In this study, an artificial neural network (ANN) model is presented in order to predict the tena... more In this study, an artificial neural network (ANN) model is presented in order to predict the tenacity and hairiness of carded cotton yarns. Fiber measurement values generated by using a high-volume instrument (HVI) and an advanced fiber information system (AFIS) were used in the ANN model as input parameters. The radial basis function neural network (RBFNN) was used as ANN structure. The best RBFNN model was determined by analyzing the effect of epochs and the number of neurons on prediction performance. By using this ANN structure, the comparison between the performance of predicting yarn properties from HVIs and from AFISs was carried out. In the study, four different yarn counts (Ne20, Ne24, Ne30, and Ne40) for 10 different blends were applied. Each yarn count was spun at 4.34αe twist factor. In this study, the model presented a good rate of accuracy for predicting yarn tenacity and hairiness by using HVI and AFIS fiber values. The study showed that there was no significant difference between the accuracy of predicting these yarn properties from HVI fiber measurement results and those from an AFIS by using the RBF. From the results, it was noted that the performance of predicting yarn hairiness was better than that of predicting yarn tenacity. Also, this study could provide researchers with exclusive information on how to select the most appropriate ANN architecture and how to evolve the model for testing.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
LiFePO4/graphene/C composite nanofibers, in which LiFePO4 nanoparticles were encapsulated in grap... more LiFePO4/graphene/C composite nanofibers, in which LiFePO4 nanoparticles were encapsulated in graphene-containing carbon nanofiber matrix, were synthesized by using a combination of electrospinning and sol-gel techniques. Polyacrylonitrile (PAN) was used as the electrospinning media and the carbon source. Graphene was incorporated in order to increase the conductivity of the composite. PAN was dissolved in N,N–dimethylformamide (DMF). LiFePO4 precursor and graphene were dispersed in DMF separately and were mixed with PAN solution before electrospinning. Electrospun fibers were heat-treated to obtain LiFePO4/graphene/C composite nanofibers. The structure of LiFePO4/graphene/C composite nanofibers was determined by X–ray diffraction analysis. The surface morphology and microstructure of LiFePO4/graphene/C composite nanofibers were characterized using scanning electron microscopy and transmission electron microscopy. Electrochemical performance of LiFePO4/graphene/C composite nanofibers was evaluated in coin-type cells. Graphene flakes were found to be well-dispersed in the carbonaceous matrix and increased the electrochemical performance of the composite nanofibers. As a result, cells containing LiFePO4/graphene/C composite nanofiber cathodes showed good electrochemical performance, in terms of capacity, cycle life, and rate capability.
α-Fe(2)O(3) nanoparticle-loaded carbon nanofiber composites were fabricated via electrospinning F... more α-Fe(2)O(3) nanoparticle-loaded carbon nanofiber composites were fabricated via electrospinning FeCl(3)·6H(2)O salt-polyacrylonitrile precursors in N,N-dimethylformamide solvent and the subsequent carbonization in inert gas. Scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and elemental analysis were used to study the morphology and composition of α-Fe(2)O(3)-carbon nanofiber composites. It was indicated that α-Fe(2)O(3) nanoparticles with an average size of about 20 nm have a homogeneous dispersion along the carbon nanofiber surface. The resultant α-Fe(2)O(3)-carbon nanofiber composites were used directly as the anode material in rechargeable lithium half cells, and their electrochemical performance was evaluated. The results indicated that these α-Fe(2)O(3)-carbon nanofiber composites have high reversible capacity, good capacity retention, and acceptable rate capability when used as anode materials for rechargeable lithium-ion batteries.
