Microstructure and Mechanical Properties of Polyacrylonitrile Precursor Fiber with Dry and Wet Drawing Process

Polyacrylonitrile (PAN) fibers are typically used as precursor fibers for carbon fiber production, produced through wet-spinning processes. The drawing process of the spun fiber can be classified into dry and wet drawing processes. It is known that the drawing stability and stretching ratio differ depending on the drawing process; however, the elementary characteristics are approximately similar. In this study, the mechanical properties of PAN fibers have been examined based on these two drawing processes with the differences analyzed through the analysis of microstructures. Further, to examine the composition of the fiber, element analysis has been conducted, and thereafter, the microstructure of the fiber is examined through X-ray diffraction analysis. Finally, the characteristics of PAN fibers and its mechanical properties has been examined according to each drawing condition. There are differences in moisture content and microstructure according to the drawing process, and it affects the tensile behavior. The results obtained could have potential implications if the processes are combined, as it could result in a design for a stable and highly efficient drawing process.

Download Full-text

Effect of Processing Conditions on Properties of KMnO4-Treated PAN Fibers

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.821-822.23 ◽

2013 ◽

Vol 821-822 ◽

pp. 23-27

Author(s):

Xiang Li ◽

Chun Yi Liu ◽

Ai Wen Qin ◽

Xin Zhen Zhao ◽

Chun Ju He

Keyword(s):

Mechanical Properties ◽

Aqueous Solution ◽

Chemical Structure ◽

Suitable Condition ◽

Wide Angle ◽

Processing Conditions ◽

X Ray Diffraction ◽

X Ray ◽

Scanning Electron ◽

Pan Fibers

Plasticized polyacrylonitrile(PAN) fibers have been chemically impregnated with aqueous solution of KMnO4under varying conditions of temperature and time. The effect of modification conditions on the chemical structure and the mechanical properties of precursor fibers are characterized by wide-angle X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscope. The experimental results show that KMnO4can be used not only as catalyst for cyclization reaction, but also as plasticizer. The chemical modification between KMnO4and PAN can not occur below70°C, the most suitable condition for modification is performed at 80°C for 5 min.

Download Full-text

Effect of a Multiple Reduction Die on the Residual Stress of Drawn Materials

Materials ◽

10.3390/ma14061358 ◽

2021 ◽

Vol 14 (6) ◽

pp. 1358

Author(s):

Jeong-Hun Kim ◽

Chang-Hyun Baek ◽

Sang-Kon Lee ◽

Jong-Hun Kang ◽

Joon-Hong Park ◽

...

Keyword(s):

Neural Network ◽

Residual Stress ◽

Finite Element Analysis ◽

Finite Element ◽

Residual Stresses ◽

Deep Neural Network ◽

Drawing Process ◽

X Ray Diffraction ◽

Element Analysis ◽

X Ray

Residual stress may influence the mechanical behavior and durability of drawn materials. Thus, this study develops a multiple reduction die (MRD) that can reduce residual stress during the drawing process. The MRD set consists of several die tips, die cases, and lubricating equipment. All the die tips of the MRD were disposed of simultaneously. Finite element analysis of the drawing process was performed according to the reduction ratio of each die tip, and the variables in drawing process with the MRD were optimized using a deep neural network to minimize the residual stress. Experiments on the drawing process with the conventional die and MRD were performed to evaluate the residual stress and verify the effectiveness of the MRD. The results of X-ray diffraction measurements indicated that the axial and hoop residual stresses on the surface were dramatically reduced.

Download Full-text

Effect of Different Pressures of Supercritical Carbon Dioxide on the Microstructure of PAN Fibers during the Hot-Drawing Process

Polymers ◽

10.3390/polym11030403 ◽

2019 ◽

Vol 11 (3) ◽

pp. 403 ◽

Cited By ~ 4

Author(s):

Mengmeng Qiao ◽

Haijuan Kong ◽

Xiaoma Ding ◽

Zhifeng Hu ◽

Luwei Zhang ◽

...

