Hybrid fillers of lignin and carbon black for lowering of viscoelastic loss in rubber compounds

This study investigates novel hybrid fillers for lowering of viscoelastic dissipation in rubber compounds by exploiting non-covalent interactions between lignin and carbon black (CB). Lignin is naturally occurring three-dimensional amorphous polymer consisting of phenyl propane units with hydroxyl, methoxy, and carbonyl substitutions and is capable of producing non-covalent interactions via π–π stacking with CB particles. The hybrid fillers are obtained by precipitating lignin from solutions onto carbon black particles. The fractal nature similar to CB particles and the presence of lignin coating layers on CB particles are confirmed by electron microscopy images. The coating layers are promoted by strong π–π interactions as revealed from Raman spectroscopy and 1H spin-lattice relaxation data and supported by a drop in zeta potential values. The hybrid fillers show much less networking than CB and reduce the viscoelastic dissipation in model rubber compounds by as much as 10% in comparison to the compounds of only CB.