Graft copolymerization of acrylic acid onto guar gum initiated by vanadium (V)-mercaptosuccinic acid redox pair

Guar gum has been modified by graft copolymerization with acrylic acid in aqueous medium using vanadium (V)-mercaptosuccinic acid redox system. The optimum reaction conditions affording maximum grafting ratio, efficiency, add on and conversion have been determined. The grafting parameters have been found to increase with increase in vanadium (V) concentration upto 1.0 x 10(-2) mol dm(-3), but these parameters decrease on further increasing the vanadium (V) concentration. On increasing the mercaptosuccinic acid concentration from 1.0 x 10(-2) to 4.0 x 10(-2) mol dm(-3) grafting ratio, efficiency and add on increase up to 2.0 x 10(-2) mol dm(-3) but decrease with further increase in mercaptosuccinic acid concentration. On varying the acrylic acid concentration from 5.0 x 10(-2) to 30.0 x 10(-2) mol dm(-3), maximum grafting ratio, efficiency and add on have been obtained at 20.0 x 10(-2) mol dm(-3). The grafting ratio, add on and conversion increase, on increasing the H+ ion concentration from 1.5 x 10(-1) to 6.0 x 10(-1) mol dm(-3). On increasing the guar gum concentration the grafting parameters increase. The grafting ratio, add on and conversion have been found to increase with time period while efficiency started decreasing after 120 min. It has been observed that %G increases on increasing the temperature up to 35 degrees C. The graft copolymer has been characterized by IR spectroscopy and thermogravimetric analysis. (c) 2006 Elsevier Ltd. All rights reserved.