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Preparation of starch–poly–glutamic acid graft copolymers by microwave irradiation and the characterization of their properties

Jingyuan Xu, Elizabeth F. Krietemeyer, Victoria L. Finkenstadt, Daniel Solaiman, Richard D. Ashby, Rafael A. Garcia
Carbohydrate polymers 2016 v.140 no. pp. 233-237
aqueous solutions, composite polymers, corn starch, gels, microwave radiation, nitrogen, pH, polyglutamic acid, rheology, starch, temperature, viscoelasticity, waxy corn
Graft copolymers of waxy maize starch and poly-γ-glutamic acid (PGA) were produced in an aqueous solution using microwave irradiation. The microwave reaction conditions were optimized with regard to temperature and pH. The temperature of 180°C and pH7.0 were the best reaction conditions resulting in a PGA graft of 0.45% based on nitrogen analysis. The average graft content and graft efficiency for the starch–PGA graft copolymer prepared at 180°C and pH7.0 were 4.20% and 2.73%, respectively. The starch–PGA graft copolymer produced at 180°C and pH7.0 could absorb more than 20 times its own weight amount of water and form a gel. The preliminary rheology study revealed that the starch–PGA graft copolymer gel exhibited viscoelastic solid behavior while the control sample of waxy starch showed viscoelastic liquid behavior.