Development of CFRTP Intermediate Substrates Using in-Situ Polymerizable Thermoplastic Epoxy Resin

This study aims to create a novel method for fast mass-production of carbon fiber-reinforced thermoplastic (CFRTP) intermediate substrates by using in-Situ polymerizable thermoplastic epoxy resin, which is fed on reinforcing fibers in monomer mixture form in impregnation process and then allowed to rapidly polymerize into linearly-extended thermoplastic high polymer. Comparison between the monomer viscosity of this resin and the melt viscosity of polypropylene (PP) implied that thermoplastic epoxy resin can impregnate into fiber bundles approximately 103 times faster than PP. The investigation of resin applying method to carbon fiber fabrics revealed that linearly applying method was better than planarly applying method in terms of less voids. Finally, two types of polymerization catalysts were investigated to rapidly polymerize thermoplastic epoxy resin. As a result, as short as 2.5-minute polymerization using the phosphorous-type catalyst allowed the resin polymerize into high polymer enough to exhibit practical flexural strength of 900 MPa or more when used as the matrix of CFRTP in the volume fraction of about 50 %.