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1.
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   

2.
Synthesis of biocompatible polymer nanofibers is valuable, due to their use as a cover for burns and as a replacement for bandage because of their antimicrobial properties. In this study, electrospinning of chitosan(Ch) and nanofibers synthesis with antibacterial properties was investigated. Nanofibers with antibacterial properties were synthesized by electrospun of Ch/poly(L-lactide)(PLA)/Imipenem(Imi) polymer solution. The results showed that the optimized ratio of Ch/PLA polymer solution was ratio of 50:50 and Ch 2 wt% and PLA 10 wt% polymer solution was the best weight percentage for nanofiber preparation. Also, the average diameter of Ch/PLA/Imi nanofibers was 143 nm and measured with ImageJ software. Afterwards, the antibacterial properties of Imi as additives (with different percentages) was studied in the polymer solution. The scanning electron microscopy (SEM) images and antibacterial tests were showed that the electrospun of Ch/PLA/Imi polymeric nanofibers were effective against Gram negative bacteria Escherichia coli (E. coli) and inhibited growth of E. coli. The growth and viability percentage of fibroblast cells with nanofibers in αMEM culture are at desirable levels after 6 days.  相似文献   

3.
The synthesis of titanium dioxide nanofibers with 200–300 nm diameter was presented. The new inorganic-organic hybrid nanofibers were prepared by sol-gel processing and electrospinning technique using a viscous solution of titanium isopropoxide (TiP)/poly(vinyl acetate) (PVAc). Pure titanium dioxide nanofibers were obtained by high temperature calcination of the inorganic-organic composite fibers. SEM, FT-IR, and WAXD techniques were employed to characterize these nanofibers. The titanium dioxide nanostructured fibers have rougher surface and smaller diameter compare with PVAc/TiP composite nanofibers. The anatase to rutile phase transformation occurred when the calcination temperature was increased from 600 °C to 1000 °C.  相似文献   

4.
In this paper, curcumin-loaded electrospinning Poly(lactic acid) (PLA) composite membranes were prepared. Curcumin with different contents (1, 3, and 5 wt%) was loaded to study its anticoagulation property as a drug-eluting stent. The structure of the composite membrane was analyzed by Fourier Transform Infrared (FTIR) spectroscopy, and the results suggested that both PLA and curcumin were present in the composite membrane without chemical reaction between them. Scanning electron microscopy (SEM) and related analysis revealed that the average diameters of composite nanofibers were between 756 and 971 nm with better uniformity in the range of the experiment, furthermore the average diameters of composite nanofibers decreased with the curcumin content increase; The in vitro anticoagulation behavior of curcumin-eluting stents was investigated through static platelet adhesion test, revealing that the anticoagulation property of composite membranes was superior to the pure PLA membrane, and the anticoagulation behavior significantly improved with increasing curcumin by dint of SEM observation.  相似文献   

5.
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   

6.
Boron doped PVA/Zr-Al acetate nanofibers were prepared by electrospinning using PVA as a precursor. The effect of calcination temperature on morphology and crystal structure was investigated at 250, 500, and 800 °C. The study also establishes the effect of boron doping on the morphology of PVA/Zr-Al acetate nanofibers at various calcination temperatures. The measurements showed that the conductivity, pH, viscosity and the surface tension of the hybrid polymer solutions have increased with boron doping. In addition, the fibers were characterized by FTIR, DSC, XPS, XRD and SEM techniques. The addition of boron did not only increase the thermal stability of the fibers, but also increased the average fiber diameters, which gave stronger fibers. The DSC results indicated that the melting temperature (Tm) of the fibers was increased from 256 to 270 °C with the addition of boron. XRD peak patterns showed that after further heat treatment at 800 °C, zirconia exists in two phases of tetragonal and monoclinic modifications. Moreover, alumina does not transform into the γ-Al2O3 and θ-Al2O3 phase at 800 °C. The SEM appearance of the fibers showed that the addition of boron resulted in the formation of crosslinked bright surfaced fibers.  相似文献   

7.
The main objective of this work was chemically bioactivation of the conducting polyanizidine (PANIZ) by incorporating a polyester such as polycaprolactone (PCL). Modified PANIZ nanocomposites were synthesized through ring opening and chemical oxidation polymerizations. A four-point probe was applied to measure the conductivity of newly synthesized star-like block copolymer (S-PCL-PANIZ) nanocomposite, which was about 0.44 S cm-1. Conductive biodegradable nanofibers were prepared by electrospinning with 25 and 75 % (wt/wt) S-PCL-PANIZ to PCL. The contact angle of each prepared nanofiber was 87±3°, supporting their usefulness for cell culture. The cultured mouse osteoblast MG63 cells demonstrated normal morphology and significantly higher adhesion and spreading on the nanofiber. The bioactivated PANIZ based nanocomposite may be fruitful in tissue engineering to fabricate conducting biodegradable scaffolds with improved cell adhesion properties for various cell cultures.  相似文献   

