Swelling Behavior of Guar Gum-g-Poly(Sodium Acrylate -co-Styrene)/Attapulgite Superabsorbent Composites
(1847-1863) Journal of Macromolecular Science, Part B - Physics 50  #10 (2011)
Shi, Wang and Wang, of the Graduate University of the Chinese Academy of Sciences, China, prepared a series of superabsorbent composites, guar gum-g-poly(sodium acrylate-co- styrene)/attapulgite [GG-g-P(NaA-co-St)/APT] by simultaneous grafting partially neutralized acrylic acid and hydrophobic styrene (St) onto guar gum in the presence of attapulgite as an inorganic component.  Equilibrium swelling capacity strongly depended on the concentration of St, drastically increasing with increasing St concentration to 24.3 mmol/L and then decreasing. The influence of St concentration on the swelling kinetics of the superabsorbent was studied by means of a Schott's second-order model.  Results showed that the concentration of St is the key factor influencing equilibrium swelling capacity of the superabsorbent composites in each swelling media, and moderate amounts of St could enhance the responsiveness of the corresponding superabsorbent composite to external stimulation.  (RDC 8/22/2011)

( 1653-1661) Polymer Degradation and Stability 96 #9 (2011)
Phang et al ofJalan Universiti,, Malaysia, prepared an alginate-based superabsorbent polymer (SAP), alginate-graft-poly[acrylamide-co-(itaconic acid)-g-(acrylic acid)] or Alg-g-P(AM-co-IA-g-AA) to examine its thermal and microbial degradation properties through Thermogravimetric Analysis (TGA), and soil supernatant test (with and without added nutrient) and soil burial test, respectively.  The TGA thermogram of the SAP showed three degradation steps.  The first degradation step was due to the thermal degradation of alginate and decomposition of the functional groups of PAM, PIA and PAA; whereas the second degradation step occurred as a result of the decomposition of PAM, PAA and PIA chains.  Further decomposition of PIA contributed to the third degradation step. Among all the soil samples [tropical forest soil (TF), former tin mine lake soil (TM), peanut farm soil (PF), indigenous microorganism soil from an organic vegetable farm (OF), and oil palm plantation soil (OP)] tested, OF soil degraded the polymer sample most effectively, with the highest weight loss of 82.6% (with added nutrient) and 82.8% (without added nutrient) in soil supernatant tests, and 63.5% in soil burial test.  (RDC 7/29/2011)

Swelling study of superabsorbent PAA-co-PAM/clay nanohydrogel
(1533–1538)Journal of Applied Polymer  Science 120 #3 (2011)
Patra and Swain of North Orissa University, India prepared a series of superabsorbent composites were prepared from acrylic acid (AA), acrylamide (AM), and Cloisite® 30B by aqueous solution polymerization technique using ammonium peroxodisulfate (APS) as initiator.  It was found that the nanohydrogel acquired highest water absorbency with 2% clay loading. The reswelling ability and water retention capacity of the PAA-co-PAM hydrogel and PAA-co-PAM/clay nanohydrogel were also measured. The water absorbency was found to increase after each reswelling for which it may be useful as recyclable superabsorbent material.  (RDC 2/16/2011)

Synthesis and swelling characteristics of a pH-responsive guar gum-g-poly(sodium acrylate)/medicinal stone superabsorbent composite
(210–218)Polymer Composites 32 #2 (2011)
Zhai, Wang and Wang of the Graduate University of the Chinese Academy of Sciences, China have synthesizeda series of pH-responsive superabsorbent composites were synthesized by the free-radical grafting copolymerization of natural guar gum (GG), partially neutralized acrylic acid (NaA), and medicinal stone (MS) using ammonium persulfate (APS) as the initiator and N,N′-methylene-bis-acrylamide (MBA) as the crosslinker.  Results indicated that NaA had been grafted onto GG macromolecular chains and MS participated in the polymerization reaction. The incorporation of MS obviously improved the surface structure, thermal stability, water absorption capacity, and rate. Multivalent saline, cationic surfactant, and dye showed more remarkable effects on the water absorption than did monovalent or anionic ones. The composites showed excellent responsive properties and reversible On–Off switching characteristics.  (RDC 1/28/2011)