ISSN:
0025-116X
Schlagwort(e):
Chemistry
;
Polymer and Materials Science
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Physik
Notizen:
Rapid scanning Fourier transform infra-red spectroscopy was used to follow the changes in the population of trans conformers and in the infra-red dichroic functions of the bands characterizing the trans (T) and gauche (G) conformers and the chains in the amorphous regions during stretching of a solution-cast amorphous poly(ethylene terephthalate) (PET) film A in the glassy state (67°C) and in the rubbery state (88°C). Stretching at 67°C showed a yield stress peak followed by strain softening in the stress-strain curve. The population of trans conformers in the amorphous and crystalline regions, Ta + Tc, decreased in the pre-yielding region and then increased continuously after yielding. The T conformers formed during post-yield stretching showed high orientation, while the G conformers remained in low degree of orientation. Stretching at 88°C showed no pronounced yield stress peak in the stress-strain curve, and the population of T conformers did not change until the beginning strain-induced crystallization. A solvent-cast PET film annealed at 67°C for 24 h, the film N, showed a sharp and high yield stress peak in the stress-strain curve, and strain-induced crystallization occurred at lower draw ratio as compared to the film A. The film A showed a non-equilibrium high population of Ta conformers, part of which reverted to G conformers during sub-Tg annealing.
Zusätzliches Material:
4 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/macp.1991.021920212
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