Combined isothermal and thermally stimulated depolarization measurements in polymers interpreted with the modified coupling model of relaxation

Marchal, Eve
October 1996
Journal of Chemical Physics;10/8/1996, Vol. 105 Issue 14, p6068
Academic Journal
In Ngai’s coupling model, the relaxation rate of bulk amorphous polymers has a power law time dependence which can be measured by isothermal depolarization. We propose a method by which the time needed for one experiment is considerably shortened without loss of information. At temperatures below and above the liquid glass transition we have previously modified Ngai’s model by introducing a parameter t′ which replaces the physical time, while the other parameters of the model are constant. The above experimental method can be used to probe the hypothesis. This is illustrated for an amorphous poly(ethyleneterephtalate) sample studied below Tg. Above Tg the thermally stimulated depolarization current was analyzed for polystyrene. At the α-β bifurcation temperature it appears that t′=t.


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