8.
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   

9.
The DM production from INRA 200, an early maturing hybrid maize grown for silage, was 10±6 and 14 5 t/ha in mid-October 1972 and 1973 (4±2 and 5±8 tons/ac). The plant population in both years was approximately 112,000/ha (45,320/ac). Whole-crop and cob DM percentages were 18±2 and 21±3 for 1972 and 39±9 and 53±0 for 1973, respectively. The cob yields were 49 and 10±4 t/ha (2±0 and 4±1 tons/ac) in 1972 and 1973 and cob in the two years accounted for 46 and 72% of total yield. At harvest the 1973 crop was 4–6 weeks more mature than the 1972 crop. These differences were attributed to the difference in accumulated temperature recorded from May till October, which was 567°C days in 1972 and 817 in 1973. Whole-crop DM content, yield of cob and yield of cob as a percentage of total yield were studied against seasonal temperature accumulation. In the case of DM percentage there was a highly significant linear regression which showed that 627°C days were needed to mature maize to 24% DM content.  相似文献   

10.
Nanospider technology as a modified electrospinning technique was used for the fabrication of electrospun nanofibers based on poly(vinyl alcohol) (PVA)/poly(ethylene oxide) (PEO) blend as drug delivery system (DDS) for metronidazole (MTZ) as an antimicrobial drug. Electrospun PVA/PEO/MTZ composite nanofibers were stabilized against disintegration in water by heating in oven at 110°C, or by soaking in isopropyl alcohol for 6 hrs. Incorporation of MTZ into electrospun nanofibers was confirmed by SEM, FT-IR spectra and TGA. The drug release results showed that the burst release was suppressed with stabilized electrospun nanofibers compared with non-stabilized ones. Electrospun PVA/PEO/MTZ composite nanofibers exhibited remarkable antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, Aspergillus niger, Penicillium notatum and Aspergillus flavus which varies with the species of the tested organisms.  相似文献   

11.
Carbon nanofiber (CNF)/polyvinylidene fluoride-hexafluoro propylene (PVDF-HFP) composite film was prepared by solution casting and melt pressing. The resultant 2 % CNF/PVDF-HFP composite films were uniaxially drawn at 50 °C, 75 °C, and 100 °C, respectively. In the SEM images, the morphology of drawn CNF/PVDF-HFP composite film confirmed the orientation of the CNF and the polymer matrix. The WAXD results showed the coexistence crystal phase of PVDF-HFP. The drawn CNF/PVDF-HFP composite film demonstrates improved electrical properties. The DSC thermogram results indicated no change in the melting temperature but slightly increased crystallinity with increasing drawing temperature. Dynamic mechanical analysis and tensile test showed an improvement in the storage modulus and stress at a drawing temperature of 75 °C.  相似文献   

12.
The four binary fatty acid eutectics of capric-lauric acid (CA-LA), capric-myristic acid (CA-MA), capric-palmitic acid (CA-PA), and capric-stearic acid (CA-SA) were firstly prepared as solid-liquid phase change materials (PCMs); then, the composite phase change nanofibers consisting of CA-based binary fatty acid eutectic and polyethylene terephthalate (PET) were fabricated by electrospinning for thermal energy storage. The maximum mass ratios of fatty acid eutectics versus PET in the nanofibers could reach up to 2/1. The FE-SEM images revealed that the composite nanofibers possessed smooth and cylindrical morphological structure having diameters of about 100–300 nm. The fatty acid eutectic could be uniformly distributed in the three-dimension network structure of the PET nanofibers. The FT-IR results indicated that the fatty acid eutectic and PET had no chemical reaction and exhibited good compatibility with each other. The DSC measurements showed that the prepared composite nanofibers had appropriate phase transition temperatures (about 5–38 °C) based upon climatic requirement, whilst the phase change temperatures and the enthalpy values of the composite nanofibers could be adjusted by changing the contents and the types of binary fatty acid eutectics in the nanofibers. The TGA results suggested that the onset thermal degradation temperatures and charred residues at 700 °C of the composite nanofibers were lower than those of pure PET nanofibers, but higher than those of fatty acid eutectic, which were caused by the fact that the PET had better thermal stability than fatty acid eutectic.  相似文献   

