Effect of TiO_2 on Morphology and Mechanical Properties of PVDF/ PMMA Blend Films Prepared by Melt Casting Process

摘要

Effect of titanium dioxide (TiO_2) on morphology and mechanical properties of poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) blend films prepared at different TiO_2 contents by a melt casting process was studied. The results showed that tensile moduli in both the machine direction (MD) and the transverse direction (TD) increased with increasing TiO_2 content, and calculated tensile moduli based on the Halpin–Tsai and the Kerner model were consistent with experimental ones in both the MD and TD of films containing 10 wt TiO_2. However, experimental tensile moduli exhibited smaller values compared with calculated ones, as the TiO_2 content increased to 30 wt , and it was assumed that this is due to the decrease of crystallinity of PVDF. Morphological observations indicated that TiO_2 particles did not affect crystal structures of PVDF and the morphology of PVDF/PMMA amorphous phase, but hindered the crystallization of PVDF. The MD and TD elongation at break exhibited >200 and <20, respectively. The SEM micrographs revealed that spherulites could deform along the MD when the tensile force was applied along the direction. By contrast, spherulites could not deform along the TD and fractured at very small elongation, owing to the anisotropic morphology of spherulites.