Abstract
Experimental techniques to measure the viscoelastic mechanical properties of foamed elastomers at high frequencies were developed and applied to study foamed thermoplastic vulcanizates. The measurements were performed for foams with a wide range of void fractions such that a transition from a true porous solid to a foam was present. The frequency and time dependence of the dynamic and relaxation moduli, respectively, were measured and were shown to depend on the loss factor of the elastomer. The measured variation of the dynamic and the relaxation moduli with the void fraction did not depend on frequency and time in the frequency and time range of interest. This suggested that the time and frequency dependence of elastic moduli was determined mostly by the void fraction and the corresponding material microstructure. Property measurement results were compared to predictions for porous solids using the Mori-Tanaka method as well as methods for cellular solids.