| A novel SA/P(AA/AM) interpenetrating polymer network super absorbent resin were synthesized via fractional steps method. First step, preparation of acrylic acid (AA)-graft-starch copolymer, which is using cassava starch(St) and acrylic acid(AA) as polymerization material, ammonium persulfate and sodium hydrogensulfite (NH4)2S2O8-NaHSO3 as the redox initiator. Second step, preparation of SA/P(AA/AM) interpenetrating network super absorbent resin, which is using acrylic acid(AA) and acrylamide(AM) as polymerization monomer, N,N'-methylene biasacrylamide as polymer crosslinking agent, ammonium persulfate and sodium hydrogensulfite as the redox initiator. And the structure and properties were characterized and researched.1.Synthesis of SA/P(AA/AM) super absorbent resin with interpenetrating networkStudy polymerization conditions of SA/P(AA/AM) by ways of signal fator experiments and optimized by orthogonal experiment. The orthogonal experiment results showed the optimal reaction conditions were as follow:monomer A A/AM proportion 0.4, initiator 0.32%, crosslinking agent 0.035%, neutralization degree 85%, SA 8% and the reaction temperature was 55℃. Under such condition, the water absorbency and saline absorbency of SA/P(AA/AM) resin can reach 1480g/g and 120g/g respectively.2. Study on mechanisms of absorbing water for super absorbent resinAppling Flory thermodynamics to mechanisms of water absorption of super absorbent resin, we can conclude that structure of super absorbent resin must have two conditions:have a large number of hydrophilic group and structure of cross linked network. The more concentration of dissolving ions, the more water absorbency of the resin. The more cross-linked density the lower water absorbency the resin. Well-distributed cross-linked network is the fundamental element to increase absorbing water power. The water absorption power is the result of extention of macromolecular chains generated by repulsion of macromolecular electrolyte and of resistance of macromolecular chains extending generated by cross-linked network and hydrogen bond.3. Study on structure and properties of SA/P(AA/AM) interpenetrating network super-absorbent resinThe water retention in high temperature and in high-speed centrifugation conditions for the products have been studied. And, the experiment results indicated that:after dry 14h in 70℃SA/P(AA/AM) resin water retention is 59.5%; after centrifugal separation in 5000r/min centrifugal machine the water retention is 54.6%.The water absorbability of the SA/P(AA/AM) resin under different temperature and repeating absorbability were researched. The experiment results indicated that the effect of temperature on absorbability was mild. Besides,repeating absorbability of SA/P(AA/AM) resin was good.The result of IR,TGA,SEM. TEM and X-ray of SA/P(AA/AM) shows that the starch polysaccharide macromolecular skeleton of SA and the branch chain of grafting polyacrylic acid (PAA) thrust deep into the cross-linked network of P (AA/AM),which can reinforce the molecular interaction between them. The thermo-decomposing temperature and thermal stability were enhanced effectively for physical winding between the macromolecular chain of SA and P(AA/AM) and plenty of the hydrogen bonding. 4. Study on the enlargement test of the synthesis of super absorbent resinOn the basis of laboratory experiment, the enlargement test research has been proceeded successfully for super absorbent resin of the acrylic acid grafted starch/ crosslinking acrylamide copolymer IPN. The result shows that the synthesis technology of it is reasonable, the technology parameter is stable and the conversion ratio of monomer is high. The conversion ratio of monomer in the pilot-plant test reaches to 98% and the cost is low. The characters of the resin have surpassed that of the same kind of resin abroad. The expected design goal is obtained. All that provide a strong technology foundation for the pilot-plant test production. |
PDF Full Text Request