seyed abdolkarim hosseini - Academia.edu (original) (raw)

Papers by seyed abdolkarim hosseini

Fibers and Polymers

The current research presents the optimization of the parameters involved in the production of po... more The current research presents the optimization of the parameters involved in the production of polyacrylonitrile (PAN) nanofibers via the needleless electrospinning system. The experiments were designed using the Taguchi method to investigate the morphological, physical, and mechanical properties of the nanofibers. The single-wall carbon nanotubes (CNT) were used in order to improve the mechanical properties of the electrospun nanofibers. The diameter of the PAN nanofibers in the needleless system was less than 300 nm, which was smaller than that in the conventional system. The results showed that the concentration had the greatest impact on the fiber diameter than other parameters in both PAN and PAN/CNT nanofibers. The specific stress of the nanofibers produced by the needleless electrospinning system was lower than that created by the conventional electrospinning system. Addition of The CNT caused to improve the specific stress of the PAN/CNT nanofibers compared with the PAN nanofibers. However, excessive amounts of CNT had a negative effect on the elongation and modulus because of the aggregation of CNT inside the nanofibers. The X-ray diffraction analysis was used to study the crystalline behavior of the PAN nanofibers produced via the needleless electrospinning system. The results showed that the PAN nanofibers had amorphous structure compared with the conventional PAN nanofibers.

Polymer Bulletin

The effect(s) of TiO 2 nanoparticles on the vertical wicking behavior observed in electrospun pol... more The effect(s) of TiO 2 nanoparticles on the vertical wicking behavior observed in electrospun polyacrylonitrile (PAN) nanofiber strings of yarn was investigated in this study. The capillary flow was measured in composite nanofiber strings of yarn by means of the image analysis of the rise of colored liquid soaked up in the strings of yarn; the height of liquid rise was determined as a function of time. The kinetics of capillary rise follows the Lucas-Washburn's equation. The results obtained from the experimental design showed that the rate coefficient of the capillary rise was influenced by TiO 2 nanoparticles more than the twist level in nanofiber strings of yarn. For various hot-stretching ratios, the rate of capillary rise decreased with increasing the number of TiO 2 nanoparticles and the level of yarn twist. This decreasing trend was more pronounced at higher levels of yarn twist. To find how capillary behavior changed with the release of nanoparticles, the wicking mechanisms were measured at different concentrations of TiO 2 nanoparticles in capillary liquid. When TiO 2 nanoparticles were used in capillary liquid, they immediately filled the spaces between nanofibers in yarn and the liquid could not rise any more. The present study indicated that the wicking behavior of composite nanofiber strings of yarn was tunable provided that appropriate constructive factors, that is to say, the number of TiO 2 nanoparticles and the level of nanofiber yarn twist, were chosen.

Polymers for Advanced Technologies

Materials Research Express

Poly-L lactic acid (PLLA) is one of the mostly used fibers in biomedical applications as a biodeg... more Poly-L lactic acid (PLLA) is one of the mostly used fibers in biomedical applications as a biodegradable and biocompatible material. Porosity and fiber diameter distribution are governing factors that determine the performance of nanofibers. Present work aims at investigating the process parameters that are affecting porosity and diameter distribution of PLLA nanofibers. PLLA nanofibers were fabricated through electrospinning method using the solution of PLLA polymer/dichloromethane (DCM). Nanofibers with various fiber diameter distribution and porosity were made by changing of process parameters such as spinning distance (5, 10 and 15 cm), voltage (11 and 15 kV), solution concentration (10, 11 and 12 wt%) and feeding rate (0.3, 0.4 and 0.7 ml h−1). Image processing techniques (with Matlab R2017), surface analysis (with Mountainsmap7) and diameter distribution analysis (with Measurement software) were used to examine surface morphology of samples. The results showed that the fiber diameter distribution becomes wider with increasing the applied voltage and reducing the spinning distance. In the other hand, coarse fibers possessed larger pores while having irregular and fewer pores in comparison to fine fibers. The most uniform nano-web with high porous nanofibers was attained by the choice of the process parameters at the voltage of 11 kV, spinning distance of 15 cm, feeding rate of 0.4 ml h−1 and solution concentration of 10 wt%.

