Synthesis of biopolyols by mild oxypropylation of liquefied starch and its application to polyurethane rigid foams

The liquefaction of starch in the presence of commercial polyol resulted in liquefaction products (LPs) with much lower hydroxyl values compared to those resulting from glycerol liquefaction. With the use of the obtained LPs (as initiators) and a catalytic amount of potassium hydroxide, oxypropylation was conducted under mild conditions (at 120 degrees C, inner pressure generation of <0.2 MPa). Urethane resin foams were prepared from the obtained biopolyols. The reactivities of the biopolyols toward isocyanates were almost the same as those of commercial polyols. The physical properties of the obtained foams were as good or better than the ones obtained with the commercial polyols, including the sucrose/glycerol polyol GR-84T. The biomass content values of the foams prepared with the biopolyols ranked among the highest in the world. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013