Rides, M; Allen, C R G (2001) High rate extensional rheometry of polymer melts. NPL Report. MATC(A)71

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Abstract

The NPL extensional rheometer has been developed further to test polymer melts at high strain rates. Results of extensional viscosity measurements up to nominal strain of 100s-1 for several polyethylene melts are reported. Repeatability of the results is demonstrated to be good, even at the highest rate. The materials exhibit significant differences in their behaviour, particularly in their additional strain hardening to failure. Sources of error due to the acceleration of the motor and the differences observed between the set and measured strain rates have been investigated, and the magnitude of these errors estimated. The effect of these errors on the measurement of tensile stress growth coefficient values (transient extensional viscosities) has been determined using an analysis of measurement uncertainties. This showed that the errors increase significantly as strain rate increased, and also for increasing strains above a value of approximately 1.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	MATC(A)71
Subjects:	Advanced Materials Advanced Materials > Polymer Rheology
Last Modified:	02 Feb 2018 13:17
URI:	http://eprintspublications.npl.co.uk/id/eprint/2459

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