MF.NT A summary of conclusions obtained from SEM photomicrographs is given below. Photographs of the Polaroid photomicrographs are also provided (not included). DEFINITION OF TERMS USED ON PHOTOMICROGRAPHS SEI BSE Pb MAP Secondary Electron Image Surface Topography Back Scattered Electron Image More dense particles at or near surface show up as lighter on back ground Light coloured spot identifies Pb-containing material at or near surface In SEM the electron beam penetrates the surface and causes backscattering. Penetration is a function of density of material and may be up to approx. 1 micron * 10,000 A. CTL019170 - *) . 2%. PbCrO^ in ABS SEM bv Queen's University 1. Cylindrical Surface BSE image shows pigment particles at, or close to, surface and corres ponding to high points on secondary electron image (SEI). Pb MAP confirms that particles contain Pb and correspond to SEI and BSE image. 2. Fractured Surface BSE matches SEI for location of pigment particles. Number of particles is not significantly different from cylindrical surface at same magnification. PbCrO( In PE SEM by Queen's University 1. S0% PbCrO| a. Cylindrical Surface Pigment particles visible at/near surface by SEI and BSE. clusive not exposed long enough (see #1, 2). Pb MAP incon b. Fracture Surface Pigment particles visible at/near surface by SEI and BSE. 'Pits* visible at fracture point where pigment particles were located. Pb MAP inconclusive since not adequately exposed (see #4, 5, 7). c. Flat End oT Pellet Pigment particles visible at/near surface by SEI and BSE. sive. Structures like pits visible (see #8, 9). Pb MAP inconclu 2. 2% PbCrO< a. Cylindrical Surface Pigment particles visible at/near surface by SEI/BSE. particle identification (see #11, 12, 13). b. Flat End of Pellet Pigment particles visible by SEI (see #14). Pb MAP confirms CTL019171 3- PbCrOj in Polvcthvlcnc (PE) SEM bv University of Western Ontario 1. 50% PbCrt)4 Cylindrical Surface Pigment particles visible at or near surface. SEI only. No BSE or Pb MAP made (see photos #33, 34, 35). 2- Y\ ghCr04 a. Cylindrical Surface Pigment particles visible at/near surface by SEL. Pb MAP not very clear but supports identification. High mag. view shows particles bound in resin (see photos #22, 23, 25). b. Fracture Surface Pigment particles visible at/near surface by SEL Pb MAP supports identifi cation. Pigment particles more visible, i.e. at surface, than at cylin drical surface. 'Pits* visible where pigment particles were located (see photos #26, 30). ftCrtU-Ja PVC SEM hr Oneen's University 1. 2% PbCrO| - SEM Cylindrical Sorihce - Sample M High pigment level at or close to surface. Pb MAP confirms BSE location of pigment particles (see #1001, 1003, 1002, 1004, 1005). 2. Appears to be less pigment than at surface. 33% PbCrOj - SEM - Sample N Cylindrical Surface Very high pigment level at or close to surface. view. BSE confirms high pigment at/dose to surface. Some surface occlusions in one CT1,0191*72 APPENDIX II X-RAY PHOTON SPECTROSCOPY OF PLASTIC RESINS CONTAINING LEAD CHROMATE PIGMENT A summary of conclusions obtained from XPS analysis of resins is given in the attached Surface Science Western report dated August 1989. Note: XPS provides quantitative results in Atom % UQt weight %. Atom % is converted to weight % by multiplying atom % by element atomic weight and normalizing these values to calculate % weight by each element involved. CTL019173 X?S Analysis of Plastic Resin Pellets For Dupont Canada Inc. Research Centre Kingston, Ontario By Surface Science Western University of Western Ontario London, Ontario August, 1989 NeTE.: A psw Prepared by: Dr. R. Foerch R.D. Davidson on/ CTL019174 Intrccuctic n Pellets of PVC, PE ar.d ASS containing various levels of lead chromate (PbCrO.) have been analyzed by X-ray photoelectron spectroscopy (XPS or ESCA) to determine the levels of lead actually on the surface of the pellets. Techniques such as IR and SEM have indicated high