Structural changes during deformation of Kevlar fibers via on-line synchrotron SAXS/WAXD techniques

Ran, Shaofeng; Fang, Dufei; Zong, Xinhua; Hsiao, Benjamin S.; Chu, Benjamin; Cunniff, Philip M.

doi:10.1016/s0032-3861(00)00460-2

Cited by 156 publications

(140 citation statements)

References 39 publications

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“…In addition, the misorientation (B φ ) did not change at the relatively low temperatures but increased at a high temperature (160 °C) ( Table 4), suggesting that the ordered structure could be disrupted under escalated pretreatment condition (Ran et al, 2001). Notable is that previous SAXS study on fiber suggested that microvoids changed significantly during drying and rewetting (Vickers et al, 2001).…”

Section: Saxs Studymentioning

confidence: 91%

“…In this study, the estimated lengths of the microvoids increased as the temperature increased (Table 4), possibly because of the acid disruption of fiber structure. The length of the equatorial streak, which was considered a reciprocal of the diameter (D) of the microvoids in cellulose fibers (Ran et al, 2001), did not change significantly after acid treatment, indicating that the average diameter did not change.…”

Section: Saxs Studymentioning

confidence: 99%

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Towards understanding structural changes of photoperiod-sensitive sorghum biomass during sulfuric acid pretreatment

Shi

Wang

2013

Bioresource Technology

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Section: Saxs Studymentioning

confidence: 91%

Section: Saxs Studymentioning

confidence: 99%

Towards understanding structural changes of photoperiod-sensitive sorghum biomass during sulfuric acid pretreatment

Shi

Wang

2013

Bioresource Technology

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“…Grujicic et al 56,[62][63][64][65] reported that defect's type, size and concentration are sensitive functions of the PPTA fiber fabrication (polymer synthesis, dope preparation and spinning process) -which are summarized in the present review in section 2.…”

Section: Structural Defectsmentioning

confidence: 95%

“…An outstanding analysis of PPTA fibers at multi scale levels is investigated by Grujicic et al 56,[62][63][64][65] . The computational investigations properly described the material models which are used to achieve the material (PPTA) behaviour at the length-scale levels from chemical structure (atoms) to composite structure (laminate) with brief description in eight levels.…”

Section: Ppta Computational Modellingmentioning

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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“…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.…”

mentioning

confidence: 88%

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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Structural changes during deformation of Kevlar fibers via on-line synchrotron SAXS/WAXD techniques

Cited by 156 publications

References 39 publications

Towards understanding structural changes of photoperiod-sensitive sorghum biomass during sulfuric acid pretreatment

Towards understanding structural changes of photoperiod-sensitive sorghum biomass during sulfuric acid pretreatment

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

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

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