Investigations of solution-mixed PVDF/PMMA polyblends by thermal, structural, and dielectric techniques

Abstract

PVDF/PMMA polyblends have been investigated over the entire composition range by DSC, IR. XRD, SEM, and dielectric techniques. Crystallization of PVDF is observed in the polyblends with PVDF content ≥20 wt%. DSC results indicate depression of crystalline melting temperature of PVDF crystals in the polyblend samples. Glass transition temperature of the amorphous phase is also lowered with the increase in the PVDF concentration. XRD and IR absorption results show the predominance of phase III crystals in pure PVDF as well as polyblend samples. SEM micrographs show spherulitic crystal structure of PVDF; the size of the spherulites is about 18 μ. These spherulites become gradually less distinct as the concentration of PMMA increases in the polyblend samples. A small hump is observed in the dielectric loss thermograms of the polyblends which could be due to the β-relaxation of PMMA and the glass transition of the amorphous phase of the polyblends. The α_c-relaxation, which has generally been observed for phase II PVDF, does not appear in the dielectric loss thermograms of PVDF and of polyblend samples, indicating the absence of phase II PVDF in our samples.