e-Polymers

Casein, a natural protein, has been used as a biopolymer-based resource for producing fiber. This... more Casein, a natural protein, has been used as a biopolymer-based resource for producing fiber. This fiber provides high comfort properties with a pH close to human skin. This study focused on evaluating the production feasibility of casein nanofiber twisted yarn with the highest protein content in the hybrid yarn, obtaining suitable spinning conditions and desirable properties of the produced yarn. The desirable yarn achieved by composing 90% casein and 10% polyethylene oxide. The yarn strengthened using several types of cross-linking methods and the best technique was obtained to spin an optimized engineered yarn. Consequently, the biodegrading test conducted on the optimized yarn (90% casein and 10% polyethylene oxide blend) in the presence of 40% di-isocyanate as strengthener additive. Observations showed that after ten days, the sample mostly degraded in the solvent and its strength massively reduced so it could be considered as an environmentally friendly, biodegradable fiber.

Applied Thermal Engineering

Abstract Phase change fibrous layers, produced by coaxial electrospinning, are great candidates t... more Abstract Phase change fibrous layers, produced by coaxial electrospinning, are great candidates to be used in the thermal energy storage systems. In the present work, thermoregulating properties of core-shell fibrous layers containing phase change materials were studied under simulated body conditions. Two types of alkane containing hexadecane and octadecane, as the PCM core, were compared. Morphological observations were carried out by the longitudinal and cross-sectional FESEM images. Thermal performance of samples was investigated using DSC analysis and dynamic heat evaluation system in accordance with the body conditions. The results showed that types of PCM and number of layers had significantly effect on the thermoregulating properties. In addition, three indices, including the mean and maximum temperature difference, the mean gradient temperature (GT), and the cooling rate, were derived from the dynamic test results. The mean temperature difference showed no significant differences between the samples containing PCMs, while the GT and the cooling rate showed longer thermal response times in the samples containing hexadecane in comparison with the other samples. As a result, the PCM with a phase change temperature which is close to ambient temperature is more appropriate choice to achieve a high thermal performance during sudden changes at the ambient temperature.

Journal of Materials Science

This study aimed to investigate the fabrication facility of thermoregulating coreshell fibers fro... more This study aimed to investigate the fabrication facility of thermoregulating coreshell fibers from various polymer solutions as the shell part which surrounded a phase change material (PCM) representing the core part. Fabrication process was drawn through coaxial electrospinning. Polyvinylpyrrolidone (PVP), polyvinylidene fluoride (PVDF) and polyacrylonitrile (PAN) were selected as the promising candidates for shell materials. n-Octadecane was loaded as the lowtemperature PCM in the whole core part. The results showed that PVP had a better ability to form the core-shell structure than the other two polymers. The effect of PVP concentration solution, voltage and the flow rates of the core and shell fluid on the morphology of n-octadecane/polyvinylpyrrolidone (PCM-PVP) fibers was investigated. It was shown that there were the optimum concentration, voltage and feed rate, such that the core-shell structure could be formed without any obstacle. In addition, thermoregulation properties of the fabricated layer were examined with DSC analysis and the simulated body condition setup. DSC results illustrated the phase change enthalpy of about 80 J g-1 , which was related to the PCM-PVP with the PVP concentration of 14% and the shell/core flow rate of 2.0/0.25 ml h-1. There was an encapsulation ratio of about 36%. Simulated body condition also showed the temperature difference of 10°C between the PVP and the PCM-PVP layer at the phase change temperature, which provided valuable results for considering this layer for intelligent textiles.

Journal of Engineered Fibers and Fabrics

The fascinating intramolecular arene/allene cycloaddition discovered by Himbert affords dearomati... more The fascinating intramolecular arene/allene cycloaddition discovered by Himbert affords dearomatized, polycyclic intermediates with sufficient strain energy to drive rearrangement processes of the newly formed ring system. We disclose a detailed examination of a thermally induced stepwise dyotropic skeletal rearrangement of these cycloadducts, a reaction also first described by Himbert. We offer computational evidence for a two-stage mechanism for this formal dyotropic rearrangement and provide rationalizations for the significant substitution-dependent rate differences observed in experiments. These investigations led to the development of a Lewis-acid-catalyzed rearrangement of precursors that were unreactive under simple thermal instigation. The isolation of the product of an "interrupted" rearrangement under Lewis acidic conditions provides further support for the proposed stepwise mechanism. Computational results also matched experiments in terms of regiochemical pref...

Journal of Water and Health

Functionalized nanofibrous membranes have been produced via electrospinning with a polymer soluti... more Functionalized nanofibrous membranes have been produced via electrospinning with a polymer solution of 19% (w/w) of nylon 66 prepared in a formic acid/chloroform mixture (75:25 v/v). The optimum parameters of electrospinning, like voltage, flow rate, tip and collector distances, were achieved and produced nanofiber membranes with a thickness of 287 nm. Then the nanofiber membranes were functionalized by (3-mercaptopropyl)trimethoxysilane (TMPTMS) at various amounts. Three different initial concentrations of metal ions and three different levels of pH were chosen. The effect of filtration process parameters such as the initial concentration of metal solution, pH of the solution, and the amount of functionalizer trimethoxysilane (TMPTMS) on the adsorption was studied. In surveying filtration process parameters, the results showed that metal ion rejection increased by increasing the pH of the solution and decreased by increasing the initial concentration of the effluent. By increasing ...

Journal of Applied Polymer Science, 2016

Textile Research Journal, 1995

Protruding yarns influence a fabric's properties and its end use. This paper discusses a new ... more Protruding yarns influence a fabric's properties and its end use. This paper discusses a new approach to measuring fabric appearance objectively using image processing techniques by Fourier transform analysis. Characteristics of the fabric surface such as directionality, density of yarns protruding from the fabric body, and periodicity of weft and warp yams (yarn spacing) for plain-weave cotton fabric are discussed. The protruding yarn density obtained in this study correlates with those from previous work by spectral analysis of dynamic friction in the fabric surface. This new approach is regarded as a useful method for estimating protruding yam density on fabric surfaces. Through the angular Fourier power spectrum, changes in protruding yarns due to wear are evaluated for yarns spun by different systems such as air-jet, core-spun, open- end, carded, and combed.

Materials Sciences and Applications, 2015

Nowadays, while human requirements are extending, producing nanofibers and nanofiber based produc... more Nowadays, while human requirements are extending, producing nanofibers and nanofiber based products are progressing rapidly. Nanofibers have received considerable study in recent years using various polymers and methods. PAN (Polyacrylonitryle) nanofibers have shown a great potential in producing nanofibers and nanofibre yarn as precursor polymers for making high performance carbon fiber. There is a lack of information about yarn and woven fabrics made out of nanofibers. Current research is aiming to manufacture yarn using well-known electrospinning technique and converting it to woven fabric. A continuous yarn was produced by changing production parameters and using simultaneous twisting and collecting. Values of twist and rate of fiber collecting made it possible to prepare yarn from nanofibres. Consequently, the yarns were used for producing plain weave fabric manually. Some characteristics of the yarn, such as diameter and its distribution along the yarn, specific density, thin and thick places were assessed using image processing technique. Also, characteristics of fabric appearances were investigated.

Journal of Industrial Textiles, 2014

The Taguchi method was adopted to optimize the fabrication condition of solid state polymerized p... more The Taguchi method was adopted to optimize the fabrication condition of solid state polymerized polyamide (SSP PA66) nanofibers with respect to minimizing nanofiber diameter. A novel fabrication system called air-sealed centrifuge electrospinning was used for preparing high-quality nanofibers. In this study, solution concentration, rotational speed, syringe content, and applied voltage were selected as key parameters affecting the diameter of the fabricated nanofibers. The morphology of the electrospun nanofibers was analyzed by using the field-emission scanning electron microscope. Nanofiber diameters ranging from 20 to 250 nm were successfully controlled by the Taguchi method, and the statistical data based on experimental results indicated that the syringe content and rotational speed had greater influences (35.76% and 23.93%, respectively) on nanofiber diameter than did solution concentration and voltage (21.36% and 11.49%, respectively). Lower syringe content as well as higher ...

Journal of Industrial Textiles, 2014

ABSTRACT Specific surface and surface porosity are governing factors in the penetration rate and ... more ABSTRACT Specific surface and surface porosity are governing factors in the penetration rate and the amount of liquid rise into the yarn. In this work, porous and non-porous fiber yarns of poly (l-lactic acid) (PLLA) were fabricated via electrospinning and twist insertion. The surface of PLLA electrospun fibers became porous after evaporation of highly volatile solvent in controlled humidity and temperature and changing the concentration of PLLA solution, resulted in the fibers with different surface porosity. Smooth PLLA nanofibers were obtained using non-volatile solvent. Consequently, capillary rise was investigated in both the porous fiber yarns and smooth nanofiber yarn. Experimental evidences revealed that two morphological characteristics of fibers, i.e. surface porosity and fineness of fibers in the electrospun yarn have a governing effect on the capillary rise phenomenon. Liquid penetration in electrospun yarn was increased by increasing the fiber fineness and/or decreasing the surface porosity. The results of this work suggest that finer fiber and smooth surface would be more beneficial for wicking.

