Probing the internal structures of Kevlar® fibers and their impacts on mechanical performance

Roenbeck, Michael R.; Sandoz-Rosado, Emil; Cline, Julia; Wu, Vincent; Moy, Paul; Afshari, Mehdi; Reichert, David E.; Lustig, Steven R.; Strawhecker, Kenneth E.

doi:10.1016/j.polymer.2017.09.039

Cited by 44 publications

(58 citation statements)

References 32 publications

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“…It would be of great interest to extend this characterization to Kevlar fibers that (i) constitute new Kevlar classes with unique processing conditions and (ii) are not subjected to microtomy, which can yield significant surface artifacts [ 14 ]. To address these objectives, AM-FM characterization of FIB-notched samples of four Kevlar fiber classes were performed, exploring connections among fiber processing conditions, internal structures, and tensile properties [ 17 ]. Traditional tapping mode topographical maps ( Figure 6(a) ) of FIB-notched surfaces reveal a pleated structure, which is qualitatively consistent across all Kevlar classes explored (K119 (shown), K29, KM2+, and K49) and correlates well with the TEM studies by Dobb et al Significant information is also obtained from transverse-stiffness maps ( Figure 6(c) ) which reveal local material responses to AFM probing throughout the fiber.…”

Section: Resultsmentioning

confidence: 99%

“…The utility of unveiling the internal fiber structure using the FIB-notch sample preparation and AFM-stiffness mapping techniques was recently reported in a work comparing Kevlar fibers with varying processing histories [ 17 ]. In that work, strong direct relationships were made between the fiber microstructures and single-fiber tensile properties.…”

Section: Introductionmentioning

confidence: 99%

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Quantifying High-Performance Material Microstructure Using Nanomechanical Tools with Visual and Frequency Analysis

2018

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High-performance materials like ballistic fibers have remarkable mechanical properties owing to specific patterns of organization ranging from the molecular scale, to the micro scale and macro scale. Understanding these strategies for material organization is critical to improving the mechanical properties of these high-performance materials. In this work, atomic force microscopy (AFM) was used to detect changes in material composition at an extremely high resolution with transverse-stiffness scanning. New methods for direct quantification of material morphology were developed, and applied as an example to these AFM scans, although these methods can be applied to any spatially-resolved scans. These techniques were used to delineate between subtle morphological differences in commercial ultra-high-molecular-weight polyethylene (UHMWPE) fibers that have different processing conditions and mechanical properties as well as quantify morphology in commercial Kevlar®, a high-performance material with an entirely different organization strategy. Both frequency analysis and visual processing methods were used to systematically quantify the microstructure of the fiber samples in this study. These techniques are the first step in establishing structure-property relationships that can be used to inform synthesis and processing techniques to achieve desired morphologies, and thus superior mechanical performance.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Quantifying High-Performance Material Microstructure Using Nanomechanical Tools with Visual and Frequency Analysis

2018

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“…Commercial silicon AFM tips (AC200TS, Asylum Research), having a 10 nm nominal radius and a nominal first bending mode spring constant of 9.7 N/m, were used as received. The spring constant was measured for each lever using a thermal tune that measures the thermal noise across a frequency spectrum in a range around the resonant frequency and applies the equipartition theorem within the Cypher AFM software detailed elsewhere …”

Section: Methodsmentioning

confidence: 99%

Metallo‐supramolecular Crosslinked Polyurethanes

Lambeth

Morgan

Savage

et al. 2019

J Polym Sci B Polym Phys

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The effects of incorporating metal‐binding ligands as chain extenders in polyurethane elastomers were investigated. Segmented polyurethanes based on 2 kDa poly(tetramethylene oxide) (PTMO) and 4,4‐methylenebis(cyclohexyl isocyanate) were polymerized using a two‐step process in which 2,6‐bis(1‐ethyl‐5‐(methoxymethyl)‐1H‐benzo[d]imidazol‐2‐yl)pyridine was added as a chain extender. The resulting polyurethanes were then metallated using stoichiometric amounts of Zn(II) metal salts with different counterions. The resulting metallopolymers have substantially improved Young's moduli, increased failure stress, and improved thermomechanical behavior. The materials were microphase‐separated into anisotropic hard domains within a PTMO matrix. Simultaneous small‐angle X‐ray scattering and tensile testing revealed the minority hard segment domains remain relatively intact during elongation, likely due to the strength of the metal–ligand complex. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 1744–1757

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“…Aramid fibers have an inherent yellowish color that often is a sign of wellknown applications of these fibers. Aramid fibers are good in light-weight applications because the density of the fibers is relatively low, in the order of 1.35-1.5 g/cm 3 . Naturally, the stiffness (modulus) and strength of the fibers finally determine the applications for optimum designs.…”

Section: Applicationsmentioning

confidence: 99%

Advanced Treatments of Aramid Fibers for Composite Laminates

Kanerva¹

2020

Composite and Nanocomposite Materials - From Knowledge to Industrial Applications

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Aramid fibers form an important group of fibers for composite applications. These applications range through lightweight shell structures, protective structures in ballistic applications such as helmets and various shields, protective clothing, and car tires, for instance. For structural applications, the composites of aramid fibers and high performance resins must form integral and strong parts. Therefore, the fiber-matrix interface places a significant role. Numerous surface treatments and fiber modifications have been applied over the years to adjust aramid fibers. On the way to improve and optimize these interfaces, various test methods have been applied. The recent studies apply microtesting, e.g., in the form of microdroplet tests. Furthermore, the material properties of the resin, fiber, and interface are used to create numerical models. However, the current challenge is to collect statistically reliable data as well as the necessary parameters to validate the simulations on different length scales.

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Probing the internal structures of Kevlar® fibers and their impacts on mechanical performance

Cited by 44 publications

References 32 publications

Quantifying High-Performance Material Microstructure Using Nanomechanical Tools with Visual and Frequency Analysis

Quantifying High-Performance Material Microstructure Using Nanomechanical Tools with Visual and Frequency Analysis

Metallo‐supramolecular Crosslinked Polyurethanes

Advanced Treatments of Aramid Fibers for Composite Laminates

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