Co-reporter:Fang Zhao, Si Chen, Qiaole Hu, Gang Xue, Qingqing Ni, Qiuran Jiang, Yiping Qiu
Separation and Purification Technology 2017 Volume 175() pp:130-139
Publication Date(Web):24 March 2017
DOI:10.1016/j.seppur.2016.11.024
•3D woven fabric filter were fabricated using textured yarns wrapped by AgNPs/PAN nanofiber (NFWY).•NFWYs were positioned in the fabric to suppress the microorganism growth.•NFWYs in the 3D filter were proved to be effective in minimizing fouling.•Flux of 3D filter with NFWY increased 40–50% in a long term operation.Antimicrobial three dimensional (3D) woven fabric filters are fabricated by wrapping the weft yarn with electrospun nanofibers containing 2 wt% silver nanoparticles (AgNPs). For comparison, 3D fabrics with the same structure composed of commercial antimicrobial yarns containing Ag ion and control yarns of the same types are also fabricated. The disk diffusion test shows that the fabrics and the yarns with AgNPs nanofibers and Ag ions suppress the growth of bacterial colonies. A long term filtration performance test show that the fabric filter containing AgNPs has 40–50% higher fluxes and substantially larger flux recovery proportions than those of the corresponding control filter. The scanning electron microscopy and confocal laser scanning microscopy analyses show that the fabric filter with AgNPs nanofibers has the lowest bacterial cell, polysaccharides, and protein clusters on surface and inside the first two layers of the fabric filters. This is achieved with a concentration of antimicrobial agent two orders of magnitude lower than a regular commercial antimicrobial filter, showing the efficiency of using antimicrobial nanofibers in a fabric filter.
Separation and Purification Technology 2017 Volume 177(Volume 177) pp:
Publication Date(Web):28 April 2017
DOI:10.1016/j.seppur.2016.11.054
•Carbon woven fabric supplied with high voltages were used as gas filters.•Filters with high areal density and voltages had a high filtration efficiency.•Filtration efficiency under high voltages decreased first and then leveled off.•Increasing RH raised filtration efficiency and lowered corona inception voltage.Electrostatic precipitation is combined with a carbon fabric filter to develop a novel filtration system with high collection efficiency for submicron particles while maintaining a pressure drop as low as 6–56 Pa. The effects of high voltages on the filtration properties of carbon woven fabric filters are investigated by varying the fabric areal density, face velocity, number of fabric layers, and environmental relative humidity (RH). The filtration performance tests show that the corona initiation voltage applied to carbon woven fabric should be higher than 20 kV in ambient condition, and filtration efficiency increases with the increasing of fabric areal density and supplied voltage. As the face velocity increases from 2 m/min to 4 m/min, the filtration efficiency at 30 and 40 kV decreases 13%. As the face velocity increases from 4 to 8 m/min, the filtration efficiency decreases much less. The filtration efficiency is not significantly influenced by the number of fabric layers but can be increased dramatically with the increasing of RH. The maximum filtration efficiency reaches 99.8% for PM 1.0 at high RH. Meanwhile, the corona inception voltage decreases to 10 kV as the RH increased from 40% to 95%.Download high-res image (104KB)Download full-size image
•Polyimide nanofiber membrane/carbon woven fabric composite hot gas filters were developed.•The maximum filtration efficiency of this novel filter could reach 99.995% for PM 2.5.•The filters could maintain reasonable filtration performance after 7 filtration cycles with repeated back air flushes.•After heat treatment at 260 and 300 °C, this composite filter shows a relatively high filtration efficiency.In this work, hot gas filters composed of polyimide nanofiber membrane sandwiched between carbon woven fabrics are fabricated to capture fine particles of PM 2.5 level. Polyimide (PI) nanofibers with an average diameter of 190 nm are electrospun on supporting carbon fabrics as filtration layers. The filtration performance tests show that the maximum filtration efficiency reaches 99.99% for PM 2.5, while the maximum pressure drop is only 251.86 Pa after continuously testing for 25 min under a constant flow rate of 20 L/min. As the areal density of the PI nanofiber membrane increases, the filtration efficiency increases first and then levels off when the areal density reaches 11.64 g/m2. In regeneration performance test with back air flush at a pressure of 500 KPa, the composite filter maintains a filtration efficiency of 99.99% and a pressure drop of about 410 Pa. After heat treatment at 260 and 300 °C, the composite filter shows a relatively high filtration efficiency while the tensile strength of the carbon fabric does not change significantly.
