Epoxy-functionalized polyhedral oligomeric silsesquioxane/cyanate ester resin organic-inorganic hybrids with enhanced mechanical and thermal properties

A series of cyanate ester resin (CE) based organic-inorganic hybrids containing different contents (0, 5, 10, 15 and 20 wt%) of epoxy-functionalized polyhedral oligomeric silsesquioxane (POSS-Ep) were prepared by casting and curing. The hybrid resin systems were studied by the gel time test to evaluate the effect of POSS-Ep on the curing reactivity of CE. The impact and flexural strengths of the hybrids were investigated. The micromorphological, dynamic mechanical and thermal properties of the hybrids were studied by SEM, dynamic mechanical analysis (DMA) and TGA, respectively. Results showed that POSS-Ep prolonged the gel time of CE. CE10 containing 10 wt% POSS-Ep displayed not only the optimum impact strength but the optimum flexural strength. SEM results revealed that the improvement of mechanical properties was attributed to the large amount of tough whirls and fiber-like pull-outs observed on the fracture surfaces of CE10. DMA results indicated that POSS-CE tended to decrease E of the hybrids in the glassy state but to increase E of the hybrids in the rubbery state. TGA results showed that CE10 also possesses the best thermal stability. The initial temperature of decomposition (T-i) of CE10 is 426 degrees C, 44 degrees C higher than that of pristine CE. (c) 2013 Society of Chemical Industry