In this study, the effect of heat treatment on the room temperature strength of W-core Si C fiber produced by chemical vapor deposition（CVD） was investigated. Thermal exposure in the temperature range of 900–1000？...In this study, the effect of heat treatment on the room temperature strength of W-core Si C fiber produced by chemical vapor deposition（CVD） was investigated. Thermal exposure in the temperature range of 900–1000？C decreases the strength of the Si C fiber. Fracture morphology analysis indicates that failure initiations predominantly take place at the W-core/Si C interface. A reaction layer that formed at the W-core/Si C interface during thermal exposure degraded the fiber strength and an empirical linear relationship of strength vs thickness of the reaction layer can be obtained. The kinetics of the growth of the W-core/Si C reaction layer were determined.展开更多
Comparing to some other fibers,the mechanical andsome physical properties of banana fiber,constituent ofbanana fiber have been studied in this paper,mean-while,for improving some characteristics of banana fi-ber,the c...Comparing to some other fibers,the mechanical andsome physical properties of banana fiber,constituent ofbanana fiber have been studied in this paper,mean-while,for improving some characteristics of banana fi-ber,the chemical treatments were used to modify the fi-ber.The results show that the coarse and brittle bananafiber,will be difficult to process in traditional spinningsystem.展开更多
A three-dimensional electrochemical oxidation （3D-EC） reactor with introduction of activated carbon （AC） as particle micro-electrodes was apphed for the advanced treatment of secondary wastewater effluent of a wet...A three-dimensional electrochemical oxidation （3D-EC） reactor with introduction of activated carbon （AC） as particle micro-electrodes was apphed for the advanced treatment of secondary wastewater effluent of a wet-spun acrylic fiber manufacturing plant. Under the optimized conditions （current density of 500 A/m2, circulation rate of 5 mL/min, AC dosage of 50 g, and chloride concentration of 1.0 g/L）, the average removal efficiencies of chemical oxygen demand （CODer）, NH3-N, total organic carbon （TOC）, and ultraviolet absorption at 254 nm （UV2s4） of the 3D-EC reactor were 64.5%, 60.8%, 46.4%, and 64.8%, respectively; while the corresponding effluent concentrations of CODcr, NH3-N, TOC, and UV2s4 were 76.6, 20.1, and 42.5 mg/L, and 0.08 Abs/cm, respectively. The effluent concentration of CODer was less than 100 mg/L, which showed that the treated wastewater satisfied the demand of the integrated wastewater discharge standard （GB 8978-1996）. The 3D-EC process remarkably improved the treatment efficiencies with synergistic effects for CODer, NH3-N, TOC, and UV2s4 during the stable stage of 44.5%, 38.8%, 27.2%, and 10.9%, respectively, as compared with the sum of the efficiencies of a two-dimensional electrochemical oxidation （2D-EC） reactor and an AC adsorption process, which was ascribed to the numerous micro-electrodes of AC in the 3D-EC reactor. Gas chromatography mass spectrometry （GC-MS） analysis revealed that electro- chemical treatment did not generate more toxic organics, and it was proved that the increase in acute biotoxicity was caused primarily by the production of free chlorine.展开更多
The water repellence and mechanical properties of the gelatin/Ce（Ⅲ） fiber（GCe fiber） were improved by heat treatment,which was an easy and non-toxic method.The microscopic morphology,mechanical properties,antibac...The water repellence and mechanical properties of the gelatin/Ce（Ⅲ） fiber（GCe fiber） were improved by heat treatment,which was an easy and non-toxic method.The microscopic morphology,mechanical properties,antibacterial activity,and cell culture of the GCe fibers by heat treatment（HGCe fiber） were investigated.It was found that the water repellence and mechanical properties of the HGCe fibers increased significantly along with temperature increase.SEM observation showed that HGCe fibers had a fairly smooth surface and a compact structure.Detailed characterization revealed that the HGCe fibers exhibited similar antibacterial activity with the GCe fibers against Staphylococcus aureus.In addition,the results of cell culture by morphological assessment and methylthiazolyl tetrazolium assay（MTT assay） indicated the good biocompatibility of GCe fibers.Therefore,the HGCe fibers could be a promising candidate biomaterial for biomedicine applications.展开更多
