GELATION MECHANISM OF METHYLHYDROXYPROPYLCELLULOSE IN AQUEOUS-SOLUTION

The reversible gelation behavior of methylhydroxypropylcellulose aqueous solutions was observed on heating and cooling by means of differential scanning calorimetry (DSC) and time-resolved small angle X-ray scattering (SAXS). DSC results indicate that the gelation proceeds in two steps and the structuring or destructuring of water along polysaccharide chains was responsible for the observed thermal behavior. An extent of inhomogeneity evaluated from the SAXS profile was found to increase from 4-5 nm in sol to a few tens nm upon gelation. It was speculated that gelation takes place by the fringed micelle formation with a large size distribution and by the subsequent phase separation.