Keyword(s):

Mechanical Properties ◽

Carbon Dioxide ◽

Supercritical Carbon Dioxide ◽

Strength Analysis ◽

Drawing Process ◽

X Ray ◽

Degree Of Orientation ◽

Hot Drawing ◽

Pan Fibers ◽

Supercritical Carbon

The hot-drawing process of polyacrylonitrile (PAN) fibers is an important step during the production of PAN-based carbon fibers. In this study, supercritical carbon dioxide (Sc-CO2) was used as one kind of media for thermal stretching of PAN fibers to study the effect of different pressures of Sc-CO2 on crystallinity, degree of orientation and mechanical property of PAN fibers during the hot-drawing process. The changes of microstructure and mechanical properties in the PAN fibers were investigated by wide-angle X-ray diffraction, small angle X-ray scattering and monofilament strength analysis. The results showed that as the pressure increased, the crystallinity and degree of orientation of PAN fibers increased. Furthermore, when the pressure was 10 MPa, the crystallinity increased from 69.78% to 79.99%, which was the maximum crystallinity among the different pressures. However, when the pressure was further increased, the crystallinity and degree of orientation of the fibers were reduced. The test results of the mechanical properties were consistent with the trends of crystallinity and degree of orientation, showing that when the pressure was 10 MPa, the tensile strength of the fibers increased from 4.59 cN·dtex−1 to 7.06 cN·dtex−1 and the modulus increased from 101.54 cN·dtex−1 to 129.55 cN·dtex−1.

Download Full-text

Study of Texture and Recrystallization in Wire Steel

Materials Science Forum ◽

10.4028/www.scientific.net/msf.467-470.235 ◽

2004 ◽

Vol 467-470 ◽

pp. 235-240 ◽

Cited By ~ 3

Author(s):

Zakaria Boumerzoug ◽

N. Lahraki ◽

Mosbah Zidani

Keyword(s):

Mechanical Properties ◽

Wire Diameter ◽

Drawing Process ◽

X Ray Diffraction ◽

X Ray ◽

Metal Plasticity ◽

Annealing Temperatures ◽

External Stresses ◽

Wire Steel ◽

Scanning Electron

The operation which allows reducing wire diameter is called wiredrawing. The wiredrawing principle is that of using the metal plasticity to reduce the wire diameter. Our study is based on wire steel containing 0.05 % carbon. The regular orientation of the grains (texture) caused by external stresses during the drawing process is observed. This texture causes a phenomenon of material consolidation. Two annealing temperatures were applied on deformed wires for modifying the structure and mechanical properties. The effects of drawing and thermal treatment on our material were studied by, scanning electron microscope, hardness measurements and X – ray diffraction.

Download Full-text

Mechanical properties of FeAlSi powders prepared by mechanical alloying from different initial feedstock materials

Matériaux & Techniques ◽

10.1051/mattech/2018063 ◽

2019 ◽

Vol 107 (2) ◽

pp. 207 ◽

Cited By ~ 2

Author(s):

Jaroslav Čech ◽

Petr Haušild ◽

Miroslav Karlík ◽

Veronika Kadlecová ◽

Jiří Čapek ◽

...

Keyword(s):

Mechanical Properties ◽

Mechanical Alloying ◽

Young’S Modulus ◽

Milling Time ◽

Young's Modulus ◽

Element Model ◽

X Ray Diffraction ◽

X Ray ◽

Powder Particles ◽

Complete Homogenization

FeAl20Si20 (wt.%) powders prepared by mechanical alloying from different initial feedstock materials (Fe, Al, Si, FeAl27) were investigated in this study. Scanning electron microscopy, X-ray diffraction and nanoindentation techniques were used to analyze microstructure, phase composition and mechanical properties (hardness and Young’s modulus). Finite element model was developed to account for the decrease in measured values of mechanical properties of powder particles with increasing penetration depth caused by surrounding soft resin used for embedding powder particles. Progressive homogenization of the powders’ microstructure and an increase of hardness and Young’s modulus with milling time were observed and the time for complete homogenization was estimated.

