Thermal Analysis Studies of Glass Dispersion Systems

Abstract Glass dispersion systems were examined using differential scanning calorimetry. The addition of a crystalline additive to a glassy vehicle resulted in a reduction of the vehicle's glass transition temperature. Mixtures of glassy materials were immiscible, partially miscible, or completely miscible. The results can be explained using the concept of miscibility among liquids. By combining two miscible glasses in the proper ratio, it was possible to obtain greater physical stability than with either of its glassy components. This was demonstrated with a 1:1 mixture of citric acid and acetaminophen which showed no changes in its thermogram after seven weeks of storage at 23°C. The glass transition of this mixture is about 18° C.