Poly(o-Toluidine)-Li Nanocomposite: Facile Preparation and Utilization in Energy Storage Devices

ABSTRACT

A facile and a novel method for synthesis of poly(o-toluidine)-Li nanocomposite, in an aqueous medium, by in-situ method, has been reported. The composite has been synthesized using green route method and explored as a material for energy storage. Characteristics of the synthesized nanocomposite have been studied using Fourier transform infraredspectroscopy, X-ray diffraction, cyclic voltammetry, ultraviolet-visible spectroscopy, and field emission scanning electron microscopy techniques. The material obtained has been tested for use in rechargeable batteries as an electrolyte. The charge and discharge performance of the rechargeable battery with the prepared material has been investigated. The battery using the prepared composite material depicted a power density of 362.88 W/m³.     

Living tandem free radical polymerization of a liquid crystalline monomer

Treatment of 1-β-(4′-acetylphenyl)vinyl-3-vinyl-1,1,3,3-tetramethyldisiloxane (I) (an AB₂ monomer) with dihydridocarbonyltris(triphenylphosphine)ruthenium (Ru) leads to a hyperbranched material, poly[1-β-(4′-acetylphenyl)vinyl-3-vinyl-1,1,3,3-tetramethyldisiloxane] (II). I has been prepared by a Pd catalyzed Heck reaction between 4-bromo-acetophenone and 1,3-divinyl-1,1,3,3-tetramethyldisiloxane. The structure of the soluble hyperbranched material (II) has been determined by ¹H, ¹³C and ²⁹Si NMR, as well as by IR and UV spectroscopy. It has also been characterized by GPC, TGA, DSC and elemental analysis. Polymerization occurs by Ru catalyzed addition of the aromatic C−H bonds which are ortho to the activating acetyl group of I across the C−C double bond of the terminal Si-vinyl group in an anti-Markovnikov manner. Received: 8 September 1997/Revised version: 19 October 1997/Accepted: 20 November 1997     

Early hydration of white Portland cement in the presence of bismuth oxide

Abstract

Abstract

Mineral trioxide aggregate (MTA) is a clinical product comprising a mixture of 80 wt-% Portland cement and 20 wt-% bismuth oxide, which is used as a root-filling material in dentistry. The influence of bismuth oxide on the hydration reactions of Portland cements is not well understood. In this study, the impact of 20 wt-% replacement of bismuth oxide on the hydration of white Portland cement was monitored by powder X-ray diffraction (XRD), ²⁹Si and ²⁷Al magic angle spinning nuclear magnetic resonance spectroscopy (MAS NMR) and transmission electron microscopy (TEM). The findings of this research have confirmed that bismuth oxide is an inert additive in white Portland cement, which does not participate in the hydration reactions.     

Twenty Four-Hour PC-BOSS Air-Monitoring Results from the NETL Fine-Particulate Sampling Site in Pittsburgh,Pennsylvania: An Annual Perspective

The concentration and composition of PM _2.5 from May to September of 2000 and monthly trends in ambient fine-particulate material concentrations from October 1999 through December 2000 at the National Energy Technology Laboratory's airmonitoring site in Pittsburgh are reported. Twenty four-hour integrated samples were collected using the Particle Concentrator-Brigham Young University Organic Sampling System (PC-BOSS), a multichannel integrated diffusion denuder sampler designed for routine determination of the chemical composition of ambient particulate matter. The fine-particulate pollutants determined were sulfate estimated as ammonium sulfate, nonvolatile organic material, semivolatile organic material lost from particles during sampling, elemental carbon, nitrate estimated as ammonium nitrate, including ammonium nitrate lost from particles during sampling and elemental content determined by PIXE (for a limited number of samples). Episodes with elevated sulfate and organic material (both semivolatile and nonvolatile) concentrations were seen throughout this period. For the purpose of this discussion, an episode was defined as all times when 3 h average TEOM monitor PM _2.5 concentrations exceeded 30 μg/m³. The use of estimated back-trajectories indicated that during the periods for which these elevated concentrations were observed, pollutants were transported predominantly from the Southwest from the Ohio River Valley to the sampling site. For days when fine particulate episodes occurred, back-trajectory computations were derived for time intervals for which PM _2.5 TEOM concentrations exceeded 30 μg/m³. However, for nonepisode days, back trajectories were computed over a 24 h period. Average PC-BOSS–constructed PM _2.5 concentration (including semivolatile components lost from particles during sampling) for the period from October 1999 through December 2000 was 19 μg/m ³ , excluding crustal material concentration.     

