Document 854kpn54eoJ2kvZJXZNkE7NVd

BUSINESS CONFIDENTIAL *./. ti/nec/c*L Sc. PROJECT REPORT PYROLYSIS OF POLYVINYLCHLORIDE HASS SPECTROMETRIC ANALYSIS MAY 15 1975 *N- Wheeler. jr. AUTHORS: J. W. Lewie DATE: April 30, 1974 PROJECT MO.i 22OHO5 supervisor: f. g. Willeboordse PILE MO.: 4030 SUMMARY Analytical examination of the fumes liberated upon heating KDA-2558, vinyl pool liner, and QSAH-7 PVC suspension resin was carried out via Pyrolysis/Gas Chromatography/Mass Spectrometry techniques. At temperatures as low as 175C (low end of fabrication temperatures) hydrogen chloride and benzene are detected. No liberation of any polymer additives to the vapor phase was observed at the 100 ppm level. Neither were vinyl chloride nor phosgene detected at this level. . However, a number of aromatic and aliphatic compounds wer detected and identified, mass spectra of which are shown this report. All samples exhibited charring. Research and Development Department Chemicelt end Plastics Union Carbide Corporation UCC 065250 RECEIVED t R & D TECH. RPT. CTR. INTRODUCTION It has become increasingly important to understand th behavior of our resins when they are thermally treated in fabri cation and processing. Our customers have increased their in quiries to us about the volatile products, mists, aerosols, etc. that are occasionally observed when fabricating resins into finished products. They apparently are feeling the pressures of 0SI1A and EPA requirements. This research was funded by Mr. H. R. Guest in South Charleston, West Virginia through Dr. W. B. Ackart. It was only after this study was completed that great concern mounted in the vinyl community over vinyl chloride and angiosarcoma. W hope to define vinyl chloride's presence or absence in future degradation studies with much greater accuracy. For a comprehensive review on PVC degradation prior reports should be consulted1 2which cover the literature to June, 1971. The experimental parameters regarding thermal treatment were defined for our work in the study conducted by Dr. B. L. Joesten2. RESULTS AND DISCUSSION KDA-2558 The pyrolysis of KDA-2558 pool liner resin was carried out at 175C and 225C for a duration of 300 seconds. The major products of degradation are hydrogen chloride and benzene. The total ion current output and limited mass searches for ions at m/e 36 and m/e 78, diagnostic for hydrogen chloride and benzene, are shown in Figure 1. Air from the pyrolysis chamber is also observed and not resolved from the other gaseous constituents on the OV-1 column. This could be rectified by switching to a porous polymer stationary phase. The mass spectra for the benzene and hydrogen chloride are shown to illustrate minor components that are chromatographed simultaneously with the aforementioned constituents (Figure 2). Although this formulation contains stearic acid (B.P. 358-383C) and dioctylphthalate plasticizer (B.P. 231C at 5 mm) no evidence of their vaporization and transfer to the GC/MS was noted. Presumably their high boiling point prevents liberation to the vapor phase - this could be verified by thermal methods, .g., weight loss curves on each of the two components. O'Mara3 1. a. J. W. Lewis, "Polymer Degradation and Pollution; Analytical Techniques - State of the Art*, October 12, 1971; File No. 3019. b. B. L. Joesten, "Thermogravimetric Analysis; Volatile Products from Polymers", 10/12/71; File No. 3020. 2. B. L. Joesten, "Thermogravimetry: Process Fumes from Polyvinyl Chloride Products", 9/18/72; File No. 3809. 3. M. M. O'Mara, J. Pol. Sci.: Part A-l, Vol. 8, 1887-1899 (1970). UCC 065251 -3- has studied the high temperature pyrolysis (600C) of PVC and Plastisols but no low temperature studies were performed. As expected, degradation of the plasticizer occurs, however, complete account for the chlorine is made without observation of vinyl chloride. Mo evidence of phosgene or vinyl chloride was found although our study was not designed to monitor these compounds specifically. Limited mass searches were made using diagnostic i ns, m/e 62 (for vinyl chloride) and m/e 63 (for phosgene). They are also present in aromatics to a minor degree and while limited mass searches indicated the presence -of this ion, it was associated with the aromatics present. Figure 3 shows mass spectra of the aliphatic compounds which were present. They are low molecular weight, unsaturated and oxygenated compounds. QSAH-7 stabilized QSAH-7 (Polyvinylchloride Suspension Resin) is used as a dry blending resin for calendering, molding and extrusion applications. Specifications indicate that less than 50 ppm of residual vinyl chloride monomer should be present for resins made by the suspension process. The resin is stabilized with 1% organo tin compound, TM-831. Suzuki4 et al have studied the role of tin and zinc stabilizers in PVC and PVC plastisols at 350C to 570C. Zinc stearate drastically reduced benzene yield by entering the backbone of the polymer and forming cross-linked structures through the chlorine moiety. Tin stabilizers did not reduce the benzene yield. This resin was in our possession and exposed to the atmosphere for many months prior to.pyrolysis