MISCIBILITY OF POLY(VINYLIDENE FLUORIDE) AND POTASSIUM-SALT OF POLY(METHYL METHACRYLATE-RAN-METHACRYLIC ACID)

The crystalline-amorphous polymer pair of poly(vinylidene fluoride) and poly(methyl methacrylate) is known to be miscible over a wide composition range. The effects of ionic moieties on the miscibility were studied by replacing the poly(methyl methacrylate) with a series of random copolymers of methyl methacrylate and potassium salt of methacrylic acid. The interaction parameter (chi) for the miscible blends in their molten state was obtained by thermal analysis using a melting-point depression calculation. The parameter decreased to a minimum at c. 2% ion content (chi = -0.514) and approached a positive value at above 10% ion concentration.