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The fractionation of a statistical copolyester made of poly(ethy1ene terephthalate-isophthalate) has been performed using Temperature Rising Elution Fractionation (TREF). TREF fractions were analyzed by size exclusion chromatography, thermal analysis, 'H-nuclear magnetic resonance and small angle X-Ray diffractometry. Results show that the fractions exhibit both interchain and intrachain defect distribution. As the intrachain defect distribution can not be determined by experimental techniques, a computer simulation based on the determination of terephthalic sequences length in a virtual polymeric distribution was performed. The simulated chains were constructed using a stochastic process. The analysis of the results obtained on the distribution of the simulated sequences in the polymer correlates quantitatively well between the new fractionation mechanism proposed for copolyesters and the experimental results.

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The sulfonation kinetics of fluorine ended poly(ether ether ketone) (PEEK) in solution in 95.9% and 96.8% concentrated sulfuric acid was studied with the help of a model compound representative of the PEEK chain repeat unit. The reaction rate of the model compound sulfonation was found to be first order with respect to the aromatic ring to be sulfonated. Consequently, PEEK kinetic data were treated following a first order with respect to the unsulfonated repeat unit concentration. Two rate‐slowing effects were detected. They were attributed to ‘long range’ electronic effects resulting from the inductive nature of the fluorine atom, and from the electron‐withdrawing character of the grafted sulfonic acid group.© 2001 Society of Chemical Industry