Synthesis of rGO/nanoclay/PVK nanocomposites,electrochemical performances of supercapacitors

ABSTRACT

In this study, graphene oxide (GO) was chemically reacted with sodium borohydride (NaBH₄) to form reduced graphene oxide (rGO). rGO, Montmorillonite nanoclay, and polyvinylcarbazole (PVK) were used to form a ternary nanocomposite via chemical reaction. These nanocomposite qualities were described via scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), Fourier transform infrared spectroscopy-attenuated transmission reflectance (FTIR-ATR). In addition, these materials were used in supercapacitor device as an active material to test electrochemical performances via cyclic voltammetry (CV), galvanostatic charge–discharge (GCD), and electrochemical impedance spectroscopy (EIS). The rGO/nanoclay/PVK nanocomposite shows significantly improved specific capacitance (C_sp = 168.64 Fg^?1) compared to that of rGO (C_sp = 63.26 Fg^?1) at the scan rate of 10 mVs^?1 by CV method. The enhanced capacitance results in high power density (P = 5522.6 Wkg^?1) and energy density (E = 28.84 Whkg^?1) capabilities of the rGO/nanoclay/PVK nanocomposite material. The addition of nanoclay and PVK increased the specific capacitance of rGO material due to a dopant effect for supercapacitor studies. Ragone plots were drawn to observe energy and power density of supercapacitor devices. The C_sp of rGO/nanoclay/PVK nanocomposite has only 86.4% of initial capacitance for charge/discharge performances obtained by CV method for 5000 cycles.     

Polyoxometalate (POM) Oxidation of Milled Wood Lignin (MWL)

Abstract

The chemical structural changes of Lodgepole pine milled wood lignin (MWL) before and after polyoxometalate (POM) oxidation were investigated using gel permeation chromatography (GPC), Fourier Transform infrared spectroscopy (FTIR), and solution‐state nuclear magnetic resonance spectroscopy (NMR). ¹³C NMR spectroscopic data revealed an approximately 28% decrease in α‐OH/β‐O‐4 inter‐unit linkages after POM treatment. This was accompanied by an increase in carbonyl and phenolic hydroxyl content. These results suggest POM oxidation involved side chain (such as α‐OH/β‐O‐4) oxidation and/or degradation of some of the inter‐unit linkages. Quantitative ¹³C NMR along with GPC analysis revealed an increase in the degree of condensation of the MWL as a result of POM treatment, suggesting radical coupling as a major reaction pathway.     

CMC material for train brake systems

Abstract

A continuous carbon fibre/silicon nitride matrix composite material has been produced by an inexpensive method. According to this method, the space between 2D carbon fibre preforms is filled with a S₃ N₄ powder by a pressure infiltration method. High particle packing densities are achieved within the fibre preforms in this way. The compact body is heat treated to form a porous framework without shrinkage, and is then strengthened with an inorganic matrix synthesised from a liquid pre-ceramic polymer. The densification degree, microstructure, and thermal and mechanical properties of the composite material are characterised. The C/Si₃ N₄ composite material pyrolysed at 1300°C is considered to be a very promising material for low temperature applications such as brake discs for rapid train systems.     

