Prediction of tensile modulus of nanocomposites based on polymeric blends

A simple model was proposed for predicting the Young’s modulus of nanocomposites based on polymeric blends. First, a simple model was derived for binary blends containing only two polymers. This model is more useful for those blends with high degree of continuity. Therefore, the morphology of the blend is divided into parallel and series regions and the percolation theory is used to calculate the volume fraction of these phases. In the next step, the addition of nanoclay, as a third component, is being considered. These nanoparticles may possibly find locations at the matrix, minor or interface. In the latter case, the model was expanded into a three-phase model including the matrix, dispersed and a third phase containing nanoclay which itself was split into series and parallel sections. A model related to the reinforcing effect of nanoclay was employed and combined with the above model to estimate the modulus of this ternary nanocomposite. The experimental data which is obtained from nanocomposite based on low-density polyethylene/thermoplastic starch/Cloisite 30B were compared with the model results and revealed a good agreement with each other. Also, the model predictions were compared with other experimental data from literature sources to verify the model accuracy. The comparison showed that the model predictions can predict the experimental data rationally. This model can be used to determine the structure of a nanocomposite without any other expensive tests.     

Minor Components in Canola Oil and Effects of Refining on These Constituents: A Review

Crude canola oil is composed mainly of triacylglycerols but contains considerable amounts of desirable and undesirable minor components. Crude canola oil is refined in order to remove undesirable minor compounds that make this oil unusable in food products. However, refining can also cause the removal of desirable health-promoting minor components from the oil. The first section of this review describes the chemical composition of canola oil, followed by a brief introduction to the effects of minor components on canola oil quality and stability. Following a review of traditional canola oil refining methods, the effects of individual refining stages on the removal of both desirable and undesirable components from canola oil are presented and contrasted with other common vegetable oils.     

Rhodium‐Catalyzed Homogeneous Reductive Amidation of Aldehydes

The catalytic reductive amidation of an aldehyde (hexanal) with an amide (acetamide) is reported. Apart from the desired N‐hexylacetamide, the two isomeric unsaturated intermediates as well as hexanol are produced together with higher mass products that arise from aldol condensation and diamide coupling of the aldehyde. Screening of different catalyst precursor salts, ligands and reaction conditions led to the finding that the catalytic system based on the (cyclooctadiene)rhodium chloride dimer, [Rh(cod)Cl]₂, in combination with the ligand xantphos and an acid co‐catalyst results in high selectivity for the desired product. Under optimized conditions nearly full conversion is reached with high selectivity to the desired N‐alkylamide and with a very high N ‐ alkylamide/alcohol ratio, while producing only small amounts of by‐products. The scope of the reaction has been investigated using different amides as well as aldehydes; the results show the general applicability of this novel reaction, but with electron‐withdrawing amides the selectivity to N‐alkylamide is lower. NMR studies showed that the nucleophilic addition of acetamide to hexanal is acid catalyzed, forming N‐(1‐hydroxyhexyl)acetamide in equilibrium with both hexanal and the dehydrated unsaturated imides. A catalytic mechanism is proposed in which a strong acid such as HOTs acts as a co‐catalyst by establishing a rapid chemical equilibrium between the aldehyde, acetamide and the intermediates. Furthermore, it is proposed that the presence of acid causes a change in catalytic species, enabling a cationic Rh/xantphos hydrogenation catalyst to selectively hydrogenate the intermediates to N‐hexylacetamide in the presence of hexanal.     

Design of a dual function buried channel waveguide for pulse compression and dispersion compensation in two different wavelengths for the purpose of optical integration

Silicon - Optical pulse compression and dispersion compensation are two important applications in optical systems. The present paper proposes a dual function buried channel waveguide to be used in...     

Flow and heat transfer of two immiscible fluids in double-layer optical fiber coating

The coatings of optical fibers are generally characterized by a multi-layer coating structure. In this work, the mathematical modeling of two immiscible non-Newtonian fluids for optical fiber coating inside a straight annular die is developed in the form of a nonlinear differential equation with nonhomogeneous boundary conditions. Two non-Newtonian fluids, namely power law and Phan-Thien–Tanner fluids, are used in the primary and secondary coating dies, respectively. An exact solution is obtained for velocity fields and temperature distributions for the primary and secondary coating resins. The thickness of coated fiber optics is also calculated for both layers. The effect of different emerging parameters on the solution is discussed and sketched.     

