Synthesis and Application of New Thickerners Part I: Preparation of Poly (Acrylic Acid)‐Starch Graft Copolymer

Abstract

Graft polymerization of maize starch with acrylic acid using potassium persulphate as free radical initiator was investigated under different conditions. Variables studied included initiator concentration, acrylic acid concentration, starch/water ratio and polymerization temperature. The carboxyl content of the grafted starch was determined and used for calculation of the grafted yield. It was found that the graft yield increases by increasing persulphate; no significant enhancement in grafting could be observed upon using higher persulphate concentrations. Grafting increases also by increasing acrylic acid concentration up to 150% (based on wt. of starch) and tends to decrease at higher concentrations. Starch/water ratio of 1:6 constitutes the optimal for maximum grafting. Raising the polymerization temperature from 25 to 43°C enhances the polymerization rate. The apparent activation energy of the copolymerization reaction amounts to 182.17 Joule/mole. Copyright © 1989 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim