DIFFUSION OF LARGE PENETRANT MOLECULES IN AMORPHOUS POLYMERS

A new version of the free-volume theory of diffusion is modified to describe self-diffusion phenomena in polymer plus solvent systems for solvents which do not move as single units. The free-volume equations are used to interpret data which appear to illustrate that some large solvent molecules do indeed move in a segmentwise manner. The dependence of the effective activation energy for diffusion on solvent size is examined, and the importance of energy effects on the diffusion process is considered.