Solid-state morphology and mechanical properties of Kevlar 29 fiber

Hindeleh, A. M.; Halim, N. A.; Ziq, Kh. A.

doi:10.1080/00222348408219461

Cited by 48 publications

(19 citation statements)

References 5 publications

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“…In the case of Pn symmetry, however, the structural factor for the 001 reflection is not zero. (14,15,18,19,24). From these data, the average number paper, we will report on the WAXD study on the dehydration process using an as-spun wet PPTA fiber to detect the formation of the crystal lattice.…”

Section: Meridional Diffractionmentioning

confidence: 99%

Moisture Sorption Mechanism of Aromatic Polyamide Fibers. (Part 4). Effect of Water on the Crystal Structure of Regular Kevlar.

Fukuda

Kawai

1996

Sen-i Gakkaishi

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: Wide-angle X-ray diffraction studieswere performed for regular Kevlar under dried and wet conditions. The ratio of the diffracted intensity from the 110 crystal plane to that from the 200 crystal plane was reversibly changed from 0.92 at dryness to 0.74 at wetness. The 001 diffraction was detectable both in the dried and wet specimens. The longitudinal size of the paracrystallite, Door, also reversibly changed to about 1.3 times larger at dryness than at wetness, but the lattice distortion factor, go. evaluated by Hosemann's paracrystalline equation was kept nearly constant. The difference in the second order moments of the uniaxial orientation was only slight between the dried and wet specimens, but more complete orientation was detected in the dried specimen. These results suggested that the sorbed water penetrated the interstitial noncrystalline regions between the crystallites and may interfere with the hydrogen bonds of the outermost molecular chains which resulted in the distortion of the molecular packing both in the hydrogen bond direction and in the fiber axis.

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Section: Meridional Diffractionmentioning

confidence: 99%

Moisture Sorption Mechanism of Aromatic Polyamide Fibers. (Part 4). Effect of Water on the Crystal Structure of Regular Kevlar.

Fukuda

Kawai

1996

Sen-i Gakkaishi

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“…The defects in the crystal lattice can be improved by the possibility of lateral crystal growth (Axial crystal size) particularly along the hydrogen bonding direction occurring during the heat treatment of the PPTA fiber. The level of the distortion parameter of the paracrystallinity and the constant α* can be modified by the heat treatment as had been concluded by Hindeleh and Hosemann 122 and Hindeleh et al 44,123 . Lee reported that the distortion of the lattice decreases as the modulus increases during the fiber heat treatment process under tension.…”

Section: Axial Crystal Size (L)mentioning

confidence: 99%

“…On the other hand, the meridional scan gave peaks at diffraction angle 2θ of 6.9° for the (001), 13.7° for the (002), 27.1° for the (004) and 42° for the (006) Figure 11. WAXD patterns of Kevlar fibers, (up) Kevlar 29 44 , and (down) Kevlar 49 [41] . Figure 15 40 .…”

mentioning

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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“…The presence of voids in fibres can be demonstrated by electron microscopy, density measurements or small-angle X-ray scattering (SAXS). The latter technique was used for cellulose fibres [3][4][5][6], carbon fibres [7][8][9][10][11] and poly(p-phenylene terephthalamide) fibres [12,13]. The morphology of these fibres consists of not too closely packed fibrillar structures elongated in the fibre axis direction, and the voids are therefore also elongated in the same direction.…”

Section: Introductionmentioning

confidence: 99%

SAXS experiments on voids in gel-spun polyethylene fibres

1990

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The morphology and properties of extracted gel-spun polyethylene fibres depend on the spinning conditions. The main structures in the extracted fibre are shish-kebabs and lamellae. Equatorial small-angle X-ray scattering (SAXS) experiments show that the former structure is very porous due to the presence of lamellar overgrowth preventing a close package of the backbone fibrils, whereas the latter structure is relatively dense. After hot-drawing, due to melting/recrystallization, both structures are transformed on a 100 nm scale into a dense structure consisting of shish-kebabs or fibrils containing a void volume fraction of about 1%, as revealed by the scattering power of equatorial SAXS experiments. Moreover, a slight decrease of the equatorial intensity especially at the smallest angles after treating the hot-drawn fibres with paraffin oil, points to a small contribution of multiple scattering to the equatorial scattering. This implies the presence of a superstructure of not too closely packed macrofibrils. SAXS measurements of strained ultra-high-strength polyethylene fibres show that no or very little void formation is involved in the fracture mechanism. Most probably this is due to the (partly) fibrillar structure.

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Solid-state morphology and mechanical properties of Kevlar 29 fiber

Cited by 48 publications

References 5 publications

Moisture Sorption Mechanism of Aromatic Polyamide Fibers. (Part 4). Effect of Water on the Crystal Structure of Regular Kevlar.

Moisture Sorption Mechanism of Aromatic Polyamide Fibers. (Part 4). Effect of Water on the Crystal Structure of Regular Kevlar.

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

SAXS experiments on voids in gel-spun polyethylene fibres

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