Tough thermosetting polyurethanes and adhesives from rubber seed oil by hydroformylation

Abstract

ABSTRACTRubber seed oil (RSO), extracted from the seeds of rubber trees, is inedible oil with high free fatty acid content. In order to add value to RSO, we prepared a polyol with primary OH groups via hydroformylation/hydrogenation. Free hydroxy fatty acids formed in the process were utilized as reactive diluents, viscosity reducers, and adhesion promoters through hydrogen bonding with the substrate. The structures of the oil and polyol were analyzed using a range of analytical methods. The polyol had a hydroxyl number of 244 mg KOH g−1 and an acid number of 21 mg KOH g−1. The polyurethane prepared from this polyol and diphenylmethane diisocyanate was a highly crosslinked, tough material with a glass transition at 44 °C, high tensile strength and elongation, and attractive electrical properties. When used as a wood adhesive, it displayed extraordinary shear strength characterized by substrate wood failure rather than cohesive failure of the polymer. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48509.