Synthesis And Charcterization Of Kaolin/Acrylic Salts Composite Superabsorbent Resin

Superabsorbents are loosely crosslinked hydrophilic polymers, which could absorb plenty of water in a relatively short period of time and have a better water-retention capacity under pressure. Because of their excellent features, superabsorbents are widely used in indusity, agriculture, horticulture and medicine for drug delivery and so on. A novel kaolin composite superabsorbent was prepared by water solution polymerization, its performance and influencing factors, structural characterization was also analyzed in this paper.In the study of kaolin/ poly(potassium acrylate) composite superabsorbent, using partially neutralized acrylic acid and kaolin as raw material, potassium persulfate as initiator, N,N-methylene-bis-acrylamide as crosslinking agent, this novel kaolin composite superabsorbent was prepared by water solution polymerization. The effects of amounts of neutralization degree of acrylic acid, kaolin, crosslinking agent, initiator and monomer concentration on composite superabsorbent were studied. The results showed that the high-performance composite superabsorbent could be obtained as neutralization degree of acrylic acid was 80%, weight fraction of initiator, crosslinking agent, monomer concentration was 0.25%, 0.015%, 35% respectively. The water-absorbency of the product in distilled water and saline water could be 728g/g and 70.2 g/g separately.In the experiment of kaolin/ poly(potassium acrylate-acrylamide) composite superabsorbent, using partially neutralized acrylic acid and kaolin as raw materials, potassium hydroxide as initiator, N,N-methylene-bis-acrylamide as crosslinking agent, The results showed that the high-performance composite superabsorbent could be obtained when neutralization degree of acrylic acid was 80%, weight fraction of acryamide, initiator, crosslinkingagent, monomer concentration was 6%, 0.28%, 0.015%, 35% respectively. The water-absorbency of the product in distilled water and saline water could be 919g/g and 92 g/g separately.In the test of kaolin/strach-grafting-poly(potassium acrylate) composite superabent, compared with corn starch, cassava starch, murphy starch, pachyrhizus starch crossing gafted potassium acrylate respectively, the results indicated that corn starch was the best choice. Therefore, with corn starch, partially neutralized acrylic acid and kaolin as raw material, potassium persulfate as initiator, N,N-methylene-bis -acrylamide as crosslinking agent, kaolin/strach-grafting-poly(potassium acrylate) composite superabent was prepared by water solution polymerization. The results showed:when neutralization degree of acrylic acid was 80%, wt(starch) was 10%, wt(initiator) was 0.25%, wt(crosslinking agent) was 0.013% , wt(monomer concentration) was 35%, the high-performance composite superabsorbent could be obtained. The water-absorbency of the product in distilled water and saline water could be 654g/g and 66g/g respectively.The kaolin/poly(potassium acrylate) composite superabsorbent was characterized by infrared spectroscopy(IR), X-ray diffraction(XRD), scanning electron microscopy (SEM), thermogravimetry (TG). There was no obvious change in the structure of kaolin and it was dispersed homogeneously as tiny particles in polymer, In the complexing process of kaolin and organic monomer, surface grafting polymerization took place in the polymer network. It was found that its thermal stability of superabsorbent composites was significantly enhanced by adding kaolin power.By adding composite water-absorbent resin to the soil in the experiment,the results showed it could effectively enhance the capacity of water-absorption and water-retention, improve the inhibition of evaporation capacity and volume swelling. But the growth of crops would not be affected.