A novel and facile one-step approach to in situ synthesize silver nanoparticle-filled nylon 6 nan... more A novel and facile one-step approach to in situ synthesize silver nanoparticle-filled nylon 6 nanofibers by electrospinning is reported. The method does not need post-treatments and can be carried out at ambient conditions without using additional chemicals. It employs the electrospinning solvent as a reducing agent for in situ conversion of AgNO 3 into silver nanoparticles during the solution preparation. The resultant silver nanoparticle-filled nylon 6 hybrid nanofibers show an excellent fibrous structure (fiber diameter at 50-150 nm), with narrow size 2-4 nm silver nanoparticles uniformly dispersed throughout the nylon 6 matrix. DSC analysis shows that the in situ incorporation of silver nanoparticles increased the T g and crystallinity of the resultant nanofibers. These silver nanoparticlefilled nylon 6 nanofibers exhibit a steady and long-lasting silver ion release behavior, and robust antibacterial activity against both Gram-positive B. cereus and Gram-negative E. coli microorganisms.
ABSTRACT Polypropylene and nylon 66 fabrics are subjected to atmospheric pressure He and He-O2 pl... more ABSTRACT Polypropylene and nylon 66 fabrics are subjected to atmospheric pressure He and He-O2 plasmas for selected exposure time intervals. Scanning electron microscopy anal ysis of the fabrics shows no apparent changes in the plasma-treated nylon fiber surfaces, but significant surface morphological changes for the polypropylene. Surface analyses of the nylon filaments reveal small differences in the surface carbon and oxygen contents between the treated and control groups. The surface oxygen and nitrogen content of the polypropylene fabric increases significantly after treatment in both He and He-O2 plasmas. There is a slight decrease in nylon fabric tensile strength after treatment in He plasma for 3 minutes, while. there is no significant change in tensile strength of the nylon fabric treated with He-O2 after exposure times of up to 8 minutes.
ABSTRACT In this study, both air-oxygen-helium and air-helium atmospheric pressure plasma treatme... more ABSTRACT In this study, both air-oxygen-helium and air-helium atmospheric pressure plasma treatments were employed to desize PVA on a rayon (viscose) fabric. Both the plasma treatments were able to remove some of the PVA on the rayon fabric and increase PVA solubility in cold water, resulting in a higher weight loss in cold washing. The effect of the atmospheric pressure plasmas became greater as the treatment time increased. Plasma treatment followed by one cold and one hot washing had the same effect as the conventional chemical treatments followed by two cycles of cold and hot washing. The atmospheric plasma treatment did not have negative effect on rayon fabric tensile strength.
ABSTRACT Atmospheric plasma desizing of poly(vinyl alcohol) (PVA) films was investigated using PV... more ABSTRACT Atmospheric plasma desizing of poly(vinyl alcohol) (PVA) films was investigated using PVA films supplied by MonoSol. LLCO. The MonoSol (MS) films were exposed to atmospheric plasma for 0.5 to 5.0 min in thirty-second increments with additional specimens exposed for 8.0 and 10.0 min durations. Plasma treatment included exposure to helium plasma (He), oxygenated-helium plasma (He/O-2), and helium/carbon tetrafluoride (He/CF4) plasma. The treated films were characterized by weight loss, surface ablation, molecular weight, and solubility. Weight loss data suggested a mechanism of continual ablation, which increases with increased exposure time until saturation. Redeposition of ablated species may take place because the treatment is in a closed-geometry and thus the saturation trend slightly changes. Thickness changes/surface ablation is in good correlation with the weight loss trends, which suggests that the ablation mechanism is responsible for surface removal. Gel permeation chromatography showed a progressive reduction in the weight-average molecular weight of the PVA chains with increasing treatment durations. This reduction is attributed to chain-scission caused by plasma exposure. Solubility tests showed an increase in solubility of plasma-exposed films in methanol, with a decrease in swelling. These results correlate well with the chain-scission observed through GPC and weight loss trends. On-line atmospheric pressure plasma desizing of textile materials.
