Green Approaches in Rubber Recycling Technologies: Present Status and Future Perspective

As a consequence of massive production and consumption of rubbers, rubber blends, and rubber composites for myriad applications, elastomeric products have enormously accumulated and become an environmental threat. The disposal and burning of rubber wastes have been banned because of environmental and economic reasons. By contrast, a great deal of attention has been directed toward strategies enabling recycling and reuse of rubbers. Basically, conventional recycling methods suffer from several drawbacks such as the formation of dust, fumes, and toxic gases in the air, as well as contamination of underground water resources. Thus, green and sustainable formulations and processing methods nowadays are of priority and importance. Taking advantage of sustainable development horizons, scientific and technological aspects of waste rubber management such as processing techniques, properties of the resulting products, industrial applications, and compatibilization with other materials such as thermoplastics, thermosets, and rubbers are herein reviewed and discussed. A particular emphasis is placed on reactive extrusion as a highly flexible in situ compounding method enabling innovations and taking care of sustainability concerns. Finally, the current status of green rubber recycling and future opening doors ahead of this technology are highlighted.