Study On Synthesis And Modifacation Application Of Starch Superabsorbent Resin

Starch superabsorbent resins have many advantages such as available raw materials, lower production cost, good environment compatibility, convenient usefulness, etc. Thus, they are widely applied in numerous fields. However, their applications in some important fields are seriously restricted because of bad anti-degradation ability and reusing property.According to the principle of the free radicals graft copolymerization, superabsorbent resins were prepared by graft copolymerizing between starch and partly neutralized acrylic acid. The technical conditions of the synthesizing process were systematically studied by experiments, which included starches selection, ratio of starch and acrylic acid, neutralized degree of acrylic acid, dosage of initiator, reacting time and temperature, and drying temperature. The optimum technical conditions were determined. By characterizing the basic structure of the product with IR spectrum, the reaction process was confirmed. In order to improve application properties of the product , the blending tests of the superabsorbent with polymers were performed. And the application properties of the blended products were contrastively studied. It was found by sieving experiments with four general starches that the corn starch had the best property for the modifying. The grafting ability of partly neutralized acrylic acid was better than that of acrylic acid. According to the result of orthogonal test, the influent factors on the water sorption of the copolymer in strength turn were the ratio of starch to acrylic acid, the reacting time, temperature, the dosage of initiator and the neutralization degree of acrylic acid. The graft copolymer had the highest water sorption at following conditions: the ratio of starch to acrylic acid was 1:6, the ratio of initiator to raw materials was 0.015:1, reacting time was 2.5h, temperature was 50℃ and neutralization degree of acrylic acid was 92%. The water sorption of the product in water was up to 560 times of itself weight. And water retention of the product had still 100 times after 30 days in soil. By contrasting analysis to the IR spectrum of the starch and graft copolymer, the product shows the IR characteristic peaks of the grafting structure, which proved that the product is the copolymer grafted by starch and acrylic acid.Blending modifications of the graft copolymer with polyvinyl alcohol (PVA) and polystyrene (PS) were respectively studied. The results showed that the anti-degradation ability and re-usability of the blended products were obviously improved. Compared with the graft copolymer, the anti-degradation ability of the product blended with PVA was increased by 84% and the re-usability was increased by 51.4%, and those blended with PS increased by 78% and 35.7%. However, compared to the graft copolymer, the water sorption and retention of the blending products had an acceptable drop.