INTERNAL-STRESS OF EPOXY-RESIN MODIFIED WITH ACRYLIC POLYMERS CONTAINING FUNCTIONAL-GROUPS PRODUCED BY INSITU UV-RADIATION POLYMERIZATION

To reduce the internal stress generated in cured epoxy resin by shrinkage in the cooling process from cure temperature to room temperature, three kinds of acrylic polymer were introduced by in situ ultraviolet radiation polymerization before the curing. They were polybutyl acrylate (A), butyl acrylate-glycidyl methacrylate copolymer ( 95 5, mole ratio) (B) and butyl acrylate-monoethylene glycol dimethacrylate copolymer ( 95 5, mole ratio) (C). In the A and B modified resins, a heterogeneous structure with spherical shaped submicrometre domains consisting of acrylic polymers was formed. In the C modified resin, a heterogeneous structure with irregularly shaped submicrometre domains was formed. Further, in the B and C modified resins, microphase separation was observed in the domains. These results suggest that the interaction between acrylic polymer domains and the epoxy matrix increased in the order C>B>A modified resin. As a result of the modifications, the modulus and the internal stress of cured epoxy resin decreased effectively in the same order. © 1990.