bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reduction of Moisture Sensitivity in Natural Fibres
Authors: Pott Gerard T. 
Published: April 2011

ABSTRACTWhen natural fibres are applied as reinforcement in polymer composites the moisture sensitivity, causing fibre swell and ultimately rotting through fungi attack, can be a very serious problem. A number of methods have been developed dealing with this problem that change the chemical and / or physical composition of the fibre, resulting in reduced moisture sensitivity. To this category belongacetylationandhydrothermaltreatment. For acetylation, acetic anhydride is used as a chemical that reacts with reactive OH-groups of the lignocellulose material, increasing hydrophobicity. In hydrothermal treatment no chemicals are used, only water and energy.The main focus of this paper is on hydrothermal treatment, the Duralin® process in particular, of bast fibres such as flax, jute and hemp. Acetylation is reviewed briefly. A survey is given of the structure and composition of bast fibres and the moisture adsorption and desorption mechanisms in these fibres.The Duralin® process involves three steps, hydrothermolysis, drying and curing. The raw material for the Duralin® process applied to flax is green rippled flax straw. This eliminates the need for the traditional dew-retting, a risky process where the freshly harvested flax stems lay on the field for about four weeks. The Duralin® process reduces moisture absorption and biological degradation, the fibre yield is higher than after dew-retting and the shives can be used as a filler material in polymers and for making a water proof particle board. The main causes for reduced water uptake after Duralin treatment will be reviewed.Duralin® fibres have equal or higher tensile strength and higher flexural modulus than fibres extracted from dew-retted flax. Compounds reinforced with these fibres have apart from decreased moisture sensitivity a better mechanical performance. Both the amount and the release rate of decomposition products resulting from compounding with polypropylene are significantly less for Duralin® fibres than for dew-retted or green fibres. Duralin® fibres are on a weight basis competitive with glass fibres.
Recent Advances in Oxide Glass Fiber Science
Authors: Lawton Ernest L. , Wallenberger Frederick T. , Li Hong 
Published: April 2011

ABSTRACTThe predominate substrate for multilayer printed wiring boards is laminate constructed from epoxy resin reinforced with fiber glass fabrics. This combination of materials dominates the segment of the electronics market where dimensional stability of the substrate is critical. The rapid development of high speed digital and analog electronic systems has challenged the predominance of fiber glass as the reinforcement of choice. As systems move to the GHz frequency range, there is a need for lower dielectric constant of the substrate to insure integrity and speed of signals. A lower dissipation factor of the substrate is desired for the wireless communication applications of printed wiring boards. A review is presented of materials competing as substrates for the high speed application of the printed wiring board market.
Continuous Carbon Nanofibers For Nanofiber Composites
Authors: Dzenis Yuris , Wen Yongkui 
Published: April 2011

ABSTRACTContinuous carbon nanofibers were manufactured using electrospinning technique. The as-spun polyacrylonitrile (PAN) nanofibers were stabilized and carbonized to convert them into carbon nanofibers. The diameters of typical carbon nanofibers were in the range from 100 -500 nanometers. Compared to the vapor grown carbon nanofibers, the electronspun carbon nanofibers were continuous, uniform in diameter, and solid. The electrospun nanofiber samples did not require purification. The carbon nanofibers were characterized by scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. Electron and X-ray diffraction patterns were obtained and analyzed. Nanocomposites of epoxy resin reinforced with as-spun PAN and carbon nanofibers were fabricated and analyzed. The results showed good potential of continuous carbon nanofibers for nanocomposite and other applications.
Carbon Nanofiber Treatment Effects On Composite Properties
Authors: Burton David J. , Glasgow D. Gerald , Kwag Choongyong , Lake Max L. 
Published: April 2011

ABSTRACTCarbon nanofibers (CNF) are vapor grown carbon fibers grown catalytically from gaseous hydrocarbons using metallic catalyst particles. While this type of carbon fiber has been known for many years, only recently have composite properties been studied. Rules for composite synthesis teach that composite properties depend on several key parameters, including fiber-matrix interphase and fiber aspect ratio. Good adhesion between these fibers and matrix resins is essential for the performance of CNF based composites, so the mechanical properties of composites are strongly influenced by fiber surface morphology and chemistry. This work examines the fiber-matrix adhesion problem as influenced by CNF fiber surface area and surface energy, and the impact of aspect ratio on composite electrical properties.
Design of Sandwich Composites with Multi-Functional Facesheets
Authors: Vaidya Uday K. , Pillay Selvum , Ricks Helena , Bartus Shane , Ulven Chad , Mathew Biju 
Published: April 2011