levels of ?b present on the surface, however both these techniques probe beyond depths of several hundred Angstroms into the sample, thus probing the bulk polymer as well as the surface. XSS, on the other hand probes the first few monolayers to an approximate depth of 30-50 Angstroms. During XPS analysis a sample is irradiated with monochromatized X-rays of known energy causing the ejection of photoelectrons from all elements (except hydrogen) within the sample. The kinetic energy (E__) of the ejected electron is equal to h& ~ EA1 Ka " "* Where E,, -- = energy of the incident photon and ex - binding energy of the electron / ev $a * work function (usually negligible) Thus, by measuring E__, of the photoelectron and knowing E-ij. , E_ can be calculated. XPS provides both qualitative ana^quantitative information on the elemental composition of the sample. Experimental X-ray photoelectron spectroscopy was performed on the polymer pellets using an SSX-100 Surface Science Laboratory X-ray photoelectron spectrometer which utilizes monochromatic Al Ka X-rays for excitation of the samples. The elemental broad scans were recorded using a pass energy of 148.00eV and an X-ray spot size of lOOOum or 600ym analyzing binding energies between 0 and lOOOeV. Samples Al, A2, Bl, B2 and C2 were analyzed on the cylindrical, the end and on a fractured surface. On Al, A2 and B2 the cylindrical surface was sputtered for 2 minutes using Argon to probe deeper into the surface. Bl was sputtered on the fractured surface. Results XPS results have been tabulated in Table 1- and values are given in atomic %. They appear to indicate that when the bulk polymer is PVC, lead is detected even at a CTL019175 concentration by weight of 2%. On the other hand if the bulk polymer was PE, lead is detected at a concentration level by weight of 50%, but is not detected if the concentration level is 2%. However, when the bulk polymer is A3S, no lead is detected. Samples Al, A2, B1 and B2 show levels of Pb on the cylindrical surface ranging from 1.2% to 0.01% which represents the detection limit of XPS for Pb. Upon sputtering the cylindrical surface (Al, A2, B2) for 2 minutes using Argon (to roughly a depth of 100 Angstroms), the amount of Pb very noticeably decreases suggesting lesser amounts of Pb further into the surface. Other elements detected were chlorine, silicon and very low levels of chromium in Bl. Barium and cadmium were detected in sample A2. Analyzing the end surfaces of samples Al and A2, similar levels of Pb were observed as on the cylindrical surfaces. Bl shows slightly more Pb on the end surface of the pellet, while B2 shows no Pb. Fractured surfaces of Al, A2 and B2 show similar levels of lead compared to the cylindrical surfaces. Bl shows a similar level of Pb on the fractured surface as on the outside cylindrical surface. When sputtering the fractured surface, XPS indicates an increased level of both Pb and Cr being exposed from further inside sample Bl. Chromium was also be detected on Al (cylindrical surface) and Bl (end and sputtered fracture). Sample C2 was extremely "clean", showing no Pb or Cr on any surfaces examined, even after sputtering. However, it was noticed that upon sputtering the relative % of N and O on the surface decreased. Otherwise all surfaces showed similar amounts of O and N. SEM Results A series of secondary electron SEN micrographs were obtained from samples Bl and B2. The micrographs are identified on an attached sheet. Table 4. The micrographs clearly show the difference in the pigment loading levels between 2% and 50% PbCrO. in the PE samples. The pigment particle size is approximately 0.5 - l.Oum. The differ nt contrast levels for the particle (from bright white to a faint grey) suggest that the particles are at different depths within the matrix material. Pb X-ray CTL019176 2. mapping was carried out on the 2% PbCrO. sample. The results show Pb, as expected, associated with the pigment particles. Conclusion The XPS results indicate that lead (PbCrO.) is present in small amounts on the surface of PbCrO. doped PVC pellets. Upon sputtering deeper into the surface less Pb is detected. The concentration of Pb on the fractured surface is very similar to that on the cylindrical side, suggesting that the lead is present on the surface. 