Atomic layer deposition (ALD) can be used to coat high aspect ratio and high surface area substra... more Atomic layer deposition (ALD) can be used to coat high aspect ratio and high surface area substrates with conformal and precisely controlled thin films. Vertically aligned arrays of multiwalled carbon nanotubes (MWCNTs) with lengths up to 1.5 mm were conformally coated with alumina from base to tip. The nucleation and growth behaviors of Al2O3 ALD precursors on the MWCNTs were studied as a function of CNT surface chemistry. CNT surfaces were modified through a series of post-treatments including pyrolytic carbon deposition, high temperature thermal annealing, and oxygen plasma functionalization. Conformal coatings were achieved where post-treatments resulted in increased defect density as well as the extent of functionalization, as characterized by X-ray photoelectron spectroscopy and Raman spectroscopy. Using thermogravimetric analysis, it was determined that MWCNTs treated with pyrolytic carbon and plasma functionalization prior to ALD coating were more stable to thermal oxidation than pristine ALD coated samples. Functionalized and ALD coated arrays had a compressive modulus more than two times higher than a pristine array coated for the same number of cycles. Cross-sectional energy dispersive X-ray spectroscopy confirmed that Al2O3 could be uniformly deposited through the entire thickness of the vertically aligned MWCNT array by manipulating sample orientation and mounting techniques. Following the ALD coating, the MWCNT arrays demonstrated hydrophilic wetting behavior and also exhibited foam-like recovery following compressive strain.
... Derivatives SM Gawish and AM Ramadan National Research Center, Textile Division, Cairo, Egypt... more ... Derivatives SM Gawish and AM Ramadan National Research Center, Textile Division, Cairo, Egypt CE Cornelius and MA Bourham1 Department of Nuclear Engineering, North Carolina State University, Raleigh, NC 27695-7909, USA ...
Science and Technology of Advanced Materials, 2011
ZnO/Nylon 6 nanofiber mats were prepared by an electrospinning-electrospraying hybrid process in ... more ZnO/Nylon 6 nanofiber mats were prepared by an electrospinning-electrospraying hybrid process in which ZnO nanoparticles were dispersed on the surface of Nylon 6 nanofibers without becoming completely embedded. The prepared ZnO/Nylon 6 nanofiber mats were evaluated for their abilities to kill bacteria or inhibit their growth and to catalytically detoxify chemicals. Results showed that these ZnO/Nylon 6 nanofiber mats had excellent antibacterial efficiency (99.99%) against both the Gram-negative Escherichia coli and Gram-positive Bacillus cereus bacteria. In addition, they exhibited good detoxifying efficiency (95%) against paraoxon, a simulant of highly toxic chemicals. ZnO/Nylon 6 nanofiber mats were also deposited onto nylon/cotton woven fabrics and the nanofiber mats did not significantly affect the moisture vapor transmission rates and air permeability values of the fabrics. Therefore, ZnO/Nylon 6 nanofiber mats prepared by the electrospinning-electrospraying hybrid process are promising material candidates for protective applications.
Electrospun nanofiber mats are inherently weak, and hence they are often deposited on mechanicall... more Electrospun nanofiber mats are inherently weak, and hence they are often deposited on mechanically-strong substrates such as porous woven fabrics that can provide good structural support without altering the nanofiber characteristics. One major challenge of this approach is to ensure good adhesion of nanofiber mats onto the substrates and to achieve satisfactory durability of nanofiber mats against flexion and abrasion during practical use. In this work, Nylon 6 nanofibers were deposited on plasma-pretreated woven fabric substrates through a new plasma-electrospinning hybrid process with the objective of improving adhesion between nanofibers and fabric substrates. The as-prepared Nylon 6 nanofiber-deposited woven fabrics were evaluated for adhesion strength and durability of nanofiber mats by carrying out peel strength and flex resistance tests. The test results showed significant improvement in the adhesion of nanofiber mats on woven fabric substrates. The nanofiber-deposited woven fabrics also exhibited good resistance to damage under repetitive flexion. X-Ray photoelectron spectroscopy and water contact angle analyses were conducted to study the plasma effect on the nanofibers and substrate fabric, and the results suggested that both the plasma pretreatment and plasma-electrospinning hybrid process introduced radicals, increased oxygen contents, and led to the formation of active chemical sites on the nanofiber and substrate surfaces. These active sites helped in creating crosslinking bonds between substrate fabric and electrospun nanofibers, which in turn increased the adhesion properties. The work demonstrates that the plasma-electrospinning hybrid process of nanofiber mats is a promising method to prepare durable functional materials.
