Ultrasonic absorption in some homologous series of organic liquids

Summary

Part I. Results of ultrasonic absorption and velocity measurements in homologous series of fatty acids and alkyl acetates conducted over a range of frequency and temperature are reported. It is shown that the magnitude of the observed absorption and the relaxation frequency bear a relationship to the molecular weight in the series. It is also shown that the relaxation frequency in esters is the same for a common carboxyl group but depends on the molecular weight in a series of esters with different carboxyl radicals.Part II. Values of absorption coefficient and velocity in a number of saturated hydrocarbons — 1-olefines and aromatic hydrocarbons are reported. The relationship between the molecular weight on the one hand and the absorption coefficient and velocity together with their temperature coefficients on the other are discussed for the three series. It is suggested that while in the saturated and unsaturated aliphatic hydrocarbons the excess absorption is due partly to thermal relaxation and partly to bulk viscosity, in the case of aromatic hydrocarbons it is mainly due to thermal relaxation.

Riassunto

Gli Autori si sono proposti di dare un contributo alla interpretazione delle cause di assorbimento degli ultrasuoni nei liquidi, esaminando in particolare il problema dell’importanza relativa delle diverse cause di assorbimento (rilassamento termico, rilassamento strutturale, viscosità di volume; ecc.) in rapporto alla natura del liquido. A questo scopo essi hanno effettuato le loro determinazioni sperimentali su alcune serie omologhe di composti organici.