A comprehensive review of surface modification techniques for carbon fibers for enhanced performance of resulting composites

Carbon fiber (CF) is being used as reinforcements in structural composites due to its high strength-to-weight ratio, chemical and abrasion resistance. However, due to the inert surface of the fiber, the resulting CFRPs provide limited damage resistance. The CFRPs are prone to delamination and offer poor interfacial strength. Secondly, recycled carbon fiber (RCF) cannot be used for strength applications in electric vehicles and aerospace applications due to the limited strength offered by the CFRPs made from RCFs. So, in order to use recycled and virgin CF in the field of electric vehicles and aerospace, the modification to the surface of the CF is required for enhanced interfacial properties in the resulting composite. This is a comprehensive review on surface modification techniques used to induce physical and chemical changes on the CF surface. The modified surface of CF can lead to enhanced performance of the structural composites. The review article discusses the various surface modification techniques categorized as plasma, chemical, nano-particle growth, coating, and microwave irradiation in detail, with suitable illustrations that have been used to ameliorate the compatibility of the CF with the matrix.