13.
This paper reports the fabrication, characterization and simulation of electrospun polyacrylonitrile (PAN) nanofibers into pre-impregnated (prepreg) carbon fiber composites for different industrial applications. The electrospun PAN nanofibers were stabilized in air at 270 °C for one hour and then carbonized at 950 °C in an inert atmosphere (argon) for another hour before placing on the prepreg composites as top layers. The prepreg carbon fibers and carbonized PAN nanofibers were cured together following the prepreg composite curing cycles. Energy dispersive X-ray spectroscopy (EDX) was carried out to investigate the chemical compositions and elemental distribution of the carbonized PAN nanofibers. The EDX results revealed that the carbon weight % of approximately 66 (atomic % 72) was achieved in the PAN-derived carbon nanofibers along with nitrogen and lower amounts of nickel, oxygen and other impurities. Thermomechanical analysis (TMA) exhibited the glass transition regions in the prepreg nanocomposites and the significant dependence of coefficient of thermal expansion on the fiber directions. The highest value of coefficient of thermal expansion was observed in the temperature range of 118-139 °C (7.5×10-8 1/°C) for 0 degree nanocomposite scheme. The highest value of coefficient of thermal expansion was observed in the temperature range of 50-80 °C (37.5×10-6 1/°C) for 90 degree nanocomposite scheme. The test results were simulated using ANSYS software. The test results may be useful for the development of structural health monitoring of various composite materials for aircraft and wind turbine applications.  相似文献   

14.
Blended nanofiber webs of poly(L-lactic acid) (PLLA)/poly(L-lysine) (PLys) with a PLys content of up to 3 % were prepared using an electro-spinning process with trifluoroacetic acid as the spinning solvent, and employed as a substrate for silicification. Silica formation on the surface of the PLLA/PLys nanofibers was carried out by immersing the nanofiber webs in silicic acid solutions at various concentrations for different times. The effects of the silicification conditions and PLys content on silicification were examined by scanning electron microscopy, FT-IR, energy dispersive spectroscopy, and the increase in weight of the substrates. Although the amount of silica formed on the PLLA nanofibers increased with increasing silicification time and silicic acid concentration, the uniformity of the coated layer was not controlled. However, the incorporation of small amounts of PLys in the PLLA nanofibers increased the amount and uniformity of the silica formed on the nanofibers.  相似文献   

15.
Fluffy Poly(ortho-phenylenediamine) (PoPD) microspheres with an average diameter of 2 μm have been successfully self-assembled from PoPD nanospheres. The SEM images showed that their surfaces consist of highly oriented nanofibers. The molecular structure of the synthesized fluffy microspheres was characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared (FTIR) and UV-vis spectra techniques. To investigate the self-assembly mechanism of PoPD fluffy microspheres, the effect of mediates and time on the morphology of the products was also studied. The morphological evolution process indicated that the fluffy microspheres originated from PoPD nanospheres, then nanofibers were grew on the surface. The strategy was facile, effective, and controllable for the self-assembly of conducting polymer micro/nanostructures.  相似文献   

16.
Untreated polyethylene terephthalate has limitation in some medical applications, such as wound dressing due to the hydrophobic property. Thereby, Tragacanth Gum (TG) as a natural polysaccharide utilized in polymer solution led to novel semi-bionanofibers of PET/TG blends (15:1, 15:2 and 15:3) through electrospinning method. Fourier transform infrared spectroscopy results confirmed the existence of hydrophilic groups of TG such as hydroxyl groups. Moreover, twice water uptake of PET/TG comparing with PET nanofibers indicated the hydrogel properties, also PET/TG nanofibers possessed high surface wettability through reduction of contact angle from 113 to 0°. Further, differential scanning calorimetry analysis indicated the alteration in the crystalline structure of PET/TG nanofibers that led to faster degradation in various pH values. The SEM images of PET/TG nanofibers displayed the greater average diameter with increasing TG content (283 nm) comparing with PET nanofibers (193 nm). Also introducing more TG in the nanofibers exhibited lower mechanical properties.  相似文献   

