Composites formed by glass fibers and PS‐modified epoxy matrix. Influence of the glass fibers surface on the morphologies and mechanical properties of the interphases generated

Abstract In this work, the influence of the nature of the reinforcement surface on the interfacial morphologies developed in E‐glass fibers/polystyrene (PS)‐modified epoxy composites has been studied. Different surface modifications of the fibers were considered. In a complementary way, morphological analysis and nanoindentation measurements were carried out using atomic force microscopy to subsequently correlate the interfacial structure with the morphologies observed. In every composite, reaction‐induced phase separation happened with a morphology composed of PS‐rich domains immersed in an epoxy‐rich phase. However, depending on the surface modification of the glass fibers, different distributions of PS‐rich domains at the interfaces were obtained. The results were interpreted in terms of a gradual phase separation process because of stoichiometric gradients from the glass fibers surface to the matrix bulk caused by specific segregation of one of the components of the reactive epoxy mixture to the fibers occurs. It was concluded that specific and controlled reinforcement modification allows obtaining tailored interfaces formed by a polymer blend and a reinforcement in which the morphology can be previously selected. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers