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1
Bayat, Masoumeh. « Electromagnetic composite nanofibers ». Thesis, University of British Columbia, 2011. http://hdl.handle.net/2429/39894.
Texte intégralRésumé :
Multifunctional composite nanofibers containing magnetite (Fe₃O₄) nanoparticles are developed
in this work. The multifunctional composite nanofibers are proved to be electrically conductive
and magnetically permeable. Polyacrylonitrile (PAN) is used as an appropriate polymer which is
capable of being pyrolized to produce electrically conductive carbon nanofiber matrix. In order
to develop magnetic nanofibers, various amounts of Fe₃O₄ nanoparticles ranging from 3 to
10wt.% are embedded in the PAN nanofiber matrix. In addition, the electromagnetic behaviour
of nanocomposites made of two different sizes (GA:20-30nm and GB:10-20nm) of Fe₃O₄
nanoparticles is examined. Electrospun composite nanofibers are thermally treated at both 700°C
and 900°C to produce electromagnetic carbon nanofiber composites. The composite nanofibers
are characterized using scanning electron microscopy (SEM), transmission electron microscopy
(TEM), X-ray diffractometry (XRD), Raman spectroscopy, four-point probe and
Superconducting Quantum Interference Device (SQUID). Electromagnetic Interference
Shielding Effectiveness (EMI SE) of the pristine carbon nanofibers as well as electromagnetic
composite nanofibers is examined using Vector Network Analyzer with Thru-Reflect-Line
(TRL) calibration. Uniform nanofibers are obtained for all samples with choosing 10wt.% PAN
concentration in Dimethylformamide (DMF) with larger fiber diameters for composite
nanofibers as compared with pristine carbon nanofiber. The magnetic properties of Fe₃O₄
nanoparticles are successfully transferred into the as-spun Fe₃O₄/PAN composite nanofibrous
structure. The electromagnetic properties of the composite materials are tuned by adjusting the
amount and size of Fe₃O₄ nanoparticles in the matrix and carbonization process. By embedding
10wt.% of GA:20-30nm Fe₃O₄ nanoparticle, saturation magnetization (Ms) of 16emu/g is obtained with electrical conductivity of 9.2S/cm for composite nanofiber carbonized at 900°C. However, the Ms and electrical conductivity values respectively decrease to 9.0emu/g and 1.96S/cm for composite made of 10wt.% GB:10-20nm Fe₃O₄ nanoparticle carbonized at 900°C. The high surface area provided by the ultrafine fibrous structures, the flexibility and tuneable electromagnetic properties are expected to enable the expansion of the design options for a wide range of electronic devices such as sensors and actuators as well as Electromagnetic Interference Shielding Effectiveness (EMI SE). The electromagnetic composite nanofibers are demonstrated to act as strong electromagnetic interference shield of up to 70-80dB.
2
Haji, Aminoddin, Komeil Nasouri, Ahmad Mousavi Shoushtari et Ali Kaflou. « Reversible Hydrogen Storage in Electrospun Composite Nanofibers ». Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35201.
Texte intégralRésumé :
Composite nanofibers containing single-walled carbon nanotubes (SWNT) were prepared by using elec-trospinning technique and hydrogen adsorption/desorption isotherms were carried out by a Sieverts appa-ratus at room temperature. The SEM analysis of the nanofibers revealed that the deformation of the nano-fiber increases with increasing SWNT concentration. The diameter of neat nanofibers was below 200 nm and had smooth surface. The surface of the composite nanofibers was rough even by adding low quantity of SWNT. The hydrogen storage results showed an improvement in the adsorption capacity with increasing the SWNT content in composite nanofibers. These nanofibers were evacuated again to remove the ad-sorbed hydrogen at room temperature. Moreover, even though specific surface area and total pore volume were important factors for increasing the capacity of hydrogen adsorption. Finally, maximum adsorption capacity was 0.29 wt % in case of nanofibers with 10 wt % SWNT under 30 bar at 298 K.
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3
Bovicelli, Federico. « On the influence of polymeric nanofibers in laminated composite materials. Studio dell'influenza di nanofibre polimeriche in materiali compositi laminati ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/6784/.
Texte intégralRésumé :
During the last years an increased interest about the reinforcement of laminated composites by means of polymeric nanofibers has been growth. During this master-degree-thesis work, unidirectional and plane-textile composites have been interleaved with Nylon 6.6, PCL and mixed (Nylon 6.6+PCL) nanofibrous mats and the DCB (mode I interlaminar fracture toughness), ENF (mode II interlaminar fracture toughness and DMA (damping capability) tests have been performed. Regarding the interlaminar fracture toughness, marked increases have been recorded; while further investigation about damping capability is requested.
4
Almuhamed, Sliman. « Study and Development of Nonwovens made of Electrospun Composite Nanofibers ». Thesis, Mulhouse, 2015. http://www.theses.fr/2015MULH8864.
Texte intégralRésumé :
L’électrofilage est actuellement la méthode la plus utilisée pour la production de nanofibres grâce à sa simplicité, sa reproductibilité et la possibilité d’être industrialisée. Grâce à leurs propriétés particulières telles qu’un grand rapport surface-volume, une porosité inter-fibre élevée et une grande capacité d’adsorption, les nanofibres électrofilées sont de bons candidats pour de nombreuses applications telles que la filtration, les masques respiratoires, les matériaux composites, etc. Cependant, certaines applications particulières, telles que les capteurs, les systèmes d'administration contrôlée de médicaments ou les super condensateurs, exigent que les nanofibres doivent présenter des propriétés complémentaires telles que la conductivité électrique, la porosité de surface de nanofibres, l’hydrophobicité, ou d’autres propriétés particulières. Certains nanomatériaux comme les nanotubes de carbone, la silice mésoporeuse ordonnée, les argiles, ont des propriétés particulières comme la conductivité électriques élevée des nanotubes de carbone, la porosité des matériaux de silice mésoporeuse ordonnée ou de l’argile. Ces propriétés des nanomatériaux peuvent être les fonctions complémentaires cherchées. Dans notre étude, des non-tissés composés de nanofibres de polyacrylonitrile chargées par nanotubes de carbone à multi-parois (MWNT), de la montmorillonite sodique (MMT-Na) ou de la silice mésoporeuse ordonnée (de type SBA-15), sont produits par électrofilage. Les résultats montrent que l’insertion de MWNT rend le non-tissé conducteur en augmentant la conductivité électrique volumique par six ordres de grandeur (de ~ 2×10-12 à ~ 3×10-6 S/m) avec un très faible seuil de percolation de 0.5 % massique. Lorsque le non-tissé est soumis à une compression, la conductivité électrique volumique augmente en augmentant la pression (jusqu’à ~ 2 kPa). Ces non-tissés conducteurs sont très intéressants pour le développement des capteurs à faible amplitude. Les résultats montrent aussi que l’accessibilité des pores des particules inorganiques (c’est-à-dire, les mésopores de SBA-15 et l’espace interfoliaire de MMT-Na) insérées dans la structure nano fibreuse est encore possible. Il a été trouvé que plus de 50% des mésopores de SBA-15 insérées sont encore accessibles quelles que soit les conditions de l’électrofilage et la fraction massique de SBA-15. En outre, l’insertion de ces particules inorganiques apporte plus de stabilité thermique aux nanofibres compositesElectrospinning is the most common method for the production of nanofibres due to its simplicity, repeatability, and the ability to be scaled up. Owing to their advanced properties like the high surface-to-volume ratio, high interfibrous porosity, high adsorption capacity, etc. electrospun nanofibers are good candidates for many applications such as filtration, respiratory masks, composite materials and others. However, some specific applications including sensors, controlled drug delivery systems, supercapacitors, etc. still require complimentary functions that do not exist in pristine nanofibers in their basic structure like the electrical conductivity, surface porosity of the nanofibers, hydrophobicity, and others.Nanomaterials like carbon nanotubes, ordered mesoporous silica, layered silicate, etc. are characterized by particular properties like the high electrical conductivity of carbon nanotubes, the porosity of ordered mesoporous silica or layered silicate. These particular properties of nanomaterials can fulfill of the targeted functions.In our study, nonwovens made from nanofibers of polyacrylonitrile incorporated with multiwalled carbon nanotubes (MWNT), layered silicate type Na-montmorillonite (Na-MMT) or ordered mesoporous silica type SBA-15 are successfully produced by electrospinning.Results reveal that the incorporation of MWNT altered the electrical state of the nonwoven from insolent to conductor where the volume electrical conductivity increased by six order of magnitude (from ~ 2×10-12 to ~ 3×10-6 S/m) with a very low percolation threshold of about 0.5 wt%. The application of mechanical pressure to the conductive nonwoven causes an increase in the volume electrical conductivity with the increase of the applied pressure (up to ~ 2 kPa). Such conductive nonwoven is very interesting for the development of sensor with low amplitude.Results also show that accessibility of the pores of the inorganic particles (i.e. mesopores of SBA-15 and interlayer space of Na-MMT) incorporated into the nanofibers is still possible. It is found that at least 50% of SBA-15 mesopores are still accessible whatever is the electrospinning conditions and SBA-15 mass fraction. In addition, the incorporation of the studied inorganic particles yields higher thermal stability for the composite nanofibers
5
Antoine, Donley. « Optical Transparent Pmma Composite Reinforced By Coaxial Electrospun Pan Hollow Nanofibers ». Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc271772/.
