bluuebunny/crossref_metadata_2025_split huggingface dataset:
Characterizing the Thermomechanical Degradation of a Filled Elastomer by Morphology and X Ray Photoelectron Spectroscopy
Authors: Crosta Giovanni F , Nelson Art J , Camatini Marina C 
Published: April 2011

ABSTRACTThree types of debris particles, denoted by L2, H2 and K3 respectively, originated from the abrasion of silica-filled, vulcanized rubber under different test conditions (severity) were analyzed and compared. The structural fractal dimension, DFS, of the particle perimeter was chosen as a morphological descriptor (but not necessarily as an intrinsic property of the fractured material !). Said dimension was estimated by processing light microscopy images. A value of the morphological threshold, TST, which separates the textural from the structural domain in the RICHARDSON plot was determined in order to maximize discrimination between the three particle types and rank them by increasing values of DFS. Particles from the highest severity test (K3) exhibited the highest value of DFS. X ray photoelectron spectroscopy (XPS) provided elemental composition, core level binding energies and the speciation of C, N, O, Si and S. As a result, L2 debris was found to originate from two processes: fracture of rubber and segregation of extender oil. Evidence has come both from morphology and XPS. Particles of H2 and K3 were ascribed to fracture alone. Comparison between K3 and the reference material, rasped rubber (RAS), shows the following: a) increase of the [S]/[C] surface atomic concentration ratio from RAS to K3; b) existence of multiple bonding states of S in K3 with energy peaking at 162.9 ± 0.3 eV ([-S-S-]n); c) weak contribution of R-S-O-R oxidized S species in K3 at 165 eV, not seen in RAS; d) no evidence of either SO3 or SO4 groups in any material. Although preliminary, these results prove the ability of morphological analysis and XPS to characterize the surface properties of debris particles non destructively.
Monotonic and Cyclic Fatigue Behavior of a High Performance Ceramic Fiber
Authors: Kerr M. , Williams J.J. , Chawla N. , Chawla K.K. 
Published: April 2011

ABSTRACTMonotonic and cyclic fatigue behavior of fibers are of general interest, regardless of the end use of the product whether in a composite or in a fabric. Study of cyclic fatigue behavior of fibers is particularly difficult because of their small diameter (∼10 μm) and high aspect ratio. In this paper, we report some preliminary results of monotonic tension and tension – tension fatigue behavior of a ceramic fiber: Nextel 312 (Al2O3-SiO2-B2O3) fiber. This fiber has a nanocrystalline structure with B2O3mostly in the form of a glassy phase. The tensile strength data of this fiber showed a Weibull modulus of 4.6, indicating a large degree of variability. Our experiments show clear indication of cyclic loading being more damaging than static loading for Nextel 312. The fracture surface observations of fatigues samples showed some distinctly different features from those observed in fibers subjected to monotonic tension.
Novel Templated Polyphenol for Ionic Conductivity
Authors: Bruno Ferdinando F. , Nagarajan Ramaswamy , Kumar Jayant , Samuelson Lynne A. 
Published: April 2011

ABSTRACTPhenolic polymers and phenol formaldehyde resins are of great interest for a number of electronic and industrial applications. Unfortunately, the toxic nature of the starting materials (formaldehyde) and harsh reaction conditions required for the synthesis of these polymers have severely limited their use in today’s markets. We present here an alternative, biocatalytic approach where the enzyme horseradish peroxidase is used to polymerize phenol in the presence of a template such as polyethylene oxide. Here the template serves as a surfactant that can both emulsify the phenol and polyphenol chains during polymerization and maintain water/solvent solubility of the final polyphenol/template complex. The reactants and the reaction conditions of this approach are mild and result in high molecular weight, electrically and optically active, water-soluble complexes of polyphenol and the template used. High molecular weight water-soluble polyphenol/polyethylene oxide complexes were formed. The ionic conductivity and potential use of these polymers as polyelectrolytes for battery and solution cell applications will be discussed.
Insights into Toughening Particulate Brittle Composites
Authors: Merchant I.J. , Chandler H.W. , Henderson R.J. , Stebbings T. , Macphee D.E. 
Published: April 2011

