Synthesis And Properties Of Polymer/Bentonite Super Absorbent Composite

The superabsorbent resin is a kind of functional macromolecule material which has received more and more attention. Its application in the field of agriculture as water-rentention reagent and slow-release fertilizer is very important to the development of national economy. On the basis of reviewing the synthesis and application in agriculture of organic-inorganic superabsorbent composites, series of organic-inorganic superabsorbent composites were synthesized, as well as their capacities were studied.In order to reduce the cost of production and improve the hydrogel strength and salt resistance, diallyldimethylammonium chloride (DADAAC) or poly (diallyldimethylammonium chloride) (PDADAAC) was used to organify bentonie followed by copolymerizing with acrylic acid (AA) or interpenetrating with poly(acrylic acid) (PAA) to prepare amphoteric superabsorbent composites. The influences including the type of bentonite, dose of crosslinker and initiator, polymerization temperature, dose of AA, DMDAAC or PDMDAAC and water on the swelling capacity of amphoteric superabsorbent composites were investigated in detail. Under the optimum condition, the two have the swelling capacity of 1964g/g and 1578 g/g in deionized water, 139 g/g and 136 g/g in 0.9% NaCl solution, respectively. The swelling kinetics, swelling capacity in different concentration of NaCl solutions and different pH solution, water retention capacity and swelling reversibility were investigated. Besides, we have attempted to apply them to for slow-release fertilizer of KH2PO4.Amphoteric superabsorbent composites of poly (acrylic acid-co- dimethyldiallylammonium chloride)/cationic starch/Ca-bentonite were prepared by static aqueous polymerization using cationic starch as stabilizer for bentonite due to its high viscidity and absorbing capability. Meanwhile, the biodegradability and the compatibility with environment were impoved. The influences including polymerization temperature, dose of water, degree of substitution of cationic starch, dose of AA on the swelling capacity of superabsorbent composites were investigated in detail. The swelling behaviors were discussed. Under the optimum condition, the product showed the swelling capacity of 1288 g/g and 96 g/g in deionized water and 0.9% NaCl solution, respectively. The product has excellent property of hydrogel strength and swelling reversibility.