Study On Synthesis And Properties Of Hydroxyethyl Cellulose-based Superabsorbent

Superabsorbent polymers (SAP) are new type of functional polymer materials which can absorb and hold a large amount of water even under pressure. These materials have been widely used in many fields on account of their excellent properties. The research on cellulose-based superabsorbent is less comparing with starch-based and synthetic polymer superabsorbent. Preparation and properties of hydroxyethyl cellulose-based superabsorbent are studied in the dissertation.1) Hydroxyethyl cellulose - graft - acrylamide superabsorbent (HEC-g-AM) was synthesized by aqueous solution polymerization on the conditions of potassium sulfate and sodium bisulfite as initiator, N,N' -methylene-bis-acrylamide as crosslinker. The graft polymerization mechanism was discussed. The influence of reaction temperature, the amount of initiator and crosslinker, the ratio of monomer to HEC, and the concentration of sodium hydroxide on the absorbency of the SAP was investigated. The structure and properties were characterized by IR, TA, and XRD. The results were as following: the fitting temperature of polymerization was 50 C, the ratio of AM to HEC was 8:1, the amount of the initiator and crosslinker were 0.06% and 0.9% of the monomer respectively. The distilled water absorbency of the SAP is 1360g/g, and the saline water (0.9% NaCl) absorbency is 115g/g.2) Hydroxyethyl cellulose-graft-acrylamide/SiO2 superabsorbent composite (HEC-g-AM/SiO2) was prepared by sol-in situ polymerization, basing on the technology process of HEC-g-AM superabsorbent. The influence of the amount of silica sol, initiator and crosslinker on the absorbency of the SAP composite was investigated. Water-retain ability, thermal stability and relationship between water-absorption speed and size were studied. The structure and properties were characterized by IR, TA, XRD, SEM. The results indicated that the suitable amount of silica sol is 7% of the monomer; the distilled water absorbency is 1120g/g, and the saline water (0.9% NaCl) absorbency is 105g/g; the amount of crosslinker reduced and the amount of initiator increased comparing with the preparation of HEC-g-AM superabsorbent. Furthermore, the thermalstability improved.3) The swelling properties of HEC-g-AM and HEC-g-AM/SiOa superabsorbent were investigated on the conditions of different saline solution, different pH value and different solvent solution. The results indicated: the water absorbency decreased with the salt concentration, ion value and the solvent concentration increasing; the water absorption ability decreased if pH value is too high or low. The thermodynamic behavior of the hydrogel was analyzed by DSC. The results showed that phase inversion temperature increased with water of the hydrogel increasing,...