International Journal of Multiphase Flow, 2015

This work presents a comparison between an isolated and a non-isolated curved liquid jet emerging... more This work presents a comparison between an isolated and a non-isolated curved liquid jet emerging from a rotating nozzle through centrifuge spinning system. In the centrifugal spinning process, a polymer solution has been pushed by the centrifugal force through small nozzle of a rapidly rotating cylindrical drum. Thereby thin fibers are formed and collected on a collector in the form of a web. Centrifuge spinning suffered from a strong air resistance which leads to a more deflected jet as well as its rapidly solvent evaporation resulting in thicker nanofibers. In this work, centrifuge spinning has been equipped by a rotating collector, whereas the fabrication process was skillfully sealed from ambient airflow. A comparison was drawn between the trajectory of Newtonian liquid jets fabricated by centrifuge spinning and air-sealed centrifuge spinning. The captured images of the liquid jet trajectory using a high speed camera showed that non-isolated liquid jets were more curved than isolated liquid jets due to air resistance. A pre-presented non-linear analysis of the Navier-Stokes equations was carried out and the numerical solutions were compared with the experiments.There was fairly good agreement between the isolated jet trajectory and the model-predicted one, but there were differences between the non-isolated jet trajectory and the simulation results. The non-isolated jet curved more compared to the others due to air drag. Also, the diameter of polymeric nanofibers was predicted and compared with experiments. Some qualitative agreement was found.

Nowadays, while human requirements are extending, producing nanofibers and nanofiber based produc... more Nowadays, while human requirements are extending, producing nanofibers and nanofiber based products are progressing rapidly. Nanofibers have received considerable study in recent years using various polymers and methods. PAN (Polyacrylonitryle) nanofibers have shown a great potential in producing nanofibers and nanofibre yarn as precursor polymers for making high performance carbon fiber. There is a lack of information about yarn and woven fabrics made out of nanofibers. Current research is aiming to manufacture yarn using well-known electrospinning technique and converting it to woven fabric. A continuous yarn was produced by changing production parameters and using simultaneous twisting and collecting. Values of twist and rate of fiber collecting made it possible to prepare yarn from nanofibres. Consequently, the yarns were used for producing plain weave fabric manually. Some characteristics of the yarn, such as diameter and its distribution along the yarn, specific density, thin and thick places were assessed using image processing technique. Also, characteristics of fabric appearances were investigated.

This work presents a comparison between an isolated and a non-isolated curved liquid jet emerging... more This work presents a comparison between an isolated and a non-isolated curved liquid jet emerging from a rotating nozzle through centrifuge spinning system. In the centrifugal spinning process, a polymer solution has been pushed by the centrifugal force through small nozzle of a rapidly rotating cylindrical drum. Thereby thin fibers are formed and collected on a collector in the form of a web. Centrifuge spinning suffered from a strong air resistance which leads to a more deflected jet as well as its rapidly solvent evaporation resulting in thicker nanofibers. In this work, centrifuge spinning has been equipped by a rotating collector, whereas the fabrication process was skillfully sealed from ambient airflow. A comparison was drawn between the trajectory of Newtonian liquid jets fabricated by centrifuge spinning and air-sealed centrifuge spinning. The captured images of the liquid jet trajectory using a high speed camera showed that non-isolated liquid jets were more curved than isolated liquid jets due to air resistance. A pre-presented non-linear analysis of the Navier-Stokes equations was carried out and the numerical solutions were compared with the experiments.There was fairly good agreement between the isolated jet trajectory and the model-predicted one, but there were differences between the non-isolated jet trajectory and the simulation results. The non-isolated jet curved more compared to the others due to air drag. Also, the diameter of polymeric nanofibers was predicted and compared with experiments. Some qualitative agreement was found.

