An electric criterion to evaluate glass transition temperature dielectric relaxation measurements
BARRA, MARIO and CASSINESE, ANTONIO and GUIDO, STEFANO and TOMAIUOLO, GIOVANNA (2007) An electric criterion to evaluate glass transition temperature dielectric relaxation measurements. [Pubblicazione su rivista scientifica]
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In this contribution, a dielectric measurement technique for the evaluation of phase transition temperature and the study of physical aging on polymeric thin ﬁlms is considered. This kind of measurement provides the possibility of displaying phase transitions with a high degree of precision. Furthermore, it can be considered alternatively to techniques not applicable in the case of thin ﬁlms, such as Differential Scanning Calorimetry (DSC). In this work, owing to the high sensitivity of the utilized experimental set-up, a glass transition TG of 156 K, with a precision equal to 0.3%, and a melting TM=220 K have been assessed for 4 micron thick Polydimethylsiloxane (PDMS) ﬁlms. Performing measurement as a function of time, it was possible to monitor physical aging phenomena, mainly consisting in a change of dielectric properties. As expected, the time evolution of the aging phenomena can be described by a simple logarithmic law.
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