Chlorinated polyethylene pyrolysis

Pyrolysis products of chlorinated polyethylene contain molecules similar to those found in polyethylene pyrolysates and, in addition, compounds similar to that obtained from vinyl chloride (significant amount of HCI). Chlorosulfonated polyethylene typically contains only about 1.5% sulfur, but sulfur-containing compounds such as SO2 can be detected among its pyrolysis products. The distribution of chlorine atoms in chlorinated polyethylene has been investigated using Py-GC [55, 56]. The polymer was considered equivalent with a terpoiymer poly[ethylene-co-(vinyl chloride)-co-(1,2-dichloroethylene)]. The level of specific degradation products such as aromatic molecules (benzene + toluene + styrene + naphthalene), chlorobenzene, and dichlorobenzenes correlates well with the carbon/chlorine ratio in the polymer. 

Pyrolysis GC has been used in the determination of compositional analysis and microstructure of chlorinated polyethylene (CPE). This method utilized specific aromatic compounds which were formed through dehydrochlorination of trimers after pyrolysis of CPE polymers at elevated temperatures. The composition and microstructure calculation was based on the difference between the levels of ethylene and vinyl chloride trimers formed [19-22]. 

Smith, P. B., Composition and Microstructure Analysis of Chlorinated Polyethylene by Pyrolysis Gas Chromatography and Pyrolysis Gas Chromatography/Mass Spectrometry, Arml. Chem. 1997 69(4) 618-622. Niemax, K., GC Analysis of Chlorinated Hydrocarbons in Oil and Chlorophenols in Plant Extracts Applying Element-Selective Diode Laser Plasma Detection, Anal. Chem. 1997 69(4) 755-757. 

Smith, P. B., Composition and Microstructure Analysis of Chlorinated Polyethylene by Pyrolysis Gas Chromatography and Pyrolysis Gas chromato-graphy/Mass Spectrometry, Anal. Chem. 1997 69(4) 618-622. 

This method is valid for polymers containing between 25% and 48% chlorine. The calibration curve for the set versus actual temperature of the pyroprobe is plotted in Figure 9.8. The 700 °C (actual 690 °C) pyrolysis temperature was chosen because the yield of trimers of chlorinated polyethylene was higher at that temperature. The pyrolysis of trimers showed a relative standard deviation below 3%. 

Analytical Chemistry 69, No.4, 15th Feb. 1997, p.618-22 COMPOSITION AND MICROSTRUCTURE ANALYSIS OF CHLORINATED POLYETHYLENE BY PYROLYSIS GAS CHROMATOGRAPHY AND PYROLYSIS GAS CHROMATOGRAPHY/MASS SPECTROMETRY Cheng-Yu Wang F Smith P B Dow Chemical Co. 

Fenimore and Jones (12) report die first of their investigations into the modes of inhibiting polymer flammability. They show that chlorine substituted in polyethylene inhibits by affecting the pyrolysis of the condensed phase, but the pair of reactants, antimony plus a little chlorine, poisons the flame. Bromine is more effective than chlorine because it also poisons the flame. They speculate that halogen seems necessary to vaporize Sb from Sb203. 

The critical values of the mass pyrolysis rate, heat release rates, and water application rates for flame extinction for polymers, are listed in Table 53.14. For the polymers listed in the table, the critical values of the heat release rates do not depend on the generic namres of the polymers. The average critical values of the chemical, convective, and radiative heat release rates are 100 + 7, 53+9, and 47 +10 kW/m, respectively. The critical water application rate required for flame extinction is polyoxymethylene, polymethylmethacrylate and polyethylene with 25% chlorine (2.1-2.5g/m -s)[Pg.913]

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