Synthesis and physicochemical properties of graft copolymer of corn starch and acrylamide

Graft copolymerization of corn starch with acrylamide using ceric ammonium sulphate/citric acid initiation system has been studied under nitrogen atmosphere in aqueous medium. The grafting parameters are favored by increasing monomer concentration and reaction time but are affected by higher concentration of initiator and high temperature. The optimum conditions established for grafting were as follows: the concentration of initiator, 0.003 mol/L; the concentration of citric acid, 0.03 mol/L; monomer/starch, 1:1 feed ratio (w/w); reaction time, 3.0 h; and temperature, 35 degrees C. The extent of grafting was examined by Fourier transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Both swelling power and solubility increased with the increase in temperature. Graft copolymerization increased swelling power and reduced solubility. Rapid visco-analyzer pasting profile was studied. Graft copolymerization of corn starch results in high pasting temperature, high peak viscosity, and setback as compared with native starch. Breakdown was retarded at low percentage grafting (6.60%) but increased at high percentage grafting (60.27%).