Title: Chemical Recycling of Amine/Epoxy Composites at Atmospheric Pressure: Fiber Recovery and Matrix Reuse

Authors: Yijia Ma , Travis J. Williams, and Steven R. Nutt

DOI: 10.33599/nasampe/c.19.0762

Abstract: The increasing use of carbon fiber-reinforced polymers (CFRPs) poses environmental problems because most end-of-life CFRPs are sent to landfills due to a lack of practical recycling methods. In this study, we investigated the viability of recycling amine/epoxy composites using chemical treatment at atmospheric pressure. Two chemical approaches – depolymerization and acid digestion, both performed at atmospheric pressure – were first evaluated for neat amine-cured epoxies formulated with various crosslink density, and then for CFRPs fabricated from lab-made and commercial prepregs. Furthermore, decomposed matrices were recovered from the chemical feedstock and reused in new epoxy formulations. Results indicated that both approaches were effective for amine/epoxy composites, and the dissolution rate was affected by both the chemical reaction rate (acid digestion shows faster reaction rate than depolymerization) and the diffusion rate (diffusion rate can be improved by pre-treatment). To date, acid digestion with pre-treatment has provided the most effective route for extensively crosslinked amine/epoxy composites. Near-virgin quality fibers were recovered from composites produced using lab-made and commercial prepregs, as well as shredded composite waste. Moreover, we demonstrated that matrix polymers could be recovered and reused as accelerators for anhydride-cured bi-functional epoxies. Lastly, reaction mechanisms were identified and catalysts to accelerate the reaction rate were screened.

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Conference: CAMX 2019

Publication Date: 2019/09/23

SKU: TP19-0762

Pages: 15

Price: $30.00