International journal of environment and geoinformatics, Mar 7, 2021
Fabrication of sustainable products are of significance from many aspects recently. Industrial he... more Fabrication of sustainable products are of significance from many aspects recently. Industrial hemp as one of the most sustainable, environment friendly plant can be used for many applications. In this study, various sustainable, hemp-derived, binder free, flexible anode materials were prepared by the two-step carbonization method. Plain woven hemp fabric was used as a starting material. Fabrication of hemp-derived anode materials were carried out in two steps known as stabilization and carbonization. While the stabilization step was performed at 220 °C for all samples, carbonization was carried out at 600, 700, 800 and 900 °C in order to optimize the carbonization process. Morphological, electrical and electrochemical characterization of the hemp-based carbon fabric anodes were carried out. Electrical resistance of the hemp-based carbon fabric anodes showed differences depending on the carbonization temperature. Electrochemical results showed that 800 °C is the optimum condition in terms of carbon yield and cell performance if the reversible capacity, cycling stability and rate capability values are considered.
density 1, 2). As an alkali metal, lithium is highly reactive, and hence it is found in nature as... more density 1, 2). As an alkali metal, lithium is highly reactive, and hence it is found in nature as compounds that can be used for different applications, such as pharmacology, aerospace, construction, and energy storage. Rechargeable lithium-ion batteries, which are based on lithium chemistry and were first commercialized by Sony in 1992 3) , are of importance as new generation power sources because they are lighter and have higher energy density, lower self discharge, no memory effect, prolonged service-life, larger number of charge/discharge cycles, better environmental friendliness, and higher safety when compared to
Journal of Solid State Electrochemistry, May 13, 2014
Poly(L-lactic acid-co-succinic acid-co-1,4-butane diol) (PLASB) was synthesized by direct condens... more Poly(L-lactic acid-co-succinic acid-co-1,4-butane diol) (PLASB) was synthesized by direct condensation copolymerization of L-lactic acid (LA), succinic acid (SA), and 1,4-butanediol (BD) in the bulk using titanium(IV) butoxide as a catalyst. The weight-average molecular weight of PLASB was 2.1Ý 10 5 when the contents of SA and BD were each 0.5 mol/100 mol of LA. Electrospinning was used to fabricate porous membranes from this newly synthesized bioabsorbable PLASB dissolved in mixed solvents of methylene chloride and dimethylformamide. Scanning electron microscopy (SEM) images indicated that the fiber diameters and nanostructured morphologies of the electrospun membranes depended on the processing parameters, such as the solvent ratio and the polymer concentration. By adjusting both the solvent mixture ratio and the polymer concentration, we could fabricate uniform nanofiber non-woven membranes. Cell proliferation on the electrospun porous PLASB membranes was evaluated using mouse fibroblast cells; we compare these results with those of the cell responses on bulk PLASB films.
Carbon nanofibers decorated with various amounts of electrochemically-inert metallic nickel nanop... more Carbon nanofibers decorated with various amounts of electrochemically-inert metallic nickel nanoparticles are synthesized through electrospinning and carbonization processes. The morphology and composition of Ni nanoparticles in carbon nanofibers are controlled by preparing different nanofiber precursors. The lithium-ion battery performance evaluations indicated that the content of electrochemically-inert Ni nanoparticles in carbon nanofibers has a great influence on the final electrochemical performance. For example, at certain Ni contents, these composite nanofibers display excellent electrochemical performance, such as high reversible capacities, good capacity retention, and excellent rate performance, when directly used as binder-free anodes for rechargeable lithium-ion batteries. However, when the Ni content is too low or too high, the corresponding electrodes show low reversible capacities although they still have good reversibility and rate performance.
