Copolymers of tetrahydrofuran and epoxidized vegetable oils: application to elastomeric polyurethanes

Abstract

The Lewis acid ring-opening of epoxidized vegetable oils (EVO's) in the presence of tetrahydrofuran (THF) gives rise to polyether polyol co-polymers p(THF-stat-EVO). The effect of Lewis acid, vegetable oil substrate (epoxidised methyloleate EMO, epoxidised cocoa butter ECB, and epoxidised palm oil EPO) and conditions (concentration, temperature and time) on the molecular weight, polydispersity, hydroxyl value and thermal properties of the p(THF-stat-EVO) macromonomers was determined. Elastomeric polyurethanes were prepared from p(THF-stat-EVO) macromonomers and MDI and their mechanical and thermal properties determined. The properties of the polyurethane derived from p(THF-EPO) were compared to that derived from the homopolymer of epoxidised palm oil (EPO) prepared by Lewis acid ring-opening in the absence of THF. The co-polymer incorporating THF gave rise to a material with significantly greater tensile strength [p(THF-EPO-MDI) = 9.1 MPa, p(EPO-MDI) = 1.5 MPa] and elongation at break [p(THF-EPO-MDI) = 425%, p(EPO-MDI) = 70%] with little compromise on thermal stability [p(THF-EPO-MDI) T_decomp10% = 378 °C, T_decomp50% = 414 °C, p(EPO-MDI) T_decomp10% = 379 °C T_decomp50% = 424 °C].