The relationship between property and structure of poly( p-phenylene terephthalamide)( PPTA) was investigated for the purpose of obtaining products with better performance. PPTA fiber subjected to heat treatment under...The relationship between property and structure of poly( p-phenylene terephthalamide)( PPTA) was investigated for the purpose of obtaining products with better performance. PPTA fiber subjected to heat treatment under different conditions was intensively studied. Simultaneous wide-angle X-ray diffraction( WAXD) technique was introduced to study the changes of crystal structure. It was found that the tensile modulus was strongly sensitive to the levels of temperature and tension. The structure parameters including crystal size and crystal orientation after heat treatment evolve similarly to the tensile modulus,indicating a direct structure-property relationship. The lattic c-dimension increases after heat treatment and is greatly affected by the tension. An optimal temperature can be found around 400 ℃,where big change can happen in the crystal structure due to α-relaxation in the crystal region as supported in dynamic mechanical analysis( DMA).展开更多
The corn husks were usually discarded as useless materials,after alkali treatment from which the corn husk fiber was obtained. The corn husk fiber included half degumming corn husk bundle fiber and corn husk single fi...The corn husks were usually discarded as useless materials,after alkali treatment from which the corn husk fiber was obtained. The corn husk fiber included half degumming corn husk bundle fiber and corn husk single fiber. This study found that corn husk single fiber was a kind of cellulose fiber,and was obtained with the fully alkali treatment technique,the process of which was NaOH concentration 0.15 g/mL,temperature at 80℃,and reaction time about 2.5 h. The morphologies of corn husk single fibers presented nature convolutions along with the fiber axis. They were closed at both ends,and they had a pentagram cavity and oval-shaped crosssection. They were flat shape,the fineness of the fibers was close to cotton fiber,and the mechanical properties of the fibers were similar to hemp fiber. So the corn husk fibers could be predicted that they could be used in textile industry because their properties were very close to cotton fiber or flax fiber.展开更多
The development of surface acidity on rayon-based carbon fibers during mild electrochemical treatment was investigated. Conductimetric titration was the primary method used to investigate the functionalities on the ca...The development of surface acidity on rayon-based carbon fibers during mild electrochemical treatment was investigated. Conductimetric titration was the primary method used to investigate the functionalities on the carbon fiber surface. The acidity on the surface of the untreated carbon fiber was very low, while for the treated fibers, the acidity increased significantly.Moreover, with the treatment extent proceeded, the acidity on the fiber surface also increased. SEM analysis shows electrochemical treatment under intense treatment degree caused considerable etch on the fiber surface.Cavities and grooves can be observed on the surface via the SEM microphotograph. While in a more mild treatment, electrochemical treatment didn't cause great etch on the surface of the fiber.展开更多
Catalysis and regeneration efficiency of granular activated carbon （GAC） and activated carbon fiber （ACF） were investigated in a non-equilibrium plasma water treatment reactor with a combination of pulsed streamer...Catalysis and regeneration efficiency of granular activated carbon （GAC） and activated carbon fiber （ACF） were investigated in a non-equilibrium plasma water treatment reactor with a combination of pulsed streamer discharge and GAC or ACF. The experimental results show that the degradation efficiency of methyl orange （MO） by the combined treatment can increase 22% （for GAC） and 24% （for ACF） respectively compared to pulsed discharge treatment alone, indicating that the combined treatment has a synergetic effect. The MO degradation efficiency by the combined treatment with pulsed discharge and saturated GAC or ACF can increase 12% and 17% respectively compared to pulsed discharge treatment alone. Both GAC and ACF show catalysis and the catalysis of ACF is prominent. Meanwhile, the regeneration of GAC and ACF are realized in this process. When H202 is introduced into the system, the utilization efficiency of ozone and ultraviolet light is improved and the regeneration efficiency of GAC and ACF is also increased.展开更多
