Formation Of Composite Materials Research Articles

Study on SO2-Absorption Behavior of Composite Materials for DeSOx Filter From Diesel Exhaust

NOx emitted from diesel engines is one of the major air pollutants in most countries. To reduce NOx emission, NOx storage/reduction (NSR) catalysts have been developed for diesel systems. The catalyst for NSR is strongly poisoned with sulfur. This paper reports the synthesis of Na-doped CaCO3 as a new material for SO2 adsorption. Measurements of the desulfurization breakthrough characteristics using monolith washcoated Na-doped CaCO3 were investigated at 450°C. The Na-doped CaCO3 absorbed ∼77.6–90.6 mg-SO2/g-material of SO2 at 450°C (where CaCO3 is 8 mg-SO2/g-material). Investigation of the source of the improved sulfur absorption capacity of the Na-doped CaCO3 relative to the parent material via x-ray diffraction (XRD) and scanning electron microscopy–energy-dispersive x-ray spectroscopy (SEM-EDX) analyses revealed that the new material forms a composite partially composed of Na2Ca(CO3)2. The enhanced SO2 absorption capacity derived from the formation of composite materials is demonstrated herein. SO2 contained in the exhaust gas is absorbed at a lower temperature than with previously reported systems. In order to elucidate the SO2 absorption mechanism of the composite materials, further studies and synthesis of materials with greater absorption capacity are required.

Utilization of XPS Analysis for the Characterization of Mechanochemical Activation in Polymer-Cement Composite Materials

This paper introduces the X-ray photoelectron spectroscopy (XPS) technique, well applicable for the analysis of the interfacial layer between polyvinyl alcohol and monocalcium aluminate in macro defect-free (MDF) cement. The experimental results explain the chemical reaction mechanism during the mechanochemical process, which is crucial for the formation of those non-traditional polymercement composite materials.

Ionic Liquid-Based Solvents for Natural Fiber Welding: Impact of Solvent System Composition

Certain ionic liquids (ILs) are known to be efficient solvents for biopolymers, in particular for cellulosic and silk based materials1. The ionic liquid solvent efficiency is strongly impacted by the presence of both impurities (e.g., water, residual reagents) and intentional additives (e.g., co-solvents or diluents)3,4. Natural fiber welding (NFW), the process of controlled partial dissolution and regeneration of biopolymers,5-7 is also affected by the presence of impurities and additives8. In this work we investigate the impact of impurities and additives on NFW. The extent of NFW was characterized by x-ray diffraction, ATR-IR, SEM, and mechanical property testing. These data are correlated with solvent physical properties, such as viscosity, density, and surface tension, as well as with solvent properties as indicated by their Kamlet-Taft parameters. For some of the systems investigated, there is a maximum solvent composition where polar aprotic solvents in conjunction with IL are more efficient at NFW than the IL alone. Surprisingly, this composition occurs when the mole ratio of IL to solvent is less than one to one. Understanding the factors that influence welding in these systems allows for greater control over the NFW process and facilitates the formation of functional biopolymer composite materials. References Swatloski, R. P.; Spear, S. K.; Holbrey, J. D.; Rogers, R. D. J. Am Chem Soc, 2002, 124, 4974.Phillips, D. M.; Drummy, L. F.; Conrady, D. G.; Fox, D. M.; Naik, R. R.; Stone, M. O.; Trulove, P. C.; De Long, H. C.; Mantz, R. A. J Am Chem Soc., 2004, 126, 14350.Rinaldi, R. Chem. Commun., 2011, 47, 511.Mazza, M.; Catana, D. A.; Vaca-Garcia, C.; Cecutti, C. Cellulose, 2009, 16, 207.Haverhals, L. M.; Reichert, W. M.; De Long, H. C.; Trulove, P. C. Cellulose, 2010, 2985, 425.Haverhals, L. M.; Sulpizio, H. M.; Fayos, Z. A.; Trulove, M. A.; Reichert, W. M.; Foley, M. P.; De Long, H. C.; Trulove, P. C.Cellulose, 2012, 19, 13.Haverhals, L. M.; Nevin, L. M.; Foley, M. P.; Brown, E. K.; De Long, H. C.; Trulove, P. C. Chem.Commun., 2012, 48, 6417.Haverhals, L. M.; Brown, E. K.; Foley, M. P.; De Long, H.; Trulove P. ECS Trans, 2012, 50, 6

High Tap Density MgO Doping Composite Composition 0.5Li2MnO3-0.5LiNi0.5Mn0.5O2 Cathode Material