Effect of Wood Welding Process on Chemical Constituents of Australian Eucalyptus

Thermochemical changes occurring during wood welding were investigated in Eucalyptus saligna and Eucalyptus pilularis. Unwelded reference wood and material from welded interface were compared via Py-GC/MS, thermogravimetric analyses, X-ray photoelectron spectroscopy, and attenuated total reflection Fourier transform infrared spectroscopy to explain differences in mechanical properties of welded wood between species. It appeared that the species originally containing more condensed substructures also provided stronger joints. The condensation index after welding allowed validating that the adhesive properties of lignin are more accessible in such species. The presence of more carbonyl functions, attributed to carbohydrate solicitation during welding process, potentially made lignin less accessible. Changes following welding were evidenced by the contribution of extractive compounds, fatty acid chains, and terpenoids, possibly reacting with hydroxyl groups and leading to adhesive properties by chemical linkage through new covalent bonds formation. Results corroborate the better mechanical properties of E. saligna, providing stronger joints possibly due to more accessible adhesive properties by esterification between lignin and fatty acid.     

Phosphate removal,mechanism, and adsorption properties of Fe-Mn-Zn oxide trimetal alloy nanocomposite fabricated via co-precipitation method

ABSTRACT

Fe-Mn-Zn oxide trimetal alloy nanocomposite (FMZONC) fabricated and surface properties of the composite material revealed via several characterization methods. Porous nature and alloy type mixing of metals deduced from transmission electron microscopy analysis. Field emission scanning electron microscopy image revealed composite material is of size between 7 and 16 nm. The adsorption properties investigated through isotherm and kinetic experiments. In addition, pH effects and desorption properties were also studied. Maximum adsorption capacity (q max) 149 mg/g for phosphate removal observed at pH 6 and 0.20 g/L of adsorbent. Chemical interaction between metal hydroxide and phosphate elaborated from Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS).     

Investigation of Pressure-Induced Changes in the Chromatographic Selectivity of Methyl and Ethyl Orange on Silica Gel

Abstract

With water as the solvent and two azo dyes as the exemplary solutes, the modification of selectivity through pressure-induced changes in column equilibria has been shown to be significant using a chromatograph capable of going to 4000 kg/cm². Data from high-pressure conductance, spectroscopy, adsorption chromatography, and steric-exclusion chromatography indicated that the primary contribution to the pressure shifts in selectivity was occurring in the bulk solution. An explanation correlating the various experimental observations is offered.     

Fractionation-Purification,IR, 1H 13C NMR Spectral and Property Studies of an Industrial Based Sludge Lignin

Abstract

A flow scheme was devised for the fractionation-purification of sludge lignin material (mixture of hardwood and softwood) used in the synthesis of a hardboard adhesive. Infrared spectroscopy, proton and carbon-13 nuclear magnetic resonance spectroscopy was used to assign the structure of the sludge lignin. The structural characterization indicated appreciable bond cleavage-rearrangement, and subsequent generation of additional acidic/ketone linkages, p-hydroxyphenyl units and saturated hydrocarbons. Additionally, the sludge lignin based extracts showed good adhesive bonding properties when used in a blend.     

FT–Raman Investigation of Milled-Wood Lignins: Softwood,Hardwood, and Chemically Modified Black Spruce Lignins

Abstract

Raman spectroscopy is being increasingly applied to study wood and other lignin-containing biomass/biomaterials. Lignin's contribution to the Raman spectra of such materials needs to be understood in the context of various lignin structures, substructures, and functional groups so that lignin-specific features could be identified and the spectral information could be interpreted usefully. Additionally, to enhance the utility of Raman as a characterization tool, an understanding of chemical-treatment-induced changes to the lignin spectrum is important. In the present work, Raman spectra of four milled-wood lignins (MWLs)—black spruce, loblolly pine, aspen, and sweetgum—were compared, and using black spruce MWL, spectral changes brought about by alkaline hydrogen peroxide bleaching, hydrogenation, acetylation, and methylation reactions were analyzed. The band intensity changes depended upon the nature of the chemical treatments.     

