Supermolecular structure and elastic properties of fibres prepaped from aromatic polyamides

Slutsker, L.I.; Chereiskii, Z. Yu.; Utevskii, L. E.; Kuz'min, V. N.; Kalmykova, V.D.; Соколова, Т. С.; Volokhina, A. V.; Kudryavtsev, G. I.

doi:10.1016/0032-3950(75)90188-4

Cited by 6 publications

(1 citation statement)

References 8 publications

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“…The angle between the two planar surfaces forming the pleated sheet structure is about 170° - Figure 21. Each pleat sheet has a misorientation angle of about 5°-7° to the fiber axis-this misorientation also applies to the crystallites forming a pleated sheet 13,45,52,54 .…”

Section: Pleat Sheet Structurementioning

confidence: 99%

Microstructural developments of poly (p-phenylene terephthalamide) fibers during heat treatment process: a review

et al. 2014

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Poly (p-phenylene terephthalamide) fibers prepared by wet or dry-jet wet spinning processes have a notable response to very brief heat treatment (seconds) under tension. The modulus of the as-spun fiber can be greatly affected by the heat treatment conditions (temperature, tension and duration). The crystallite orientation and the fiber modulus will increase by this short-term heating under tension. Poly (p-phenylene terephthalamide) fibers have a very high molecular orientation (orientation angle 12-20°). Kevlar  and Twaron  fibers are poly (p-phenylene terephthalamide) fibers. This review reports for PPTA fibers the heat treatment techniques, devices and its process conditions. It reports in details the structural relationships between the fiber properties which are influenced by the heat treatment process. In particular, focused deeply on the effect of the crystal structure and the morphology of the fibers on the mechanical properties of PPTA fibers.

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Section: Pleat Sheet Structurementioning

confidence: 99%

Microstructural developments of poly (p-phenylene terephthalamide) fibers during heat treatment process: a review

et al. 2014

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Morphology of poly(p‐phenylene terephthalamide) fibers

Panar¹,

Avakian²,

Blume³

et al. 1983

J. Polym. Sci. Polym. Phys. Ed.

222

142

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Fibers of poly(p‐phenylene terephthalamide) (PPTA) have a fibrillar morphology, the individual fibrils having a high proportion of extended chains passing through periodic defect layers. A pleat structure is superimposed. The fibers are fully crystalline (within the limits of determination) with a small fraction of randomly oriented crystalline material. The major distinction between PPTA and conventional fibers lies in the high level of extended chains passing through the defect layers of the former structure. These extended chains result in crystallographic register being maintained between adjacent ordered zones. Quantitatively, a measure of this order is obtained from a comparison of the correlation length, obtained from meridional x‐ray peak widths, and the defect spacing. In conventional fibers the defect spacing, i.e., long period, is longer than the correlation length (i.e., crystal size). In PPTA, the analog of the long period, the defect spacing (about 35 nm) is smaller than the correlation length, which is over 80 nm.

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Polymer fibers drawn to the limit

Slutsker¹,

Utevskii

1984

J. Polym. Sci. Polym. Phys. Ed.

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The orientational drawing of polymers is known to be terminated because of sample rupture. The limiting draw ratio λlim reached may be different (either large or small) depending on the polymer and the actual drawing conditions. The purpose of the present work is to identify the change of supermolecular structure of polymer fibers which results in the termination of orientational drawing. Small‐and wide‐angle x‐ray diffraction were used to study the variation of geometrical parameters of this structure with increasing draw ratio λ. The geometrical parameters discussed are the dispersions (fluctuation) of long periods and of longitudinal sizes of crystalline as well as amorphous regions. In this study we used fibers of poly(vinyl alcohol), poly(ε‐caprolactam), polyoxymethylene, and poly(4,4′‐diphenyloxide) pyromellitimide. It is found that the long period dispersion of these polymers, drawn under different conditions, increases to approximately the same value for different samples drawn to the limit, this relative standard deviation δL of long periods being 0.30‐0.40. It is also found that the crystallite size dispersion does not increase with increasing λ; the increase of λL is due to increasing dispersion of the amorphous region lengths. For poly(vinyl alcohol) fibers drawn to the limit under different conditions and which have different λlim, the relative standard deviation of the sizes of amorphous regions δA turned out to be about the same (ca. 0.60). The latter evidence gives grounds to suggest that the rupture of polymers under drawing is associated with reaching a high degree of amorphous region size dispersion. In those regions which are considerably below the average size there probably will appear local overstress and molecular ruptures because the relative deformation of these regions is much larger than that of the adjacent regions in the cross section of the sample.

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Supermolecular structure and elastic properties of fibres prepaped from aromatic polyamides

Cited by 6 publications

References 8 publications

Microstructural developments of poly (p-phenylene terephthalamide) fibers during heat treatment process: a review

Microstructural developments of poly (p-phenylene terephthalamide) fibers during heat treatment process: a review

Morphology of poly(p‐phenylene terephthalamide) fibers

Polymer fibers drawn to the limit

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