Characterization of structural changes in thermally enhanced Kevlar‐29 fiber

Downing, James W.; Newell, James A.

doi:10.1002/app.13021

Cited by 59 publications

(46 citation statements)

References 17 publications

(39 reference statements)

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“…Polyethylene terephthalate (PET) is a typical semi-crystalline polymer consisting of spherulites, or crystalline lamellae linked by amorphous tie-chains [10]. Finally, poly(styreneb-ethylene-butylene-b-styrene) (SEBS), a tri-block copolymer commonly used in shoe soles, asphalt, and adhesives [11], adapts a lamellar structure of alternating polystyrene (PS) and poly(ethylene-butylene) (PEB) domains [12].…”

Section: Continuous Dynamic Analysis Of Kevlar and Nomexmentioning

confidence: 99%

Strain-dependent dynamic mechanical properties of Kevlar to failure: Structural correlations and comparisons to other polymers

Raja

Basu

Limaye

et al. 2015

Materials Today Communications

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The processing of Kevlar to certain strengths by hot-drawing can benefit by quantitative understanding of the correlation between structural and mechanical properties during the pre-drawing process. Here, we use a novel continuous dynamic analysis (CDA) to monitor the evolution in storage modulus and loss factor of Kevlar 49 fibers as a function of strain via a quasi-static tensile test. Unlike traditional dynamic mechanical analysis, CDA allows the tracking of straindependent mechanical properties until failure. The obtained dynamic viscoelastic properties of Kevlar 49 are correlated with structural data obtained from synchrotron radiation analysis and with Raman scattering frequencies. Ratedependent stress-strain results from Kevlar are compared to Nomex, spider silk, polyester and rubber, and provide insight into how the mechanical properties of Kevlar originate from its characteristic structural features. We find that as the storage modulus of Kevlar is essentially equal to the Young's modulus, the measured quantitative relationships between storage modulus and strain can provide insights into the tuning of the mechanical properties of aramid materials for specific applications. On the other hand, the technique of continuous dynamic analysis (CDA) combines the advantages of dynamic mechanical analysis with those of the quasi-static tensile test to quantify the evolution of viscoelastic properties as a continuous function of strain [4]. This is achieved through application of a small harmonic (20 Hz) strain during the tensile deformation. Because the harmonic strain is much smaller in magnitude than the applied quasi-static strain, it remains within the limits of linear viscoelasticity and does not affect the behavior of a quasi-static tensile test. Here, using a specialized electromechanical load cell capable of applying small but continually increasing periodic forces, we employ CDA to monitor the dynamic properties of Kevlar 49 fibers as a function of their strain to failure. We then quantitatively correlate our results to the structural tensile data of Kevlar from previous studies utilizing wide-angle X-ray diffraction (WAXD) [5] and Raman spectroscopy [6], to provide insight into the molecular mechanisms by which Kevlar tolerates stress. The dynamic mechanical behavior of Kevlar is further compared to those of other key structural polymers to quantitatively discern its dynamic responses against known benchmarks. As such, this study presents quantitative information on how the drawing of Kevlar changes its mechanical properties, thereby providing guidelines for the systematic optimization of this important engineering fiber.

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Section: Continuous Dynamic Analysis Of Kevlar and Nomexmentioning

confidence: 99%

Strain-dependent dynamic mechanical properties of Kevlar to failure: Structural correlations and comparisons to other polymers

Raja

Basu

Limaye

et al. 2015

Materials Today Communications

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“…Another type of PPTA fibers, named Twaron  , was produced in 1978 by Teijin Aramid B.V. in Netherland 1,5,[8][9][10][11][12] . Poly (p-phenylene terephthalamide) abbreviated PPTA, are organic fibers acronym originating from aromatic poly (amide) with a distinct chemical composition of wholly aromatic polyamides which at least 85% of amide groups (-CO-NH-) are bond directly to two aromatic rings 2,[12][13][14][15] . Burchill 16 reported that it is largely poly (p-phenylene terephthalamide), Figure 1.…”

Section: Aramid Storymentioning

confidence: 99%

“…They examined the structural mechanism and the mechanical properties of heat treated fibers by means of the thermal and oxidative methods 15,75 .…”

Section: Thermal Ageingmentioning

confidence: 99%

“…The compressive properties of the PPTA fibers have been studied in many literatures 15,90,[107][108][109][110][111][112][113] . Tensile tests of compressively kinked poly(p-phenylene terephthalamide) (PPTA) fibers reveal only a 10% loss in tensile strength after application of compressive strains much greater than the critical strain required for kink band initiation 114 .…”

Section: Compressive Propertiesmentioning

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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“…It reasonably considers to utilize para-aramid fiber which is widely used as protective materials since it has high modulus, strong strength and the flame retardance. There are many inter-chain bonds and these strong intermolecular hydrogen bondings interaction between the carbonyl groups and NH centers make the aramid fiber have a high crystallinity [14,15,16]. Therefore, it is difficulty to dissolve using common solvent.…”

Section: Introductionmentioning

confidence: 99%