Vegetable Oil-based Hyperbranched Polyols in Flexible Foams

Novel polyols were synthesized by controlled polymerization of hydroxylated fatty acids from methyl soyate. Polymerization of methyl esters of hydroxy fatty acids gives a hyperbranched (HB) product with different content of hydroxyl groups depending on the degree of conversion. Molecular weights, functionality and hydroxyl equivalent of polyols can be controlled by controlling the degree of conversion but also using monofunctional components. A range of hyperbranched polyols with acceptable viscosities and functionalities, suitable for flexible applications, was obtained by stopping the reaction at different degrees of conversion. A polyol with 60% of hydroxylated soybean fatty acid methyl esters and 40% of methyl esters from castor oil was selected for detailed analysis and was used in flexible foams. Monte-Carlo simulation of the polymerization of hydroxylated methyl soyate gave molecular weights and distributions which were compared with experimental values. Flexible foams were obtained with 65% of HB polyol in a mixture with a petrochemical triol. Increasing concentration of the HB polyol improved load bearing properties but decreased mechanical strengths and in particular tear strength.