Characterization of elastomers with transverse sonic waves

Transverse sonic waves in the frequency regime of typically 0.5-5 kHz have been employed for the mechanical characterization of elastomers. Whereas the degree of polymerization has an almost negligible influence on the velocity of longitudinal polarized sound, the velocity of transverse polarized sound is substantially influenced by the polymerization. Major difficulties involved in measurements of transversal waves in elastomers arise from the extremely high damping present in these materials with Poisson ratios near 0.5. The sonic excitation and detection schemes presented here are based on specially developed compound transducers, avoiding distortions of the transit signals for transversal polarized sound by the nearly undamped and much faster propagating longitudinal polarized sound. Applications including on- and off-line characterizations are demonstrated for a variety of technically relevant elastomers and for curing materials.