Co-reporter:Fang Zhao, Fangfang Weng, Gang Xue, Qiuran Jiang, Yiping Qiu
Separation and Purification Technology 2016 Volume 157() pp:17-26
Publication Date(Web):8 January 2016
DOI:10.1016/j.seppur.2015.11.022
•3D woven fabrics with different pore sizes are used as filters in MBR.•The filter with larger pore sizes could maintain a higher flux and lower turbidity.•3D filters have uniform and thinner distribution of foulants on the fabric surfaces.•High porosity 3D filter has a thick, more porous and uniform cake layer.This study investigates the filtration performance of three dimensional (3D) woven fabric filters with various structures in a membrane bioreactor (MBR). Five 3D woven fabrics with the same component materials but different tightness, and a 2D fabric as the control are adopted as filters in a laboratory-scale submerged MBR. In a 6 h operation, the changes of the fluxes and the turbidities of all filters have the same trend and the 3D filter with the highest porosity has the highest flux and similar turbidity as that of the 2D filter while 3D filter with the lowest porosity has the lowest flux. In a one-month operation, the high porosity 3D filter has total amount of treated water about 1.7 times and 2.5 times as much as those through the low porosity 3D fabric and the 2D filter, respectively. Toward the end of the one-month operation, the ranges of the turbidity for the high porosity 3D filter were 1–1.5 NTU and 1.3–2.5 NTU, 1.6–2.2 NTU for low porosity 3D filter and 2D filter, respectively. The fouling analysis shows that high porosity 3D filter has a thick and the low porosity 3D filter has a thin cake layer mainly circumferentially distributed along sealing rubber ring, while the 2D nylon filter surface only covered by a thin and incomplete cake layer. The 3D filter with lower tightness shows in-depth penetration of foulants while the 2D and 3D tightly woven filters have foulants concentrated in the first layer of the fabrics.
Composites Part B: Engineering 2015 Volume 78() pp:331-337
Publication Date(Web):1 September 2015
DOI:10.1016/j.compositesb.2015.03.091
Three dimensional integrated microstrip antenna (3DIMA) can carry the designed load while functioning as an antenna. In this study, the cylindrical conformal single-patch 3DIMAs with various curvatures were designed, simulated, fabricated and tested experimentally using a 3D orthogonal woven glass preform/epoxy resin composite system. The electromagnetic performances of the cylindrical microstrip antennas were analyzed. The simulated and tested results matched well and the return losses of the cylindrical conformal 3DIMAs with radii of curvatures of 60, 45 and 25 mm were less than −10 dB while resonant frequencies and their gain values were significantly influenced by the radius of curvature and the feeding direction. The 3DIMAs with the curvature perpendicular to the feeding directions showed more stable resonant frequencies and larger gain values than those of 3DIMAs with the curvature along their feeding directions.
Co-reporter:Tianqi Gao, Yi Zhao, Guohong Zhou, Yang Han, Yiwen Zheng, Zhongde Shan, David Hui, Fujun Xu, Yiping Qiu
Composites Part B: Engineering 2015 Volume 77() pp:122-128
Publication Date(Web):August 2015
DOI:10.1016/j.compositesb.2015.02.024
•3D carbon fabric reinforced silica matrix composites were fabricated.•A slurry impregnation and hot pressing method was adopted to fabricate the CMC.•Flexural strengths of the 3D CMC were doubled compared with 2D counterparts.•Impact energy absorption of the 3D Cf/SiO2 CMC reached 96.9 kJ/m2.Carbon fiber reinforced fused silica composites exhibit the advantages of excellent mechanical properties, high heat resistance, low thermal expansion and low density, but low impact resistance or toughness. A novel modified slurry impregnation and hot pressing (SIHP) method was adopted to fabricate a new type of three dimensional orthogonal woven structure carbon fiber reinforced silica ceramic matrix composites (3D Cf/SiO2 CMCs) with higher density and lower porosity. Physical characterization, flexural behavior, impact performance and toughening mechanism of the composites were investigated by three-point bending tests, impact tests, and scanning electron microscopy analysis. The 3D Cf/SiO2 CMC showed a higher flexural strength in both warp (201.6%) and weft (263.6%) directions than those of pure SiO2 and failed at a non-brittle mode due to the fiber debonding and pullout, and a delaminated failure of the 3D preform. The maximum impact energy absorption of the 3D Cf/SiO2 CMC was 96.9 kJ/m2, almost 4 times as much as those for typical other carbon fiber reinforced CMCs.
Fibers and Polymers 2015 Volume 16( Issue 10) pp:2158-2164
Publication Date(Web):2015 October
DOI:10.1007/s12221-015-5436-1
In this work, durable electromagnetic interference shielding cotton fabrics were obtained via superhydrophobic finishing with Nafion-MWCNTs coating. Nafion, a perfluorosulfonated polymer, exhibits low surface energy and good dispersing performance for MWCNTs. The uniform distribution of MWCNTs is beneficial for not only forming connective conductive network, which enhances electrical conductivity and shielding performance of the cotton fabric, but also constructing a nano-micrometer dual scale structure, which is necessary for superhydrophobic surface. After 6-cycles of Nafion-MWCNTs deposition, the resultant fabric possesses a favorable shielding effectiveness of 9.0 dB and a water contact angle of 154.6 °. Besides of the satisfied shielding ability and superhydrophobic surface, more importantly, the fabric exhibits good durability in EMI shielding after immersing in water for 96 h or washing with AATCC standard due to the superhydrophobicity and good chemical stability of the Nafion-MWCNTs coating.
Co-reporter:Changhuan Zhang, Yinzheng Liang, Lan Yao, Yiping Qiu
Solid State Ionics 2014 Volume 267() pp:74-79
Publication Date(Web):1 December 2014
DOI:10.1016/j.ssi.2014.09.015
•Ti4 + substituted LiFePO4-CNF composites are prepared.•Ti4 + at Li or Fe site stabilizes crystal structure and decreases charge transfer resistance.•Cycling performance and rate capability are improved without destroying olivine structure of LiFePO4.•Mix-doped nominal LiFe0.96Ti0.02PO4-CNF exhibited optimal electrochemical performance.Binder-free LiFePO4-carbon nanofiber (LiFePO4-CNF) composites and titanium cation (Ti4 +) substituted LiFePO4-CNF composites are prepared by electrospinning and post-thermal treatment. The morphology, structure, carbon content, metal content and electrochemical performance of the materials are characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction (XRD), elemental analysis (EA), inductively coupled plasma emission spectroscopy (ICP), charge–discharge tests, and electrochemical impedance spectroscopy (EIS). The results indicated that the doping Ti4 + at the Li or Fe site could stabilize the crystal structure, decrease charge transfer resistance, enhance lithium ion diffusion velocity, and thus improve the cycling performance and the rate capability of the materials without destroying the olivine structure of LiFePO4. In particular, the mix-doped nominal LiFe0.96Ti0.02PO4-CNF composites exhibited the optimal electrochemical performance. Its first discharge capacity was 144.3 mA h g− 1 with 0.5C.
Co-reporter:Jianfei Xie, Lan Yao, Fujun Xu, Yishuang Li, Zhongde Shan, David Hui, Yiping Qiu
Composites Part B: Engineering 2014 Volume 66() pp:268-275
Publication Date(Web):November 2014
DOI:10.1016/j.compositesb.2014.05.028
A PMR polyimide composite reinforced with three-dimensional (3D) woven basalt fabric is fabricated for medium high temperature applications. The PMR polyimide matrix resin is derived from 4,4′-methylenediamine (MDA), diethyl ester of 3,3′,4,4′-oxydiphthalic (ODPE) and monoethyl ester of Cis-5-norbornene-endo-2,3-dicarboxylic acid (NE). The rheological properties of the PMR polyimide matrix resin are investigated. Based on the curing reaction of the PMR type polyimide and the rheological properties, an optimum two-step fabrication method is proposed. The three dimensional fabric preforms are impregnated with the polyimide resin in a vacuum oven at 70 °C for 1 h followed by removing the solvent and pre-imidization. The composites are then consolidated by an optimized molding procedure. Scanning electron microscopy analysis shows that needle shaped voids are generated in yarns and the void volume fraction is 4.27%. The decomposition temperature and the temperature at 5% weight loss of the composite post-cured at 320 °C for 24 h are 440 °C and 577 °C, respectively. The dielectric constant and the dielectric loss of the composite are measured by circular cavity method at 7–12 GHz. The tensile strength and the modulus in the warp direction of the composite are 436 MPa and 22.7 GPa. The composite shows a layer-by-layer fracture mode in three-point bending test. The flexure strength and modulus in the warp direction of the composite are 673 MPa and 27.1 GPa, respectively.
