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Glass Transition Temperature and Value of the Relaxation Time at T g in Vitreous Polymers
Author(s) -
Saiter Jean Marc,
Grenet Jean,
Dargent Eric,
Saiter Allisson,
Delbreilh Laurent
Publication year - 2007
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200751217
Subject(s) - fragility , glass transition , relaxation (psychology) , polymer , dielectric , materials science , thermodynamics , analytical chemistry (journal) , chemistry , composite material , organic chemistry , physics , optoelectronics , psychology , social psychology
Summary: Many works focused on glassy polymers determine values of glass transition temperature ( T g ) and an overview of the literature shows that depending on the method used, values of T g are found different for the same material. In this paper, a review of data collected on different materials are used and interpreted in term of molecular mobility characterized by relaxation time functions. By using three independent experimental procedures (dielectric, thermally depolarized current and calorimetric), we show that the value of the glass transition and the value of the relaxation time at T g can be correctly determined. It is also shown that the assumption: τ (Tg) = 100 s is constant, is not correct. The protocol proposed also allows the determination of the value of the fragility index “m” of the glass forming liquid with a great accuracy.