Effects of Processing Conditions and Crystallization on Dynamic Relaxations in Semicrystalline Poly(vinylidene fluoride) Films

The dielectric relaxation of semicrystalline poly(vinylidene fluoride) films containing different crystalline phase structures was investigated using broadband dielectric spectroscopy. The molecular origins of the dielectric relaxation were assigned based on dynamic mechanical analysis and their correlation with findings obtained from Fourier transform infrared spectroscopy, wide-angle X-ray diffraction, small-angle X-ray scattering, and differential scanning calorimetry. Three dielectric relaxation processes were observed for all samples and they were attributed to the local motion of amorphous chains (beta), the segmental relaxation of amorphous chains (alpha(1)), and the process arising from Maxwell-Wagner-Sillars interfacial polarization (alpha(MWS)). In addition, poly(vinylidene fluoride) composing the alpha crystalline phase exhibited a strong relaxation of the local conformational rearrangement of the alpha crystalline phases (alpha(2)). The correlation between crystal structure and the dielectric relaxations indicates that semicrystalline poly(vinylidene fluoride) prepared from different processes contained the alpha crystalline phase as defects except for from the melt process.