Reactive blending of thermosets: Molecular, morphological and mechanical analysis

Abstract

A number of different approaches were used to enhance the toughness of tri- and tetrafunctional epoxies and of unsaturated polyester resins. In the case of epoxies, tough, thermally stable, engineering thermoplastics, namely a bisphenol-A polycarbonate and a thermoplastic poly(ether imide) (Ultem 1000) were employed as modifiers. For unsaturated polyesters a different approach was adopted: two commercial liquid rubbers were chemically modified to enhance their reactivity towards the matrix functionalities. In particular, a hydroxy-terminated polybutadiene and an aminoterminated butadiene-acrylonitrile copolymer were transformed into isocyanate-terminated and maleimide-terminated rubbers, respectively. A further system which is described in the present contribution is aimed at mitigating another deficiency of the polyester matrix, namely its rapidly decreasing rigidity at temperatures above room temperature. In this case, a thermosetting bismaleimide was incorporated into the resin as a co-reactive second component.