J. Phys. IV France 10 (2000) Pr7-243-Pr7-246
Dielectric and dilatometric studies of glass transitions in thin polymer filmsK. Fukao and Y. Miyamoto
Faculty of Integrated Human Studies, Kyoto University, Kyoto 606-8501, Japan
Dielectric relaxation and thermal expansion spectroscopy were made for thin polystyrene films in order to measure the temperature T[Math] corresponding to the peak in the loss component of susceptibility due to the [Math]-process and the [Math]-relaxation time [Math] as functions of film thickness d. While the glass transition temperature Tg decreases with decreasing film thickness, T[Math] and [Math] were found to remain almost constant for d > dc and decrease drastically for d < dc for high temperatures. Here, dc is a critical thickness. Near the glass transition temperature, the thickness dependence of T[Math] and [Math] is more prominent. The relation between the fragility index and non-exponentiallity is discussed for thin films of polystyrene.
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