Longitudinal and shear mechanical relaxation data are reported for a hydration of 20% of synthetic diethylamine melanin. The longitudinal attenuations per wavelength αλ at frequencies between 1 and 5 MHz show an enormously large amount of absorption above room temperature. The amount αλ/2π=0.55–0.95 at a temperature of 60 °C in the frequency of 1 MHz has never been found in usual polymeric substances where αλ/2π∼0.1. The longitudinal data are interpreted in terms of a combined relaxation and resonance process. Measurements of the shear impedance in the temperature range from −10 to +60 °C, with frequencies ranging from 5.2 to 362 MHz, indicate a distribution of relaxation times, represented by the Davidson-Cole spectrum. Temperature dependency of limiting shear modulus is found to obey the Hirai-Eyring equation.

Shear and longitudinal relaxation data are reported for aqueous solution of 23 mole % ethanol. Measurement of shear impedance in the temperature range +20 to −40 °C and frequency range 8.6–740 MHz indicates a composite spectra of double or triple relaxation. Longitudinal data are measured by Brillouin scattering and pulse techniques in a frequency range from 20 MHz to 6 GHz. Complicated processes involved are interpreted in terms of additive contributions to longitudinal moduli, comprising (1) structural viscoelastic relaxation of the spectra employed in shear data; (2) a relaxation of concentration fluctuation with a modified form of Romanov and Solovyev.

Ultrasonic velocity data are reported for the ethanol-water mixture of 23 mole% at frequencies between I and 5 MHz in the temperature range from -80· to + 20' C. Velocities in a crystalline state are far lower than that of ice. The mixtures in the concentration ranging from 9.4 to 23 mole% ethanol indicate a maximum density in a saturated liquid state. The 23 mole% ethanol mixture. among others. grows into a layered hexagonal crystalline structure. Temperature dependency of limiting shear modulus is found to obey the Hirai-Eyring equation. deviating down at high temperatures. The deviation is interpreted in terms of the structural decay process due to the decomposition of the cluster containing 10-15 molecules.

Ultrasonic and hypersonic relaxation data are reported for a polymeric liquid oligobutene at frequencies between 51 kHz and 8 GHz in the temperature range from -60 to 100 'C. It is found that the superposition principle holds up to 0.76 GHz for shear data, while for the bulk process spectral narrowing takes place around 3 GHz. This difference can be interpreted in terms of a local theory presented by one of the authors.