Introduction Last decade Lithium-rich layered and spinal base oxide materials have been studied as a promising cathode material for using in the next generation high energy lithium-ion batteries for intensively pursued for electric and hybrid electric vehicle applications. Commercial lithium ion cells are currently made largely with the layered LiCoO2 cathode. However, only 50% of the theoretical capacity of LiCoO 2 can be utilized in practical cells due to the chemical and structural instabilities at deep charge as well as safety concerns. One of these layer materials composite , xLi2MnO3-(1-x)LiNi0.5Mn0.5O2 (0<x<1) has been widely studied since Thackeray et al. discovered it when they were researching the LiMnO2 layered material.1 This material shows capacities larger than 280 mAhg-1 and operating voltages larger than 4.5 V making it one of the cheapest high energy density material for Li-ion batteries. However, many challenges must be overcome in order to realize its commerciality, for example its poor capability and its voltage degradation during cycling.2 In this study, we are doping MgO with composite cathode. The effect of doping not only will provide stability in the composite structure in the lithiation and delithiation process, also improve electrochemical properties.. Experimental0.5Li2MnO3-0.5LiNi0.5Mn0.5O2 has been synthesized using carbonate based co-precipitation method.The structural and morphological features have been studied by powder X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Figure 1 shows the XRD patterns of as-synthesized LNMO powder. Results show the complete two phases formation of composite material corresponding to the two group space of R3m (LiNi0.5Mn0.5O2) and C2/m (Li2MnO3). This patterns were compare with JCPDS database, #84-1634 for Li2MnO3 and #09-0063 for LiNi0.5Mn0.5O2, which have been well indexed on the basis of LiNiO2 structure.1 SEM measurements show highly dense particle agglomerations, particle size lies to 0.5-2 μm, while agglomerations around 10-20 μm. Smaller particles are strongly related with a good electrochemical behavior.Electrochemical properties will be study using cyclic Voltammetry, Charge-Discharge Curves, and Electrochemical Impedance spectroscopy (EIS). These measurements are still in progress.Figure 1. XRD patterns of as prepared LNMO powder. Inset shows the small picks between 20-30 degrees related to the monoclinic Li2MnO3 structure, References[1] Haijin Yu et al., J. Phys. Chem. Lett., 4, 1269 (2013)[2] Gurpreet Singh et al., J. Electrochem. Soc., 159 (4), A3 (2012)

Interplay of carbon–silica sources on the formation of hierarchical porous composite materials for biological applications such as lipase immobilization

The porous inorganic materials, with hierarchical structures, find application in many processes where the chemical stability and pore connectivity are key points, such as separation, adsorption and catalysis. Here, we synthesized carbon–silica composite materials, which combine hydrolytic stability of the carbon with the surface chemical reactivity of silica in aqueous media. The polycondensation of carbonaceous and siliceous species from sucrose, Triton X-100 surfactant and tetraethylortosilicate during the hydrothermal synthesis led to the formation of hydrochar composite materials. The subsequent carbonization process of these composite hydrochars gave carbon–silica hierarchical porous materials. The study of the micellar reaction system and the characterization of the derivate materials (carbon–silica composite, carbon and silica) were carried out. The results indicate that synthesis conditions allowed the formation of a silica network interpenetrated with a carbon one, which is produced from the incorporated organic matter. The control of the acidity of the reaction medium and hydrothermal conditions modulated the reaction yield and porous characteristics of the materials. The composite nature in conjunction with the hierarchical porosity increases the interest of these materials for future biological applications, such as lipase immobilization.

Formation of Aluminum Matrix Composite Material with High-Temperature Reaction of Al–SiO2 System Components

Results are presented for a study of aluminum chemical composition and structure after reaction with silicon dioxide refractory material. It is established that high-temperature reaction of Al–SiO2 system components is accompanied by refractory working surface breakdown and formation of aluminum matrix composite material containing silicon microparticles.

On the theory of combustion and synthesis of composite materials in the field of mass forces

The formation of a composite material during combustion of a two-layer sample in a centrifugal device was studied by mathematical modeling. The liquid combustion products of the upper layer flow into the lower porous layer under the action of the centrifugal force and initiate its combustion to form a composite material. The critical conditions for the passage of the combustion wave from the upper to the lower layer of the sample are determined depending on the gravitational overload and initial porosity. Dependences of the burning velocity and the impregnation depth of the lower layer on its porosity and overload are obtained.