Texte intégralRésumé :
Electrospinning has been recognized as an efficient technique for the fabrication of polymer fibers. These electrospun fibers have many applications across a broad range of industries. In this research, optical transparent composites were successfully fabricated by embedding polyacrylonitrile (PAN) hollow nanofibers into poly (methyl methacrylate) (PMMA) matrix. The hollow PAN nanofibers were prepared by coaxial electrospinning. The PAN was used as the shell solution, and the mineral oil was used as the core solution. The resulting fibers were then etched with octane to remove the mineral oil from the core. The hollow PAN fibers were then homogeneously distributed in PMMA resins to fabricate the composite. The morphology, transmittance and mechanical properties of the PAN/PMMA composite were then characterized with an ESEM, TEM, tensile testing machine, UV-vis spectrometer and KD2 Pro Decagon device. The results indicated that the hollow nanofibers have relatively uniform size with one-dimensional texture at the walls. The embedded PAN hollow nanofibers significantly enhanced the tensile stress and the Young's modulus of the composite (increased by 58.3% and 50.4%, respectively), while having little influence on the light transmittance of the composite. The KD2 Pro device indicated that the thermal conductivity of the PMMA was marginally greater than the PAN/PMMA composite by 2%. This novel transparent composite could be used for transparent armor protection, window panes in vehicles and buildings, and airplane windshield etc.
6
Vidotti, Hugo Alberto. « O papel da concentração de nanofibras e da composição da matriz resinosa nas propriedades flexurais de compósitos experimentais baseados em nanofibras ». Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/25/25146/tde-26042016-104952/.
Texte intégralRésumé :
O objetivo do presente estudo foi de avaliar a influência de soluções de resina com diferentes proporções de monômeros e diferentes concentrações em massa de nanofibras nas propriedades flexurais de compósitos resinosos experimentais reforçados com nanofibras de poliacrilonitrila (PAN). Materiais e métodos: Nanofibras de PAN foram produzidas pelo processo de eletrofiação e caraterizadas por teste de tração e microscopia eletrônica de varredura (MEV). Os compósitos experimentais foram produzidos pela infiltração das mantas de nanofibras com diferentes misturas de BisGMA-TEGDMA (BisGMA/TEGDMA: proporções em % massa de 30/70, 50/50, e 70/30). Foram incorporadas diferentes concentrações em massa de nanofibras (de 0% a 8%). Espécimes em forma de barra foram seccionados a partir de blocos do compósito experimental e armazenados em água na temperatura de 37oC por 24h anteriormente à realização dos testes de flexão de três pontos. Foram avaliados a resistência flexural (RF), o módulo flexural (MF) e o trabalho de fratura (TF). Resultados: Os testes de tração das nanofibras de PAN demonstraram um comportamento anisotrópico das mantas de nanofibras. As propriedades mecânicas exibiram maiores valores na direção perpendicular ao eixo de rotação do coletor metálico utilizado na produção das fibras por eletrofiação. Maiores proporções de BisGMA nas misturas de resina resultaram em maiores valores de RF e MF, o que não ocorreu para os valores de TF. A adição de diferentes concentrações de nanofibras não afetou as propriedades de RF e MF em comparação com o grupo controle (resina pura) (p>0.05). No entanto, a adição das nanofibras promoveu um aumento significante do TF, principalmente para as misturas de resina com maior proporção de TEGDMA (p<0,05). Significância: A inclusão de nanofibras de PAN em resinas de modo a formar compósitos resinosos reforçados por nanofibras não afetou negativamente as propriedades flexurais do material e resultou em um aumento significativo da tenacidade, uma propriedade desejável para um material a ser utilizado para aplicação restauradora.The present study had the objectives to evaluate the influence of different resin blends concentrations and nanofibers mass ratio on flexural properties of experimental Poliacrylonitrile (PAN) nanofibers reinforced composite. Materials and Methods: Poliacrylonitrile (PAN) nanofibers mats were produced by electrospinning and characterized by tensile testing and scanning electron microscopy (SEM). Experimental resin-fiber composite beams were manufactured by infiltrating PAN nanofiber meshs with varied concentrations of BisGMA-TEGDMA resin blends (BisGMA/TEGDMA: 30/70, 50/50 and 70/30 weight %). The mass ratio of fiber to resin varied from 0% to 8%. Beams were cured and stored in water at 37oC. Flexural strength (FS), flexural modulus (FM) and work of fracture (WF) were evaluated by three-point bending test after 24 hs storage. Results: The tensile properties of the PAN nanofibers indicated an anisotropic behavior being always higher when tested in a direction perpendicular to the rotation of the collector drum. Except for WF, the other flexural properties (FS and FM) were always higher as the ratio of BisGMA to TEGDMA increased in the neat resin beams. The addition of different ratios of PAN fibers did not affect FS and FM of the composite beams as compared to neat resin beams (p>0.05). However, the addition of fibers significantly increased the WF of the composite beams, and this was more evident for the blends with higher TEGDMA ratios (p<0.05). Significance: The inclusion of PAN nanofibers into resin blends did not negatively affect the properties of the composite and resulted in an increase in toughness that is a desirable property for a candidate material for restorative application.
7
Yang, Xiaojiao. « Synthesis and Characterization of Hybrid Metal-Metallic Oxide Composite Nanofibers by Electrospinning and Their Applications ». Thesis, Lyon, 2016. http://www.theses.fr/2016LYSE1022/document.
Texte intégralRésumé :
Nous présentons dans ce manuscrit l'élaboration par électrofilage (ES) de nanofibres hybrides métal/oxyde métallique (HMMOC) et leurs caractérisations physico-chimiques. Leurs utilisations dans le cadre d’applications de type « énergie » et « environnement » ont été évaluées. En particulier, la photocatalyse de nanofibres TiO2-Au pour la dégradation en solution aqueuse du bleu de méthylène et l’utilisation de nanofibres WO3-Au comme capteurs de gaz (VOCs) ont été examinées. En lien étroit avec les résultats obtenus sur l'évaluation des performances comme photocatalyseurs ou capteurs à gaz de ces nouvelles structures HMMOC, l'influence de nombreux paramètres a été étudiée : la concentration en ions aurique, la méthode utilisée pour introduire ces derniers à l’intérieur ou les déposer à la surface des nanofibres d’oxydes et finalement le traitement thermique. En effet, on peut soit mélanger directement, avant la procédure d’électrofilage, la solution contenant les ions aurique à la solution polymérique (composée de PVP, PAN, ou PVA contenant le précurseur d'oxyde métallique), soit déposer sous forme de goutte cette solution d’ions Au à la surface des nanofibres d’oxyde métallique une fois la procédure d’électrofilage effectuée. Quant au traitement thermique, il joue un rôle multiple puisqu’il permet à la fois, d’éliminer les composés organiques des solutions polymériques, participant ainsi à la structuration de la partie oxyde du HMMOC, mais aussi de réduire les ions Au sous forme de nanoparticules.Des résultats prometteurs en photocatalyse ont été obtenus sur des fibres optimisées de TiO2 contenant des nanoparticules d’Au de 10 nm (concentration en Au : 4 wt%). En effet, pour cet échantillon, on montre une dégradation 3 fois plus rapide du bleu de méthylène en solution aqueuse que celle obtenue sur les nanofibres de TiO2 de références et sur le catalyseur commercial P25. De la même manière, des nanofibres de WO3 décorées de nanoparticules d’Au de 10 nm, utilisées comme capteurs de gaz, permettent d’obtenir une réponse 60 fois plus importante que dans le cas de nanofibres de WO3 pure et en améliorant grandement la sélectivité par rapport au n-butanolWe present in this manuscript the elaboration by Electrospinning (ES) process of hybrid metal-metallic oxide composite (HMMOC) nanofibers (NFs), and their physical-chemical characterizations. Their applications, especially the photocatalysis of TiO2-Au composite NFs for photocatalytic degradation for methylene blue (MB) in an aqueous solution and WO3-Au composite NFs for gas sensing of the volatile organic compounds (VOCs) have been investigated. According to the performance evaluation results as photocatalyst or gas sensors, the influence of many parameters have been studied: gold ions concentration, the way to introduce them into or at the NFs surface, typically by mixing them into the polymeric solution (composed of PVP, PAN, or PVA with the metallic oxide precursor) before the ES process or by simple droplet deposition onto the NFs after ES process, and finally the annealing treatment. This latter plays an important role since it both removes the organic components of the polymeric solution, thus forming the metal oxide and in-situ participates to the Au reduction.Concerning the photocatalytic properties, an optimized HMMOC material based on TiO2 NFs including 10 nm Au nanoparticles (NPs) has been obtained and shows 3 times significantly improvement of MB degradation compared to pure TiO2 NFs and the commercial catalyst P25. For gas sensing elaboration, we have shown that a HMMOC material based on WO3 NFs decorated at their surface with 10 nm Au NPs can exhibit 60 times higher response and significantly improved selectivity toward n-butanol compared with pure WO3 NFs
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Roman, Julien. « Mise en forme de matériaux carbonés biosourcés par voie liquide ». Thesis, Bordeaux, 2019. http://www.theses.fr/2019BORD0202/document.
Texte intégralRésumé :
Ce travail de thèse est consacré à la mise en forme de nouveaux matériaux carbonés à partir d’un précurseur biosourcé. Les matériaux carbonés tels que les fibres de carbone utilisés dans les composites sont principalement obtenus à partir de précurseurs d’origine pétrosourcée. Ces précurseurs sont onéreux et incompatibles avec une industrie durable. L’utilisation d’un précurseur biosourcé disponible en grande quantité tel que la lignine permet de pallier ces limitations. La structure moléculaire aromatique et la teneur élevée en carbone de la lignine font d’elle un candidat idéal pour l’élaboration de matériau carboné biosourcé. La lignine a pu être transformée en divers matériaux carbonés tels que des nanofibres de carbone, des tresses de nanofibres de carbone, ou encore des objets 3D composites carbonisés. Ces matériaux ont été obtenus à partir de techniques innovantes que sont l’électrofilage et l’impression 3D. Le tressage des nanofibres de carbone ex-lignine a permis d’évaluer les propriétés mécaniques des fibres de carbone. Les propriétés électrochimiques des tresses de nanofibres de carbone ex-lignine sont apparues intéressantes pour une utilisation potentielle en tant que microélectrodes. La microstructure faiblement organisée du carbone issue de la lignine a pu être améliorée. Un traitement thermique de graphitisation ou un ajout de nanocharges carbonées ont contribué à cette amélioration. Les propriétés mécaniques, structurales et de conductivité électrique des nanofibres nanocomposites ont permis de définir l’influence de l’oxyde de graphène sur la lignine. Un effet composite entre ces deux constituants a pu être observé. L’impression 3D d’encres composites à base de lignine et d’oxyde de graphène a pu être rapportée pour la première fois afin d’élaborer des objets 3D carbonisés denses, organisés et conducteurs d’électricitéThis work is devoted to the preparation of new bio-based carbon materials. Carbon materials, such as carbon fibers used in composites, are mainly obtained from a petroleum precursor. These precursors are expensive and not compatible with a sustainable industry. The use of a bio-based precursor available in large quantities such as lignin makes it possible to overcome limitations of petroleum based precursors. The aromatic molecular structure and high carbon content of lignin make it an ideal candidate for the production of bio-based carbon material. Lignin could be transformed into various materials such as carbon nanofibers, twisted carbon nanofibers, or carbonized composite 3D structures. These materials have been obtained from innovative techniques such as electrospinning and 3D printing. Twisting of the lignin-based-carbon nanofibers allowed for measurements of their mechanical strength. The electrochemical properties of the lignin-based twisted carbon nanofibers are interesting for potential microelectrode applications. The low microstructural order of the carbon from the carbonized lignin has been improved. Graphitization treatment or addition of carbon nanofillers contributed to this improvement. The mechanical, structural and electrical properties of nanocomposite carbon nanofibers illustrate the influence of graphene oxide on lignin. A composite effect between these two components has been observed. The 3D printing of composite inks based on lignin and graphene oxide has been reported for the first time in order to elaborate dense, organized and electrically conductive 3D carbonized structures
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Vincent, Cécile. « Le composite cuivre / nanofibres de carbone ». Phd thesis, Université Sciences et Technologies - Bordeaux I, 2008. http://tel.archives-ouvertes.fr/tel-00377607.
Texte intégralRésumé :
Le matériau composite Cu/NFC (Nano Fibre de Carbone) peut être utilisé en tant que drain thermique par les industriels de l'électronique de puissance. En remplacement du cuivre, il doit combiner une conductivité thermique élevée et un coefficient de dilatation thermique adapté à celui de la céramique du circuit imprimé (alumine ou nitrure d'aluminium). Après avoir étudié les propriétés de la matrice cuivre et des NFC, plusieurs méthodes de synthèse du composite Cu/NFC ont été développées. Le composite a tout d'abord été élaboré par métallurgie des poudres. Puis, dans le but d'améliorer l'homogénéité, il a été envisagé de revêtir individuellement chaque NFC par du cuivre déposé par voie chimique electroless ainsi que par une méthode originale de décomposition d'un sel métallique. Des mesures de densité et de propriétés thermiques (conductivité et dilatation) ainsi que les caractérisations microstructurales de ces matériaux montrent la complexité de l'élaboration d'un tel composite. En effet, la dispersion des nanofibres, la nature des interfaces fibres/matrice et surtout les phénomènes thermiques à l'échelle nanométrique sont autant de paramètres à contrôler afin d'obtenir les propriétés recherchées. La simulation numérique et analytique, qui a été mise en oeuvre en parallèle a été corrélée aux résultats expérimentaux, afin de prédire les propriétés finales de nos matériaux.
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Klose, Carolin, Matthias Breitwieser, Severin Vierrath, Matthias Klingele, Hyeongrae Cho, Andreas Büchler, Jochen Kerres et Simon Thiele. « Electrospun sulfonated poly(ether ketone) nanofibers as proton conductive reinforcement for durable Nafion composite membranes ». Elsevier, 2017. https://publish.fid-move.qucosa.de/id/qucosa%3A72523.
Texte intégralRésumé :
We show that the combination of direct membrane deposition with proton conductive nanofiber reinforcement yields highly durable and high power density fuel cells. Sulfonated poly(ether ketone) (SPEK) was directly electrospun onto gas diffusion electrodes and then filled with Nafion by inkjet-printing resulting in a 12 μm thin membrane. The ionic membrane resistance (30 mΩ*cm2) was well below that of a directly deposited membrane reinforced with chemically inert (PVDF-HFP) nanofibers (47 mΩ*cm2) of comparable thickness. The power density of the fuel cell with SPEK reinforced membrane (2.04 W/cm2) is 30% higher than that of the PVDF-HFP reinforced reference sample (1.57 W/cm2). During humidity cycling and open circuit voltage (OCV) hold, the SPEK reinforced Nafion membrane showed no measurable degradation in terms of H2 crossover current density, thus fulfilling the target of 2 mA/cm2 of the DOE after degradation. The chemical accelerated stress test (100 h OCV hold at 90 °C, 30% RH, H2/air, 50/50 kPa) revealed a degradation rate of about 0.8 mV/h for the fuel cell with SPEK reinforced membrane, compared to 1.0 mV/h for the PVDF-HFP reinforced membrane.
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Haji, A., K. Nasouri, A. M. Shoushtari et A. Kaflou. « Relationship between Single Walled Carbon Nanotubes Individual Dispersion Behavior and Properties of Electrospun Nanofibers ». Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35163.
Texte intégralRésumé :
The dispersion stability behavior of single walled carbon nanotube (SWCNT) has important effects on morphological and mechanical properties of SWCNT/polymer composite nanofibers. The effects of SWCNTs incorporation on the morphological and structural developments and the relation between this develop-ments and mechanical properties of the polyacrylonitrile (PAN) nanofibers were demonstrated. The uni-form, stable dispersion and well oriented SWCNT within the PAN matrix were achieved through using polyvinylpyrrolidone (PVP) as dispersing agent. Our data indicate that with increasing the amount of SWCNT (from 0 to 2 wt %), the average nanofiber diameter was increased from 163±19 nm to 307±34 nm. The analysis of the mechanical properties of the composite nanofibers displays that they exhibit an im-provement in the tensile strength of ∼172% from 3.93±0.45 MPa to 10.74±1.03 MPa, and the elastic modu-lus was increased by ~885% from 61.39±15.58 GPa to 605.08±65.55 GPa, as compared to the pure electro-spun nanofibers. The optimal SWCNT concentration for electrospun nanofibers with better morphological and mechanical properties is ~2 wt %.
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Bai, Jing. « Percolation study of nano-composite conductivity using Monte Carlo simulation ». Orlando, Fla. : University of Central Florida, 2009. http://purl.fcla.edu/fcla/etd/CFE0002644.
Texte intégral
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Shoushtari, A. M., G. Salimbeygi, K. Nasouri et A. Haji. « Fabrication of Homogeneous Multi-Walled Carbon Nanotube/ Poly (Vinyl Alcohol) Composite Nanofibers for Microwave Absorption Application ». Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35587.
Texte intégralRésumé :
Poly (vinyl alcohol) (PVA) / sodium dodecyl sulfate (SDS) / multi walled carbon nanotubes (MWCNT) camposite nanofibers with various MWCNT contents (up to 10 wt%) were fabricated by electrospinning process and their microwave absorption properties were evaluated by a vector network analyzer in the frequency range of 8 – 12 GHz (X-band) at room temperature. The uniform, stable dispersion and well oriented MWCNT within the PVA matrix were achieved through using SDS as dispersing agent. The SEM analysis of the nanofibers samples revealed that the deformation of the nanofibers increases with increasing MWCNT concentration. Very smooth surface of the composite electrospun nanofibers even for the nanofibers with concentration of 10 wt MWCNT have been successfully prepared because of the high stability dispersion of MWCNT. It was observed that absorption microwave properties improved with increasing in the loading levels of MWCNT. Finally, the PVA/SDS/MWCNT composite nanofibers sample with the 10 wt content of MWCNT has shown the reflection loss of 15 dB at the frequency of 8 GHz.
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Greenstein, Katherine E. « Development of chemically active metal oxide composite nanofiber filters for water treatment ». Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/2214.
