Theory and Simulation of Texture Formation in Mesophase Carbon Fibers

ABSTRACTCarbonaceous mesophases are spun into high performance carbon fibers using the melt spinning process. The spinning process produces a range of fiber textures whose origins are not well understood. Planar polar (PP) and planar radial (PR) textures are two ubiquitous ones. A model that describes the formation process of the PP texture based on the Landau-de Gennes mesoscopic theory for discotic liquid crystals, including defect nucleation, defect migration, and overall texture geometry, is presented, solved, and validated. The computed PP and PR textures phase diagram, given in terms of temperature and fiber radius, is presented to establish the processing conditions and geometric factors that lead to the selection of these textures. The influence of elastic anisotropy to the textures formation and structure is also characterized.

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The Effect of External Magnetic Field on Microstructure and Magnetic Properties of Melt-Spun Nd-Fe-B/Fe-Co Nanocomposite Ribbons

Advances in Materials Science and Engineering ◽

10.1155/2013/927356 ◽

2013 ◽

Vol 2013 ◽

pp. 1-5 ◽

Cited By ~ 2

Author(s):

Xuan Truong Nguyen ◽

Hong Ky Vu ◽

Hung Manh Do ◽

Van Khanh Nguyen ◽

Van Vuong Nguyen

Keyword(s):

Magnetic Field ◽

Grain Size ◽

High Performance ◽

Melt Spinning ◽

Nominal Composition ◽

Energy Product ◽

Melt Spun ◽

Spinning Process ◽

Reduction Effect ◽

Microstructure And Magnetic Properties

The ribbons Nd2Fe14B/Fe-Co were prepared with the nominal composition Nd16Fe76B8/40% wt. Fe65Co35by the conventional and the developed magnetic field-assisted melt-spinning (MFMS) techniques. Both ribbons are nanocomposites with the smooth single-phase-like magnetization loops. The 0.32 T magnetic field perpendicular to the wheel surface and assisting the melt-spinning process reduces the grain size inside the ribbon, increases the texture of the ribbon, improves the exchange coupling, and, in sequence, increases the energy product(BH)maxof the isotropic powdered samples of MFMS ribbon in ~9% by comparison with that of the ribbon melt-spun conventionally. The grain size reduction effect caused by the assisted magnetic field has also been described quantitatively. The MFMS technique seems to be promising for producing high-performance nanocomposite ribbons.

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Theory and Simulation of Fiber Texture Formation and Rheology of Carbonaceous Mesophase Fibers

MRS Proceedings ◽

10.1557/proc-709-cc8.5.1 ◽

2001 ◽

Vol 709 ◽

Author(s):

A. D. Rey

Keyword(s):

Liquid Crystals ◽

High Performance ◽

Melt Spinning ◽

Elongational Flow ◽

Fiber Texture ◽

Texture Formation ◽

Cross Sectional ◽

Wide Range ◽

Spinning Process ◽

Sectional Shape

ABSTRACTCarbonaceous mesophases are discotic nematic liquid crystals that are spun into high performance carbon fibers using the melt spinning process. The spinning process produces a wide range of different fiber textures and cross-sectional shapes. Circular planar polar (PP), circular planar radial (PR) textures, ribbon planar radial (RPR), and ribbon planar line (RPL) textures are ubiquitous ones. This paper presents, solves, and validates a model of mesophase fiber texture formation based on the classical Landau-de Gennes theory of liquid crystals, adapted here to carbonaceous mesophases. The effects of fiber cross-sectional shape and elongational flow on texture formation are characterized. Emphasis is on qualitative model validation using existing experimental data [1, 2]. The results provide additional knowledge on how to optimize and control mesophase fiber textures.

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Microstructure Evolution and Mechanical Properties of Melt Spun Skutterudite-based Thermoelectric Materials

Materials ◽

10.3390/ma13040984 ◽

2020 ◽

Vol 13 (4) ◽

pp. 984 ◽

Cited By ~ 3

Author(s):

Huiyuan Geng ◽

Jialun Zhang ◽

Tianhong He ◽

Lixia Zhang ◽

Jicai Feng

Keyword(s):