Co-reporter:Qian Jiang, Xin Wang, Yuntian Zhu, David Hui, Yiping Qiu
Composites Part B: Engineering 2014 Volume 56() pp:408-412
Publication Date(Web):January 2014
DOI:10.1016/j.compositesb.2013.08.064
Carbon nanotubes (CNTs) have high strength and modulus, large aspect ratio, and good electrical and thermal conductivities, which make them attractive for fabricating composite. The poly(biphenyl dianhydride-p-phenylenediamine) (BPDA/PDA) polyimide has good mechanical and thermal performances and is herein used as matrix in unidirectional carbon nanotube composites for the first time. The strength and modulus of the composite increase by 2.73 and 12 times over pure BPDA–PDA polyimide, while its electrical conductivity reaches to 183 S/cm, which is 1018 times over pure polyimide. The composite has excellent high temperature resistance, and its thermal conductivity is beyond what has been achieved in previous studies. The improved properties of the composites are due to the long CNT length, high level of CNT alignment, high CNT volume fraction and good CNT dispersion in polyimide matrix. The composite is promising for applications that require high strength, lightweight, or high electrical and thermal conductivities.
Journal of Materials Science 2013 Volume 48( Issue 22) pp:7869-7874
Publication Date(Web):2013 November
DOI:10.1007/s10853-013-7502-7
Filters used in membrane bioreactors (MBRs) for wastewater treatment are low in filtration efficiency and the filtration process using MBR is relatively expensive, when low turbidity of treated water is required. To improve the filtration efficiency, three dimensional (3D) orthogonal woven fabrics with textured weft yarns are developed as a filter media used in MBR. Compared with a regular high-density two dimensional fabric filter, the 3D filter with multilayer and tortuous porous structure allows for 1–3 times higher flux and two times more filtered amount of wastewater in 30 days, while still maintaining a stable effluence turbidity and COD removal efficiency. The potential of applying the novel 3D woven filter in MBR for efficient wastewater treatment is proved.
Composites Part B: Engineering 2013 Volume 53() pp:342-346
Publication Date(Web):October 2013
DOI:10.1016/j.compositesb.2013.05.043
In this study, a new method is introduced for fabricating carbon nanotube (CNT) paper, in which the solvent is sprayed on the CNT sheet while it is wound on a rotating mandrel. As the solvent evaporated, the capillary force pulls CNT closer together, resulting in a CNT paper with a high degree of alignment and a high packing density. Three batches of multi-walled CNTs with different wall thicknesses, tube diameters and lengths are utilized for synthesizing highly oriented CNT papers. It is found that CNTs with smallest diameter of 8 nm form strongest CNT paper with a tensile strength of 563 MPa and a tensile modulus of 15 GPa, while that made with CNTs of 10 nm diameter shows the highest electrical conductivity of 5.5 × 104 S/m.
A three-dimensionally integrated microstrip antenna (3DIMA) is a microstrip antenna woven into the three-dimensional woven composite for load bearing while functioning as an antenna. In this study, the effect of weaving direction of conductive yarns on electromagnetic performance of 3DIMAs are investigated by designing, simulating and experimental testing of two microstrip antennas with different weaving directions of conductive yarns: one has the conductive yarns along the antenna feeding direction (3DIMA-Exp1) and the other has the conductive yarns perpendicular the antenna feeding direction (3DIMA-Exp2). The measured voltage standing wave ratio (VSWR) of 3DIMA-Exp1 was 1.4 at the resonant frequencies of 1.39 GHz; while that of 3DIMA-Exp2 was 1.2 at the resonant frequencies of 1.35 GHz. In addition, the measured radiation pattern of the 3DIMA-Exp1 has smaller back lobe and higher gain value than those of the 3DIMA-Exp2. This result indicates that the waving direction of conductive yarns may have a significant impact on electromagnetic performance of textile structural antennas.