LiFePO4/C composite fibers were synthesized by using a combination of electrospinning and sol–gel... more LiFePO4/C composite fibers were synthesized by using a combination of electrospinning and sol–gel techniques. Polyacrylonitrile (PAN) was used as an electrospinning media and a carbon source. LiFePO4 precursor materials and PAN were dissolved in N,N-dimethylformamide separately and they were mixed before electrospinning. LiFePO4 precursor/PAN fibers were heat treated, during which LiFePO4 precursor transformed to energy-storage LiFePO4 material and PAN was
Since the commercialization of Li-ion batteries by Sony in 1990, the performance of cathode mater... more Since the commercialization of Li-ion batteries by Sony in 1990, the performance of cathode materials used in Li-ion batteries has improved significantly. However, Li-ion batteries cannot respond to the needs of the energy storage market in terms of energy density. In order to increase theoretical energy density of active materials, molar mass of the active material should be decreased, or electron number participating per reaction or reaction potential should be increased. In this study, it was aimed to produce cathode materials for Li-ion batteries in the form of composite nanofibers via electrospinning method. For this purpose, porous LiFexMn1-xPO4/C composite nanofibers (1 > x > 0) were synthesized with a scalable, two-step method (electrospinning and subsequent heat treatment). The morphological, structural and electrochemical properties of the LiFexMn1-xPO4/C composite nanofibers were determined by scanning electron microscope, X-ray diffraction and galvanostatic charge/discharge tests. Cathodes made of LiFexMn1-xPO4/C composite nanofibers showed various advantages such as long cycle life, improved electrochemical performance etc. due to the presence of carbon and LiFexMn1-xPO4 in the composite structure. With the addition of Mn to the structure of LiFePO4/C composite nanofibers, electrochemical performance was improved. LiFe0.8Mn0.2PO4/C composite nanofibers showed the best performance in terms of energy density among the samples. Further increment in Mn/Fe ratio resulted declining electrochemical capacity and energy density.
International journal of environment and geoinformatics, Sep 5, 2021
In this study, activated carbon was produced from platanus orientalis leaves and the adsorption o... more In this study, activated carbon was produced from platanus orientalis leaves and the adsorption of methylene blue onto activated carbon was investigated. Facile chemical activation route was conducted for activation process of lignocellulosic leaves. ZnCl 2 was used as an activating agent at different ratios. Morphological, structural properties and adsorption characteristics of samples were determined by using field emission scanning microscopy, Fourier transform infrared spectroscopy, Braunauer-Emmet-Teller spectroscopy and UV-vis spectroscopy. Surface characterization showed that activation with ZnCl 2 resulted high surface area (~1024 m 2 g-1) and total pore volume (~0.431 cm 3 g-1) compared with crude carbonized leaves samples.
In this study, carbon fibers filled flexible conductive polymer composites were fabricated. Turki... more In this study, carbon fibers filled flexible conductive polymer composites were fabricated. Turkish hemp was used to produce conductive carbon fibers. In order to do this, hemp fibers were carbonized under different conditions. After this step, flexible conductive composites were fabricated by using poly[styrene-b-(ethylene-co-butylene)-b-styrene] matrix and hemp-based carbon fibers. Composite films were produced by combination of solvent casting and hot pressing. Various levels of carbon fibers were used in order to determine the percolation behavior of the composites. Morphological and electrical properties of the composite films were analyzed. Electrical resistivity of the samples decreased by increasing the filler ratio.
Thermoplastic elastomer-based fibers have many advantages including lightness, flexibility, resil... more Thermoplastic elastomer-based fibers have many advantages including lightness, flexibility, resilience. Styrene-[ethylene-(ethylene-propylene)]styrene (SEEPS) is a styrenic block copolymer based thermoplastic elastomer and it can be used for many applications with many functions as a matrix, compatibilizer, modifier or adhesive. It has good resistance to oxidizing agents, weathering, aging, and it can be used under various conditions. In this study, SEEPS block copolymer fibers were electrospun. This study is the first study about the electrospinning of SEEPS block copolymer in the literature. Various spinning solutions were used, and process was optimized by changing the electrospinning conditions. Fiber morphology was analyzed by an optical microscope and fiber diameter distribution histograms were drawn. In order to understand the effects of polymer concentration on electrospinning, viscosity of the spinning solutions was measured. Although electrospinning conditions were found to be critical in terms of spinnability, solution concentration and viscosity were the most significant factors for obtaining flexible SEEPS based fibrous nonwoven mats.
With the rapid development of flexible electronics, conductive textiles are becoming important bu... more With the rapid development of flexible electronics, conductive textiles are becoming important building blocks for wearables in broad applications. Different from conventional textiles, conductive textiles require fabrics to have a basic wearable function as well as electrical conductivity. Conductive textiles have been used in applications such as antistatic, electromagnetic (EM) shielding, and e-textiles. In this chapter, we introduce the fundamental principles of conductive textiles and review recent developments of advanced conductive coating technologies and their applications in antistatic, EM shielding, and e-textiles.
In this study, an artificial neural network (ANN) model is presented in order to predict the tena... more In this study, an artificial neural network (ANN) model is presented in order to predict the tenacity and hairiness of carded cotton yarns. Fiber measurement values generated by using a high-volume instrument (HVI) and an advanced fiber information system (AFIS) were used in the ANN model as input parameters. The radial basis function neural network (RBFNN) was used as ANN structure. The best RBFNN model was determined by analyzing the effect of epochs and the number of neurons on prediction performance. By using this ANN structure, the comparison between the performance of predicting yarn properties from HVIs and from AFISs was carried out. In the study, four different yarn counts (Ne20, Ne24, Ne30, and Ne40) for 10 different blends were applied. Each yarn count was spun at 4.34αe twist factor. In this study, the model presented a good rate of accuracy for predicting yarn tenacity and hairiness by using HVI and AFIS fiber values. The study showed that there was no significant difference between the accuracy of predicting these yarn properties from HVI fiber measurement results and those from an AFIS by using the RBF. From the results, it was noted that the performance of predicting yarn hairiness was better than that of predicting yarn tenacity. Also, this study could provide researchers with exclusive information on how to select the most appropriate ANN architecture and how to evolve the model for testing.
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
LiFePO4/graphene/C composite nanofibers, in which LiFePO4 nanoparticles were encapsulated in grap... more LiFePO4/graphene/C composite nanofibers, in which LiFePO4 nanoparticles were encapsulated in graphene-containing carbon nanofiber matrix, were synthesized by using a combination of electrospinning and sol-gel techniques. Polyacrylonitrile (PAN) was used as the electrospinning media and the carbon source. Graphene was incorporated in order to increase the conductivity of the composite. PAN was dissolved in N,N–dimethylformamide (DMF). LiFePO4 precursor and graphene were dispersed in DMF separately and were mixed with PAN solution before electrospinning. Electrospun fibers were heat-treated to obtain LiFePO4/graphene/C composite nanofibers. The structure of LiFePO4/graphene/C composite nanofibers was determined by X–ray diffraction analysis. The surface morphology and microstructure of LiFePO4/graphene/C composite nanofibers were characterized using scanning electron microscopy and transmission electron microscopy. Electrochemical performance of LiFePO4/graphene/C composite nanofibers was evaluated in coin-type cells. Graphene flakes were found to be well-dispersed in the carbonaceous matrix and increased the electrochemical performance of the composite nanofibers. As a result, cells containing LiFePO4/graphene/C composite nanofiber cathodes showed good electrochemical performance, in terms of capacity, cycle life, and rate capability.
α-Fe(2)O(3) nanoparticle-loaded carbon nanofiber composites were fabricated via electrospinning F... more α-Fe(2)O(3) nanoparticle-loaded carbon nanofiber composites were fabricated via electrospinning FeCl(3)·6H(2)O salt-polyacrylonitrile precursors in N,N-dimethylformamide solvent and the subsequent carbonization in inert gas. Scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and elemental analysis were used to study the morphology and composition of α-Fe(2)O(3)-carbon nanofiber composites. It was indicated that α-Fe(2)O(3) nanoparticles with an average size of about 20 nm have a homogeneous dispersion along the carbon nanofiber surface. The resultant α-Fe(2)O(3)-carbon nanofiber composites were used directly as the anode material in rechargeable lithium half cells, and their electrochemical performance was evaluated. The results indicated that these α-Fe(2)O(3)-carbon nanofiber composites have high reversible capacity, good capacity retention, and acceptable rate capability when used as anode materials for rechargeable lithium-ion batteries.
