Oscillation. Rotation. Process Analyzation

To better understand the manufacturing process of an unvulcanized rubber compound, the steady shear viscosity is one of the most important properties, especially crucial for determining the process parameters for extrusion and injection molding purposes.
The RPA ultra's rotating lower die with unlimited strain thus provides the user with a dual test mode: dynamic and steady shear.

A significant challenge in the processing of rubber compounds is the issue of Wall Slip.
This is a rheological phenomenon where slippage occurs, for example, between the extruder wall and the flowing material.
We offer an optional solution where the upper die is replaced by a defined polished die set. In combination with a programmable internal pressure, this allows Wall Slip experiments to be carried out.

One of the most common and important tests performed on rubber compounds are the isothermal cure tests.
All important test parameters such as maximum and minimum torque, TC values, reaction time and rate, etc. are determined and made available to the user in tabular or/and graphical form for further analysis in the BareissOne software.

In order to evaluate the behavior of a sample over a wide temperature range, non-isothermal measurements (temperature sweep) are typically performed at different heating rates. This measurement at different heating rates also paves the way for kinetic calculations - a module that is also integrated into the BareissOne software.

By characterizing a sample over a wide range of frequencies, the user obtains a comprehensive overview of the viscoelastic behavior as well as the molecular structure (molecular weight and molecular weight distribution).
Viscoelastic properties such as complex modulus, elastic modulus, loss modulus, complex viscosity, phase angle, etc. are calculated at each frequency as a result of the frequency-dependent behavior of the sample.

Measuring a specimen over a wide strain range shows the strain-dependent behavior, e.g., the linear viscoelastic range (LVE) up to Large Amplitude Oscillatory Shear (LAOS). The Payne test, which is performed at small strain amplitudes to investigate the (filler/polymer) filler networks, reveals information about the filler content and the filler dispersion levels.

LAOS is essentially a strain sweep performed at relatively large amplitudes to investigate and evaluate the nonlinear viscoelastic behavior of a sample.
The nonlinear behavior of a material is based on its polymer architecture --> linear or branched polymer.
The LAOS results are also used for FT- Rheology. The calculation of the LCB index (Long Chain Branching) or the Q parameter is performed using the harmonic spectrum from Fourier analysis (FFT).