Interphases in composites

Abstract

During the cure of thermosetting polymer-matrix composites, the presence of reinforcing fibers significantly alters the resin composition in the vicinity of the fiber surface via several microscale processes, forming an interphase region with different chemical and physical properties from the bulk resin. The interphase composition is an important parameter that determines the composite micromechanical properties and the durability of the products in service. Historically, the description of the interphase has been rather empirical and because of the complexities of the molecular level mechanisms near the fiber surface, few studies have been carried out on the prediction of the interphase evolution as function of the process parameters. This chapter provides an overview of the existing thermodynamic and kinetics-based models for describing the interphase in composites and related experimental studies. The models are used to develop the processing-interphase and interphase-property linkages, which form the basis for guiding the process design for tailored composite properties and performance.