Investigating the synergism and partial replacement of carbon black by cellulose nanofibers in natural rubber-based tyre tread composites

Abstract

Alleviating the carbon footprint by utilizing bio-based fillers to develop sustainable tyre tread composites is a promising and innovative approach. Our research presents sustainable nanocomposites that utilize cellulose nanofiber (CNF) as reinforcing filler for natural rubber (NR) based truck, bus and radial tyre (TBR) tread composites. The choice of cellulose nanofibers, with their renewable nature, biodegradability, lightweight, and superior mechanical properties, to partially replace carbon black (CB) in different ratios underscores the innovative nature of our approach. Although there are a few studies focused on replacing CB with nanocellulose, a comprehensive study is necessary to optimize the loading of CB and CNF by varying the replacement ratios, thereby fully harnessing the potential of CNF. We have explored the synergism between CB and CNF and optimized CB content in the hybrid nanocomposite, demonstrating a reduction in the amount of CB in tyre tread composites. The performance of the hybrid nanocomposite is shown to be highly dependent on CNF and its concentration, as evidenced by morphological, static and dynamic mechanical properties. The increase in tensile strength and modulus (an increase of 413% at 100% elongation) after partially replacing CB by CNF of half the concentration of replaced CB indicates good synergism and better reinforcing ability of CNF. The remarkable decrease in rolling resistance (34%) and the improvement in wet grip properties after partially replacing CB with CNF is quite promising for tyre tread applications to replace CB with CNF at higher ratios. The lower surface roughness values observed for 2.5 phr CNF-loaded hybrid nanocomposite from AFM analysis indicated better CNF dispersion at lower loadings. The development of these nanocellulose-based tyre tread composites not only offers a sustainable solution but also imparts bioeconomy concepts to tyre industries, reducing their dependence on non-renewable petroleum-based products and opening up new circular economic opportunities.