Influence of fiber/matrix interface on gas permeability properties of CF/TP composites

Abstract

For hydrogen application, one of the most important material property required is low gas permeability. In composite materials, this property depends on the materials but also on the processing parameters. In particular the residual porosity, but also the quality of the fiber/matrix interface, play a crucial role. This is particularly the case in composites involving a thermoplastic matrix with carbon fibers as the lack of reactive groups on the fiber surface can limit the level of interfacial interactions between the reinforcement and the matrix. In this study, the role of the interface is analyzed through the investigation of the hydrogen permeability of carbon fiber reinforced thermoplastics (CF/PVDF and CF/PPS) using different polymers and carbon fibers. The hydrogen permeability of the composites was measured, and a correlation with the crystallization behavior of the matrix on the fiber surface was identified. Hydrogen permeability decreases when the fiber favors matrix nucleation. Nucleation is improved by increasing the surface roughness of the carbon fiber.