Urethane-Forming Reaction Kinetics of Natural Oil Polyols Versus Polyether Polyol

摘要

Urethane-forming reaction kinetics of isocyanate with natural oil polyols (NOPs) were compared to that of the petroleum based polyether polyol. NOPs in this study included a polyol synthesized from palm olein and castor oil, both containing pendant hydroxyls. Polyether polyol is a triol with ethylene oxide end groups, and therefore it contained a mixture of primary and secondary terminal hydroxyl groups. The non-catalyzed urethane forming kinetics study in toluene shows lower activation energy for both the synthesized NOP and naturally occurring castor oil compared to terminal hydroxyls of the polyether polyol. The kinetic results show higher reactivity of NOP with isocyanate in the non-catalyzed reaction in toluene at low temperatures, which was correlated with faster gel time in bulk polymerization. However, in toluene the reactivity of polyether polyol with isocyanate increases at a faster rate with temperature, and the polyether polyol showed higher response to organotin catalyst. The results indicate that the relative urethane-forming reactivities of NOPs compared to polyether polyols are not necessarily lower, and in fact under certain conditions can be higher, which needs to be taken into consideration during the incorporation of NOPs in polyurethane formulations.