Av. Veniaminov et Yn. Sedunov, DIFFUSION OF PHENANTHRENEQUINONE IN POLY( METHYL METHACRYLATE) - HOLOGRAPHIC MEASUREMENTS, Vysokomolekularnye soedinenia. Seria A, 38(1), 1996, pp. 71-76
The diffusion coefficient of phenanthrenequinone in PMMA was measured
in the temperature range extending over glassy, rubberlike, and fluid
viscous states of the polymer. The measurement method was based on rec
ording the time changes in the optical characteristics of holographic
gratings photoinduced in the bulk of a sample under investigation. For
temperatures below 140 degrees C, the data were extracted from the dy
namics of diffraction efficiency of the gratings, whereas for higher t
emperatures, the data were obtained from diffusion-induced changes of
angular selectivity contour. The diffusion coefficient varied from 10(
-21) to 10(-11) m(2)/s. Its temperature dependence showed inflections
corresponding to the polymer transitions from one state to another. Th
e apparent activation energies and parameters of the Williams-Landel-F
erry equation were also calculated.