The effect of reaction conditions on the grafting parameters during the grafting of methacrylamide (MAM) onto guar‐gum (GOH) using potassium chromate/malonic acid redox pair was studied under nitrogen atmosphere at different temperatures. On increasing the chromate ion concentration (from 3.5×10–3 mol·dm–3 to 20.0×10–3 mol·dm–3) grafting parameters were found to increase. Grafting ratio, efficiency, and add on were found to increase with the increase in malonic acid concentration from 3.5×10–3 mol·dm–3 to 10.0×10–3 mol dm–3. It was observed that maximum efficiency was obtained when the monomer concentration was 20.0×10–3 mol·dm–3. With increasing hydrogen ion concentration, grafting parameters were found to increase. Homopolymer concentration, however, was found to decrease with increasing hydrogen ion concentration. Optimum temperature and time for grafting of MAM onto guar gum were found to be 35°C and 120 min respectively. The graft copolymer was characterized by IR spectroscopy and thermogravimetric analysis.

No abstract

No abstract

ABSTRACT:The effect of reaction conditions on the grafting parameters during the grafting of acrylamide (ACM) onto guar gum (GOH) by using a Cu ϩ2 -mandelic acid (MA) redox couple was studied. On increasing the Cu ϩ2 ion concentration (0.5 ϫ 10 Ϫ2 to 1.0 ϫ 10 Ϫ2 mol dm Ϫ3 ), an increase in total conversion of monomer, grafting ratio, efficiency, and add on was observed. Grafting ratios increased with an increase in concentration of mandelic acid and reaches its maximum value at 0.8 ϫ 10 Ϫ2 mol dm Ϫ3 . It was observed that grafting onto guar gum takes place efficiently when monomer and hydrogen ion concentrations are 20.0 ϫ 10 Ϫ2 and 2.2 ϫ 10 Ϫ2 mol dm Ϫ3 , respectively. Optimum temperature and time for obtaining a maximum grafting ratio and efficiency was found to be 35 Ϯ 0.2°C and 2 h, respectively. The plausible mechanism of grafting was suggested. The graft copolymer was characterized by infrared spectroscopy and thermogravimetric analysis.