ABSTRACTSandwich composites find increasing use as flexural load bearing lightweight sub-elements in air / space vehicles, rail / ground transportation, marine and sporting goods. The core materials in these applications is usually balsa, foam or honeycombs, while laminated carbon or glass are used as facesheets. A limitation of traditional sandwich configurations is that the space in the core becomes inaccessible once the facesheets are bonded in place. Significant multi-functional benefits can be obtained by making either the facesheets or the core, space accessible. Multi-functionality is generally referred to as value added to the structure that enhances functions beyond traditional load bearing. Such functions may include sound / vibration damping, ability to route wires or embed sensors. The present work considers traditional core materials of nomex and aluminum honeycombs that possess functional space accessible facesheets, and their low velocity impact (LVI) response.
Spectroscopic Elucidation of Lanthanide Cation Dissolution Mechanism in Borosilicate Glass
Authors: Li Hong , Wang Zheming , Li Liyu , Strachan Denis M. , Su Yali. , Joly A.G. 
Published: April 2011

ABSTRACTOxides of lanthanide dissolution in a Na2O-Al2O3-B2O3-SiO2 glass using Gd as a probe was studied in detail using Raman, fluorescence, and phonon sideband (PSB) spectroscopic techniques. A mechanism of Gd cation dissolution, via partitioning, in the borate-rich and silicate-rich environments was confirmed by examining characteristics of the Raman band evolution, fluorescence emission and lifetime, and PSBs. The study concluded that i) Gd(III) cations in the borate-rich environment resembles Gd-metaborate local structure, i.e., 1BO4:1Gd:2BO3, ii) Gd cations partitioning in the borate-rich environment at low Gd2O3 concentration, [Gd2O3] -1/3[B2O3] < 0, and iii) excess Gd(III) cations, [Gd2O3]–1/3[B2O3], in the silicate-rich environment at high Gd2O3 concentration, [Gd2O3]–1/3[B2O3]>0.
Optimization of the In-Situ Al-Si Base Functionally Graded Material Fabricated by Centrifugal Casting
Authors: Oya-Seimiya Yoshihiro , Shinoda Tetsumori , Watanabe Yoshimi 
Published: April 2011

ABSTRACTThe fabricating conditions for the in-situ Al-Si base composite by the centrifugal casting method (CCM) have been examined. The crystallized Si particles with a lower density distribute in a gradient fashion as densely on the inner and thinly on the outer side of the wall of the cylindrical CCM-composite. Synthetically, the 25 mol% Si composite is recommended for the application like the engine liner.
Anhydride/Epoxy Functionalized Blends: Mechanical, Rheological and Thermal Properties
Authors: Bayram Goknur , Yilmazer Ulku 
Published: April 2011

ABSTRACTBlends of styrene-maleic anhydride (SMAH) and polyethylene-methyl acrylate-glycidyl methacrylate (E-MA-GMA) were produced in a batch mixer and in a corotating twin screw extruder. E-MA-GMA concentration was varied from 0 % to 50 %. Batch mixing indicated that the blend system was reactive. Extruded blends were characterized in terms of rheological, thermal and mechanical properties, and their morphology was observed. Rheological properties such as the storage modulus, loss modulus and complex viscosity exhibited maxima at 25 % EMA-GMA content. The blends had fine morphology as observed by scanning electron microscopy. Thermal properties were not significantly affected by the change in epoxy concentration. As E-MA-GMA concentration increased, tensile strength and modulus of elasticity decreased, but percent strain at break increased. These observations could be explained in terms of the chain extension / branching reactions that occurred in mixing the blends.
Processing, Dynamic Studies and Properties of Exfoliated Aerospace Epoxy-Organoclay Nanocomposites
Authors: Chen Chenggang , Curliss David 
Published: April 2011

