Slow structural relaxations of glass-forming Maltitol by modulated DSC calorimetry

The possibilities offered by the modulated differential scanning calorimetry technique to investigate the glass transition are analyzed and discussed on Maltitol. The technique provides specific tools to follow the structural relaxation in the frequency domain above Tg and in the time domain below Tg. Evidence is obtained that the complex heat capacity can be measured in the course of a routine differential scanning calorimetry (DSC) scan. The enthalpic relaxation can be analyzed which allows us to discuss the fragility degree of the glass former. The smearing effect of the underlying ramp is specifically investigated. It is shown that the method provides estimates both of the Vogel and of the Kauzmann temperatures. It thus offers an attractive way to check for a correlation between dynamics and thermodynamics. The concept of the "nonreversing'' component is used and discussed in order to study the slow sub-Tg relaxations. (C) 1999 American Institute of Physics. [S0021-9606(99)70621-5].