Journal of Polymer Science Part B: Polymer Physics, 2011
... Fiber and Polymer Science Program, Department of Textile Engineering, Chemistry and Science, ... more ... Fiber and Polymer Science Program, Department of Textile Engineering, Chemistry and Science, North Carolina State University, Raleigh, North Carolina 27695-8301. Publication History. ... 18 Demir, MM; Yilgor, I.; Yilgor, E.; Erman, B. Polymer 2002, 43, 3303–3309. ...
Electrospun nylon 6 fiber mats were deposited on woven 50/50 nylon/cotton fabric with the motive ... more Electrospun nylon 6 fiber mats were deposited on woven 50/50 nylon/cotton fabric with the motive of making them into protective material against submicron-level aerosol chemical and biological threats. Polymer solution concentration, electrospinning voltage, and deposition areal densities were varied to establish the relationships of processing-structure-filtration efficiency of electrospun fiber mats. A high barrier efficiency of greater than 99.5% was achieved on electrospun fiber mats without sacrificing air permeability and pressure drop.
The surface of a polyethylene terephthalate (PET) spunbond nonwoven was modified by using atmosph... more The surface of a polyethylene terephthalate (PET) spunbond nonwoven was modified by using atmospheric pressure He/O 2 plasma treatment. Accessibility of the modified PET nonwoven has been investigated in terms of crystallinity, surface chemical composition, hydrophilicity, and dye uptake. Differential scanning calorimetry (DSC) for crystallinity measurement and X-ray photoelectron spectroscopy (XPS) for chemical composition measurement were used. Surface morphology was studied by using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Percentage crystallinity increased due to the deple-tion of amorphous region by plasma etching. Redeposition of etched particles was observed. Oxygen-based functional groups on the surface of PET increase from 27 to about 32% after 90 s exposure. Wettability increases by more than 10 times and moisture regain increases by three times, compared with the untreated sample. Dye uptake was not changed significantly.
... then move to form new crystals or cause small crystals to grow in size; (2) etching creates s... more ... then move to form new crystals or cause small crystals to grow in size; (2) etching creates spacing in the polymer network, allowing for ... when testing the dyeability of PET treated in a vacuum plasma.12 The following sections will further develop the validity of this mechanism. ...
Durable antibacterial Ag/polyacrylonitrile (Ag/PAN) hybrid nanofibers were prepared by atmospheri... more Durable antibacterial Ag/polyacrylonitrile (Ag/PAN) hybrid nanofibers were prepared by atmospheric plasma treatment and electrospinning. Atmospheric helium plasma treatment was first used to reduce the AgNO 3 precursor in pre-electrospinning solutions into metallic silver nanoparticles, followed by electrospinning into continuous and smooth nanofibers with Ag nanoparticles embedded in the matrix. SEM, TEM, and EDX spectra were used to study the structure and surface elemental composition of the nanofibers. Silver nanoparticles, with diameters ranging between 3 and 6 nm, were found to be uniformly dispersed in the nanofiber matrix. The Ag/PAN nanofibers exhibited slow and long-lasting silver ion release, which provided robust antibacterial activity against both Gram-positive Bacillus cereus and Gram-negative Escherichia coli microorganisms.
A multifunctional and durable nanofiber-fabric-layered composite (NFLC) material was prepared by ... more A multifunctional and durable nanofiber-fabric-layered composite (NFLC) material was prepared by depositing electrospun Ag/PAN hybrid nanofibers onto a Nylon/cotton 50: 50 fabric substrate. The NFLCs showed excellent aerosol barrier efficiency and good air/moisture permeability. In addition, they showed excellent antibacterial efficiency by completely inhibiting the growth of both Gram-negative E. coli and Gram-positive S. aureus. The interfacial adhesion between the nanofiber layer and fabric substrate was significantly improved by atmospheric plasma pretreatment of the substrate. The resultant NFLCs showed excellent resistance to peeling, twisting, and flexing forces.