ABSTRACTEpoxy nanocomposites were prepared from the montmorillonite after organic treatment with a high Tg epoxy resin (Shell Epon 862 and curing agent W). Investigation of the rheological characteristics showed that the addition of clay to the resin did not significantly alter the viscosity or cure kinetics and that the modified resin would still be suitable for liquid composite molding techniques such as resin transfer molding. DSC was performed to study the kinetics of the curing reactions in the modified resin. An in situ small-angle x-ray scattering (SAXS) experiment was used to try to understand the structural development during cure. Based on the in situ SAXS data, structural changes were monitored in real time during cure and analyzed. Results from wide-angle x-ray diffraction, SAXS, and transmission electron microscopy of the polymer-silicate nanocomposites were used to characterize the morphology of the layered silicate in the epoxy resin matrix. The glassy and rubbery moduli of the polymer-silicate nanocomposites were found to be greater than the unmodified resin due to the high aspect ratio and high stiffness of the layered silicate filler. The solvent absorption in methanol was also slower for the polymer-silicate nanocomposites.
Study of NiFe/SiO2 Nanocomposites
Authors: Hui S. , Zhang Y.D. , Xiao T. D. , Wu Mingzhong , Ge Shihui , Hines W. A. , Budnick J. I. , Yacaman M. J. , Troiani H. E. 
Published: April 2011

ABSTRACT(Ni75Fe25)v/(SiO2)1-v nanocomposites with v =0.5, 0.7, and 1.0, where 75 denotes the atomic percent of Ni in the Ni-Fe alloy phase and v denotes the volume fraction of the magnetic constituent in the composite, were synthesized using a wet chemical approach. The x-ray diffraction and TEM experiments show that the synthetic NiFe/SiO2 is a two-phase composite system in that an amorphous insulating SiO2 layer coats each Ni-Fe particle. The Ni-Fe particle is in a fcc Ni-Fe alloy state. Its size can be controlled over a rather large range between 5 nm to 70 nm by adjusting the reaction parameters. Particular attention was paid to reduce the chemical reaction temperature so as to insure the smallness of the particle size. Meanwhile, measurements of the saturation magnetization indicated that the higher the heat treatment temperature, the more complete the chemical reaction to form the Ni-Fe alloys from precursor materials.
Studies of Intersubband Transitions in Arrays of Bi Nanowire Samples Using Optical Transmission
Authors: Black M. R. , Maskaly K. R. , Rabin O. , Lin Y. M. , Cronin S. B. , Padi M. , Fink Y. , Dresselhaus M. S. 
Published: April 2011

ABSTRACTThis paper reports the fabrication of large diameter pores (> 150 nm) in anodic aumina that can be used to create wire arrays with significant surface effects, but without significant quantum confinement. These wires, therefore, allow us to distinguish between optica absorption spectra features originating from quantum effects and those from surface effects. The paper presents techniques towards fabricating these bismuth wire arrays, and presents optical absorption data from two bismuth nanowire arrays in the semimeta-semiconductor transition diameter regime. The results from previous publications are summarized and future directions are outlines.
Insertion of Inorganic-Biomolecular Nanohybrid into Eucaryotic Cell
Authors: Kwak Seo-Young , Hwang Sung-Ho , Jeong Yong-Joo , Park Jong-Sang , Choy Jin-Ho 
Published: April 2011

ABSTRACTIt has been clearly demonstrated that ATP could be intercalated into inorganic layered double hydroxide (LDH), giving rise to a biomolecular-inorganic nanohybrid with preserving its physico-chemical and biological integrity. It shows a remarkable transfer efficiency of ATP into target cells byalleviating anelectrical repulsion at the cell walls due to the neutralization of negative charge of phosphates by positive hydroxide layers. From cellular uptake experiment with laser scanning confocal fluorescence microscopy, it is revealed that the FITC-LDH hybrid is effectively transferred into 293 cells. Such an unique feature of biomolecule-LDH hybrid will open a new field of reserving and delivering genes, drugs and other functional biomolecules.
Catalyst-free Growth of Large Scale Ga2O3 Nanowires
Authors: Chang Ko-wei , Liu Sai-chang , Chen Liang-Yih , Hong Franklin Chau-Nan , Wu Jih-Jen 
Published: April 2011

ABSTRACTLarge scale of straight Ga2O3 nanowires is grown on a fused silica substrate by a simple catalyst-free CVD method using Ga metal and N2 / H2O reactants. The Ga2O3 nanowires with diameters ranging from 60 to 150 nm can be as long as several micrometers. XRD and TEM analyses indicate that the Ga2O3 nanowires exhibit a monoclinic structure. PL characteristic of the Ga2O3 nanowires shows a UV emission of 375 nm at room temperature.
Stress and Hardness of CrNx films
Authors: Janssen G.C.A.M. , Kamminga J.-D. , Sloof W.G.M. 
Published: April 2011

