Manufacture of carbon nanotube-grafted carbon fiber reinforced thermoplastic composites

Carbon fiber reinforced composites (CFRCs) have been used in various high-end industries due to their outstanding specific mechanical properties. Recently, carbon nanotube (CNT)-grafted carbon fibers (CFs) made via direct growth has emerged as an advanced and hierarchical reinforcement that can improve the reinforcing effect of CFs in CFRCs. On the other hand, CF reinforced thermoplastic composites (CFRTPs) have attracted much attention because of their quick and mass production capability, e.g., which is important for automotive part manufacturing. Here, we report on the manufacture of CFRTPs using CNT-grafted CFs and their mechanical properties. First, the interfacial shear strength of CNT-grafted CFs with thermoplastic resins was characterized to demonstrate improved interfacial properties due to the CNTs grafted on CFs. Then, the composites were manufactured in two ways; polymer nanoparticles and in-situ polymerization. Polymer nanoparticles were used to improve the interfacial properties due to their small size and good mechanical locking with CF surfaces. In-situ polymerization was also used to manufacture CFRTPs, i.e., monomers with catalyst were transferred into CNT-grafted CF fabric preform using vacuum assisted resin transfer molding and then polymerized into solid matrix. This in-situ polymerization enabled the manufacture of CNT-grafted CF thermoplastic composites by overcoming the difficulties of filling the surface of CNT-grafted CFs with thermoplastic polymers. Finally, the mechanical, thermal, electrical, and damping properties of CNT-grafted CF thermoplastic composites were characterized and compared with their thermoset composites.