Seng Soi Hoong

Urethane-forming reaction kinetics of natural oil polyols versus petroleum-based polyether polyol

Urethane-forming reaction kinetics of isocyanate with natural oil polyols (NOPs) with pendant reactive hydroxyls was compared to that of the petroleum based polyether polyol with terminal hydroxyls. The non-catalyzed urethane forming kinetic study in toluene shows lower activation energy for pendant hydroxyls of the synthetic and naturally occurring NOP compared to terminal hydroxyls of the polyether polyol. At low temperatures in the non-catalyzed reaction in toluene, the NOPs showed higher reactivity with isocyanate, which was correlated with faster gel time in bulk polymerization. However, in toluene, the reactivity of polyether polyol increases at a faster rate with temperature, and in toluene and bulk reactions the polyether polyol shows higher response to dibutyltin dilaurate catalyst. The results indicate that relative reactivities of NOPs compared to polyether polyols are not necessarily lower in urethane forming reactions, and in fact under certain conditions can be higher, which needs to be taken into consideration during the incorporation of NOPs in polyurethanes.

Synthesis and characterization of polyurethanes made from copolymers of epoxidized natural oil and tetrahydrofuran.

Polyols were synthesized from epoxidized natural oils and tetrahydrofuran through ring opening copolymerization catalyzed by Lewis acid. The properties of these polyols depend on the type of natural oils as well as the reaction conditions (monomer concentration, catalyst amount, reaction temperature and reaction time). These polyols were evaluated as a raw material for making polyurethane (PU) in order to understand the structure-property relationship between a natural oil and PU made from it. The tensile test analysis shows that the incorporation of natural oil moiety into the PU polymer network improves the elasticity of these PU samples when compared to a benchmark PU sample. In addition, the PU samples made from palm oil and soybean oil based polyols exhibit better tensile strength than benchmark PU. These polyols samples are suitable for making elastomeric PU, where high flexibility (high elongation at break) of PU is a common requirement.