“…In an earlier study on isothermal crystallization of poly(aryl ether ketone ketone), Ezquerra et al 19 showed a very strong correlation between the strength of the dielectric relaxation, ⌬⑀ ϭ ⑀ 0 Ј Ϫ ⑀ ϱ Ј (where ⑀ ϱ Ј is the unrelaxed, highfrequency permittivity) and the crystallinity, as calculated from X-ray images. This and other studies 9,13,16,31,32 have shown that the extrapolation of crystallinity to ⌬⑀ ϭ 0 yields in some polymers a predicted crystallinity somewhat lower than 100%. However, we felt justified in using dielectric measurements to determine relative crystallization kinetics for our isothermally grown PDS films because this material typically crystallizes under good conditions to only about 40%.…”