In order to improve the interfacial adhesion property between PBO fiber and epoxy, the surface modification effects of PBO fiber treated by atmospheric pressure plasma jet (APPJ) in different time, atmosphere and moisture regain (MR) were investigated. The fiber surface morphology, functional groups, surface wettability for control and plasma treated samples were analyzed by scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and water contact angle measurements, respectively. Meanwhile, the fiber interfacial shear strength (IFSS), representing adhesion property in epoxy, was tested using micro-bond pull-out test, and single fiber tensile strength was also tested to evaluate the mechanical performance loss of fibers caused by plasma treatment. The results indicated that the fiber surface was etched during the plasma treatments, the fiber surface wettability and the IFSS between fiber and epoxy had much improvement due to the increasing of surface energy after plasma treatment, the contact angle decreased with the treatment time increasing, and the IFSS was improved by about 130%. The processing atmosphere could influence IFSS significantly, and moisture regains (MR) of fibers also played a positive role on improving IFSS but not so markedly. XPS analysis showed that the oxygen content on fiber surface increased after treatment, and CO, OCO groups were introduced on fiber surface. On the other hand, the observed loss of fiber tensile strength caused by plasma treatment was not so remarkable to affect the overall performance of composite materials.
The influence of the He/O2 atmospheric pressure plasma jet pre-treatment on subsequent NaHCO3 desizing of blends of starch phosphate and poly(vinyl alcohol) on cotton fabrics is investigated. Atomic force microscopy and scanning electron microscopy analysis indicate that the surface topography of the samples has significantly changed and the surface roughness increases with an increase in plasma exposure time. X-ray photoelectron spectroscopy analysis shows that a larger number of oxygen-containing polar groups are formed on the sized fabric surface after the plasma treatment. The results of the percent desizing ratio (PDR) indicate that the plasma pretreatment facilitated the blended sizes removal from the cotton fabrics in subsequent NaHCO3 treatment and the PDR increases with prolonging plasma treatment time. The plasma technology is a promising pretreatment for desizing of blended sizes due to dramatically reduced desizing time.
The existence of moisture in the substrate material may influence the effect of atmospheric pressure plasma treatment. Our previous study has found that the employment of ethanol pretreatment and plasma treatment can effectively induce hydrophobic surface modification of cellulose fiber to enhance the compatibility to polypropylene (PP) matrix, and this study aims to investigate the influence of fiber moisture regain on the treatment effect of this technique. Ramie fibers with three different moisture regains (MR) (2.5, 6.1 and 23.5%) are pretreated with ethanol followed by atmospheric pressure plasma treatment. Scanning electron microscope (SEM) shows that the 2.5% MR group has the most significant plasma etching effect. X-ray photoelectron spectroscopy (XPS) analysis indicates an increase of CC and a decrease of CO bond in the plasma treated groups, and the largest raise of CC bond for the 2.5% MR group. The water contact angles of the 2.5 and 6.1% MR groups increase, whereas no significant change is showed in the 23.5% MR group. The interfacial shear strengths (IFSS) measured by microbond pull-out test are raised by 44 and 25% when moisture regains are 2.5 and 6.1%, while presented no apparent improvement at high moisture regain of 23.5%. Therefore, it can be concluded that moisture regain has negative influence on the surface hydrophobization of ramie fibers in the improvement of adhesion property to PP matrix.
The influence of He/O2 atmospheric pressure plasma jet (APPJ) treatment on subsequent wet desizing of polyacrylate on PET fabrics was studied in the present paper. Weight loss results indicated that the weight loss increased with an increase of plasma treatment time. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) showed an increased surface roughness after the plasma treatment. SEM also showed that the fiber surfaces were as clean as unsized fibers after 35 s treatment followed by NaHCO3 desizing. X-ray photoelectron spectroscopy (XPS) analysis indicated that oxygen-based functional groups increased for the plasma treated polyacrylate sized fabrics. The percent desizing ratio (PDR) results showed that more than 99% PDR was achieved after 65 s plasma treatment followed by a 5 min NaHCO3 desizing. Compared to conventional wet desizing, indicating that plasma treatment could significantly reduce desizing time.