Fibers and Polymers, 2014

ABSTRACT

Nanoscience &Nanotechnology-Asia, 2015

ABSTRACT

Fibers and Polymers

The current research presents the optimization of the parameters involved in the production of po... more The current research presents the optimization of the parameters involved in the production of polyacrylonitrile (PAN) nanofibers via the needleless electrospinning system. The experiments were designed using the Taguchi method to investigate the morphological, physical, and mechanical properties of the nanofibers. The single-wall carbon nanotubes (CNT) were used in order to improve the mechanical properties of the electrospun nanofibers. The diameter of the PAN nanofibers in the needleless system was less than 300 nm, which was smaller than that in the conventional system. The results showed that the concentration had the greatest impact on the fiber diameter than other parameters in both PAN and PAN/CNT nanofibers. The specific stress of the nanofibers produced by the needleless electrospinning system was lower than that created by the conventional electrospinning system. Addition of The CNT caused to improve the specific stress of the PAN/CNT nanofibers compared with the PAN nanofibers. However, excessive amounts of CNT had a negative effect on the elongation and modulus because of the aggregation of CNT inside the nanofibers. The X-ray diffraction analysis was used to study the crystalline behavior of the PAN nanofibers produced via the needleless electrospinning system. The results showed that the PAN nanofibers had amorphous structure compared with the conventional PAN nanofibers.

Polymer Bulletin

The effect(s) of TiO 2 nanoparticles on the vertical wicking behavior observed in electrospun pol... more The effect(s) of TiO 2 nanoparticles on the vertical wicking behavior observed in electrospun polyacrylonitrile (PAN) nanofiber strings of yarn was investigated in this study. The capillary flow was measured in composite nanofiber strings of yarn by means of the image analysis of the rise of colored liquid soaked up in the strings of yarn; the height of liquid rise was determined as a function of time. The kinetics of capillary rise follows the Lucas-Washburn's equation. The results obtained from the experimental design showed that the rate coefficient of the capillary rise was influenced by TiO 2 nanoparticles more than the twist level in nanofiber strings of yarn. For various hot-stretching ratios, the rate of capillary rise decreased with increasing the number of TiO 2 nanoparticles and the level of yarn twist. This decreasing trend was more pronounced at higher levels of yarn twist. To find how capillary behavior changed with the release of nanoparticles, the wicking mechanisms were measured at different concentrations of TiO 2 nanoparticles in capillary liquid. When TiO 2 nanoparticles were used in capillary liquid, they immediately filled the spaces between nanofibers in yarn and the liquid could not rise any more. The present study indicated that the wicking behavior of composite nanofiber strings of yarn was tunable provided that appropriate constructive factors, that is to say, the number of TiO 2 nanoparticles and the level of nanofiber yarn twist, were chosen.

Polymers for Advanced Technologies

Materials Research Express

Poly-L lactic acid (PLLA) is one of the mostly used fibers in biomedical applications as a biodeg... more Poly-L lactic acid (PLLA) is one of the mostly used fibers in biomedical applications as a biodegradable and biocompatible material. Porosity and fiber diameter distribution are governing factors that determine the performance of nanofibers. Present work aims at investigating the process parameters that are affecting porosity and diameter distribution of PLLA nanofibers. PLLA nanofibers were fabricated through electrospinning method using the solution of PLLA polymer/dichloromethane (DCM). Nanofibers with various fiber diameter distribution and porosity were made by changing of process parameters such as spinning distance (5, 10 and 15 cm), voltage (11 and 15 kV), solution concentration (10, 11 and 12 wt%) and feeding rate (0.3, 0.4 and 0.7 ml h−1). Image processing techniques (with Matlab R2017), surface analysis (with Mountainsmap7) and diameter distribution analysis (with Measurement software) were used to examine surface morphology of samples. The results showed that the fiber diameter distribution becomes wider with increasing the applied voltage and reducing the spinning distance. In the other hand, coarse fibers possessed larger pores while having irregular and fewer pores in comparison to fine fibers. The most uniform nano-web with high porous nanofibers was attained by the choice of the process parameters at the voltage of 11 kV, spinning distance of 15 cm, feeding rate of 0.4 ml h−1 and solution concentration of 10 wt%.

