Enthalpy relaxation in hyperquenched glasses of different fragility

The enthalpy relaxation in hyperquenched (HQ) glasses with a wide range of fragilities is studied by performing annealing and differential scanning calorimetric (DSC) experiments. In this work, the enthalpy relaxation behavior of annealed HQ glasses is characterized in terms of the excess heat capacity (Cp,exc) given by the difference between the first and the second DSC measurements on the HQ glasses. The shape of the Cp,exc curves depends on the fragility of the glass system, which implies that during annealing the mechanism of the structural relaxation of the HQ strong systems differs from that of the HQ fragile systems. The details of the fragility dependence of the Cp,exc curves have been discussed in terms of the energy landscape and the structure of the liquids.