Toughening of Thermosetting Resins Based on Improved Compatibility Induced by In Situ Generation of Modifier Polymers

Abstract

In this review, I will introduce recent researches on “in situ polymerization method” in which cured thermosetting resins are toughened by polymerizing modifier monomers dissolved in the resins in parallel with curing reaction of the thermosetting resins. The addition of the modifiers in the monomer state instead of the corresponding polymers reduces viscosity of the resins before curing to improve processability of the resin compositions. Compatibility between the uncured resins and modifier monomers is higher than that between the resins and polymers, and this higher compatibility is expected to fix the phase separations between the cured resins and in situ generated modifier polymers with finer structures, which leads to improved toughness of the cured resins. Various thermosetting resins including phenol-, anhydride- and amine-cured epoxy resins, cationically polymerized alicyclic epoxy resin, cyanate ester and benzoxazine resins are found to be effectively toughened by in situ generated modifier polymers such as poly(N-phenylmaleimide-co-styrene) with high glass transition temperature.