Guar gum-g-N,N′-dimethylacrylamide: Synthesis, characterization and applications

The graft copolymerization of N,N'-dimethylacrylamide onto guar gum initiated by potassium peroxymonosulphate/glycolic acid redox pair in an aqueous medium was studied gravimetrically under a nitrogen atmosphere. Grafting ratio, grafting efficiency and add on increase on increasing the concentration of potassium peroxymonosulphate (8.0 x 10(-3) to 24.0 x 10(-3) mol dm(-3)) and glycolic acid concentration (4.4 x 10(-3) to 7.6 x 10(-3) mol dm(-3)). On increasing the hydrogen ion concentration from 4 x 10(-3) to 12.0 x 10(-3) mol dm-3, grafting ratio, efficiency, add on and conversion were increased. Maximum grafting was obtained when guar gum and N,N'-dimethylaciylamide concentration were 1.0 x 10(-2)g dm-3 and 14.0 x 10(-2) MOI dm(-3), respectively. An increase in temperature from 25 degrees C to 45 degrees C, the grafting ratio increases but conversion and homopolymer decrease. The optimum time period for graft copolymerization was 2 h. The graft copolymers were characterized by IR spectroscopy and thermogravimetric analysis. (C) 2013 Elsevier Ltd. All rights reserved.