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Construction and water absorption capacity of a 3D network‐structure starch‐g‐poly(sodium acrylate)/PVP Semi‐Interpenetrating‐Network superabsorbent resin

Huo, Quan, Liu, Dong, Zhao, Jingjing, Li, Jianshu, Chen, Rongna, Liu, Suyan
Die Stärke = 2017 v.69 no.11-12
Fourier transform infrared spectroscopy, X-ray diffraction, absorbents, acrylic acid, adsorption, aqueous solutions, hydrogen, kinetics, neutralization, polymerization, polymers, scanning electron microscopy, sodium chloride, starch, temperature, thermogravimetry, water binding capacity
A new semi‐interpenetrating network superabsorbent resin (semi‐IPN SAR), starch‐g‐poly (sodium acrylate)/PVP, with a three‐dimensional (3D) network structure constructed from a starch‐g‐poly(sodium acrylate) (starch‐g‐PNaA) network and linear poly(vinylpyrrololidone) (PVP) was synthesized by a free‐radical solution polymerization method in the presence of initiator ammonium persulfate (APS) and crosslinker N,N′‐methylene‐bis‐acrylamide (MBA). The synthesis conditions were systematically investigated. The optimum synthesis mass ratio of PVP, starch, APS, and MBA to AA was 20, 30, 1.25, and 0.15%, respectively, the neutralization degree of acrylic acid was 80%, and the reaction temperature was 60°C. Furthermore, the semi‐IPN SAR was characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and three‐dimensional X‐ray diffraction microscopy (3D‐XRDM). FTIR and TGA results agreed that PNaA had been grafted onto the starch macromolecular chains and the starch‐g‐PNaA network was penetrated by linear PVP polymers by a hydrogen binding action. Moreover, the surface morphology of the resin exhibited apparent wrinkling due to the introduction of PVP. The 3D‐XRDM result further proved that the resin was provided with a three‐dimensional network structure. The introduction of PVP and the formation of the semi‐IPN structure greatly enhanced the water absorbency of the resin. The water and saline absorbency of the optimized material was improved to 2017.8 g/g distilled water and 89.7 g/g NaCl aqueous solution (0.9 wt%), respectively. Furthermore, kinetic analysis agreed that the pseudo‐second‐order kinetic model was fitted to describe a whole adsorption process, which indicated the adsorption process was not controlled by diffusion steps.