SYNTHESIS, CHARACTERIZATION AND PROPERTIES OF POLYACRYLAMIDE-STARCH COMPOSITES

Polyacrylamide-starch composite was prepared by polymerization of maiz e or rice starch with acrylamide (Aam) using potassium permangante/cit ric acid initiation system. Major factors affecting the polymerization reaction were studied with a view to discover appropriate conditions for preparation of the composite. Results obtained imply that the tota l conversion (monomer converted to homopolymer and graft) increases by increasing concentrations of potassium permanganate from 0.5-0.20%, c itric acid from 0.1-0.15 and acrylamide from 10-30% ows. Polymerizatio n can easily be carried out at 40 degrees C for 6 min at pH 4 using a material to liquor ratio 1:25 under a stirring rate of 350 rpm. The re sults further imply (a) that the apparent viscosity of the composite i ncreases by increasing Aam concentration irrespective of the rate of s hear, (b) that for 30% Aam concentration the composite consists of 77. 7% starch and 22.3% polyacrylamide of which 10.4% are grafted, (c) tha t the sizeability of polyacrylamide-starch composites is much better t han that of native starches, and (d) that the kind of starch not only determines the total conversion but also the composition of the compos ite.