Development of a photocurable glass-fiber reinforced epoxy-amine/thiol-ene composite

This work reports a rapid and efficient method to prepare photocurable glass-fiber reinforced epoxy composites. The curing agent for the developed epoxy photocurable systems is a tertiary tetramine functionalized with six allyl groups. The tertiary amine groups induce the anionic polymerization of the epoxy groups to produce the corresponding polyethers. At the same time the double bonds of the curing agent react with an added multifunctional thiol by means of the thiol-ene mechanism, forming polythioethers. These polythioethers affect the reactivity of the system because once formed they are basic enough to anionically polymerize the unreacted epoxy groups. Moreover, the flexibility of the polythioethers improves the toughness of the polyethers derived from the epoxy resin as demonstrated by the impact resistance determinations. When this epoxy-amine/thiol-ene system was tested to prepare glass fiber reinforced epoxy composites, completely cured specimens were obtained with modulus of approximately 25,000-29,000 MPa. The heat released during the thiol-ene photopolymerization contributes to completely cure the composite.