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Review of the need and measurement methods for multi-axial testing of polymer melt rheology.

Rides, M (2002) Review of the need and measurement methods for multi-axial testing of polymer melt rheology. NPL Report. MATC(A)32

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A review of the methods for measuring multi-axial extensional viscosity of polymer melts is presented. The unique rotating clamp multi-axial extensional rheometer developed by Meissner represents the current state of the art in measurement technology, with the capability for measurement in various modes of deformation and more recently at elevated temperature for polymer melts. Techniques that approximate to controlled measurements (measurement in which applied strain rate or stress is constant) include the bubble inflation and the lubricated squeeze flow methods. However, use of these approximate methods is still very limited.
Several factors may influence the need for methods to determine multi-axial data. Firstly, there have been recent significant advances in constitutive modelling that enables the prediction of multi-axial properties with greater confidence. Secondly, there is evidence that indicates that upper and lower bounds to multi-axial extensional viscosity data are given by uniaxial extensional viscosity and simply shear data. Finally, The greatest additional strain hardening is exhibited by uniaxial extensional data and is thus a more suitable property for discriminating differences in materials as necessary, for example, for materials selection for quality control. Combining these factors the need for experimental methods for determining multi-axial data is considerably reduced, especially considering the difficulty of such measurements.

Item Type: Report/Guide (NPL Report)
NPL Report No.: MATC(A)32
Keywords: lubricated squeeze flow, bubble inflation
Subjects: Advanced Materials
Advanced Materials > Polymer Rheology
Last Modified: 02 Feb 2018 13:17
URI: http://eprintspublications.npl.co.uk/id/eprint/2425

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