Slow molecular mobility in the crystalline and amorphous solid states of glucose as studied by thermally stimulated depolarization currents (TSDC)

摘要

Thermally Stimulated Depolarization Currents (TSDC) measurements on alpha-D-glucose have been carried out in the temperature region from -165 degrees C (108 K) to 120 degrees C (393 K). The slow molecular mobility was characterized in the crystalline and in the glassy states, as well as in the glass transition region. The influence of aging on the measured TSDC peaks of the secondary relaxation has been discussed and it was concluded that there are motional modes that are aging independent while others are affected by aging. Important discrepancies were reported in the value of the steepness index or fragility (T-g-normalized temperature dependence of the relaxation time) obtained by different, and well-established, experimental techniques. A careful discussion of the possible origins of these discrepancies is presented. (C) 2008 Elsevier Ltd. All rights reserved.