Polystyrene-bound dioxirane: a new class of recyclable oxidising reagent

Polystyrene-bound dioxirane containing a five-methylene spacer arm between the polymer matrix and reagent function has been prepared and investigated as a new class of recyclable oxidising reagent for various organic substrates. The new reagent was found to oxidise alkenes to epoxides, pyridines to N-oxides and amines to nitro compounds in near-quantitative yields. The spent reagent could be regenerated to the dioxirane resin by a simple reaction without considerable loss in reactivity.     

Flow behavior of LDPE and its blends with LLDPE I and II: A comparative study

Studies on melt rheological properties of blends of low density polythylene (LDPE) with selected grades of linear low density polyethylene (LLDPE), which differ widely in their melt flow indices, are reported. The data obtained in a capillary rheometer are presented to describe the effects of blend composition and shear rate on flow behavior index, melt viscosity, and melt elasticity. In general, blending of LLDPE I that has a low melt flow index (2 _g/10 min) with LDPE results in a decrease of its melt viscosity, processing temperature, and the tendency of extrudate distortion, depending on blending ratio. A blending ratio around 20–30% LLDPE I seems optimum from the point of view of desirable improvement in processability behavior. On the other hand, blending of LLDPE II that has a high melt flow index (10_g/10 min) with LDPE offers a distinct advantage in increasing the pseudoplasticity of LDPE/LLDPE II blends. © 1996 John Wiley & Sons, Inc.     

Nose radius oblique tool: Cutting force and built-up edge prediction

A semi-empirical machining theory is described for predicting cutting forces and temperatures for oblique nose radius tools from cutting conditions and a knowledge of work material flow stress and thermal properties. By defining an equivalent cutting edge based on the chip flow direction, predictions are made for different cutting conditions and tool geometries (nose radii and rake angles in particular). It is shown how the cutting conditions giving a built-up edge can be determined from the predicted temperatures. For finishing conditions a comparison between predicted and experimental results is made and this shows good agreement.     

Characterization of crystal field and nuclear quadrupole interactions in the D1 state of Am in LaCl3 and CaWO4

The crystal field splitting and hyperfine energy level structure in the first ⁵D₁ excited state of ²⁴³Am³⁺ in LaCl₃ and CaWO₄ have been studied using selective laser excitation, Zeeman and spectral hole burning experiments. Two crystal field levels and associated vibronic structures were observed in the electric dipole forbidden ⁷F₀↔⁵D₁ transition, that has a very weak magnetic dipole moment. The hyperfine energy level structure, including nuclear quadrupole splitting, was resolved in spectral hole burning studies. The existing free ion and crystal field interaction model provides a consistent interpretation of the observed ordering of crystal field levels and the magnitude of the nuclear quadrupole splitting of ²⁴³Am³⁺ in CaWO₄, whereas a discrepancy between the model and experimental results is encountered for ²⁴³Am³⁺ in LaCl₃. A discussion on the relationship between nuclear quadrupole interaction and free ion modeling is given.     

An applied artificial intelligence approach towards assessing building performance simulation tools

With the development of modern computer technology, a large amount of building energy simulation tools is available in the market. When choosing which simulation tool to use in a project, the user must consider the tool's accuracy and reliability, considering the building information they have at hand, which will serve as input for the tool. This paper presents an approach towards assessing building performance simulation results to actual measurements, using artificial neural networks (ANN) for predicting building energy performance. Training and testing of the ANN were carried out with energy consumption data acquired for 1 week in the case building called the Solar House. The predicted results show a good fitness with the mathematical model with a mean absolute error of 0.9%. Moreover, four building simulation tools were selected in this study in order to compare their results with the ANN predicted energy consumption: Energy_10, Green Building Studio web tool, eQuest and EnergyPlus. The results showed that the more detailed simulation tools have the best simulation performance in terms of heating and cooling electricity consumption within 3% of mean absolute error.     

Evaluation of performance of nanofluid using multiwalled carbon nanotubes for machining of Ti–6AL–4V

Machining of titanium alloys generate very high temperature in the cutting zone. This results in rapid tool wear and poor surface properties. Therefore, improvement in cutting performance in machining of titanium alloys is very much dependent on effectiveness of the cooling strategies applied. In the present work, performance of nanofluid using multiwalled carbon nanotubes (MWCNTs) dispersed in distilled water and sodium dodecyl sulfate (SDS) as surfactant is evaluated for turning operation on Ti–6Al–4V workpieces. Turning operations were carried out under three different conditions – dry, with conventional cutting fluid and with nanofluid. Nanofluid application was limited to 1 L/h and it was applied at the tool tip through gravity feed. Various machining responses like cutting force, surface finish and tool wear were analyzed while turning at optimum cutting parameters as 150 m/min, 0.1 mm/rev and 1 mm depth of cut. Later on, machining performance of nanofluid is confirmed at low cutting speed of 90 m/min. Nanofluid outperformed conventional cutting fluid with 34% reduction in tool wear, average 28% drop in cutting forces and 7% decrease in surface roughness at cutting speed of 150 m/min.     

