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.

This study focuses on the heating stage of the rotational molding process. When the mold wall reaches the tacky temperature, free flowing powder starts to adhere, melt, and sinter. In this work, a new modeling strategy is proposed. Compared with the models found in the literature, the model combines the use of a tacky temperature for the adherence of powder, changing boundary conditions, and thermophysical properties as function of temperature and the degree of sintering. The changing boundary conditions are introduced to take into account both wall to air and wall to powder contact. The calculation of the temperature evolution is done by applying the thermal finite difference principle to elements with a fixed polymer mass. The modeling of a uniaxial rotating cylinder is chosen as a case study. The validation is done for an amorphous polycarbonate resin. The performance of the model is evaluated not only by the comparison of temperature‐time data as is the case in most literature, but also by the decrease in free flowing powder weight as function of time, visual data from an in‐mold looking camera, and through thickness analysis of the molded pieces at various moments in the heating process.