In-Situ Internal Reflection Spectroscopy for the Study of Surfactant Adsorption Reactions Using Reactive Internal Reflection Elements

Abstract

Infrared spectroscopy has been one of the most useful experimental techniques for the analysis of surface reactions. In particular, Fourier transform infrared (FTIR)/internal reflection spectroscopy (IRS) is most often used for in-situ studies. To date, three FTIR/IRS methods have been used for in-situ measurements. These techniques are evaluated for use in the characterization of surface reactions common to flotation systems. The method which uses mineral crystals as reactive internal reflection elements (IREs) is of particular interest because it allows surfactant adsorption densities to be calculated directly from in-situ spectral data in real time, and is the focus of this paper.

Application of in-situ FTIR/IRS with reactive IREs is demonstrated for collector adsorption reactions in each of the four major flotation systems. Also, the use of reactive IREs in the near-IR spectral region and in spectroelec-trochemical research is discussed.     

Ultra-high molecular weight polyethylene – Evidence for a three-phase morphology

The phase composition of ultra-high molecular weight polyethylene of two different molecular weights has been estimated using Raman spectroscopy. Materials have then been irradiated in air to give a received doses of 3.5 and 10 Mrad, and crystallinity change with time has been monitored by differential scanning calorimetry (DSC), wide and small angle X-ray diffraction (WAX and SAX) and Raman spectroscopy. Analysis by DSC and X-ray diffraction involved melting and re-crystallisation. Raman spectroscopy demonstrated that the material consists of three phases, fully crystalline, fully amorphous and an intermediate all-trans non-crystalline phase. Following irradiation the mass fraction of this latter phase reduces as total crystal content increases. SAX results indicate a refinement of the original lamellae and the emergence of a population of smaller crystals. It is thought that the all-trans material exists as an interfacial phase and that scission within this phase facilitates the observed crystal changes.     

Synthesis,Characterization, and Exploration of Antimicrobial Activity of Copper Complex of Diamide Derivative of p-tert-butylcalix[4]arene

Calixarenes are a versatile class of compounds, which possesses wide applications in various fields including biological as well as pharmaceutical sciences. In the present study, amide derivative of calix[4]arene (3) was synthesized and characterized by modern analytical techniques such as elemental analysis and Fourier transform infrared spectroscopy (FT-IR). Complexation property of 3 with essential metals was explored by UV-Vis spectroscopy. The results revealed that 3 shows good selectivity toward Cu²⁺. Job's plot analysis suggests that 3 forms complex with Cu²⁺ in 1:2 stoichiometric ratio. Antimicrobial activity of 3 and its Cu²⁺ complex was also determined and it was observed that 3 is more efficient against R. stolonifer as compared to its action against bacteria, because for fungus it shows “Minimum Inhibitory Concentration” (MIC) value equal to 1.5 µg/mL, while for bacteria MIC is 3 µg/mL. However, it was found that complex is more efficient in action than 3. Oxidation state of metal, overtone concept, and Tweedy's chelation theory justifies the increased activity of metal complex. Cu²⁺ complex shows higher antimicrobial activity toward Escherichia coli (E. coli) (Gram-negative) bacteria by showing MIC value 0.37 µg/mL. While for Staphylococcus albus (S. albus) (Gram-positive) bacteria and Rhizopus stolonifer (R. stolonifer) fungal species, it shows MIC value equal to 0.75 µg/mL.     

Numerical Molding Simulation for Rapid-Prototyped Injection Molds

Abstract:

Injection molding is a very mature technology, but the growth of layer-build, additive, manufacturing technologies (rapid prototyping, RP) has the potential of expanding injection molding into areas not commercially feasible with traditional molds and molding techniques. This integration of injection molding with rapid prototyping has undergone many demonstrations of potential. What is missing is the fundamental understanding of how the modifications to the mold material and RP manufacturing process impact both the mold design and the injection molding process. In addition, numerical simulation techniques have now become helpful tools of mold designers and process engineers for traditional injection molding. But all current simulation packages for conventional injection molding are no longer applicable to this new type of injection molds, mainly because the property of the mold material changes greatly. In this paper, an approach to accomplish numerical simulation of injection molding into rapid-prototyped molds is established and a corresponding simulation system is developed. For verification, an experiment is also been carried out with an RP fabricated SL mold. Stereolithography (SL) is an original and typical rapid-prototyping method, which is chosen as the study object in the paper.     