ABSTRACTChromium nitride films CrNx with x ranging form 0 to 1 were deposited by reactive PVD. Both stress and hardness in the films are a function of the composition. The growth stress and hardness for the majority of the films can be related through the Hall Petch relation. It is shown that the hardest films fall outside this relation. It is also shown that the hardest films are nanocrystalline. It is argued that the hardness of these films is a consequence of the nanocrystallinity of these films.
Nanostructured NiFe2O4 Soft Magnetic Ferrite
Authors: Zhang Zongtao , Zhang Y. D. , Xiao T. D. , Ge Shihui , Wu Mingzhong , Hines W. A. , Budnick J. I. , Gromek J. M. , Yacaman M. J. , Troiani H. E. 
Published: April 2011

ABSTRACTNiFe2O4 is an important high frequency soft magnetic material due to its ultra high resistivity; however, its initial permeability is rather low. Conventional magnetic ferrites are manufactured through ceramic processing. In an effort to explore innovative approaches for fabricating ferrite materials with improved performance, a study of fabricating nanostructured NiFe2O4 using wet chemical approaches has been carried out. The synthetic NiFe2O4 precursor was synthesized by a citrate reaction method followed by calcinating at various temperatures. Systematic studies concerning the crystallographic structure, the nanostructure and morphology of the particle, the phase homogeneity, the conditions for chemical reaction completion, and the magnetic properties have been carried out using x-ray diffraction, transmission electron microscopy, and magnetic measurements. The results show that by using a citrate reaction approach, pure phase and stoichiometric NiFe2O4 can be fabricated easily, and the particle size can be controlled on a nanometer scale, even at high calcination temperatures. In addition, a comparative study of the NiFe2O4 fabricated by conventional ceramic processing and this new citrate processing will be presented.
Dynamic Fracture Mechanisms in Nanostructured and Amorphous Silica Glasses Million-Atom Molecular Dynamics Simulations
Authors: Brutzel Laurent Van , Rountree Cindy L. , Kalia Rajiv K. , Nakano Aiichiro , Vashishta Priya 
Published: April 2011

ABSTRACTParallel molecular dynamics simulations are performed to investigate dynamic fracture in bulk and nanostructured silica glasses at room temperature and 1000 K. In bulk silica the crack front develops multiple branches and nanoscale pores open up ahead of the crack tip. Pores coalesce and then they merge with the advancing crack-front to cause cleavage fracture. The calculated fracture toughness is in good agreement with experiments. In nanostrucutred silica the crack-front meanders along intercluster boundaries, merging with nanoscale pores in these regions to cause intergranular fracture. The failure strain in nanostructured silica is significantly larger than in the bulk systems.
Sol-Gel Synthesis and Characterization of Neodymium-Ion Doped Nanostructured Titania Thin Films
Authors: Burns Andrew , Li W. , Baker C. , Shah S.I. 
Published: April 2011

ABSTRACTNd doped TiO2 nanostructured thin films were prepared by sol-gel technique on quartz and Si substrates using TiCl4 precursor. As-deposited amorphous films were annealed to form anatase phase in the thin films. The film grain size increased with annealing temperature. Above 800°C, rutile began to segregate and the grain size decreased slightly.The photodegradation of 2-chlorophenol (2-CP) was studied. Doping TiO2 with Nd+3 reduced the photodegradation time. The difference in the ionic radii of Nd+3 and Ti+4 and the oxygen affinities of Nd and Ti were responsible for this effect. These differences help promote electron trapping, thereby increasing the lifetime of the holes which are responsible for the oxidation of 2-CP.
Insight into the Formation of Ultrafine Nanostructures in Bulk Amorphous Zr54.5 Ti7.5Al10Cu20Ni8
Authors: Heinemann André , Hermann Helmut , Wiedenmann Albrecht , Mattern Norbert , Kühn Uta , Bauer Hans-Dietrich , Eckert Jürgen 
Published: April 2011

ABSTRACTBulk amorphous Zr54.5 Ti7.5Al10Cu20Ni8 is investigated by means of smal-angle neutron scattering (SANS), differential-scanning calorimetry (DSC), high-resolution electron microscopy (HREM) and other methods. The formation of ultrafine nanostructures in the glassy phase is observed and explained by a new model. Structura fluctuations of randomly distributed partialy ordered domains grow during annealing just below the glass transition temperature by local re-ordering. During anneaing the DSC gives evidence for a increasing volume fraction of the localy ordered domains. At high volume fractions of impinging domains a percolation threshold on the interconnected domain boundaries occurs and enhanced diffusion becomes possible. At that stage SANS measurements lead to satistically significant scattering data. The SANS signals are anayzed in terms of a model taking into account spherica particles surrounded by diffusion zones and interparticle interference effects. The mean radius of the nanocrystaline particles is determined to 1 nm and the mean thickness of the depletion zone is 2 nm. The upper limit for the volume fraction after annealing at 653 K for 4hours is about 20 %. Electron microscopy confirms the size and shows that the particle are crystaline.
Orientation of Aromatic Ion Exchange Diamines and the Effect on Melt Viscosity and Thermal Stability of PMR-15/ Silicate Nanocomposites
Authors: Campbell Sandi , Scheiman Daniel 
Published: April 2011

