共查询到20条相似文献,搜索用时 15 毫秒
1.
The surface morphology of the CO2 laser treated grey cotton fabrics was studied which showed a characteristics sponge-like structure on cotton fibres after
treating with CO2 laser irradiation. The laser treatment parameters ranging from 100 to 150 pixel time and 40 to 70 dot per inch (dpi) were
irradiated on the grey cotton fabrics directly and the degree of physical modifications, such as surface morphology, wettability
and fabric strength, were changed accordingly with various laser treatment parameters. The surface morphology, wettability
and tensile strength of cotton fibre treating with laser were evaluated using different instruments, such as Scanning Electron
Microscope (SEM), contact angle meter and tensile strength machine. In spite of creating a sponge-like structure on fibre
surface after treating with laser, the wettability of the samples was highly improved but the tensile strength was decreased. 相似文献
2.
Basalt fibers were surface modified by a new method using nanostructured porous silica aerogel via sol-gel process followed by ambient pressure drying method. FTIR, FE-SEM, and nitrogen adsorption analysis were used for characterization of silica aerogel particles which proved their mesoporous structure with pore size of 7 nm, high porosity and low density. FTIR spectra indicated the formation of silica aerogel on the basalt fibers surface. SEM analysis proved the surface modification of basalt fibers and quantitative measurement showed an increase of 2-fold in the surface roughness compared to unmodified surface fibers. A decrease of 42 % in the density of the surface modified basalt fibers was observed. Also, acoustical properties measurement showed that sound absorption coefficient was increased by 25 %. The obtained results show that silica aerogel structure can affect the physical properties of surface modified basalt fibers. Two silica aerogels with different density and porosity were used in this work. 相似文献
3.
Yibing Cai Dawei Gao Qufu Wei Huili Gu Shi Zhou Fenglin Huang Lei Song Yuan Hu Weidong Gao 《Fibers and Polymers》2011,12(1):145-150
In this work, the pure polyacrylonitrile (PAN) nanofibers and PAN/FeCl3 composite nanofibers were prepared by an electrospinning process. Electrospinning solution properties including viscosity,
surface tension and conductivity, had been measured and combined with the results of Scanning electron microscopy (SEM), Atomic
force microscope (AFM) and Micro Combustion Calorimeter (MCC) to investigate the effects of FeCl3 on the structure, surface morphology and combustion property of electrospun PAN nanofibers, respectively. It was found from
SEM images that the diameters of composite nanofibers were decreased with the addition of FeCl3, which was attributed predominantly to the increased conductivity of the polymer solutions compared to viscosity and surface
tension. The AFM analyses revealed that the surface morphology of electrospun nanofibers changed from smooth and wrinkle-like
structure (without FeCl3) to rough and ridge-like structure (with FeCl3). The results characterized by MCC showed that the loading of FeCl3 decreased the heat release rate (HRR) and improved the combustion property of composite nanofibers. 相似文献
4.
A simple and modified electrospinning technique was utilized to prepare aligned and heat treated Polyacrylonitrile nanofibers by using a rotating drum fixed on top of syringe needles and applying upward hot air flow which can facilitate to heat nanofibers in electrospinning zone. Polyacrylonitrile nanofibers were electrospun from its 14 wt% solution in dimethylformamide under practical conditions. Angular power spectrum analysis showed better fiber alignment with increasing take up speed, although SEM studies demonstrated wider diameters of nanofibers being produced by modified method. The glass transition temperature of all prepared samples were determined between 70 °C and 90 °C using DSC technique. The Quantitative analysis of WAXD patterns has revealed the positive effect of modified method on the degree of crystallization of nanofibers heat treated at higher take up speed. The maximum chain orientation factor of 0.27 was determined for nanofibers collected at linear velocity of 114.5 m/min in the modified set up using Raman Spectroscopy technique. 相似文献
5.
The aim of this study was to investigate the effect of the thermal modification process by hot-press on the wettability and surface roughness characteristics of the eucalyptus wood boards. The roughness measurements, average roughness (Ra), and maximum roughness (Rmax) were taken both parallel and perpendicular to the grain using a fine stylus tracing technique. Contact angle measurements were obtained using a goniometer system connected to a digital camera and computer system. The results showed that surface roughness values of the modified wood boards using a hot-press significantly decreased with increasing press pressure and with decreasing temperature. The contact angle measurements indicated that the thermal modification had a significant influence on the surface wettability of the wood boards. Statistical analyses showed significant differences in the surface roughness and contact angle values of the wood boards following thermal modification. The results acquired in this work provide important information for future research and utilization of the thermally modified wood boards. 相似文献
6.
