DEGRADATION AND STABILIZATION OF POLY(VINYL CHLORIDE) .2. SIMULATION OF THE POLY(VINYL CHLORIDE) DEGRADATION PROCESSES INITIATED IN THE POLYMER BACKBONE
R. Bacaloglu et M. Fisch, DEGRADATION AND STABILIZATION OF POLY(VINYL CHLORIDE) .2. SIMULATION OF THE POLY(VINYL CHLORIDE) DEGRADATION PROCESSES INITIATED IN THE POLYMER BACKBONE, Polymer degradation and stability, 45(3), 1994, pp. 315-324
The thermal degradation of PVC consists of a slow initiation followed
by a chain of fast reactions generating a series of active intermediat
es with an increasing number of double bonds. Each of these intermedia
tes partitions between a relatively stable polyene (termination reacti
on) and the next intermediate of the chain (propagation reaction) (Sch
eme 1). Experimental time dependencies of hydrochloric acid evolution,
rates of polyene sequence and benzene formation in solid PVC degradat
ion, data from the previous paper of this series, were simulated using
a simplified model (Scheme 2). Mean rate constants and activation par
ameters for random initiation, propagation and termination reactions o
f the PVC degradation chain were calculated. All three types of reacti
ons have low activation enthalpies and entropies suggesting concerted
hydrogen chloride eliminations.