Elucidation of damage factors to recycled carbon fibers recovered from CFRPs by pyrolysis for finding optimal recovery conditions

The purpose of this study is to further the search for the optimal conditions for the recovery of recycled carbon fiber (rCF) from epoxy matrix CFRP by thermal decomposition. We revealed that an oxidizing atmosphere was required to recover rCF. By investigating the strength reduction of CF after the heat treatment (hCF), it was demonstrated that significant strength reduction occurred at 600 degrees C. The damage also depended on the treatment temperature and time because of the oxidative decomposition of the fiber surface. By comparing the virgin CF, hCF and rCF, it was demonstrated that the strength reduction of the rCF was caused not only by the thermal oxidative decomposition but also by its interaction with the resin. Additionally, the time required to recover rCF differs depending on the treatment temperature and the degree to which each effect on the CF in CFRP depended on the location of the CF. At low temperatures, recovery time was longer, and the differences in strength between rCF recovered from the inner and outer layers were large. although CF recovery was quick at high temperatures, but the strength was significantly lower because of the effect of the interaction with the resin.