Shellac as a Multifunctional Additive (MFA) in a Typical Truck Tyre Sidewall Compound

Abstract

This study reports some unexplored features of naturally occurring Indian shellac present in a typical truck tyre sidewall compound, at low doses with the intention of replacing stearic acid in the formula. The chemical characterization of shellac was determined using Fourier transform infrared (FTIR) spectroscopy, along with information from earlier published reports, revealing the presence of different fatty acids, alcohols, esters and quinone-based dyes. The substitution of stearic acid with shellac shows that 50% replacement of the acid with shellac obtained comparable rheometric and physical properties with the control compound. The presence of different components in shellac further helped to improve ageing and reversion resistance. The volatile loss from shellac is much lower compared with commercial stearic acid. Some essential properties for sidewall application such as extrudate shrinkage and die swell behaviour were also found to be suitable when 50% of the commercial stearic acid was replaced with shellac in the formula.