Mechanical Properties ◽

Spinodal Decomposition ◽

Microstructure Evolution ◽

Thermoelectric Materials ◽

High Performance ◽

Melt Spinning ◽

Bending Strength ◽

Annealed Sample ◽

Submicron Scale ◽

Spinning Process

The rapid solidification of melt spinning has been widely used in the fabrication of high-performance skutterudite thermoelectric materials. However, the microstructure formation mechanism of the spun ribbon and its effects on the mechanical properties are still unclear. Here, we report the microstructure evolution and mechanical properties of La–Fe–Co–Sb skutterudite alloys fabricated by both long-term annealing and melt-spinning, followed by sintering approaches. It was found that the skutterudite phase nucleated directly from the under-cooled melt and grew into submicron dendrites during the melt-spinning process. Upon heating, the spun ribbons started to form nanoscale La-rich and La-poor skutterudite phases through spinodal decomposition at temperatures as low as 473 K. The coexistence of the micron-scale grain size, the submicron-scale dendrite segregation and the nanoscale spinodal decomposition leads to high thermoelectric performance and mechanical strength. The maximum three-point bending strength of the melt spinning sample was about 195 MPa, which was 70% higher than that of the annealed sample.

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Transient Confinement of the Quaternary Tetramethylammonium Tetrafluoroborate Salt in Nylon 6,6 Fibres: Structural Developments for High Performance Properties

Materials ◽

10.3390/ma14112938 ◽

2021 ◽

Vol 14 (11) ◽

pp. 2938

Author(s):

Ahmed Dawelbeit ◽

Muhuo Yu

Keyword(s):

Phase Transitions ◽

High Performance ◽

Melt Spinning ◽

Structural Phase ◽

Tensile Modulus ◽

High Strength ◽

Strength Properties ◽

Nylon 6,6 ◽

Spinning Process ◽

Hot Drawing

A temporary confinement of the quaternary tetramethylammonium tetrafluoroborate (TMA BF4) salt among polyamide molecules has been used for the preparation of aliphatic polyamide nylon 6,6 fibres with high-modulus and high-strength properties. In this method, the suppression or the weakening of the hydrogen bonds between the nylon 6,6 segments has been applied during the conventional low-speed melt spinning process. Thereafter, after the complete hot-drawing stage, the quaternary ammonium salt is fully extracted from the drawn 3 wt.% salt-confined fibres and the nascent fibres are, subsequently, thermally stabilized. The structural developments that are acquired in the confined-nylon 6,6 fibres are ascribed to the developments of the overall fibres’ properties due to the confinement process. Surprisingly, unlike the neat nylon 6,6 fibres, the X-ray diffraction (XRD) patterns of the as-spun salt-confined fibres have shown diminishing of the (110)/(010) diffraction plane that obtained pseudohexagonal-like β’ structural phase. Moreover, the β’ pseudohexagonal-like to α triclinic phase transitions took-place due to the hot-drawing stage (draw-induced phase transitions). Interestingly, the hot-drawing of the as-spun salt-confined nylon 6,6 fibres achieved the same maximum draw ratio of 5.5 at all of the drawing temperatures of 120, 140 and 160 °C. The developments that happened produced the improved values of 43.32 cN/dtex for the tensile-modulus and 6.99 cN/dtex for the tensile-strength of the reverted fibres. The influences of the TMA BF4 salt on the structural developments of the crystal orientations, on the morphological structures and on the improvements of the tensile properties of the nylon 6,6 fibres have been intensively studied.

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Rheology of Polyacrylonitrile/Lignin Blends in Ionic Liquids under Melt Spinning Conditions

Molecules ◽

10.3390/molecules24142650 ◽

2019 ◽

Vol 24 (14) ◽

pp. 2650 ◽

Cited By ~ 1

Author(s):

Jinxue Jiang ◽

Keerthi Srinivas ◽

Alper Kiziltas ◽

Andrew Geda ◽

Birgitte K. Ahring

Keyword(s):

Carbon Fiber ◽

Carbon Fibers ◽

Melt Spinning ◽

Lower Cost ◽

Biomass Pretreatment ◽

Limited Success ◽

Spinning Process ◽

Physical Interactions ◽

Butyric Anhydride ◽

Newtonian Behavior

Lignin, while economically and environmentally beneficial, has had limited success in use in reinforcing carbon fibers due to harmful chemicals used in biomass pretreatment along with the limited physical interactions between lignin and polyacrylonitrile (PAN) during the spinning process. The focus of this study is to use lignin obtained from chemical-free oxidative biomass pretreatment (WEx) for blending with PAN at melt spinning conditions to produce carbon fiber precursors. In this study, the dynamic rheology of blending PAN with biorefinery lignin obtained from the WEx process is investigated with the addition of 1-butyl-3-methylimidazolium chloride as a plasticizer to address the current barriers of developing PAN/lignin carbon fiber precursors in the melt-spinning process. Lignin was esterified using butyric anhydride to reduce its hydrophilicity and to enhance its interactions with PAN. The studies indicate that butyration of the lignin (BL) increased non-Newtonian behavior and decreased thermo-reversibility of blends. The slope of the Han plot was found to be around 1.47 for PAN at 150 °C and decreased with increasing lignin concentrations as well as temperature. However, these blends were found to have higher elasticity and solution yield stress (47.6 Pa at 20%wt BL and 190 °C) when compared to pure PAN (5.8 Pa at 190 °C). The results from this study are significant for understanding lignin–PAN interactions during melt spinning for lower-cost carbon fibers.

