Functionalised plasma polymer coatings for promoting the adhesion of high-performance polymer fibres

摘要

A plasma copolymerised functional coating of acrylic acid and 1,7-octadiene was deposited onto high-strength and high-modulus poly(p-phenylene benzobisoxazole) (PBO) fibres in order to improve their adhesion to epoxy resin. The chemical structure of the plasma polymer on PBO was investigated using X-ray photoelectron spectroscopy (XPS) with trifluoroethanol derivatisation technique. This confirmed that the PBO fibre was covered completely with the plasma copolymer and that the deposit contained a quantitative concentration of carboxylic acid groups. The mi-crodebond test was used to evaluate the interfacial shear strength (IFSS) and the relationship between surface functionality and adhesion. The surface retention of carboxylic acid groups could be controlled by changing the ratio of monomers at constant plasma power. IFSS was observed to increase with the increase in the retention of carboxylic acid groups. The tensile strengths of single fibres with or without coating were comparable. These results show that the plasma polymerised coatings can control the interfacial bond between PBO fibres and the matrix resin without any damage to the mechanical properties of the fibres.