The presented research deals with modifying the chemical structure of the bioscoured cotton fabric by acrylonitrile, acrylonitrile/acetone, and acrylonitrile/ethanol mixture. The modified cellulose was tested for weight gain, shrinkage, and wicking height and characterized by X-ray diffraction (XRD), thermal analysis (TG/DTA), elemental analysis, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The weight gain and shrinkage % show increased value for modified fabrics. The wicking height increases with addition of solvent. The crystallinity and thermal studies show a significant change. FTIR analysis confirms the modification by the occurrence of -C??N stretching and -CONH2 stretching. The SEM morphology of modified fabric shows uniform swelling of fibers with better smoothness. The AFM topography reveals that the addition of solvent affects the particle size. Clear surface morphology of modified fabric reveals that this processing method can be used for preparation of medical textiles with more swelling. 相似文献
7.
Highly stable coated polyvinylpyrrolidone nanofibers prepared using modified coaxial electrospinning
Jiangang Xie Hairong Mao Deng-Guang Yu Gareth R. Williams Miao Jin 《Fibers and Polymers》2014,15(1):78-83
Hydrophobic polyvinylpyrrolidone (PVP) nanofibers, which is intensely hygroscopic, has been successfully prepared to improve their moisture resistance using a modified coaxial electrospinning process. A stearic acid (SA) solution was exploited as the sheath fluid to coat the fibers. Scanning electron microscopy demonstrated that the SA-coated PVP nanofibers became increasingly small with a rise in the sheath-to-core flow rate ratio; continuing to increase the sheath flow rate beyond a cut-off point resulted in nanofibres with very complicated morphologies. Transmission electron microscope images showed that SA formed a thin layer on the PVP nanofibers, with SA nanoparticles present on the fiber surfaces when a sheath-to-core flow rate ratio of 0.2:0.8 was used. Attenuated total reflectance-Fourier transform infrared spectroscopy verified the coating of SA onto the PVP nanofibers, and also the formation of hydrogen bonds between the SA and PVP molecules. The SA-coated PVP nanofibers were found to have much enhanced moisture resistance over pure PVP fibers. Modified coaxial electrospinning hence comprises a novel and powerful strategy for nanocoating and surface modification of polymer nanofibers. 相似文献
8.
We report a simple and versatile method to prepare hydrophobic composite SiO2 membrane. The electrospun SiO2 membrane was selected due to its good flexibility and thermal stability. The hydrophobic SiO2 membrane was succussfully prepared by simply evaporating a thin polydimethylsiloxane (PDMS) layer on the fiber surface. The characterization results show that the PDMS layer is too thin to be observed. The PDMS coating has no influence on the porous structure of the fibrous membrane, but imparts the good hydrophobicity and oleophilicity to the SiO2 nanofibers. As demonstration, the hydrophobic SiO2-PDMS membrane displays good oil absorption performance from the oil/water mixture, as well as filtration membrane for oil/water separation. Additionally, due to the proper pore size and hydrophobic surface, the SiO2- PDMS membrane shows good waterproof performance and breathability at the same time. 相似文献
9.
《Plant Production Science》2013,16(3):303-313
AbstractMangrove trees have been considered to possess a higher carbon fixation capacity than terrestrial trees although a reliable method to estimate their CO2 fixation capacity has not been established. In this study, net CO2 fixation in above-ground of Rhizophora stylosa was estimated as the difference between photosynthetic absorption and respiratory emission of CO2. In order to estimate these parameters, photosynthetic rates of single-leaves in response to light and temperature and the respiratory rates of leaves and branches in response to temperature were measured. Furthermore, we established a model of diurnal change in temperature. Monthly averages of the diurnal temperature change were used for correcting the CO2 absorption and emission. The effect of temperature modification on the estimation of net CO2 fixation was examined, and the net CO2 fixation capacity estimated with and without temperature modification was compared. Biomass accumulation estimated without temperature modification (i.e. corrected only for the light intensity) was 6.1 tons ha-1 yr-1, while that estimated with temperature modification (i.e. corrected for both light intensity and temperature) was 13.0 tons ha-1 yr-1. A doubling of the estimated values of net CO2 fixation as observed in this study was caused by the decrease in respiratory CO2 emission by half, which results from temperature modification. These findings suggest that temperature modification in gas exchange analysis could improve the accuracy of estimation of the net CO2 fixation capacity. 相似文献
10.
