Investigation of the glass transition on atactic polystyrene by isothermal internal friction measurements

This article presents the first results obtained on atactic polystyrene thanks to a new method, allowing isothermal internal friction measurements. The wide range of available frequencies allows us to show that the glass transition in polystyrene corresponds to a single relaxation time process, due for example to a stress induced reorientation of the chain bonds that make up the macromolecules. The temperature dependance of the relaxation strength seems to indicate the presence of a pseudo critical temperature (Tc = 175 K), well below the glass transition temperature, corresponding to a second order thermodynamic transition