Investigation of an Abnormal [alpha] Polymorph Formation in Miscible PVDF Nanocomposite Blend Using Kinetics of Crystallization

Poly(vinylidene fluoride) (PVDF)/acrylic rubber (ACM)/Nanoclay miscible nanocomposite blends are prepared using melt-mixing method. Fourier transform infrared spectroscopy is employed to investigate the real-time conformational changes of PVDF chain segments during crystallization of corresponding nanocomposite blends under isothermal condition. This analysis demonstrates the formation of [alpha] polymorph in nanocomposite blends, which is quite abnormal compared to polymorphism of PVDF nanocomposite. Differential scanning calorimetry technique is also conducted to study the isothermal crystallization kinetic of the mentioned system. Furthermore, Avrami equation is employed to evaluate the overall crystallization rate. It is shown that addition of nanoclay to PVDF/ACM miscible blends slightly affects Avrami parameters. According to Lauritzen-Hoffman theory, the presence of crystals is observed at regime II of crystallization. Free energy of folding of miscible nanocomposite blends is comparable with that of miscible blends, suggesting the fact that PVDF molecules interact with ACM chains within nanocomposite blends, whereas nanoclay particles are wrapped by ACM molecules. De Gennes' theory is used to explain the emergence of a different polymorph in miscible nanocomposite blends compared to that in PVDF nanocomposites.