Bulk viscoelasticity experimental methods

For details on the experimental procedures and analyses, including pitfalls, the reader is referred to the mentioned reviews and in particular the work in [73,74], We treat below a simplified case. In practice, it is found that the application of these methods to polymers often leads to overestimates of moduli compared to bulk measurements. This deviation and other effects have been largely attributed to neglected viscoelastic effects [45],... 

Let us consider another example in order to emphasise the extraordinary importance of the dilational elasticity for the understanding of the adsorption state of surfactant molecules. The experimental values of the viscoelasticity for two homologues of alkyl dimethyl phosphine oxides (C 4 and Cio) measured using the oscillating bubble method [96] are presented in Fig. 2.12. The existence of the maxima in the experimental curves are due to the finite magnitude of the oscillations of the bubble surface (-10%) resulting in an over-saturation of the surface layer at higher surfactant concentrations in the bulk phase and at the interface. 

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