Synthesis And Properties Of Chitosan-grafted And Inorganic-modified Superabsorbent Resins

Superabsorbent resins are a novel series of functional polymer materials, which have low degree of crosslinking and fine hydrophilicity. Being compared with traditional absorbent materials, superabsorbent have higher water absorbency, faster water absorption and better water retention, and their properties such as salt resistance and pressure resistance can be enhanced by chemical modification. Superabsorbent resins, as a series of functional polymer materials with great development potential, application value and economic benefits, have been widely applied in daily, medicine, health, agriculture and forestry, environmental protection, food, light industry and many other fields.Three novel superabsorbent resins have been synthesized by aqueous solution polymerization. Acrylic acid monomer and acrylamide monomer have been grafted onto chitosan macromolecule with initiator potassium persulfate and crosslinker N, N-dimethyl acrylamide, and modified with kaolinite, illite and silica nanoparticles. Fourier transform infrared spectroscopy characterization, scanning electron microscope observation and thermo-gravimetric analysis have been used to characterize the structure of the resins. Water absorbency of the resins has been tested, and the effect of synthesis conditions and external solution on the absorbency has been discussed.It is studied that chitosan-g-poly(acrylic acid/acrylamide)/silica polymer has a best performance on distilled water absorbency (470.6g/g), and is much better than the absorbency of kaolinite-modified resin (409/3g/g), illite-modified resin (363.3g/g) and none-modified resin. All the products have constant water absorbency in pH ranging from4to10.The result of TGA and DSC analysis shows that the mineral powders have grafted on chitosan by crosslinking effect with surface-hydroxyl in polymerization of kaolinite and illite modified resins, and silica modified resin has formed an IPN structure with inorganic silica sol network and organic chitosan-g-poly(acrylic acid/acrylamide) network. The images of SEM show the network structure of the resins with low degree of crosslinking and great specific surface area. It is an evidential structure to interpret the high water absorbency of the resins.