Document gbdQ71p38Lwvn710MLnb5rbBG

.ri/ls tma or smtcmne or chlorinated vthtl polxhibs ou stone evolution ...... BI , W*l J.Quim, David H. Ahlltrcm, and Shirley A. Llabman . Research and Development Center ^Armstrong Cork Company, Lanealter, Penniylvaoie 1760k Recent report* have appeared concerning pyrolytic gas chromatographic todies for a aerie* of polymers, including halogenated vinyl polymer*.3*3 . However, few worker* have related polymer structure and pyrolysis studies to Snoke. Our Interest in this thermal degradation of chlorinated vinyl poly ner* has lad us to a study of polyner structure and the structural relation ships of the decomposition products produced upon burning sod their subse quent snoke evolution, V# have attracted to answer certain questions. Including! (a) Hhy do certain vinyl polyner* evolve increasing amounts of saokc as the anount of chlorine la increased? (b) Docs tbe structure of the polyner being chlorinated have any effect on evolved smoke? (e) la there an optiaua chlorine content at which in la reduced? To answer the above questions it was necessary; (1) to'deaonatrate that the major pyrolysis products froa the thcraal degradation of a vinyl polyner can be related to the smoks evolved fron that polyner; (2) to deranstntc - that total chlorine content of a polyner Is less significant as regards fire retardancy and snoke generation than the structural location of the chlorine atom on the polyner chain; and (3) to provide infornation and insight regard ing amoke-evolution properties of chlorine-containing vinyl polyoers. To attain the above objectives, four oolyraer systems were studied: polyethylene (PE), chlorinated polyethylene -PE), polyivinyl enldridel i?VC!, ana chlor inated poly(vinyl chloride! (dPvci. Initially, tnese polymer* were pyrolyxed using gas chromatographic technique and tbe major decomposition products were Identified. Then, the smoke evolution from a series of these polymers was measured using the Rohm and Haas XP2 Smoke Density Chsmber. Finally, rela tive smoke values were determined for these decomposition products using the IIS Snoke Density Chsmber. These data were then used for our evaluation of the effect of structure on the smoke-evolution properties of chlorinated and unchlorinated vinyl polymers. 1. Gas Chromatographic Pyrolysis Studies. Host vinyl polymers decompose thermally by radical fragmentation of the polymer chain.2 ;tany type* of com bustion fragment* have been trapped and identified, boettner and eo-vorker* have analyzed tbe volatile combustion product* of certain vinyl plasties.3 The main decomposition product* art carbon dlnxlde, carbon monoxide, methane, hydrogen chloride, and benxene, which 1* the most abundant Hydrocarbon for PVC. No oxygen-containing compound* were found. The thermal decomposition of PE, CPE, PVC, and CPVC has been studied at the Armstrong Research and Development Center using pyrolytic gas chromato graphy." Representative pyrogrsms for PE and CPE are jhovn in Figure 1. No aromatic pyrolytic decomposition products were found with PE. The components In the 3 peek spikes are a.w-diolefin, a-unsaturated olefin, and saturated paraffin, in order of elution from the columr.. ilass-spectrographie analysis - of the pyrolytic decomposition products of PC has shown that lov-molecultrwaight, essentially straight-chain, fragment* are formed.5 These are esaentially hydrocarbon fuel-type molecules known to produce little or no smoke on burning. Aromatic molecules vere not found and, therefore, the polyner is not expected to evolve appreciable smoke on burning. Substituting a chlorine 'for hydrogen in PE substantially changes tbe decomposition product* and in creases the smoke density. Tsugc and co-worker* have Investigated chlorin ated polyethyler.es by pyrolysis gas chromatography,^ They found that as the chlorine/carbon ratio increased, the amounts of aromatic hydrocarbons, such as benxene, toluene, xtyrene, and naphthalene, increased. At a Cl/C ratio Of 0,th,(C.8S Cl) chlorinated aromatics, such as chloro- and diehlorobeoienes, were found in appreciable amounts while the yields of unsubstituted aromatics were reduced. He have found that PE requires a higher degree of chlorination than PVC before tbe pyrolytic yield of unsubstituted aromatic compounds is 1022 J \ | reduced. PVC la I ' substitution at t , .feme random bloe> methylene groups |. pound formation r { alcohol), poly(v. . products similar j In our rece; ' bars demonstrate, f . a corresponding > !a corresponding c ` of PVC sod CPVC i * . burning PVC la dt | - tlon products, ei ` formation of chi- j ated to Contain t highly ehlorinat burn test). Thl tlon. PVC.eHlcr . amd benxene; ana vss mo decrease ed drop in smoke a higher char yl Structures as co Our studies significant tnou thermal decompoj Is raduetd sign! pounds, ths sook 2. Smoke Studio chlorinated real suspension of re as a availing st as a radical ini for periods up t Chamber was uaei . . ' duced when the t ed and ui.ehlorli pressing k.O a ' were then condl. Bose of ti. resins arc show only a small onfound with tela - when this mater large reduetlor material was t rice content, ? and 2. PVC deveil abaeuration. I the maximum n .-reduce the smcl graphically In eliglitly ohscu . the chlorine c teat. PV: chi is equivalent . polyWinyliden eleted for PY>. total smoke in total anoke is ' .TVft'JW.; Jtasx^.l)i- ni x ACS Div. Polymer Chem, Preprints lU, Aup. 1973 OLI 7320 ! 4 i t