The aim of this study is to investigate the effect of chemical treatment method on the properties of Posidonia fibers. The chemical treatment which is carried out is a combined hydrogen peroxide and sodium hydroxide t...The aim of this study is to investigate the effect of chemical treatment method on the properties of Posidonia fibers. The chemical treatment which is carried out is a combined hydrogen peroxide and sodium hydroxide treatment. First, an investigation of the treatment processes was undertaken. Secondly, the physical properties (linear density, diameter and ratio length per diameter), the mechanical properties (tenacity, elongation) and chemical properties (FT-IR spectra and X ray diffraction) of posidonia fibers were investigated. The optimum operating conditions were identified using a factorial design.展开更多
A newly developed atmospheric pressure dielectric barrier discharge （DBD） plasma treatment system （PLA-PLA） was used in this study. The discharge is characterized by electrical analysis and optical emission spectr...A newly developed atmospheric pressure dielectric barrier discharge （DBD） plasma treatment system （PLA-PLA） was used in this study. The discharge is characterized by electrical analysis and optical emission spectroscopy （OES）. The characters of the discharge were found to change systematically with an increase of applied voltage and variation of flow ratio of O2/Ar in the plasma. The OES analysis revealed that the relatively weak spectrum line can be detected beyond a certain applied power value. It is also found that the emission intensity of main species in the discharge spectrum will be enhanced with the increase of applied power. To improve the wettability, poly （ethylene terephtalate） （PET） fiber was treated in this system. The surface morphology and properties of fiber after plasma treatment were investigated by both scanning electron microscope （SEM） and contact angle measurement.展开更多
Tribological properties of polytetrafluoroethylene （PTFE） composites filled with differently surface treated carbon fibers （CF）, sliding against GCr15 steel under dry sliding conditions, were investigated on a blo...Tribological properties of polytetrafluoroethylene （PTFE） composites filled with differently surface treated carbon fibers （CF）, sliding against GCr15 steel under dry sliding conditions, were investigated on a block-on-ring M-2000 tribometer. Experimental results reveal that rare earths （RE） surface treatment reduces the friction and wear of CF-reinforced PTFE （CF/PTFE） composites. Scanning electron microscopy （SEM） investigation of worn surfaces of CF/PTFE composites shows that cracks or pores are visible on the worn surfaces of untreated and air-oxidated composite, while no crack and very few pores present on the worn surface of RE- treated composite. The fiber-friction-angling effect makes carbon fibers angled and oriented along the frictional shearing force, and finally parallel to the friction surface, which makes interracial adhesion become a key factor to tribological properties of CF/PTFE composite. With strong interfacial adhesion between carbon fiber and PTFE after RE surface treatment, carbon fibers are not easily detachable from the PTFE matrix in the process of fiber-friction-angling, which prevents the rubbing-off of PTFE, and accordingly improves the friction and wear properties of the composite.展开更多
In this paper the mechanism producing scrooping sound has been discussedtheoretically.It has been recognized that the continuous stick-slip vibrationhaving a certain period and the bigger △E(△E——enery released by ...In this paper the mechanism producing scrooping sound has been discussedtheoretically.It has been recognized that the continuous stick-slip vibrationhaving a certain period and the bigger △E(△E——enery released by stick-slipvibration at one time)are the requisite and surfficient conditions producingscrooping sound.For fiber sample,its surface properties and internal structureare two principal factors influencing scrooping sound. Considering the surface properties of polyester fiber after scrooping treatmentare the synthetic reflection of the properties used treatment reagents and thesurface properties of the fiber,how selecting proper reagents for scroopingtreatment would be the key factor influencing the scrooping effect.Sometreatment solutions having better scrooping effect have been obtained in the paper. In order to cause better scrooping effect,not only the treatment reagent andsurface properties of the fiber,but also the internal structure of the fiber must beconsidered,It has been shown in展开更多