A conformal load-bearing antenna structure (CLAS) combines the antenna into a composite structure such that it can carry the designed load while functioning as an antenna. Novel microstrip antennas woven into the three dimensional orthogonal woven composite were proposed in our previous study. In order to determine the effect of the space between the conductive wires on the antenna performance, different space ratios of 1.7, 2.3 and 4.6 were considered in the design. Simulation results showed that when the space ratio increased, the frequency shift and return loss of the corresponding antenna became larger. And the antenna had relatively good performance when the space ratio reached 1.7. Two types of antennas were designed and fabricated with the ratio of 1.7 and 1 respectively and both of them obtained agreeable results. It was also demonstrated by the experimental that the orthogonal structure patch antenna had similar radiation pattern with the traditional copper foil microstrip antenna. However, the interlaced patch antenna had large back and side lobes in the radiation pattern because the existence of the curvature of copper wires in interlaced coupons lowered the reflective efficiency of the ground.
Raw cotton fiber is water repellent due to the existence of the water repellent cuticle layer. This study is designed to systematically investigate how He/O2 atmospheric pressure plasma jet (APPJ) treatments influence the wettability and the sizing property of cotton yarns. Water absorption time and adhesion of the sizing agent to the cotton roving are used to evaluate the improvement of wettability and sizing property of the yarn respectively. The water absorption time decreases with the increase of the treatment time and the oxygen flow rate, and the decrease of the jet to substrate distance (JTSD). An optimal water absorption time of 0.8 s is obtained with a treatment time of 20 s, JTSD of 1 mm and O2 flow rate of 0.2 L/min. Scanning electron microscopy (SEM) shows that the etching effect increases with the decrease of the JTSD and X-ray photoelectron spectroscopy (XPS) presents increased oxygen contents after the plasma treatments. An increase of O–CO bonds while a decrease of C–OH/C–O–C bonds are observed when the JTSD is set at 2 mm. However, a remarkable increase of both C–OH/C–O–C and O–CO bonds are achieved when the JTSD is 1 mm. The roving impregnation test results show a nearly doubled adhesion of sizing and a slightly improved breaking elongation, indicating that the plasma treatment does effectively enhance the bonding strength between the fiber and the sizing.
For atmospheric pressure plasma treatments, the results of plasma treatments may be influenced by liquids adsorbed into the substrate. This paper studies the influence of ethylene glycol (EG) pretreatment on the effectiveness of atmospheric plasma jet (APPJ) treatment of ultrahigh molecular weight polyethylene (UHMWPE) fibers with 0.31% and 0.42% weight gain after soaked in EG/water solution with concentration of 0.15 and 0.3 mol/l for 24 h, respectively. Scanning electron microscopy (SEM) shows that the surface of fibers pretreated with EG/water solution does not have observable difference from that of the control group. The X-ray photoelectron spectroscopy (XPS) results show that the oxygen concentration on the surface of EG-pretreated fibers is increased less than the plasma directly treated fibers. The interfacial shear strength (IFSS) of plasma directly treated fibers to epoxy is increased almost 3 times compared with the control group while that of EG-pretreated fibers to epoxy does not change except for the fibers pretreated with lower EG concentration and longer plasma treatment time. EG pretreatment reduces the water contact angle of UHMWPE fibers. In conclusion, EG pretreatment can hamper the effect of plasma treatment of UHMWPE fibers and therefore longer plasma treatment duration is required for fibers pretreated with EG.
This paper studies the influence of moisture absorption of cotton fabrics on the effectiveness of atmospheric pressure plasma jet (APPJ) on desizing of polyvinyl alcohol (PVA). Cotton fabrics with three different moisture regains (MR), namely 1.8%, 7.3%, and 28.4% corresponding to 10%, 65%, and 98% of relative humidity respectively, are treated for 16 s, 32 s, 48 s, and 64 s. X-ray photoelectron spectroscopy analysis indicates that the plasma treated PVA has higher oxygen concentration than the control. Mass loss results show that the fabric with the highest MR has the largest mass loss after 64 s plasma exposure. Solubility measurement reveals that the sample with the lowest MR has the highest desizing efficacy and the percent desizing ratio reaches 96% after 64 s exposure plus a 20 min hot wash, which is shown as clean as the unsized sample through scanning electron microscopy analysis. The yarn tensile strength test results show that APPJ has no negative effect on fabric tensile strength.