Texte intégralRésumé :
Small drinking water systems, often financially and resource-limited, face unprecedented challenges due to the current diversity and ubiquity of water pollutants. Well-characterized inorganic legacy pollutants, including arsenic, copper, hexavalent chromium, and lead, remain persistent in drinking water systems. In addition, emerging organic contaminants, like endocrine disrupting compounds and pharmaceuticals, are largely uncharacterized but prevalent in the environment and water supplies, calling into question what levels of these relatively new contaminants are truly safe in drinking water. Point-of-use (POU) and point-of-entry (POE) water treatment devices, installed at a specific tap or at the water entry point to a single facility, respectively, are necessary to ensure safe drinking water in contexts where centralized water treatment is not available or cannot adapt to meet new regulatory standards. While existing POU and POE technologies, including reverse osmosis and packed bed media filters, are effective for removing contaminants, installation costs, energy demands, and spatial footprints of these systems can inhibit their implementation. There is a need for new POU and POE technologies that remove a diversity of water contaminants while maintaining a small application footprint. Nanotechnology, referring to technology using material with at least one dimension or feature less than 100 nm in length, is ideal for meeting this need in drinking water treatment. With high surface area-to-volume ratios, nano-enabled treatment technologies exhibit enhanced reactivity with less material, keeping overall footprint relatively small. Specifically, electrospinning, a process in which a polymer precursor solution is electrified to produce a cohesive sheet of nanofibers, can be used to easily synthesize chemically active nanofiber filters for water treatment applications. In this study, we develop electrospun nanofiber filters that harness nano-scaled hematite (Fe2O3) for sorption of inorganic contaminants (e.g., As, Pb) and nano-scaled titanium dioxide (TiO2) for use with ultraviolet (UV) and visible light as an advanced oxidation process (AOP) for removal of emerging organic contaminants (e.g., benzotriazole, carbamazepine, DEET). Most importantly, we strive to optimize both reactivity and material strength to develop cohesive, durable filtration platforms that overcome barriers to use of nanomaterials in water treatment (e.g., concerns over leaching of nanoparticles deployed as suspensions). Herein, we first demonstrate reactivity optimization of pure (though brittle) TiO2 nanofiber photocatalysts by noble metal catalyst (Au) surface loading. Additionally, we optimize polymer-Fe2O3 composite nanofibers for reactivity while maintaining material flexibility by coating the doped polymer with additional Fe2O3 surfaces available for metal/metalloid uptake. Finally, we apply reactivity optimization and strategies to maintain material strength in the development of carbon/TiO2 nanofiber composites used for (photo)chemical filtration of water containing emerging organic contaminants. Ultimately, we find that nanofiber composites exhibit substantial reactivity and structural integrity in water treatment platforms. Outcomes of this work contribute to making nanomaterials, which have been studied for decades but have yet to be commercially employed for water treatment, practical for chemically active water filtration.
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LIU, XIAOXIAO. « A Preliminary Study on Water Collection Ability of Nanofibers Derived from Electrospun Polymers ». University of Akron / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=akron1573050761831223.
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Khenoussi, Nabyl. « Contribution à l'étude et à la caractérisation de nanofibres obtenues par électro-filage : Application aux domaines médical et composite ». Phd thesis, Université de Haute Alsace - Mulhouse, 2010. http://tel.archives-ouvertes.fr/tel-00685662.
Texte intégralRésumé :
La filature par voie électrostatique consiste à dissoudre un polymère dans un solvant, puis soumettre cette solution à un champ électrostatique intense. Différents paramètres influencent l'obtention, la production et la régularité des nanofilaments obtenus. Parmi ces paramètres, il y a des paramètres physiques inhérents à la cabine de filage, des paramètres électriques et des paramètres liés à la solution. Pour obtenir des nanofilaments, la première étape est de déterminer le ou les meilleurs couples polymère-solvant ainsi que les conditions expérimentales optimales pour obtenir à la fois des produits homogènes et reproductibles. L'obtention de nanofilaments de caractéristiques mécaniques et de structures données est complexe et dépend à la fois de paramètres de filage, mais aussi des propriétés de la solution. Une des propriétés les plus importantes de la solution est sa viscosité. Il a donc été nécessaire d'étudier, pour différents couples solvant-polymère (PA, PAN, PLA, PHEA) leur comportement rhéologique. Ces études rhéologiques ont permises d'expliquer les morphologies des matériaux obtenus par la conformation macromoléculaire de la solution. Les non-tissés de nanofibres obtenus ont été caractérisés par Microscopie à Forces Atomiques (AFM), Microscopie Electronique à Transmission (MET) et à Balayage (MEE) pour les aspects morphologiques. D'autres caractérisations, thermique (DSC), spectroscopique (FTIR) et mécaniques (traction et indentation) ont complété la caractérisation de ces matériaux. A l'issue de l'étude précédente, les nanofibres ont été employées dans deux applications. (1) L'incorporation et la compatibilisation de nanorenforts à l'intérieur d'une matrice polymère (Polyacrylonitrile). L'influence sur les propriétés géométriques des nanofibres de façon globale, et plus finement, la morphologie de surface, ont été observées par une analyse AFM de nano-rugosité. (2) La réalisation à partir d'un biopolymère d'un guide tubulaire permettant la croissance cellulaire et la reconnexion de nerfs sectionnés. Il a fallu pour cela remplir un cahier des charges rigoureux en termes de dimensionnement, de structure, et de propriétés mécaniques.
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Gissentaner, Tremaine D. « Development of Conductive Green Polymer Nano-Composite for use in Construction of Transportation Infrastructure ». Ohio University / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1408697877.
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Ford, Ericka N. J. « Carbon nanotubes as structural templates within poly(vinyl alcohol) composite fibers ». Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45921.
Texte intégralRésumé :
Because the gel-spinning process has the potential to yield fibers of high strength and high modulus, this technique was employed to process continuous filaments of PVA/CNT, having CNTs at ¡Ü1 weight percent of polymer. A gel aging technique was employed with the goal of increasing the draw ratio for composite fibers and for promoting the development of crystalline PVA. Since residual solvent can lower the mechanical properties of drawn fibers, solvent phases of water and dimethyl sulfoxide (DMSO) within the drawn fibers were also characterized. As embedded SWNTs were uniaxially aligned along the drawn fiber axis, they were found to induce preferential alignment in the PVA side groups as well as for the residual solvent. This was attributed to charge transfer between SWNT and the respective functional groups. This orientation behavior has been characterized using Raman spectroscopy and infra-red dichroism. The behaviors of gel crystallization and solvent freezing within PVA/CNT dispersions were studied using thermal analysis and rheology. Carbon nanotubes were found to nucleate PVA crystallization in the gel state. PVA/CNT gel aging behavior was characterized by structural, thermal, and mechanical, and dynamic mechanical means. Gel aging was shown to increase the draw ratio of PVA/CNT fibers, and the development of the higher temperature melting peak was attributed to the draw induced ordering of PVA along CNTs. The scanning electron micrographs of fractured PVA/CNT fibers showed fibrils having an average diameter of about 22 nm. The storage modulus of aged gel was a function of solvent diffusion, which changed with aging time. CNTs were shown to have stabilized the gel network, as characterized by the dynamic mechanical properties, and to provide nucleation sites for the ordering of PVA chains, as characterized by WAXD.
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Subir, Kumar Biswas. « Optically Transparent Nanocellulose-Reinforced Composites via Pickering Emulsification ». Kyoto University, 2019. http://hdl.handle.net/2433/244562.
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Zogata, Stanislav. « Anorganická nanovlákna v žárobetonech ». Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2017. http://www.nusl.cz/ntk/nusl-265650.
Texte intégralRésumé :
This work deals with the use of inorganic nanofibers in refractory castables. The thesis describes some of the results of previously conducted research on nanofibers. Also description of nanofibres, production and distribution. The experimental part is focused on studying the interaction of Al2O3 and SiO2 nanofibres with aluminate cement. The main subject of investigation is a dispersion of nanofibers using a surfactant and ultrasonication.
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Valarezo, Valdez Benito Eduardo. « Innovative processes for the production of new nanocomposite materials by electrospinning technique ». Doctoral thesis, Universita degli studi di Salerno, 2013. http://hdl.handle.net/10556/1474.
Texte intégralRésumé :
2011 - 2012The technical parameters for electrospinning solutions of biodegradable polymers poly(ε-caprolactone), poly(lactic acid) and their composites with active molecules were defined and set up. A trial-and-error approach has been employed by varying solution properties and processing parameters to obtain uniform defect-free fibers. Amoxicillin drug was intercalated in layered double hydroxide nanoparticles by coprecipitation and then the modified nanohybrid was successfully encapsulated at different concentrations into poly(ε-caprolactone) matrix by the electrospinning technique. Non-woven fibrous mats were fabricated and characterized in terms of morphology, in vitro release and antibacterial properties. Blends of poly(lactic acid) and poly(ε-caprolactone), loaded with different amounts of amoxicillin were electrospun to investigate the release behaviour and obtain a controlled and tuneable release. Morphology and thermal behaviour were found dependent on the component ratio as well as on the incorporated drug amount. [edited by author]
XI n.s.
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Dong, S., D. Wang, Ashraf F. Ashour, B. Han et J. Ou. « Nickel plated carbon nanotubes reinforcing concrete composites : from nano/micro structures to macro mechanical properties ». Elsevier, 2020. http://hdl.handle.net/10454/18205.
