Preparation And Properties Of Modified Polyaspartic Acid Ternary Composite Water Absorbent Resins

The water absorbent resin is a kind of water superabsorbent that can absorb large amounts of water,because of its dvantages of excellent water absorption and water retention so that it can be applied to a number of areas.Based on the green concept,aspartic acid as one of the green raw materials was used to synthesize absorbent resin,however,polyaspartic acid absorbent resin has a single structure,high cost and poor salt tolerance.The water-absorbent resin is prepared by using a variety of components,which can improve comprehensive performance of the resin.Therefore,biodegradable and biocompatible composite water absorbent resins of modified polyaspartic acid/polyacrylic acid/organic montmorillonite?KPAsp/PAA/OMMT?and modified polyaspartic acid/polyacrylic acid/carboxymethyl cellulose?KPAsp/PAA/CMC?were prepared by aqueous solution polymerization with modified polysuccinimide,acrylic acid,organic montmorillonite and carboxymethyl cellulose as raw materials.In this paper,the two kinds of composite resins' s synthesis parameters,absorption kinetics,pH sensitivity,temperature sensitivity,salt sensitivity and liquid absorption in artificial blood,artificial urine and ethanol were studied.The structure,thermal stability and surface morphology of the composite resins were characterized.The contents and results are as follows:?1?modified polysuccinimide?KPSI?,acrylic acid?AA?and organic montmorillonite?OMMT?were used as raw materials,potassium persulfate?K2S2O8?as initiator,N'N-methylene bisacrylamide?MBA?as cross-linking agent,KPAsp/PAA/OMMT composite water absorbent resin was prepared in water soluble systems.The effect of synthesis parameters on the absorption rate of composite resin was discussed,the resultsshowed that when the composition ratio of each component is m?KPSI?: m?AA?= 1: 3,the mass of organic montmorillonite is 10wt% of the mass of KPSI,the particle size of montmorillonite is 230 300 mesh through mesh screen,acrylic acid is neutralized 70%,the amount of initiator and crosslinking agent is 0.5wt% and 0.2wt% of monomer,the reaction rate was 70 ? and the reaction time was t = 3 h,the absorption rate of the composite resin was the best,and the absorption rate in the deionized water and physiological saline was 675 g/g and 118 g/g,respectively.?2?The structure,thermal stability and surface morphology of KPAsp/PAA/OMMT composite water absorbent resin were characterized by FTIR,XRD,TGA and SEM.The results showed that the crosslinking reaction occurred between the layers of montmorillonite and the montmorillonite was completely stripped to reach the nanoscale dispersion.The thermal stability of the composite resin was improved,and the composite resin had a uniform and regular pore structure.The kinetic analysis of the absorption of the composite resin showed that the liquid absorption kinetics belonged to the Fick diffusion.?3?KPAsp/PAA/OMMT composite absorbent resin exhibited good sensitivity of pH,temperature and salt.The absorption rate of the composite resin showed two peaks at pH = 6and pH = 10,the low critical temperature dissolution temperature?LCST?was 50 ? at which the composite resin exhibited the optimum liquid absorption rate.The absorption rate in NaCl,CaCl₂ and FeCl₃ solution decreased with the increase of salt concentration,and the ability to absorb liquid in the same concentration of different salt solution is NaCl> FeCl₃> CaCl₂.The absorption rate of the composite resin in artificial urine,artificial blood and ethanol aqueous solution were investigated,the results showed that the maximum absorption rate of composite resin in artificial blood,artificial urine and 50% ethanol aqueous solution were 110 g/g,46 g/ g and 215 g/g,which was 3.3 times,1.8 times and 1.6 times that of KPAsp,respectively.?4?KPAsp/PAA/CMC composite water absorbent resin was prepared under the action of initiator and crosslinker by aqueous solution polymerization.The effect of synthesis parameters on the absorption rate of composite resin was discussed.When the composition of raw material was m?KPSI?/ m?AA?/ m?CMC?= 1: 3: 0.15,the crosslinking agent and initiator were 0.1% and 0.5% by weight,the neutralization degree of acrylic acid was 70%,themass concentration of acrylic acid was 12.5%,the reaction temperature was 70 ? and the reaction time was 3 hours,The synthetic resin had the best water absorption rate in deionized water and physiological saline,which is 845 g/g and 130 g/g,respectively.?5?The KPAsp/PAA/CMC composite water absorbent resin was characterized by FTIR,TGA and SEM.The results showed that the composite composite resin is successfully prepared,the thermal stability and the pore structure was improved.The liquid absorption kineticsof the composite resin showed that the swelling of the composite resin belonged to the Fick diffusion.?6?The sensitivity of KPAsp/PAA/CMC composite water absorbent resin was investigated.The peak of the absorption rate of the composite resin in pH = 5 and pH = 9showed a good pH sensitivity.The absorption rate of the composite resin reached a maximum at 55 ??low critical solution temperature?.The absorption rate of the composite resin gradually decreased with the increase of the salt solution concentration in the same salt solution,and the liquid absorbing ability of the resin in the different salt solution with same concentration was NaCl> FeCl₃> CaCl₂.The composite absorbent resin had good liquid absorption performances in artificial blood and artificial urine,the absorption rate was 211 g /g and 142 g/g,respectively,which was 6.39 times and 5.68 times of that of KPAsp.In 50%ethanol aqueous solution,the resin absorption rate of the composite resin was 295 g/g,which was 2.2 times that of KPAsp.