Peek Oligomers - a Model for the Polymer Physical Behavior .3. Nature of Oligomers in the Peek Polymer
(1993) Macromolecules — Vol. 26, n° 11, p. 2674-2678 (1993)
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- Low molecular weight compounds extracted from PEEK have been identified by C-13 NMR, infrared spectroscopy, and size-exclusion chromatography as being cyclic PEEK oligomers. The molecular weight of these cyclic oligomers is larger than 1000. Their wide-angle X-ray scattering powder pattern and crystal habit are totally different from those of the polymer. DSC experiments reveal that the oligomers crystallize in two different crystal types. The nucleation rate of these crystals is rather slow because of the large size of the molecules which have to be incorporated in the nucleus. Consequently, moderate cooling rates give rise to glassy oligomers. A very high T(g) value is observed for the oligomers, in accordance with their low configurational entropy in the amorphous state due to their cyclic structure.
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Jonas, A., & Legras, R. (1993). Peek Oligomers - a Model for the Polymer Physical Behavior .3. Nature of Oligomers in the Peek Polymer. Macromolecules, 26(11), 2674-2678. https://doi.org/10.1021/ma00063a005 (Original work published 1993)