Abstract
This study investigated the effect of the diene backbone structure on the tribological response to maleic anhydride (MAh) functionalization by comparing polyisoprene (PIP), polybutadiene (PB), and their MAh-modified derivatives. By introducing the same MAh modifier at the same feed ratio into both backbones and matching the bulk viscosities, the effect of backbone structure was examined under controlled viscosity conditions. Dynamic viscoelastic measurements showed that the complex viscosity η* was comparable for all the sample oils, minimizing the influence of bulk viscosity. PB yielded lower friction than PIP, even without functionalization, which indicates a backbone-structure effect. The MAh functionalization reduced the friction in both systems and tended to decrease the wear-scar volume, with more pronounced effects in PB. The PB–MAh derivative exhibited the lowest friction coefficient and the smallest wear-scar volume. X-ray photoelectron spectroscopy C1s analyses showed small differences in spectral shape and the relative contributions of fitted components between the MAh-functionalized and corresponding nonfunctionalized samples, but no distinct C1s component specifically attributable to MAh was observed. The presence or absence of CH3 substitution on the diene backbone thus affects the friction and wear responses to MAh functionalization under the considered conditions.