Importance of fullerenic active sites in surface modification of carbon black by plasma polymerisation

Carbon black is widely used as an active filler in rubber to improve the physical properties. The surface energy of carbon black is high compared to that of various elastomers like Styrene-Butadiene rubber, Butadiene rubber and Ethylene-Propylene Diene rubber. Reducing the surface energy and matching its surface chemistry will aid in compatibilising carbon black with various elastomers. Surface modification of carbon black by plasma polymerisation has been attempted earlier in order to reduce the surface energy of carbon black. These studies have shown that for effective surface modification of carbon black, there should be available a sufficient number of surface active sites. The present paper looks into the possibilities of utilizing the surface activity of a by-product of the production of fullerene, the fullerene soot for its use in a plasma modification process. Thermogravimetric analysis, wetting behaviour with various liquids of known surface tension, time of flight secondary ion mass spectrometry and transmission electron microscopy are used to characterise the carbon black before and after surface modification. The study shows that the fullerenic type structures present on the surface of fullerenic soot act as very active growth sites for the plasma polymer.     

Microwave-Assisted Synthesis of Titania Nanocubes, Nanospheres and Nanorods for Photocatalytic Dye Degradation

TiO₂ nanostructures with fascinating morphologies like cubes, spheres, and rods were synthesized by a simple microwave irradiation technique. Tuning of different morphologies was achieved by changing the pH and the nature of the medium or the precipitating agent. As-synthesized titania nanostructures were characterized by X-ray diffraction (XRD), UV–visible spectroscopy, infrared spectroscopy (IR), BET surface area, photoluminescence (PL), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and atomic force microscopy (AFM) techniques. Photocatalytic dye degradation studies were conducted using methylene blue under ultraviolet light irradiation. Dye degradation ability for nanocubes was found to be superior to the spheres and the rods and can be attributed to the observed high surface area of nanocubes. As-synthesized titania nanostructures have shown higher photocatalytic activity than the commercial photocatalyst Degussa P25 TiO₂.     

Inorganic–organic hybrid materials based on functionalized silica and carbon: A comprehensive understanding toward the structural property and catalytic activity difference over mesoporous silica and carbon supports

Inorganic–organic hybrid materials based on functionalized silica and carbon were synthesized by anchoring molybdovanadophosphoric acid (H₅[PMo₁₀V₂O₄₀] · 32.5H₂O) onto amine-functionalized SBA-15, ethane-bridged SBA-15 and mesoporous carbon, respectively. Small angle X-ray diffraction, N₂ sorption analysis, HRTEM, SEM, FT-IR, CP-MAS NMR were used to diagnose the mesoporous structure of inorganic–organic hybrid materials. The structural integrity of molybdovanadophosphoric acid has been found to be retained after immobilization over mesoporous materials. These inorganic–organic hybrid materials were tested in the environmentally friendly oxidation of 2-methylnaphthalene (2MN) with 30% aqueous hydrogen peroxide. Molybdovanadophosphoric acid containing mesoporous organosilica hybrid material (ethane-bridged SBA-15) exhibited higher catalytic activities in the oxidation of 2MN to give a clean product 2-methy-1,4-naphthoquinone (menadione vitamin K3 precursor), because of the improved hydrophobicity of the material. The correlation between structural properties and catalytic activities of these hybrid materials has been well addressed in our present studies.     

Cuprous oxide nanoparticles in epoxy network: Cure reaction,morphology, and thermal stability

Nanosized cuprous oxide filler particles (nCOP) with octahedral morphology were synthesized through hydrazine reduction method and were used to develop a novel nanocomposites based on epoxy resin. The morphology of epoxy–nCOP nanocomposites were analyzed using transmission electron microscopy and scanning electron microscopy. Differential scanning calorimetry analysis showed that the cure reaction rate of epoxy was found to increase with the addition of the nCOP and a plausible cure reaction mechanism was suggested. The activation energy required for the cure reaction reduced by 22% and 13% at the initial (E₁) and final stage (E₂) of the cure, respectively, by the incorporation of 3 phr nCOP. It was also shown that the kinetically controlled parts of reaction could be expressed well by Kamal's phenomenological model while end of curing process could not be completely expressed by this model as there it was diffusion controlled. The influence of nCOP on glass transition temperature (T_g), mechanical properties, and thermal stability of epoxy matrix was also investigated and the results showed that better characteristics were observed in presence of 3 phr nCOP loading. POLYM. ENG. SCI., 55:2293–2306, 2015. © 2015 Society of Plastics Engineers