DIFFUSION OF PHENANTHRENEQUINONE IN POLY( METHYL METHACRYLATE) - HOLOGRAPHIC MEASUREMENTS

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.