Stabilized nanosilver loaded nylon knitted fabric using BTCA without yellowing

In this study, silver nanoparticles stabilized on the nylon knitted fabric by padding process using 1,2,3,4-butanetetracarboxylic acid (BTCA) and sodium hypophosphite (SHP) without considerable yellowing. This cross-linking combination also dimensionally stabilized the nylon knitted fabric. The SEM images showed the distribution and size of nanosilver within 34 nm. Also, the presence of nanosilver on the fabrics confirmed by EDX and XRD spectrums. The antimicrobial test performed on the treated fabrics against Staphylococcus aureus as a Gram positive and Escherichia coli as a Gram negative bacterium using pour plate test method. A bacterium growth decrease above 96% achieved with 200 ppm nanosilver/BTCA/SHP with standing up to 20 successive rinses. The L*a*b* values had little changes upon increasing the concentration of silver nanoparticles. However the color changes were negligible and the fabric was still white. Moreover, diffuse reflectance spectroscopy, dimensional stability, and water droplet adsorption time as well as statistical analysis of the results investigated and reported.     

Synthesizing and stabilizing silver nanoparticles on polyamide fabric using silver-ammonia/PVP/UVC

A colloidal dispersion of silver nanoparticles were prepared with Tollens’ reagent [Ag(NH₃)₂]⁺ and polyvinyl pyrrolidone (PVP) as a reducing/stabilizing agent trough UVC irradiation and then applied on the nylon fabric by using a simple pad method. The ultraviolet irradiation was assisted to reduce Ag⁺ to Ag⁰. The presence of nanosilver in the solution and on the fabric was confirmed by UV–vis, EDX, SEM and XRD. In addition, the role of PVP as a stabilizing agent on the nylon surface was investigated. Further, an antibacterial test was carried out on the fabrics in the presence of two bacteria namely Staphylococcus aureus and Escherichia coli. The treated fabric with 200 ppm of the above mentioned solution was reduced the bacteria up to 99.2% after 20 washes. Some other properties of the fabric such as color variations, dimensional stability, water droplet adsorption and reflectance spectrum were also carried out and the results thoroughly discussed.     

Effect of laser CO2 irradiation on various properties of polyester fabric: Focus on dyeing

In this research, the effect of CO₂ laser on various properties of polyester fabric specially dyeing was studied. Three disperse dyes of red, yellow, and blue were used and irradiation was performed before and after dyeing. To evaluate the color changes due to laser treatment, CIELAB ΔE color difference values were calculated. The morphology of the irradiated surfaces was examined by scanning electron microscopy. Other properties including color fastness, bending rigidity, wettability, and crystal size were also examined. The results revealed that laser treatment had an increasing effect on the color difference value. Among the three laser parameters examined in this work, laser power had the strongest effect. While no significant color fastness improvement with low laser intensity was observed, high‐intensity laser irradiation increased the light and rubbing fastness. Properties such as wettability and bending rigidity were negatively affected by an increase in laser intensity. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Single-step route to diamond-nanotube composite

Candle wax was used as a precursor for the production of a diamond-nanotube composite in a single step. The composite films were fabricated by sulfur-assisted hot-filament chemical vapor deposition technique. The morphology of the composite films was analyzed by scanning electron microscopy and transmission electron microscopy. Raman spectra of the films show characteristic diamond band at 1,332 cm⁻¹, D-band around 1,342 cm⁻¹, and graphitic G-band around 1,582 cm⁻¹. The electron energy-loss spectroscopy recorded at the carbon K-edge region shows signature features of diamond and carbon nanotube in the fabricated material. The ability to synthesize diamond-nanotube composites at relatively low temperatures by a single-step process opens up new possibilities for the fabrication of nanoelectronic devices.     

