Reactivity of Modified Starches with Isocyanates

Various substituents were added onto starch by means of esterification or etherification so that their effect on reactivity of starch with isocyanates in a nonpolar solvent could be studied. Maximum reactivity of the modified starches was achieved when the degree of substitution (D.S.) was about 0.7. Cured urethane plastics made from formulations containing 20 % of the starch derivatives demonstrated maximum breaking energy at D.S. 0.7.