ABSTRACTA conventional approach to the toughening of brittle materials has been to incorporate fibrous inclusions. These toughen the composite by acting as crack bridges, with energy being dissipated by frictional losses during pull-out of the fibre or by matrix failure on the scale of fibre surface roughness. In all cases, toughening has been achieved only where propagating macrocracks have interacted with an appreciable number of reinforcing inclusions. This paper considers the probability that toughening via crack-bridging in these fibrous and especially particulate toughened materials has not been optimised and proposes the idea that the frequency of interaction between crack and inclusion is strongly increased by un-bonding the inclusion from the matrix. Results from studies on cement-mortars are presented in support of this and show significant improvements in toughness associated with samples in which inclusions are deliberately un-bonded from the matrix in advance of the crack arriving.
Infiltration of Al-Mg Alloy into SiC Preform in the Production of Metal Matrix Composites by Pressureless Infiltration
Authors: Zulfia A. , Hand R.J. 
Published: April 2011

ABSTRACTMolten Al-Mg alloys has been infiltrated into SiC to produce Al matrix composites at 900oC for different infiltration times under N2. The wettability of the ceramic reinforcement by the Al-Mg alloy is crucial in determining whether Al can be infiltrated into ceramic preform. Sessile drop results showed that Al alloys with Mg contents greater than 8wt-% had a contact angle lower than 90o, after 5 minutes contact time, this was associated with the infiltration of Al-Mg alloys into SiC preform occurred after 30 minutes. Sessile drop experiments also show that SiC is similarly wetted by Al-Mg alloys under N2. It is concluded that the infiltration process does not involve the intermediate nitride phase suggested by other authors. These materials were also charaterised both mechanical properties and microstructure.
The Coercivity – Remanence Tradeoff in Nanocrystalline Permanent Magnets
Authors: Lewis Laura H. , Crew David C. 
Published: April 2011

ABSTRACTThe energy product (BH)maxis a figure of merit quantifying the maximum amount of useful work that can be performed by the magnet. The energy product is determined by the magnetic remanence and the coercivity which, as extrinsic properties, are determined by the magnets' microstructure. Thus, in principle, magnetic material microstructures may be tailored to obtain defined parameters to produce optimal permanent magnets. However, as asserted by the eponymous Murphy, “Nature favors the hidden flaw”. While there is still much undeveloped potential in nanomagnetic materials, with relevant length scales on the order of 100 Å, accumulating evidence strongly suggests that maximum remanence and maximum coercivity are mutually exclusive in nanocrystalline magnetic materials. Diverse experimental and computational results obtained from nanocrystalline Nd2Fe14B-based magnets produced by melt-spinning techniques and subjected to various degrees of thermomechanical deformation confirm this conclusion. Recent results obtained from temperature-dependent magnetic measurement, magnetic force microscopy and simple micromagnetic modeling will be reviewed and summarized. The results, while somewhat discouraging, do hint at possible materials design routes to sidestep the inherent performance limitations of the magnetic nanostructures.
Silver-Polyimide Nanocomposite Films Yielding Highly Reflective Surfaces
Authors: Southward Robin E. , Dean C. J. , Scott J. L. , Broadwater S. T. , Thompson D. W. 
Published: April 2011

ABSTRACTHighly reflective surface-metallized flexible polyimide films have been prepared by the incorporation of the soluble silver ion complex (1,1,1-trifluoroacetylacetonato)silver(I) into dimethylacetamide solutions of the poly(amic acid) prepared from 2,2-bis(3,4-dicarboxyphenyl)-hexafluoropropane dianhydride (6FDA) and 2,2-bis[4-(4-aminophenoxy)phenyl]hexafluoro-propane (4-BDAF). Thermal curing of solution cast silver(I)-poly(amic acid) films leads to cycloimidization of the amic acid with concommitant silver(I) reduction and formation of a reflective surface-silvered film at 8 and 13 weight percent silver. The metallized films are thermally stable and flexible with mechanical properties similar to those of the parent polyimide. TEM reveals that the bulk (interior) of the polyimide composite films have 5-20 nanometer-sized silver particles with a surface layer of silver metal ca. 80 nm thick. Neither the bulk nor the surface of the films is electrically conductive. Adhesion of the surface metal to polyimide is excellent.
What Xe Nanocrystals in Al Can Teach us in Materials Science
Authors: Allen C. W. , Birtcher R. C. , Dahmen U. , Furuya K. , Song M. , Donnelly S. E. 
Published: April 2011

