POLYMER DEGRADATION BY ELIMINATION .I. THERMAL DEGRADATION OF POLY(VINYL CHLORIDE) AND KINETIC TREATMENT OF PROCESS

The kinetics of the overall process of the thermal degradation of dissolved poly(vinyl chloride), taking place under oxygen-free conditions, have been studied. On the basis of the experimental data concerning dehydrochlorination and polyene formation, it has been supposed that the overall thermal degradation process consists of a special chain (zip-) reaction. The initiating step of this reaction is the random decomposition of the monomeric units. The chain propagation consists of series of allyl activated decomposition steps resulting in the formation of conjugated double bonds. The small kinetic chain length is, however, the consequence either of the existence of special polymer sequences along which degradation can proceed, or the possibility of a reaction step interrupting the propagation of activation. The kinetic treatment of the process has been accomplished, based on the assumption of special polymer sequences. Relationships have been obtained concerning the conversion of dehydrochlorination, as well as the concentration and length distribution of polyenes. The calculated results are in good agreement with the experimental data; the real physical and chemical significance of the probability factor appearing in these results has not yet been decided. © 1969.