Maintaining electromagnetic interference shielding and flame-retardant performance of recycled carbon fiber-reinforced composites under multiple pyrolysis recycles

Abstract

The widespread usage of carbon fiber-reinforced polymer composites imposes serious challenges in disposing of end-of-life and wasted products. Pyrolysis recycling has become an efficient strategy to decompose the resin matrix and extract the fiber, while the bottleneck lies in maintaining the structural integrity and physicochemical properties of the recycled fibers, along with reconstructing corresponding composites with performance efficiency. In this work, a two-step pyrolysis strategy is demonstrated to decompose the resin matrix and remove the carbon residues without damaging the internal structure of the recycled carbon fiber felts (rCFFs), followed by surface modification to facilitate the reconstruction of rCFFs-reinforced phenolic resin composites. The composites achieve remarkable electromagnetic interference (EMI) shielding performance in the X band with maximum EMI shielding effectiveness value of 70.5 dB, along with impressive flame-retardant performance under a high heat flux of 50 kW/m2. Besides, more than 80 % EMI shielding effectiveness is maintained after 10 pyrolyzing cycles by optimizing the pyrolysis parameters. Catering to maintaining the intrinsic properties of the recycled carbon fibers by proposing comprehensive recycling strategy, the synthesis of rCFFs-based materials is of great significance for promoting the substitution of pristine EMI shielding counterparts and the practical reutilization of carbon fiber resources.