National Physical Laboratory

Multi-rate and extensional flow measurements using the melt flow rate instrument.


Rides, M, Allen, C R G, Dawson, A

Measurement Good Practice Guide No. 61, November 2002
NPL Doc. Ref:
PDB: 3431
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This guide presents the procedures and analyses necessary to carry out testing using new methods based on the use of the melt flow rate equipment for characterising the shear and extensional flow behaviours of polymer melts. These methods are- multiple flow rate testing, obtained through the use of various loads,- the use of an additional short-die geometry to quantify separately shear and extensional flow effects, and- extrudate swell and draw-down measurements, to assess the materials extensional flow behaviourThe multi-load test method will enable melt flow rate data to be extrapolated more reliably to higher shear rates. The use of the short die geometry and the measurement of extrudate draw-down will address the characterisation of the extensional flow behaviour of polymers that is often critical to their processability.These methods provide improved, yet affordable, materials quality control testing for polymers. Thus it is expected that the guide will be of particular value to those involved in quality control testing of materials, in particular where the production processes are dominated by extensional or stretching flows.

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