UV-heat dually curable epoxy resin composites with low filler contents and high curing speed

Epoxy resin composites are a type of polymer-based materials with wide application scopes. A mass of fillers was added to improve thermal properties which may degrades mechanical properties at the same time. In addition, the common heat-curing process takes several hours to completely cure. To improve the performance of epoxy resin composites of low-content fillers, we prepare UV-heat dually curable epoxy resin with silicate ester. The overall curing time of UV-heat curing process is about half of the traditional thermal-curing process. The breakdown voltage of epoxy resin modified by silicate ester is up to 181 MV/m, which is increased by 50 % compared to pure epoxy resin. The silicate ester curing agent can react with both epoxy resin and silica fillers and can thus improve the dispersion of the fillers in the matrix and enhance the interaction between fillers and the resin. As a result, the coefficient of thermal expansion (CTE) of the composites was greatly reduced. The CTE of silicate ester-modified epoxy resin composites is 93 ppm/K and 137 ppm/K over the temperature range below and above its T_g, respectively, which is 25 % lower than those of normal epoxy resin composites.