A novel and facile one-step approach to in situ synthesize silver nanoparticle-filled nylon 6 nan... more A novel and facile one-step approach to in situ synthesize silver nanoparticle-filled nylon 6 nanofibers by electrospinning is reported. The method does not need post-treatments and can be carried out at ambient conditions without using additional chemicals. It employs the electrospinning solvent as a reducing agent for in situ conversion of AgNO 3 into silver nanoparticles during the solution preparation. The resultant silver nanoparticle-filled nylon 6 hybrid nanofibers show an excellent fibrous structure (fiber diameter at 50-150 nm), with narrow size 2-4 nm silver nanoparticles uniformly dispersed throughout the nylon 6 matrix. DSC analysis shows that the in situ incorporation of silver nanoparticles increased the T g and crystallinity of the resultant nanofibers. These silver nanoparticlefilled nylon 6 nanofibers exhibit a steady and long-lasting silver ion release behavior, and robust antibacterial activity against both Gram-positive B. cereus and Gram-negative E. coli microorganisms.
ABSTRACT Polypropylene and nylon 66 fabrics are subjected to atmospheric pressure He and He-O2 pl... more ABSTRACT Polypropylene and nylon 66 fabrics are subjected to atmospheric pressure He and He-O2 plasmas for selected exposure time intervals. Scanning electron microscopy anal ysis of the fabrics shows no apparent changes in the plasma-treated nylon fiber surfaces, but significant surface morphological changes for the polypropylene. Surface analyses of the nylon filaments reveal small differences in the surface carbon and oxygen contents between the treated and control groups. The surface oxygen and nitrogen content of the polypropylene fabric increases significantly after treatment in both He and He-O2 plasmas. There is a slight decrease in nylon fabric tensile strength after treatment in He plasma for 3 minutes, while. there is no significant change in tensile strength of the nylon fabric treated with He-O2 after exposure times of up to 8 minutes.
ABSTRACT In this study, both air-oxygen-helium and air-helium atmospheric pressure plasma treatme... more ABSTRACT In this study, both air-oxygen-helium and air-helium atmospheric pressure plasma treatments were employed to desize PVA on a rayon (viscose) fabric. Both the plasma treatments were able to remove some of the PVA on the rayon fabric and increase PVA solubility in cold water, resulting in a higher weight loss in cold washing. The effect of the atmospheric pressure plasmas became greater as the treatment time increased. Plasma treatment followed by one cold and one hot washing had the same effect as the conventional chemical treatments followed by two cycles of cold and hot washing. The atmospheric plasma treatment did not have negative effect on rayon fabric tensile strength.
ABSTRACT Atmospheric plasma desizing of poly(vinyl alcohol) (PVA) films was investigated using PV... more ABSTRACT Atmospheric plasma desizing of poly(vinyl alcohol) (PVA) films was investigated using PVA films supplied by MonoSol. LLCO. The MonoSol (MS) films were exposed to atmospheric plasma for 0.5 to 5.0 min in thirty-second increments with additional specimens exposed for 8.0 and 10.0 min durations. Plasma treatment included exposure to helium plasma (He), oxygenated-helium plasma (He/O-2), and helium/carbon tetrafluoride (He/CF4) plasma. The treated films were characterized by weight loss, surface ablation, molecular weight, and solubility. Weight loss data suggested a mechanism of continual ablation, which increases with increased exposure time until saturation. Redeposition of ablated species may take place because the treatment is in a closed-geometry and thus the saturation trend slightly changes. Thickness changes/surface ablation is in good correlation with the weight loss trends, which suggests that the ablation mechanism is responsible for surface removal. Gel permeation chromatography showed a progressive reduction in the weight-average molecular weight of the PVA chains with increasing treatment durations. This reduction is attributed to chain-scission caused by plasma exposure. Solubility tests showed an increase in solubility of plasma-exposed films in methanol, with a decrease in swelling. These results correlate well with the chain-scission observed through GPC and weight loss trends. On-line atmospheric pressure plasma desizing of textile materials.
