Synthesis And Property Of Superabsorbent Polymers Modified By Calcium Carbonate

At present, it has always been a hot spot in the field of polymer chemistry research thatstudying on the synthesis method and the comprehensive performance of the superabsorbentpolymers. Besides the characteristics of the common polymer materials, high absorbent resinalso has excellent properties for absorbing water and holding water, the good biodegradationproperties, the good capacity of adsorbing transition metal ions in solution, and the extremestability to the acid, alkali, light and heat and so on.In this paper，the composite modified resins were prepared by aqueous solutionpolymerization with more than20different kinds of inorganic substances such as the calciumcarbonate, the sodium thiosulfate, the sodium silicate, the aluminum chloride as additives. Itis determined that the liquid absorbent performance and the adsorption-desorptionperformance for copper ions of these composite modified resins. The results showed that notonly the liquid absorbent performance but the adsorption-desorption performance for copperions of composite modified resin using calcium carbonate as the additive is best which isprepared with the calcium carbonate as the additive.Some control-factors are investigated separately through orthogonal experiment to studytheir impact on the liquid absorbent and the adsorption performance of the modified absorbentresin which is prepared with the calcium carbonate as the additive. It is worked out that themajor-minor order of the factors which influence the liquid absorbent of modified absorbentresin. It is cross-linking agent> additive dosage> initiator dosage> neutralization degree>temperature> monomer concentration; The major-minor order of the factors which influencethe adsorption performance of modified absorbent resin is neutralization degree>cross-linking agent dosage> temperature> initiator dosage> additive dosage> monomerconcentration.Single factor experiment were used to establish the optimum parameters related to theproduct preparation. The best process conditions were obtained separately about the liquidabsorbent and the adsorption properties for heavy metal copper ions of the modified resinwhich is prepared with the calcium carbonate as the additive. Using15ml acrylic acid as abenchmark, the result show the optimum process conditions: the reaction temperature is55℃,the mass fraction of monomer is20%, the neutralization degree is45%, the modified additivedosage is1g, the dosage of cross-linking agent is1.0%, and the initiator dosage is2.0%respectively, the rate of liquid absorption of modified resin in the distilled water is676.54g/gat room temperature; Using150ml acrylic acid as a benchmark, the result show the optimumprocess conditions: the reaction temperature is55℃, the mass fraction of monomer is20%,the neutralization degree is75%, the modified additive dosage is8g, the dosage of cross-linking agent is1.0%, and the initiator dosage is2.0%respectively, the adsorptionproperties of modified resin for heavy metal copper ions in the0.05mol/L copper sulfatesolution is213.7mg/g at room temperature.After testing the liquid absorbent performance of the high absorbent resin which ismodified by the calcium carbonate for a nine-day at ordinary temperatures and pressures, it isfound that the rate of liquid absorption and the solution preserving of the experimental samplereduce sequentially in the distilled water, tap water and the0.5%NaCl salt solution with theconcentration of salt increasing. The performance of the solution preserving is good in the allsolutions. Compared with the measurement results of the water absorbency and the adsorptionquantity of copper ions of the high absorbent resin at home and abroad, it is found that thewater absorbency of the experimental sample is the highest, the adsorption quantity of copperions is the most one. That is to say the liquid absorbent and the adsorption performance ofabsorbent resin modified by calcium carbonate strengthened obviously.It is characterized by FT-IR that the structure of the high absorbent resin which ismodified by the calcium carbonate. The result shows that the characteristics structure of superabsorbent polymers are found in the sample, such as the groups of—OH、—COOH、—COO—and so on. There is a peak of CO32-out-plane flexural vibration of the calcium carbonateat the point of852cm-1. The peak is very weak and sharp.That is to say the calcium carbonategrafts on the surface of SAP.