Kinetics of initial stage of the thermal dehydrochlorination of poly(vinyl chloride).

Abstract

Dehydrochlorination of poly(vinyl chloride) (PVC) under vacuum (about 10−4 mmHg), with continuous removal of volatile products by freezing out, has been studied at 200°C. A quantitative treatment of the scheme of consecutive reactions of PVC degradation in vacuo has been carried out. The contributions of each of the two processes of dehydrochlorination (that initiated by decomposition of unstable groups present in the original PVC and of normal links of macromolecules) into the overall rate of polymer degradation were estimated. Investigations were made on the effects of mild chlorination of PVC by chlorine in the dark and in sunlight at 20°C and of treatment of PVC at 80°C or 150°C by some compounds (tributyl phosphite, and its mixture with dibutyltin dichloride; bis(butyl maleate)-, bis(octyl maleate)-, bis(butyl thioglycolate) of dibutyltin; triethylsilicon, triethylgermanium, and mixtures of hydrides with dibutyltin dichloride) upon the rate of dehydrochlorination of the polymer in vacuo. It has been shown that the initial rate of degradation in vacuo decreases considerably only after treatment of PVC by mixtures of Si- or Ge-organic hydrides with dibutyltin dichloride. © 1978, The Society of Polymer Science, Japan. All rights reserved.