Inexpensive synthesis route of porous polyaniline–ruthenium oxide composite for supercapacitor application

Abstract Porous polyaniline–ruthenium oxide composite has been synthesized using a successive ionic layer adsorption and reaction (SILAR) method. The result of X-ray diffraction indicates the amorphous nature of polyaniline–ruthenium oxide (PANI–RuO2) composite. Fourier transform infrared (FT-IR) and FT-Raman spectroscopy studies reveal the formation of composite material. The morphology of PANI–RuO2 composite observed using scanning electron microscope (SEM) shows hierarchical nanofibers with small particles grown on the nanofibers. The electrochemical measurement shows that PANI–RuO2 composite electrode material yields specific capacitance of 664 F/g and higher capacitance retention (89%) of its initial capacitance after 5000 cycles. The unique structure of PANI–RuO2 composite and the coexistence of conducting PANI with RuO2 are found to be responsible for the superior electrochemical properties.

Sustainable Concrete by Partially Replacing Coarse Aggregate Using Coconut Shell

A common feature of sustainable buildings is that they drastically reduce emissions, material use and water use and with involvement of economic vitality, environmental, health, and social equity in it. As a whole, the study main concern is the environment and the construction and building technology to enhance natural world as well as building materials. In view to provide new knowledge to the contractors and developers on how to improve the construction industry methods and services by using coconut shells and to sustain good product performance and meet recycling goals, there is need to design a technical specification of concrete using coconut shell as aggregates that will meet the Indian standard requirements in order to help contribute to the industry in saving the environment, to encourage the government to find solutions regarding the disposal to landfills of waste materials and save the environment. The use of coconut by products has been a long time source of income for some people. Recycling of the disposed material is one method of treating the agricultural waste. The used of coconut shell could be a valuable substitute in the formation of composite material that can be used as a housing construction,such as concrete.

Some characteristic features of formation of composite material based on KDP single crystal with incorporated Al2O3·nH2O nanoparticles

Composite material based on KDP (KH2PO4) crystal matrix with incorporated aluminum oxyhydroxide Al2O3·nH2O nanoparticles is obtained and peculiarities of the formation of KDP:Al2O3·nH2O composite structure are studied by selective etching, optical and scanning electron microscopy. Influence of the nanoparticles on the formation of defect subsystem is analyzed. The obtained material is shown to have a zonal structure with a period independent of the concentration of nanoparticles. By means of FTIR‐spectroscopy, interaction of nanoparticles with KH2PO4 solution is studied. A model of the capture of nanoparticles by the {100} KDP crystal face is proposed.

In-Situ Raman Spectroscopy and Electrochemical Studies on High Energy Density xLi2MnO3-(1-x)LiNi0.66Co0.17Mn0.17O2 Composite Cathode Materials

Development of high energy density cathode materials is the key to fabricate high power Li-ion batteries (LIBs) capable of meeting high power demands in new applications such as regenerative braking in hybrid electric vehicles, power backup, and portable power tools. Li2MnO3-based composite cathode materials are attracting much attention due to their excellent electrochemical performances [1-5]. In the present work, novel layered-layered composite cathode materials with small amount of cobalt and different amounts of Li2MnO3 e.g. xLi2MnO3-(1-x) LiNi0.66Co0.17Mn0.17O2 where x = 0.3, 0.5, and 0.7 were successfully synthesized by employing sol-gel technique and characterized using advanced techniques to investigate both the structural and electrochemical properties. Powder X-ray diffraction patterns confirmed the formation of layered-layered composite materials revealed by the presence of reflections corresponding to rhombohedral (R3m) and monoclinic (C2/m) space group symmetries. Structural analysis by Raman spectroscopy showed three distinct phonon modes. Peaks centered at 482 cm-1 and 596 cm-1 correspond to Eg and A1g modes of the rhombohedral phase and the one at 420 cm-1 represent the presence of monoclinic Li2MnO3 component. Microstructural evaluation by scanning electron microscopy and energy dispersive X-ray spectroscopy divulged the highly dense polyhedral-shaped agglomerates with respective elements. X-ray photoelectron spectroscopy analysis revealed 2+, 3+, and 4+ as the predominant oxidations of Ni, Co, and Mn respectively. Electrochemical measurements were performed using CR2032 type coin cells assembled with Li-metal foil as reference/counter electrode and spray-coated composite materials as cathode. Extended rate capability tests were also carried out at different C-rates, C/40, C/20, C/10, C/5, and 1C and compared performances of the three compositions. The results indicate that the composite cathode with x = 0.5 exhibited better electrochemical performances in terms of high discharge capacity (~250 mAh/g) , rate capability and cycleability in comparison with those with x = 0.3 and 0.7. According to the electrochemical studies, the first cycle charge profile was quite different from the subsequent cycles and irreversible capacity losses are much higher in the first cycle. The voltage in the cell increases monotonically until 4.45 V and reaches a plateau region between 4.45 and 4.6 V. To understand the local structural changes occurring in the materials and investigate the mechanisms associated with the first cycle charge-discharge profile, in situ Raman spectroscopy studies were conducted using specially designed/fabricated coin cells. Electrochemical properties of the composite cathode materials probed by charge-discharge profiles, cyclic voltammetry, cycleabilty, rate capabilty, electrochemical impedance spectroscopy and in situ Raman spectroscopic studies will be presented. Acknowledgements The financial support from NASA-URC grant #NNX10AQ17A is gratefully acknowledged. A part of the work was carried out at Jet Propulsion Laboratory under NASA’s Space Power Systems Program.

