Mechanical characterization of copolymers based on benzoxazine and epoxy

A new class of phenolic-like thermosetting resins has been developed that is based on the ring opening polymerization of a benzoxazine precursor. These new materials overcome many of the traditional shortcomings associated with conventional novolac and resole-type phenolic resins, while demonstrating excellent physical and mechanical characteristics. The benzoxazines are copolymerized with an epoxy resin in order to modify their performance. The addition of epoxy to the polybenzoxazine network greatly increases the crosslink density of the thermosetting matrix and strongly influences its mechanical properties. Copolymerization leads to significant increases in the glass transition temperature, flexural stress, and flexural strain at break over those of the polybenzoxazine homopolymer, with only a minimal loss of stiffness. By understanding the structural changes induced by variations of epoxy content and their effect on material properties, the network can be tailored to specific performance requirements. Copyright (C) 1996 Elsevier Science Ltd.