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Digitale Medien

On the dynamic mechanical behaviour of drawn poly(ethylene terephthalate) fibers (1968)

Dumbleton, J. H. ; Murayama, T. ; Bell, J. P.

Springer

Colloid & polymer science 228 (1968), S. 54-58

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ISSN: 1435-1536

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie , Maschinenbau

Beschreibung / Inhaltsverzeichnis: Zusammenfassung Der Einfluß von Verstreckung und Temperaturbehandlung auf den α-Übergang in Poly(äthylenterephthalat), PET, Garn wurde untersucht unter Anwendung von Röntgen- und dynamisch-mechanischen Methoden. Es wurde gefunden, daß für hohe Vergütungstemperaturen verstreckte, kristalline PET-Garne eine Verschiebung des α-Überganges zu niedrigeren Temperaturen aufweisen, ähnlich wie für nicht verstrecktes, kristallines PET. Der Hauptunterschied zwischen verstreckten und nicht verstreckten Garnen ist die Lage des α-Überganges auf der Temperaturskala; der α-Übergang liegt für höhere Verstreckung bei höheren Temperaturen. Die Verlagerung des α-Überganges durch Temperaturbehandlung wird auf die Anzahl der Kristallite zurückgeführt, während seine Verschiebung durch Verstreckung erklärt wird durch die Orientierung in den amorphen Bezirken.

Notizen: Abstract The effect of drawing and annealing treatments on the α transition in poly(ethylene terephthalate), PET, yarns has been studied using a combination of X-ray and dynamic mechanical techniques. It was found that drawn, crystalline PET yarns exhibit a shift in the position of the α transition to lower temperatures for high annealing temperatures; this effect has been observed for unoriented, crystalline PET. The main difference between the results for the drawn and unoriented yarns lies in the position of the α transition on the temperature scale; the α transition occurs at higher temperatures the higher the draw ratio. The shift in the position of the α transition with anealing is interpreted in terms of the number of crystals whilst the change in position of the α transition brought about by drawing is explained by orientation in the amorphous regions.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02125764

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Digitale Medien

Relation between melting behavior and physical structure in polymers (1969)

Bell, J. P. ; Dumbleton, J. H.

New York : Wiley-Blackwell

Journal of Polymer Science Part A-2: Polymer Physics 7 (1969), S. 1033-1057

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ISSN: 0449-2978

Schlagwort(e): Physics ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Notizen: The phenomenon of double melting, as manifested by two characteristic endotherms in the melting region on a differential thermal analysis (DTA) scan, has been studied in nylon 66 and polystyrene as a function of sample treatment by annealing or drawing. A variety of techniques were used in these studies including DTA, x-ray diffraction, electron microscopy, and mechanical testing. It is shown that the two endotherms are not caused by a bimodal crystal size distribution, by recrystallization, by orientation changes, or by phase changes. It is proposed that one endotherm is caused by the melting of foldedchain crystals, while the other is due to the melting of less perfect bundle crystals. This view is well supported by the results, especially by the DTA measurements made at different heating rates. Published data on the thermal behavior of annealed and drawn poly(ethylene terephthalate) and on polyethylene crystallized at various pressures may also be explained on this basis if it is allowed that in polyethylene the chains may be more extended.

Zusätzliches Material: 15 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pol.1969.160070606

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Digitale Medien

Multiple melting in nylon 66 (1968)

Bell, J. P. ; Slade, P. E. ; Dumbleton, J. H.

New York : Wiley-Blackwell

Journal of Polymer Science Part A-2: Polymer Physics 6 (1968), S. 1773-1781

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ISSN: 0449-2978

Schlagwort(e): Physics ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Physik

Notizen: Either of the two endothermic melting peaks found by differential thermal analysis of nylon 66 may be converted to the other by appropriate choice of annealing conditions. The two peaks are considered due to the melting of two morphological species, forms I and II. Form I is relatively fixed in melting temperature, while the form II melting temperature varies with annealing conditions and can be either above or below form I. The two forms can be distinguished by whether or not the conversion I → II takes place; if the sample is in form II no change in the thermogram is observed under suitable conversion conditions. The conversion of form I to form II also takes place during cold drawing. It has been previously shown that form I results from rapid cooling from the melt, and form II results from slow cooling. Form I appears to be kinetically favored, while form II is thermodynamically preferred. The variability in the form II melting point is attributed to variable crystal size and/or perfection.

Zusätzliches Material: 9 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/pol.1968.160061007

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Digitale Medien

The effect of structural changes on dye diffusion in poly(ethylene terephthalate) (1968)

Dumbleton, J. H. ; Bell, J. P. ; Murayama, T.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 12 (1968), S. 2491-2508

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: The diffusion of a disperse dye, 1-amino-4-hydroxyanthraquinone (C.I. Disperse Red 15) into poly(ethylene terephthalate) fibers has been studied as a function of heatsetting temperature and draw ratio. It was found that the dynamic loss modulus E″, measured under the dyeing conditions, was related to the dye diffusivity D. This indicates that the diffusion is controlled by the mobility of the polymer chain segments. Both the diffusivity and dye saturation values do not vary monotonically with heatsetting temperature but exhibit a minimum at a heat-setting temperature near 175°C. X-ray diffraction measurements were used to show that this behavior is attributable to crystallinity and crystal size changes resulting from heat-setting.

Zusätzliches Material: 10 Ill.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1002/app.1968.070121109

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