Phase Transitions and Thermodynamic Interaction Parameters of Components in Poly(methyl methacrylate) and Poly(vinyl acetate)

Phase diagrams with UCST are constructed for systems poly(methyl methacrylate)–butanol, poly(vinyl acetate)–methanol, and poly(vinyl acetate)–2-propanol. The boundary curve of the PMMA– о -xylene system is unusual in shape, which is explained by the fact that polymer macromolecules form stereo complexes that appear during solution cooling. The thermodynamic interaction parameters χ of components and the values of χ cr and critical concentration of the systems under study are calculated. With increasing temperature the value of χ decreases, which indicates that the interaction of components is improved under heating and agrees with the phase diagrams of the systems.