8. A Study for The Mechanism of Freezing and Thawing of Heterogeneous Systems(Synopsis paper presented at The 30th Annual Meeting)

Abstract

A mechanism of freezing and thawing of gels made from cross-linked dextrans (Sephadex) and water was investigated by using DSC and an ESR spin probe method. We obtained, from DSC, a strong suggestion that compartmentalized water by the network structure formed by cross-linkages of Sephadex G-25 remains unfrozen during cooling and crystallizes during subsequent warming. From ESR studies, however, no evidence which indicates the presence of liquid water was obtained below -50℃ with this gel system. A conceivable mechanism of anomalous crystallization observed with a Sephadex G-25-water system during warming(recrystallization) was proposed referring to changing of the network structure during both of freezing and thawing.