Improvement on Heat-durability of Phenoxy Resin by Bismaleimide Doping

Abstract

Phenoxy resin is an engineering plastic, which is widely used as an insulating mold material, for example self welding insulating sheets that have superior moldability and low-material costs. To improve heat-durability of the phenoxy resin, the material was doped with bismaleimide, which is a thermosetting material. We investigated the behavior of bismaleimide doped phenoxy resin in a heat treatment process by using a differential scanning calorimeter (DSC). We also investigated heat durability as a thermal index (T_i) of heat treated phenoxy resin with bismaleimide by using thermogravimetric analysis with the Ozawa－Flynn－Wall method. From a heat-flow profile in the DSC, the exothermic peak temperature of the bismaleimide doped phenoxy resin was lower than that of the bismaleimide. The glass transition temperature (T_g) of the heat treated phenoxy resin with bismaleimide was higher than the T_g of the non heat treated bismaleimide-doped phenoxy resin. In IR measurement, the number of hydroxyl groups of phenoxy resin with bismaleimide decreased after heat treatment. These results suggest that bismaleimide reacts with phenoxy resin. The T_i of the heat treated phenoxy resin with bismaleimide depends on the doping ratio of bismaleimide. Heat-durability of phenoxy resin increases by doping the resin with thermosetting materials, such as bismaleimide, and by subjecting the resin to heat treatment.