In this study, poly(vinyl chloride) (PVC) and silica (SiO 2 ) microcomposites and nanocomposites were prepared by melt mixing in a Haake torque rheometer. The fusion and rheological behaviors of PVC/SiO 2 composites were evaluated by means of torque data recorded during processing to investigate the influence of the SiO 2 particle size on these behaviors. It was found that the fusion time and the fusion temperature decreased with the decreasing of SiO 2 particle size, whereas the fusion torque increased with the decreasing of particle size. The PVC/Si-25-nm nanocomposite (PVC including the 25 nm of SiO 2 ) showed the highest apparent viscosity among the PVC/SiO 2 microcomposites and nanocomposites prepared in this study. Scanning electron microscopy results demonstrated that some aggregates, whose sizes about 60-90 nm, were formed when the 25 nm of SiO 2 was used as filler. POLYM. ENG. SCI., 51:1574-

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In this study, imidazolium functionalized poly(vinyl alcohol) (PVA) was synthesized by acetalization and direct quaternization reaction. Afterwards, composite anion exchange membranes based on imidazolium-and quaternary ammonium-functionalized PVA were used for direct methanol alkaline fuel cell applications. 1 H NMR and Fourier transform infrared spectroscopy data indicated that imidazole functionalized PVA was successfully synthesized. Inductively coupled plasma mass spectrometry data demonstrated that the imidazolium structure was efficiently obtained by direct quaternization of the imidazole group. Composite anion exchange membranes were fabricated by application of the functionalized PVA solution on the surface of porous polycarbonate (PC) membranes. Fuel cell related properties of all prepared membranes were investigated systematically. The imidazolium functionalized composite membrane (PVA-Im/PC) exhibited higher ionic conductivity (7.8 mS cm −1 at 30°C) despite a lower water uptake and ion exchange capacity value compared to that of quaternary ammonium. In addition, PVA-Im/PC showed the lowest methanol permeation rate and the highest membrane selectivity as well as high alkaline and oxidative stability. Dynamic mechanical analysis results reveal that both composite membranes were mechanically resistant up to 10 7 Pa at 140°C. The superior performance of imidazolium functionalized PVA composite membrane compared to quaternary ammonium functionalized membrane makes it a promising candidate for direct methanol alkaline fuel cell applications.

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