Paper presented at the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Turkey, 19-21 July, 2010.
Measurement of elongational viscosity of polymer materials seems to be much more complicated in comparison with measurement of shear viscosity. The problems concern preparation of the polymer samples (i.e. their homogeneity and geometrical accuracy), fixing of both ends, influence of gravitational force, etc. Usage of the individual devices for measurement of elongational viscosity differs, among other things, by an aspect ratio of the
prepared samples. In contrast to 'classical' devices developed in 80s' using oblong samples, a recently proposed SER Universal Testing Platform enables to apply rectangular samples of moderate aspect ratio. However, in context with this ratio, there has been recently discussed [I] a possible appearance of planar elongation during measurement of uniaxial elongational viscosity. The aim of this contribution is to document - for material used (LOPE Escorene, Exxon, USA)- the invariantness of the elongational viscosity measured with respect to sample widths and thicknesses (within sufficiently broad regions). Temperature was set to 180'C.