Structural characteristics of aramid fibre variants

Dobb, M. G.; Robson, R. M.

doi:10.1007/bf00714056

Cited by 103 publications

(50 citation statements)

References 4 publications

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“…The dark regions shown in Figure 28 are locations of microvoids in Kevlar 29 stained by silver sulphide (Ag 2 S). The reduction in the SAXS intensity notified the presence of moisture in the voids [57][58][59][60] . Grujicic et al 56,61 reported that the insertion of molecular nitrogen will cause voids.…”

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confidence: 99%

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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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mentioning

confidence: 99%

“…Voids affect the mechanical properties of the fibers, namely, they tend to decrease the tensile strength 58,59,131 . The PPTA fabrics capacity to absorb water and ability to take up dyestuff are very low compared to other fabrics 130 .…”

mentioning

confidence: 99%

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

et al. 2014

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“…The aramid fibers have been commercially available for nearly twenty years, and the excellent work in university laboratories, such as by Dobb et al at Leeds has continued [484,485]. New types of aramid fibers have been studied to compare the tensile behavior and the structure, by electron microscopy and x-ray diffraction studies [484].…”

Section: Aromatic Polyamidesmentioning

confidence: 98%

“…New types of aramid fibers have been studied to compare the tensile behavior and the structure, by electron microscopy and x-ray diffraction studies [484]. SEM images, taken of fractured fiber surfaces, recovered after breaking in glycerol and cleaning in hot water, showed a range of internal defects in the fibers and further information was gained from ultrathin sections of fibers first impregnated with silver sulphide (Section 4.4.7) [486].…”

Section: Aromatic Polyamidesmentioning

confidence: 99%

Polymer applications

Sawyer¹,

Grubb²

1996

Polymer Microscopy

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“…TEM has been widely used to study the crystalline structure of high-strength and high-stiffness LCP fibres and other paracrystalline polymer structures (Sawyer, 1984;Dobb & Robson, 1990;Sawyer & Jaffe, 1991;Hu et al, 1992;Young et al, 1992). The analysis has revealed detailed and more localized information on the crystalline structure of aramid and thermotropic LCP fibres as well as the development of skin-core morphology in such fibres.…”

Section: Introductionmentioning

confidence: 99%

Structure and morphology of the in situ composites of a liquid crystalline polymer and polycarbonate

Xiao

Lin

Yee

et al. 1997

Journal of Microscopy

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SummaryIn situ composites were prepared via melt blending of a liquid crystalline polymer (LCP) and polycarbonate using a twin screw extruder. The structure and morphology of these composites were analysed using both transmission electron microscopy (TEM) and scanning electron microscopy. The LCP phases were able to orientate and form in situ submicrometre fibres during the extrusion and postextrusion drawing. TEM images as well as selected-area diffraction patterns were obtained from the materials. The effects of both composition, i.e. LCP content, and postextrusion draw-down ratio on the development of the in situ formed LCP fibres were studied in detail. A skin-core morphological differentiation is observed in these materials where well-defined LCP fibres of higher aspect ratios were formed in the skin region. However, a significant amount of unelongated LCP particles were found coexisting with the less well-defined fibres in the core region of the extrudates. This skin-core differentiation was found to be dependent on the composition and the processing conditions, e.g. draw ratio. In this instance, electron microscopy is proven to be a powerful technique not only for direct observation of the formation, dimensions and morphology of the in situ LCP fibres, but also for the qualitative and quantitative characterization of the molecular orientation and crystalline structures in these fibres using selected-area electron diffraction. It is observed that the skin-core differentiation becomes more distinct in the in situ composites containing a higher percentage of LCP but diminishes when the material is processed at higher post-extrusion draw ratio.

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Structural characteristics of aramid fibre variants

Cited by 103 publications

References 4 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

Polymer applications

Structure and morphology of the in situ composites of a liquid crystalline polymer and polycarbonate

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