Carbon fibers （CF） were surface treated with air-oxidation and rare earths （RE）, respectively. The effect of RE surface treatment on tensile strength and tribological properties of CF reinforced polytetrafluoroeth...Carbon fibers （CF） were surface treated with air-oxidation and rare earths （RE）, respectively. The effect of RE surface treatment on tensile strength and tribological properties of CF reinforced polytetrafluoroethylene （PTFE） composites was invest/gated. Experimental results revealed that RE was superior to air ox/dation in improving the tensile strength, elongation, and the tensile modulus of CF reinforced PTFE （CF/PTFE） composite. Compared to the untreated and air-oxidated CF/PTFE composite, the RE treated composite had the lowest friction coefficient and specific wear rate under a given applied load and reciprocating sliding frequency. The RE treatment effectively improved the interfacial adhesion between CF and PTFE. With strong interfacial coupling, the carbon fibers carried most of the load, and direct contact and adhesion between PTFE and the counterpart were reduced, accordingly the friction and wear properties of the composite were improved.展开更多
Defatted rice bran dietary fiber (DRBDF) was modified by micronization, ultrasound, microwave and extrusion cooking. We investigated the impacts of these physical treatments on the fermentation ability and bile salts ...Defatted rice bran dietary fiber (DRBDF) was modified by micronization, ultrasound, microwave and extrusion cooking. We investigated the impacts of these physical treatments on the fermentation ability and bile salts binding capacity of DRBDF. In-vitro fermentation by human fecal bacteria of modified fibers showed that the major fermentation products were propionic, acetate and butyrate acid. Fermentation of extruded fiber gave the highest amounts of propionic and acetic acid 135.76 and 25.45 mmol/L respectively, while, the fermented product with microwaved fiber had the highest butyric acid content (10.75 mmol/L). The amount of short-chain fatty acid increased from 12 h to 24 h and propionic acid was the predominant. On the other hand,in-vitrobile salts binding showed that extruded fiber had higher affinity with sodium deoxycholate and sodium chenodeoxycholate (66.14% and 30.25% respectively) while microwaved fiber exhibited the highest affinity with sodium taurocholate (14.38%). In the light of obtained results we can affirmed that these physical treatments significantly improved the fermentation products and bile salts binding capacity of DRBDF. Extrusion compared to the other physical treatment methods used in this study has greatly and positively influenced the fermentation and bile binding capacity of DRBDF.展开更多
Combined nitric acid oxidation method and polyaniline （PANI）-coated method were applied to modify the surface properties of short carbon fibers （SCF）. The electrical and mechanical properties of acrylic coatings w...Combined nitric acid oxidation method and polyaniline （PANI）-coated method were applied to modify the surface properties of short carbon fibers （SCF）. The electrical and mechanical properties of acrylic coatings with 50 wt pct PANI-coated carbon fiber were investigated by using scanning electron microscope （SEM）, UV-Vis spectrophotometer, four-probe method and the coaxial cable method. The results of the pH measurement and XPS （X-ray photoelectron spectroscopy） patterns showed that the oxygen functional groups, such as -OH and -COOH, were attached on the carbon fiber surfaces after oxidation treatment. The XPS analysis of PANl-coated oxidized SCF （PAOSCF） revealed that PANI may bond on the surface of oxidized SCF with chemical bonds. SEM images and surface roughness analyses showed that PANl-coated layer changed the surface morphology. Compared with SCF/acrylic coating, the surface resistivity of PAOSCF/acrylic coating decreased from17.1 to 5.3 Ω/sq and the shielding efficiency （SE） value increased from 1.54 to 23.3 dB.展开更多
This study presents the composites prepared by melt blending based on high-density polyethylene, containing various amounts of kenaf fiber loadings and polyethylene-grafted maleic anhydride (PE-g-MA) in an internal mi...This study presents the composites prepared by melt blending based on high-density polyethylene, containing various amounts of kenaf fiber loadings and polyethylene-grafted maleic anhydride (PE-g-MA) in an internal mixer were prepared and investigated. Fourier transform infrared spectroscopy was used to characterize both untreated and treated ke- naf fibers. A rheological study of the composites showed a high complex viscosity and dynamic shear storage modulus between untreated and treated composites and composites with compatibilizer. A mechanical test showed that the ten- sile strength and tensile modulus were optimal with 20% fiber loading but decreased with 30% fiber loading for both the untreated and treated composites. The composite with PE-g-MA showed an improved mechanical strength. This phenomenon is due to an increase in the interfacial adhesion between the fiber and matrix leading to an improvement in the compatibility of the blend. Treatment of the kenaf fiber improved in the mechanical and impact strengths in com- parison to the untreated kenaf composites. This behavior was supported by a morphology analysis of the fractured sur- faces revealed that strong interfaces were formed on addition of the compatibilizer.展开更多
