MISCIBILITY OF PVDF PMMA BLENDS EXAMINED BY CRYSTALLIZATION DYNAMICS/

The crystallization dynamics of blends of poly(vinylidene fluoride) (P VDF) with atactic-, syndiotactic- and isotactic-poly(methyl methacryla te)s (PMMA) were analysed by differential scanning calorimetry under i sothermal conditions. Crystal growth rate (G) decreased with increasin g weight fraction of PMMA (phi PMMA) for PVDF/at-PMMA and PVDF/syn-PMM A blends. However, G of PVDF/iso-PMMA blends depended only on the degr ee of supercooling (Delta T) and was independent of phi(PMMA). Surface free energy (sigma) of PVDF crystals evaluated from G and nucleation rate depended on phi(PMMA) for PVDF/at-PMMA and PVDF/syn-PMMA blends, although sigma of PVDF/iso-PMMA was almost constant and independent of phi(PMMA). These results suggest that PVDF/at-PMMA and PVDF/syn-PMMA blends are miscible but PVDF/iso-PMMA blends are immiscible, a finding which was confirmed by the phase diagrams as determined from cloud po int measurements.