ABSTRACTNanocomposites of PMR-15 polyimide and a diamine modified silicate were prepared by addition of the silicate to the PMR-15 resin. The orientation of the ion exchange diamine within the silicate gallery was determined by x-ray diffraction and found to depend on the clay cation exchange capacity. The oligomer melt viscosity exhibited a dependence on the orientation of the diamine in the silicate interlayer, and in some cases, on the length of the diamine. A correlation was observed between the oligomer melt viscosity and the crosslinking enthalpy, where nanocomposites with an increased melt viscosity exhibited a decrease in enthalpy on crosslinking. After crosslinking, those nanocomposites with a high melt viscosity had poorer thermal oxidative stability compared to the less viscous systems. The melt viscosity was tailored by co-exchange of an aromatic diamine and an aliphatic amine into the silicate. Nanocomposites prepared with this silicate exhibited an increase in thermal oxidative stability compared to the neat resin.
Rapid-Solidification Effect on Magnetostriction in Iron-based Ferromagnetic Shape Memory Alloy
Authors: Furuya Yasubumi , Kubota Takeshi , Okazaki Teiko , Sato Mitsutaka , Wuttig Manfred 
Published: April 2011

ABSTRACTFe-29.6at%Pd ferromagnetic shape memory alloy (FSMA) ribbon formed by rapidly solidified, melt-spinning methods is expected to be useful as a new type of material which shows giant magnetostriction as well as quick response. The giant magnetostriction in the rolling direction depends strongly on applied magnetic-field direction and has a maximum value of 8×10-4 when the field is normal to the surface. This phenomenon is caused by the rearrangements of activated martensitic twin variants. The inverse phase transformation temperatures (As) obtained from Laser micrographs and magnetization vs. temperature curve are ∼307 K and 400∼440 K, respectively. We analyze magnetostriction, magnetic property and crystal structure of Fe-29.6at%Pd bulk sample before rapid solidification and the ribbon sample. From these results, it can be concluded that remarkable anisotropy of giant magnetostriction of ribbon sample is caused by the fine structure formed by the melt-spinning method. It may be possible to apply this method successfully to other FSMA and Ni2MnGa, which is difficult to manufacture owing to its brittleness.
Nanoscale compositional changes along fast ion tracks in equilibrium solid solutions: A computer simulation of ultra-fast solidification and thermomigration
Authors: Lopasso Edmundo M. , Caro Alfredo , Arregui Eduardo Ogando , Caro Magdalena 
Published: April 2011

ABSTRACTStarting from two equilibrium solid solutions in the Au-Ni system, we analyze the change in composition due to a 400 eV/Å fast ion track simulated by molecular dynamics in the Embedded Atom approximation. We aim at determining the influence of the thermodynamic forces derived from the large thermal gradients and the rapid solidification across the solidus and liquidus on the motion of solute atoms. One dimensional gradients as well as analytic models are used to quantitatively determine the domains of influence of these forces. Evidence shows that the liquidus and solidus equilibrium solidification predicted by the phase diagram is not reached during the track. The solute concentration is mainly determined by the combined diffusion and thermomigration mechanisms in the liquid stage.
Preparation of Optically Transparent Films of Poly(methyl methacrylate) (PMMA) and Montmorillonite
Authors: Vasiliu Elena , Wang Chyi-Shan , Vaia Richard A. 
Published: April 2011

ABSTRACTTransparent polymeric material with enhanced thermal, mechanical and barrier properties are of special interest for advanced structural, optical and photonic applications. The present paper reports a novel solution processing scheme for fabricating optically transparent polymer nanocomposites involving organophilic layered silicates. It is shown that the nanocomposite material prepared with PMMA and an organically modified montmorrilonite maintains the excellent optical transparency of PMMA. Small-angle x-ray scattering of the polymer nanocomposite material does not show any Bragg's reflection of the organophilic layered silicate. The optical transparency of the nanocomposite material is attributed to a high degree of exfoliation of the montmorrilonite in the polymer matrix.