3 Pb is detected in very small amounts in the PbCrO. doped PE, even for the 50% doped pellets. The fracturld surface shows similar amounts of Pb, yet upon sputtering, the concentration of Pb clearly increases. This indicates that even though some Pb is present on the surface, the majority is deeper inside the sample. In the PbCrO. doped ABS, lead and chromium are not detected on any surface. Recommendations The objective of this preliminary study was to determine if PbCrO. pigment particles were exposed at the surface of the plastic resins. Intriguing XPS results, especially for the PVC samples, suggest that the pigment is concentrated at the surface. Further characterization with XPS and SEM may result in a better understanding of the location of the pigment particles in the PVC. It may be possible to carry out further SEM examination using stereo imaging to determine whether or not the pigment particles are standing proud of the surface. Further XPS analysis on additional samples may aid in this study. For example, XPS analysis of freshly fractured (perhaps cooled to liquid N- temperatures) resin pellets would provide a good 'bulk'^analysis to compare to the extruded cylindrical surfaces. -3 CTL019177 Tabic 1. XPS analysis o PbCrO^ containing polymer pellets sample XC \N io \Cr IPb 1C1 A1 33\ PbCrO, in PVC cylindrical side 82.7 10.1 0.2 cyl. side sputtered 91.5 - 8.1 - endview 86.3 - 12.4 - fractured 79.2 9.7 1.2 5.0 0.1 0.4 1.3 - 1.1 10.0 HOT_ ; -fHase ftrtt in iVt^rUt % isi 1.0 - Ilia - led - -- % urifiuT ri> w IS o I3S A2 2\ PbCrO. in PVC cylindrical Side 78.6 - 9.3 - 0.3 10.4 - 0.8 0.7 cyl. side sputtered 91.2 - 3.4 - 0.04 5.3 - 0.1 - endview 84.3 - 9.1 - 0.2 5.4 - 0.5 0.5 fractured 72.2 4.7 0.1 22.9 -- 0.2 0.1 3-^ oG Dl 501 PbCrO. in PE cylindrical side 97.3 - 2.7 - 0.03 endview 96.1 1.2 2.2 0.05 0.1 fractured 98.7 - 1.3 - 0.05 frac. side sputtered 93.3 0.3 4.5 0.8 0.6 D2 2% PbCrO. in PB cylindrical side cyl. side sputtered endview fractured 99.2 98.2 99.2 100 - 1.1 * 0.85 0.75 0.8 - - - C2 2% PbCrO| in ABS cylindrical side cyl. side sputtered endview fractured 90.3 95.1 92.1 89.1 4.9 2.0 4.6 5.0 4.3 2.9 3.3 4.2 - 0.01 -- " " - -- - - - -- -- - 0.35 0.6 - " ----- ---- 0.5 - ---- 1.8 -- - 0*5T - '7 oa " ^*c> - -- <0-27^ <o'-zimax`t' - -- -- -- <on I NO-i <0 -2. <^0v2 Lvt.lUltJ CTL019178 THE FOLLOWING THREE SPECTRA ARE TYPICAL OF THOSE OBTAINED FOR PbCr04 - CONTAINING RESINS CTL019179 X-flay Powoi: VIHIICAL SCALE 4000 COUm&AMT4l Flood Gun: 1.0 Opnalor: Spot S12Qi GOO u a u I Huso 1 uL 1 uni 4 CUIISOH UIHOING MltllGV # electrons detected 1000. 0 UHl'tll UMIHUIG LIM.IIGV |V| 2---------------- - 'jl AH'. SAMPLE: ......................................... COMMENTS. ..................... LLAULKIJMML 3JZ/ PVL DUci 00036 0/IS/]000 .............. DATE: . DUPUN;JU) DATA FILE f ........ ' Huy I uii 1 lilt* SimIi m i: St h*im n I iImii.iIoi y 11 mi Utiivirr.ily n| < hil.iild <-- liiiullny vnuryy (vV| oTo i owm luiiiiimi i imii.v |C v ||c|oil 0. CTL019180 X-Ray P war: VERItCAL SCALE 4000 minimum Flood Gun: ] . () Operator: pjr Spot SUu, GtiO u lUuioliiL i um 4 cunson mnoing enehqv II i # electrons detected i n *4In a. i 1000.0 J umil DMIIIIHG tlltllGV (V| SAMPLE: ................................................... IMetci ' UGlKiii' DATE: COMMENTS: ............................................................................................ DATA FILE I.IIAiJ CHtlMAU. :>IJX i*l;. aupoMr^my ' t.'urjlnn"1 hliidinrj cuerrjy (oV) o. n iUWI.I| IIWUlMli LMLIUaV |eV| $ ^LAHU IImi SmiI.ii ii *i< loin ii I ri|mmtillmy, ||mi I laiivi*i. I WitMi'in I Ini.mu ||l`|Hll| I CTL019181