| Superabsorbent resin(SAR)is a functional polymer material with high-performance water absorbent and retention,which are widely used in various fields.However,most of the superabsorbent are high cost,and has low thermal stability and anti-salt performance.The new synthetic methods are attempted to improve the properties of the SAR and to solve those problems.Recently,inorganic composite resin with excellent properties has been extensively studied.Therefore,it is has the important practical significance for preparation and study of the property of water-absorbent composite resin.In this thesis,the organic bentonite was prepared from Na-bentonite through purification and organic modification.Water-absorbent composite resin based on organic bentonite was synthesized via aqueous solution polymerization from the self-produced organic bentonite,itaconic acid(IA)and N-methylol acrylamide(N-MAM)with potassium persulfate-sodium bisulfite as initiator and N,N’-methylenebis-acrylamide(MBA)as crosslinker.The preparation conditions,properties and structure were investigated.The main contents are as follows:(1)The water-absorbent resin based on N-MAM/IA was synthesized via aqueous solution polymerization and the influences of temperature,neutralization degree for IA,the molar ratio of IA to N-MAM,amount of initiator and cross-linking on the water absorbency of the resin based on N-MAM/IA were studied.Based on single factor experiment,the optimized synthetic conditions were obtained.The results show that the temperature was 50 C,the neutralization degree for IA was 85%,the molar ratio of IA to N-MAM was 1:4,the initiator amount and the cross-linking agent amount was 0.4%and 0.08%of total molar equivalents of monomer,respectively.The water absorption ratio was up to 736 g/g in deionized water,and the morphology of the water-absorbent resin was also investigated by SEM.(2)The organic bentonite was synthesized and the influences of temperature,modification time,and amount of CTMAB on the layer microstructure of the bentonite were investigated,and the optimized synthetic conditions were obtained.The results showed that the modification temperature was 60℃,the modification time was 3 h,the amount of CTMAB was 30%of the mass of Na-bentonite,the diffraction angle and the layer spacing of the organic bentonite was 3.8 and 2.32 nm,respectively.The sample was characterized by FTIR and XRD.The results proved that the modifier was successfully inserted crystal layer of bentonite.(3)Water-absorbent composite resin based on organic bentonite was synthesized via aqueous solution polymerization.The influences of the amount of organic bentonite and solution pH were investigated,and the optimized amount of organic bentonite was obtained.The results show that the amount of organic bentonite was 3%of the mass of total monomers mass,the water absorption ratio of the composite resin was up to 763 g/g in deionized water and 52 g/g in NaCl solution containing 0.9%of NaCl in mass,the water absorbency and anti-salt performance of the composite resin was higher than the resin based on N-MAM/IA.Water absorbency of the composite resin with low cost and certain alkali resistance was stronger at pH 7-10.TGA analysis indicated that the thermostability of the composite resin was also improved. |
