Method for the synthesis of para‐aramid nanofibers

Yeager, Matthew P.; Hoffman, Christopher M.; Xia, Zhiyong; Trexler, Morgana M.

doi:10.1002/app.44082

Cited by 27 publications

(22 citation statements)

References 31 publications

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“…The results are shown in Figure . The broad peaks between 110 and 140 ppm are the aromatic carbons in the backbone, and the smaller peak at 165 ppm results from the carbonyl carbons of the amides …”

Section: Resultsmentioning

confidence: 99%

“…Without sulfuric acid, the ability to synthesize dispersions of PPTA nanofibers was developed via deprotonation in dimethyl sulfoxide (DMSO), but isolation from DMSO and/or extrusion of individual aramid nanofibers (ANFs) was not possible due to limited solubility . To build on that approach, a scalable and practical method was developed to electrospin ANFs via side chain substitutions that enhance polymer solubility in organic solvents . None of these prior efforts to synthesize nanoscale PPTA fibers have reported mechanical properties of single nanofibers; therefore, it is unknown if the fibers are realizing their full theoretical potential, even if synthesis is harsh or challenging.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and mechanical properties of para‐aramid nanofibers

Trexler

Hoffman

Smith

et al. 2019

J Polym Sci B Polym Phys

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Scalable, bottom‐up chemical synthesis and electrospinning of novel Cl‐substituted poly(para‐phenylene terephthalamide) (PPTA) nanofibers are herein reported. To achieve Cl‐PPTA nanofibers, the chemical reaction between the monomers was precisely controlled, and dissolution of the polymer into solvent was tailored to enable anisotropic solution formation and sufficient entanglement molecular weight. Electrospinning processing parameters were studied to understand their effects on fiber formation and mat morphology and then optimized to yield consistently high quality fibers. Importantly, the control of relative humidity during the fiber formation process was found to be critical, likely because water promotes hydrogen bond formation between the PPTA chains. The fiber and mat morphologies resulting from different combinations of chemistry and spinning conditions were observed using scanning electron microscopy, and observations were used as inputs to the optimization process. Tensile properties of single Cl‐PPTA nanofibers were characterized for the first time using a nanomanipulator mounted inside a scanning electron microscope (SEM), and fiber moduli measuring up to 70 GPa, and strengths exceeding 1 GPa were achieved. Given the excellent mechanical properties measured for the nanofibers, this chemical synthesis procedure and electrospinning protocol appear to be a promising route for producing a new class of nanofibers with ultrahigh strength and stiffness. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019, 57, 563–573

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis and mechanical properties of para‐aramid nanofibers

Trexler

Hoffman

Smith

et al. 2019

J Polym Sci B Polym Phys

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“…(a), para‐aramid floc possesses a regular rod‐like shape with a certain rigidity, uniform thickness, smooth and shiny surface indicating a reinforcing agent in many cases . Para‐aramid fibrid shows good flexibility and easier wrapping, indicating good interfacial adhesion . So these two different para‐aramid fibers were introduced into mica‐based paper to investigate the individual effect and combined effect (reinforcing and/or interfacial adhesion effect) on the paper structure and its related physical properties.…”

Section: Resultsmentioning

confidence: 99%

“…41,42 Para-aramid fibrid shows good flexibility and easier wrapping, indicating good interfacial adhesion. 43,44 So these two different para-aramid fibers were introduced into mica-based paper to investigate the individual effect and combined effect (reinforcing and/or interfacial adhesion effect) on the paper structure and its related physical properties.…”

Section: Morphologies Of Para-aramid Flocs and Fibridsmentioning

confidence: 99%

A novel mica‐based composite with hybrid aramid fibers for electrical insulating applications: largely improved mechanical properties and moisture resistance

Zhao

Dang

et al. 2017

Polymer International

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The fabrication of mica‐based composites with good mechanical properties is very important especially for electrical insulation applications. In this study, a new aramid fibrid along with chopped fibers was introduced into a mica system, and the composites were prepared using a papermaking machine. It was found that the mechanical properties of both fibrid–mica composite (F‐M paper) and fiber/fibrid–mica composite (A‐M paper) were largely improved in comparison with the reference sample (M paper) with an increase in the content of fibrid or hybrid floc/fibrid. This enhancement can be attributed to two mechanisms: (1) enhanced interfacial adhesion derived from the addition of fibrids with good flexibility and wrapping properties and (2) significant reinforcing due to the frameworks originating from the addition of chopped flocs with high modulus and rigid‐rod morphology. Interestingly, a synergetic effect of enhanced interfacial adhesion and reinforcing could also be observed when both flocs and fibrids were introduced, which further improved the mechanical properties. Furthermore, the addition of aramid fibrid greatly enhanced the moisture resistance, which expands the potential for mica‐based composites. Thus, we successfully fabricated a mica‐based composite for electrical insulation with good mechanical properties, high end‐use temperature and excellent moisture resistance by adding hybrid aramid fibers. © 2017 Society of Chemical Industry

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“…The diffraction peaks observed at 2 = 24.1°, 27.5°, 28.4° and 42.4° correspond to the (1 1 0), (2 0 0), (0 0 4) and (2 1 1) planes, respectively, which are also present in PPTA fibers. 39 The broad peak centered at around 2 = 20° is attributed to π-π stacking between the 2D layers, where the porphyrin units form an AA type eclipsed stacking. 47 The FT-IR and UV-vis spectra of Porphvlar were compared to those obtained from the molecular porphyrin unit, H2TAPP.…”

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confidence: 99%

Free-base Porphyrin Polymer for Bifunctional Electrochemical Water Splitting

Ge¹,

Lyu²,

Hernandez³

et al. 2021

Preprint

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Projected future global energy demands require sustainable energy sources as alternatives to the current world dependence on hydrocarbon fuels. The production of hydrogen and oxygen gas from water is a promising approach. Currently, water-splitting electrolyzers require precious metals as electrocalysts because they are active and stable. Yet, replacement of these precious metals by cost-effective alternatives is necessary for the economic feasibility of this approach. Here, we describe a molecular based polymeric approach that effectively removes the need to use any metal to electrochemically split water. The incorporation of free-base porphyrin units into a 2D network structure yields a stable and efficient bifunctional electrocatalyst for water oxidation and water reduction that can operate for days at competitive overpotentials comparable to metal based ones.

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Method for the synthesis of para‐aramid nanofibers

Cited by 27 publications

References 31 publications

Synthesis and mechanical properties of para‐aramid nanofibers

Synthesis and mechanical properties of para‐aramid nanofibers

A novel mica‐based composite with hybrid aramid fibers for electrical insulating applications: largely improved mechanical properties and moisture resistance

Free-base Porphyrin Polymer for Bifunctional Electrochemical Water Splitting

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