e-Polymers

Casein, a natural protein, has been used as a biopolymer-based resource for producing fiber. This... more Casein, a natural protein, has been used as a biopolymer-based resource for producing fiber. This fiber provides high comfort properties with a pH close to human skin. This study focused on evaluating the production feasibility of casein nanofiber twisted yarn with the highest protein content in the hybrid yarn, obtaining suitable spinning conditions and desirable properties of the produced yarn. The desirable yarn achieved by composing 90% casein and 10% polyethylene oxide. The yarn strengthened using several types of cross-linking methods and the best technique was obtained to spin an optimized engineered yarn. Consequently, the biodegrading test conducted on the optimized yarn (90% casein and 10% polyethylene oxide blend) in the presence of 40% di-isocyanate as strengthener additive. Observations showed that after ten days, the sample mostly degraded in the solvent and its strength massively reduced so it could be considered as an environmentally friendly, biodegradable fiber.

Applied Thermal Engineering

Abstract Phase change fibrous layers, produced by coaxial electrospinning, are great candidates t... more Abstract Phase change fibrous layers, produced by coaxial electrospinning, are great candidates to be used in the thermal energy storage systems. In the present work, thermoregulating properties of core-shell fibrous layers containing phase change materials were studied under simulated body conditions. Two types of alkane containing hexadecane and octadecane, as the PCM core, were compared. Morphological observations were carried out by the longitudinal and cross-sectional FESEM images. Thermal performance of samples was investigated using DSC analysis and dynamic heat evaluation system in accordance with the body conditions. The results showed that types of PCM and number of layers had significantly effect on the thermoregulating properties. In addition, three indices, including the mean and maximum temperature difference, the mean gradient temperature (GT), and the cooling rate, were derived from the dynamic test results. The mean temperature difference showed no significant differences between the samples containing PCMs, while the GT and the cooling rate showed longer thermal response times in the samples containing hexadecane in comparison with the other samples. As a result, the PCM with a phase change temperature which is close to ambient temperature is more appropriate choice to achieve a high thermal performance during sudden changes at the ambient temperature.

Journal of Materials Science

This study aimed to investigate the fabrication facility of thermoregulating coreshell fibers fro... more This study aimed to investigate the fabrication facility of thermoregulating coreshell fibers from various polymer solutions as the shell part which surrounded a phase change material (PCM) representing the core part. Fabrication process was drawn through coaxial electrospinning. Polyvinylpyrrolidone (PVP), polyvinylidene fluoride (PVDF) and polyacrylonitrile (PAN) were selected as the promising candidates for shell materials. n-Octadecane was loaded as the lowtemperature PCM in the whole core part. The results showed that PVP had a better ability to form the core-shell structure than the other two polymers. The effect of PVP concentration solution, voltage and the flow rates of the core and shell fluid on the morphology of n-octadecane/polyvinylpyrrolidone (PCM-PVP) fibers was investigated. It was shown that there were the optimum concentration, voltage and feed rate, such that the core-shell structure could be formed without any obstacle. In addition, thermoregulation properties of the fabricated layer were examined with DSC analysis and the simulated body condition setup. DSC results illustrated the phase change enthalpy of about 80 J g-1 , which was related to the PCM-PVP with the PVP concentration of 14% and the shell/core flow rate of 2.0/0.25 ml h-1. There was an encapsulation ratio of about 36%. Simulated body condition also showed the temperature difference of 10°C between the PVP and the PCM-PVP layer at the phase change temperature, which provided valuable results for considering this layer for intelligent textiles.

Journal of Engineered Fibers and Fabrics

The fascinating intramolecular arene/allene cycloaddition discovered by Himbert affords dearomati... more The fascinating intramolecular arene/allene cycloaddition discovered by Himbert affords dearomatized, polycyclic intermediates with sufficient strain energy to drive rearrangement processes of the newly formed ring system. We disclose a detailed examination of a thermally induced stepwise dyotropic skeletal rearrangement of these cycloadducts, a reaction also first described by Himbert. We offer computational evidence for a two-stage mechanism for this formal dyotropic rearrangement and provide rationalizations for the significant substitution-dependent rate differences observed in experiments. These investigations led to the development of a Lewis-acid-catalyzed rearrangement of precursors that were unreactive under simple thermal instigation. The isolation of the product of an "interrupted" rearrangement under Lewis acidic conditions provides further support for the proposed stepwise mechanism. Computational results also matched experiments in terms of regiochemical pref...

