Synthesis And Property Research Of Amphoteric Super Absorbent Resin Based On Corn Straw

Super absorbent resin is a kind of rapid development and promising new functional absorbent material. It has been widely used in agriculture and forestry, building materials, medicine and health care, desert prevention and daily necessities, etc., because of its good water absorption. In this research, amphoteric super absorbent resins, which used different cationic monomers, were prepared. The factors, which influenced absorbency of super absorbents, were investigated. The molecular structure of the product was confirmed and the performance was analysised. The main conclusions are as follows:Super absorbent resins were synthesized by graft copolyme-rization reaction of acrylic acid and acrylic amide and different cationic monomers onto the pretreatment corn straw by radical polymerization in aqueous solution, using potassium persulfate, cerium ammonium nitrate and sodium sulfite as the initiator and N,N’-methylenebis-acrylamide as crosslinker. The cationic monomers were dimethyl diallyl ammonium chloride, acryloyl-oxyethyl trimethyl ammonium chloride and methacryloxyethyltrimethyl ammonium chloride. The factors, which influenced absorbency of super absorbents, such as weight ratio of monomers and pretreatment corn straw, the amount of initiator and crosslinker, temperature, time and neutralization degree of acrylic acid, were investigated.The experimental results showed that when the mass of the PTCS,AA,AM,DMDAAC were1.0g,5.0g,2.0g,0.5g, respectively; the ratio of K2S2O8to monomer was1,4%;the ratio of MBA to monomer was0.1%; neutralization degree of AA was85%; temperature was60℃and time was4h, the super absorbent resin, which the dimethyl diallyl ammonium chloride was the cationic monomer, reached the best water absorbency of298.78g/g in distilled water and37.04g/g in0.9wt%NaCl solution.When the mass of the PTCS,AA.AM,DAC were1.0g,5.0g,1.0g,0.5g, respectively; the ratio of K2S2O8to monomer was1.2%;the ratio of MBA to monomer was0.1%; neutralization degree of AA was75%;temperature was60℃and time was3h, the super absorbent resin, which the acryloyl-oxyethyl trimethyl ammonium chloride was the cationic monomer, reached the best water absorbency of235.87g/g in distilled water and31.26g/g in0.9wt%NaCl solution.When the mass of the PTCS,AA.AM,DMC were1.0g,5.0g,3.0g,0.5g, respectively; the ratio of K2S2O8to monomer was1.2%;the ratio of MBA to monomer was0.1%; neutralization degree of AA was75%; temperature was60℃and time was3h, the super absorbent resin, which the methacryloxyethyltrimethyl ammonium chloride was the cationic monomer, reached the best water absorbency of198.67g/g in distilled water and26.29g/g in0.9wt%NaCl solution.The molecular structures of the products were confirmed by Fourier transform infrared spectroscopy, the morphological features were evidenced by scanning electron microscopy and the thermal stability was measured by thermogravimetry analysis. The experimental results showed that the super absorbent resins were synthesized successfully by graft copolymerization reaction of monomers onto the cellulose skeleton to form the network structure, which was conducive to the absorption rate. And the thermal stability of the super absorbent resins was good. Through the comparison of three kinds of superabsorbent resins, it was found that the SAR, which used DMDAAC as the cationic monomer, had the best thermal stability. When the tempreture was lower than100℃, the weight loss ratio of this SAR was only6.01%.The network structure of this SAR was the best.The SAR, which used DMC as the cationic monomer, was worst. This was the reason why three kinds of superabsorbent resins had different lluid absorption rate.The effects of pH on the absorbencies, the repetitive absorption of the super absorbent resins and the adsorption of nitrogen and phosphorus on super absorbent resins were researched. The experimental results showed that the super absorbent resins had good water absorbency. when the pi I was in the range of5-9.When the pH was7, SAR had the maximum water absorption capacity.Through repeated using live times, the absorption rate of super absorbent resins was not obviously reduced. The influence of the different cation in the swelling capacity was Na+<K+<Ca2+<Al3 The influence of the different anion in the swelling capacity was NO3-<Cl-<SO42. SAR had good adsorption of ammonium ion and phosphate ion.which could reach equilibrium within4h.