SELF-DIFFUSION AND MUTUAL-DIFFUSION COEFFICIENTS IN THE DODECANE POLYSTYRENE SYSTEM

The self-diffusion coefficient of dodecane in cross-linked polystyrene was measured using pulsed gradient spin echo nuclear magnetic resonan ce (PGSE-NMR) spectroscopy. The concentration and temperature dependen ce of the diffusion coefficient was analyzed by the Fujita and Vrentas -Duda models. Parameters describing the Fujita model were determined f rom fitting of diffusion data to the PVT behavior of the system. Param eters describing the Vrentas-Duda model were determined from the analy sis of the viscosity of dodecane, the viscoelastic relaxation properti es, and the glass transition temperature of polystyrene as well as fro m the diffusion coefficient of the system, measured from independent e xperiments. Both the Fujita and Vrentas-Duda models described well the concentration and temperature dependence of the diffusion coefficient . Mutual diffusion coefficients were determined from these results. (C ) 1994 John Wiley & Sons, Inc.