Photocatalytical nanocomposites: a review.

This review focuses on photocatalytically active nanocomposites that are based on the photoactive nanoparticles, or nanostructured particles captured on the surface of the different powderized carriers. Nanosized and nanostructured oxides and sulfides with selected metal cations (Ti, Zn, Cd, Fe, etc.) are intensively studied as the photocatalysts for different purposes. The nanodimension of these particles brings several disadvantages, among them being the negative impact on human health, which is a widely discussed topic nowadays. The nanoparticles can permeate through living tissue and enter living cells and thus a strong effort focused on diminishing this problem is the subject of research activities by many groups. One possible way to achieve control of the nanoparticles' mobility is capturing them on the surface of suitable particulate carriers with dimensions on the order of tenths and hundredths of microns whereas this approach leads to formation of new composite material. Clay minerals, silicates, carbonaceous materials, and other particulate matter are intensively studied for these purposes and proper selection of the substrate can bring additional functionality to the final composite. Very often the photoactivity, antibacterial properties, electrical conductivity, and other properties are significantly enhanced in the case of this kind of composite materials. Strong adhesion between the nanoparticles and the surface of the selected substrate is essential for the stability of the final composites. Characterization of the adhesion energies using laboratory experiments is quite difficult and molecular modeling can bring valuable information about the character of interactions at the interface of nanoparticles and substrate.

ChemInform Abstract: Developing Polymer Composite Materials: Carbon Nanotubes or Graphene?

AbstractReview: 133 refs.

Preparation and characterization of multiwalled carbon nanotube/WO3composite materials

Multiwalled carbon nanotube (MWCNT)/tungsten trioxide (WO3) composites were prepared by two different impregnation methods. Tungsten (VI) chloride (WCl6) was chosen as precursor compound to cover the surface of MWCNTs using either a simple or a combined impregnation technique. The applied mass ratio of MWCNT:WO3 was 1:15 for each sample. Two different temperatures (450 and 700 °C) were applied during the calcination process depending on the type of the synthesis method. The produced composite materials and the reference WO3 sample were characterized by transmission and scanning electron microscopies, Raman microscopy, and X-ray diffraction. The results show that using varying both solvents and methods has a significant effect on the formation of composite materials. As prepared MWCNT-based composites are planned to be applied in gas sensing techniques or in photocatalytic processes in the near future.

Aqueous electrophoretic deposition as a method for producing an investment casting shell mould ceramic face-coat. Part 1: formation of a carbon-filled investment casting wax electrode material

Aqueous electrophoretic deposition (EPD), using a zircon, i.e., zirconium silicate (ZrSiO4) suspension, has been investigated as an alternative to the conventional slurry dip-coating process for producing the face-coat of investment casting ceramic shell moulds. This is because EPD has the potential to (a) increase dimensional tolerances in the resultant casting, and (b) form a uniform face-coat on the entire mould-surface of complex shell moulds, including the small and/or complex cavities that are a problem for conventional dip-coating. Part 1 of this work addresses the formation of carbon-filled investment casting wax composite electrode materials. A carbon black powder and a micronised graphite powder were used as the alternative fillers in a water-emulsified pattern wax, an unfilled pattern wax and an unfilled runner wax. The runner wax composites exhibited consistently higher resistivities for both filler types and across the range of filler concentrations. Electrical resistivities of 1200 and 240 Ω cm were attained for the 16 vol% micronised graphite-filled and carbon black-filled straight pattern wax composites, respectively. The higher conductivity values associated with the use of carbon black filler are attributed to its high-surface area and hierarchical agglomerated structure. Rheologically, the micronised graphite-filled runner wax and water-emulsified pattern wax composites followed the Krieger–Dougherty model, which is helpful given that investment casting waxes are invariably injection moulded. In summary, these results confirm, in conjunction with Part 2, the feasibility of developing EPD as a promising technique for forming the investment casting shell mould ceramic face-coat.