International journal of environment and geoinformatics, Mar 7, 2021
Fabrication of sustainable products are of significance from many aspects recently. Industrial he... more Fabrication of sustainable products are of significance from many aspects recently. Industrial hemp as one of the most sustainable, environment friendly plant can be used for many applications. In this study, various sustainable, hemp-derived, binder free, flexible anode materials were prepared by the two-step carbonization method. Plain woven hemp fabric was used as a starting material. Fabrication of hemp-derived anode materials were carried out in two steps known as stabilization and carbonization. While the stabilization step was performed at 220 °C for all samples, carbonization was carried out at 600, 700, 800 and 900 °C in order to optimize the carbonization process. Morphological, electrical and electrochemical characterization of the hemp-based carbon fabric anodes were carried out. Electrical resistance of the hemp-based carbon fabric anodes showed differences depending on the carbonization temperature. Electrochemical results showed that 800 °C is the optimum condition in terms of carbon yield and cell performance if the reversible capacity, cycling stability and rate capability values are considered.
density 1, 2). As an alkali metal, lithium is highly reactive, and hence it is found in nature as... more density 1, 2). As an alkali metal, lithium is highly reactive, and hence it is found in nature as compounds that can be used for different applications, such as pharmacology, aerospace, construction, and energy storage. Rechargeable lithium-ion batteries, which are based on lithium chemistry and were first commercialized by Sony in 1992 3) , are of importance as new generation power sources because they are lighter and have higher energy density, lower self discharge, no memory effect, prolonged service-life, larger number of charge/discharge cycles, better environmental friendliness, and higher safety when compared to
Journal of Solid State Electrochemistry, May 13, 2014
Poly(L-lactic acid-co-succinic acid-co-1,4-butane diol) (PLASB) was synthesized by direct condens... more Poly(L-lactic acid-co-succinic acid-co-1,4-butane diol) (PLASB) was synthesized by direct condensation copolymerization of L-lactic acid (LA), succinic acid (SA), and 1,4-butanediol (BD) in the bulk using titanium(IV) butoxide as a catalyst. The weight-average molecular weight of PLASB was 2.1Ý 10 5 when the contents of SA and BD were each 0.5 mol/100 mol of LA. Electrospinning was used to fabricate porous membranes from this newly synthesized bioabsorbable PLASB dissolved in mixed solvents of methylene chloride and dimethylformamide. Scanning electron microscopy (SEM) images indicated that the fiber diameters and nanostructured morphologies of the electrospun membranes depended on the processing parameters, such as the solvent ratio and the polymer concentration. By adjusting both the solvent mixture ratio and the polymer concentration, we could fabricate uniform nanofiber non-woven membranes. Cell proliferation on the electrospun porous PLASB membranes was evaluated using mouse fibroblast cells; we compare these results with those of the cell responses on bulk PLASB films.
Carbon nanofibers decorated with various amounts of electrochemically-inert metallic nickel nanop... more Carbon nanofibers decorated with various amounts of electrochemically-inert metallic nickel nanoparticles are synthesized through electrospinning and carbonization processes. The morphology and composition of Ni nanoparticles in carbon nanofibers are controlled by preparing different nanofiber precursors. The lithium-ion battery performance evaluations indicated that the content of electrochemically-inert Ni nanoparticles in carbon nanofibers has a great influence on the final electrochemical performance. For example, at certain Ni contents, these composite nanofibers display excellent electrochemical performance, such as high reversible capacities, good capacity retention, and excellent rate performance, when directly used as binder-free anodes for rechargeable lithium-ion batteries. However, when the Ni content is too low or too high, the corresponding electrodes show low reversible capacities although they still have good reversibility and rate performance.
