The effect of processing history of poly(methyl methacrylate)-poly(vinyl acetate) mixture on the miscibility of components and the structure of the system

The concentration dependence of the Gibbs free energy of mixing PMMA with PVA was calculated for the entire concentration range on the basis of the data of static sorption of chloroform vapor by the films of PMMA, PVA, and their mixtures. The results obtained show that the system is a metastable one, and, depending on the processing history, behaves as either a homophase or a two-phase system. Phase separation upon heating is characterized by a binodal with a lower critical solution temperature ; the structural transition in a single-phase system occurs in the range of concentrations, where the concentration dependence of the Gibbs energy of mixing is convex, witnessing reduced interaction between the components.