Journal of Water and Health

Functionalized nanofibrous membranes have been produced via electrospinning with a polymer soluti... more Functionalized nanofibrous membranes have been produced via electrospinning with a polymer solution of 19% (w/w) of nylon 66 prepared in a formic acid/chloroform mixture (75:25 v/v). The optimum parameters of electrospinning, like voltage, flow rate, tip and collector distances, were achieved and produced nanofiber membranes with a thickness of 287 nm. Then the nanofiber membranes were functionalized by (3-mercaptopropyl)trimethoxysilane (TMPTMS) at various amounts. Three different initial concentrations of metal ions and three different levels of pH were chosen. The effect of filtration process parameters such as the initial concentration of metal solution, pH of the solution, and the amount of functionalizer trimethoxysilane (TMPTMS) on the adsorption was studied. In surveying filtration process parameters, the results showed that metal ion rejection increased by increasing the pH of the solution and decreased by increasing the initial concentration of the effluent. By increasing ...

Journal of Applied Polymer Science, 2016

Textile Research Journal, 1995

Protruding yarns influence a fabric's properties and its end use. This paper discusses a new ... more Protruding yarns influence a fabric's properties and its end use. This paper discusses a new approach to measuring fabric appearance objectively using image processing techniques by Fourier transform analysis. Characteristics of the fabric surface such as directionality, density of yarns protruding from the fabric body, and periodicity of weft and warp yams (yarn spacing) for plain-weave cotton fabric are discussed. The protruding yarn density obtained in this study correlates with those from previous work by spectral analysis of dynamic friction in the fabric surface. This new approach is regarded as a useful method for estimating protruding yam density on fabric surfaces. Through the angular Fourier power spectrum, changes in protruding yarns due to wear are evaluated for yarns spun by different systems such as air-jet, core-spun, open- end, carded, and combed.

Materials Sciences and Applications, 2015

Nowadays, while human requirements are extending, producing nanofibers and nanofiber based produc... more Nowadays, while human requirements are extending, producing nanofibers and nanofiber based products are progressing rapidly. Nanofibers have received considerable study in recent years using various polymers and methods. PAN (Polyacrylonitryle) nanofibers have shown a great potential in producing nanofibers and nanofibre yarn as precursor polymers for making high performance carbon fiber. There is a lack of information about yarn and woven fabrics made out of nanofibers. Current research is aiming to manufacture yarn using well-known electrospinning technique and converting it to woven fabric. A continuous yarn was produced by changing production parameters and using simultaneous twisting and collecting. Values of twist and rate of fiber collecting made it possible to prepare yarn from nanofibres. Consequently, the yarns were used for producing plain weave fabric manually. Some characteristics of the yarn, such as diameter and its distribution along the yarn, specific density, thin and thick places were assessed using image processing technique. Also, characteristics of fabric appearances were investigated.

Journal of Industrial Textiles, 2014

The Taguchi method was adopted to optimize the fabrication condition of solid state polymerized p... more The Taguchi method was adopted to optimize the fabrication condition of solid state polymerized polyamide (SSP PA66) nanofibers with respect to minimizing nanofiber diameter. A novel fabrication system called air-sealed centrifuge electrospinning was used for preparing high-quality nanofibers. In this study, solution concentration, rotational speed, syringe content, and applied voltage were selected as key parameters affecting the diameter of the fabricated nanofibers. The morphology of the electrospun nanofibers was analyzed by using the field-emission scanning electron microscope. Nanofiber diameters ranging from 20 to 250 nm were successfully controlled by the Taguchi method, and the statistical data based on experimental results indicated that the syringe content and rotational speed had greater influences (35.76% and 23.93%, respectively) on nanofiber diameter than did solution concentration and voltage (21.36% and 11.49%, respectively). Lower syringe content as well as higher ...

Journal of Industrial Textiles, 2014

ABSTRACT Specific surface and surface porosity are governing factors in the penetration rate and ... more ABSTRACT Specific surface and surface porosity are governing factors in the penetration rate and the amount of liquid rise into the yarn. In this work, porous and non-porous fiber yarns of poly (l-lactic acid) (PLLA) were fabricated via electrospinning and twist insertion. The surface of PLLA electrospun fibers became porous after evaporation of highly volatile solvent in controlled humidity and temperature and changing the concentration of PLLA solution, resulted in the fibers with different surface porosity. Smooth PLLA nanofibers were obtained using non-volatile solvent. Consequently, capillary rise was investigated in both the porous fiber yarns and smooth nanofiber yarn. Experimental evidences revealed that two morphological characteristics of fibers, i.e. surface porosity and fineness of fibers in the electrospun yarn have a governing effect on the capillary rise phenomenon. Liquid penetration in electrospun yarn was increased by increasing the fiber fineness and/or decreasing the surface porosity. The results of this work suggest that finer fiber and smooth surface would be more beneficial for wicking.