Thermodynamic Equilibrium Analysis of Propane Dehydrogenation with Carbon Dioxide and Side Reactions

A thermodynamic analysis of propane dehydrogenation with carbon dioxide was performed using constrained Gibbs free energy minimization method. Different reaction networks corresponding to different catalytic systems, including non-redox and redox oxide catalysts, were simulated. The influences of CO₂/C₃H₈ molar ratio (1–10), temperature (700–1000 K), and pressure (0.5–5 bar) on equilibrium conversion and product composition were studied. In the presence of CO₂ with a molar ratio of CO₂/C₃H₈ = 1, the temperature of dehydrogenation can be 30 K lower than that of dehydrogenation in the presence of steam (H₂O/C₃H₈ = 1) and about 50 K lower than that of simple dehydrogenation without dilution to achieve 60% propane conversion. It was found that the occurrence of dry reforming of propane and coke-forming side reactions could strongly impact the equilibrium product composition of the multireaction system and, therefore, these reactions should be kinetically controlled. Comparison of the simulated reactant conversions with those reported in the literatures revealed that the experimental conversion levels of propane are far below the corresponding equilibrium values due to rapid catalyst deactivation by coke, implying that research efforts should be directed toward formulation of more active and selective catalysts.     

Preparation,characterization, and dynamic adsorption–desorption studies on polypyrrole encapsulated TiO2 nanoparticles

Binary doped polypyrrole (PPy) encapsulated Titania (TiO₂) nanoparticles were prepared by oxidative polymerization using FeCl₃ as oxidant in presence of camphorsulfonic acid (CSA) as surfactant. Both FeCl₃ (oxidant) and camphorsulfonic acid (surfactant) also act as dopant and hence thus prepared polypyrrole/Titania (TiO₂@PPy) is termed as binary doped nanocomposite i.e. FeCl₃ dopes polypyrrole by oxidation mechanism while camphorsulfonic acid dopes polypyrrole by protonic doping mechanism. The TiO₂@PPy coreshell nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD), thermogravimetry, differential scanning calorimetry (DSC), field emission‐scanning electron microscopy (FE‐SEM), and inductance‐capacitance‐resistance (LCR) measurements. The results indicated that the structural and electrical properties of the TiO₂@PPy coreshell nanocomposites were significantly influenced by the extent of TiO₂ nanoparticles loading of polypyrrole. The direct current (DC) electrical conductivity of the as‐prepared TiO₂@PPy coreshell nanocomposites was higher than that of PPy. As‐prepared TiO₂@PPy coreshell nanocomposites were also studied for their dielectric losses for alternating current (AC) which is useful characteristic for their application in the fabrication of charge storing devices. TiO₂@PPy coreshell nanocomposites showed synergistic effect of combining components in improving their alcohol sensing properties. This improvement may be attributed to the adsorption on and desorption from alcohols TiO₂@PPy interface of the nanocomposites and alcohol vapors causing decrease in depletion region. The TiO₂@PPy coreshell nanocomposites were observed to show better reproducibility of electrical conductivity and fast self‐recovery during the alcohol vapor sensing process. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43411.     

A modern congestion pricing policy for urban traffic: subsidy plus toll

Railway Engineering Science - Congestion pricing is seen as an effective policy to address traffic congestion. In such policies where money, people and authorities are involved, the success...     

Global solution approaches in equilibrium and stability analysis using homotopy continuation in the complex domain

Recently, significant attention has been shown to physical and chemical equilibrium and stability analysis in the real and complex domains. In this work, a new procedure involving the continuation method in the complex domain using bifurcation theory is propounded. Based on this method, homotopy branches in real and complex space are connected to each other through bifurcation branches. Thus, by just one initial guess, multiple solution branches are found. When calculations are only made in the real domain, multiple solutions are not always found from an arbitrary initial guess. Examples are presented to show the application of the method to nonlinear sets of equations in phase equilibrium, chemical and phase equilibrium, and stability analysis. These types of problems are believed to contain significant nonlinearities in process simulations. The results can be applied to flowsheet calculations.     

Platinum(VI) dihydroxo tetramesitylporphyrin; characterization and chemical reactivity

Tetramesitylporphyrin platinum(VI) dihydroxo complex, TMPPt(OH)₂ · 2 benzoate was synthesized by addition of two equivalent of meta-chloroperbenzoic acid molecules to the tetramesitylporphyrin platinum(II). This complex was characterized by X-ray diffraction and spectroscopic methods, and is capable to convert two molecules of triphenylphosphine to triphenylphosphine oxide.