Polystyrene (PS) composites with nanofibrous structure consisting of multi-walled carbon nanotubes (MWCNTs) with 0-10 wt.% of nanofiller have been fabricated via electrospinning technique. The surface morphology and thermal properties of the composites were evaluated by scanning electron microscopy (SEM) and thermo-gravimetric analysis (TGA). The SEM analysis of the composite nanofibers samples revealed that the average diameter of the nanofibers increases with increasing MWCNTs content. The resultant MWCNTs/PS composite nanofibers diameters were in the range of 391±63 to 586±132 nm. The thermal stability of composites was increased after addition of MWCNTs to PS matrix. The electrical conductivity of the composites with different weight percentage of MWCNTs was investigated at room temperature. Electrical conductivity of MWCNTs/PS composite nanofiber followed percolation theory having a percolation threshold V c= 0.45 vol% (~0.75 wt. %) and critical exponent q=1.21. The electrical conductivity and thermal properties confirmed the presence of good dispersion and alignment MWCNTs encapsulated within the electrospun nanofibers. The electromagnetic interference (EMI) shielding effectiveness of the MWCNTs/PS composites was examined in the measurement frequency range of 8.2-12.4 GHz (X-band). The total EMI shielding efficiency of MWCNTs/PS composite nanofibers increased up to 32 dB. The EMI shielding results for MWCNTs/PS composite nanofibers showed that absorption loss was the major shielding mechanism and reflection was the secondary mechanism. The present study has shown the possibility of utilizing MWCNTs/PS composite nanofibers as EMI shielding/absorption materials. 相似文献
11.
《Journal of Crop Improvement》2013,27(1-2):217-244
SUMMARY Since CO2 is a primary input for crop growth, there is interest in how increasing atmospheric CO2 will affect crop productivity and alter cropping system management. Effects of elevated CO2 on grain and residue production will be influenced by crop selection. This field study evaluated soybean [C3; Glycine max(L.) Merr.] and grain sorghum [C4; Sorghum bicolor (L.) Moench.] cropping systems managed under conservation tillage practices and two atmospheric CO2 concentrations (ambient and twice ambient) for three growing seasons. Elevated CO2 increased soybean and sorghum yield by 53% and 17% increase, respectively; reductions in whole plant water use were also greater for soybean than sorghum. These findings suggest that increasing CO2 could improve future food security, especially in soybean production systems. Elevated CO2 increased aboveground residue production by > 35% for both crops; such shifts could complement conservation management by increasing soil surface cover, thereby reducing soil erosion. However, increased residue could negatively impact crop stand establishment and implement effectiveness during tillage operations. Elevated CO2 increased total belowground dry weight for both crops; increased root proliferation may alter soil structural characteristics (e.g., due to increased number and extent of root channels) which could lead to increases in porosity, infiltration rates, and subsequent soil water storage. Nitrate leaching was reduced during the growing season (due to increased N capture by high CO2-grown crops), and also during the fallow period (likely a result of altered decomposition patterns due to increased C:N ratios of the high CO2-grown material). Enhanced crop growth (both above-and be-lowground) under elevated CO2 suggests greater delivery of C to soil, more soil surface residue, and greater percent ground coverage which could reduce soil C losses, increase soil C storage, and help ameliorate the rise in atmospheric CO2. Results from this study suggests that the biodegradability of crop residues and soil C storage may not only be affected by the environment they were produced in but may also be species dependent. To more fully elucidate the relationships between crop productivity, nutrient cycling, and decomposition of plant materials produced in elevated CO2 environments, future studies must address species effects (including use of genetically modified crops) and must also consider other factors such as cover crops, crop rotations, soil series, tillage practices, weed management, and regional climatic differences. 相似文献
12.
Madana Leela Nallappan Mohamed Mahmoud Nasef Teo Ming Ting Arshad Ahmad 《Fibers and Polymers》2018,19(8):1694-1705
Nanofibrous poly(vinylidene fluoride) (PVDF) sheets were produced by electrospinning and grafted with oxirane groups using radiation induced grafting of glycidyl methacrylate (GMA) followed by treatment with N-methyl-D-glucamine (NMDG). The NMDG density in the nanofibers was tuned by optimization of the immobilisation reaction variables using response surface methodology (RSM). The various properties of NMDG-containing nanofibers were evaluated using Fourier-transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The NMDG-containing nanofibers were tested for boron selective removal from solutions. A maximum glucamine density yield of 2.2 mmol/g was obtained at 15 wt%, 87 oC, 64.7 min and 150 % for NMDG concentration, temperature, time and degree of grafting (DG), respectively. The applied procedure incorporating RSM was found to be highly effective in the optimization of covalently immobilised glucamine on the oxirane modified PVDF based-nanofibrous structure and in imparting an excellent combination of physico-chemical and boron retention properties. A complete boron removal was achieved in 100 mg/l boron solution adsorbent with a dosage of 0.6 g at pH 7 in 2 h time. This was accompanied by a promising reusability suitable for boron removal from solutions. 相似文献
13.
