Fatigue crack propagation behavior of interpenetrating vinylester/epoxy resins

摘要

Thermosetting resins of interpenetrating network structure (IPN) are gaining in importance owing to their outstanding toughness characteristics. The combination of styrene crosslinkable vinylester (VE) and amine crosslinkable epoxy (EP) resins is very promising as their mechanical and rheological properties can be tailored in a broad range [1-4]. It was recently argued that VE with an aromatic backbone (bisGMA type) should be combined with EPs of aliphatic or cycloaliphatic build-up in order to achieve optimum toughness [4,5]. The presence of IPN in the related VE/EP hybrids was demonstrated using "physically etched" specimens produced by ion bombardment [6]. Note that various ablation procedures (including laser treatment [7,8]) proved to be suitable tools to study the morphology of thermosetting resins. Interestingly, only few works were dedicated to the fatigue crack propagation (FCP) of interpenetrated thermosets [9,10] although this behavior is of paramount importance for many engineering applications. Therefore the present investigation was focused to study the FCP behavior of VE/EP combinations as a function of VE/EP ratio, EP formulation and curing conditions.