Effect of rheological transitions in matrix resin on flow mechanism of carbon Fiber/Epoxy prepreg

Abstract

There are two types of flow mechanism in prepreg processing: shear flow, in which resin and fibers flow together, and percolation flow, in which resin flows out of the gaps between fibers. In this study, we experimentally evaluated how these flow mechanisms change during cure including the gelation stage. Results of compression tests at various initial degree of cure at the start of compression showed that the maximum amount of shear flow is almost constant before matrix gelation. In the gelation region of matrix resin, shear flow still occurs at the gel point whilst percolation flow has completely stopped. Furthermore, it was suggested that the limit of the shear flow in the gelation stage can be described by the combined effects of the shear modulus of the fiber-bed and the shear storage modulus of matrix resin.