Abstract
In general the mechanical properties of FRTPs (fiber reinforced thermoplastics) are inferior to those of FRPs (fiber reinforced plastics). This caused by the length of reinforcing fiber in FRTPs is shorter in FRPs, and relatively low content is available because TP (thermoplastic) resin has much higher melt viscosity than TS (thermosetting) resins which is used in FRP. The main objective of this study is to present an FRTP that has excellent mechanical properties with continuous reinforcing fiber in high volume. For one trial, we investigated an FRTP using an in situ polymerizable polyamide 6 as the matrix for the infusion molding process. This polyamide 6 is converted from its monomer into a TP polymer, by the ring-opening-polymerization of ε-caprolactam during the molding process at 160°C. The obtained FRTP had no voids and unfilled parts because ε-caprolactam has a very low viscosity at 100°C before polymerization. Bending tests revealed that the FRTP exhibited a high bending strength and modulus, compared to a conventional FRTP molded by hot press molding with polyamide 6 films and reinforcing cloths. Furthermore, the results of the bending tests indicate that surface treatment of the carbon fiber is effective at improving mechanical properties of the FRTP.
