Effect of initial polymer concentration on the crystallization of poly (vinylidene fluoride)/poly (methyl methacrylate) blend from solution casting

The effect of initial polymer concentration on the crystallization of a poly (vinylidene fluoride) (PVDF)/poly (methyl methacrylate) (PMMA) blend (mass ratio=70/30) prepared by solution casting was investigated. Confirming by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC) and wide angle X-ray scattering (WAXD), exclusively phase was observed in the films regardless of initial polymer concentration. Surface film morphologies examined by scanning electron microscopy (SEM) were found to be strongly dependent on the concentration. An increase of concentration resulted in a decrease of the spherulite size and a uniform distribution of PVDF spherulites owing to the fast formation of nuclei at high concentration. Correspondingly, the lateral crystal size and crystallinity of PVDF obtained from high concentration c (10wt.%) was less than those generated from low concentration (5-10wt.%). This was mainly due to the reduced growth of PVDF crystals, which was caused by the increased solution viscosity and entanglement of the polymer chains with increase of concentration.