Abstract: Plastic waste recycling is a focal point in today's sustainable development efforts. Improper disposal can lead to secondary pollution, posing threats to the environment and human health. In this study, we aim to recycle waste epoxy resin and glass fiber-reinforced epoxy resin composites via an electroless plating and a carbonization process, to design high-value-added carbon materials for microwave absorption. By pulverizing solid waste and introducing magnetic metal nanoparticles onto its surface, a composite carbon material capable of excellent microwave absorption performance was successfully developed. Specifically, doping nickel particles into carbon materials derived from glass fiber/epoxy resin achieved a wide effective absorption bandwidth (EAB) of 5.9 GHz with a matching thickness of 1.9 mm, covering nearly the entire Ku band, and achieving a minimum reflection loss (RL_min) of -36 dB simultaneously. The superior absorption performance is attributed to multiple reflections or scattering of electromagnetic waves within the material, as well as conduction and magnetic losses, dipole and interfacial polarization effects. These results demonstrate that through rational design and optimization, waste epoxy and waste glass fiber-reinforced epoxy resin-based composite materials can be effectively recycled into high-performance microwave absorbing materials, offering a straightforward and efficient pathway for waste resource utilization.

Key words: Epoxy resin, Carbonization, Microwave absorption, Plastic waste recycling