relaxation processes of polar molecules in some organic glasses
abstract
dielectric absorption studies of a variety
of polar solutes containing rotatable groups and of
some analogous rigid molecules dispersed in (i) an
atactic polystyrene matrix, (ii) glassy o-terphenyl
and polyphenyl ether have been carried out. sample
preparations and the dielectric measurements using
general radio 1615-a and 1621 capacitance bridges with
appropriate temperature-controllable cells have been
described. the glass transition temperature measurements
using the glass transition temperature measurement
apparatus have also been described. the experimental
data as a function of frequency at different temperatures
were subject to analysis by a series of computer programmes
written in apl language. the activation energy barriers
opposing the dielectric relaxation processes were obtained
by the application of the eyring rate equation.
different types of polar rigid molecules have
been studied mainly to provide sources of relaxation data
and activation parameters in the three media for comparison
with those of flexible molecules of analogous size.
the results of these rigid molecules have been used
to obtain a correlation between enthalpy and entropy of
activation; enthalpy of activation and volume needed
for the reorientation of the rigid molecules. the
activation parameters for the rigid molecules were found
to depend on the nature of the solvent.
collections
- retrospective theses [1604]