A generalized method to calculate diffusion rates in polydisperse systems.Further results on Rouse dynamics in the concentrated regime

Experiments designed to thoroughly test a recently proposed generalized met hod to calculate diffusion rates in polydisperse systems have been carried out. Polydisperse polystyrene (PS) samples were allowed to diffuse in a pol y(phenylene oxide) (PPO) matrix. Designed blends were made from anionically polymerized PS with molecular weights which cover most of the ranges where Rouse dynamics control the diffusion processes. The diffusion temperatures range from (T-g - 1 K) to (T-g + 105 K), causing the monomeric friction fa ctor values for PS to change by up to seven orders of magnitude along the d iffusion coordinate. Calculations performed with the above mentioned method agree with Raman and DMA experimental data.