Carbon fiber surfaces and composite interphases

Carbon fiber reinforcements with an excellent mechanical performance to weight ratio are primarily preferred for advanced composite applications. The poor interfacial adhesion between carbon fiber surfaces and polymer molecules caused intrinsically by hydrophobicity and chemical inertness of carbon is a long existing issue to overcome. The article intends to review the research work carried out over the past couple of years in the area of carbon fiber surface modifications and carbon fiber/polymer interfacial adhesion. This paper provides a systematic and up-to-date account of various ‘wet’, ‘dry’ and ‘multi-scale’ fiber surface modification techniques, i.e., sizing, plasma, chemical treatments and carbon nano-tubes/nano-particles coating, for increasing the wettability and interfacial adhesion with polymeric matrices. The review highlights strategies for retaining the carbon fiber mechanical strength after surface modification and stresses its significance.