The effect of argon/oxygen atmospheric dielectric barrier discharge (DBD) treatment on desizing and scouring of polyvinyl alcohol (PVA) on cotton fabric was studied with respect to the treatment duration of 1, 2, 4 and 6 min. X-ray photoelectron spectroscopy (XPS) analysis indicated that oxygen concentration increased for the plasma treated PVA film. Solubility measurement revealed that plasma treatment increased PVA solubility in hot washing but less effective in cold washing. Scanning electron microscopy (SEM) showed that the fiber surfaces were as clean as unsized fibers after 6 min treatment followed by hot washing. Wickability analysis indicated that the capillary heights of plasma treated fabrics increased significantly as the plasma treatment duration increased. The results of the yarn tensile strength test showed that the plasma treatment did not have a negative effect on fabric tensile strength.
This study is designed to systematically investigate how various factors, such as treatment duration, output power, oxygen gas flux, jet to substrate distance, and moisture regain, influence atmospheric pressure plasma etching rate of polyamide 6 (PA 6) films. The etching rate increased as the output power, oxygen gas flux, and moisture regain increased. As the treatment time increased, the etching rate increased first and then decreased. When the substrate was too close or too far from the nozzle, the etching rate was almost not measurable. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) show an increased surface roughness after the plasma treatment. X-ray photoelectron spectroscopy (XPS) shows a decreased carbon content and an increased oxygen content after the plasma treatment. T-peel strength shows an improved bonding strength between the PA 6 films and an adhesive tape after the plasma treatment.
Polyamide 6 (PA 6) films are treated with helium(He)/CF4 plasma at atmospheric pressure. The samples are treated at different treatment times. The surface modification of the PA 6 films is evaluated by water contact angle, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The etching rate is used to study the etching effect of He/CF4 plasma on the PA 6 films. The T-peel strengths of the control and plasma treated films are measured to show the surface adhesion properties of the films. As the treatment time increases, the etching rate decreases steadily, the contact angle decreases initially and then increases, while the T-peel strength increases first and then decreases. AFM analyses show that the surface roughness increases after the plasma treatment. XPS analyses reveal substantial incorporation of fluorine and/or oxygen atoms to the polymer chains on the film surfaces.
Co-reporter:Lan Yao, Xin Wang, Fei Liang, Ru Wu, Bin Hu, Yani Feng, Yiping Qiu
Composites Science and Technology 2008 Volume 68(7–8) pp:1794-1799
Publication Date(Web):June 2008
DOI:10.1016/j.compscitech.2008.01.014
In order to determine the dielectric constants of 3D orthogonal woven single fiber type (SFT) and hybrid composites from their component dielectric properties, a theoretical model is proposed based on the rule of binary mixtures. The model shows that with the same fiber volume fraction, a component with a larger cross-sectional area perpendicular to the electric field has a greater contribution to the composite dielectric constant. For experimental verification, SFT basalt/epoxy and aramid (Kevlar 129)/epoxy as well as interply and intraply basalt/aramid/epoxy 3D orthogonal woven hybrid composites were fabricated and their dielectric properties were measured using the waveguide method at a frequency range of 8–12 GHz. At 10 GHz, the experimental results agreed well with the calculated results from the model for the SFT composites, while a positive hybrid effect on the dielectric constant was observed for the two hybrid composites.
Co-reporter:X. Wang, B. Hu, Y. Feng, F. Liang, J. Mo, J. Xiong, Y. Qiu
Composites Science and Technology 2008 Volume 68(Issue 2) pp:444-450
Publication Date(Web):February 2008
DOI:10.1016/j.compscitech.2007.06.016
In order to determine the effect of fiber arrangement in 3D woven hybrid composites on their low velocity impact properties, aramid (Kevlar®129), basalt fibers, and epoxy resin were used to fabricate interply hybrid composite in which different yarn types were placed in different layers and intraply hybrid composite in which each layer was composed of two types of alternately arranged yarns. These composites were impact tested at 2 m/s and 3 m/s impact velocities along warp and weft directions. The interply hybrid composite showed higher ductile indices (8–220%), lower peak load (5–45%), and higher specific energy absorption (9–67%) in both warp and weft directions than that of the intraply hybrid composite due to a layer-by-layer fracture mode for the interply hybrid composite.