Atomic layer deposition (ALD) can be used to coat high aspect ratio and high surface area substra... more Atomic layer deposition (ALD) can be used to coat high aspect ratio and high surface area substrates with conformal and precisely controlled thin films. Vertically aligned arrays of multiwalled carbon nanotubes (MWCNTs) with lengths up to 1.5 mm were conformally coated with alumina from base to tip. The nucleation and growth behaviors of Al2O3 ALD precursors on the MWCNTs were studied as a function of CNT surface chemistry. CNT surfaces were modified through a series of post-treatments including pyrolytic carbon deposition, high temperature thermal annealing, and oxygen plasma functionalization. Conformal coatings were achieved where post-treatments resulted in increased defect density as well as the extent of functionalization, as characterized by X-ray photoelectron spectroscopy and Raman spectroscopy. Using thermogravimetric analysis, it was determined that MWCNTs treated with pyrolytic carbon and plasma functionalization prior to ALD coating were more stable to thermal oxidation than pristine ALD coated samples. Functionalized and ALD coated arrays had a compressive modulus more than two times higher than a pristine array coated for the same number of cycles. Cross-sectional energy dispersive X-ray spectroscopy confirmed that Al2O3 could be uniformly deposited through the entire thickness of the vertically aligned MWCNT array by manipulating sample orientation and mounting techniques. Following the ALD coating, the MWCNT arrays demonstrated hydrophilic wetting behavior and also exhibited foam-like recovery following compressive strain.
... Derivatives SM Gawish and AM Ramadan National Research Center, Textile Division, Cairo, Egypt... more ... Derivatives SM Gawish and AM Ramadan National Research Center, Textile Division, Cairo, Egypt CE Cornelius and MA Bourham1 Department of Nuclear Engineering, North Carolina State University, Raleigh, NC 27695-7909, USA ...
Science and Technology of Advanced Materials, 2011
ZnO/Nylon 6 nanofiber mats were prepared by an electrospinning-electrospraying hybrid process in ... more ZnO/Nylon 6 nanofiber mats were prepared by an electrospinning-electrospraying hybrid process in which ZnO nanoparticles were dispersed on the surface of Nylon 6 nanofibers without becoming completely embedded. The prepared ZnO/Nylon 6 nanofiber mats were evaluated for their abilities to kill bacteria or inhibit their growth and to catalytically detoxify chemicals. Results showed that these ZnO/Nylon 6 nanofiber mats had excellent antibacterial efficiency (99.99%) against both the Gram-negative Escherichia coli and Gram-positive Bacillus cereus bacteria. In addition, they exhibited good detoxifying efficiency (95%) against paraoxon, a simulant of highly toxic chemicals. ZnO/Nylon 6 nanofiber mats were also deposited onto nylon/cotton woven fabrics and the nanofiber mats did not significantly affect the moisture vapor transmission rates and air permeability values of the fabrics. Therefore, ZnO/Nylon 6 nanofiber mats prepared by the electrospinning-electrospraying hybrid process are promising material candidates for protective applications.
Electrospun nanofiber mats are inherently weak, and hence they are often deposited on mechanicall... more Electrospun nanofiber mats are inherently weak, and hence they are often deposited on mechanically-strong substrates such as porous woven fabrics that can provide good structural support without altering the nanofiber characteristics. One major challenge of this approach is to ensure good adhesion of nanofiber mats onto the substrates and to achieve satisfactory durability of nanofiber mats against flexion and abrasion during practical use. In this work, Nylon 6 nanofibers were deposited on plasma-pretreated woven fabric substrates through a new plasma-electrospinning hybrid process with the objective of improving adhesion between nanofibers and fabric substrates. The as-prepared Nylon 6 nanofiber-deposited woven fabrics were evaluated for adhesion strength and durability of nanofiber mats by carrying out peel strength and flex resistance tests. The test results showed significant improvement in the adhesion of nanofiber mats on woven fabric substrates. The nanofiber-deposited woven fabrics also exhibited good resistance to damage under repetitive flexion. X-Ray photoelectron spectroscopy and water contact angle analyses were conducted to study the plasma effect on the nanofibers and substrate fabric, and the results suggested that both the plasma pretreatment and plasma-electrospinning hybrid process introduced radicals, increased oxygen contents, and led to the formation of active chemical sites on the nanofiber and substrate surfaces. These active sites helped in creating crosslinking bonds between substrate fabric and electrospun nanofibers, which in turn increased the adhesion properties. The work demonstrates that the plasma-electrospinning hybrid process of nanofiber mats is a promising method to prepare durable functional materials.
