Influence of biochar and carbon black on natural rubber mixture properties

A biochar made by hydrothermal carbonisation treatment of hardwood waste biomass was compared with traditional carbon black (CB) filler and their impact on the electricity consumption of the rubber mixture, vulcanisation and mechanical properties was examined. Two sets of experiments were conducted, following the same procedure and recipe and using different contents (parts per hundred) of biochar or CB as a filler (0, 10, 20, 30, 40 and 50 phr). The low content of different fillers (up to 20 phr) showed a similar electricity consumption for rubber mixing. Further increase of filler content caused a superior impact on energy consumption value for prepared rubber mixtures with CB. An influence of filler type and content on the vulcanisation properties (maximum and minimum torque, scorch time and cure rate index) was detected. With regard to hardness values, tensile strength, elongation at break and tensile stress were affected by the different reinforcing agents and their content. The assessed data revealed that CB as a filler might potentially be replaced with environmentally friendly and sustainable fillers up to 30 phr, enabling similar rubber vulcanisation and mechanical properties. The overall outcome of this study emphasised the significance of the results obtained for strict environmental protection demands in the rubber industry. (c) 2022 Society of Industrial Chemistry.