在不同条件下材料拉伸粘度的敏感性Selectivity of extensional viscosity measurement under different conditions – melt elongation versus converging flow

Abstract：Elongational viscosity becomes more and more important due to increasing processing velocities in industrial processing. For film blowing, blow moulding and spinning process it is inevitable to consider elongational properties. The most important requirements for industrial application are - Fast testing with easy use - High selectivity - Elongation rates similar to processing - Online measurement. Several methods of measurement have been analyzed and some are introduced on the market but not under all aspects mentioned above. First an online elongational viscosity measurement on the basis of the so called “Rheotens” is presented in this work. This method of melt elongation is then compared with converging flow method (entrance pressure loss), were different calculations of elongational viscosity are used. Different lots of polyolefine types are selected for elongational viscosity measurement. The selectivity of both methods to material differences are compared discussing measurement uncertainty.