Journal of Polymer Science Part B: Polymer Physics, 2011
... Fiber and Polymer Science Program, Department of Textile Engineering, Chemistry and Science, ... more ... Fiber and Polymer Science Program, Department of Textile Engineering, Chemistry and Science, North Carolina State University, Raleigh, North Carolina 27695-8301. Publication History. ... 18 Demir, MM; Yilgor, I.; Yilgor, E.; Erman, B. Polymer 2002, 43, 3303–3309. ...
Electrospun nylon 6 fiber mats were deposited on woven 50/50 nylon/cotton fabric with the motive ... more Electrospun nylon 6 fiber mats were deposited on woven 50/50 nylon/cotton fabric with the motive of making them into protective material against submicron-level aerosol chemical and biological threats. Polymer solution concentration, electrospinning voltage, and deposition areal densities were varied to establish the relationships of processing-structure-filtration efficiency of electrospun fiber mats. A high barrier efficiency of greater than 99.5% was achieved on electrospun fiber mats without sacrificing air permeability and pressure drop.
The surface of a polyethylene terephthalate (PET) spunbond nonwoven was modified by using atmosph... more The surface of a polyethylene terephthalate (PET) spunbond nonwoven was modified by using atmospheric pressure He/O 2 plasma treatment. Accessibility of the modified PET nonwoven has been investigated in terms of crystallinity, surface chemical composition, hydrophilicity, and dye uptake. Differential scanning calorimetry (DSC) for crystallinity measurement and X-ray photoelectron spectroscopy (XPS) for chemical composition measurement were used. Surface morphology was studied by using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Percentage crystallinity increased due to the deple-tion of amorphous region by plasma etching. Redeposition of etched particles was observed. Oxygen-based functional groups on the surface of PET increase from 27 to about 32% after 90 s exposure. Wettability increases by more than 10 times and moisture regain increases by three times, compared with the untreated sample. Dye uptake was not changed significantly.
... then move to form new crystals or cause small crystals to grow in size; (2) etching creates s... more ... then move to form new crystals or cause small crystals to grow in size; (2) etching creates spacing in the polymer network, allowing for ... when testing the dyeability of PET treated in a vacuum plasma.12 The following sections will further develop the validity of this mechanism. ...
Durable antibacterial Ag/polyacrylonitrile (Ag/PAN) hybrid nanofibers were prepared by atmospheri... more Durable antibacterial Ag/polyacrylonitrile (Ag/PAN) hybrid nanofibers were prepared by atmospheric plasma treatment and electrospinning. Atmospheric helium plasma treatment was first used to reduce the AgNO 3 precursor in pre-electrospinning solutions into metallic silver nanoparticles, followed by electrospinning into continuous and smooth nanofibers with Ag nanoparticles embedded in the matrix. SEM, TEM, and EDX spectra were used to study the structure and surface elemental composition of the nanofibers. Silver nanoparticles, with diameters ranging between 3 and 6 nm, were found to be uniformly dispersed in the nanofiber matrix. The Ag/PAN nanofibers exhibited slow and long-lasting silver ion release, which provided robust antibacterial activity against both Gram-positive Bacillus cereus and Gram-negative Escherichia coli microorganisms.
A multifunctional and durable nanofiber-fabric-layered composite (NFLC) material was prepared by ... more A multifunctional and durable nanofiber-fabric-layered composite (NFLC) material was prepared by depositing electrospun Ag/PAN hybrid nanofibers onto a Nylon/cotton 50: 50 fabric substrate. The NFLCs showed excellent aerosol barrier efficiency and good air/moisture permeability. In addition, they showed excellent antibacterial efficiency by completely inhibiting the growth of both Gram-negative E. coli and Gram-positive S. aureus. The interfacial adhesion between the nanofiber layer and fabric substrate was significantly improved by atmospheric plasma pretreatment of the substrate. The resultant NFLCs showed excellent resistance to peeling, twisting, and flexing forces.
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