فصلنامه مواد پیشرفته و پوشش های نوین
پیاپی 36 (بهار 1400)

In this study, a waterproof hybrid nanofibrous membrane with breathability and high resistance to water penetration was prepared. For this purpose, polyurethane-poly(vinylidene fluoride) hybrid nanofibers with different ratios and with addition of silica nanoparticles were produced by electrospinning method. The effect of different ratios of the studied polymers on the morphology and performance of nanofibrous membranes such as breathability and waterproof properties were studied. Scanning electron microscopy and analysis of air permeability, hydrostatic pressure and water vapor permeability were used for this purpose. Morphological study of hybrid nanofibrous membrane shows the fabrication of uniform and bead-free fibers with average diameter of 60 to 80 nm. Moreover, increasing the ratio of PVDF polymer in nanofibrous membrane by 70% increased their air permeability and hydrostatic pressure. The results also show that the nanofibrous membrane containing 70:30 PVDF/PU, exhibits better breathability and waterproof properties, as its air permeability and water vapor permeability were obtained 68.6 mL/cm2.s and 2853 g/m2/day, respectively.

Nowadays environmental concerns, have shifted various coating industries, including automotive industry, to the use of water-based coatings. Polyesters by creating a double bond in the resin backbone they will be able to obtain the potential of reaction with acrylic monomers to achieve purposeful functionality. They considered as one of the most widely used components in automotive basecoat industry. In this study a polyester resin was produced using adipic acid, cardura E10, trimethylol propane and fumaric acid. It was then grafted with acrylic acid and butyl acrylate monomers to enhance hydrophilicity and water dispersibility. Synthesized resin, after neutralization by triethylamine, can be dispersed in water and form a water-reducible polyester acrylate dispersion. Numerical and weight average molecular weight of this resin were reported by GPC test at 980 and 2069 respectively with a PDI of 2.1. The acid and hydroxyl values of the product were 105 and 205, respectively. The final product’s particle size were measured at 168.1 nm using the DLS method. The stability of the dispersion was confirmed by the zeta potential test with an average value of -88.9 mV. The curing process in accompany with a melamine resin was verified by the cross cut adhesion test which was reported 3B.

Some organic contaminants can enter drinking water without being removed by conventional treatment methods. One group of these contaminants are antibiotics that, if present in water and entering the human body, can cause bacterial resistance over time. Therefore, finding new methods and materials that can remove this group of pollutants from the environment is significant. In the present study, carbon nitride nanolayers were prepared by heat decomposition of dicyanamide and then silver nanoparticles were deposited on the surface of carbon nitride. The photocatalytic properties of the synthesized composites for the degradation of the tetracycline in water were then investigated. The obtained powder was characterized by transmission electron microscopy, X-ray diffraction, surface area test and ultraviolet-visible spectroscopy. The results showed that carbon nitride was successfully synthesized and silver nanoparticles with average size of 30 nm were deposited on the carbon nitride surface. The produced samples showed absorption in the range of visible light (400 to 700 nm). Addition of silver nanoparticles improved the photocatalytic properties of carbon nitride by preventing electron-hole recombination. The sample containing 2 weight percent of silver had the highest photocatalytic properties. The produced composite samples degraded the tetracycline antibiotic in the water up to 89% after 30 min. The reaction rate constant increased from 0.0087 min-1 in the pure carbon nitride sample to 0.036 min-1 after deposition of silver nanoparticles.

Cyanide is a by-product of various industrial chemical processes found in industrial effluents which must be treated before it is discharged into the environment. Industrial effluents containing cyanide is treated through different methods including physical, chemical and biological processes which are often too expensive.The aim of this study is to evaluate the application of Artificial Neural Network (ANN) in predicting the removal efficiency of cyanide ions from aqueous solutions by Zno@MOF-199 nano-adsorbent. The research data was collected based on laboratorial study of important parameters involved in the Levenberg-Marquardt Back-propagation Artificial Neural Network Model (BP-LM) for prediction of cyanide removal efficiency including pH range from 5 to 9, contact time of 30 to 90 minutes and temperature range from 25 to 45 ºC. Parameters such as pH, temperature, contact time, adsorbent weight and sample volume were considered as input and cyanide removal efficiency as output data. In the comparison of different models, statistical criteria of correlation coefficient and sum of squared errors (SSE) were applied. The obtained results, 0.985 for the correlation coefficient and 0.65 for the sum of squared errors, indicate a successful prediction of the network in modeling as well as the efficiency of neural network in predicting the removal efficiency of cyanide ions from the solution.

In recent years, volume of waste water produced by diverse field of industries is one the most vital challenges. To tackle this issue, numerous solutions have been submitted and among them, utilizing Metal- Organic Frameworks (MOFs) has been considerably paid attention as an appropriate option for water treatment due to their unique properties, such as low band gap and high specific surface area. In this study, MIL53 (Fe) was synthesized using nitrite salt source (FeNO3.9H2O) via solvo-thermal method at 120ºC, 150ºC and 180ºC. Subsequently, obtained powders was characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and UV-vis DRS. Eventually, photocatalytic efficiency of prepared samples was analyzed via Methylene Blue (MB) degradation under halogen lamp (500 W). Obtained results showed that the synthesized powder at 180ºC (sample C) had the most percentage of crystallinity and light absorption. Likewise sample (C) was the most efficient sample and possessed the highest band gap and the most rate of dye degradation.

The growth kinetic of amorphous carbon (a-C) thin films was investigated in the relation to the surface morphology and structural transformations. The a-C thin films were deposited by ion beam sputtering technique on the glass substrate. According to Avrami's model, the growth at the thickness above 56 nm (after 900 s deposition) is two-dimensional and the proposed equation for investigating about the growth process of amorphous carbon thin film in the present study is as follows: V=1-exp⁡(-2×〖10〗^(-7) t^2 ). Transformations of the thickness is similar to proposed Avrami's model follow a characteristic s-shaped, or sigmoidal, profile during deposition time from 300s to 4500s, where the transformation rates are low at the beginning and the end of the transformation but rapid in between. Surface roughness and structural transformation depend on the film thickness. Raman spectra showed the maximum displacement in G peak position created in the film thickness equal 360 nm with the reduction of the growth rate. The ID/IG ratio, the size of graphite crystallites with sp2 bonds (La) and the roughness of this layer is equal to 1.2, 1.48 nm and 20.39±4.8 nm, respectively.

Composite particles of carbon black pigment and styrene butyl acrylate copolymer were produced by emulsion polymerization process. The properties of produced toner particles were evaluated using Dynamic Light Scattering test to measure particle size and particle size distribution, Differential Calorimetry and thermal Gravimetry analyzes to investigate thermal behavior, Scanning electron microscopy test to detect microstructure, Gravimetric test to evaluate reaction conversion and Colorimetric test and Light microscope to check color properties and its uniformity. The results show that the produced toner has an average particle size of 0.07 micrometers with a particle size distribution of 1.332, the glass transition temperature is about 70 ° C and the reaction conversion is 97%. According to the thermal behavior of the sample, it can be said that the copolymerization reaction has been performed On the other hand, by comparing the results of spectrophotometric test of the sample produced with the toner samples available in the market, it was observed that the produced sample has similar color properties to the samples available in the market. Most of the properties of the composite particles produced are suitable and efficient for use as toner in electrographic printers.