Texte intégralRésumé :
YesOwing to their small size, good wettability, uniform dispersion ability and high thermal properties, the nickel-plated carbon nanotubes (Ni-CNTs) with different aspect ratios are used to reinforce reactive powder concrete (RPC) through modifying the nano/micro- structural units of concrete. Incorporating only 0.075 vol% of Ni-CNTs (0.03 vol% of CNTs) can significantly increase mechanical properties of RPC. The enhancement effect on compressive strength caused by the incorporation of Ni-CNTs with aspect ratio of 1000 reaches 26.8%/23.0 MPa, mainly benefiting from the high polymerization C-S-H gels, low porosity, and refined pore structure. The 33.5%/1.92 MPa increases of flexural strength can be attributed to the decrease of large pore, original cracks, molar ratio of CaO to SiO2, and gel water content when Ni-CNTs with aspect ratio of 125 are added. Ni-CNTs with aspect ratio of 1500 have the largest utilization rate of being pulled-out, resulting from the improvement of dispersibility and the pining effect of nickel coating and then leading to the increased toughness. Therefore, incorporating Ni-CNTs can fundamentally modify the nano/micro- scale structural nature of RPC, providing a bottom-up approach for controlling the properties of RPC.
Funding supported from the National Science Foundation of China (51908103 and 51978127) and the China Postdoctoral Science Foundation (2019M651116).
The full-text of this article will be released for public view at the end of the publisher embargo on 7th Dec 2021.
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Oubenali, Mustapha. « Synthèse par dépôt chimique en phase vapeur catalytique (C-CVD) de nanostructures de carbone et leurs applications en catalyse et pour des matériaux composites ». Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0058/document.
Texte intégralRésumé :
Dans ce travail, nous décrivons les différentes formes, la structure, les propriétés et la croissance catalytique de nanotubes et nanofibres de carbone (Chapitre I). L'hydroxyapatite a été utilisée comme support de la phase active pour la synthèse de nanotubes de carbone multi-feuillet (MWCNTs) et de nanofibres de carbone (CNFs-H) par la technique de dépôt chimique en phase de vapeur catalytique (C-CVD) en lit fluidisé (Chapitre II). Après l'élimination du support par un simple lavage à l'acide chloridrique dilué, une étude théorique et expérimentale de l'oxydation de la surface de nanotubes de carbone par un traitement à l'acide nitrique a permis d'une part d'identifier et de quantifier les groupes formés à la surface de nanostructures carbonées et d'autre part de proposer un mécanisme pour la formation de ces groupes (Chapitre III). Les matériaux résultants après génération des fonctions carboxyliques de surface ont été utilisés comme support de catalyseur. L'hydrogénation du p-halogénonitrobenzène a été choisit comme réaction modèle pour comparer les performances catalytiques de catalyseurs à base de ruthénium en fonction de la nature du support utilisé, MWCNTs ou CNFs-H. L'influence de certains paramètres tels que la température, la nature du substrat et un traitement thermique du catalyseur (activation) est présentée. Une explication des performances catalytiques est proposée après caractérisation du catalyseur par MET, TPD, TPR et PZC (Chapitre IV). Les nanostructures carbonnées produites et caractérisées ont été utilisées comme charge de renforcement d'hydroxyapatites connue comme biomatériaux. Nous avons étudié en particulier la capacité de germination du phosphate octocalcique par la méthode de croissance cristalline à composition constante (C4) (Chapitre V)In this work, we describe the different forms, the catalytic growth, the structure and properties of carbon nanotubes and nanofibres (Chapter I). Hydroxyapatite was used as catalyst support for the synthesis of multi-walled carbon nanotubes (MWCNTs) and nanofibres (CNFs) by catalytic chemical vapour deposition (C-CVD) in a fluidized bed reactor (Chapter II). After support removal by washing with diluted hydrochloric acid, a theoretical and experimental study of surface oxidation of carbon nanotubes by nitric acid treatment has been performed. It allows to identify and quantify the groups formed on the surface of carbon nanostructures and also to propose a mechanism for the formation of these groups (Chapter III). The functionalized nanotubes and nanofibers have been used as supports for heterogeneous catalysis. The hydrogenation of p-halonitrobenzene was used as model reaction to compare the catalytic performances of ruthenium supported on MWCNTs or CNFs-H catalysts. The influence of experimental parameters such as temperature, nature of the substrate and prior heat treatment (activation) of the catalyst on the catalytic activity and selectivity is presented. The catalytic performances have been correlated to the structure of the catalyst as determined from TEM, TPD, TPR and PZC analysis (Chapter IV). The carbon nanostructures produced have also been used as reinforcement fillers for hydroxyapatite-nanotube composites. We have studied in particular, the germination of octacalcium phosphate crystals under conditions of constant solution composition on the surface of the composite (Chapter V)
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Hsieh, Feng-Hsu. « Nanofiber reinforced epoxy composite ». Ohio : Ohio University, 2006. http://www.ohiolink.edu/etd/view.cgi?ohiou1146149557.
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Abchiche, Bruno. « Augmentation de la limite élastique des composites à matrice céramique : SiC/SiC ou SiC/MAC ». Thesis, Bordeaux 1, 2013. http://www.theses.fr/2013BOR14903/document.
Texte intégralRésumé :
Les matériaux composites connaissent un large succès. En effet les Composites à Matrice Céramique (CMC) fonctionnant à haute température ont des performances inégalées en termes de fatigue thermomécanique. La durée de vie des CMC est pourtant limitée en raison de l'apparition précoce de fissures matricielles, ouvrant autant de portes à des environnements agressifs, entraînant un abattement prématuré des propriétés mécaniques. Arriver à retarder la fissuration matricielle devient donc une étape clé pour une future importante utilisation des CMC dans l'aéronautique ou l'aérospatial. Les travaux de cette thèse se sont inscrits dans cette logique, où pour protéger les fibres et l'interphase de l'oxydation et de la corrosion, les propriétés de la matrice céramique ont tenté d'être modifiées par l'incorporation de nanofibres en leur sein et par l'émoussement de leurs macropores résiduelsAbstract
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Urbanetto, Peres Bernardo. « Experimental dental composites with electrospun nanofibers and nanofibrous composites ». Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/58069.
Texte intégralRésumé :
Electrospun nanofibers with and without nanoparticles are poorly explored in dental research. Nanocrystalline cellulose is a nanoparticle with distinguished properties that has already been associated with nanofibers, but yet not applied to any dental aspect.
The objective of this work was to investigate the use of polyacrylonitrile (PAN) nanofibers containing nanocrystalline cellulose (NCC) in the light of the mechanical behavior of fibrous mat and experimental dental composites. Three experiments were performed to answer the following research questions: 1) Can nanocrystalline cellulose improve mechanical properties of polyacrylonitrile nanofiber meshes? 2) Does the method of dispersion (simple mixture vs. with solvent exchange) of NCC in PAN solution affect fiber formation and the respective properties of the meshes? and 3) Can NCC-containing PAN electrospun nanofibers affect flexural properties of experimental dental composites?
Results showed that nanocrystalline cellulose, at low concentrations, significantly increases PAN nanofibers tensile properties (chapter 2). Dispersion methods affected both the morphology and mechanical properties of the fibers (chapter 3). Finally, when NCC-containing PAN nanofibers were used to produce experimental dental composites, there was a significant improvement in flexural strength and work of fracture (chapter 4).
In conclusion, the findings indicated that the use of electrospun nanofibers and nanofibres containing nanoparticles is a promising approach to reinforce dental composites.Dentistry, Faculty of
Graduate
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Green, Keith Jamahl. « Multiscale fiber reinforced composites using a carbon nanofiber/epoxy nanophased matrix processing, properties, and thermochemical behavior / ». Birmingham, Ala. : University of Alabama at Birmingham, 2007. https://www.mhsl.uab.edu/dt/2007m/green.pdf.
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Vincent, Cécile Silvain Jean-François Heintz Jean-Marc. « Le composite cuivre / nanofibres de carbone ». [S. l.] : Bordeaux 1, 2008. http://tel.archives-ouvertes.fr/tel-00377607.
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Mannino, Salvatore. « Electrospun nanofibres for multifunctional composites ». Doctoral thesis, Università di Catania, 2016. http://hdl.handle.net/10761/3953.
Texte intégralRésumé :
Electrospun veils from copolyethersulfones (coPES) were prepared as soluble interlaminar membranes for carbon fiber/epoxy composites. Dissolution trials were carried out to understand the curing cycle. Dry carbon fabrics were covered with electrospun veils and then infused with an unmodified epoxy resin to prepare reinforced laminates. Unreinforced samples with no carbon fabrics were also studied. The coPES9k veils showed full solubility and homogenous morphology. Unreinforced samples, modified by coPES9k veils, showed only minor morphological differences compared to epoxy/coPES blends obtained from coPES9k powder predissolution. The coPES20k veils showed undissolved fibers and inhomogeneous morphologies when blended with an epoxy in the unreinforced samples. Industrial upscaling of the electospinning process was achieved with commercial polyethersulfones provided by Solvay. The veil-toughening concept was demonstrated by increases in the fracture toughness values obtained with respect to unmodified resins. Also nanofilled-fibers were produced and applied as interlaminar toughening veils. The use of nanofibers as carriers for nanofillers was demonstrated by SEM, EDX and TEM analysis.
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Murphy, Maria A. « Electrochemistry of carbon nanofibre composite films ». Thesis, Loughborough University, 2006. https://dspace.lboro.ac.uk/2134/33627.
