New approaches to the study of labile structures in poly(vinyl chloride) by phenolysis

Three samples of PVC having different tacticities were treated with phenol in cyclohexanone at 60° until there was no more reaction (96 hr). The incorporation of phenate into the chain was observed by u.v.-visible spectroscopy. The phenolysis extent was shown to be lower as the syndiotactic content of the polymer increased. On the other hand, the modified polymers showed enhanced thermal stability relative to the starting materials particularly for the more isotactic sample. The observed behaviour of either the starting materials in phenolysis or the treated polymers in thermal degradation appears to be very similar to that observed previously in the reaction with sodium thiophenate. On the basis of this similarity, it might be concluded that the phenolysis occurs with chlorine atoms at isotactic placements. That effect would confirm the thermal lability of some normal chlorine atoms as indicated by other results.