Study on E-51/DDS system modified by silsesquioxane based on (3-glycidoxypropyl) trimethoxysilane

The E-51 epoxy resin modified by adding 3-glycidoxypropyl polyhedral silsesquioxane cage and using equivalent 4,4'-diaminodiphenyl sulfone (DDS) as the curing agent were studied. The FTIR spectrum, gelation characteristics and differential scanning calorimetry (DSC) were used to study the curing behavior and kinetics of the composites. The mechanical properties of the systems were also considered. The results showed that the cured reaction had lower activation energy E_a=48.7 kJ/mol. The heat deformation temperature (HDT), thermal decomposition temperature and glass transition temperature (T_g) of the composite were 200°C, 442°C and 245°C, and were 31°C, 58°C and 20°C respectively higher than that of E-51/DDS system under the same curing condition. This composite had higher thermal residue, which can be as high as 25% at 800°C. The flexural and impact strength were basically unchanged at the same time.