Synthesis And Capacity Of Super Absorbent Polymer Of Starch Compositing AA And AM

Super absorbent polymer(SAP), as a new kind of high molecular polymer, which possess the strong ability of water absorbency and water retention has a broad application field.The SAP was synthesized, by Starch, acrylic acid and acrylic amide as raw meterrial, potassium persulfate as initiator, N,N’-methylene bisacrylamide as cross-linking agent. The effects on the water absorption capacity were discussed on multiple factors, the synthetic method was improved, the starch was mixed with monomers without pre-gelatinization dispose, the synthetic process didn’t use nitrogenr to protect, so process of the synthesis was simplfied, manufacturing cost was reduced; the polymerization temperature was75℃, the rate of polymerization was fast, the polymerization reaction finished in about30min, the water absorption capacity rate was enormous, the yield of product was89.5%in this method.The effects on the water absorption capacity of each raw material were discussed under the conclusion of synthesis method, the optimal material ratio was get by single factor experiments and orthogonal experiments. When starch0.5g, acrylic acid5g, potassium persulfate0.01g, N,N’-methylene bisacrylamide0.001g, the neutralization degree of AA75%, the water absorbency of all products were in high level, when molar ratio of acrylamide to acrylic acid was1.5:1, the deionized water absorbency was1013.1g/g, the saline absorbency was89.3g/g. The purification technique was improved in the paper, the purification time reduced to3-4h from8-48h by soaking the crude product for15min in deionized water, the residuary monomer content and pH of SAP were reduced to the specified level, the purification efficient was enhanced obviously.The products were analyzed on water retention and reuse and water absorption speed, the result showed that the comprehensive abilities were better when starch0.5g, acrylic acid5g, molar ratio of acrylamide to acrylic acid2:1, potassium persulfate0.01g, N,N’-methylene bisacrylamide 0.001g, the neutralization degree of AA was75%, the deionized water absorbency was908.1g/g, the saline absorbency was85g/g, the water retention rate of SAP in the air and sandy soil were each70%and71%after16d at home temperature, the water retention rate reduced to71%in12h at860Pa and the water absorbption capacity changed to511.1g/g after6times of desiccation. The relationship between absorption time and absorption amount was analyzied, the fitting result showed that the relationship was y=817.92-840.83exp(-x/4.88), y was for absorption amount (g/g), x was for absorption time (min), the water absorption behavior fitted first order kinetics.