A COMPARISON OF RELAXATION-TIME DISTRIBUTIONS OBTAINED FROM DYNAMIC LIGHT-SCATTERING AND DYNAMIC MECHANICAL MEASUREMENTS FOR HIGH-MOLECULAR-WEIGHT POLYSTYRENE IN ENTANGLED SOLUTIONS

The purpose of this work was to examine possible similarities between the relaxation time distributions for polystyrene in semidilute solutions in the θ solvent bis(2-ethylhexyl) phthalate (dioctyl phthalate, DOP) obtained from dynamic light scattering (DLS) and dynamic mechanical (DM) measurements. The paper deals mainly with the influence of concentration and molecular weight but also with the role of solvent quality through change in temperature. The DLS and DM relaxation functions have been analyzed by inverse Laplace transformation (ILT) and the DLS data also by fitting the slow, q-independent, part of the spectrum to a general exponential function. It was found that with both techniques the dynamical processes probed at long times are characterized by a similar wide range of relaxation times and that the latter increases strongly with concentration and molecular weight. However, the distribution of relaxation times from DLS is much more sensitive in the slow part of the spectrum to changes in solvent quality. © 1990, American Chemical Society. All rights reserved.