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 intrinsic properties of a yarn are brought about by its physical structure. This structure in its turn is controlled by the process conditions applied. A quantitative description is given of the effect of temperature, time, and tension during annealing on the structure of poly(ethylene terephthalate) yarns. Annealing of a yarn at elevated temperature leads to improvement of packing of the molecules within the crystals. Consequently, the crystalline density is not a constant but is largely dependent on the conditions under which crystallization has taken place. The growth of the PET crystals is not an isotropic process; the strongest growth is observed in the direction of the dipole interactions. The effects of tension and annealing time are also discussed. A prolonged annealing time causes an increase in crystallinity, while time and tension influence the growth of the crystals to some extent. However, for the experimental conditions used in this investigation, temperature is by far the most important factor. Generally speaking, PET fibers annealed at low temperature show low crystallinity built up of many small crystals. Yarn annealed at a high temperature, on the other hand, is composed of fewer big crystals together with large adjacent amorphous regions and relatively high overall crystallinity. Finally, the effect of this observed structural morphology on the dyeing behavior of PET yarns is discussed in a qualitative way. Two main effects controlling the dye uptake of PET yarn are proposed, viz., the total amount of amorphous regions and the accessibility of these regions.
Zusätzliches Material:
22 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/app.1978.070220407
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