Measuring the pressure dependent viscosity at high shear rates using a new rheological injection mould

摘要

To shorten the development time for injection moulded parts, process simulations in different developing steps as well as quick and accurate measurements of rheological data even for the increasing variety of special compounds are necessary. For simulation of thin wall injection moulding accurate viscosity data measured at shear rates up to 800.000 s~(-1) and more are important, hut not available in any commercial material database. Therefore, within the EU project "Pro4Plast", an easy-to-handle rheological measurement system was developed by the Institute of Polymer Processing, Montanuniversitaet Leoben, Austria. The rheological mould is constructed like a standard injection mould with interchangeable dies. It can be mounted onto any conventional injection moulding machine and enables operators (manufacturers, especially SMEs) to measure viscosity in time on their own machines at practically relevant shear rates (from 100s~(-1) to 2. 10 s~(-1)). A special feature allows measuring the pressure dependency of viscosity using closed-loop counter pressure control. Experimental data are evaluated taking into account the melt temperature rise due to dissipative heating.