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Showing papers on "Composite number published in 2000"


Journal ArticleDOI
TL;DR: In this paper, in situ transmission electron microscopy studies provided information regarding composite deformation mechanisms and interfacial bonding between the multi-wall carbon nanotubes and polymer matrix, indicating significant load transfer across the nanotube-matrix interface.
Abstract: Multiwall carbon nanotubes have been dispersed homogeneously throughout polystyrene matrices by a simple solution-evaporation method without destroying the integrity of the nanotubes. Tensile tests on composite films show that 1 wt % nanotube additions result in 36%–42% and ∼25% increases in elastic modulus and break stress, respectively, indicating significant load transfer across the nanotube-matrix interface. In situ transmission electron microscopy studies provided information regarding composite deformation mechanisms and interfacial bonding between the multiwall nanotubes and polymer matrix.

2,431 citations


Journal ArticleDOI
TL;DR: In this article, a combination of solvent casting and melt mixing was used to disperse carbon nanotubes in poly(methyl methacrylate) (PMMA) composite films showed higher conductivity along the flow direction than perpendicular to it.

1,060 citations


Journal ArticleDOI
TL;DR: The most widely applied methods for the production of composite materials and composite parts are based on casting techniques such as the squeeze casting of porous ceramic preforms with liquid metal alloys and powder metallurgy methods.

836 citations


Journal ArticleDOI
TL;DR: In this paper, a composite structure study revealed a coexistence of exfoliated and intercalated MMT layers, especially for low and moderate silicate loadings, which promoted a new crystalline phase different than the one of the respective neat PVA, characterized by higher melting temperature and a different crystal structure.
Abstract: Poly(vinyl alcohol)/sodium montmorillonite nanocomposites of various compositions were created by casting from a polymer/silicate water suspension. The composite structure study revealed a coexistence of exfoliated and intercalated MMT layers, especially for low and moderate silicate loadings. The inorganic layers promote a new crystalline phase different than the one of the respective neat PVA, characterized by higher melting temperature and a different crystal structure. This new crystal phase reflects on the composite materials properties. Namely, the hybrid polymer/silicate systems have mechanical, thermal, and water vapor transmission properties, which are superior to that of the neat polymer and its conventionally filled composites. For example, for a 5 wt % MMT exfoliated composite, the softening temperature increases by 25 °C and the Young's modulus triples with a decrease of only 20% in toughness, whereas there is also a 60% reduction in the water permeability. Furthermore, due to the nanoscale d...

764 citations


Journal ArticleDOI
TL;DR: An attempt has been made to enhance the bonding strength of HA coating by forming a composite coating with Ti, and the obtained results revealed that the addition of Ti to HA improved the bonded strength of coating significantly.

334 citations


Journal ArticleDOI
TL;DR: In this paper, an empirical prediction model based on self-consistent theory is proposed to obtain precise prediction of effective dielectric constant of a polymer-ceramic composite for embedded capacitor application.
Abstract: Nanostructure polymer-ceramic composite with high dielectric constant (/spl epsiv//sub /spl tau///spl sim/90) has been developed for embedded capacitor application. This polymer-ceramic system consists of lead magnesium niobate-lead titanate (PMN-PT) ceramic particle and modified high-dielectric constant low-viscosity epoxy resin. In order to obtain precise prediction of effective dielectric constant of this composite, an empirical prediction model based on self-consistent theory is proposed. The electrical polarization mechanism and interaction between epoxy resin and ceramic filler has been studied. This model can establish the relevant constitutional parameters of polymer-ceramic composite materials such as particle shape, composition, and connectivity that determine the dielectric properties of the composite. This model is simpler, uses fewer parameters and its prediction compares better with experiment (error <10%). The precision and simplicity of the model can be exploited for predictions of the properties and design of nanostructure ferroelectric polymer-ceramic composites. The effective-medium theory (EMT) has been proved a good tool to predict effective properties of nanocomposites.

290 citations


Journal ArticleDOI
S.S Morye1, Peter Hine1, R.A. Duckett1, Debra J. Carr, I. M. Ward1 
TL;DR: In this paper, the authors developed a simple model for calculating the energy absorption by polymer composites upon ballistic impact, where three major components were identified as contributing to the energy lost by the projectile during ballistic impact.

287 citations


Journal ArticleDOI
TL;DR: In this article, tossa jute fibres were treated with corona discharge and ultraviolet (UV) to improve the mechanical properties of natural-fibre/epoxy composites.

281 citations


Journal ArticleDOI
TL;DR: In this paper, a carbon nanotube-Co-MgO composite powder is prepared by reducing a Mg0.9Co0.1O solid solution in H2-CH4 atmosphere.
Abstract: A carbon nanotube–Co–MgO composite powder is prepared by reducing a Mg0.9Co0.1O solid solution in H2–CH4 atmosphere. The oxide matrix and part of the Co catalyst are dissolved by acid treatment without damage to the nanotubes. More than 80% of the carbon nanotubes have either one or two walls. The diameters of the nanotubes are in the range 0.5–5 nm. The utilized method may be a real improvement in the low-cost, large-scale synthesis of single- and double-walled carbon nanotubes.

