TRACER DIFFUSION OF LINEAR POLYSTYRENE IN ENTANGLEMENT NETWORKS

The tracer diffusion coefficient Dtr∞ of linear polystyrenes (PS) with weight-average molecular weights Mw from 6100 to 2 890 000 was measured in entanglement networks of PS with Mws much higher than the molecular weight of the respective diffusants at temperature of 30 °C by using forced Rayleigh scattering technique. Total polymer concentration C was 13 and 18 wt %, and C of the diffusant was fixed at 1 wt %. Dibutyl phthalate was used as solvent. Dtr∞ data at C = 13 and 18 wt % and also those obtained at 40.6 wt % in an earlier study were found to be superposed on one master curve by using two parameters, an effective friction coefficient of a segment ξ and the molecular weight between entanglements Me, for reduction. Reduced Dtr∞ was proportional to M-1 and M-2.5 in the unentangled (M/MD < 1) and the entangled region (M/MD > 1), respectively, where MD is the molecular weight at the intersection point and is very close to Me. © 1990, American Chemical Society. All rights reserved.