Achieving ultra-tear resistant high-performance natural rubber nanocomposite via bio-inspired lignocellulosic compatibilization

Elastomers which are strong, tough, and resistant to tearing, are highly attractive for engineering applications such as conveyer belts, high-performance seals, tires, and soft robotics. Enhancing these properties for natural rubber materials is possible by utilizing nanoscale fillers, however the nanocomposite approach remains challenging because (a) nanofillers can impede latex molecular crosslinking, and (b) reduce the material's inherent elasticity and compliance. This study demonstrates an approach to prepare ultra-strong, tear-resistant natural rubber nanocomposites using cellulose nanofibers decorated with nanoscale lignin. The reinforcement of latex with 0.1 wt% cellulose nanofibre compatibilized with 0.5 wt% lignin resulted in a 256% improvement in tear strength, 95% in tensile strength, and 50% in toughness, while retaining the elongation at break. Such a simultaneous improvement in tensile and tear properties has not been previously achieved through the latex casting method with any other fillers, and herein it is attributed to the nanoscale reinforcement efficiency of nanofibre coupled with enhanced interfacial adhesion between nanofibers and NR latex with the introduction of nanoscale lignin. This compatibilization approach has also resulted in improved resilience in the nano-composites, as evidenced by the cycling loading and unloading analysis.