Three series of epoxy/SiO 2 composites, containing 0.3-7 wt % nanosized SiO 2 with different specific surface area, were prepared by solution blending. The resulting composites exhibit the higher glass transition temperature (T g ) than that of pure epoxy. The T g of composite showed a maximum increment of 35.3C by the addition of 7 wt % A300. The trade name of A300 is Aerosil 300. It is one of the fumed silica nanoparticles products of Degussa. The decomposition temperatures (T d ) of composites were always higher than that of pure epoxy and showed a maximum increment of 20.8C by the addition of 5 wt % A300. The light transmittance of composites was as a function of the SiO 2 content and size. The water permeability of composites decreased with increasing SiO 2 content and the 7 wt % A300 composite exhibits a maximum decrement percentage of 35.6%. The T g , T d , storage modulus, and water-vapor barrier property are as a function of the SiO 2 content and size. These properties increased as the content of SiO 2 increased. The finer SiO 2 are more effective in increasing the T g , T d , and water-vapor barrier property.
A series of epoxy/SiO2 composites, containing 0.5, 1, 3, 5, and 7 wt.% SiO2 nanoparticles, were prepared by solution blending. Differential scanning calorimetry (DSC) indicated that the glass transition temperatures (Tg) of the composites were higher than that of the pure epoxy and rose as the SiO2 content increased. The decomposition temperatures (Td) of the composites were always higher than that of the pure epoxy, the maximum increase of 20.8 °C being achieved with the addition of 5 wt.% SiO2. The light transmittance of the composites was still higher than 80% with up to 7 wt.% SiO2. The water permeability of the composites decreased with increasing SiO2 content, and the 7 wt.% SiO2 produced a composite with the maximum permeability decrease of 56.3%. Scanning electron microscopy (SEM) showed that finer silica was dispersed in the epoxy matrix without large agglomerates.
A series of epoxy methacrylate/silica hybrids, containing 0.5, 1, 3, 5, 7, 10, and 15 wt.% tetraethyloxysilane (TEOS), were synthesized by sol-gel process. Differential scanning calorimetry (DSC) indicated that the glass transition temperatures (Tg) of the hybrids were higher than that of the pure epoxy methacrylate, the maximum increase of 26.7 °C being achieved with the addition of 3 wt.% TEOS. The decomposition temperatures (Td) of the hybrids were higher than that of the pure epoxy methacrylate (EMA) and rose as the TEOS content increased. The light transmittance of the hybrids was still higher than 80% with up to 15 wt.% TEOS. The water permeability of the hybrids decreased with increasing TEOS content to 7 wt.%, and then increased to 15 wt.%. The hybrid with 7 wt.% TEOS exhibited a maximum permeability decrease of 54.0%. Scanning electron microscopy (SEM) showed that the number of dispersed droplet of silica increased as the content of TEOS increased.
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