Waste-Derived Reinforcing Fillers in Guayule and Hevea Natural Rubber

As the world moves toward a sustainable bio-economy, researchers are developing replacement biomaterials for petroleum-derived products, with the goal of achieving comparable or superior performance. Non-sustainable reinforcing and diluent fillers are used extensively in the rubber industry. We have investigated the effect of the particle size of fillers made from large-scale food processing wastes as partial and complete replacements of petroleum-derived carbon black. The interaction of the fillers with the natural rubber matrix was different in guayule and hevea rubber, and led to differences in overall reinforcement achieved with the waste-derived fillers. Superior reinforcement of guayule rubber may reflect a combined synergistic reinforcing effect of carbon black particles, which possess a strong polymer-filler interaction, with the formation of a unique network between the rubber and the waste-derived materials, not attained with Hevea rubber. Unusual combinations of mechanical properties were achieved with both types of rubber. Also, we have shown that micro sized fillers are effective reinforcing fillers, and these can be produced at a far lower cost than their nano-particle versions.