The effect of lignin dispersion on abrasion resistance in polybutadiene rubber (BR)

The tyre industry is the largest rubber user globally and it uses reinforcing fillers like carbon black and silica to improve mechanical properties. Sustainable alternatives, such as biobased lignin, are needed. In this study, kraft lignin is mixed with polybutadiene rubber at different temperatures to achieve various dispersion rates. Lignin dispersion is measured from polished samples using scanning electron microscopy, and mechanical properties and abrasion resistance are tested. Results show that improved lignin dispersion enhances mechanical properties and abrasion resistance significantly, as the best dispersed compound have 89% smaller abrasion loss than the poorly dispersed compounds. However, the results of the lignin compounds are still poorer than the ones reinforced with carbon black. Abrasion surface analysis reveals poor rubber-filler interaction, with lignin particles leaving holes in the rubber matrix. Better dispersion reduces wear rate and surface roughness. Highly dispersed lignin can reinforce polybutadiene rubber, however lower mixing temperatures are needed to avoid negative effects on elongation at break. Improved rubber-filler interaction could further enhance lignin's reinforcing effect.