Syntheses and characterisation of graft copolymers of maize starch and methacrylonitrile

Grafting of methacrylonitrile (MAN) onto dried maize starch using eerie amm onium nitrate (CAN) as an initiator has been studied gravimetrically under nitrogen atmosphere in aqueous medium. The percentage grafting is favoured by increasing monomer concentration and reaction time but is affected by hi gher concentration of initiator and high temperature. No rafting was observ ed beyond 45 degrees C. The optimum conditions established for grafting wer e: [CAN] = 0.002 mol/l which was added in molar nitric acid; [MAN] = 0.755 mol/l; reaction time, 180 min; and temperature, 35 degrees C. The graft cop olymers were analyzed by infrared spectroscopy and acid hydrolysis. The gra fting of methacrylonitrile onto starch does not alter the thermal stability of starch. The crystalline region of starch was also involved in grafting. Scanning electron microscopy showed a thick polymer coating of grafted PMA N on the starch surface. (C) 2000 Elsevier Science Ltd. All rights reserved .