نشریه پژوهش های کاربردی مهندسی شیمی - پلیمر
سال دوم شماره 2 (پیاپی 4، تابستان 1397)

In this study, the effects of drying temperature and mechanical pressure on the surface structure and dynamical properties of polyaniline (PAni) were studied. PAni was synthesized through the aniline polymerization process in the presence of ammonium persulfate in acidic medium and normal methyl-2-pyrrolidine solution. The obtained solution was dipped on a substrate of quartz glass. Atomic force microscopy (AFM) analysis based on nano-indentation tests were used to determine the values of hardness, Young’s modulus and Poisson’s ratio of the films. The results of the analysis of the scanning electron microscope demonstrated that the surface morphology of the film is changed from a fiber-to-interconnected cross-linked networkby increasing the drying temperature. The transmission electron microscope analysis showed that the diameter of the fibers on the surfaces dried at 318 K and 418 K was 18 and 30 nm, respectively. AFM results showed that the mean surface roughness of PAni film at 318 K without mechanical pressure was 63 nm, while for the film pressed at 5 MPa was less than 35 nm. Thermo-mechanical analysis showed that the glass transition temperature of the PAni film prepared without mechanical pressure and the film pressed at 5 MPa were 386 K and 378 K, respectively. Investigating the temperature dependence and applied pressure on the film surface in determining the viscoelastic properties of the PAni nanostructured film can provide readers with appropriate information about the storage and loss modulus of the film and the activation energy of the polymer layer during the thermal decomposition process.

Fiber production in nanoscale prepares high surface contact for fibers and leads to the improvement of their properties with respect to other fibers. A convenient and effective method for nanofiber production with different diameters is electrospinning. Various effective parameters on electrospinning processes, including environmental, equipment, and solution variables can produce fibers with different morphologies. PVA has been used in various fields of applied research because of its high thermal stability, biocompatibility, non-toxic and solubility in water. The published reports indicated that properties of the PVA are improved with the addition of bentonite. In this research, to prepare PVA/nano-bentonite nanofiber membrane, the optimum amounts of three effective variables on the above-mentioned processes were determined. According to the obtained results, the voltage of 11 kV, the feeding rate of 0.5 mL/h and bentonite concentration of 3% w/w were optimum conditions for the process of PVA/nano-bentonite nanofiber composite production. In this condition, the average diameter of produced nanofibers was 243 nm with the standard deviation of 0.0551 and the tensile strength of 7.64 MPa. The results showed that the addition of bentonite to PVA increase intensity of nanofibers and decrease the diameter of nanofibers from 308 nm to 243nm.Therfore, the produced PVA/bentonite nanofiber composite is a good membrane for water treatment.

Methyl Tert-butyl Ether(MTBE) has been used as a booster in gasoline octane numbers in many countries, but after a short time due to the high absorption in water and the possibility of entry into groundwater, its use in developed countries is prohibited. In this work, for the first time, to reduce the adverse environmental effects, MTBE was encapsulated, and release control was considered. For this purpose, the inverse mini-emulsion polymerization of monomer methylmethacrylate(MMA) was performed in the presence of MTBE and in the cyclohexane medium by oil/water/oil. Poly methyl methacrylate/MTBE nanocapsules were synthesized in 0.5, 1, 2 ratios of MTBE to methyl methacrylate (R = MTBE / MMA).
The effect of changing R values ​​on conversion polymerization, on encapsulation efficiency of MTBE and on the morphology of capsules was investigated. For this purpose, TGA and TEM were used. Changing the R ratio from 0.5 to 2 allowed the capsule to be controlled in the range of 50-500 nm. The start of the MTBE degradation range of 130 ° C increased to 250 ° C due to the presence of the MTBE inside the capsule, and it was possible to start controlling the release of the nucleus by heating and starting at a temperature of 250 ° C. By addition of 1.5% of the capsules to the gasoline, the octane number increased by 5 units.
According to the results inverse mini-emulsion polymerization is a suitable method for encapsulating and reducing the environmental effects of MTBE by limiting its contact with the environment.

In recent years, with the advancement of nanoscience, many scientists have used nano materials to solve existing problems in various sectors of oil industry. Nanofluids made with these materials can facilitate the separation of oil and gas in a reservoir and increase oil recovery factor compared to current methods. Therefore, in this work, the effect of clay nanoparticles on oil recovery factor was investigated. For this purpose, two different base fluids, water and ethanol, were used to disperse the nanoparticles. The effect of adding clay nanoparticles on viscosity changes and interfacial surface tension was determined. Also, in order to investigate the effect of nanoparticle concentration in the base fluid on the ultimate oil recovery factor, nanofluids with 3 and 5 wt% were prepared. Results show that oil recovery factor increases significantly in these conditions by adding them into the base fluid, though nanofluids included clay nanoparticles have less stability. Also, the effect of these nanoparticles dispersed in water is greater than in ethanol. For example, at 5 wt%, oil recovery factor for water based nanofluid was 49.7% and for ethanol based nanofluid was 46%.

In this study, three different size (100-300-500 µm) of the rubber powder (waste tire) were used in the formulation of epoxy- phenolic adhesive. Rubber powder was modified with grafting method by acrylamide monomer. In order to prevent any loss in properties such as modulus and strength of the adhesive, which is due to the addition of rubber powder to the adhesive, the micro particles of silica were used in formulation of epoxy- phenolic adhesive.  The experiment was designed by Taguchi method, and in the experiment, the effect of the composition of rubber powder, size of rubber powder, composition of silica filler and phenolic resin on mechanical and thermal properties of epoxy adhesives were investigated. To study the mechanical properties of adhesives and adhesion properties, dumbbell-shaped specimens and single edge lap bonds that have been made of metal (stainless steel) to composite (epoxy resin / carbon fiber) were prepared and subjected to tensile test. Thermal stability and interfacial interaction between epoxy and filler in adhesive formulation were explored by thermogravimetric analysis and Fourier transform infrared spectroscopy analyses, respectively.  Tensile test results showed that for lap- joint bonding with the addition of each factor in its optimal level into epoxy adhesive, strength, modulus and toughness increase by 7.5%, 27.56% and 114% respectively in comparison with  the samples bonded with the neat  epoxy adhesive. A significant increase was obtained in thermal stability for formulated adhesive samples compared with neat epoxy adhesive.

In this research, general performance of Radial basis function (RBF) Artificial neural networks in experimental data on effect of the NiO, WO3, TiO2,ZnO and Fe2O3 nanoparticles in different temperatures and mass fractions on the viscosity of crude oil has been studied. The morphology and stability of the nanoparticles has been analyzed by DLS and TEM analysis, the results showed that the average diameter of the nanoparticles is from 10 to 30 nm which defers for different oxide nanoparticles. The general method for calculating the optimum span of the Isotropic Gaussian function with special algorithm for learning RBF networks, has been presented. This study's results declared that the RBF artificial neural networks, because of having strong academic basis and having the ability to filter the noises, has a good performance. With increase in temperature, the ratio of the viscosity of the nanofluids decreases compering to the viscosity of the basefluid. Also with increase in nanoparticles mass fraction the related viscosity increases boldly. For temperatures higher than 50°C, the related viscosity is less than the viscosity of the basefluid.