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Preparation of starch–poly–glutamic acid graft copolymers by microwave irradiation and the characterization of their properties
- Xu, Jingyuan, Krietemeyer, Elizabeth F., Finkenstadt, Victoria L., Solaiman, Daniel, Ashby, Richard D., Garcia, Rafael A.
- Carbohydrate polymers 2016 v.140 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.