Study Of Salt-Resistance Superabsorbent Polymer

Superabsorbent polymer is a new type of functional polymer material, it is widely used in agriculture, industry, building industry, and other fields because of its excellent water absorption and water retention. Superabsorbent polymer presents network structure from microscopic perspective, there are a large number of hydrophilic functional groups connected to the network such as -COOH,-SO₃H,-OH, and other functional groups. Traditional superabsorbent polymer with poor salt-resistance is limited in applications, superabsorbent terpolymer based on acrylic acid, acrylamide and 2-acrylamido-2-methylp- ropane as monomers, ammonium persulfate-sodium sulfite as initiator, N,N'-methylene bis-acrylamide as crosslinking agent is prepared via aqueous solution polymerization. In order to improve absorption capacity, diatomite,bentonite and other inorganic materials are introduced, salt-resistance superabsorbent polymer are obtained.It obtains the best reaction conditions through single-factor experiments and orthogo- nal experiments that the mole ratio of AMPS:AM:AA is nearly 0.5:4:3, the temperature is nearly 60℃, reaction time is nearly 5 hours, the content of crosslinking agent is nearly 0.01%, the content of initiator is nearly 0.125% and monomer concentration is nearly 30%. Absorption capacity of synthetic superabsorbent polymer in above conditions is 1350g/g and 115g/g in adequate distilled water and 0.9%NaCl solution respectively. The presence of hydrophilic functional groups is confirmed through FTIR spectra, particle size distribution and microstructure of productions are observed through SEM. Experiments show that pH of absorption circumstance and water consumption seriously effect absorption capacity, when pH is between 3 to 10, superabsorbent polymer has high absorption capacity, the more water consumed, the higher absorption capacity is.Compound superabsorbent with diatomite or bentonite has better hydrophilicity than superabsorbent terpolymer because of a large number of–OH in diatomite and bentonite. Within 30 minutes, in 200mL distilled water, absorption capacity of superabsorbent terpolymer is 1050g/g, absorption capacity of diatomite superabsorbent polymer is 1200g/g, absorption capacity of bentonite superabsorbent polymer is 1150g/g; in 0.9% NaCl solution, absorption capacity is 110g/g, 115g/g, 115g/g respectively. It shows that compound superabsorbent polymer has better absorption capacity.