251 citations


Patent
06 Mar 2000
TL;DR: A tubular intraluminal prosthesis includes a PTFE or ePTFE tubular structure such as a graft, and a tubular diametrically deformable stent circumferentially surrounding the tubular structures.
Abstract: A tubular intraluminal prosthesis includes a PTFE or ePTFE tubular structure such as a graft, and a tubular diametrically deformable stent circumferentially surrounding the tubular structure. The diametrically deformable stent includes a polymeric coating which allows for attachment to the tubular graft structure and enhances the biocompatibility and integrity of the composite prosthesis.

239 citations


Journal ArticleDOI
TL;DR: In this paper, the quasi-static and impact properties of a novel fiber/metal laminate system based on a tough glass-fibre-reinforced polypropylene (GFPP) are investigated.

01 Jan 2000
TL;DR: In this paper, a ZrB2-SiC composite was prepared from a mixture of zirconium, silicon, and B4C via reactive hot pressing, and the microstructure of the composite was observed via scanning electron microscopy.
Abstract: A ZrB2‐SiC composite was prepared from a mixture of zirconium, silicon, and B4C via reactive hot pressing. The three-point bending strength was 506 6 43 MPa, and the fracture toughness was 4.0 MPazm 1/2 . The microstructure of the composite was observed via scanning electron microscopy; the in-situ-formed ZrB2 and SiC were found in agglomerates with a size that was in the particle-size ranges of the zirconium and silicon starting powders, respectively. A model of the microstructure formation mechanism of the composite was proposed, to explain the features of the phase distributions. It is considered that, in the reactive hot-pressing process, the B and C atoms in B4C will diffuse into the Zr and Si sites and form ZrB2 and SiC in situ, respectively. Because the diffusion of Zr and Si atoms is slow, the microstructure (phase distributions) of the obtained composite shows the features of the zirconium and silicon starting powders.

Journal ArticleDOI
TL;DR: In this article, a starch-graft-polyacrylamide/clay superabsorbent composite is synthesized by graft copolymerization reaction of acrylamides, potato starch and clay mineral micropowder, followed by hydrolysis with sodium hydroxide.
Abstract: A novel starch-graft-polyacrylamide/clay superabsorbent composite is synthesized by graft copolymerization reaction of acrylamide, potato starch and clay mineral micropowder, followed by hydrolysis with sodium hydroxide. The water absorbency of the composite reaches 4000 g H 2 O/g. The influence of kind and amounts of clay and of the crosslinker in the composite on the absorbent properties is discussed in this paper.

Journal ArticleDOI
15 Dec 2000-Polymer
TL;DR: In this article, the phase structure of ternary polypropylene/elastomer/calcium carbonate composites has been investigated using scanning electron microscopy, dynamic mechanical analysis and differential scanning calorimetry.

Patent
29 Feb 2000
TL;DR: In this article, a method of manufacturing a multilayer, composite footwear upper having a three-dimensional geometry is described, which includes the steps of forming a substantially planar composite sheet from two or more layers (10), heating the composite sheet (12), and compression molding the composite sheets into the 3D geometry of the footwear upper (14).
Abstract: A method of manufacturing a multi-layer, composite footwear upper(70) having a three-dimensional geometry includes the steps of forming a substantially planar composite sheet from two or more layers (10), heating the composite sheet (12), and compression molding the composite sheet into the three-dimensional geometry of the footwear upper (14). The composite sheet (70) is formed by laminating a first layer (20) of thermoplastic foam to a second layer (22) of thermoplastic urethane (TPU), preferably in the form of a TPU film. A third layer (24) of mesh fabric can be interposed between the first (20) and second (22) layers. The composite sheet (70) is compressed after heating in a mold cavity (62) to achieve the desired three-dimensional geometry. The composite sheet (70) can be compression molded into separate sections (172, 174, 176) which are assembled after molding to form the footwear upper (170). Alternatively, the composite sheet (70) can be compression molded into a seamless, unitary footwear upper (270) that requires minimal, if any, assembly for completion.

Journal ArticleDOI
TL;DR: In this paper, a Monte Carlo procedure was employed to generate periodic computer models with unit cells comprising of random dispersion of a hundred non-overlapping parallel fibers of different diameter.

Journal ArticleDOI
TL;DR: In this paper, the spectral density function of resonances is determined and its behavior is analyzed at different values of a parameter specifying the composite topology, which is not reduced to the Bruggeman topology but may be represented as a spheroid system.

Patent
20 Sep 2000
TL;DR: In this article, a three dimensional distribution of carbon nanotubes is described and a nonwoven network of randomly oriented fibers connected at their junctions to afford macropores in the spaces between the fibers.
Abstract: A composite is described having a three dimensional distribution of carbon nanotubes. The critical aspect of such composites is a nonwoven network of randomly oriented fibers connected at their junctions to afford macropores in the spaces between the fibers. A variety of fibers may be employed, including metallic fibers, and especially nickel fibers. The composite has quite desirable properties for cold field electron emission applications, such as a relatively low turn-on electric field, high electric field enhancement factors, and high current densities. The composites of this invention also show favorable properties for other an electrode applications. Several methods, which also have general application in carbon nanotube production, of preparing these composites are described and employ a liquid feedstock of oxyhydrocarbons as carbon nanotube precursors.

