Microhardness and morphologic characteristics of rapidly solidified Al-12Si-8Ni-5Nd alloy

Al-Si-Ni-Nd alloys with a nominal composition of Al-12 wt.% Si-8 wt.% Ni-5 wt.% Nd alloy are prepared by a conventional casting (ingot) and melt spinning technique at different cooling rates (ν). The effects of the rapid solidification rate on the microstructures and microhardness performances of the specimen alloys are investigated in detail. The results obtained by the XRD, SEM and DSC show that the ingot and melt spun alloys have a multiphase structure. When ν is 5 m/s, the alloy consists of four phases namely α-Al, intermetallic Al₃Ni, Al₁₁Nd₃, and fcc Si. The melt-spun ribbons are completely composed of α-Al and eutectic Si phases, and primary silicon is not observed when ν increases to 20 m/s, 25 m/s, 30 m/s and 35 m/s. The XRD analysis indicated that the solubility of Si in the α-Al matrix increases greatly with the rapid solidification. The change in microhardness is discussed based on the microstructural observations. The microhardness values of the melt spun ribbons are about three times higher than those of ingot counterparts.     

Mesua ferrea L. seed oil based amido‐amine modified nanoclay/epoxy nanocomposites

Hydrophilic bentonite and organo‐montmorillonite (OMMT) have been modified by using a vegetable oil based amido‐amine compound. The modified nanoclays were characterized by using X‐ray diffraction (XRD) and FTIR techniques. Increase in the basal spacing after the modification was observed in both the cases. Further, Mesua ferrea L. seed oil based sulfonated epoxy resin nanocomposites have been prepared by using these modified nanoclays [3 (w/w) of clay in each case]. The XRD, TEM, SEM, FTIR, and rheological studies confirmed the formation of partially exfoliated nanocomposites. The study also confirmed that hydrophilic bentonite is not suitable nanofiller for the system, though modified bentonite slightly improves the performance characteristics of the pristine polymer. Modified OMMT based nanocomposite shows significant improvement in tensile strength (～ 1.7 times), scratch hardness (～ 2 times), gloss (14 units), and thermal stability (18°C) compared to the pristine system. This nanocomposite also exhibit better performance than OMMT based analogous nanocomposite. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Jute‐fiber‐reinforced polyurethane green composites based on Mesua ferrea L. seed oil

Two types of environmentally friendly jute‐fiber‐reinforced green composites based on Mesua ferrea L. were prepared with poly(urethane ester) and poly(urethane amide) resin blends with commercially available partially butylated melamine–formaldehyde and epoxy resins through solution impregnation and hot‐curing methods. The composites were cured at a temperature of about 130–140°C under a pressure of 35 ± 5 kg/cm² for about 2 h. The mechanical properties, such as tensile strength, flexural strength, elongation at break, hardness, and density, of all of the composites were measured and compared. The mode of interaction between the filler and the matrix were studied by Fourier transform infrared spectroscopy and scanning electron microscopy of the fractured composite samples. The water uptake in different chemical media was observed, and we found that all of the composites possessed excellent hydrolytic stability against almost all of the media except the alkali. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to analyze the thermal behavior of the composites. TGA of the composites showed degradation much above that of the virgin blends, which indicated their high thermostability. The glass‐transition temperatures, as shown by DSC analysis, were found to be much higher. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Reliability and fatigue life evaluation of railway axles

The axle is one of the most important components of a rail vehicle which transmits the weight of the vehicle to the wheels, meets the vertical and horizontal loads formed during static and dynamic moving, and carries the driving moment and braking moment. The prediction of fatigue failure of axles plays an important role in preventing fatigue fractures. Varying loads on components lead to cumulative failure in the mechanism. In this study, failures in axles of rail vehicles serving the Istanbul Transportation Co. have been investigated. Statistical evaluation of real life values has been performed by taking into account the kilometer and load cycle. Equivalent stresses have been used to derive life equations and diagrams by using one of the cumulative life theories known as the Palmgren-Miner method. Finally, theoretical and practical Wohler diagrams S-N (σ-N: stress-life) have been plotted to reveal error calculation.     

Synthesis and characterization of a novel hyperbranched polyether

A hyperbranched polyether has been synthesized by a single‐step nucleophilic displacement polymerization technique between cyanuric chloride and the sodium salt of bisphenol‐A. The effects of various reaction parameters on the yield, and molecular weight, as measured by the intrinsic viscosity of the polymer, have been studied. The synthesized polymer has been characterized by FT‐IR, UV and ¹H NMR spectroscopies, elemental analysis, solubility and viscosity measurements. The polymer is soluble in highly polar solvents such as N,N‐dimethylacetamide, N,N‐dimethylformamide and dimethyl sulfoxide, partially soluble in dilute aqueous NaOH solution, methanol, ethanol, chloroform, etc., but insoluble in water and non‐polar hydrocarbon solvents. The solubility parameter of the hyperbranched polymer has also been measured experimentally. Copyright © 2004 Society of Chemical Industry     

Effect of the NCO/OH ratio on the properties of Mesua Ferrea L. seed oil‐modified polyurethane resins