Texte intégralRésumé :
The work carried out for this thesis focussed on four main areas: (i) the examination and optimisation of the conditions for carbon nanofibre (CNF) growth, both unsupported and as films on substrates; (ii) the electrochemical characterisation of the CNF material before (as-grown) and after solubilisation (oxidation); (iii) the formation and investigation of CNF thin film electrodes; and (iv) the (co-)deposition of the CNFs with metals from aqueous plating solutions. CNFs are grown at an iron nanoparticle catalyst produced from an iron oxide precursor. After exploratory work with different types of iron oxide precursors, a suitable and universally applicable catalyst is identified. CNFs are characterised by electron microscopy, spectroscopy, and electrochemistry. When grown onto a ceramic substrate, the 'as-grown' CNF material is shown to act as a porous, high surface area electrode with the ability to strongly adsorb aromatic molecules, such as hydroquinone, benzoquinone, and phenol.
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Yang, Xianpeng. « Strong Cellulose Nanofiber Composite Hydrogels via Interface Tailoring ». Kyoto University, 2020. http://hdl.handle.net/2433/253333.
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Qua, E. H. « High performance composites made from cellulose nanofibres ». Thesis, Queen's University Belfast, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.517508.
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Higgins, Bernadette Ann. « Carbon Nanofiber-Polymer Composites for Electronic Applications ». University of Akron / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=akron1143655787.
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Andrade, Mahecha Margarita Maria 1979. « Microcompósitos, nanocompósitos e coberturas a base de materiais biodegradáveis obtidos a partir do Biri (Canna indica L.) ». [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/256463.
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Orientadores: Florencia Cecilia Menegalli, Delia Rita Tapia BlácidoTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
Made available in DSpace on 2018-08-20T05:16:21Z (GMT). No. of bitstreams: 1 AndradeMahecha_MargaritaMaria_D.pdf: 4721286 bytes, checksum: d81a0051c1f91a999e9ea8c3e9fe0b20 (MD5) Previous issue date: 2012
Doutorado
Engenharia de Alimentos
Doutor em Engenharia de Alimentos
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Lin, Li-Ting. « Structure and properties of lignin-based composite carbon nanofibres ». Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/63417.
Texte intégralRésumé :
This research investigates the feasibility of developing value-added products from lignin in nanofibre form for structural and functional applications. Specifically, softwood Kraft lignin (SKL) was used as the precursor to fabricate nanofibres via the electrospinning process and then converted into carbon nanofibres (CNF). The mechanical properties of SKL nanofibres were characterized for structural applications at the nanofibre mat level and the single nanofibre level. The electrochemical performance of SKL CNFs was characterized for functional applications at the nanofibre mat level.
This research harnessed different processing methods through hierarchical improvements of the mechanical properties of SKL CNF. The mechanical properties of SKL nanofibre mats were improved by the reduction of nanofibre diameter through the optimization of electrospinning process. The mechanical properties of SKL nanofibres gained an order of magnitude improvement through heat treatment processes of thermo-stabilization and carbonization. Aligned nanofibre mats were successfully fabricated via the rotating drum method resulting in further enhancement of the mechanical properties of SKL CNF. Single-walled carbon nanotube (SWNT)-SKL core-shell composite nanofibres were successfully fabricated via the emulsion electrospinning process. The mechanical properties of the SWNT/SKL composite nanofibres were found to increase as the percent of SWNT increases.
This research also investigated the mechanical properties translation between SKL single nanofibres and their fibre assemblies. The mechanical properties of the SKL single nanofibres were characterized and then analyzed by the statistical Weibull distribution. The experimental results were in good agreement with the analytical values.
A prototype supercapacitor (SC) cell using SKL-based CNF as binder-free electrodes was constructed to demonstrate the feasibility of the SKL CNF for functional applications. The electrochemical performance of the SC cell was characterized and the energy density and power density of the SC cell were found to meet the requirement for commercial products.
In summary, this research sheds light on our understanding of the mechanism of the mechanical properties improvement of SKL CNF, which helps guide the tailoring of the mechanical performance of SKL CNF. Moreover, the electrochemical performance of SKL-based CNFs demonstrated that they are promising candidates as electrode materials for SC and a wide range of energy storage devices.Applied Science, Faculty of
Materials Engineering, Department of
Graduate
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Choi, Jonghyun. « Nanofiber Network Composite Membranes for Proton Exchange Membrane Fuel Cells ». Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1260461818.
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Mushi, Ngesa Ezekiel. « Chitin nanofibers, networks and composites : Preparation, structure and mechanical properties ». Doctoral thesis, KTH, Biokompositer, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-155528.
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Chitin is an important reinforcing component in load-bearing structures in many organisms such as insects and crustaceans (i.e. shrimps, lobsters, crabs etc.). It is of increasing interest for use in packaging materials as well as in biomedical applications. Furthermore, biological materials may inspire the development of new man-made material concepts. Chitinmolecules are crystallized in extended chain conformations to form nanoscale fibrils of about 3 nm in diameter. In the present study, novel materialshave been developed based on a new type of chitin nanofibers prepared from the lobster exoskeleton. Improved understanding about effects of chitin from crustaceans and chitin material preparation on structure is provided through Atomic Force Microscopy(AFM) (paper I&II), Scanning Transmission Electron Microscopy(STEM) (paper I&II), X-Ray Diffraction (XRD), Intrinsic Viscosity, solid state 13C Nuclear Magnetic Resonance (NMR) (paper II), Field Emission Scanning Electron Microscopy(FE-SEM) (paper I, II, III, IV & V), Ultraviolet-Visible Spectrophotometryand Dynamic Light Scattering (DLS) (paper III). The presence of protein was confirmed through colorimetric method(paper I & II). An interesting result from the thesis is the new features of chitin nanofiber including small diameter, high molar mass or nanofiber length,and high purity. The structure and composition of the nanofibers confirms this (paper I & II). Furthermore, the structure and properties of the corresponding materials confirm the uniqueness of the present nanofibers: chitin membrane (I & II), polymer matrix composites (III),and hydrogels (paper IV). Improved mechanical properties compared with typical data from the literature were confirmed for chitin nanofiber membranes in paper II, chitin-chitosan polymer matrix composites in paper III, and chitin hydrogel in paper IV. Mechanical tests included dynamic mechanical analysis and uniaxial tensile tests. Mechanical properties of chitin hydrogels were evaluated based onrheological and compression properties (paper IV). The values were the highest reported for this kind of chitin material. Furthermore, the relationships between materials structure and properties were analyzed. For membranes and polymer matrix nanocomposites, the degree of dispersion is an important parameter. For the hydrogels, the preparation procedure is very simple and has interesting practical potential. Chitin-binding characteristics of cuticular proteins areinteresting fornovel bio-inspired material development. In the present work(paper V), chitin nanofibers with newfeaturesincluding high surface area and low protein content were combined with resilin-like protein possessing the chitin-binding characteristics. Hydrated chitin-resilin nanocomposites with similar composition as in rubber-like insect cuticles were prepared. The main objective was to improve understanding on the role of chitin-binding domain on mechanical properties. Resilin is a rubber-like protein present in insects. The exon I (comprising 18 N-terminal elastic repeat units) together with or without the exon II (a typical cuticular chitin-binding domain) from the resilin gene CG15920 found in Drosophila melanogasterwere cloned and the encoded proteins were expressed as soluble products in Escherichia coli.Resilin-like protein with chitin-binding domain (designated as ResChBD) adsorbedin significant amount to chitin nanofiber surface andprotein-bound cuticle-like soft nanocomposites were formed. Although chitin bindingwas taking place only in proteinswith chitin-binding domain, the global mechanical behavior of the hydrated chitin-resilin nanocomposites was not so sensitive to this chitin-resilin interaction. In summary, chitin is an interesting material component with high potential as mechanical reinforcement in a variety of nanomaterials. The present study reports the genesisof novel chitin nanofibers and outlines the basic relationships between structure and properties for materials based on chitin. Future work should be directed towards both bio-inspired studies of the nanocomposite chitin structures in organisms, as well as the industrial applications of chitin waste from the food industry. Chitin nanofibers can strengthen the properties of materials, andprovide optical transparency as well as biological activities such as antimicrobial properties.QC 20141110
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Morosko, Jason M. « Composite Discharge Electrode for Electrostatic Precipitator ». Ohio University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1173374043.
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Wu, Jie. « Extraction of chitin nanofibers and utilization for sustainable composites and foams ». Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/54006.
Texte intégralRésumé :
Developing renewable materials to reduce the dependence on fossil fuel as a feedstock for a wide range of applications is becoming increasingly acknowledged as important in society. Chitin, the second most abundant biopolymer in nature, is an ideal candidate for diverse applications because of its remarkable properties, such as abundance, renewability, biodegradability, biocompatibility, antibacterial activity, chemical functionality, and high stiffness and strength. Despite these inherent advantages, chitin is currently still underutilized mainly due to its strong molecular interactions, which make it insoluble in common solvents. Currently, its major applications are limited to biomedical engineering, such as tissue engineering, wound dressing and sutures.
This thesis aims to explore and enable the potential utilization of chitin in other fields where it may serve as a renewable functional advanced material. Here, a number of novel chitin-based materials were developed successfully without employing chitin dissolution. These include chitin nanofibers (CNFs), porous chitin with tunable structures, chitin-reinforced polymer composites and chitin-stabilized aqueous foams. Moreover, the properties of these materials including interfacial, optical, thermal, and mechanical characteristics were determined, and their potential utilizations were demonstrated.
