Study On The Synthesis And Conductive Hydrogel Of Poly Sodium Acrylate/bentonite Superabsorbent Composites

Superabsorbents are loosely crosslinked hydrophilic polymers, which have the ability to absorb considerable amounts of water or aqueous fluids in relatively short periods of time and retain water under pressure. Because of their excellent characteristics, superabsorbents are widely used in agriculture, horticulture, sealing composite and medicine for drug delivery and so on. The synthesis, structure, conduntive hydrogel of poly sodium acrylate/bentonite superabsorbent composites was investigated in the paper.Using acrylic acid and bentonite as start material, cyclohexane as dispersion medium, N,N'-methylene-bis-acrylamide as crosslinking agent, potassium hydroxide as initiator, Span as suspending agent, a sodium acrylicate-bentonite superabsorbent composite with even size was synthesized by inverse suspension polymerization reaction and aqueous solution polymerization. The influence of synthetic conditions, such as the concentration of crosslinker and initiator, the amount of bentonite and reaction temperature on the water absorbency of the superabsorbent composites was researched, and optimum polymerization conditions were obtained.The water absorbency and salt water absorbency of the superabsorbent composite is 1340 g/g and 92 g/g respectively. The composite has excellent performance of water retaining, which absorbed water over 50% after being dried 10 hours at 110 ℃ in oven, and the absorbed water of 50% in half an hour. Which indicated the better water absorbency, retain water and faster absorption velocity.A novel hydrogel electrolyte with conductivity 500 ms/cm was prepared by immersing poly-sodium acrylate/bentonite superabsorbent into an electrolyte aqueous solution. The hydrogel electrolyte exhibits liquid-like ionic conductivity, and the conductivity of the hydrogel electrolyte mainly depends on the ionic intensity, the pH value and temperature of the solution immersed. The water absorbency of superabsorbent has a great impact on the conductivity of the hydrogel electrolyte. But under a certain extent, the preparation condition of superabsorbent has a small influence on the conductivity of the hydrogel electrolyte.The poly (sodium acrylicate)/bentonite superabsorbent composite is characterized by scanning electron microscopy (SEM), infrared spectra, X-ray diffraction(XRD), thermogravimetry (TGA), differential scanning calorimetry (DSC) analysis. It was found that disperse property and thermal stability of the superabsorbent composites was enhanced by adding bentonite power. It was also confirmed that the bonding water and non-bongding water exist in the gel of superabsorbent composites.The structure of superabsorbent composite is reticulation.