Oscillatory Measurements without Sample Inertia Effects Gap Loading

DYNAMIC (OSCILLATORY) MEASUREMENTS WITHOUT SAMPLE INERTIA EFFECTS ( GAP LOADING ) 

The ronaining sections of this chapter treat dynamic or oscillatory measurements of viscoelastic properties. Here, in simple shear, the experimental determination is usually a complex ratio of force to displacement (or torque to angular displacement) measured at a surface in contact with the sample or else a force measured 

The criteria for gap loading and surface loading conditions and the magnitude of errors introduced for finite ratios of gap thickness to shear wavelength have been critically examined by Schrag.  

In principle there is an intermediate case where the gap corresponds to one or several wavelengths and standing waves can be set up. This feature is rarely exploited in viscoelastic liquids because of their high damping characteristics. 

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