1. Determination of solid-state rheological properties

Mechanical spectroscopy tests enable us to measure certain characteristics, under well-defined mechanical and thermal stress conditions, which constitute solutions of the material's equation of state. This equation is a differential equation with respect to time, characteristic of polymer viscoelasticity. In practice, we don't try to explain it in its general form; we are content with certain particular solutions, determined experimentally for various stress laws. Given the structure of this equation, the characteristics measured are always functions of the loading time.

The physical viscoelastic characteristics (or characteristic functions) are obtained for stresses of low amplitude (linearity) whose variation as a function of time t or frequency f constitutes a true thermomechanical or rheological spectrum, an image of the material's structure.

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