Tung oil: An autonomous repairing agent for self-healing epoxy coatings

The capability of the encapsulated Tung oil was investigated as a scratch healing agent for self-healing coatings. Encapsulation of Tung oil with urea–formaldehyde shell was carried out by in situ polymerization. Before the mechanical agitation of microcapsules into epoxy resin, their characteristics were evaluated by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). Released Tung oil from ruptured microcapsules healed the artificial scratch in the coating matrix successfully. Corrosion resistance of healed area was evaluated by electrochemical impedance spectroscopy (EIS) and immersion test; and the results were compared with neat epoxy coating.     

Effects of colloidal properties on sensible heat transfer in water-based titania nanofluids

Nanofluids have attracted considerable attention in recent years as effective working fluids in heat transfer applications. Nanofluids are essentially suspensions of nanoparticles in a base fluid and exhibit higher thermal conductivity than conventional heat transfer fluids.     

Preparation of thermally stable,low dielectric constant,pyridine‐based polyimide and related nanofoams

Reaction of 6‐chloronicotinoyl chloride with p‐phenylene diamine resulted in preparation of a dichloro diamide compound. Subsequently, chloro displacement of this compound with 4‐amino phenoxy groups led to production of a new pyridine‐based ether diamine named as N,N′‐(1,4‐phenylene)bis(6‐(4‐aminophenoxy) nicotinamide). Novel polyimide was prepared through polycondensation reaction of the diamine with hexafluoroisopropylidene diphthalic anhydride (6‐FDA) via two‐step imidization method. In addition, new nanoporous polyimide films were produced through graft copolymerization of polyimide as the continuous phase with a thermally labile poly (propylene glycol) oligomer as the labile phase. The grafted copolymers were synthesized using reaction of the diamine and 6‐FDA in the presence of poly (propylene glycol) 2‐bromoacetate as thermally labile constituent via a poly(amic acid) precursor process. The labile block was decomposed via thermal treatment to release inert molecules that diffused out of the matrix to leave pores with diameters between 30 and 60 nm. The structures and properties of polyimide and polyimide nanofoams were characterized by different techniques including ¹H‐NMR, FTIR, TGA, DMTA, SEM, TEM, dielectric constant, and tensile strength measurement. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and characterization of new molecular imprinting poly[1-(N,N-bis-carboxymethyl)amino-3-allylglycerol-co-dimethylacrylamide] for selective sorption and determination of cefuroxime sodium in biological and pharmaceutical samples

Two molecular imprinting polymers (MIPs) based on solution and suspension polymerization were prepared with 1-(N,N-bis-carboxymethyl)amino-3-allylglycerol and N,N-dimethylacrylamide as functional monomers, and copper ion-cefuroxime sodium complex as the template. The imprinted polymers were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, elemental analysis, Brunauer, Emmett and Teller method and scanning electron microscopy. The effects of the analytical parameters such as sample pH, contact time on sorption capacity of the polymeric sorbent and interfering drugs were investigated and compared for both polymers with different polymerization methods. The imprinted polymer sorbent was selective for the template. The profile of cefuroxime sodium uptake by the both sorbents reflects good accessibility of the active sites in the imprinted polymer sorbents. The equilibrium adsorption data of cefuroxime sodium on polymeric sorbents were analyzed by Langmuir, Freundlich, Temkin and Redlich–Peterson isotherm models. The developed method was utilized for determination of cefuroxime sodium in pharmaceutical and fluids biological samples like human plasma and urine by high performance liquid chromatography with satisfactory results.     

Numerical analysis of transport phenomena for designing of ejector in PEM forklift system

In the present study, Computational Fluid Dynamics (CFD) technique is used to design an ejector for anode recirculation in an automotive PEMFC system. A CFD model is firstly established and tested against well-documented and relevant solutions from the literature, and then used for different ejector geometries under different operating conditions. Results showed that a single ejector with optimized geometry cannot cover the required recirculation in the entire range of the fuel cell current. Having two ejectors for different ranges of currents is thus proposed as an alternative solution in which the system can better take the advantage of ejectors for recirculation purpose. In addition, the operating mode of one variable nozzle ejector has been investigated and compared with aforementioned cases. The results showed that the variable nozzle ejector can work in the same operational mode as in the case with two ejectors. However, in practice, the latter one needs a more complicated control system and it is more difficult to manufacture.     

Basis weight uniformity analysis in nonwovens

It is widely recognized that nonwoven basis weight uniformity affects various properties of nonwovens, including appearance, physical properties, or mechanical properties. However, it is one of the nonwoven characteristics that is most difficult to characterize. This paper reports on the methodology based on the well-known quadrant method that objectively quantifies uniformity of nonwoven fabrics.     

Effect of enzymatic and mechanical treatment on combined desizing and bio-polishing of cotton fabrics

The main objective of this study was to improve the enzymatic effect by mechanical treatment on cotton fabric in combined desizing and bio-polishing. The purpose is to create a commercially and environmentally friendly process for water and energy saving. The effect of mechanical treatment and different enzyme concentration was studied. Both mechanical and enzymatic treatment effect were evaluated through measuring weight loss and light measurement of fabric surface. Fabric surface evaluation also was done via photo micrographing. Fabric hairiness was illustrated on captured photos of treated and untreated fabric. Finally, optimized data of treatment were obtained.     

Evaluation of Mass Exchange During Osmotic Dehydration of Plum Using Response Surface Methodology

Water loss (WL), solid gain (SG), weight reduction (WR) and shrinkage were quantitatively investigated during osmotic dehydration of plum using response surface methodology with the sucrose concentration (30–60g/100 g sample), temperature of sucrose solution (40–60°C) and immersion time (60–240 min). Experiments were designed according to Central Composite Rotatable Design with these three factors. For each response, second order polynomial models were developed using multiple linear regression analysis. With respect to water loss, solid gain, weight reduction and shrinkage, both linear and quadratic effects of four variables were found to be significant. In most cases, an increase of sucrose concentration, temperature and immersion time increased WL, SG, WR and shrinkage, except the increasing of immersion time for osmotic treatment has no effect on shrinkage. It was found that immersion time and temperature were the most significant factors affecting the WL during osmotic dehydration of plum followed by concentration of sucrose solution. This was also true for WR. Effect of temperature and time were more pronounced for SG than the concentration of sucrose solution.     

Optimistic Selection of Cluster Heads Based on Facility Location Problem in Cluster-Based Routing Protocols

Cluster-based routing protocols are one of the most favorable approaches for energy management in wireless sensor networks. The selection of the best cluster heads (CHs), as well as the formation of optimal clusters, is an NP-hard problem. The present study proposes an optimal solution for CHs selection to generate a network topology with optimized network performance. The problem is formulated as facility location problem and a linear programming model is used to solve the optimization problem. Results of analysis o the network simulator (NS2) indicate that applying this method in cluster-based routing protocols prolongs 16 % of the network lifetime, increases 15.5 % of data transmission and improves 5.5 % of throughput, as compared to the results of current heuristic methods such as LEACH, DEEC and EDFCM protocols.     

A mathematical model for prediction of microporosity in aluminum alloy A356

In the present work, a mathematical model was developed based on finite difference method to predict the microporosity distribution in A356 aluminum alloy casting. Heat, mass, and gas conservation equations were solved in this model. Moreover, Darcy’s equation was considered in the mushy zone. Results show that the distribution and concentration of microporosities in cast parts vary with both cooling rate and initial gas content. Simulation results were compared with experimental data where proportionally good agreement with experimental results was found. Finally, a complex cast part was simulated presenting the ability of the model to predict the porosities in industrial cast parts.