Structure development of PVDF/PMMA/TiO2 composite film with casting conditions

This study examined the effect of the casting temperature on poly(vinylidene fluoride) (PVDF)/poly(methyl methacrylate) (PMMA)/titanium dioxide (TiO2) composite films for use as the protective sheet of photovoltaic cells and modules. The structure, crystalline behavior, thermal behavior, surface morphology and color properties of the PVDF/PMMA/TiO2 composite films were investigated by FTIR, XRD, DSC, surface roughness analysis and color spectrometry. The results showed that different crystal structures-PVDF (form I) and PVDF (form II) - could be created in PVDF/PMMA/TiO2 composite films. By melt extruding PVDF/PMMA/TiO2 (65/20/ 15) blends, and casting at different temperatures, it was found that PVDF (form I) was predominant at low casting temperatures. However, with increasing casting temperature, PVDF (form II) dominated the PVDF/PMMA/TiO2 composite films. After aging and PCT (pressure cooker tester), form I came to dominate the PVDF/PMMA/TiO2 composite film and increased the Color - b index of CIELAB color space.