UV Polymerization Of Acrylic Acid Based High-strength, Fast-water Absorbing Resins And Grafting Modification

Acrylic acid based superabsorbents are the most popular resins in the research field of superabsorbents, synthesized commonly by solution polymerization and suspension polymerization. This kind of absorbents exist some defects including high costing, low gel strength, slower absorption rate and complexed synthetic method. What is more majority of present literatures inclined to improve water absorbency and salt- tolerance of the resins. Adopting UV polymerization is of great convenience and cellulose has the advantages of extensive source, easily degradable, initially fast absorbing, indicating that using cellulose into absorbent resins can attribute to descending the cost and improving the degradability, gel strength and absorption rate of the resins.In this paper three parts of contents were studied:1)The polymerization condition of high-strength, fast-water absorbing poly acrylic acid by UV polymerization; 2)The synthesis condition of copolymerization grafting acrylic acid(AA) onto various cellulose system including homogeneous cellulose(HOC), heterogeneous cellulose(He C) and methylcellulose(MC) by UV polymerization respectively; 3)Optimum modification condition of methylcellulose using maleic anhydride and the condition of copolymerization of maleyl methylcellulose with acrylic acid by UV polymerization. As a result, five kinds of high-strength, fast-water absorbing resins: PAA,PAA-g-He C, PAA-g-HOC, PAA-g-MC, PAA-co-MC-g-MA were obtained.1. The optimal synthesis condition of PAA by UV polymerization was: the concentration of AA was 25%, exposure time was 45 min, neutralization degree was 75%, the amount of initiator was 0.1% and the amount of crosslinks was 0.04%.Average absorption rate of PAA synthesized at optimal condition in distilled water and saline(0.9% Na Cl solution) was 78g/g.min and 15g/g.min respectively. The obtained resin can retain more than 20% water after for 8d under 2000 Pa and for 4d even under 8000 Pa, displaying excellent gel strength.2. The optimum synthesis condition of PAA-g-He C was : amount of cellulose was 14%, exposure time was 40 min, neutralization degree was 70%, the amount of initiator was 0.1%; The optimum synthesis condition of PAA-g-HOC was : amount of cellulose aqueous was 10%, exposure time was 50 min, the amount of initiator was 0.3%; The optimum synthesis condition of PAA-g-MC was : amount of methylcellulose was 20%, exposure time was 50 min, neutralization degree was 65%, the amount of initiator was 0.3%; Average absorption rate of PAA-g-MC under less than 4000 Pa pressure was faster than the resins used in both of diapers domestic and exotic. Both of PAA-g-He C and PAA-g-MC displayed excellent gel strength and can suspend the load pressing on them for several days. Acetone treatment has a great impact on the absorption rate of the resins. Before acetone treatment, the average absorption rate of the resins within 1min were lower than the resins used in both of diapers domestic and exotic, whereas all of them exceeded exotic diaper and the absorption rate of PAA-g-MC turned to even faster than domestic diaper after acetone treatment.3.The optimal synthesis condition of PAA-co-MC-g-MA was: the amount of MA-g-MC was 12%, substitution degree(SD) of MA-g-MC was 0.568, exposure time was 50 min, the amount of initiator was 0.4%; The absorption rate of PAA-co-MC-g-MA synthesized at optimal condition in distilled water and saline under 8000 Pa reached to 8g/g.min and 3g/g.min respectively and can retain more than 20% water for several days ranging from 7d to 3d under load ranging from 2000 Pa to 8000 Pa.