Effect of Microwave Assisted Chemical Recycling Process on Surface Properties and Mechanical Performance of Recycled Carbon Fiber

In this work, the carbon fiber reinforced polymer (CFRP) composite waste was recycled using the microwave-assisted chemical recycling (MACR) technique. The technique comprises the use of green chemicals (H₂O₂ and CH₃COOH) in equal proportions coupled with microwave heating at 720 W for 180 s in a step as the optimum parameters. The recycling resulted in a 99% epoxy degradation rate with an 8.20% decline in ultimate tensile strength (UTS) and 29% increment in interfacial shear strength (IFSS) for the recycled carbon fiber (RCF). The scanning electron micrograph (SEM) and atomic force microscopy (AFM) scan showed a slight increase in surface asperities on the RCF surface confirming minimal damage post recycling. Surface roughness and mechanical properties correlation for RCF showed that R_a value of 3.85 nm was optimal at which both UTS and IFSS for RCFs were optimum. The X-ray photoelectron microscopy (XPS) analysis showed the attachment of polar functional groups (COOH, C–O–C/C–O) and an increase in oxygen content on RCF confirming oxidation of the RCF during recycling. Additionally, the energy consumed during recycling was found to be 6.23 MJ/kg of CFRP waste, making it a sustainable and highly energy-efficient technique compared to various existing recycling methods.

Graphical Abstract