Sorption and diffusion of carbon dioxide were measured in amorphous an
d crystalline poly(aryl-ether-ether-ketone) or PEEK, at different temp
eratures. The sorption follows Henry's law at all the investigated tem
peratures, and the reduction of sorption in the crystalline sample cor
responds to the reduction of the amorphous phase as derived from X-ray
s. Due to a more tortuous path, the diffusion parameter in the crystal
line sample is lower than in the amorphous one, whereas the activation
energy of the diffusion process is similar for both the samples. The
permeability to carbon dioxide was very low, comparable, or lower than
other rigid polymers. (C) 1994 John Wiley & Sons, Inc.