Briefly, in chapter 2, CNFs with diameters of ~20 nm were successfully extracted from crab α-chitin by a high pressure homogenization process. The produced CNFs were dispersed well in water without forming strong network structures due to their electrostatic repulsions. The obtained CNF film has a high residue amount (40%) when heated up to 1000 ˚C. Meanwhile, it exhibited high optical transparency as well as great gas barrier properties. In chapter 3, on the basis of the obtained CNFs in chapter 2, versatile porous structures including oriented sheets and three-dimensional aperiodic nanofiber networks were achieved by using a freeze drying technique. Since the formation of nanofibrous structures cannot be predicted by the widely-used particle encapsulation model, a modified structure formation mechanism was proposed. In chapter 4, the structure-property relationships of the CNF/poly(ethylene oxide)(PEO) nanocomposites were established. We demonstrated that the CNFs formed network structures in PEO matrix and had hydrogen bonding interaction with PEO. The CNFs can greatly enhance the mechanical properties of PEO, such as elastic modulus and tensile strength. In chapter 5, the aqueous foams stabilized by high-aspect-ratio CNFs were developed. The created foams exhibited strong hindrance on film drainage, coalescence and disproportionation. The fibrillated CNFs alone were not able to stabilize air bubbles, but the addition of small amounts of valeric acids in CNF dispersion can make chitin foamable. The results clearly showed that valeric acid modified CNFs reduced the surface tension of aqueous dispersion and were attached at the air-water interface.
Overall, this research has provided many new insights for the fabrication, characterization, and utilization of chitin, and has built a solid foundation for further exploiting chitin for diverse applications.
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Samalot, Rivera Francis J. « Processing, characterization and modeling of carbon nanofiber modified carbon/carbon composites ». Birmingham, Ala. : University of Alabama at Birmingham, 2007. https://www.mhsl.uab.edu/dt/2008r/rivera.pdf.
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Thesis (Ph. D.)--University of Alabama at Birmingham, 2007.Additional advisors: Krishan K. Chawla, Derrick Dean, Yogesh Vohra, Mark Weaver. Description based on contents viewed Feb. 13, 2009; title from PDF t.p. Includes bibliographical references (p. 174-186).
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Frankievicz, Raysa. « PROPRIEDADES REOLÓGICAS, TÉRMICAS E MECÂNICAS DE MISTURAS DE CELULOSE BACTERIANA E POLIPROPILENO ». UNIVERSIDADE ESTADUAL DE PONTA GROSSA, 2014. http://tede2.uepg.br/jspui/handle/prefix/1463.
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Previous issue date: 2014-08-13Due to environments problems caused by synthetic plastic, there is currently a search for replacing these materials with biodegradable materials. The study related to composites and nanocomposites formed from biodegradable materials and synthetic matrices has increased last years, and it has shown that these materials are very promising respect to biodegradation processes, besides presenting better properties than their pure components. In this work, it has been emphasized the production of nanofibers bacterial cellulose composite in a polypropylene matrix. The production of nanofibers from bacterial cellulose (BC) has been made in colloid mill. The material has been processed in a twin screw extruder in proportions of 1 %, 3% and 5% (w/w) of bacterial cellulose and coupling agent has been used as graphitized PP with maleic anhydride. The samples have been characterized by thermogravimetric analysis (TGA), x-ray diffraction (XRD), rheological characterization, infrared spectroscopy (FTIR), colorimetry, scanning electron microscopy (SEM), and tensile strength and impact. The TGA results have shown a single stage of mass loss for all samples, and thermal stability increase with filler concentration increase, which can be associated with the fiber-matrix interactions. In the XRD results, the PP has showed only the α phase remaining in the samples containing CB. In the rheological analysis, the complex viscosity has been maintained for samples containing 1% and 3% CB and pure PP, decreasing only for the 5% CB. In additional, It has been observed an enlargement of the molar mass distribution through a tendency reduction in the intersection point of G' and G". In the tensile strength, the elastic modulus has not undergone significant changes, the yield stress has decreased according to the load increasing, however it there have been significant changes with the load concentration increment. The impact strength has decreased for all samples with CB compared to pure PP. The microscopy has showed a good adhesion between fiber and matrix with bacterial cellulose clusters formation. By colorimetry process, it has been found caramelization of bacterial cellulose during the process of extrusion and injection, which causes browning of the samples.
Devido aos problemas ambientes causados pelos plásticos sintéticos, existe atualmente uma busca pela substituição desses materiais por materiais biodegradáveis. O estudo em relação a compósitos e nanocompósitos formados por materiais biodegradáveis e matrizes sintéticas vem crescendo nos últimos anos. Tem-se demostrado que esses materiais são muito promissores em relação aos processos de biodegradação, além de apresentarem propriedades melhores do que seus componentes puros. Neste trabalho foi visada a produção de um compósito com celulose bacteriana nanofibrilada em uma matriz de polipropileno. A produção das nanofibras de celulose bacteriana (CB) foi realizada em moinho coloidal. O material foi processado em extrusora dupla rosca nas proporções de 1%, 3% e 5% (p/p) de celulose bacteriana e como agente compatibilizante foi utilizado PP grafitizado com anidrido maleico. As amostras foram caracterizadas por análise termogravimétrica (TGA), difratometria de raio-x (DRX), espectroscopia de infravermelho (FTIR), análise reológica, resistência a tração e impacto, microscopia eletrônica de varredura (MEV) e colorimetria. Os resultados de TGA demostraram um único estágio de perda de massa para todas as amostras, e um aumento da estabilidade térmica conforme aumenta a concentração de carga, que pode estar associado com as interações fibra-matriz. Nos resultados de raio-x o PP apresentou apenas a fase α, mantendo-se para as amostras contendo CB. Nas análises reológicas, a viscosidade complexa manteve-se para as amostras de 1% e 3% de CB e para o PP puro, diminuindo apenas para a amostra com 5% de CB. Também observou-se um alargamento da distribuição da massa molar através de uma tendência na redução do ponto de cruzamento de G’ e G”. Na resistência à tração, o módulo elástico não sofreu alterações significativas, a tensão de escoamento reduziu com a inserção de carga, porém, não houve variação significativas com o aumento da concentração da carga. A resistência ao impacto reduziu para todas as amostras contendo celulose bacteriana em relação ao PP puro. A microscopia revelou uma boa adesão entre a fibra e a matriz com a formação de aglomerados de celulose bacteriana. Através da colorimetria verificou-se o processo de caramelização da celulose bacteriana durante o processo de extrusão e injeção, o que provoca o escurecimento das amostras.
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Aşcioğlu, Birgül Adanur Sabit. « Manufacturing and heat transfer analysis of nano-micro fiber composites ». Auburn, Ala., 2005. http://repo.lib.auburn.edu/2005%20Summer/doctoral/ASCIOGLU_BIRGUL_5.pdf.
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Bertolucci, Federico. « Controlling strain stiffening in elastomeric composites by nanofiber network architecture ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
Trouver le texte intégralRésumé :
In order to reduce the invasiveness of implantable electronic sensor devices, a technology is needed that could create devices that behave soft and flexible as biological tissue but at the same time maintain their electronic functionality and resist to a high values of sheer and tensile stress. The main problem consists in producing a biocompatible material that stiffens at excessive strain and thus could prevent crack formation and delamination in the more fragile thin functional electronic layers. This thesis presents the methodology to fabricate and characterize a smart composite material composed by polymer nanofiber networks incorporated in an elastomeric matrix. Nanofiber networks of the biocompatible polymer Poly(L-lactic acid) (PLLA) are produced by electrospinning. The polymer Polydimethylsiloxane (PDMS) is used as the elastomeric matrix. The objective is to achieve a significant strain-stiffening transition by introducing a nanofiber network with controlled architecture. To this end a methodology is introduced that enables to synthetize polymer nanofibers with controlled curvature. Dynamical mechanical analysis (DMA) and Atomic Force Microscopy (AFM) are employed to characterize the mechanical properties of the composite material as well as of its single components. The results indicate that the mechanical response of the polymer can be largely controlled by the nanonetwork architecture. Stiff response to tensile stress is obtained when the fibers are straight and aligned in the stress direction. Soft and stretchable response results when fibers are curved or oriented parallel to the strain direction. The introduction of the methodology for fabrication as well as the characterization of such nanonetwork composites with controlled architecture will pave the way for further systematic studies leading to composites with tunable strain stiffening transition.
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Hu, Zhe-chen, et 胡哲誠. « Electrospun Alginate/Polycaprolactone Composite Nanofibers for in-situ Transfection ». Thesis, 2013. http://ndltd.ncl.edu.tw/handle/59658825754872786351.
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碩士國立中央大學
化學工程與材料工程學系
101
To regulate in situ gene delivery from biomaterial scaffolds, electrospun alginate nanofibers were applied to adsorb DNA/polyethylene (PEI) complex. The transfection efficiency increased with increasing deposited nanofibers. However, alginate was not favor for cell adhesion. Therefore, biocompatible poly (ε-poly olactone) (PCL) nanofibers was coelectrospun with alginate to increase biocompatibility. The scanning electron microscopy and fluorescent dye staining results suggested that the definite fiber ratios could be controlled. In addition, contact angle and FT-IR results also indicated that the properties of composite fibers can be regulated by the fiber ratios. The in situ transfection results demonstrated that the incorporated PCL fibers improved biocompatibility; however, the transfection efficiency was reduced. To preserve both gene transfer ability and biocompatibility, EDTA was applied to remove calcium ions for loosening alginate fiber structure. This treatment may initially maintain alginate fibers for nanoparticle adsorption, but these alginate fibers were gradually degraded in days to create a more appropriate environment for cell survival. For clinical application, we tried to regulate calcium concentration during fiber crosslinking to control the stability of alginate fibers. Though decreasing the levels of crosslinking, alginate fibers were degraded with time, which promoted both transfection efficiency and biocompatibility. These results supported biodegradable composite scaffolds should be potential for drug delivery with excellent bioactivity, which should be beneficial for tissue engineering applications.
