Graft co-polymerization of 2-acrylamido-2-methyl-1-propane sulphonic acid onto guar gum by the bromate/mandelic acid redox pair

Abstract

Guar gum has been modified by grafting 2-acrylamido-2-methyl-1-propane sulphonic acid (AMPS) onto guar gum in aqueous medium. The graft co-polymerization reaction was studied under different experimental conditions, such as varying monomer concentration, redox pair concentration, backbone concentration, hydrogen ion concentration, time of reaction and temperature. It has been observed that grafting ratio, add on, conversion and rate of grafting decrease on increasing the bromate ion concentration. A similar trend has been observed with hydrogen ion concentration. The grafting ratio, add on, conversion and rate of grafting have been found to increase with mandelic acid concentration. On increasing the AMPS concentration in the concentration range 2.0 × 10 −2 to 8.0 × 10 −2 mol dm −3 , the grafting parameters show increasing trend. However, increase in guar gum concentration decrease the grafting ratio, add on and rate of grafting while conversion increases with increase in guar gum concentration. All the grafting parameters show increasing trend with time and the optimum temperature has been observed as 35 • C. The graft co-polymer has been characterized by infrared spectroscopy and thermogravimetric analysis.