Preparation and application of glycolysed polyurethane integral skin foams recyclate from automotive wastes

Summary Glycolysis of isocyanate derived foams with glycol and amine mixture is a simple and economically attractive chemical recycling process. A mixture of diethylene glycol (DEG) and diethanol amine (DEA) is used as solvent system and sodium hydroxide as the catalyst. The obtained polyols can be completely reused in the formulation of integral skin foams in blend with virgin polyol.     

Biodegradable polyaniline/dextrin conductive nanocomposites: synthesis,characterization, and study of antioxidant activity and sorption of heavy metal ions

Conductive nanocomposites based on polyaniline/dextrin were synthesized by in situ polymerization of aniline in presence of dextrin. The nanocomposites were characterized by field emission scanning electron microcopy, differential scanning calorimetry, Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, X-ray diffraction and conductivity measurements. It was observed that the conductivity values increased with the increase of aniline content in nanocomposites. The obtained nanocomposites have been analyzed for the antioxidant activities using 2,2-diphenyl-1-picrylhydrazyl assay. The results showed that the antioxidant activity of the nanocomposites was enhanced by increasing the aniline content. Polyaniline/dextrin nanocomposites were used as sorbent materials for the removal of heavy metals from aqueous solutions. The sorption data indicated that the novel polyaniline/dextrin nanocomposites have high tendency for the removal of heavy metal ions such as Cu(II), Cd(II) and Pb(II) from aqueous solutions. In addition, the in vitro biodegradability of polyaniline/dextrin nanocomposites with different weight ratios was studied by soil burial tests. The result demonstrated that the nanocomposites are biodegradable under soil environment by degradation range between 30.18 and 74.52 %. The observed physical properties of the polyaniline/dextrin nanocomposites open interesting possibilities for novel applications of electrically conducting polysaccharide-based composites, particularly those that may exploit the antioxidant activity and heavy metal ions sorption of the polyaniline/dextrin nanocomposites.     

Wind energy status of Iran: Evaluating Iran's technological capability in manufacturing wind turbines

Iran, as a developing country, will be confronted with a significant increase in electricity demand in future years. Being a petroleum producing country has resulted in extreme subsidies for energy production from fossilized resources such as oil and gas. This issue is one of the most important factors regarding underdevelopment of renewable energies in Iran. Expansive use of fossil resources in providing the necessary energy has resulted in Iran being among the 20 countries that have a share in the 75% spread of greenhouse gases. This issue has resulted in greater attention on behalf of the energy sectors policy makers regarding renewable energies, especially wind. Awareness regarding the current condition of each system is the first step for optimum policy making. On this basis, analyzing Iran's wind conditions and assessing its technological capabilities is considered a pre-requisite for the wind sectors policy making. This paper aims at studying Iran's wind energy status in the form of available capacities, power production, wind power plant characteristics, principal agents and existing protective laws. Also, the main focus of this paper is on evaluating Iran's potential and effective technological capabilities for producing the main parts of wind turbines in different sizes. In order to fulfill this task, sector-level technological capabilities are defined. Then by analyzing active organizations in this field, Iran's capability level will be determined and by comparing it with the ideal conditions, Iran's technological gaps will be identified. The reasons for the creation of such shortcomings will also be introduced from different aspects in the form of the Atlas model. Finally, Iran's potential capabilities in resolving technological shortcomings will be identified.     

DME DIRECT SYNTHESIS FROM SYNGAS IN A LARGE-SCALE THREE-PHASE SLURRY BUBBLE COLUMN REACTOR: TRANSIENT MODELING

In this research, a new transient mathematical model based upon tanks-in-series configuration was developed to simulate the direct synthesis of dimethyl ether (DME) from syngas in a commercial-scale slurry bubble column reactor. A comparison between the simulation results and experimental data showed that the applied model might acceptably describe the behavior of the slurry reactor. Furthermore, simulation results in the heterogeneous bubble flow regime indicated that the proposed model with 10 tanks-in-series provided the optimum condition. Utilizing this transient model and considering catalyst deactivation, the effect of operating conditions on DME productivity and CO conversion were investigated. In addition, the dynamic behavior of the reactor was studied after implementing a step change in the reactor's coolant fluid temperature.     