experiments. Since the B.P. of vinyl chloride is -13,9C, loss of monomer may have been extensive, however, initial residual monomer measurements were not made. The primary degradation products when QSAH-7 (stabiliz d) is heated between 175 and 225C in air are hydrogen chloride and benzene. This is independent of pyrolysis duration. One does observe a variation in the minor products when longer pyrolysis durations are used and this fact may be related to the catalytic effect of the organo tin compound used to "sta bilize" the resin. At a 10 sec. heating duration aromatic com pounds such as indane and anisoles are observed. (Prior workers have observed indanes.) At 180 seconds duration aliphatic compounds are observed as are indications of organic acid and aliphatics, (See Figures 4-7) 4. M. Suzuki, S. Tsuge and T. Takeuchi, J. Pol. Sci.t Part A-l, Vol. 10, 1051-1060 (1972). UCC 065252 -4- Ho evidence for phosgene or vinyl chloride was observed upon searching for characteristic ions in the mass spectra. Limited mass searches were performed using diagnostic ions. This was done after the initial experiments were performed in which chromatographic conditions were less* than ideal.) A porous polymer will be used as stationary phase rather than OV-1 in future experiments. Limits of detection were approximately 100 ppm due to electron multiplier deterioration. A new multiplier should permit examination at 1 ppm level for vinyl chloride. QSAH-7 Polyvinylchloride resin without stabilizer was examined in a manner analogous to stabilized resin. Again, the major products are hydrogen chloride and benzene (Figure 8). There is evidence of tetrachloroethylene (also observed in stabilized resin) by virtue of a molecular1 ion at m/e 164, a four chlorine isotope distribution and fragmentation pattern consistent with the above compound (Figure 9). Perhaps vinylidene chloride in monomer could be its precursor. It appears that beneath the HCl and benzene peaks, there is some m/e 60 ion indicative of acid. Several aromatics are present one of which is naphthalene (see Figures 10 and 11). The data suggests that.the sample size, contact time r duration of heating as well as the temperature may influence the minor side reactions. But primarily dehydrochlorination is the main mechanism of degradation with subsequent cleavage and cyclization to aromatics of the unsaturated chains. The stabilized and unstabilized PVC are similar in degradation at'the tempera tures studied. J. W. Lewis JWL:kmd Attachments (Appendix 1 and 2; Figures 1-11? Table 1) UC0 065^53 APPENDIX 1 INSTRUMENTATION: I. II. III. IV. Pyroprobe 100 - Chemical Data Systems Pyrolyz Controlled Atmosphere Chamber - CDS 820 Varian Gas Chromatograph Finnigan M1015C Mass Spectrometer CONDITIONS; I. * / Interface: 100-225C Ramp; off Pyrolysis; 1C increments 175 -225 C Interval: 180-300 seconds II. Injector; 200C Oven: 205C Trap: Max. 150C Trap Manifold: 205C Line: 205C Helium: 40 cc/min. Air: 40 cc/min. III. Column: 6 ft. Glass, 3% OV-1 on Chromosorp W Injector: 190C Helium Carrier: 40 cc/min. IV. interface: 150C Transfer line: 150C Manifold: 110C Electron Energy: 70 eV Emission Current: 500 y Amps Ion Energy: 7 V Pressure: 10-6 - 10"5 Torr UCC 065254 DESCRIPTION OF RESINS A. KDA-2558 QYNA DOP EPO Advastab BC-103 Atomite TiO, Stearic Acid APPENDIX 2 Pool Liner 55.8% 29.8 2.8 1.4 6.0 4.0 0.2 B. QSAH-7 is used as a dry blending resin for calendering, molding and extrusion applications. It is a suspension process resin. Dry Blend Trial - time to dry 7 minutes, maximum 90C C. QSAH-7 1% organo tin stabilizer, TM-831 IJCC 065255 Experiment M1311 M1311A H1309 M1309A M1266F M1266E M1266A M1266B TABLE I PYROLYSIS DATA ON POLYVINYLCHLORIDE Identity Sample Pyrolysis Temperature C Duration seconds QSAH-7 UNS QSAH-7 UNS QSAH-7 1% STAB QSAH-7 1% STAB KDA-2558 KDA-2558 QSAH-7 1% STAB QSAH-7 1% STAB 1.5-2 1.5-2 30 30 2.2 2.2 0.8 1.0 175C 225C 175C 225C 175C 225C 225C 225C 180 180 180 180 300 300 10 10 Interface C 100 100 175 225 Ambieift 200 200 200 150 140 150 140 100 100 225 200 065256 Oo FIGURE 1 KDA-2558 A. 8. rtK IO* MB C. nv im e-K ucc 065257 A. HCl lOfl 0.1 FIGURE 2 Mass Spectra A. BC1 B. Benzene titlei ma*s kk:a *.sfl=s ci: <r>ccrr.t*i Hunan'.* 3a - 9* total ion ctrr.ncm mswa B. Benzene u ns e SreCTRH MJflEH 77 #> l'* I__ I I* "I1 1 T".....I "l,l " "I " iee ue is ub i ib FIGURE 3 Mass Spectra of Aliphatics (KDA-2558) ffECUUI MfSR 79 ucc 065260 x H1309R Q9FH-7 1m STFB HFflCH 11,1971 225 CEB* C B ucc SPEOPII1 NltfER 363 g M126GA QSftl SlflB. 1* *m-e ucc 065262 I spenrui nlmeu sst maam asm* i stfb hfpw ii.utm zzs deb. c B FXGUHB 7 H**a Spectrum of Components from QSAH-7 stabilised 8j 8 P P bs. k * 58. 8. | * * 4 Lr^ JUW.iiiliiiilii..,-- 18 35 98 10 98 98 78 SB 98 188 118 135 T 198 Tli"e,,T1"98r',7nm T.... 178 188 198 ns E ucc 065263 nww Total Ion Carront CD _ -fCcvboDni Or^\' jPGCQUI WflBl 2M roan osm-7 ueim. tm- tz to*> its ceb B nconB Mass Spaetrua 244 ntnchlnwthrlnt n/ C ISO 110 120 130 1* ISO 160 170 100 130 210 220 230 210 2S0 2B0 rm sPEnuiMHnm rtcure to Oo SPECTFU1 NUM3EB 338 8 mail qsfh-7 iwsrmB. mrr. 22 top its deb FIGURE 11 Mass Spectrum 338 Naphthalene