Two different electrospinning processes (traditional single fluid one and a modified coaxial electrospinning with organic
solvent as sheath fluid) are investigated in relation to their capability of producing thinner nanofibers. Both the modified
coaxial electrospinning and single fluid electrospinning can produce thinner nanofibers with polyvinylpyrrolidone (PVP) as
a polymer model and using a poor volatile solvent N, N-dimethylacetamide (DMAc) in different ways. However the traditional
single fluid process was less effective compared to the modified coaxial process, as it suffered more from the limitation
of polymer chain entanglement threshold for maintaining structural uniformity of nanofibers. Using DMAc as sheath fluid in
the modified process facilitated formation of thinner nanofibers without sacrificing their quality. The mechanism should be
that an appropriate DMAc surrounding to the core polymer jet helps to retain it in a fluid state to experience a longer time
electrical drawing, with little adverse influence on the polymer chain entanglements. Nanofiber diameters could also be tailored
in a linear manner using the modified coaxial process simply through manipulating the sheath solvent flow rates. The modified
coaxial process described here extends the capability of electrospinning process and opens a new way to obtain thinner nanofibers
with fine structural uniformity. 相似文献
14.
Nika Veronovski Andreja Rudolf Majda Sfiligoj Smole Tatjana Kreže Jelka Geršak 《Fibers and Polymers》2009,10(4):551-556
Self-cleaning surfaces based on photocatalysis are an extremely promising nano-technological field of extensive research and
development. Recently comprehensive research work has been performed to evaluate the optical, photocatalytic and antimicrobial
properties of TiO2 nano-particles and composites thereof. The aim of this study was to obtain self-cleaning properties for regenerate cellulose
surfaces by nano-modification, using TiO2 nano-coating and to define the impact of the modification on fabrics end-use properties. Two different modified fabrics with
self-cleaning effect were prepared and analysed, i.e. the modification efficiency was determined. In addition, the influence
of fibre modification on several textile properties was determined. However, a soft handle, good appearance and some other
surface properties accompanied by appropriate mechanical properties represent the basis for a high quality fabric therefore
the influence of the modification procedure on textiles handle was studied. 相似文献
15.
Quan Feng Xueqian Wang Anfang Wei Qufu Wei Dayin Hou Wei Luo Xinhua Liu Zongqian Wang 《Fibers and Polymers》2011,12(8):1025-1029
Ployacrylonitrile (PAN) nanofibers were formed by electrospinning. Amidoxime ployacrylonitrile (AOPAN) nanofibers were prepared
by reaction with hydroxylamine hydrochloride, which were used as the matrix for metal ions chelation. FTIR spectra of the
PAN nanofibers and AOPAN nanofibers were recorded for analysis of the surface chemical structures. The AOPAN conventional
fibers were also prepared for comparison, and surface morphologies of the modified PAN conventional fibers and PAN nanofibers
were observed by FESEM. Metal ions concentrations were calculated by AAS. The chelated isothermal process and kinetics parameters
of the modified PAN nanofibers and PAN conventional fibers were studied in this work. Results indicated that the saturated
coordinate capacity of AOPAN nanofibers to Cu2+, Cd2+ was 3.4482 and 4.5408 mmol/g (dry fiber) respectively, nearly two times higher than that of AOPAN conventional fibers. Besides,
the desorption rate of Cu2+ and Cd2+ from metal chelated AOPAN nanofibers was 87 and 92 % respectively in 1 mol/l nitric acid solution for 60 min. The isothermal
processes were found to be in conformity with Langmuir model. 相似文献
16.
Navid Amini Saeedeh Mazinani Seyed-Omid Ranaei-Siadat Mohammadreza Kalaee Kaveh Niknam Vida Adlfar 《Fibers and Polymers》2012,13(8):994-998
Nanofibers have a great potential for enzyme immobilization application due to their large surface area to volume ratio besides their porous structure. In this work, we produce polymethyl methacrylate (PMMA) nanofibers via electrospinning method in dimethylformamide (DMF) as solvent. Thereafter, we employ a chemical method on final PMMA nanofiberous web to covalently immobilize acetylcholinesterase (AChE) enzyme on membrane surface. Morphology and tensile properties of nanofibers are studied as first steps of characterization to make sure of obtaining a properly stable membrane for enzyme carrying application. Thereafter, the stability and activity of immobilized enzymes as two main characteristic parameters are tested and reported for different applications such as biosensor manufacturing. 相似文献
17.
