Summary
The morphology of extended chain lamellae and fibrous polytetrafluoroethylene has been analyzed by electron microscopy and compared to polyethylene. The crystal growth mechanism of initial folding on molecular nucleation followed by chain extension is applicable to both polymers and seems to be a general mechanism for crystallization of prepolymerized linear macromolecules. Differences arise from the branching mechanism of the spherulites. Annealing the striated surface created on fracture could be shown to lead to folded chain “ripples” of time and temperature dependent thickness. Fibrous crystals of smooth and shish-kebob-type appearance were grown from gaseous tetrafluoroethylene.
Zusammenfassung
Die Morphologie der „extended chain“-Lamellen und von faserigem Polytetrafluoräthylen wird elektronenmikroskopisch analysiert und mit Polyäthylen verglichen. Der Kristallwachstumsmechanismus anfänglicher Faltung bei molekularer Nukleation, gefolgt von Streckung der Ketten, kann auf beide Polymere angewendet werden und scheint ein allgemeiner Mechanismus der Kristallisation von polymerisierten linearen Makromolekülen zu sein. Unterschiede entstehen vom Verzweigungsmechanismus bei den Sphärolithen. Tempern der gestreiften Bruchflächen — so ließ sich zeigen-führt zu „Riffeln“ von gefalteten Ketten mit zeit- und temperaturabhängigen Dicken. Faserige Kristalle vom glatten und vom Schaschlik-Typ wachsen von gasförmigem Polytetrafluoräthylen.
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Dedicated to ProfessorR. Hosemann on the occasion of his 60th birthday.
For part I–VI of this series see J. Polymer Sci., Part A2, 2043–2113 (1969), Part VII, J. Polymer Sci., Part B,10, 57 (1972).
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Melillo, L., Wunderlich, B. Extended-chain crystals. Kolloid-Z.u.Z.Polymere 250, 417–425 (1972). https://doi.org/10.1007/BF01507508
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DOI: https://doi.org/10.1007/BF01507508