SOLVENT ROTATIONAL MOBILITY IN POLYSTYRENE AROCLOR AND POLYBUTADIENE AROCLOR SOLUTIONS .2. A PHOTON-CORRELATION SPECTROSCOPIC STUDY

Dynamic depolarized light scattering has been utilized to probe the rotational motion of the solvent Aroclor (A1248) in solutions containing either polystyrene (PS) (C(PS) = 0, 0.086 or 0.146 g/cc) or 1,4-polybutadiene (PB) (C(PB) = 0.062, 0.098, or 0.16 g/cc) near the solution glass transition. The orientational time correlation functions C(VH) (t) for the solvent A1248 were recorded as a function of temperature (- 13 to - 31-degrees-C) over the time range 10(-6)-1 s by photon correlation spectroscopy. A unimodal relaxation time distribution describes C(VH) (t) at temperatures near T(g) and the breadth of the distribution of solvent relaxation time increases upon addition of the polymer. The average orientation time <tau> increases in PS/A1248 solutions and decreases in 1,4 PB/A1248 solutions, and the influence of 1,4 PB is temperature dependent. These main experimental results, which provide further support for the notion of polymer-induced modification to the solvent dynamics, are discussed in terms of the Adam-Gibbs description modified according to the coupling relaxation model.