Evaluation of Recycled Carbon Black (r-CB) Based on Styrene Butadiene Rubber, Natural Rubber and Nitrile Rubber Compounds

The enormous accumulation of used tyres has long been a threat to the environment. Pyrolysis is a process of chemically decomposing organic materials at elevated temperatures above 430°C in the absence of oxygen. Pyrolysis can be used to reprocess the tyres into fuel gas, oils, solid residue (char) and low-grade carbon black, which cannot be used in tyre manufacture. Rubber compounds containing r-CB were prepared based on Styrene Butadiene Rubber, Natural Rubber and Nitrile Rubber. Specific formulations were selected for each of the rubber. Natural Rubber was mixed with r-CB to produce pre-cured tread compound for retreading, Nitrile Rubber was mixed with r-CB to produce hose and seals compounds, and finally, r-CB was compounded in accordance to the Standard Test Methods for Styrene-Butadiene Rubber Recipe and Evaluation Procedures. The quality and performance of r-CB in these rubber compounds were compared with the commercial virgin carbon black. The results show that r-CB matches the quality of virgin carbon black such as High Abrasion Furnace (N330) and Fast Extrusion Furnace (FEF, N550) in terms of hardness, tensile strength, abrasion resistance and other relevant physical properties. The prospects of r-CB are very bright and promising. The challenges ahead are to maintain high quality of r-CB, to be competitive in cost in relation to virgin carbon black.