Synthesis And Surface-crosslinking Modification Of P(AA-AM)/Layered Mineral Superabsorbent Composite

Superabsorbent polymer is a special functional polymer material, which has a three-dimensional network structure with a suitable degree of crosslinking. The structures generally contain strong ionic hydrophilic functional groups, such as carboxyl, sulfonic acid group, hydroxyl. Superabsorbent polymers can absorb and retain a significant amount of water as high as hundreds of their own weights, and have an excellent performance of water retention under certain heat or pressure, and now they have been widely used in hygiene products, agriculture, health care, environmental protection and other areas.Surface of the layered mineral material generally contains many hydroxyl (-OH), active site, and large surface area, there are a large number of exchangeable cations between sheet layer. Add layered mineral materials to prepare P(AA-AM)/layered mineral superabsorbent composite, this method can improve absorbency, absorption rate, gel strength and thermal stability, and also expand the scope of application of layered mineral materials, reduce production cost.A series of P(AA-AM)/layered mineral superabsorbent composites were synthesized by free-radical polymerization in aqueous solution in the absence of nitrogen protection condition using AA, AM and layered mineral materials as raw materials, K2S2O8-Na2SO3 as the redox initiator and NMBA as the crosslinker. Some key factors affecting the water absorbency of the superabsorbent composites were considered, such as the reaction temperature, the amount of redox initiator, the amount of crosslinker, the neutralization degree of AA, the mass ratio of AA and AM, the addition amount of layered mineral materials. The structures of the superabsorbent composites were characterized by FTIR, SEM, TG and XRD, and the synthesis mechanism of the superabsorbent composites was also explored. Finally, The synthesized P(AA-AM)/layered mineral superabsorbent composites were modified by glycerol, aluminum chloride, ethanol and distilled water as surface-crosslinking modification liquid at 170℃.After modification, the superabsorbent composites were characterized by FTIR and SEM, absorption rate and water retention were also measured, the mechanism of surface-crosslinking modification was investigated. After surface-crosslinking modification, the superabsorbent composites become dispersible and non-sticky, and the absorption rate and gel strength were also improved.