Effect of trans-Polyoctenylene on Crosslink Structure of NR and SBR Using Solid State 13C NMR Spectroscopy and RPA 2000

Abstract

Abstract The use of petroleum oil as a processing aid is well established in the rubber industry. However, it has certain demerits when used in a critical rubber compound. To overcome this and to get certain other advantages, new non-conventional processing aids (solid in nature) are preferred. trans-Polyoctenylene (TOR) is one of them which is crosslinkable with sulfur and accelerator. The effect of TOR on natural rubber (NR) and styrene—butadiene rubber (SBR) vulcanizates has shown that the retention (%) of network properties at high temperatures, after aerobic and anaerobic aging, is better with incorporation of TOR in conventional vulcanization (CV) curing systems. This has been attributed to the change of network to a more efficient-like system. The purpose of the present work is to establish the change of network structure/crosslinks and their kind and distribution in NR and SBR, with incorporation of TOR followed by a spectroscopic study of the vulcanizate. The study is extended to different crosslinking systems (CV, efficient vulcanization (EV), and semi-EV (SEV) with respect to NR and SBR) considering the effect of anaerobic aging on the vulcanizates. Crosslink distribution (in CV and EV) and network structural change after aging has been explained by a suitable mechanism. Elucidation of crosslink structure of SBR vulcanizates by NMR and estimation of chemical crosslink density by the Rubber Process Analyzer (RPA 2000) are key points of this study.