An investigation of high rate capillary extrusion rheometry of thermoplastics

作者：Rides Martin^*; Kelly Adrian L; Allen Crispin R G

来源：Polymer Testing, 2011, 30(8): 916-924.

DOI：10.1016/j.polymertesting.2011.08.011

• Rheometry
• Extrusion
• High shear rate
• Shear viscosity
• Polymer
• Plastics

An intercomparison was undertaken to assess the reproducibility of shear viscosity results obtained at high shear rates using extrusion rheometers including an instrumented injection moulding machine. Shear viscosities were obtained at shear rates up to 6 x 10(6) s(-1). The high shear rate results demonstrated good agreement for viscosities up to shear rates of 2 x 10(5) s(-1), with results varying typically by no more than +/- 25%. This level of reproducibility was considered favourable compared with the reproducibility of +/- 28% (95% confidence) identified for capillary extrusion rheometry at lower shear rates [ISO 11443]. At higher shear rates, e.g. >360,000 s(-1) for polystyrene, deviations in the shear thinning behaviour were apparent, potentially linked to the pressure dependence of viscosity. The effect of the Rabinowitsch correction on shear viscosity data has been highlighted: for the high density polyethylene, which had a low shear thinning coefficient n value, the correction potentially introduces a large uncertainty in the corrected viscosity values at high shear rates.

• 出版日期2011-12