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Thermooxidative degradation of poly(vinyl chloride) and chlorinated polyethylene with different Ca/Zn carboxylates

The thermooxidative degradation of poly(vinyl chloride) (PVC), chlorinated polyethylene (CPE) and PVC/CPE blend 50/50 was investigated by means of dynamic and isothermal thermogravimetric analysis in the flowing atmosphere of air. To estimate the thermooxidative stability of the samples the characteristics of thermogravimetric (TG) curves were used. Kinetic parameters (the apparent activation energy E and preexponential factor Z) were calculated after isoconversional method for the first stage of dynamic degradation where dehydrochlorination (DHCl) of PVC and/or CPE is the main degradation reaction. Despite the chemical resemblance, the degradation mechanisms of CPE and PVC are different, as a consequence of differences in microregularity of the corresponding polymer chains. The addition of Ca/Zn carboxylates as well as the ratio of Ca and Zn carboxylates have considerably different influence on the investigated polymers.

Ca/Zn carboxylates; chlorinated polyethylene; poly(vinyl chloride); thermogravimetric analysis; thermooxidation

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