Study On Synthesis And Properties Of AA-Based Superabsorbent With Interpenetrating Network

Super-absorbent polymers are functional materials with certain crosslink degree and network structure, which are widely used in many fields for its excellent absorbency and retention characteristics. Compared with the starch and cellulose superabsorbents, acrylic acid series superabsorbents have advantages of simple preparation technology, excellent comprehensive water absorption, so become the mainstream of superabsorbent resin products, and it's also the researchers focus. The traditional absorbent has low acid, alkali, and salt resistance, which limits its application in some area, therefore, improve the acid, alkali, and salt resistance of the resin is particularly important.In order to prepare a superabsorbent with good resistance to acid, alkali and salt, and high absorb capacity for the saline solutions with different pH at ordinary temperature and pressure, this paper introducing interpenetrating networks (IPNs) technology, prepared two kinds of superabsorbent resin with interpenetrating polymer networks structure. The results can be summarized as follows:1. A superabsorbent (XG-AA-PVA) with interpenetrating polymer networks structure were prepared through solution polymerization using Acrylic acid (AA), polyvinyl alcohol (PVA) and Xanthan gum (XG) as raw materials and potassium persulfate(KPS) as initiator. The influence of different reaction conditions on product water-absorbency was studied. The water absorbing capacities of the products in various solutions with different pH and in different cation saline solutions were also systematically investigated. Results showed that the absorbent had high water absorbency over a wide pH range of 4-10, and the saturation time for water absorption was 5 min. Characterization analyses with IR, SEM and TG/DTG proved the formation of inter-penetrating network structure in the synthesized product. TG/DTG also showed the thermal stability of XG-AA-PVA was better than XG's.2. Sodium Polyvinyl alcohol sulfate(SPS) was prepared through the sulfonation of the hydroxyl groups of Polyvinyl alcohol(PVA). Its esterification degree was measured and it was 72%-74%. The IR analysis of SPS showed there were relatively strong vibration band of S=O at 1134cm-1 and 614cm-1,this result explained there was-OSO3- group on molecular chains of SPS.3. Using partly neutralized AA, XG and SPS as raw materials, KPS as initiator, N, N'-methylene bisacrylamide(NMBA) as crosslinker, prepared XG-g-AA superabsorbent interpenetrated with SPS(XG-AA-SPS) through solution polymerization. The reaction conditions that affected the water absorbent capability of the XG-AA-SPS were studied and optimized, determine the optimal synthetic conditions. The water absorbing capacities of the products in various solutions with different pH and in different cation saline solutions were also systematically investigated. Results showed that, after introducing-OSO3- groups, the acid, alkali, and salt resistance of the XG-AA-SPS resin are enhanced compared with the XG-AA-PVA resin. IR analysis showed that the existence of the-OSO3- groups in the XG-AA-SPS superabsorbent, TG/DTG analysis results showed that the introduction of-OSO3- groups raise the heat resistance of the XG-AA-SPS superabsorbent.