Berlin 2001 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
CPP: Chemische Physik und Polymerphysik
CPP 16: Poster: Dynamics of Molecular Systems, Polymer Dynamics, Glass Transition, Crystallization, Electronic Properties of Polymers
CPP 16.16: Poster
Montag, 2. April 2001, 12:30–15:00, AT1
Calorimetric indication of crossover region for dynamic glass transition? — •E. Hempel and E. Donth — FB Physik, Universität Halle, D-06099 Halle
Temperature modulated differential scanning calorimetry (TMDSC) is presented in a wide temperature region around the crossover temperature Tc for five polymers and two small-molecule organic glass formers. The entropy change δ S possibly connected with the crossover region is estimated from a bend or a step of the TMDSC trace. For no bend nor step, a maximum amount of δ S is estimated from the noise of the trace. Within the experimental uncertainties, δ S is of the order, or smaller than 5 percent of an analogously determined δ Sg at the glass temperature Tg. In any case, δ S is smaller than 0.01R with R the molar gas constant.