Mild chemical recycling of aerospace fiber/epoxy composite wastes and utilization of the decomposed resin

Carbon fiber reinforced polymers (CFRPs) with high Tg (>200 °C) are indispensable for aerospace industry where high service temperature is required. Chemical recycling of the matrix polymers for these CFRP composites is more difficult than that of their low Tg analogues. In this work, an efficient approach for mild chemical recycling of CFRP with a Tg of ∼210 °C was developed using a ZnCl2/ethanol catalyst system. The high efficiency of ZnCl2/ethanol was attributed to the strong coordination effect of ZnCl2 with the C-N bonds and the strong swelling ability of ethanol, which worked together to break down the chemical bonds of the cross-linked polymer. Also, mild degradation temperature (<200 °C) imparted little damage to the recovered fibers. The decomposed matrix polymer (DMP) was in the oligomer form and contained multifunctional reactive groups. When DMP was used as a reactive ingredient and added up to 15 wt% to the preparation of new epoxy materials, the resulting cross-linked polymers could still retain the high strength and modulus compared to the neat polymer without addition of DMP.