The Preparation of Metallic Joinings to Optimise their Topography

Abstract Modern light structures increasingly require different alloys or metals to be joined with one another in the form of composite materials [1]. As a result of their different melting temperatures or of the formation of brittle inter-metallic phases, many combinations of metals cannot be produced using thermal methods. One alternative, however, is the use of solid state welding such as explosive or magnetic impulse welding [2; 3]. The examination and analysis of the bonding interfaces is therefore of central importance in the evaluation of the quality of the bond produced. Scanning electron microscopy together with electron probe micro­analysis of the characteristic X-rays emitted using EDX and WDX techniques can reveal information regarding the distribution of the metals present within the bonding interface [4], the presence of inter-metallic phases [5] and of areas of inadequate bonding. For an accurate evaluation of the characteristic X-rays produced, however, the surface of the specimen must be guaranteed to be both flat and smooth in order to prevent the effects of shadowing and deflection of the primary beam which might otherwise cause erroneous results in the elements present and their distribution [6]. A specimen surface which is not perfectly flat also makes it difficult to focus the electron beam. The simultaneous flat and smooth preparation of metallic composites which have very different strength and hardness properties is very difficult due to the different rates of removal of material during grinding and polishing [7; 8]. In view of this, the following methods of preparation used to produce flat and smooth specimen surfaces on two types of metallic joinings are presented.

Developing Polymer Composite Materials: Carbon Nanotubes or Graphene?

The formation of composite materials represents an efficient route to improve the performances of polymers and expand their application scopes. Due to the unique structure and remarkable mechanical, electrical, thermal, optical and catalytic properties, carbon nanotube and graphene have been mostly studied as a second phase to produce high performance polymer composites. Although carbon nanotube and graphene share some advantages in both structure and property, they are also different in many aspects including synthesis of composite material, control in composite structure and interaction with polymer molecule. The resulting composite materials are distinguished in property to meet different applications. This review article mainly describes the preparation, structure, property and application of the two families of composite materials with an emphasis on the difference between them. Some general and effective strategies are summarized for the development of polymer composite materials based on carbon nanotube and graphene.

Hybrid and biohybrid layered double hydroxides for electrochemical analysis

Layered double hydroxides (LDH) are lamellar materials that have been extensively used as electrode modifiers. Nanostructured organic-inorganic materials can be designed by intercalation of organic or metallic complexes within the interlayer space of these materials or by the formation of composite materials based on biopolymers (alginate or chitosan) or biomolecules, such as enzymes. These hybrid or biohybrid materials have interesting properties applicable in electroanalytical devices. From an exhaustive review of the literature, the relevance of these hybrid and biohybrid LDH materials as electrode materials for electrochemical detection of species with an environmental or health impact is evaluated. The analytical characteristics (sensitivity and detection limit) of LDH-based amperometric sensors or biosensors are scrutinized.

In situ generation of conducting polymer in a redox-active metal–organic gel

Metal–organic gels (MOGs) are evolving as a new class of stimuli-responsive materials. A redox-active MOG comprised of a ferric ion and benzene tricarboxylic acid ligand was prepared and characterized. In situ incorporation (without the use of any extraneous oxidant) of conducting polypyrrole and polythiophene moieties into the xerogel matrix was achieved, and thereby resulted in the formation of hybrid composite materials.

Macroscopic disruption of the continuity and stratified character of flow of structurized dispersions in shear flow

In this paper, concepts of the anisotropic nature of the flow of structured dispersions accompanied by disruption of a structure under continuous shear in layers oriented in the direction of shear flow are developed. The mechanism for the appearance and evolution of alternating solid and liquid fluid layers, together with disruption of the structure for cluster aggregates of particles of the dispersed phase, is shown experimentally, theoretically, and by computer simulation. The observed phenomena and those described in this paper significantly affect both the conditions for determination and description of rheological properties of structured dispersions and the technology of their production, processing, and formation of dispersed composite materials on their basis.