LiFePO4/C composite fibers were synthesized by using a combination of electrospinning and sol–gel... more LiFePO4/C composite fibers were synthesized by using a combination of electrospinning and sol–gel techniques. Polyacrylonitrile (PAN) was used as an electrospinning media and a carbon source. LiFePO4 precursor materials and PAN were dissolved in N,N-dimethylformamide separately and they were mixed before electrospinning. LiFePO4 precursor/PAN fibers were heat treated, during which LiFePO4 precursor transformed to energy-storage LiFePO4 material and PAN was
Since the commercialization of Li-ion batteries by Sony in 1990, the performance of cathode mater... more Since the commercialization of Li-ion batteries by Sony in 1990, the performance of cathode materials used in Li-ion batteries has improved significantly. However, Li-ion batteries cannot respond to the needs of the energy storage market in terms of energy density. In order to increase theoretical energy density of active materials, molar mass of the active material should be decreased, or electron number participating per reaction or reaction potential should be increased. In this study, it was aimed to produce cathode materials for Li-ion batteries in the form of composite nanofibers via electrospinning method. For this purpose, porous LiFexMn1-xPO4/C composite nanofibers (1 > x > 0) were synthesized with a scalable, two-step method (electrospinning and subsequent heat treatment). The morphological, structural and electrochemical properties of the LiFexMn1-xPO4/C composite nanofibers were determined by scanning electron microscope, X-ray diffraction and galvanostatic charge/discharge tests. Cathodes made of LiFexMn1-xPO4/C composite nanofibers showed various advantages such as long cycle life, improved electrochemical performance etc. due to the presence of carbon and LiFexMn1-xPO4 in the composite structure. With the addition of Mn to the structure of LiFePO4/C composite nanofibers, electrochemical performance was improved. LiFe0.8Mn0.2PO4/C composite nanofibers showed the best performance in terms of energy density among the samples. Further increment in Mn/Fe ratio resulted declining electrochemical capacity and energy density.
International journal of environment and geoinformatics, Sep 5, 2021
In this study, activated carbon was produced from platanus orientalis leaves and the adsorption o... more In this study, activated carbon was produced from platanus orientalis leaves and the adsorption of methylene blue onto activated carbon was investigated. Facile chemical activation route was conducted for activation process of lignocellulosic leaves. ZnCl 2 was used as an activating agent at different ratios. Morphological, structural properties and adsorption characteristics of samples were determined by using field emission scanning microscopy, Fourier transform infrared spectroscopy, Braunauer-Emmet-Teller spectroscopy and UV-vis spectroscopy. Surface characterization showed that activation with ZnCl 2 resulted high surface area (~1024 m 2 g-1) and total pore volume (~0.431 cm 3 g-1) compared with crude carbonized leaves samples.
In this study, carbon fibers filled flexible conductive polymer composites were fabricated. Turki... more In this study, carbon fibers filled flexible conductive polymer composites were fabricated. Turkish hemp was used to produce conductive carbon fibers. In order to do this, hemp fibers were carbonized under different conditions. After this step, flexible conductive composites were fabricated by using poly[styrene-b-(ethylene-co-butylene)-b-styrene] matrix and hemp-based carbon fibers. Composite films were produced by combination of solvent casting and hot pressing. Various levels of carbon fibers were used in order to determine the percolation behavior of the composites. Morphological and electrical properties of the composite films were analyzed. Electrical resistivity of the samples decreased by increasing the filler ratio.
Thermoplastic elastomer-based fibers have many advantages including lightness, flexibility, resil... more Thermoplastic elastomer-based fibers have many advantages including lightness, flexibility, resilience. Styrene-[ethylene-(ethylene-propylene)]styrene (SEEPS) is a styrenic block copolymer based thermoplastic elastomer and it can be used for many applications with many functions as a matrix, compatibilizer, modifier or adhesive. It has good resistance to oxidizing agents, weathering, aging, and it can be used under various conditions. In this study, SEEPS block copolymer fibers were electrospun. This study is the first study about the electrospinning of SEEPS block copolymer in the literature. Various spinning solutions were used, and process was optimized by changing the electrospinning conditions. Fiber morphology was analyzed by an optical microscope and fiber diameter distribution histograms were drawn. In order to understand the effects of polymer concentration on electrospinning, viscosity of the spinning solutions was measured. Although electrospinning conditions were found to be critical in terms of spinnability, solution concentration and viscosity were the most significant factors for obtaining flexible SEEPS based fibrous nonwoven mats.
With the rapid development of flexible electronics, conductive textiles are becoming important bu... more With the rapid development of flexible electronics, conductive textiles are becoming important building blocks for wearables in broad applications. Different from conventional textiles, conductive textiles require fabrics to have a basic wearable function as well as electrical conductivity. Conductive textiles have been used in applications such as antistatic, electromagnetic (EM) shielding, and e-textiles. In this chapter, we introduce the fundamental principles of conductive textiles and review recent developments of advanced conductive coating technologies and their applications in antistatic, EM shielding, and e-textiles.
Uploads
Papers by ozan toprakci