In this paper, we deals with mechanical performance of resin impregnation with natural fiber and fiber reinforced composites. The effect of the addition of a rein impregnation process on static strength of the injecti...In this paper, we deals with mechanical performance of resin impregnation with natural fiber and fiber reinforced composites. The effect of the addition of a rein impregnation process on static strength of the injection molded composites was investigated by carrying out tensile and banding tests, followed by Scanning electron microscopy (SEM) observation of fiber surface and fracture surface of composites. The tensile strength of natural fiber and natural fiber reinforced composites with resin impregnation method increases with Polyvinyl alcohol (PVA) impregnation. In addition, Phenol resin impregnation recovers fiber tensile strength after alkali treatment. Resin impregnation causes decrease in contact surface area;however, it does not cause decrease in mechanical properties. Our results suggest that the using rein impregnation method has better effect on the mechanical properties of natural fiber reinforced Polypropylene (PP) composites.展开更多
基金the Raman Spectroscopy Laboratory of Institute of Metal Research, Chinese Academy of Sciences for the support in the accomplishment of this paper
文摘In this study, the effect of heat treatment on the room temperature strength of W-core Si C fiber produced by chemical vapor deposition（CVD） was investigated. Thermal exposure in the temperature range of 900–1000？C decreases the strength of the Si C fiber. Fracture morphology analysis indicates that failure initiations predominantly take place at the W-core/Si C interface. A reaction layer that formed at the W-core/Si C interface during thermal exposure degraded the fiber strength and an empirical linear relationship of strength vs thickness of the reaction layer can be obtained. The kinetics of the growth of the W-core/Si C reaction layer were determined.
文摘Comparing to some other fibers,the mechanical andsome physical properties of banana fiber,constituent ofbanana fiber have been studied in this paper,mean-while,for improving some characteristics of banana fi-ber,the chemical treatments were used to modify the fi-ber.The results show that the coarse and brittle bananafiber,will be difficult to process in traditional spinningsystem.
基金supported by the Major Science and Technology Program for Water Pollution Control and Treatment (No. 2012ZX07201002-6)
文摘A three-dimensional electrochemical oxidation （3D-EC） reactor with introduction of activated carbon （AC） as particle micro-electrodes was apphed for the advanced treatment of secondary wastewater effluent of a wet-spun acrylic fiber manufacturing plant. Under the optimized conditions （current density of 500 A/m2, circulation rate of 5 mL/min, AC dosage of 50 g, and chloride concentration of 1.0 g/L）, the average removal efficiencies of chemical oxygen demand （CODer）, NH3-N, total organic carbon （TOC）, and ultraviolet absorption at 254 nm （UV2s4） of the 3D-EC reactor were 64.5%, 60.8%, 46.4%, and 64.8%, respectively; while the corresponding effluent concentrations of CODcr, NH3-N, TOC, and UV2s4 were 76.6, 20.1, and 42.5 mg/L, and 0.08 Abs/cm, respectively. The effluent concentration of CODer was less than 100 mg/L, which showed that the treated wastewater satisfied the demand of the integrated wastewater discharge standard （GB 8978-1996）. The 3D-EC process remarkably improved the treatment efficiencies with synergistic effects for CODer, NH3-N, TOC, and UV2s4 during the stable stage of 44.5%, 38.8%, 27.2%, and 10.9%, respectively, as compared with the sum of the efficiencies of a two-dimensional electrochemical oxidation （2D-EC） reactor and an AC adsorption process, which was ascribed to the numerous micro-electrodes of AC in the 3D-EC reactor. Gas chromatography mass spectrometry （GC-MS） analysis revealed that electro- chemical treatment did not generate more toxic organics, and it was proved that the increase in acute biotoxicity was caused primarily by the production of free chlorine.
