Study On Polyacrylamide-based Superabsorbent

Using acrylamide(AM), 2-acrylamido-2-methylpropanesulfonic acid(AMPS), maleic anhydride (MA) as monomers, potassium persulfate (PPS) and N,N'-methylene-bis-acrylmide(NMBA) as initiator and crosslinker respectively, the PAMA(i.e. poly(acrylamide-co-2-acrylamido-2-methylpropanesulfonic acid) and PAMM(i.e, poly(acrylamide-co-maleic anhydride) were prepared in aqueous solution.During the experiment of preparing PAMA, after the method of temperature-rising had been decided, the optimum polymerization condition was obtained by combining orthogonal design and single-factor-study: n(AMPS):n(AM)=l:l, the mass percent of total monomers [M]=20%, of initiator [I]=0.02%, of crosslinker [C]=0.01%, and the degree of neutralization of AMPS N=65%, reaction temperature 60℃(4h)→80℃(3h), reaction time 7h. The absorbencies of the PAMA, which are synthesized under the above conditions, in distilled water and in 0.9wt%NaCl aqueous solution are up to 2215g/g and 119g/g, respectively.The effects of various salt solutions and the pH values of solutions on the swelling properties were studied systematically, and the swelling behaviors of the PAMA in these salt solutions were explained.The absorbencies of the PAMA in artificial urine, in artificial blood, in water at different temperature, and in different organic solvents were measured.The swelling behaviors of the PAMA in the mixtures of some water/organic solvent were also investigated, and were explained.In addition, the swelling rates of the PAMA in distilled water and in 0.9wt%NaCl aqueous solution, the water retention of water-saturated gel at constant temperature, and the water retention in sand at high temperature were also measured.During the experiment of preparing PAMM, after deciding the method of the temperature-rising, the relatively optimum polymerization conditions was obtained by combining orthogonal design and single-factor-study: n(AM):n(MA)=5:l, the mass percent of total monomers [M]=25%, of initiator [I]=0.4%, of crosslinker [C]=0.02%, and the degree of neutralization of MA N=130%, reaction temperature 30℃(4h)→60℃(4h)→80℃(3h), reaction time 11 h. The absorbencies of the PAMM, which are synthesized under the above conditions, in distilled water and in 0.9wt%NaCl aqueous solution are up to 3193g/g and 213g/g, respectively.The swelling rates of the PAMM in distilled water and in 0.9wt%NaCl aqueous solution were measured.