Synthesis And Characterization Of Super Absorbent Resin

Super absorbent resin (SAR) is a novel water梥welling functional polymeric materials, which usually have the hydrophilic groups, such as earboxyl and hydroxy, and retain a certain extent cross條inking structure. SAR can absorb several hundred times or several thousand times as much water as its own weight, owning to its high capacity for absorbing water, high degree of water retention under pressure. SAR, being insoluble in water and organic solvent, is a three? dimensional network polymer, which is polyelectrolyte. In this paper, the framework of SAR is synthesized based on copolymer of methyl acrylate(MA) and vinyl acetate(VAC) [P(MA梒o--VAC)]. Copolymerization reaction of MA and VAC is simulated by microcomputer. The relationship of the copolymeric composition curve of Fl梖l, the curve of C桭, and the order distribution of the copolymerization reaction are presented by microcomputer. Several important physical properties parameters, such as specific volume Vp, solubility parameter 6, and glass transition temperature Tg, have been determined by group contribution method using microcomputer. The partially hydrolyzed copolymer [HP(MA梕oVAC)1 is a kind of SAR with high water absorption and water梙olding, but it has lower gel strength and salt resistance. The relations between the water absorption capacities of the copolymer and the amount of initiator, crosslinking agent used, the reaction V ~LI~眛~z~ temperature, time, monomer/water and the degree of hydrohysis were studied. The water absorbing mechanisms of HP(MA梒o梀AC) are discussed. In order to improve the properties of water梐bsorption, gel strength and/or salt resistance, the HP(MA梒o梀AC) is modified by grafting the monomer of acrylonitrile(AN) using the initiator K2S208. The graft reaction is made sure by FR桱R. The percentage of grafting (PG[%1) and the grafting efficiency (GE[%]) are determined. The experimental results showthat the properties, such as water absorption capacities, absorption rate, water retention, thermal stability, recovery properties, and salt resistance, can be modified by hydrolyzing graft copo 1 ymer. Through grafting and then hydrolyzing, the cross條inking density of the graft copolymer is improved, consequently the gel strength is increased; at the same time, the more hydrophiiic groups, such as 桟ONH2, 桟OOH, and/or 桟OONa are obtained after the .桟N is saponificated. It is obvious that the water梐bsorbing capacity of the SAR is increased very much. The properties of water retention, recovery of SAR and temperature and pH sensitive of hydrogel are investigated. Several relevant influential factors are inspected, such as crosslinker, time, initiator, acid, alkali, and salt. The applications on agriculture water retention and fighting a drought, industrial dehydrant, drug delayed release materials, and energy梥toring materials of SAR are pilot studied.