Penetration Behavior Analysis of Resin During the Impregnation Progress of Expanded Graphite Plates

Abstract

AbstractResin impregnation is an important process in the manufacture of composite graphite bipolar plates to reduce their porosity and improve their air tightness as well as flexural strength. In order to improve the filling efficiency of resin into expanded graphite plates and to investigate the factors influencing the resin penetration process, we compare the penetration rate and the upper limit of absorption of epoxy resin, acrylic resin and water in graphite plates. It was found that capillary force is part of the driving forces for resin penetration into the graphite plates, while the boundary layer is the main source of resistance. The higher viscosity of the resin not only leads to a lower resin flow rate, but also results in the formation of a thicker boundary layer, creating additional resistance. Further, the pores are not permeable by resin when the thickness of the boundary layer is greater than the pore size, which is an important reason why the expanded graphite plate is difficult to be filled by resin adequately.