Download Full-text

Enhancement of Chloroprene/Natural/Butadiene Rubber Nanocomposite Properties Using Organoclays and Their Combination with Carbon Black as Fillers

Polymers ◽

10.3390/polym13071085 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1085

Author(s):

Patricia Castaño-Rivera ◽

Isabel Calle-Holguín ◽

Johanna Castaño ◽

Gustavo Cabrera-Barjas ◽

Karen Galvez-Garrido ◽

...

Keyword(s):

Mechanical Properties ◽

Carbon Black ◽

High Performance ◽

Rubber Matrix ◽

Butadiene Rubber ◽

X Ray Diffraction ◽

X Ray ◽

Rubber Blends ◽

Ft Ir ◽

Chloroprene Rubber

Organoclay nanoparticles (Cloisite® C10A, Cloisite® C15) and their combination with carbon black (N330) were studied as fillers in chloroprene/natural/butadiene rubber blends to prepare nanocomposites. The effect of filler type and load on the physical mechanical properties of nanocomposites was determined and correlated with its structure, compatibility and cure properties using Fourier Transformed Infrared (FT-IR), X-ray Diffraction (XRD), Thermogravimetric Analysis (TGA) and rheometric analysis. Physical mechanical properties were improved by organoclays at 5–7 phr. Nanocomposites with organoclays exhibited a remarkable increase up to 46% in abrasion resistance. The improvement in properties was attributed to good organoclay dispersion in the rubber matrix and to the compatibility between them and the chloroprene rubber. Carbon black at a 40 phr load was not the optimal concentration to interact with organoclays. The present study confirmed that organoclays can be a reinforcing filler for high performance applications in rubber nanocomposites.

Download Full-text

The Potential for Natural Stones from Northeastern Brazil to Be Used in Civil Construction

Minerals ◽

10.3390/min11050440 ◽

2021 ◽

Vol 11 (5) ◽

pp. 440

Author(s):

Fabiana Pereira da Costa ◽

Jucielle Veras Fernandes ◽

Luiz Ronaldo Lisboa de Melo ◽

Alisson Mendes Rodrigues ◽

Romualdo Rodrigues Menezes ◽

...

Keyword(s):

Mechanical Properties ◽

Thermal Analysis ◽

Differential Thermal Analysis ◽

Chemical Resistance ◽

Mechanical Analysis ◽

Northeastern Brazil ◽

X Ray Diffraction ◽

X Ray ◽

Chemical Agents ◽

Natural Stones

Natural stones (limestones, granites, and marble) from mines located in northeastern Brazil were investigated to discover their potential for use in civil construction. The natural stones were characterized by chemical analysis, X-ray diffraction, differential thermal analysis, and optical microscopy. The physical-mechanical properties (apparent density, porosity, water absorption, compressive and flexural strength, impact, and abrasion) and chemical resistance properties were also evaluated. The results of the physical-mechanical analysis indicated that the natural stones investigated have the potential to be used in different environments (interior, exterior), taking into account factors such as people’s circulation and exposure to chemical agents.

Download Full-text

Functional Bionanocomposite Fibers of Chitosan Filled with Cellulose Nanofibers Obtained by Gel Spinning

Polymers ◽

10.3390/polym13101563 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1563

Author(s):

Sofia Marquez-Bravo ◽

Ingo Doench ◽

Pamela Molina ◽

Flor Estefany Bentley ◽

Arnaud Kamdem Tamo ◽

...

Keyword(s):

