Preparation And Properties Of Polyacrylic Acid Base Superabsorbent Modified By Starch Grafting/Binary Copolymerization

This paper aiming at the defects of the structure and performance of traditional polyacrylic acid/sodium superabsorbent,the thesis adopts starch graft modification,binary copolymerization modification,reversible fracture-addition chain transfer polymerization and click reaction combination method,using acrylic acid,acrylamide Sodium allyl sulfonate,starch,are used as raw materials to prepare modified super absorbent.FTIR,TG,SEM and other means were used to characterize the microstructure,and various properties of the resin such as water absorption and water retention were tested.The research results are as follows:(1)Starch,acrylic acid and acrylamide(AM)are used as main raw materials,and starch-acrylic acid-acrylamide superabsorbent is prepared by aqueous solution polymerization.The optimized process parameters are 2 wt% and 0.5 wt% of initiator and crosslinking agent,AM /AA molar ratio of 3:8,monomer /starch mass ratio of 8: 1,acrylic acid neutralization degree 85%,The absorption rate of the superabsorbent prepared under optimized conditions to deionized water and physiological saline was1089.6g/g and 80.5g/g,respectively.The process conditions for preparing superabsorbent were optimized by orthogonal experiments,and the influence of the monomer AM/AA molar ratio on the structure and properties of superabsorbent was studied by a single factor method.The results show that with the increase of monomer AM/AA molar ratio,and the decrease in the pores and the network density of the resin,the van der Waals force and hydrogen bonding between the resin molecules increase,and the water retention performance of the resin is correspondingly improved.(2)Ammonium persulfate is used as the initiator and N,N-methylenebisacrylamide is used as the cross-linking agent to introduce a more hydrophilic sulfonic acid group into the sodium polyacrylate super absorbent resin by copolymerization.A new acrylic(AA)copolymerized sodium allyl sulfonate(SAS)superabsorbent was prepared.The single-factor method was used to optimize the reaction process parameters.When the AA: SAS mass ratio was 10: 2,the superabsorbent prepared had the highest absorption rates for deionized water and physiological saline,which were 1378.9 g/g and 98.8respectively g /g;Compared with PAA/Na superabsorbent,the water absorption rate and salt resistance are improved by 40.1% and 34.3%,respectively.(3)In order to solve the problem of irregular structure of the cross-linked structure of the traditional high-absorbency resin prepared by free radical polymerization,resultingin unclear material structure,the method of combining reversible fracture-addition chain transfer polymerization(RAFT)and click reaction was used to fit the network structure The controllable polyacrylic acid superabsorbent resin has made a preliminary discussion to precisely regulate the network structure of the superabsorbent.