Advanced rheological characterisation for thermal sensitive materials using shear heating device

Abstract

In predictive engineering for polymer processes, the rheological data is the most important data to end up with good prediction of processing parameters. In case of materials which are highly temperature sensitive and have a low bulk density, one has to be sure that the obtained data is representative for the future processing. One should avoid applying unrealistic conditions to the material causing unacceptable degradation of the material. To cover this issue, an advanced capillary rheometer has been developed which is able to heat the material to be tested in an advanced way. Simply conductive heating is combined with some controllable shearing resulting in measurement times which are only some minutes. Using a standard capillary rheometer, measurement times are most often more than ten minutes. The main disadvantage of this fast measuring technique is the sample temperature. To illustrate the good functioning of this equipment together with the validity of the results, a comparative reference measurement is set up for a non thermal sensitive material. This approach also allows to investigate the influence of the different settings influencing the shearing within the sample preparation for the shear viscosity measurement. Based on these promising results, the advanced rheometer can be used to perform accurate measurements for thermal sensitive materials as there are PVC. PVC is typically provided in powder form as raw material. While processing this material, it is highly sensitive for slip at the wall. Some promising results are obtained using this equipment.