In general, the mechanical properties of materials depend on frequency. A good understanding of the influence of frequency on a material is therefore very important for its practical use. For example, a material appears stiff under the action of a force at high frequency, but soft when the force is applied slowly.
Two frequency ranges are available:
- 0.001 to 200 Hz
- 0.001 to 1000 Hz
An excellent temperature stability and accuracy together with the possibility of measurements at high frequencies allow the precise and rapid construction of master curves. Besides information on dynamic material behavior, conclusions can also be drawn on the molecular structure and network.
The behavior of viscoelastic materials like polymers depends on frequency and temperature.
In general, there is equivalence between frequency and temperature behavior during transition processes. Since the frequency dependence is directly related to time dependences, the relationship is usually referred to as the Time-Temperature Superposition principle (TTS).
In this example, TTS was used to create the SBR master curves.
The TTS principle is the theoretical basis of the master curve technique. The master curve is often used to predict the material performance at frequencies outside the range that can be measured with a dynamic mechanical analyzer.
TTS is not applicable to all kinds of samples. For such samples, e.g. filled polymers, a large frequency range is a huge advantage.
|In this example, the full frequency range was used.|
For frequency sweeps normally the higher frequencies are preferred because of a shorter experiment time.