Microwave Absorption and Molecular Structure in Liquids. LXXVII. Relaxation Mechanisms in Hexamethyldisiloxane and Hexaphenyldisiloxane

摘要

The dielectric relaxation processes in hexamethyldisiloxane have been investigated by measuring the dielectric constant and loss of the pure liquid at 2.1hyphen;mm wavelength and minus;thinsp;20deg;C and combining the results with those of previous measurements. Similar measurements have been made on a dilute solution of hexaphenyldisiloxane in carbon tetrachloride at 24deg; at wavelengths from 2.1 mm to 6thinsp;times;thinsp;106cm. The relaxation times calculated from these results confirm the existence of two relaxation processes in hexamethyldisiloxane, which are readily distinguished from each other at 0deg; and lower, but not at 20deg; and 40deg;. The magnitudes of the two relaxation times, together with those previously obtained for hexaethyldisiloxane, indicate that the longer relaxation process involves molecular rotation while the shorter involves bending, probably, amounting to inversion of the Sisngbnd;Osngbnd;Si group.