Effect of Soybean Oil Structure on the Structure and Properties of Polyols and Polyurethanes

摘要

Vegetable oils are very heterogeneous raw materials consisting of triglycerides with different combinations of fatty acids. Soybeanoil has essentially five fatty acids but they may form 35 combinations in triglycerides with unsaturation varying from zero to eightdouble bonds per triglyceride. The most abundant species are ones with four double bonds followed by six and five double bonds. Ifhydroxyl groups are introduced at the position of double bonds, the same or at least related distribution of functionalities will beobtained in the polyols, and tetrafunctional species would dominate. Lowering hydroxyl number increases heterogeneity and may alsoincrease the amount of non-functional species. Gelation of polyfunctional systems is related to the weight average functionality, fw,not number average functionality, fn, which is often reported. However, while fn can be experimentally obtained from number averagemolecular weight and hydroxyl number (equivalent weight), weight average must be calculated from the composition. In thispresentation we discuss the effect of functionality distribution in polyols of different hydroxyl numbers, gelation properties andmechanical properties of polyurethanes cured with MDI.