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Adam-Gibbs formulation of enthalpy relaxation near the glass transition

1997; The National Institute of Standards and Technology; Volume: 102; Issue: 2 Linguagem: Inglês

10.6028/jres.102.015

2165-7254

Ian M. Hodge,

Thermodynamic properties of mixtures

The entropically based nonlinear Adam-Gibbs equation is discussed in the context of phenomenologies for nonlinear enthalpy relaxation within the glass transition temperature range.In many materials for which adequate data are available, the nonlinear Adam-Gibbs parameters are physically reasonable and agree with those obtained from linear relaxation data and thermodynamic extrapolations.Observed correlations between the traditional Tool-Narayanaswamy-Moynihan parameters are rationalized in terms of the Adam-Gibbs primary activation energy (⌬ ) determin-ing how close the kinetic glass transition temperature can get to the thermodynamic Kauzmann temperature.It is shown that increased nonlinearity in the glass transition temperature range is associated with greater fragility in the liquid/rubber state above Tg.