“Spontaneous Copolymerization of p-Chlorophenylmaleimide with 2-Methylaziridine”

Abstract

p-Chlorophenylmaleimide as an electrophilic monomer was copolymerized in the absence of initiator with 2-methylaziridine as nuclephilic monomer. The copolymers were characterized by elemental analysis, FT-IR, and ¹H-NMR spectroscopy. The copolymer compositions were determined by chloro elemental analysis and ¹H-NMR spectroscopy. 2-Methylaziridine is more reactive than p-chlorophenylmaleimide yielding statistical copolymers. Mn, determined by vapor pressure osmometry, varied between 3.000 and 6.700 g/mol.     

High Pressure Conductivity and Photoconductivity of Polyveratrole

Summary Electropolymerization of o-(CH₃O)₂C₆H₄ (Veratrole) in dry acetonitrile/tetrabutylammonium tetrafluoroborate at platinum electrode, yields a green polymeric conducting solid. As the pressure is increased, the material becomes more conductive, but sharp changes towards lower conductivity occur at 4.2 and 6.2 metric tons pressure, probably due to phase transitions. The photoconductivity shows an exponential increase as temperature is increased, but it shows reversible changes at 200 K, 225 K and 250 K during slow warming, also attributable to phase transitions. Photoconductivity of Polyveratrole increases with the radiation frequency, being higher under blue light than under red of infrared radiation and there is a linear increase of photoconductivity with radiation density. Conductivity transients show that the conductivity increases exponentially with time to the saturation point within few minutes, and it also decreases exponentially when the light is turned off and the circuit is open. This behaviour can be explained by formation and encounter of electron and hole as current carriers. A preliminary study indicates a piezoelectric effect for the material. absorption spectroscopy allowed the measurements of the material band gap.     

HEAT AND MASS TRANSFER IN IMPINGEMENT DRYING

ABSTRACT

In industrial drying applications, efficient transfer of heat and mass between a drying medium and the material being dried is very critical for the overall economics of the operation. Impinging jets are therefore widely used for their enhanced tmnsport characteristics, especially for drying of continuous sheets of materials such as paper and textiles. In such applications, a thin sheet of material, as wide as 6m in cross machine direction, speeds at velocities as high as 90 km/hr under high velocity jets emerging from a confining surface parallel to the material surface. Many variables and effects need to k considered for proper design of such impinging jet systems: nozzle geometry and size, nozzle configuration, location of exhaust pons, nozzle-to-surface separation, jet-to-jet separation, cross flow, jet exit velocity and surface motion. For permeable materials, additional enhancement of heat and mass transfer that occur when some of the impinging gas is removed through the material makes this option an atmctive one.

Here, we review the above effects and offer predictive correlations from literature which may be used in the design of high velocity impinging jet systems.     

Influence of ionic liquid on the photoelectrochemical properties of ZnO particles

ZnO particles synthesized by the microwave-assisted hydrothermal method were sensitized with different amounts of ionic liquid (IL) 1.3-dimethylimidazolium iodide (MMI.I). The structure of the modified and unmodified ZnO particles were characterized by X-ray diffraction, Raman spectroscopy, field emission gun-scanning electron microscopy (FEG-SEM), ultraviolet-visible (UV–vis) absorption spectroscopy, photoluminescence (PL), and photoelectrochemical measurements. While the sensitization of ZnO particles by the ionic liquid does not change the ZnO phase, it reduces the particle size and converts shallow defects to deep defects. These changes cause the photocurrent density of the ZnO/IL films to increase significantly from 0.05?mA?cm^?2 for pure ZnO to 0.52 and 1.24?mA?cm^?2 for the ZnO films containing 20% and 35% by mass of the IL, respectively, at 1.08?V vs. Ag/AgCl. This about 24-fold increase in the photocurrent density of the ZnO/IL35 sample may indicate that the MMI.I IL may be acting as a dye, since it is constituted by an organic part, MMI⁺. This good performance presented by this sample indicates that this is a promising material for photoanode in solar cells.