1998 Volume 46 Issue 5 Pages 822-825
Glassy tri-O-methyl-β-cyclodextrin (TMCD) was prepared by cooling the melt and the glassy state was confirmed by measuring the glass transition temperature (Tg) and the anomalous endothermic peak (heat capacity maximum) on a differential scanning calorimetry (DSC) curve. Glassy TMCD showed a glass transition at 356 K and an anomalous endothermic peak. The value of the ratio of Tg and the melting temperature (Tm) of TMCD was 0.83. The influence of the heating rate of the glass prepared at the cooling rate of -1.25 K/min on the glass transition was examined, and the apparent activation energy of glass transition was calculated to be 223.4 kJ/mol. The rate and quantity of relaxation of glass was determined by the area under the anomalous endothermic peak of the DSC curves of glasses prepared at various cooling rates, that of glassy TMCD was found to be extremely large. Enthalpy relaxation during the isothermal aging of glassy TMCD occurred most remarkably at 341 K. Devitrification of glassy TMCD did not occur for more than 1.5 years at 25°C. Pulverized glassy TMCD remained as glass for 1 year. Glassy TMCD was very stable and TMCD was found to be a good glass-former.