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Study on strong spinning preparation method and mechanism of the industrial pure titanium ultrafine crystallization

Journal of Engineered Fibers and Fabrics ◽

10.1177/1558925019895256 ◽

2019 ◽

Vol 14 ◽

pp. 155892501989525

Author(s):

Yu Yang ◽

Yanyan Jia

Keyword(s):

Heat Treatment ◽

High Performance ◽

Pure Titanium ◽

Grain Structure ◽

Theoretical Research ◽

Ultrafine Grain ◽

Forming Process ◽

Spinning Process ◽

And Performance ◽

Material Utilization

Ultrafine crystallization of industrial pure titanium allowed for higher tensile strength, corrosion resistance, and thermal stability and is therefore widely used in medical instrumentation, aerospace, and passenger vehicle manufacturing. However, the ultrafine crystallizing batch preparation of tubular industrial pure titanium is limited by the development of the spinning process and has remained at the theoretical research stage. In this article, the tubular TA2 industrial pure titanium was taken as the research object, and the ultrafine crystal forming process based on “5-pass strong spin-heat treatment-3 pass-spreading-heat treatment” was proposed. Based on the spinning process test, the ultimate thinning rate of the method is explored and the evolution of the surface microstructure was analyzed by metallographic microscope. The research suggests that the multi-pass, medium–small, and thinning amount of spinning causes the grain structure to be elongated in the axial and tangential directions, and then refined, and the axial fiber uniformity is improved. The research results have certain scientific significance for reducing the consumption of high-performance metals improving material utilization and performance, which also promote the development of ultrafine-grain metals’ preparation technology.

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Selection of Insulating Elastomers for High-Performance Intrinsically Stretchable Transistors

ACS Applied Electronic Materials ◽

10.1021/acsaelm.1c00062 ◽

2021 ◽

Author(s):

Hang Ren ◽

Junmo Zhang ◽

Yanhong Tong ◽

Mingxin Zhang ◽

Xiaoli Zhao ◽

...

Keyword(s):

High Performance ◽

Selection Of

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Realizing Stable High‐Performance and Low‐Energy‐Loss Ternary Photovoltaics through Judicious Selection of the Third Component

Solar RRL ◽

10.1002/solr.202100450 ◽

2021 ◽

pp. 2100450

Author(s):

Bing-Huang Jiang ◽

Yi-Peng Wang ◽

Yu-Wei Su ◽

Jia-Fu Chang ◽

Chu-Chen Chueh ◽

...

Keyword(s):

Energy Loss ◽

High Performance ◽

Low Energy ◽

The Third ◽

Selection Of

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An Overview of Molecular Dynamic Simulation for Corrosion Inhibition of Ferrous Metals

Metals ◽

10.3390/met11010046 ◽

2020 ◽

Vol 11 (1) ◽

pp. 46

Author(s):

Nur Izzah Nabilah Haris ◽

Shafreeza Sobri ◽

Yus Aniza Yusof ◽

Nur Kartinee Kassim

Keyword(s):

Molecular Dynamic ◽

Corrosion Inhibition ◽

High Performance ◽

Md Simulation ◽

Ferrous Metal ◽

Working Mechanism ◽

Inhibitor Molecule ◽

As Adsorption ◽

Inhibition Studies ◽

Selection Of

Molecular dynamics (MD) simulation is a powerful tool to study the molecular level working mechanism of corrosion inhibitors in mitigating corrosion. In the past decades, MD simulation has emerged as an instrument to investigate the interactions at the interface between the inhibitor molecule and the metal surface. Combined with experimental measurement, theoretical examination from MD simulation delivers useful information on the adsorption ability and orientation of the molecule on the surface. It relates the microscopic characteristics to the macroscopic properties which enables researchers to develop high performance inhibitors. Although there has been vast growth in the number of studies that use molecular dynamic evaluation, there is still lack of comprehensive review specifically for corrosion inhibition of organic inhibitors on ferrous metal in acidic solution. Much uncertainty still exists on the approaches and steps in performing MD simulation for corrosion system. This paper reviews the basic principle of MD simulation along with methods, selection of parameters, expected result such as adsorption energy, binding energy and inhibitor orientation, and recent publications in corrosion inhibition studies.

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