Evaluation of new GFRTP and CFRTP using epsilon caprolactam as matrix fabricated with VaRTM

• Main Authors: Ben Goichi, Hirabayashi Akiko, Sakata Kazuhiro, Nakamura Koichi, Hirayama Norio
• Format: Article
• Language: English
• Published: De Gruyter 2015-11-01
• Series: Science and Engineering of Composite Materials
• Subjects: carbon fabric; ε-caprolactam; frtp; gf textile; mechanical properties; vartm
• Online Access: https://doi.org/10.1515/secm-2014-0013
• ISSN: 0792-1233; 2191-0359

Thermoplastic resins used as a matrix of fiber reinforced thermoplastics (FRTPs) are composed of high polymers that remain highly viscous even at a higher temperature than their melting points. As a result, they need an even higher temperature, a higher pressure and a longer processing time to allow them to bond with fibers that require large and specialized equipment. In contrast, fiber-reinforced thermoset plastics (FRPs) can be easily molded owing to the use of lower viscosity liquid resin as the matrix using simpler devices. In this paper, a new fabrication method of FRTPs using in situ polymerizable ε caprolactam as the matrix is presented. This method uses vacuum-assisted resin transfer molding without the need for large and specialized equipment. The ε-caprolactam molecules were converted from their monomer form into a polyamide 6 resin, with ring-opening polymerization of ε-caprolactam during the molding process at a lower temperature than its melting temperature. The two kinds of FRTPs obtained using ε-caprolactam as the matrix had neither voids nor unfilled parts because ε-caprolactam had a very low viscosity before the polymerization. These FRTPs not only exhibit superior bending properties but also are suitable for high-speed molding, namely, within a few minutes of process time.