Recycling of Polymer Matrix Composites

Carbon fibers recovered from a epoxy-based polymer matrix composite.

Carbon fiber reinforced polymer matrix composites (PMCs) are materials with superior strength-to-weight ratios. Finding increased applications in the aerospace industry, PMCs are now being evaluated for possible use in automobile construction. The material’s high cost, however, along with concerns about whether the PMCs will be recyclable when the vehicles reach the end of their useful lives, are barriers to its widespread use. With funding provided by the U.S. Department of Energy’s Vehicle Technologies Program (formerly called the Office of Advanced Transportation Technologies), Argonne is developing an efficient and cost-effective process to recover these valuable carbon fibers.

Argonne developed and tested a thermal treatment process to degrade the polymer substrate and recover the carbon fibers from the composites with minimal impact on the properties of the carbon fibers. Testing was conducted on scrap PMCs as well as on controlled samples in order to compare the properties of the fibers before and after treatment. Economic analysis of the process indicates that it has a potential payback period of less than two years. We also tested a chemical treatment method that will enable the recovery of thermoplastic substrates in addition to the carbon fibers.

Argonne has designed, built, and tested a continuous thermal reactor capable of treating 5 kilograms of PMC material per hour. Work performed has demonstrated that the recovery of carbon fibers from PMC scrap is technically feasible and potentially economical.

May 2008