Mercury(II) selective membrane electrode based on 1,3-bis(2-methoxybenzene)triazene

A plasticized poly (vinyl chloride) membrane electrode based on 1,3-bis(2-methoxybenzene)triazene (MBT) for highly selective determination of mercury(II) has been developed. The electrode showed a good Nernstian response (30.2 ± 0.3 mV decade^− 1) over a wide concentration range (1.0 × 10^− 7−1.0 × 10^− 2 mol L^− 1). The limit of detection was 5.0 × 10^− 8 mol L^− 1. The electrode has a response time about 15 s and can be used for at least 1 month without observing any deviation from Nernstain response. The proposed electrode revealed an excellent selectivity toward mercury(II) ion over a wide variety of alkali, alkaline earth, transition, and heavy metal ions and could be used in the pH range 2.6–4.2. The electrode was used in the determination of Hg²⁺ in aqueous samples and as an indicator electrode in potentiometric titration of Hg(II) ions.     

Primary and secondary resonance analysis of FG/lipid nanoplate with considering porosity distribution based on a nonlinear elastic medium

Abstract

In this study, the nonlinear vibration analysis of the new generation nanostructures is investigated. The composite nanoplate is fabricated from the functional-graded (FG) core and two lipid layers on top and bottom of the FG core as face sheets. The nonlinear vibration analysis is studied in the presence of the external harmonic excitation force. The porosity effect on the free and force vibration analysis of the composite nanoplate is investigated. The nonlocal elasticity theory is utilized to obtain the nonlinear differential governing equation. The Kelvin–Voigt model is used to model the viscoelastic effect of the lipid layers. The Hamilton's principle is utilized to obtain the differential governing equation. The Galerkin's method is used to discrete the nonlinear partial differential governing equation to a nonlinear ordinary differential equation. The multiple scale method is used to solve the ordinary differential equation. The numerical results are compared with the reported results in the literature. A comparison between the presented numerical results and the Runge–Kutta results is done and good agreement is obtained. In the presence and absence of the porosity, the system vibration behavior is studied in the primary and secondary resonance cases. The results show that the porosity distribution types play an important role in the mechanical behavior of the composite nanoplate. Also, the numerical results show that the nonlinear frequency of the system decreases by passing time. This study can be useful to product the sensors and devices at the nanoscale with high biocompatibility.     

Investigation on effect of pulse correction on structure property in dissimilar welds of galvanized steel and aluminum alloy obtained by gas metal arc welding cold metal transfer

Gas metal arc welding cold metal transfer (GMAW-CMT) method with AlSi₃Mn filler wire was performed on welding of the 5754 aluminum alloy with thickness of 3 mm to the galvanized steel with thickness of 2 mm aluminum alloy to investigate the effect of pulse correction on structure and mechanical properties of welded samples. In accordance with results, GMAW-CMT provides good tensile performance. It was attributed to the various throat weld size and wetting actions because of the influence of pulse correction on structure of welded joints. It was inferred that on employing +5 pulse correction resulted in better and consistent tensile strength of 209 MPa. Furthermore, the results showed that increasing the pulse correction led to increasing of flow in the filler wire and in fact raising of brazed seam width and throat weld size. In addition, the thickness of intermetallic compound layer which was formed along the interface during the GMAW-CMT was varied by changing of pulse correction. It has been found that by increasing the pulse correction from–5 to +5, the throat weld size increased and consequently led to a change in the tensile strength of the welded joints.     

Artificial neural networks application to predict the ultimate tensile strength of X70 pipeline steels

The paper presents some results of the research connected with the development of new approach based on the artificial neural network (ANN) of predicting the ultimate tensile strength of the API X70 steels after thermomechanical treatment. The independent variables in the model are chemical compositions (carbon equivalent), based upon the International Institute of Welding equation (CE_IIW), the carbon equivalent, based upon the chemical portion of the Ito-Bessyo carbon equivalent equation (CE_Pcm), the sum of the niobium, vanadium and titanium concentrations (VTiNb), the sum of the niobium and vanadium concentrations (NbV), the sum of the chromium, molybdenum, nickel and copper concentrations (CrMoNiCu), Charpy impact energy at ?10 °C (CVN) and yield strength at 0.005 offset (YS). For purpose of constructing these models, 104 different data were gathered from the experimental results. The data used in the ANN model is arranged in a format of seven input parameters that cover the chemical compositions, yield stress and Charpy impact energy, and output parameter which is ultimate tensile strength. In this model, the training, validation and testing results in the ANN have shown strong potential for prediction of relations between chemical compositions and mechanical properties of API X70 steels.