ABSTRACTNoble gases are generally very insoluble in solids. For example, Xe implanted into Al at 300 K forms a fine dispersion of crystalline precipitates and, at large enough fluence, fluid precipitates, both of which are stabilized, relative to the gas phase, by the Laplace pressure due to precipitate/matrix interface tensions. High resolution electron microscopy has been performed to determine the largest Xe nanocrystalline precipitate in local equilibrium with fluid Xe precipitates within the Al matrix. From the shape and size of the largest crystal and the Laplace pressure associated with its interface, we show that the interface tensions can be derived by setting the Laplace pressure equal to the pressure for solid/fluid Xe equilibrium derived from bulk Xe compression isotherms at the temperature of equilibration and observation. The Xe/Al interface tensions thus derived are in the range of accepted values of surface tensions for the Al matrix. Furthermore, it is suggested that this same technique may be employed to estimate unknown surface tensions of a solid matrix from the size and shape of maximal nanocrystals of a noble gas element, which have been equilibrated in that matrix at the temperature of observation.
H3PO4 / oxide nanoparticles / polymer composites as proton conducting membranes
Authors: Carrière D. , Barboux P. , Moreau M. , Boilot J.-P. 
Published: April 2011

ABSTRACTStable sols of 60 nm colloidal zirconia have been prepared by thermolysis of zirconium acetate. The surface complexing acetate groups have been replaced by phosphoric acid groups. Phosphate grafting has been characterized by dynamic light scattering, infrared spectroscopy, 31P nuclear magnetic resonance and impedance spectroscopy measurements. These systems give acid and proton conductive particles (4.10-5 S.cm-1 at 70 % relative humidity).H3PO4/ZrO2/PVDF-co-HFP composite membranes have been synthesized. Impedance spectroscopy measurements allow discrimination between proton conduction at the surface of the phosphated particles and within free H3PO4 in the polymer. For the highest H3PO4/ZrO2 ratios, the latter phenomenon prevails, giving a proton conductivity of 6.10-4 S.cm-1 at 70 % R.H.
Doping and Electrochemical Capacitance of Carbon Nanotube-Polypyrrole Composite Films
Authors: Hughes Mark , Chen George Z. , Shaffer Milo S. P. , Fray Derek J. , Windle Alan H. 
Published: April 2011

ABSTRACTComposite films were electrochemically synthesised via the simultaneous deposition of multiwalled nanotubes and polypyrrole, a conducting polymer. Negatively charged functional groups attached to the surface of the acid treated nanotubes enables the tubes to act as a dopant for the PPy in these films. Scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy revealed that the nano-porous three-dimensional arrangement of PPy coated MWNTs in these films produced specific capacitances per mass and geometric area as high as 192 F g-1 and 1.0 F cm-2, respectively. This value of specific capacitance per geometric area exceeds that of both component materials and other carbon nanotube-conducting polymer composites. The composite films described in this report were also able to charge and discharge more than an order of magnitude faster than similarly prepared pure PPy films. The nano-porosity and small diffusion distances within the composite films, crucial to achieving the superior capacitive performance, were found to be dependent on the concentration of nanotubes and additional dopant anions in the polymerisation electrolyte, offering possibilities for tailoring of the composite structure.
Nano-Cylinder Structure Studied by X-ray Diffraction
Authors: Xu Gu , Feng Zhechuan , Popovic Zoran , Lin Jianyi , Vittal Jagadese. J. 
Published: April 2011

ABSTRACTThe study of nano-cylinder structure has attracted much attention due to the application of multi-wall carbon nanotubes (MWCNTs). While some TEM observations indicate that they are formed by seamless concentric cylinders, other TEM and high pressure X-ray diffraction studies suggest that they look like scrolls of graphite sheets. Although many people now accept the concentric cylinder model, there has been no confirmation reported. On the other hand, this structural difference of MWCNTs plays a crucial role in determining the properties and suitability for future applications. For example, the periodical boundary condition can only be imposed for cylinders, but not for scrolls. To resolve this issue, we employed high-resolution X-ray diffraction to measure detailed profiles of the Bragg peaks for high-purity MWCNTs. We then identified some unusual observations unique to the nano-cylinder structure, followed by the analysis of the structural difference in the Fourier transform between nanotubes formed by scrolls and concentric cylinders. The simulation results are then compared with the experimental data to reveal the structural details.
A Non-Traditional Vapor-Liquid-Solid Method for Bulk Synthesis of Semiconductor Nanowires
Authors: Sharma Shashank , Sunkara Mahendra K. , Lian Guoda , Dickey Elizabeth C. 
Published: April 2011