基金Project supported by the Foundation of State Key Laboratory of Chemical Resource Engineering (2008-2009)
文摘The water repellence and mechanical properties of the gelatin/Ce（Ⅲ） fiber（GCe fiber） were improved by heat treatment,which was an easy and non-toxic method.The microscopic morphology,mechanical properties,antibacterial activity,and cell culture of the GCe fibers by heat treatment（HGCe fiber） were investigated.It was found that the water repellence and mechanical properties of the HGCe fibers increased significantly along with temperature increase.SEM observation showed that HGCe fibers had a fairly smooth surface and a compact structure.Detailed characterization revealed that the HGCe fibers exhibited similar antibacterial activity with the GCe fibers against Staphylococcus aureus.In addition,the results of cell culture by morphological assessment and methylthiazolyl tetrazolium assay（MTT assay） indicated the good biocompatibility of GCe fibers.Therefore,the HGCe fibers could be a promising candidate biomaterial for biomedicine applications.
基金National Basic Research Program of China(973 Program)(No.2011CB606103)National High-Tech Research and Development Program of China(863 Program)(No.2012AA03212)the Fundamental Research Funds for the Central Universities,China(No.11D10625)
文摘The relationship between property and structure of poly( p-phenylene terephthalamide)( PPTA) was investigated for the purpose of obtaining products with better performance. PPTA fiber subjected to heat treatment under different conditions was intensively studied. Simultaneous wide-angle X-ray diffraction( WAXD) technique was introduced to study the changes of crystal structure. It was found that the tensile modulus was strongly sensitive to the levels of temperature and tension. The structure parameters including crystal size and crystal orientation after heat treatment evolve similarly to the tensile modulus,indicating a direct structure-property relationship. The lattic c-dimension increases after heat treatment and is greatly affected by the tension. An optimal temperature can be found around 400 ℃,where big change can happen in the crystal structure due to α-relaxation in the crystal region as supported in dynamic mechanical analysis( DMA).
基金Science and Technology Project of Fujian Province,China(No.2015H0030)Fujian Provincial Universities Projects,China(No.JK2014042)
文摘The corn husks were usually discarded as useless materials,after alkali treatment from which the corn husk fiber was obtained. The corn husk fiber included half degumming corn husk bundle fiber and corn husk single fiber. This study found that corn husk single fiber was a kind of cellulose fiber,and was obtained with the fully alkali treatment technique,the process of which was NaOH concentration 0.15 g/mL,temperature at 80℃,and reaction time about 2.5 h. The morphologies of corn husk single fibers presented nature convolutions along with the fiber axis. They were closed at both ends,and they had a pentagram cavity and oval-shaped crosssection. They were flat shape,the fineness of the fibers was close to cotton fiber,and the mechanical properties of the fibers were similar to hemp fiber. So the corn husk fibers could be predicted that they could be used in textile industry because their properties were very close to cotton fiber or flax fiber.
文摘The development of surface acidity on rayon-based carbon fibers during mild electrochemical treatment was investigated. Conductimetric titration was the primary method used to investigate the functionalities on the carbon fiber surface. The acidity on the surface of the untreated carbon fiber was very low, while for the treated fibers, the acidity increased significantly.Moreover, with the treatment extent proceeded, the acidity on the fiber surface also increased. SEM analysis shows electrochemical treatment under intense treatment degree caused considerable etch on the fiber surface.Cavities and grooves can be observed on the surface via the SEM microphotograph. While in a more mild treatment, electrochemical treatment didn't cause great etch on the surface of the fiber.
基金National Natural Science Foundation of China(Nos.20576079,20776159)
文摘Catalysis and regeneration efficiency of granular activated carbon （GAC） and activated carbon fiber （ACF） were investigated in a non-equilibrium plasma water treatment reactor with a combination of pulsed streamer discharge and GAC or ACF. The experimental results show that the degradation efficiency of methyl orange （MO） by the combined treatment can increase 22% （for GAC） and 24% （for ACF） respectively compared to pulsed discharge treatment alone, indicating that the combined treatment has a synergetic effect. The MO degradation efficiency by the combined treatment with pulsed discharge and saturated GAC or ACF can increase 12% and 17% respectively compared to pulsed discharge treatment alone. Both GAC and ACF show catalysis and the catalysis of ACF is prominent. Meanwhile, the regeneration of GAC and ACF are realized in this process. When H202 is introduced into the system, the utilization efficiency of ozone and ultraviolet light is improved and the regeneration efficiency of GAC and ACF is also increased.
