화학공학소재연구정보센터
Journal of Physical Chemistry, Vol.99, No.34, 12962-12970, 1995
Equilibrium and Dynamic Dielectric-Properties of Acrylate Polymers with (Phenyl)(4-Chlorophenyl)Methanone Groups in Their Structure
The curves describing the relaxation behavior of poly(4-(acryloxy)phenyl) (4-chlorophenyl)methanone at several frequencies present in the dielectric loss-temperature plane a beta relaxation centered at -76 degrees C at 10 Hz, whose activation energy shows a slight tendency to increase as the temperature goes up. The relaxation spectra exhibit an ostensible glass-rubber relaxation or a process centered at 106 degrees C at 10 Hz, in which free charge conductivity and blocking electrode phenomena become dominant at frequencies below 10 Hz. An electric model is used to separate the dipolar response from conductivity contributions in the glass-rubber relaxation, and the dipole time correlation function for this process is obtained at several temperatures. The intramolecular correlation coefficient g(intra), determined from dielectric measurements in solution, is somewhat larger than the coefficient g involving both intra- and intermolecular interactions, obtained from dielectric measurements in the bulk. A rotational state scheme is developed which gives a good account of the intramolecular dipolar correlation coefficient. Finally whereas the relaxation mechanisms involved in the glass-rubber relaxation seem to be governed by the volume, the conductive processes exhibit Arrhenius behavior.