Influence of microwave treatment on the tensile properties, fracture behaviour and water absorption of ground tyre rubber/epoxy composites

The incorporation of solid waste, tyre-derived rubber, into epoxy resin matrices presents a sustainable strategy for recycling end-of-life tyres while enabling the development of advanced composite materials and structural adhesives. This work examines the influence of microwave (MW) irradiation parameters, specifically power and exposure time, on the performance of ground tyre rubber (GTR)/epoxy composites. GTR particles were subjected to MW treatment at 630 W and 810 W for durations ranging from 20 to 120 s. The epoxy system was prepared using diglycidyl ether of bisphenol-A and cycloaliphatic amine (EPH 555). Mechanical behavior was characterized through tensile and fracture toughness testing, while physical properties were assessed via water absorption, fracture surface morphology, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and Fourier transform infrared (FTIR) analyses. Microwave treatment modified the carbon (C)–sulphur (S) bond of GTR without disrupting its primary chemical backbone. Compared with untreated GTR, MW-treated composites exhibited higher tensile strength (11-15%) and elastic modulus (12-15%), albeit at the expense of reduced fracture toughness. In comparison with neat epoxy, however, GTR incorporation improved fracture toughness, attributed to crack pinning mechanisms, while diminishing tensile properties. Furthermore, GTR addition lowered water absorption, with MW treatment imparting additional benefits, improving water resistance under tensile loading. These findings highlight the potential of recycled tyre rubber as an effective filler for epoxy-based composites, offering both environmental and performance advantages.