Study of the Crosslinking Reaction between Epichlorohydrin and Starch

Abstract

Abstract The crosslinking of starch with epichlorohydrin under homogeneous and heterogeneous conditions has been studied with a particular view of measuring the extent of the side reaction wherein epichlorohydrin is substituted on the starch as a monoether derivative. The extent of this reaction, compared to the diether crosslink, was found to be strongly dependent on the reaction conditions (temperature, time, mole ratio of all reactants) and depending on these from 5 – 25 % of the applied epichlorohydrin is bound in the resulting product as a glycerol monoether substituent. The degree of swelling of the crosslinked starch was shown to be linearly dependent on the molar ratio of water to starch in the reaction mixture. It is shown that starch crosslinking proceeds with remarkable efficiency when epichlorohydrin is applied in the vapour phase. When crosslinking is performed under conditions which maintain the native granule structure the extent of monoether formation is about the same as for homogeneous crosslinking conditions.