Cu+2 mandelic acid redox pair initiated graft copolymerization acrylamide onto guar gum

The effect of reaction conditions on the grafting parameters during the gra fting of acrylamide (ACM) onto guar gum (GOH) by using a Cu+2-mandelic acid (MA) redox couple was studied. On increasing the Cu+2 ion concentration (0 .5 x 10(-2) to 1.0 x 10(-2) mol dm(-3)), an increase in total conversion of monomer, grafting ratio, efficiency, and add on was observed. Grafting rat ios increased with an increase in concentration of mandelic acid and reache s its maximum value at 0.8 x 10(-2) mol dm(-3) It was observed that graftin g onto guar gum takes place efficiently when monomer and hydrogen ion conce ntrations are 20.0 x 10(-2) and 2.2 x 10(-2) mol dm(-3), respectively. Opti mum temperature and time for obtaining a maximum grafting ratio and efficie ncy was found to be 35 +/- 0.2 degrees C and 2 h, respectively. The plausib le mechanism of grafting was suggested. The graft copolymer was characteriz ed by infrared spectroscopy and thermogravimetric analysis. (C) 1999 John W iley & Sons, Inc.