MISCIBILITY AND PHASE-SEPARATION BEHAVIOR IN TERNARY BLENDS OF POLY(VINYLIDENE FLUORIDE-HEXAFLUOROACETONE) POLY(METHYL METHACRYLATE) POLY(VINYL ACETATE)

Miscibility of both binary and ternary blends between poly(vinylidene fluoride-hexafluoroacetone) P(VDF-HFA), Poly(methyl methacrylate) (PMMA) and poly(vinyl acetate) (PVAc) was investigated by using dynamic mechanical and differential scanning calorimetric measurements. The interaction parameter in binary blends of P(VDF-HFA) and PMMA was -0.73 at 125-degrees-C and was largely affected by the existence of hexafluoroacetone units, compared with that of blends of poly(vinylidene fluoride) and PMMA. Phase separation behavior of this binary blends was elucidated by observing the change of transmittance on heating; the lower critical solution temperature (LCST) behavior was shown including both binodal and spinodal curves. Binary blends of P(VDF-HFA)/PVAc were also miscible and showed LCST behavior. Ternary blends of P(VDF-HFA)/PMMA/PVAc were miscible in spite of immiscible binary blends of PMMA/PVAc and showed LCST phase diagram. After phase separation, ternary miscible blends were separated to two phases of P(VDF-HFA)/PMMA with very small domains of PVAc and P(VDF-HFA)/PVAc with also very small PMMA. At higher temperature, phase separation composed of P(VDF-HFA)/PMMA and P(VDF-HFA)/PVAc occurred.