ORIENTATION RELAXATION IN GLASSY-POLYMERS .2. DIPOLE-SIZE SPECTROSCOPY AND SHORT-TIME KINETICS

The orientational diffusion of a rodlike particle embedded in a glassy polymeric matrix is considered; the underlying kinetics is that of lo cal rearrangements. A defining parameter of the theory is the length o f the particle. The timing of steps of the random walk in orientation space is determined by rearrangements. We discuss the physical propert ies of the glass state in connection with the rearrangement kinetics. The orientational diffusion is influenced by the local disorder; this influence is different for dipoles of different length. For a short di pole, the resulting diffusion is of generalized Debye type. Nonexponen tial relaxation of physical quantities may then be caused by the distr ibution of rearrangement barriers. For longer dipoles and if the orien tation is uniquely determined by the configuration of the embedding du ster, the motion is a random walk on a given random map on a sphere. A n ensemble of random mappings is considered. For even longer dipoles, hierarchical (multiscale) relaxation is expected. We discuss the relat ion of the theory to the shea time depoling kinetics in a system of di poles having different length, such as are found in relaxation of elec trically poled polymer materials. (C) 1995 American Institute of Physi cs.