PHASE-BEHAVIOR AND GELATION OF SOLUTIONS OF POLY(VINYLCHLORIDE)

The phase behavior and the thermoreversible gelation of solutions of P VC in nitrobenzene has been studied. Two concentration domains have to be considered. At low polymer concentration isothermal annealing resu lts in a relatively high degree of crystallinity without the formation of a gel network. At higher polymer content, cooling results in the f ormation of a thermoreversible gel of low crystallinity. This crystall inity increases after isothermal annealing. The influence of polymer c ontent and annealing temperature is investigated. A model, based on th e formation of cooperative intermolecular association, is proposed in order to explain this complex phase behavior.