文摘The aim of this study is to investigate the effect of chemical treatment method on the properties of Posidonia fibers. The chemical treatment which is carried out is a combined hydrogen peroxide and sodium hydroxide treatment. First, an investigation of the treatment processes was undertaken. Secondly, the physical properties (linear density, diameter and ratio length per diameter), the mechanical properties (tenacity, elongation) and chemical properties (FT-IR spectra and X ray diffraction) of posidonia fibers were investigated. The optimum operating conditions were identified using a factorial design.
文摘A newly developed atmospheric pressure dielectric barrier discharge （DBD） plasma treatment system （PLA-PLA） was used in this study. The discharge is characterized by electrical analysis and optical emission spectroscopy （OES）. The characters of the discharge were found to change systematically with an increase of applied voltage and variation of flow ratio of O2/Ar in the plasma. The OES analysis revealed that the relatively weak spectrum line can be detected beyond a certain applied power value. It is also found that the emission intensity of main species in the discharge spectrum will be enhanced with the increase of applied power. To improve the wettability, poly （ethylene terephtalate） （PET） fiber was treated in this system. The surface morphology and properties of fiber after plasma treatment were investigated by both scanning electron microscope （SEM） and contact angle measurement.
基金the National Natural Science Foundation of China (No.50275093)
文摘Tribological properties of polytetrafluoroethylene （PTFE） composites filled with differently surface treated carbon fibers （CF）, sliding against GCr15 steel under dry sliding conditions, were investigated on a block-on-ring M-2000 tribometer. Experimental results reveal that rare earths （RE） surface treatment reduces the friction and wear of CF-reinforced PTFE （CF/PTFE） composites. Scanning electron microscopy （SEM） investigation of worn surfaces of CF/PTFE composites shows that cracks or pores are visible on the worn surfaces of untreated and air-oxidated composite, while no crack and very few pores present on the worn surface of RE- treated composite. The fiber-friction-angling effect makes carbon fibers angled and oriented along the frictional shearing force, and finally parallel to the friction surface, which makes interracial adhesion become a key factor to tribological properties of CF/PTFE composite. With strong interfacial adhesion between carbon fiber and PTFE after RE surface treatment, carbon fibers are not easily detachable from the PTFE matrix in the process of fiber-friction-angling, which prevents the rubbing-off of PTFE, and accordingly improves the friction and wear properties of the composite.
文摘In this paper the mechanism producing scrooping sound has been discussedtheoretically.It has been recognized that the continuous stick-slip vibrationhaving a certain period and the bigger △E(△E——enery released by stick-slipvibration at one time)are the requisite and surfficient conditions producingscrooping sound.For fiber sample,its surface properties and internal structureare two principal factors influencing scrooping sound. Considering the surface properties of polyester fiber after scrooping treatmentare the synthetic reflection of the properties used treatment reagents and thesurface properties of the fiber,how selecting proper reagents for scroopingtreatment would be the key factor influencing the scrooping effect.Sometreatment solutions having better scrooping effect have been obtained in the paper. In order to cause better scrooping effect,not only the treatment reagent andsurface properties of the fiber,but also the internal structure of the fiber must beconsidered,It has been shown in
基金Project supported by the National Natural Science Foundation of China (50275093)
文摘Carbon fibers （CF） were surface treated with air-oxidation and rare earths （RE）, respectively. The effect of RE surface treatment on tensile strength and tribological properties of CF reinforced polytetrafluoroethylene （PTFE） composites was invest/gated. Experimental results revealed that RE was superior to air ox/dation in improving the tensile strength, elongation, and the tensile modulus of CF reinforced PTFE （CF/PTFE） composite. Compared to the untreated and air-oxidated CF/PTFE composite, the RE treated composite had the lowest friction coefficient and specific wear rate under a given applied load and reciprocating sliding frequency. The RE treatment effectively improved the interfacial adhesion between CF and PTFE. With strong interfacial coupling, the carbon fibers carried most of the load, and direct contact and adhesion between PTFE and the counterpart were reduced, accordingly the friction and wear properties of the composite were improved.