ABSTRACTMultiple silicon nanowires were synthesized using large gallium pools and microwave plasma. Results showed that nanowires growing out of different sized large gallium drops show little variation in diameters, suggesting that our non-traditional technique can be used to synthesize bulk amounts of monodispersed nanowires out of thin films of molten gallium.
Optical, Electrical and Microstructural Properties of Tin Doped Indium Oxide Films made from Sintered Nanoparticles
Authors: Hultåker Annette , Hoel Anders , Granqvist Claes-Göran , Doorn Arie van , Jongerius Michel J. , Burgard Detlef 
Published: April 2011

ABSTRACTThin transparent and electrically conductive films of tin doped indium oxide (ITO) were made by sintering of nanoparticle dispersions. The resistivity decreased to 1–10-2 μcm upon treatment at 800°C, while the luminous transmittance remained high. The property evolution was connected with sintering and densification as studied by Scanning Electron Microscopy, X-ray Diffraction, X-ray Fluorescence and Elastic Recoil Detection Analysis.
Grain-Size-Dependent Thermal Transport Properties in Nanocrystalline Yttria-Stabilized Zirconia
Authors: Yang Ho-Soon , Eastman J.A. , Thompson L.J. , Bai G.-R. 
Published: April 2011

ABSTRACTUnderstanding the role of grain boundaries in controlling heat flow is critical to the success of many envisioned applications of nanocrystalline materials. This study focuses on the effect of grain boundaries on thermal transport behavior in nanocrystalline yttria-stabilized zirconia (YSZ) coatings prepared by metal-organic chemical vapor deposition.
Supersonic Nanocrystal Deposition for Nanostructured Materials
Authors: Nichols W.T. , O'Brien D.T. , Malyavanatham G. , Becker M.F. , Keto J.W. 
Published: April 2011

ABSTRACTWe experimentally demonstrate the large scale production and controlled collection of metal and semiconductor nanocrystals by laser ablation of microparticles entrained at high density in a flowing aerosol. For silver, produced nanocrystals exhibit bimodal, log-normal size distributions. Mean particle sizes are controlled from 3-16 nm by varying the type and pressure of carrier gas as well as laser fluence. For collection, a micronozzle orifice (d = 200 [.mu]m) accelerates nanocrystals through a sonic jet into a vacuum chamber for deposition onto a room temperature substrate. We describe two regimes of deposition that depend on the nanocrystal's energy per atom on impact. Soft landings ( E << 1 eV/ atom) preserve the individual particle properties such as size and shape. Low energy impaction is demonstrated for CdSe in an argon carrier gas. The CdSe nanoclusters remain crystalline upon deposition and display visible photoluminescence. At higher particle impaction velocities (E ∼ 0.3 eV/atom) nanocrystals exhibit the onset of self sintering upon impact. At high number densities, adherent, conductive lines are formed from deposited silver nanocrystals. Line widths of 33 [.mu]m FWHM are directly written onto substrates using a 200 [.mu]m diameter nozzle.
Processing Effects on The Morphology of Hydrothermally Derived Nanocrystalline Lead Titanate
Authors: Ye Zhiyuan , Slamovich Elliott B. , King Alexander H. 
Published: April 2011

ABSTRACTNanocrystalline lead titanate was synthesized by reacting nanocrystalline titanium oxide in aqueous solutions of potassium hydroxide and lead acetate at 200 degrees C. X-ray diffraction (XRD) and TEM studies suggest that the initial KOH concentration influenced the nucleation and growth behavior of the lead titanate nanoparticles. Powders were processed in aqueous solutions containing 0.10 M lead acetate and a Pb:Ti ratio of 1, with varying concentrations of KOH. Powders processed in 0.01 M KOH were composed of irregularly shaped particles with 50-100 nm in size, processing in 0.10 M KOH produced particles with finger-like morphology and broader particle size distribution, and processing in 1.0 M KOH resulted in anisometric plates with (001) facets, and 100-200 nm in size. XRD studies have shown systematic variations in the position and symmetry of reflections with a l component as a function of particle size. This indicates that the c/a ratio of lead titanate increases with decreasing nanoparticle size
Nanocomposite based on semiconductor oxides SnO2/WO3
Authors: Rumyntseva M.N. , Boulova M.N. , Chareev D.A. , Ryabova L.I. , Akimov B.A. , Gaskov A.M. 
Published: April 2011

