Development of a coarse spherulite in poly(vinylidene fluoride) poly(methyl methacrylate) blends

The spherulite formation in poly(vinyliden fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) blend was investigated by time-resolved light scattering under I-I, (cross-polarized) optical alignment using (CCD) camera system. The final morphology was observed by atomic force microscopy (AFM) images and optical microscope (OM). The coarse spherulite was observed at high temperature (162 degrees C) by OM, whereas the compact spherulite was appeared at low temperature (148 degrees C). In the compact spherulite, the spherulite radius linearly increased with time. The order parameter defined by the sharpness of Hv scattering profile monotonously decreased with crystallization In the coarse spherulite, the spherulite linearly grew, stopped growth for a while, and then restarted i.e., a pause in growth was observed. It was ascribed to the rejection of the noncrystallizable component (PMMA) at spherulite growth front. The order parameter initially increased, attained a maximum, and then decreased. Time at maximum point was consistent with onset time of a pause in the spherulite growth. Thus, a maximum in order parameter may be ascribed to the rejected PMMA at the spherulite growth front. A supplemental evidence for these results was provided by the morphology observation of the AFM.