Effects of constituent materials on resin separation from CFRP by electrical treatment

Abstract

Carbon fiber-reinforced plastics (CFRP) waste is typically recycled through feedstock recycling, which recovers carbon fibers from CFRP by employing an aggressive thermal process to break down the resin matrix. However, this process faces challenges, as oxygen gas during heating has difficulty penetrating dense composites, resulting in low-quality recovered carbon fibers (rCFs). It was demonstrated that high-grade rCFs could be obtained by combining the thermal process with a short period of electrical treatment (ET). In this study, we investigated the effects of fiber orientation and matrix type on the separation efficiency (SE) by ET using uni-directional (UD-) and plain-weave (PW-) CFRPs, as well as twill-weave CFRTP. The results indicated that the SE value of UD-CFRP was nearly equal to that of PW-CFRP, suggesting that fiber orientation did not significantly affect resin removal. In contrast, the SE value of CFRTP was four times higher than that of CFRPs at a low constant voltage, as the separation resistance of the matrix decreased owing to thermal-oxidative degradation caused by moderate temperatures resulting from Joule heat and oxygen generated on the anode side.