A series of polyurethane resins with varying NCO/OH ratios (0.8–2.0) has been synthesized from the monoglyceride of Mesua Ferrea L. seed oil, poly(ethylene glycol) (M_n, 200 g mol^?1) and 2,4‐toluene diisocyanate in the presence of dibutyl tin dilaurate as the catalyst. The effects of the NCO/OH ratios of the synthesized resins on the physical properties, such as hydroxy values, acid values, saponification values, iodine values, specific gravities and isocyanate values have been studied. The formation of the polyurethane resins was confirmed by viscosity measurements, and FTIR, UV and ¹H NMR spectroscopic studies. Performance characteristics, such as impact resistance, flexibility, gloss, hardness, adhesive strength and chemical resistance, of the cured resins were investigated as a function of the varying NCO/OH ratios, with an influence of these ratios being observed for most of the above properties. Thermogravimetric analysis (TGA) demonstrated that the thermal stabilities of the cured resins increased with an increase in the NCO/OH ratios. The amounts of char residues at 550 °C were also found to be greater for higher NCO/OH ratios of the oil‐modified polyurethane resins. Copyright © 2005 Society of Chemical Industry     

Comparison of physicochemical characteristics and photofermentative hydrogen production potential of wastewaters produced from different olive oil mills in Western-Anatolia,Turkey

Olive oil extraction produces a dark-colored wastewater that contains nutrients that can be further processed using biotechnology, in parallel with treatment for disposal. For instance, olive mill wastewater (OMW) can be used as a substrate for photofermentative hydrogen production by purple bacteria. A comparative study was investigated with several OMW samples from different olive oil mills in Western-Anatolia, Turkey. The composition of OMW varies significantly for each mill; thus, a detailed physicochemical analysis of each sample has been carried out. Subsequently, samples were assessed for their functioning in anaerobic photofermentative hydrogen production by Rhodobacter sphaeroides O.U.001. The highest hydrogen production potential (19.9 m³ m^?3) was obtained by the OMW sample with the highest organic content (mainly acetic acid, 9.71 kg m^?3) and the highest carbon-to-nitrogen (C/N) molar ratio (73.8 M M^?1). The organic content was found to be composed of primarily acetic, aspartic, and glutamic acids. There was a linear relationship between C/N ratio and hydrogen production potential across the different OMW samples. This study is unique due to the wide range of analyses of OMW samples and the comparison of many parameters for hydrogen production from wastewater. The results obtained throughout this study can aid in the design of systems using wastewater for biohydrogen production. Particularly, the C/N ratio was found to be the best parameter for choosing a proper substrate.     

One-step approach to prepare magnetic iron oxide/reduced graphene oxide nanohybrid for efficient organic and inorganic pollutants removal

An environmentally friendly effective technique was demonstrated to prepare iron oxide/reduced graphene oxide nanohybrid (IO/RGO) at room temperature by using banana peel ash aqueous extract as the base source and Colocasia esculenta leaves aqueous extract as the reducing agent. The nanohybrid was characterized by Fourier transform infrared spectroscopy, X-ray diffractometry, transmission electron microscopy, vibrating sample magnetometry, Raman spectroscopy and thermal studies. The results indicated the decoration of superparamagnetic IO nanoparticles on the surface of the RGO. Both organic and inorganic pollutants were effectively removed from the contaminated water (for Pb²⁺ and Cd²⁺ within 10 min, whereas for tetrabromobisphenol A within 30 min) by IO/RGO. The study revealed that adsorption followed pseudo-second order kinetics and isotherms were well described by the Langmuir model in all the cases. The thermodynamics parameters (ΔG°, ΔS° and ΔH°) were calculated from the temperature dependent isotherms and indicated that the adsorptions were endothermic and spontaneous.     

Mesua ferrea L. seed oil based acrylate-modified thermostable and biodegradable highly branched polyester resin/clay nanocomposites

Mesua ferrea L. seed oil based highly branched polyester resin was modified by methyl methacrylate through grafting polymerization technique. The nanocomposites of this acrylate-modified polyester and 1–5 wt% loadings of organically modified montmorrilonite (OMMT) nanoclay were prepared by an ex situ technique using strong mechanical mixing and ultrasonication. Formation of nanocomposites was confirmed by X-ray diffractometeric (XRD), scanning electron microscopic (SEM) and transmission electron microscopic (TEM) analyses. The absence of d_{0 0 1} reflections of OMMT in XRD and TEM study revealed the partial exfoliation of OMMT by the polymer chain. The homogeneous surface morphology was also ascertained from SEM. Mechanical and thermal studies of the nanocomposites showed an appreciable improvement in tensile strength and thermal stability by OMMT loading. The enhancement of tensile strength by 2.5 times and thermal stability by 32 °C for 5 wt% OMMT filled nanocomposite was observed compared to that of pristine system. The rheological behavior of the nanocomposites was also investigated and shear thinning was observed. Biodegradation of the nanocomposite films was assayed using two strains of Pseudomonas aeruginosa, SD2 and SD3 and one strain of Bacillus subtilis, MTCC736. The nanocomposites exhibited enhanced biodegradability as compared to pristine acrylate modified polyester. All the results showed the potentiality of the nanocomposites as advanced thin film materials for suitable applications.     

Degradation of CI Reactive Red 141 by heterogeneous Fenton‐like process over iron‐containing ZSM‐5 zeolites

The Fenton‐like oxidation of CI Reactive Red 141 was investigated over iron‐containing ZSM‐5 zeolites. Iron was loaded by ion exchange or through hydrothermal synthesis. The oxidation process was carried out in an aqueous solution using hydrogen peroxide as the oxidant. The catalyst prepared by ion exchange with a silicon/aluminium ratio of 42 zeolite showed the highest activity (97% decolorisation and 52% chemical oxygen demand reduction at an initial pH of 3.5) after an oxidation duration of 2 h. The chemical oxygen demand reduction increased with the increasing amount of iron loaded to the zeolite. The FeZSM‐5 catalyst, prepared by hydrothermal synthesis in the presence of oxalic acid, showed very good activity in terms of mineralisation (99% of chemical oxygen demand reduction). The iron leaching was noticeably low (below the European Union directives of 2 mg dm^?3) for the above‐mentioned catalysts.