Certech recently invested in two complementary rheometers for the characterization of the rheological behaviour in the molten state of filled or unfilled polymeric materials:
• The high-pressure capillary rheometer covers the range of high shear rates corresponding to the different polymer processing techniques (extrusion, injection, etc.). This rheometer has a temperature range of up to 400°C and can reach a maximum pressure of 1400 bar, allowing to characterize technical polymers (PEEK, etc.) or polymers with very high viscosities (very low index of fluidity, MFI). It is equipped with a double sheath 15 mm in diameter in Böhler M-390 steel which gives it very good resistance to abrasion and corrosion. The use of several capillaries allows to carry out of numerous mathematical corrections (Bagley, Rabinowitsch-Weissenberg, etc.) and to meet the current standards for viscosity measurement, namely ISO 11443 and ASTM D3835.
• The rotational rheometer covers the range of low shear rates and can be configured according to several methods to characterize polymers in the molten state or in solution. Different geometries are available: Couette for low-viscosity liquids, plate-plate or cone-plate for polymer melts, and torsional tests for solid samples. To cover a maximum of applications, the force sensor is separated from the motor, which makes it possible to carry out controlled tests in deformation and stress. Temperature scanning (between -160°C and 600°C) makes it possible to measure the transitions. The instrument software also allows for more complex data interpretation with calculation modules for the application of the principle of temperature-time superposition (TTS) and for measuring the molecular weight distributions of polymers (MWD). The pressure cell, an accessory available from Certech, allows the measurement of the viscosity of solutions at temperatures close to or above the boiling point of the solvent (200°C) or under supercritical conditions (150 bars).
Certech’s technology platform allows the complete characterization of materials (chemical, physical, mechanical and sensory properties).