M. Raffi Zaira Batool Mashkoor Ahmad M. Zakria Rana I. Shakoor Muhammad Aslam Mirza Arshad Mahmood 《Fibers and Polymers》2018,19(9):1930-1939
Titanium dioxide (TiO2) is one of the excellent photocatalysts used for degradation of environmetal pollutants. In this work, 2.5, 5.0 and 7.5 wt.% of silver (Ag)-loaded TiO2 nanofibers of mean size 52–134 nm were synthesized by electrospinning method. These electrospun nanofibers were calcined at 500 °C to enable the transformation of Rutile (R) phase to Anatase (A), elimination of reaction moieties from the TiO2 matrix and subsequently formation of Ag clusters. The effect of Ag loading on the morphology, crystal structure, phase transformation, and band gap of these electrospun nanofibers have been characterized by scannining electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), raman spectroscopy and UV-visible spectroscopy. These nanofibers exhibited a red-shift in the absorbance edge and a significant enhancement of light absorption in the wavelength range of 250–550 nm. These electrospun nanofibers were investigated for photodecomposition of methylene blue (MB), and photocatalytic decolorization rates were determined by pseudo-first-order equation. The rate constants for the pure and those of 2.5, 5.0, and 7.5 wt% Agloaded TiO2 nanofibers were computed to be 0.1439 min-1, 0.1608 min-1, 0.1876 min-1, and 0.2251 min-1 respectively. 相似文献
18.
Liping Liang Mengyao Su Cong Zheng Jiaqi Li Haihua Zhan Xuming Li Xu Meng 《Fibers and Polymers》2017,18(12):2307-2314
A straightforward approach was proposed to modify cotton fabric for oil/water separation based on musselinspired reaction. The poly(DMA-Octadecyl acrylate) was designed to contain key chemical constituents present in mussel adhesive proteins by free radical polymerization of dopamine hydrochloride and octadecyl acrylate, which strongly adsorbed to fabric substrates, providing a special surface for fabric. The chemical structure, surface topography, and surface wettability of the fabric were characterized. The results showed that as-prepared cotton fabric displayed a high CA of >150° when dripped water droplets were on the modified fabric surface, and the oil contact angle (OCA) was close to 0°, it had excellent potential to be used in practical applications and has created a new method of fabric modification for oil/water separation. 相似文献
19.
Graft modification of collagen with acrylonitrile in concentrated aqueous solution of sodium thiocyanate (NaSCN) is developed
in this paper. This modification can largely change it’s solubility in water and can be applied in fiber production. Grafting
modified collagen is characterized by infrared spectrum and wide angle X-ray diffraction. Wet spinning of PAN fibers containing
several content of modified collagen is performed. The tests about these fibers show that breaking strength and sonic orientation
decrease as the amount of collagen is raised. The addition of collagen can largely improve the moisture regain of PAN fiber.
Micro-appearance of fibers observed under scanning electron microscope (SEM) presents circular cross section and longitudinal
grooves on surface, the depth of grooves increases with the increasing draw ratio. 相似文献
20.
Seyedeh Nooshin Banitaba Golchehr Amini Ali Akbar Gharehaghaji Ali Asghar Asgharian Jeddi 《Fibers and Polymers》2017,18(12):2342-2348
This study aims to develop a new approach for fabricating hollow nanofibrous yarns by engineering a triple-layer structure (polyvinyl alcohol (PVA) multifilament core surrounded by a layer of PVA nanofibers and a polylactic acid (PLA) nanofiber outer layer). After fabrication of this 3-layer structure, the core portion was extracted, leaving the outer layer intact after dissolving the PVA nanofibers in water. To determine the optimum thickness of the outer layer, hollow nanofiber yarns with five different thicknesses were produced. A hollow nanofiber yarn was also produced using a common method to enable comparison of the methods. In the common method, a core sheath yarn consisting of a PVA multifilament core and a PLA nanofiber outer layer was fabricated, and a hollow yarn was produced by placing the core yarn in hot water. The results revealed facilitation of core extraction from the yarn body of the new 3-layer structure, which occurred due to rapid dissolution of the middle layer. The wicking behavior in the hollow yarn fabricated using the novel method followed the Locus Washburn equation and that of the hollow yarn produced from the core sheath yarn deviated from it. The results demonstrated that tensile properties of hollow nanofiber yarns were improved by increasing the thickness. Furthermore, hemolysis and cytotoxicity assays indicated that the fabricated hollow nanofibrous structure is non-toxic and blood compatible, indicating its potential for use in biomedical applications such as vascular scaffolds. 相似文献