The RHEOGRAPH 20 is a high-pressure capillary rheometer according to DIN 54811 for determining the flow behavior and viscosity of thermoplastics, rubbers and oils. Highly filled polymer granules or powders are melted in a heated test cylinder and extruded from the capillaries with a stamp and a constant force or speed.

With a maximum test force of 20 kN and a maximum pressure of 1000 bar, viscosity measurements according to ISO 11443 can be carried out using various capillary types. Thus, the non-Newtonian behavior of highly viscous and filled materials can be reproduced at high process-relevant shear rates.

In addition to rheological parameters, thermodynamic properties such as the specific volume of the polymer as a function of temperature and pressure can be determined. These PVT measurements according to ISO 17744 are used to describe the shrinkage behavior during cooling in extrusion processes and to simulate injection molding processes. The measurements can be isothermal at constant temperature and change of pressure or isobaric at constant pressure with different cooling rates.

Furthermore, the RHEOGRAPH 20 can measure the thermal conductivity of polymers with TCM according to ASTM D5930. The maximum temperature is 500 °C with a maximum pressure of up to 1000 bar. The determined characteristic values characterize the material-specific behavior for the design of extrusion- or injection molding-based polymer processing.

The high-pressure capillary rheometer of the company Göttfert Werkstoff-Prüfmaschinen GmbH was financially supported by the European Regional Development Fund (2014-2020).

Contact: Alexander Ahrend M.Sc.; Benjamin Eichler