Abstract
Chemical structure and some properties of a super absorbent consisted of crosslinked starch-grafted-polyacrylic acid and its sodium salt were studied. From the results of studies on the chemical structure, we disclosed that acrylic acid and its sodium salt are graff-polymerized on starch by ratio of 2 molecules to one glucosic unit of starch, and the grafted polyacrylic acid and sodium salt are slightly crosslinked. At the same time of the graft-polymerization, the interaction by hydrogen-bond between carboxylic acid and hydroxy group is formed. The super absorbent has the absorbing capacity of about 400ml/g in water and retains about 80% of the absorbnd water even under pressure of 2kg/cm2. Although the super absorbent swells and becomes gel-like in water, it changes to a homogeneous solution and viscosity of it is reduced, wheh it is given mechanical shear. The homogeneous solution thus obtained gives a clear and highly hygroscopic film by casting and drying.