ABSTRACTNanocrystalline SnO2 and WO3 and nanocomposite with Sn:W ratio 1:9, 1:1, 9:1 were prepared by co-precipitation of α-stannic and tungstic acids. Phase composition and average crystallite size were determined from XRD data. Presence of the second component results in the reduction of the crystallites growth rate, giving rise to the enhancement of thermal stability of nano-scaled system. TGA data allowed to estimate the concentration νH2O of water adsorbed on nanocomposite effective surface. Maximal νH2O value and the highest resistance were observed for nanocomposite with Sn:W = 1:1. The temperature dependence of resistance R reveals its activation character. The current-voltage curves are interpreted in terms of electrochemical capacitor recharge.
Dispersion of Functionalized Nanoclay Platelets in an Amine-Cured Epoxy Resin System
Authors: Raghavan D. , Feresenbet E. , Yebassa D. , Emekalam A. , Holmes G. 
Published: April 2011

ABSTRACTNanocomposites are a relatively new class of materials obtained by dispersing montmorillonite clay in a polymer matrix. Evidences from literature suggest that clay platelet dispersion during nanocomposite preparation and clay-matrix adhesion are major technical issues that need to be addressed in order to achieve the desired property enhancements in polymer-clay hybrid nanocomposites. We have studied the interaction of the organically functionalized clay with the epoxy resin by including along the chain structure functional groups that will facilitate interaction with the resin. Through conventional routes, functional molecules have been synthesized and deposited on to the clay surface. Both the functionalized and nonfunctionalized clay has been analyzed using thermal gravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). The exfoliation of nanoclay platelets in amine cured epoxy system has been studied using X-ray diffraction (XRD) and transmission electron microscopy (TEM).
Innovative And Cost-Effective Microfabrication Of Nanoceramic Components
Authors: Nair Balakrishnan G. 
Published: April 2011

ABSTRACTAn innovative and cost-effective processing technique has been developed at Ceramatec Inc for the microfabrication of ceramic components requiring very high dimensional tolerance. The materials system is a proprietary nanophase composition called CERCANAM (CERamatec CAstable NAno Material). Scanning electron microscopy revealed that CERCANAM components can be fabricated with dimensional tolerance as high as ± 2 [.proportional]m for surface features on the die that have dimensions about 1 mm. The process can also be modified to fabricate nanoporous ceramic components with very high surface areas. Components with retained surface areas as high as 67-82% of the starting powder were fabricated. The fabrication process does not involve a high-temperature sintering step, which eliminates the loss of surface area from high temperature sintering. It is anticipated that microcomponents fabricated with specific microstructures and properties will have applications in the optical fiber industry as interconnects, in the electronic packaging industry and the chemical industry.
3D Periodic Arrays of Nanoparticles Inside Mesoporous Silica Films
Authors: Besson Sophie , Gacoin Thierry , Jacquiod Catherine , Ricolleau Christian , Boilot Jean-Pierre 
Published: April 2011

AbstractCdS nanoparticles were grown inside a 3D hexagonal porous silica film. The film pore size and organization allowed the perfect control of particle repartition and size (3.5 nm), leading to a 3D nanocrystal array inside the silica matrix. The method was extended to another silica porous structure with larger pores, which allowed to obtain larger particles (5.8 nm). This process was then successfully generalized to other metal sulfides.
3D Highly Oriented Nanoparticulate and Microparticulate Array of Metal Oxide Materials
Authors: Vayssieres Lionel , Guo Jinghua , Nordgren Joseph 
Published: April 2011

AbstractAdvanced nano and micro particulate thin films of 3d transition and post-transition metal oxides consisting of nanorods and microrods with parallel and perpendicular orientation with respect to the substrate normal, have been successfully grown onto various substrates by heteronucleation, without template and/or surfactant, from the aqueous condensation of solution of metal salts or metal complexes (aqueous chemical growth). Three-dimensional arrays of iron oxide nanorods and zinc oxide nanorods with parallel and perpendicular orientation are presented as well as the oxygen K-edge polarization dependent x-ray absorption spectroscopy (XAS) study of anisotropic perpendicularly oriented microrod array of ZnO performed at synchrotron radiation source facility.