Test methodEvaluation of rheological properties of non-Newtonian fluids in micro rheology compounder: Experimental procedures for a reliable polymer melt viscosity measurement

The aim of this report is to develop an experimental method which provides relevant data about the rheological behaviour of polymer melts using a Haake minilab microcompounder. A slit capillary die integrated in the recirculation channel of the microcompounder allows determination of polymer flow characteristics using two pressure transducers specially designed for this purpose. According to a specific methodology detailed in the present paper, the effective flow rate and the corresponding apparent shear rate were carefully investigated as regards the repeatability of the data. The viscosity of different commercial polymeric materials (polyolefins and polyamide 6) exhibiting different melt flow rate properties was then calculated based on the Hagen-Poiseuille theory. The results show that the melt flow data obtained from the micro-rheology compounder overlap very well with the shear data obtained using oscillatory or rod capillary rheometers according to the Cox-Merz rule. Finally, a possible application of viscosity measurements of the developed method is given. Using the morphological analysis of a PP/PA6 (80/20 w/w) sample as a polymeric blend model, a deduction of an interfacial tension factor was highlighted and a pertinent value corresponding to that found in the literature was assessed.