Morphology and Structure of Kevlar Fibers: A Review

Chatzi, E. G.; Koenig, Jack L.

doi:10.1080/03602558708071938

Cited by 97 publications

(64 citation statements)

References 43 publications

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“…Frankland and coworkers employed the rule of mixtures analysis to estimate longitudinal elastic modulus of polymer nanotube composites [30]. Electron microscopy images identify heterogeneous structure of fiber composed highly oriented PPTA chains and amorphous PPTA regions [2,16]. Defects in the crystalline region plays crucial role in the determination of tensile modulus of fiber.…”

Section: Fiber Modulus Of Pptamentioning

confidence: 99%

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Modeling failure mechanisms of poly(p-phenylene terephthalamide) fiber using reactive potentials

Yılmaz

2015

Computational Materials Science

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Section: Fiber Modulus Of Pptamentioning

confidence: 99%

“…However experimental reports suggest skin-core structure for Kevlar Ò fibers [2,16]. Although PPTA fibers are highly crystalline structures modeling them as fully crystalline or paracrystalline is a restrictive approximation.…”

Section: Introductionmentioning

confidence: 97%

Modeling failure mechanisms of poly(p-phenylene terephthalamide) fiber using reactive potentials

Yılmaz

2015

Computational Materials Science

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“…In highly ordered polyamides the intermolecular attractions are an important aspect of the macroscopic properties [16][17][18][19][20][21][22][23][24][25][26][27] and greatly affect these. Recently, an atomistic modeling method that is applicable to the general study of polymers in a highly ordered, but not necessarily classical crystalline state has been pre~ented~~-~ ').…”

Section: Introductionmentioning

confidence: 99%

Spinning and characterization of fibers from poly(2,6‐dichloro‐p‐phenyleneterephthalamide): a study of constitutional isomerism and solid‐state arrangements by comparison between simulation and experiment

Glomm¹,

Küuchenmeister²,

Neuenschwander³

et al. 1994

Macro Chemistry & Physics

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Fibers of three constitutionally isomeric rigid-rod polymers, produced by polycondensation of 2,6-dichloro-p-phenylenediamine and terephthaloyl dichloride, were spun from nematic solutions and characterized by wide-angle X-ray diffraction (WAXD) measurements and mechanical tests. A post-spin heat treatment was employed to improve the low degrees of orientation and crystallinity that the untreated fibers showed. The dominating crystal structure of constitutionally ordered head-to-head/tail-to-tail fibers seems to be very similar to "Modification 11" of the fibers From poly@-phenyleneterephthalamide) (PPTA), but the fibers do not suffer a comparable structural transformation upon heat treatment. Influences of the constitutional regularity in the chains on the crystal structure, structural order and mechanical properties of the fibers could be observed. Both the observed crystal structure and the experimentally determined mechanical properties agree well with the results of detailed atomistic modeling predictions.

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“…The flexibility of the polymer chains is low due to the absence of free rotations around the Ph-C bond and the Ph-N bond and, so, no regular chain folding or kinks and jogs can be envisaged in the solid polymer. The tensile crystallite modulus has been calculated for the all-trans conformation and the final result is that Kevlar fibers have two separate amorphous and crystalline phases, but they have an extended chain structure or oriented amorphous structure and they may be reasonably considered to be of a more paracrystalline structure 35 .…”

Section: Crystal Structurementioning

confidence: 99%

“…The unit cell has a = 7.87 Å, b = 5.18 Å, c (fiber axis) =12.9 Å -other alternative measured values are tabulated in Table 2. The angle γ = 90° and the crystal structure possesses Pn or P21/n space-group 35,36 . The layer of the hydrogen-bonded chains and the contents of the cell are shown in Figures 9a Figure 9.…”

Section: Crystal 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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Morphology and Structure of Kevlar Fibers: A Review

Cited by 97 publications

References 43 publications

Modeling failure mechanisms of poly(p-phenylene terephthalamide) fiber using reactive potentials

Modeling failure mechanisms of poly(p-phenylene terephthalamide) fiber using reactive potentials

Spinning and characterization of fibers from poly(2,6‐dichloro‐p‐phenyleneterephthalamide): a study of constitutional isomerism and solid‐state arrangements by comparison between simulation and experiment

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

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