Molecular motions in a polycarbonate composite as studied by thermally stimulated recovery and dynamic mechanical analysis

The viscoelastic properties of a shore carbon-fibre reinforced polycarbonat e are studied in the glassy state and in the glass transition region by mea ns of Thermally Stimulated Recovery (TSR) and Dynamic Mechanical Analysis ( DMA) techniques in the flexural mode. The temperature calibration of the ap paratus is discussed. Each thermal sampling experiment is analysed accordin g to a simple Voigt-Kelvin model in which the temperature dependence of the retardation time follows the Arrhenius equation with two adjustable thermo kinetic parameters. Non-linear fittings of the experimental data are perfor med with the corresponding constitutive equation. Both the activation energ y and the pre-exponential factor follow the usual trends with temperature a nd present the well-known compensation phenomena. A divergence between the TSR results of the two materials is found above approximate to 145 degrees C and may be a result of the effect of the interface. The observed movement s in the glassy state which are still found to have a cooperative character are analysed according to the Adam-Gibbs theory. Dynamic-mechanical relaxa tion properties of the composite are reported and analysed in terms of Taka yanagi's block model.