Rate of swelling of sodium polyacrylate

Abstract

SYNOPSISThe kinetics of the swelling of sodium polyacrylate (NaPA) , a hydrophilic polymer, was studied gravimetrically, by microscopic observation, and calorimetrically. The swelling process followed first-order kinetics and the rate constant was of the order of s-'. The gravimetric method, however, was not useful for kinetic studies. The rate constant was depressed by the addition of sodium chloride. The activation energy of the swelling was 46.0 f 6.2 (kJ mol-') and decreased with the increase in sodium chloride concentration. In acid solution, the activation energy was almost the same as that in water. The heat of the swelling was 196 ? 17 J g-' and did not vary with the addition of sodium chloride.

Preparation, swelling behaviors and application of polyacrylamide/attapulgite superabsorbent composites

“…Ogawa et al have already investigated the swelling kinetics of poly(sodium acrylate) by picture analysis with a microscope-VTR (video tape recorder) system, calorimetry and gravimetry techniques. 6 Superabsorbents are used widely in many fields, such as feminine napkins, disposable diapers, agriculture, etc., [7][8][9][10][11] where water absorbency in saline solutions and water retention ability of superabsorbents is critically important. Therefore, it is essential and practical to investigate swelling properties of superabsorbents in various saline solutions and their water retention ability.…”

Superabsorbent polymeric materials. II. Swelling behavior of crosslinked poly[sodium acrylate-co-3-dimethyl(methacryloyloxyethyl) ammonium propane sulfonate] in aqueous salt solution

“…26 SA monomer was prepared as previously reIn our previous report, 27 the swelling behavior ported. 27 of a series of crosslinked poly(sodium acrylate-cohydroxyethyl methacrylate), [poly(SA-HEMA)] absorbents was presented.…”

Superabsorbent polymeric materials VII: Swelling behavior of crosslinked poly[sodium acrylate-CO-trimethyl methacrylamido-propyl ammonium iodide] in aqueous salt solutions

“…9 -23 Flory 24 explained the swelling mechanism for hydrophilic polymers as being with a nonionic network or ionic network structure. Ogawa et al 25 studied the kinetics of the swelling of poly-(sodium acrylate)[poly(SA)] by picture analysis with a microscope-VTR system, calorimetry, and gravimetry techniques.…”