Glass transition of an epoxy resin induced by temperature, pressure and chemical conversion: a configurational entropy rationale

A comparative study is reported on the dynamics of a glass-forming epoxy resin when the glass transition is approached through different paths: cooling, compression, and polymerization. In particular, the influence of temperature, pressure and chemical conversion on the dynamics has been investigated by dielectric spectroscopy. Deep similarities are found in dynamic properties. A unified reading of our experimental results for the structural relaxation time is given in the framework of the Adam-Gibbs theory. The quantitative agreement with the experimental data is remarkable, joined with physical values of the fitting parameters. In particular, the fitting function of the isothermal tau(P) data gives a well reasonable prediction for the molar thermal expansion of the neat system, and the fitting function of the isobaric-isothermal tau(C) data under step- polymerization conforms to the prediction of diverging tau at complete conversion of the system.Comment: 16 pages, 8 figures, from the talk given at the 4th International Discussion Meeting on Relaxations in Complex Systems (IDMRCS), Hersonissos, Helaklion, Crete (Greece), 17-23 June 200