Determination of molecular orientation in poly(ethylene terephthalate) by means of 2H nuclear magnetic resonance

Röber, S.; Zachmann, H. G.

doi:10.1016/0032-3861(92)90872-t

Cited by 19 publications

(5 citation statements)

References 11 publications

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“…From the carboxyl pattern, the out-of-plane distribution of carboxyl group ZP axes was determined to be 35 f 5'. As an even more powerful possibility (discussed above), 3D DECODER NMR provides in principle an avenue to the full three-dimensional distributionP(@, 6,9) of molecular segments in the sample.…”

Section: In-plane Distribution Of Chain Axes Zmmentioning

confidence: 99%

Molecular orientation distributions in poly(ethylene terephthalate) thin films and fibers from multidimensional DECODER NMR spectroscopy

1993

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Multidimensional DECODER NMR experiments are applied to several industrial samples of poly(ethy1ene terephthalate) (PET) thin films and fibers, exploiting natural-abundance 13C resonances from different carbon sites to quantify orientational order in these materials. In two-dimensional (2D) DECODER NMR, the sample is flipped through a discrete angle during the mixing time of a 2D exchange NMR experiment. This allows frequencies at two spatial orientations to be correlated to elucidate molecular order in the sample. The theoretical background needed to analyze the corresponding 2D pattern in terms of angular distributions is outlined, and reconstruction of relevant one-dimensional slices through the orientation distribution is demonstrated. In PET fibers, direct reconstruction produces an orientation distribution that is at least bimodal; 60% of the chains are highly oriented, with a full-width-at-half-maximum (fwhm) of 20". The angle between the phenylene para axis and the fiber axis is determined to be 18 * 4". For biaxially drawn films, the direct reconstruction of slices through the orientation distribution shows that in a highly oriented fraction (ca. 80%) of the sample, the chain axes are confined to the film plane (fwhm of 15"), while the in-plane distribution of chain axes is much broader (fwhm of ca. SO"); the phenylene rings and carboxyl group planes are oriented preferentially parallel to the plane of the film (fwhm of 55"). Film samples collected at different points across an industrial sheet of PET are shown to exhibit sizable variations in ordering. For the center of the sheet, a slight preferential orientation along the transverse direction is clearly detected. Increased alignment of the PET chains (fwhm of 557, with the preferred orientation rotated toward the machine direction, is observed near the sheet edge. In uniaxial films, the fwhm of the orientation distribution is measured to be 85". A 3D DECODER experiment is implemented to separate frequency patterns that overlap in two dimensions.

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Section: In-plane Distribution Of Chain Axes Zmmentioning

confidence: 99%

Molecular orientation distributions in poly(ethylene terephthalate) thin films and fibers from multidimensional DECODER NMR spectroscopy

1993

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“…Reflecting the importance of the semicrystalline polymer poly(ethylene terephthalate) PET, considerable scientific effort has been made to elucidate its properties. The research in connection with PET covers virtually all aspects of polymer physics such as correlation between X-ray structure and force field methods, , dielectric measurements , and their relation to mode coupling theory, crystal structure, the relation between morphology and mechanical properties, − or the characterization of orientation. , Important aspects can be studied by the use of solid-state NMR spectroscopy to determine morphology, , orientation, − and mobility − in the bulk material. Previous solid-state NMR studies concerning mobility were restricted to information deduced from relaxation times or line shape analysis.…”

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Detection of Slow 180° Phenylene Flips in PET Fibers via ¹³C Two-Dimensional Solid-State Exchange NMR

Wilhelm

Spieß

1996

Macromolecules

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“…Crystalline and amorphous IR-patterns for this band have been reported earlier [6]. In NMR studies associates of phenylene rings in the amorphous regions of PET have been detected [22]. But since there is no hard evidence that associates have been found in more extensive IR studies, it is not certain that this extra peak is assigned to benzene associates.…”

Section: Peak Detection On Series Using Two-dimensional Couariance Camentioning

confidence: 58%

Spectral curve fitting of infrared spectra obtained from semi-crystalline polyester yarns

Weijer

Buydens

Kateman

et al. 1995

Chemometrics and Intelligent Laboratory Systems

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Please be advised that this information was generated on 2018-05-09 and may be subject to change. Chemometrics and intelligent laboratory systems ELSEVIERInfrared spectra of polymer yarns exhibit a large number of strongly overlapping peaks. One of the methods to study the physical yarn structure quantitatively is to resolve the spectra into separate bell-shaped peaks. Due to the overlapping peak patterns, curve fitting with steepest descent like procedures depend on accurate initial estimates of the peak parameters. We developed a non-local curve fitting procedure, based on a genetic algorithm, which proved to be less sensitive to initial estimates. The combination of a genetic algorithm with a nonlinear estimator, based on Marquardt's method, gave the best curve fitting results. Chemometrics and Intelligent Laboratory Systems 28 (1995) 149-164Spectral curve fitting of infrared spectra obtained from semi-crystalline polyester yarns Abstract -

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Determination of molecular orientation in poly(ethylene terephthalate) by means of 2H nuclear magnetic resonance

Cited by 19 publications

References 11 publications

Molecular orientation distributions in poly(ethylene terephthalate) thin films and fibers from multidimensional DECODER NMR spectroscopy

Molecular orientation distributions in poly(ethylene terephthalate) thin films and fibers from multidimensional DECODER NMR spectroscopy

Detection of Slow 180° Phenylene Flips in PET Fibers via ¹³C Two-Dimensional Solid-State Exchange NMR

Spectral curve fitting of infrared spectra obtained from semi-crystalline polyester yarns

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Determination of molecular orientation in poly(ethylene terephthalate) by means of 2H nuclear magnetic resonance

Cited by 19 publications

References 11 publications

Molecular orientation distributions in poly(ethylene terephthalate) thin films and fibers from multidimensional DECODER NMR spectroscopy

Molecular orientation distributions in poly(ethylene terephthalate) thin films and fibers from multidimensional DECODER NMR spectroscopy

Detection of Slow 180° Phenylene Flips in PET Fibers via 13C Two-Dimensional Solid-State Exchange NMR

Spectral curve fitting of infrared spectra obtained from semi-crystalline polyester yarns

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Product

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Detection of Slow 180° Phenylene Flips in PET Fibers via ¹³C Two-Dimensional Solid-State Exchange NMR