Thermal studies of Sulfamethazine to probe phase and state transitions by DSC

摘要

An amorphous form of a model drug,sulfamethazine, was prepared in-situ by coolingthe drug melt. The effect of cooling rate wasstudied to investigate changes inthermodynamic behavior; the enthalpy ofrelaxation, the glass transition temperature (Tg),heat capacity difference between initialcrystalline, super cooled liquid and glassy states(Cp), fragility and the time scales ofmolecular motions below the Tg.Cyclic thermal studies were performed toevaluate the proportion of glassy materialrelaxation after each cooling run by measuringTg and Cp across the Tg. Comparativestudies were also performed by ageing theglasses at different temperatures, These resultswere analyzed using VTF and Adams-Gibbsrelationships.