Catalysis using gold nanoparticles decorated on nanocrystalline cellulose

A novel nanocomposite was prepared by deposition of carbonate-stabilized Au nanoparticles (AuNPs) onto the surface of poly(diallyldimethyl ammonium chloride) (PDDA)-coated carboxylated nanocrystalline cellulose (NCC). The hybrid material possessed AuNPs (1.45% by weight) with an average diameter of 2.95 ± 0.06 nm. The catalytic activity of AuNP/PDDA/NCC for reducing 4-nitrophenol to 4-aminophenol was compared to other Au-supported composites. An activation energy of 69.2 kJ mol(-1) was obtained for the reaction. Indeed, the reaction rate constant k of (5.1 ± 0.2) × 10(-3) s(-1) was comparable to the benchmark literature value obtained using AuNPs (<5 nm in diameter) decorated on a network of crystalline cellulose fibers. Our strategy promotes the use of natural resources to prepare reusable hybrid inorganic-organic materials for important reactions with facilitated product isolation/purification.     

The effect of functionalized group concentration on the stability and thermal conductivity of carbon nanotube fluid as heat transfer media

In this research, the pristine CNTs sample synthesized by the CCVD method contains catalytic particles and the carbonaceous impurities, and then the special purification procedure was done. By different methods CNT functionalized with various concentration of COOH was prepared. The carboxylated CNTs were analyzed by back titration method for determining the COOH concentrations on the surface of the oxidized CNTs. Thermal conductivity of difference carbon nanotube fluid has been measured under the stable condition by KD₂ prob. For the first time, we have compared the effect of difference COOH concentration as important parameter in stability and heat transfer behavior of nanofluid. The results show that increasing the functionalized group causes better stability and higher thermal conductivity if the surface of MWNT does not damage in functionalize process.     

Characterization of Diamond: Like Carbon Films Synthesized by DC-Plasma Enhanced Chemical Vapor Deposition

In this paper, diamond-like carbons were produced on tungsten and aluminum substrates by DC plasma enhanced chemical vapor deposition (DC-PECVD) system in a C₂H₂/H₂ gas mixture using C₂H₂ as source hydrocarbon and H₂ as etching and diluting gas. The operation pressure during the growth and substrates temperature were 15 Torr and 180°C, respectively. Characterization of the DLCs deposited on tungsten and aluminum substrates were carried out by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), Raman spectroscopy and Atomic force microscopy (AFM). AFM analysis displayed that the DLCs grown on W substrate has lower roughness than the DLCs deposited on Al substrate and it was smoother. FTIR analysis indicates the existence of C–H vibration mode in the DLCs grown on both of substrates. The Raman spectroscopy shows G peak position and I(D)/I (G) ratio decreased for the DLCs grown on W substrate. The SEM images show diffuse and dense distribution of DLCs in Al and W substrate, respectively. These results shows that the optimum conditions were obtained on W substrate.     

Proposal for enhancing the transmission efficiency of photonic crystal 60° waveguide bends by means of optofluidic infiltration

We are proposing a procedure to enhance the transmission efficiency of 60° photonic crystal (PhC) waveguide bends by means of selective optofluidic infiltration of an air hole, which is created as a point defect at the center of the conventional 60° PhC bend. Numerical studies demonstrate that by varying the defect radius and indices of optical fluids, one may enhance the bend transmission level and tune its 3 dB bandwidth over a substantial range of 88-138 nm. In order to perform the numerical simulations, we have used two-dimensional (2D) finite difference time domain plane wave method, keeping in mind that the spectral features obtained by these 2D calculations are about 15% redshifted from those of real three-dimensional structures.     

Preparation and characterization of indium zinc oxide thin films by electron beam evaporation technique

In this work, the preparation of In₂O₃-ZnO thin films by electron beam evaporation technique on glass substrates is reported. Optical and electrical properties of these films were investigated. The effect of dopant amount and annealing temperature on the optical and electrical properties of In₂O₃-ZnO thin films was also studied. Different amount of ZnO was used as dopant and the films were annealed at different temperature. The results showed that the most crystalline, transparent and uniform films with lowest resistivity were obtained using 25 wt% of ZnO annealed at 500 °C.