Management of agricultural waste to manufacture biochar: An alternative reinforcing filler for carbon black in nitrile butadiene rubber composites

The carbon black (CB) used in rubber manufacturing and the unsafe disposal of agricultural waste are one of the causes of environmental pollution. Indeed, the production of one ton of CB produces about 2.4 tons of carbon dioxide. The conversion of these agricultural wastes into biochar (Bi) and using them as a reinforcing material is one of the trends that achieve sustainability and promote environmentally sound. Herein, the modified biochar (MBi) was obtained by chemo-mechanical treatment utilizing stearic acid for Bi which was produced from the pyrolysis of citrus trees to enhance its dispersion in nitrile butadiene rubber (NBR) composite. In addition, the present study scrutinized the influence of synergism between the MBi and CB as a filler in the NBR composites. The characterization of as-prepared samples was carried out by tracing the surface morphology, particle size analyzer, and identification of chemical bonds, as well as rheological, mechanical, aging, and electrical conductivity properties. The rheological studies showed that the optimum vulcanization time (tc90) did not significantly prolong for MBi-filled composites, which sequentially higher the benefits of the study by reducing energy consumed and thus, the process cost. In addition, the surface morphology and the mechanical data have distinguished that MBi particles were well-distributed along the matrix, as revealed by the tensile properties of the final composites. The electrical conductivity results manifested that MBi did not adversely affect the enhancement of conductivity. Whereas, the permittivity was increased due to the interfacial polarization between the filler and rubber matrix. In conclusion, the innovative filled-MBi elastomer composite would pave the way for an eco-friendly product that is valid for various applications.