Title Catalytic Process for the Reclamation of Carbon Fibers from Carbon/Epoxy Composites
Source Proc. Soc. Plastics Eng. Annual Recycling Conf., ARC 99
Year 1999
Author(s) Allred, R. E.; Busselle, L. D.; Shoemaker, J. M.
Abstract The depolymerization of thermoset carbon fiber-reinforced epoxy matrix composites was studied to determine the significant reaction parameters, mechanistic reaction model, and fiber quality produced by a catalytic reclamation process. This process was designed to recover valuable carbon fiber and an organic fraction from the depolymerization of carbon/epoxy composites. Design of experiments was used to determine a regression model including terms for temperature, time, and agitation to estimate the purity of the carbon fiber produced from the reaction. Depolymerization of the composites appeared to follow a progressive conversion model similar to a solid catalyst reaction during the majority of the reaction. Significant feedstock parameters that will affect the rate of reaction were the surface area available for reaction and the thickness of the composite. The carbon fibers reclaimed from the reaction reached 99.8% carbon values, i.e., 0.2% residual resin, which is sufficient to meet the market specifications for reuse in conductive molding compounds. The fiber tensile strength showed an 8.6% reduction in strength after reclamation indicating that the process had little damaging effect on the fiber. Potential applications for the recycled fibers include thermoplastic and thermoset molding compounds and nonwoven sheet reinforcements. An economic analysis of a recycling business based on the catalytic depolymerization process showed that it should be profitable provided that adequate scrap composite feedstock can be obtained.
Keywords Recycling, composite scrap, catalytic depolymerization, carbon fiber composites, fiber tensile strength, thermoplastic, thermoset