ANOMALOUS ABSORPTION AND DISPERSION OF SOUND-WAVES IN DIETHYLAMINE MELANIN

被引:14
作者
KONO, R [1 ]
YAMAOKA, T [1 ]
YOSHIZAKI, H [1 ]
MCGINNESS, J [1 ]
机构
[1] UNIV TEXAS SYST,CTR CANC,DEPT PHYS,HOUSTON,TX 77030
关键词
D O I
10.1063/1.326143
中图分类号
O59 [应用物理学];
学科分类号
摘要
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.
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页码:1236 / 1244
页数:9
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