Pinning of phase separation of aqueous solution of hydroxypropylmethylcellulose by gelation

Opalescence of the aqueous solution of hydroxypropylmethylcellulose (HPMC) induced by heating has been studied in terms of the phase diagram and the p hase separation dynamics. The cloud point curve and the sol-to-gel transiti on curve intersected with each other at about 55 degrees C. Just above the cloud-point curve at which the spinodal curve has its minimum, a ring-like scattering pattern appeared corresponding to the spinodal decomposition. Te mporal growth of the scattering function in the course of phase separation was studied by a time-resolved light scattering technique. The gelation pin ned the phase separation (spinodal decomposition) of the aqueous HPMC solut ion. (C) 1999 Elsevier Science B.V. All rights: reserved.