An overview on the recycling of waste ground tyre rubbers in thermoplastic matrices: Effect of added fillers

The increasing generation and accumulation of waste tyres threaten the ecosystem. Waste tyre landfills create potential fire hazards, environmental pollutions, and threats to human health, as waste tyre pileups harbour rodents, mosquitoes and reptiles, generating harmful diseases. Moreover, there is a great economic loss associated with the disposal of waste tyre rubbers. Therefore, this approach is not sustainable, making the recycling of waste tyre rubber necessary. Accordingly, several recycling strategies are being developed to obtain value-added waste tyre rubber. One of such strategies, which is of environmental conservative and consumes an appreciable quantity of the waste tyres, is the blending of thermoplastics with ground tyre rubber (GTR). However, achieving homogenous dispersion of GTR in matrix poses a great challenge owing to little or no affinity between GTR and thermoplastics. To overcome this problem, surface treatments of GTR, compatibilizers, additives, and energy treatments are used. Most recently, incorporation of rigid nanoparticles with or without combination of other techniques are adopted to facilitate GTR dispersion. In this review, we discuss the recycling of GTR in thermoplastic matrices. Specific attention was paid to the effect of fillers, and more particularly nanofillers, on the dispersion of GTR within thermoplastic matrices for achieving competitive materials.