文摘Defatted rice bran dietary fiber (DRBDF) was modified by micronization, ultrasound, microwave and extrusion cooking. We investigated the impacts of these physical treatments on the fermentation ability and bile salts binding capacity of DRBDF. In-vitro fermentation by human fecal bacteria of modified fibers showed that the major fermentation products were propionic, acetate and butyrate acid. Fermentation of extruded fiber gave the highest amounts of propionic and acetic acid 135.76 and 25.45 mmol/L respectively, while, the fermented product with microwaved fiber had the highest butyric acid content (10.75 mmol/L). The amount of short-chain fatty acid increased from 12 h to 24 h and propionic acid was the predominant. On the other hand,in-vitrobile salts binding showed that extruded fiber had higher affinity with sodium deoxycholate and sodium chenodeoxycholate (66.14% and 30.25% respectively) while microwaved fiber exhibited the highest affinity with sodium taurocholate (14.38%). In the light of obtained results we can affirmed that these physical treatments significantly improved the fermentation products and bile salts binding capacity of DRBDF. Extrusion compared to the other physical treatment methods used in this study has greatly and positively influenced the fermentation and bile binding capacity of DRBDF.
文摘Combined nitric acid oxidation method and polyaniline （PANI）-coated method were applied to modify the surface properties of short carbon fibers （SCF）. The electrical and mechanical properties of acrylic coatings with 50 wt pct PANI-coated carbon fiber were investigated by using scanning electron microscope （SEM）, UV-Vis spectrophotometer, four-probe method and the coaxial cable method. The results of the pH measurement and XPS （X-ray photoelectron spectroscopy） patterns showed that the oxygen functional groups, such as -OH and -COOH, were attached on the carbon fiber surfaces after oxidation treatment. The XPS analysis of PANl-coated oxidized SCF （PAOSCF） revealed that PANI may bond on the surface of oxidized SCF with chemical bonds. SEM images and surface roughness analyses showed that PANl-coated layer changed the surface morphology. Compared with SCF/acrylic coating, the surface resistivity of PAOSCF/acrylic coating decreased from17.1 to 5.3 Ω/sq and the shielding efficiency （SE） value increased from 1.54 to 23.3 dB.
文摘This study presents the composites prepared by melt blending based on high-density polyethylene, containing various amounts of kenaf fiber loadings and polyethylene-grafted maleic anhydride (PE-g-MA) in an internal mixer were prepared and investigated. Fourier transform infrared spectroscopy was used to characterize both untreated and treated ke- naf fibers. A rheological study of the composites showed a high complex viscosity and dynamic shear storage modulus between untreated and treated composites and composites with compatibilizer. A mechanical test showed that the ten- sile strength and tensile modulus were optimal with 20% fiber loading but decreased with 30% fiber loading for both the untreated and treated composites. The composite with PE-g-MA showed an improved mechanical strength. This phenomenon is due to an increase in the interfacial adhesion between the fiber and matrix leading to an improvement in the compatibility of the blend. Treatment of the kenaf fiber improved in the mechanical and impact strengths in com- parison to the untreated kenaf composites. This behavior was supported by a morphology analysis of the fractured sur- faces revealed that strong interfaces were formed on addition of the compatibilizer.
文摘In this paper, we deals with mechanical performance of resin impregnation with natural fiber and fiber reinforced composites. The effect of the addition of a rein impregnation process on static strength of the injection molded composites was investigated by carrying out tensile and banding tests, followed by Scanning electron microscopy (SEM) observation of fiber surface and fracture surface of composites. The tensile strength of natural fiber and natural fiber reinforced composites with resin impregnation method increases with Polyvinyl alcohol (PVA) impregnation. In addition, Phenol resin impregnation recovers fiber tensile strength after alkali treatment. Resin impregnation causes decrease in contact surface area;however, it does not cause decrease in mechanical properties. Our results suggest that the using rein impregnation method has better effect on the mechanical properties of natural fiber reinforced Polypropylene (PP) composites.