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Liao, Yu Han, et 廖于涵. « Preparation and Photocatalysis of TiO2/Cellulose Nanofibers Composite Films ». Thesis, 2018. http://ndltd.ncl.edu.tw/handle/3y2t2u.
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Cheng-ChiaChen et 陳政佳. « Electrospun polyethylene and its composite nanofibers and its property characterization ». Thesis, 2012. http://ndltd.ncl.edu.tw/handle/18322187224754108310.
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碩士國立成功大學
化學工程學系碩博士班
100
High-temperature solution electrospinning was carried out to prepare nano-fibers of metallocene-based polyethylene (mPE). The effect of different processing variables, i.e. flow rate (Q), solution viscosity, circulating oil temperature (Toil) on the Taylor cone, jet length, jet diameter (dj), fiber diameter (df) were investigated. The scaling laws for the mPE solution electrospinning were discovered. The fiber diameter was decreased with increasing Toil. Based on our findings, a stable process and bead-free fibers could be obtained by electrospinning of 8 wt% mPE solutions. The polymer concentration of 8 wt% mPE solution was fixed to make a further study of electrospinning of polymer blend solutions, i.e. mPE/UHMWPE, mPE/graphene solutions. Due to the formation of gel, neat UHMWPE solutions would block the spinneret during electrospinning, and the electrospinning of UHMWPE solutions was not a continuous process. The addition of mPE in UHMWPE solution could suppress the gel formation of UHMWPE and a stable electrospinning process of mPE/UHMWPE solution could be attained. Thinner fibers were produced by electrospinning of mPE/graphene solutions because the solution conductivity was increased by adding graphene. The dispersion of graphene in the mPE fibers was not well so that the conductivity of composite fibers was not obviously improved although 0.5 wt% graphene was added. The mechanical properties of different composite fibers were measured by an universal tensile testing machine. From the stress-strain curves of fiber mats, mPE/graphene composite fibers had the largest Young’s modulus and neat mPE fibers had the highest toughness. According to the cyclic tensile test, neat mPE fibers had good elasticity which was similar to rubbers.
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Chang, Yin Hsin, et 張尹馨. « Composite electrospun nanofibers of polycaprolactone and nanohydroxyapatite for bone tissue engineering ». Thesis, 2009. http://ndltd.ncl.edu.tw/handle/27327035137698947061.
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碩士長庚大學
生化與生醫工程研究所
97
This research uses the electrospinning technology to prepare polycaprolactone / nanohydroxyapatite nanofibrous membranes. Nanofibrous membranes prepared will have high porosity and specific surface area. The main operation parameters include : the polymer concentration, intensity of electric field, the distance from syringe needle to collector, flow rate and working temperature. The research cited references to synthesize nanohydroxyapatite, and studied for electrospinning parameters to the membranes of different diameter and content nHAP. After the composite membranes were subject to detailed analysis by scanning electron microscopy / energy –dispersive X-ray spectrometer, field emission scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, tensile testing and Thermogravimetric Analyzer. In vitro, electrospun nanofibers membrane for bone tissue engineering. The preliminary results show in different diameter, 100 nm and 300 nm provide MSC suitable growth environment. And in different nHAP content condition, can be applied as a suitable 3-D scaffold for cultivation of MSCs and show a promising potential for applications of bone regeneration.
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Lin, Cheng-Hsien, et 林政賢. « Electrospinning of Polycaprolactone/Alginate Composite Nanofibers for Cancer Stem Cell Enrichment ». Thesis, 2016. http://ndltd.ncl.edu.tw/handle/7j67u3.
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碩士國立中央大學
化學工程與材料工程學系
104
Although electrospun alginate scaffolds can be used to enrich cancer cells with high drug resistance, the low cell adhesion and proliferation restricts its application. Therefore, we incorporated polycaprolactone (PCL) for coelectrospinning to prepare composite nanofibrous scaffolds. The composition of nanofibers can be regulated through adjusting the perfusion rates of polymer jets. These composite scaffolds were applied to culture cancer cell lines. The enriched cells were treated anti-cancer drug to evaluate their drug resistances. The results suggested that the drug resistance of cells selected from composite scaffolds was similar to those from alginate fibers. However, their adhesion and proliferation were highly improved. We applied qPCR to analyzed gene expression of selected cells, and the results demonstrated that cell collected from alginate and composite fibers all exhibited high stemness, invasion, chemical resistance, epithelial-mesenchymal transition, and angiogenesis compared to those on PCL fibers, suggesting these cells should be cancer stem cells. Furthermore, the data of wound healing, colony forming, and cell invasion experiments were also consistence to the qPCR results that alginate and composite fibers can enrich cells exhibiting high cancer-stem-cell properties. These results indicated that cancer stem cell enrichment through composite nanofibrous scaffolds should be beneficial to anti-cancer drug development and the research of cancer therapy.
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I-HanChen et 陳奕瀚. « Fabrication and Characterization of Carbon Nanofibers Composite by the Novel Electrospinning ». Thesis, 2011. http://ndltd.ncl.edu.tw/handle/42551674717225197104.
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Mashao, Gloria. « Polyaniline-zeolitic imidazolate framework composite nanofibers for hydrogen gas sensing application ». Thesis, 2019. http://hdl.handle.net/10386/3149.
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Thesis(M.Sc.(Chemistry)) -- University of Limpopo, 2019The quest for renewable, sustainable and environmentally compatible energy sources have been on-going for decades. Green technology such as hydrogen fuel cell has attained much attention as an alternative energy carrier to carbon-based fuels owing to its renewability and cleanliness. However, hydrogen gas feed to the fuel cell can easily be ignited if its concentration is above 4 wt.% at room temperature. Thus, hydrogen safety mechanisms such as hydrogen sensors are vital to guarantee people‘s safety in the hydrogen infrastructure. Sensors based on metals and metal oxides have been widely applied for hydrogen gas detection. Nonetheless, these materials are only sensitive to hydrogen gas at elevated temperatures (˃ 100 °C) and they also possess low surface area (< 20 m2/g). Hence in this work, we present polyaniline (PANI) doped with cobalt-based zeolitic benzimidazolate framework (CoZIF) and zinc-ZIF to fabricate (PANI-CoZIF and PANIZnZIF) composite nanofibers as effective electrocatalysts for hydrogen gas sensing application. The composites were synthesised through chemical oxidative polymerisation of aniline monomer in the presence of 3.6 wt.% CoZIF and ZnZIF, respectively. The structural properties of the synthesised materials were studied using Ultraviolet visible (UV-vis), X-ray diffraction (XRD), Fourier transform infrared (FTIR), Raman spectroscopy and simultaneous thermal analysis (STA). FTIR, Raman and XRD studies showed successful synthesis of CoZIF, ZnZIF and their composites. Furthermore, the studies indicated the co-existence of both CoZIF and ZnZIF in the PANI matrix upon composites formation, indicated by reduction in crystalline size, decrease in band gap and increase in thermal stability. as compared to the neat PANI. Morphological characteristics of the prepared samples were investigated usingscanning electron microscopy (SEM) and transmission electron microscopy (TEM) coupled with both energy dispersive spectroscopy and X-ray (EDS/EDX). PANICoZIF revealed the grafting of CoZIF on to the surface of PANI matrix while PANI-ZnZIF composite showed that PANI is wrapping the cube nanofiber-like structures of ZnZIF also supported by selected area electron diffraction (SAED). Cyclic voltammetry (CV), Tafel analysis and turn over frequencies (TOFs) were performed to study the electrochemical performance of the synthesised materials through hydrogen evolution reaction (HER) for gas sensing. Both composites presented drastic enhancement in the catalytic H2 evolution at 0.033 mol.L-1 H2SO4 with the Tafel slope of 160 mV/dec and exchange current density of 3.98 A.m-2 for PANI-CoZIF composite, while the Tafel slope and exchange current density for PANIZnZIF composite were 246 mV/dec and 5.01 A.m-2, respectively. Moreover, the TOFs of the PANI-CoZIF composite (0,117 mol H2.s-1) was higher as compared to neat PANI (0.040 mol H2.s-1). The TOF values for PANI and PANI-ZnZIF composite were 0.04 and 0.45 mol H2.s-1, respectively. In addition, the chronoamperometric (CA) results exhibited the significant improvement in the electrochemical hydrogen sensing ability of PANI-CoZIF and PANI-ZnZIF composites with higher current response and sensitivity values of 12 and 10.8 µA.mmol.L-1 H2, respectively. The composites exhibited faster steady state response time of 5 s for PANI-CoZIF composite and 4 s for PANI-ZnZIF composite accompanied by lower detection limit (5.27 µmol.L-1) as compared to the neat PANI matrix. The high electrochemical current response is due to extraordinary specific surface area, more accessible active sites available for the electrolyte provided by CoZIF and ZnZIF and high conductivity supplied by PANI. These results proved that the PANI-CoZIF and PANI- ZnZIF composites are suitable electrocatalytic materials for hydrogen gas sensing application through HER in acidic medium. These results further suggest that the safety of people in mining sectors and other industries can be addressed through simple electrocatalytic gas sensing systems.