17.
We report our study on fabrication of soluble eggshell membrane (SESM) and silk fibroin (SF) nanofibers composite (SF/SESM) for facemasks by electrospinning. Biocompatibility of the SF and SESM, determined from hydrophilicity results, is exploited in SF/SESM nanocomposite for facemask application. The SF/SESM nanocomposites were prepared in different ratios of SF and SESM. The samples were characterized by scanning electron microscopy (SEM), FTIR and water droplet adsorption tests conducted via water contact angle (WCA) and water droplet diffusion. The results revealed that addition of SESM has insignificant effect on the electrospinnability of SF nanofibers in the studied ratios. The SEM results depicted regular morphology of the nanofibers except increase in nanofiber diameter with addition of SESM. The FTIR results confirmed respective peaks of SF and SESM in SF/SESM nanocomposite. WCA of the nanofibers decreased with addition of SESM such that for SF/SESM30, 30 % SESM, it reduced to 0 ° from 101 ° for pure SF nanofibers. The research results demonstrate SF/SESM30 nanocomposite as optimum ratio of SF and SESM for facemasks and other biomedical applications.  相似文献   

18.
Microcrystalline cellulose (MCC) isolated from cheap, fast-growing and abundant accessible Sacred Bali bamboo (Schizostachyum brachycladum) was utilized as reinforcement material in the seaweed-based composite film. Isolation of MCC was carried out by using a combination of pulping, bleaching and acid hydrolysis process. This study emphasized on the feasibility of MCC production from Sacred Bali bamboo by studying its properties using X-ray diffraction (XRD), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The commercial-MCC (CMCC) was used as reference material. Results showed that the production yield, moisture content (MC) and fiber length of bamboo-MCC (BMCC) were 83.37±1.48 %, 4.50±0.5 %, and 0.47±0.02 mm, respectively. According to the chemical analysis by FTIR, both lignin and hemicellulose were completely removed from BMCC, and thus, improved the crystallinity (78 %) and thermal stability (≈325 °C) of BMCC. This study also revealed that MCC produced from Sacred Bali bamboo demonstrated strong mechanical reinforcement effect in the seaweed-based film. Hence, Sacred Bali bamboo-MCC could be used as reinforcement material in the polymer.  相似文献   

19.
The Fe-montmorillonite (Fe-MMT) combined catalysis effects of Fe ion with barrier effects of silicate clays, was firstly synthesized by hydrothermal method, and then was modified by cetyltrimethyl ammonium bromide (CTAB). The organic-modified Fe-montmorillonite (Fe-OMT) was dispersed in the N, N-dimethyl formamide (DMF) and then compounded with polyacrylonitrile (PAN) solution which was dissolved in DMF. The composite solutions were electrospun to form PAN/Fe-OMT nanocomposite fibers. The influences of the Fe-OMT on the structure, morphology, thermal, flammability and mechanical properties of PAN nanocomposite fibers were respectively characterized by X-ray diffraction (XRD), High-resolution transmission electron microscopy (HRTEM), Scanning electron microscopy (SEM), Thermogravimetric analyses (TGA), Micro Combustion Calorimeter (MCC) and Electronic Single Yarn Strength Tester. It was found from XRD curves that there was not observable diffraction peak of silicate clay, indicating that the silicate clay layers were well dispersed within the PAN nanofibers. The HRTEM image indicated that the multilayer stacks of nanoclays could be found within the nanofibers and were aligned almost along the axis of the nanofibers. The SEM images showed that the diameters of nanocomposite fibers were decreased with the loading of the Fe-OMT. The TGA analyses revealed that the onset temperature of thermal degradation and charred residue at 700°C of PAN nanocomposite fibers were notably increased compared with the pure PAN nanofibers, contributing to the improved thermal stability properties. It was also observed from MCC analyses that the decreased peak of heat release rate (PHRR) of the PAN nanocomposite fibers reduced the flammability properties. The loadings of Fe-OMT increased the tensile strength of PAN nanocomposite fibers, but the elongation at break of PAN nanocomposite fibers was lower than that of the PAN nanofibers.  相似文献   

20.
Homo and copolymers of monomers 2-(N-phthalimido) ethylmethacrylate (NPEMA) and 4-Chloro-3-methyl phenyl methacrylate (CMPMA) were prepared in N,N-dimethyl formamide (DMF) solution at 70 °C using 2,2-azobisisobutyronitrile (AIBN) as initiator. The solution of poly(NPEMA-co.-CMPMA) in 20 % DMF was used to fabrication electrospun nanofiber by electrospinning technique. IR data were primarily employed to characterize polymers. The formation of nanofibers was identified by SEM study. The metal ion uptake capacity of copolymers and nanofibers were obtain by batch equilibrium method using different metal ion solution. The antimicrobial activity of the copolymers, Polymer nanocomposites and their nanofibers were tested against different microbial organisms by using quantitative method. The main objective of this investigation was to find whether nanofiber are better remover of metal ions compared to copolymers. It was also aimed to study the efficacy of nanofibers of copolymers and copolymer composite with nano Ag as water sanitizer.  相似文献   

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