| Applying the molecule structure design theory to the synthesis of super absorbent (SAP), using acrylic acid (AA), 2-acrylamido-2-methylpropane-sulfonic acid (AMPS), montmorillonite (MMT) and sodium alginate (SA) as main materials, PAA/MMT, PAA/AMPS/MMT, PAA/SA super absorbent were designed and synthesized by inverse suspension polymerization. The factors that influence the capability of the SAP have been investigated, the absorbency, water-keeping capacity, salt tolerant capacity, thermal stability, biodegradability and structure have been studied.Organic MMT has been prepared by two-step intercalation method using DMC and CTAB. The experiment results showed that the interlayer distance of organic MMT prepared by two-step intercalation method has been enlarged from 1.26nm to 3.07nm, it is in favor of the intercalation reaction of PAA with MMT. The results proved that two-step intercalation method is a better method for preparing organic MMT.The experiment results indicated that inverse suspension polymerization is a better method for synthesizing SAP, it can avoid SAP absorb a great deal of water, the products is small particles, it is in favor of polymerization reaction and after treatment of the products. The influence of reaction conditions, such as the sort of dispersion medium, oil/water ratio, the sort and amount of dispersant, on the capacity of SAP were discussed. The results showed it is better that using cyclohexane as dispersion medium, the volume ratio of cyclohexane to water was 3:1, and using Span-60 and Tween-80 as dispersants and their mass ratio was 2:1. The synthetic conditions were researched systematically. The suitable synthetic conditions were as following:PAA/MMT super absorbent: Base on cyclohexane, the mass fraction of dispersants was 2%, based on AA, the mass fraction of crosslinking agent(NMBA), initiator (KPS) and MMT were 0.1%, 2% and 10%, respectively. The neutralization degree of AA was 70%, the reaction temperature was 70℃. The absorbency of the products synthesized under these conditions is 783g/g for distilled water and is 86g/g for 0.9% NaCl solution.PAA/AMPS/MMT super absorbent: Base on cyclohexane, the mass fraction of dispersant was 2%, based on AA and AMPS, the mass fraction of crosslinking agent... |
