Its Straw-based High-performance Synthetic Absorbent Resin Irradiation

In this paper, the pulverized wheat straw was chosed as raw material. A super-absorbent polymer has been synthesized by gama ray from cobalt60with chemically modified pulverized wheat straw and acrylic acid (AA) in aqueous solution, at room temperature and normal atmospheric pressure. The influence factors, such as the size of straw particle, concentration of sodium hydroxide solution, treatment time of sodium hydroxide solution, radiation dose, neutralization degree of AA, weight ratio of AA to wheat straw, different origin of straw were investigated. Moreover, the optimized conditions of irradiation polymerization process were determined by single factor and orthogonal experiments, the super-absorbent polymer sample was prepared with the optimized conditions, and the swelling properties and IR spectrum of the prepared super-absorbent polymer were investigated. Finally, the absorbency mechanism of the super-absorbent polymer was discussed. The main findings were as follows:1. The optimum conditions of SAP prepared with wheat straw by gama irradiationThe appropriate treatment of wheat straw before polymerization can increase the reaction rate and improve the performance of the superabsorbent properties. The origin of wheat straw was no significantly affected with the absorbency of the final SAP products.The super-absorbent polymer composed of poly (acrylic acid) and wheat straw was prepared by using gama irradiation, at room temperature and normal atmospheric pressure. The prepared super-absorbent polymer has good absorbency, high gel strength and fine water-retaining properties.Through the single factor and orthogonal experiments, the optimum conditions was determined as follows:the size of straw powder was25to100mesh, the concentration of sodium hydroxide solution was20%to25%, the time of pretreatment straw powder was12to24h, the weight ratio of AA to wheat straw was8:1to10:1, the neutralization degree of AA was70%to80%and the irradiation dose was8to10kGy.2. The absorption performance test of SAP prepared with wheat straw by gama irradiationThe super-absorbent polymer was prepared with optimum conditions, with the absorbencies of662g/g in distilled water,85g/g in0.9wt%NaCl solution,645g/g in1 wt%urea solution,326g/g in tap water,299g/g in natural pond water,66g/g in inhalation urine. The absorption rate in distilled water and saline could be reached saturation in10min.The absorbency of the super-absorbent polymer was declined rapidly at first, and then slowed down in NaCl solution. It still maintained a high absorbency in the higher concentration of NaCl solution. The absorbency of the super-absorbent polymer was maintained the best level about600g/g or more in water with pH between4to10. When the PH<4and pH>10in water, the absorbency of SAP was declined rapidly. The absorbency of the super-absorbent polymer was maintained the best level about600g/g or more in distilled water with temperature between4to60℃and had good thermo-stability. The water retention properties of the super-absorbent polymer were good both in high temperature and high pressure in distilled water.3. The analysis of structure and absorption mechanism of SAP prepared with wheat straw by gama irradiationThe super-absorbent had been proved with straw cellulose and acrylic acid via IR spectrum analysis. According to the conductivity during the suction and infrared spectroscopy results, the absorption mechanism and properties of straw-based SAP were determined by the chemical molecular structure and space of the physical structure of the SAP.