Three-dimensional aramid woven fabrics were treated with atmospheric pressure plasmas, on one side or both sides to determine the plasma penetration depth in the 3D fabrics and the influences on final composite mechanical properties. The properties of the fibers from different layers of the single side treated fabrics, including surface morphology, chemical composition, wettability and adhesion properties were investigated using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), contact angle measurement and microbond tests. Meanwhile, flexural properties of the composites reinforced with the fabrics untreated and treated on both sides were compared using three-point bending tests. The results showed that the fibers from the outer most surface layer of the fabric had a significant improvement in their surface roughness, chemical bonding, wettability and adhesion properties after plasma treatment; the treatment effect gradually diminished for the fibers in the inner layers. In the third layer, the fiber properties remained approximately the same to those of the control. In addition, three-point bending tests indicated that the 3D aramid composite had an increase of 11% in flexural strength and 12% in flexural modulus after the plasma treatment. These results indicate that composite mechanical properties can be improved by the direct fabric treatment instead of fiber treatment with plasmas if the fabric is less than four layers thick.
In order to determine the relationship between the treatment duration of atmospheric pressure plasma jet (APPJ) and the penetration depth of the surface modification into textile structures, a four-layer stack of polyester woven fabrics was exposed to helium/oxygen APPJ for different treatment durations. The water-absorption time for the top and the bottom sides of each fabric layer was reduced from 200 s to almost 0 s. The capillary flow height for all fabric layers in the stack increased linearly with the treatment duration but the rate of increasing reduced linearly with the fabric layer number. A model for the capillary flow height as a function of treatment duration and the layer number was established based on the experimental data and the maximum penetration depth of the APPJ was predicted for the polyester fabric. The improved wettability of the fabrics was attributed to the enhanced surface roughness due to plasma etching and the surface chemical composition change due to plasma-induced chemical reaction as detected by scanning electron microscopy and X-ray photoelectron spectroscopy, respectively. The surface roughness and the surface chemical composition change diminished as the fabric layer number increased.
One of the main differences between a low-pressure plasma treatment and an atmospheric pressure plasma treatment is that in atmosphere, the substrate material may absorb significant amount of water which may potentially influence the plasma treatment effects. This paper investigates how the moisture absorbed by aramid fibers during the atmospheric pressure plasma treatment influences the aging behavior of the modified surfaces. Kevlar 49 fibers with different moisture regains (MR) (0.5, 3.5 and 5.5%, respectively) are treated with atmospheric pressure plasma jet (APPJ) with helium as the carrier gas and oxygen as the treatment gas. Surface wettability and chemical compositions, and interfacial shear strengths (IFSS) to epoxy for the aramid fibers in all groups are determined using water contact angle measurements, X-ray photoelectron spectroscopy (XPS), and micro-bond pull out tests, respectively. Immediately after the plasma treatment, the treated fibers have substantially lower water contact angles, higher surface oxygen and nitrogen contents, and larger IFSS to epoxy than those of the control group. At the end of 30 day aging period, the fibers treated with 5.5% moisture regain had a lower water contact angle and more polar groups on the fiber surface, leading to 75% improvement of IFSS over the control fibers, while those for the 0.5 and 3.5% moisture regain groups were only 30%.
Journal of Materials Science 2007 Volume 42( Issue 16) pp:6494-6500
Publication Date(Web):2007 August
DOI:10.1007/s10853-007-1534-9
Aramid/glass hybrid composites with three different stacking sequences and their corresponding single fiber type composites have been fabricated and their tensile, impact and dielectric properties were investigated. The trend of tensile strength and modulus of the composites followed the rule of mixture (ROM) closely and a small but positive hybrid effect for tensile strength of the hybrid composites was observed. The hybrid composites in general had a higher impact resistance than the single fiber type composites and the hybrid composite in which fiber volume fractions for glass and aramid fiber were the most balanced showed the highest impact ductility. The aramid fiber composite showed a lower dielectric constant and a higher dielectric loss than the glass fiber composites. However, the dielectric constant of the hybrid composites decreased first and then increased as the volume fraction of aramid fiber increased, which did not follow the mixing rule for dielectric constants of compounds. The dielectric loss of the composites increased monotonically as the volume fraction of aramid fiber increased which agreed well with the mixing rule.
![Poly[(1,1',3,3'-tetrahydro-1,1',3,3'-tetraoxo[5,5'-bi-2H-isoindole]-2,2'-diyl)-1,4-phenylene]](http://img.cochemist.com/ccimg/32200/32197-39-0.png)
![Poly[(1,1',3,3'-tetrahydro-1,1',3,3'-tetraoxo[5,5'-bi-2H-isoindole]-2,2'-diyl)-1,4-phenylene]](http://img.cochemist.com/ccimg/32200/32197-39-0_b.png)
