GRAFT-POLYMERIZATION OF ACRYLIC-ACID ONTO STARCH USING POTASSIUM-PERMANGANATE ACID (REDOX SYSTEM)

Graft polymerization of acrylic acid (AA) onto rice starch using potas sium permanganate/ acid redox system as initiator was investigated. Wh en starch was reacted with KMnO4 solution, MnO2 was deposited onto sta rch. The dependence of MnO2 amount deposited was directly related to K MnO4 concentration. Subjecting the MnO2-containing starch to a solutio n consisting of monomer (AA) and acid (citric, tartaric, oxalic and hy drochloric acid) formed poly(AA)-starch graft. copolymers. The graft y ield, expressed as meg COOH/100 g starch, was measured by the amount o f MnO2 deposited, AA concentration, material-to-liquor ratio, kind and concentration of acid, as well as temperature and duration. Finally, the newly prepared poly(AA)-starch graft copolymers were applied to co tton textiles to determine their suitability as sizing agents. The hig hest graft yield was obtained with citric acid and the least with hydr ochloric acid, with tartaric and oxalic acid in between. The graft yie ld increased by increasing the concentration of acid to a certain conc entration beyond which grafting leveled off. A similar trend was obser ved when the magnitude of grafting was related to the amount of MnO2 d eposited. The graft yield increased by increasing the polymerization t emperature from 30 degrees to 50 degrees C. Increasing the temperature to 60 degrees C is accompanied by decreased grafting. On the other ha nd, fabric samples sized with poly(AA)starch graft copolymers acquire higher tensile strength, elongation at break, and abrasion resistance than that sized with native rice starch, i.e., poly(AA)-starch graft c opolymers serve as good sizing agents for cotton textiles. A tentative mechanism for grafting rice starch with AA using the KMnO4/acid redox system was elucidated. (C) 1995 John Wiley and Sons, Inc.