Morphological study of PVDF/PMMA/TiO_2 blend films prepared by melt casting process

摘要

The influence of chill roll temperature and thermal annealing on the morphology and dynamic mechanical behavior of poly(vinylidene fluoride) (PVDF)/ poly(methyl methacrylate) (PMMA)/titanium dioxide blend films prepared by a melt casting process was studied. The β phase of PVDF was formed at the chill roll temperature of 30℃. Furthermore, with the increase in this chill roll temperature, its structural conversion to the a phase was observed. No change in the crystal structure of either the (3 or a phase occurred on account of thermal annealing at 115℃ for 24 h. The decrement in the storage modulus above the glass transition temperature ascribed to the mixed amorphous phase became smaller, as the chill roll temperature increased. Based on morphological observations, we deduced that the reason for this decrement is not that the film cast at 115℃ was more crystalline than that cast at 30℃ but that the actual weight fraction of PMMA in the mixed amorphous phase of the film cast at 115℃ was lower than that of the one cast at 30℃.