GRAFT-POLYMERIZATION OF METHACRYLIC-ACID ON STARCH AND HYDROLYZED STARCHES

Hydrolysis of maize starch with HCL was studied under various conditio ns with a view to obtaining starches having different molecular sizes. To this end, the original starches and hydrolyzed starches derived fr om them were independently graft-copolymerized with methacrylic acid ( MAA) using KMnO4/citric acid as initiator. Thus the molecular weight o f the polymeric backbone of starch and the substituents present on the m could be controlled and, as a consequence, polymeric materials for s pecific utilization, such as sizing of cotton textiles, could be devel oped. Results obtained indicate the following: (a) the specific viscos ity of starch decreases and its solubility increases after hydrolysis; (b) the graft yield (expressed as meg -COOH/100 g starch) increases w ith increasing extent of hydrolysis; (c) the specific viscosity decrea ses as the graft yield increases up to a certain limit, beyond which i t increases; (d) the percent solubility of hydrolyzed starches decreas es with increasing graft yield. On the other hand, it was found that c opolymers derived from hydrolyzed starches function better as sizing a gents than the original starch, hydrolyzed starches lying between the two.