Influence of polyurethane adhesives on tensile and compressive properties of ground rubber composites

Rubber from End-of-Life Tires (ELT) is often used as secondary raw material for composites. Polyurethane adhesives are widely employed in such formulations, since they bind to rubber particles effectively. In this study Ground Tire Rubber of passenger car ELT and truck tire tread buffings were used as feedstock. Toluene diisocyanate was used as a hardener for polyether-based prepolymer resin. Hardener amounts, curing durations and temperatures were varied to produce composite sheets. Scanning electron microscopy showed differences in the type of voids within the sheet and suggested that the amount of adhesive, surface wetting and curing regime could affect the composite structure significantly. Tensile and compressive properties of the composites were more dependent on the adhesive amount than curing temperature variation below 60°C. Better understanding how to control physical and mechanical properties of such composites will significantly contribute to value-added utilization of ELT as well as environmental and societal benefits.