The Frequency-Domain Analysis of the Rheological Data Acquired with Multi-function and All-electric Rheometer

The key parts of multi-function and all-electric rheometer (MAR) designed by the authors were introduced. The data processing method based on frequency-domain analysis were established. Intrinsic vibration displacement is defined to eliminate the effect of steady velocity displacement and extract the useful information of vibration displacement. The actual frequency, amplitude and phase of the superimposed vibration displacement and the entrance pressure were obtained by the frequency-domain analysis of the intrinsic vibration displacement and the entrance pressure. The control precision of the superimposed vibration displacement frequency and amplitude of MAR proved to be high. The direct current component of entrance pressure can be seen as the mean entrance pressure which stands for the flow resistance. The study of mean entrance pressure is useful in discovering the energy consumption mechanism of the polymer processing introduced vibration energy. Loss angle can be calculate according to the phase of entrance pressure and superimposed vibration displacement. The higher order harmonic of the entrance pressure can be used to characterize the nonlinear viscoelasticity of polymer melts. The factors which depend on the shear rate and influence the viscoelasitic properties can be studied by test the loss angle based on MAR.