International Journal of Multiphase Flow, 2015

This work presents a comparison between an isolated and a non-isolated curved liquid jet emerging... more This work presents a comparison between an isolated and a non-isolated curved liquid jet emerging from a rotating nozzle through centrifuge spinning system. In the centrifugal spinning process, a polymer solution has been pushed by the centrifugal force through small nozzle of a rapidly rotating cylindrical drum. Thereby thin fibers are formed and collected on a collector in the form of a web. Centrifuge spinning suffered from a strong air resistance which leads to a more deflected jet as well as its rapidly solvent evaporation resulting in thicker nanofibers. In this work, centrifuge spinning has been equipped by a rotating collector, whereas the fabrication process was skillfully sealed from ambient airflow. A comparison was drawn between the trajectory of Newtonian liquid jets fabricated by centrifuge spinning and air-sealed centrifuge spinning. The captured images of the liquid jet trajectory using a high speed camera showed that non-isolated liquid jets were more curved than isolated liquid jets due to air resistance. A pre-presented non-linear analysis of the Navier-Stokes equations was carried out and the numerical solutions were compared with the experiments.There was fairly good agreement between the isolated jet trajectory and the model-predicted one, but there were differences between the non-isolated jet trajectory and the simulation results. The non-isolated jet curved more compared to the others due to air drag. Also, the diameter of polymeric nanofibers was predicted and compared with experiments. Some qualitative agreement was found.

Nowadays, while human requirements are extending, producing nanofibers and nanofiber based produc... more Nowadays, while human requirements are extending, producing nanofibers and nanofiber based products are progressing rapidly. Nanofibers have received considerable study in recent years using various polymers and methods. PAN (Polyacrylonitryle) nanofibers have shown a great potential in producing nanofibers and nanofibre yarn as precursor polymers for making high performance carbon fiber. There is a lack of information about yarn and woven fabrics made out of nanofibers. Current research is aiming to manufacture yarn using well-known electrospinning technique and converting it to woven fabric. A continuous yarn was produced by changing production parameters and using simultaneous twisting and collecting. Values of twist and rate of fiber collecting made it possible to prepare yarn from nanofibres. Consequently, the yarns were used for producing plain weave fabric manually. Some characteristics of the yarn, such as diameter and its distribution along the yarn, specific density, thin and thick places were assessed using image processing technique. Also, characteristics of fabric appearances were investigated.

This work presents a comparison between an isolated and a non-isolated curved liquid jet emerging... more This work presents a comparison between an isolated and a non-isolated curved liquid jet emerging from a rotating nozzle through centrifuge spinning system. In the centrifugal spinning process, a polymer solution has been pushed by the centrifugal force through small nozzle of a rapidly rotating cylindrical drum. Thereby thin fibers are formed and collected on a collector in the form of a web. Centrifuge spinning suffered from a strong air resistance which leads to a more deflected jet as well as its rapidly solvent evaporation resulting in thicker nanofibers. In this work, centrifuge spinning has been equipped by a rotating collector, whereas the fabrication process was skillfully sealed from ambient airflow. A comparison was drawn between the trajectory of Newtonian liquid jets fabricated by centrifuge spinning and air-sealed centrifuge spinning. The captured images of the liquid jet trajectory using a high speed camera showed that non-isolated liquid jets were more curved than isolated liquid jets due to air resistance. A pre-presented non-linear analysis of the Navier-Stokes equations was carried out and the numerical solutions were compared with the experiments.There was fairly good agreement between the isolated jet trajectory and the model-predicted one, but there were differences between the non-isolated jet trajectory and the simulation results. The non-isolated jet curved more compared to the others due to air drag. Also, the diameter of polymeric nanofibers was predicted and compared with experiments. Some qualitative agreement was found.

Fibers and Polymers, 2014

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Nanoscience &Nanotechnology-Asia, 2015

ABSTRACT