Synthesis Of Super Absorbent Resin Of Starch Grafting Polyacrylic Acid By Irradiation

Super absorbent resin is a kind of novel polymer material, which has the super-performance of absorbing and retaining water. Many countries have been conducting in its research and development. At present its synthetic technology has such problems as long reaction time, high energy-consuming, and wastewater. In this paper, the irradiation technology was utilized which has many advantages such as high efficiency, without Initiator and pollution in the reaction. And a green novel technology has been developed for synthesizing super absorbent resin, based on the starch graft copolymerization under irradiation.By the research of tapioca starch and acrylic acid graft copolymerization, influencing rules of reaction conditions were discussed. Under the optimal conditions (the proportion of acrylic acid with starch is3.2: 1, radiation dose 1332Gy), water-absorption power of superabsorbent resin is 388g/g, salt-water absorption power is 53g/g. IRspectrum of resin and SEM photograph of resin shows that acrylic acid has been grafted to starch. The graft percentage of optimal conditions is83.98%. The molecular weight is 1.11 105.In order to improve water absorbency, NaOH was added into reacting matter. Starch grafted sodium polyacrylate was make. Effects of Monomer concentration, neutralization degree and irradiation dose on water absorbency were discussed. By orthogonal experiment, optimizing condition was gotten. Under the optimizing condition (the proportion of acrylic acid with starch is 2.6: 1, neutralization degree of acrylic acid is 80%, radiation dose 4.1kGy), water absorbency and water retention performance of super absorbent resin is excellent, water-absorption power of super absorbent resin is 1357g/g, salt-water absorption power is 153g/g. IR spectrum of resin proves that sodium acrylate has been grafted to starch.Water absorbing mechanism of resin has been discussed. The essence of water absorbing is explained from the thermodynamics. Some phenomena in experiments are explained by Flory equation. It can be the reference for further setting the mathematic model of water absorbing.