Mechanical Properties ◽

Mechanical Performance ◽

Cellulose Nanofibers ◽

Microstructural Characterization ◽

Fiber Formation ◽

Fiber Direction ◽

Composite Fibers ◽

X Ray Diffraction ◽

Gel Spinning ◽

X Ray

Extremely high mechanical performance spun bionanocomposite fibers of chitosan (CHI), and cellulose nanofibers (CNFs) were successfully achieved by gel spinning of CHI aqueous viscous formulations filled with CNFs. The microstructural characterization of the fibers by X-ray diffraction revealed the crystallization of the CHI polymer chains into anhydrous chitosan allomorph. The spinning process combining acidic–basic–neutralization–stretching–drying steps allowed obtaining CHI/CNF composite fibers of high crystallinity, with enhanced effect at incorporating the CNFs. Chitosan crystallization seems to be promoted by the presence of cellulose nanofibers, serving as nucleation sites for the growing of CHI crystals. Moreover, the preferential orientation of both CNFs and CHI crystals along the spun fiber direction was revealed in the two-dimensional X-ray diffraction patterns. By increasing the CNF amount up to the optimum concentration of 0.4 wt % in the viscous CHI/CNF collodion, Young’s modulus of the spun fibers significantly increased up to 8 GPa. Similarly, the stress at break and the yield stress drastically increased from 115 to 163 MPa, and from 67 to 119 MPa, respectively, by adding only 0.4 wt % of CNFs into a collodion solution containing 4 wt % of chitosan. The toughness of the CHI-based fibers thereby increased from 5 to 9 MJ.m−3. For higher CNFs contents like 0.5 wt %, the high mechanical performance of the CHI/CNF composite fibers was still observed, but with a slight worsening of the mechanical parameters, which may be related to a minor disruption of the CHI matrix hydrogel network constituting the collodion and gel fiber, as precursor state for the dry fiber formation. Finally, the rheological behavior observed for the different CHI/CNF viscous collodions and the obtained structural, thermal and mechanical properties results revealed an optimum matrix/filler compatibility and interface when adding 0.4 wt % of nanofibrillated cellulose (CNF) into 4 wt % CHI formulations, yielding functional bionanocomposite fibers of outstanding mechanical properties.

Download Full-text

The crystal structures and mechanical properties of the uranyl carbonate minerals roubaultite, fontanite, sharpite, widenmannite, grimselite and čejkaite

Inorganic Chemistry Frontiers ◽

10.1039/d0qi00933d ◽

2020 ◽

Vol 7 (21) ◽

pp. 4197-4221 ◽

Cited By ~ 1

Author(s):

Francisco Colmenero ◽

Jakub Plášil ◽

Jiří Sejkora

Keyword(s):

Mechanical Properties ◽

Hydrogen Bonding ◽

Diffraction Pattern ◽

Crystal Structures ◽

First Principles ◽

X Ray Diffraction ◽

Carbonate Minerals ◽

X Ray ◽

Uranyl Carbonate

The structure, hydrogen bonding, X-ray diffraction pattern and mechanical properties of six important uranyl carbonate minerals, roubaultite, fontanite, sharpite, widenmannite, grimselite and čejkaite, are determined using first principles methods.

Download Full-text

Effects of Sintering Temperature on Densification, Microstructure and Mechanical Properties of Al-Based Alloy by High-Velocity Compaction

Metals ◽

10.3390/met11020218 ◽

2021 ◽

Vol 11 (2) ◽

pp. 218

Author(s):

Xianjie Yuan ◽

Xuanhui Qu ◽

Haiqing Yin ◽

Zaiqiang Feng ◽

Mingqi Tang ◽

...

Keyword(s):

Mechanical Properties ◽

High Velocity ◽

Sintered Density ◽

Sintering Temperature ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

X Ray ◽

Transmission Electron ◽

High Velocity Compaction ◽

Sintered Temperature

This present work investigates the effects of sintering temperature on densification, mechanical properties and microstructure of Al-based alloy pressed by high-velocity compaction. The green samples were heated under the flow of high pure (99.99 wt%) N2. The heating rate was 4 °C/min before 315 °C. For reducing the residual stress, the samples were isothermally held for one h. Then, the specimens were respectively heated at the rate of 10 °C/min to the temperature between 540 °C and 700 °C, held for one h, and then furnace-cooled to the room temperature. Results indicate that when the sintered temperature was 640 °C, both the sintered density and mechanical properties was optimum. Differential Scanning Calorimetry, X-ray diffraction of sintered samples, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, and Transmission Electron Microscope were used to analyse the microstructure and phases.

Download Full-text