Effect of TiO₂ on PVDF/PMMA composite films prepared by thermal casting

Melt-extruded poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA) blend films were prepared at different rutile (titanium dioxide, TiO ₂) concentrations for use as a protective sheet on a photovoltaic cell and module. The rheology, structure, morphology, crystalline behavior, thermal, and mechanical properties of PVDF/PMMA/TiO₂ composite films were investigated through reflectance difference spectrometer (RDS), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimeter (DSC), thermogravimetric analysis (TGA), scanning electron microscope (SEM), and color spectrometry. The results showed that the blended material and its film have favorable thermal and mechanical properties. The TiO₂ is finely dispersed in the composite, as shown by the crystalline regions of the PVDF and the homogeneous amorphous regions consisting of PVDF and PMMA, resulting in advantageous and optical properties of PVDF/PMMA/TiO₂ composite films. However, the TiO₂ can also greatly narrow the thermally stable region of the PVDF in PVDF/PMMA/TiO ₂ composite film because of the catalytic decomposition effect. The tensile strength and elongation at break are higher than those of a PVDF/PMMA blend as TiO₂ content increases. Increases in the crystalline behavior and rheological properties appeared below 20 wt% TiO₂ content. [Figure not available: see fulltext.]