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 × 10−3 to 24.0 × 10−3 mol dm−3) and glycolic acid concentration (4.4 × 10−3 to 7.6 × 10−3 mol dm−3). On increasing the hydrogen ion concentration from 4 × 10−3 to 12.0 × 10−3 mol dm−3, grafting ratio, efficiency, add on and conversion were increased. Maximum grafting was obtained when guar gum and N,N′-dimethylacrylamide concentration were 1.0 × 10−2 g dm−3 and 14.0 × 10−2 mol dm−3, respectively. An increase in temperature from 25 °C to 45 °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.