Journal ArticleDOI
TL;DR: In this article, the impact crushing behavior and energy absorption efficiency of glass/epoxy composite externally wrapped circular metal tubes have been studied and the predicted instantaneous velocity and displacement formulae are presented and compared with experimental results.

Patent
03 Aug 2000
TL;DR: Shaped, composite bodies are especially suitable for orthopaedic and other surgical use as mentioned in this paper, where one portion of the shaped bodies comprises an RPR-derived porous inorganic material, preferably a calcium phosphate.
Abstract: Shaped, composite bodies are provided. One portion of the shaped bodies comprises an RPR-derived porous inorganic material, preferably a calcium phosphate. Another portion of the composite bodies is a different solid material, preferably metal, glass, ceramic or polymeric. The shaped bodies are especially suitable for orthopaedic and other surgical use.

Journal ArticleDOI
TL;DR: In this article, the conductivity of mixed-phase composite electrolytes based on poly(ethylene oxide), lithium salts, and ferroelectric materials has been studied and the results showed that the combined addition of rutile type and assured long-term interfacial stability.
Abstract: The electrochemical properties of mixed‐phase composite electrolytes based on poly(ethylene oxide) (PEO), lithium salts , and ferroelectric materials have been studied. The ion‐conduction and lithium‐ion transference numbers of the composite polymer electrolytes were enhanced by the addition of these ferroelectric materials as a ceramic filler. The conductivity behavior of the composite electrolyte depended on the combination of lithium salt and the ferroelectric materials. The conductivity enhancement in the PEO‐LiX composite electrolytes with ferroelectric materials was rationalized by correlating the association tendency of anions with lithium cations and the spontaneous polarization of the ferroelectric ceramics due to their particular crystal structure. The combined addition of rutile type and assured long‐term interfacial stability. All the electrolytes studied here showed decomposition potentials higher than 4V vs. . © 2000 The Electrochemical Society. All rights reserved.

Patent
07 Dec 2000
TL;DR: In this article, a method of forming a composite of embedded nanofibers in a polymer matrix is disclosed, which includes incorporating a plurality of nanofiber that are embedded in polymer matrices in micron size fibers.
Abstract: A method of forming a composite of embedded nanofibers in a polymer matrix is disclosed. The method includes incorporating nanofibers in a plastic matrix forming agglomerates, and uniformly distributing the nanofibers by exposing the agglomerates to hydrodynamic stresses. The hydrodynamic said stresses force the agglomerates to break apart. In combination or additionally elongational flow is used to achieve small diameters and alignment. A nanofiber reinforced polymer composite system is disclosed. The system includes a plurality of nanofibers that are embedded in polymer matrices in micron size fibers. A method for producing nanotube continuous fibers is disclosed. Nanofibers are fibrils with diameters 100 nm, multiwall nanotubes, single wall nanotubes and their various functionalized and derivatized forms. The method includes mixing a nanofiber in a polymer; and inducing an orientation of the nanofibers that enables the nanofibers to be used to enhance mechanical, thermal and electrical properties. Orientation is induced by high shear mixing and elongational flow, singly or in combination. The polymer may be removed from said nanofibers, leaving micron size fibers of aligned nanofibers.

Journal ArticleDOI
Shengping Ruan1, Baokun Xu1, Hui Suo1, Fengqing Wu1, Siqing Xiang1, Muyu Zhao1 
TL;DR: ZnCo-substituted W-type barium hexagonal ferrite of the order of nanoscale is synthesized and investigated as microwave absorber in this article, based on a two-layer structure with the thickness of only 1 mm, a big reflection loss over broadband is obtained.

Journal ArticleDOI
TL;DR: In this article, the pore formation process of silica gel from tetraethoxysilane in the presence of citric acid (CA) was investigated and the average pore size successively increased from the micropore range to the mesopore range of ca. 10 nm with the increase in the CA content.
Abstract: The pore formation process of silica gel from tetraethoxysilane in the presence of citric acid (CA) was investigated. The silica gel prepared by pyrolysis of a composite of CA and silica had high specific surface area, ca. 1000 m2 g-1 and its pore volume increased linearly with increasing CA content. In addition, the average pore size successively increased from the micropore range to the mesopore range of ca. 10 nm with the increase in the CA content. The silica and the CA−silica composite were amorphous without long-range ordering. In the composite, amorphous CA and polymeric silica gel are mixed on a nanometer scale without the aid of specific chemical bonding, except for weak hydrogen bonding. Because of the nature of the composite, the silica gel network becomes rigid through the additional formation of Si−O−Si bonds during heating, irrespective of the existence of CA. Therefore, the bulky structure is retained without shrinkage after elimination of CA, and silica gel with high specific surface area ...

Journal ArticleDOI
TL;DR: In this paper, the effect of filler surface group on the conductivity, ion−ion, ion-polymer interactions, and microstructure of PEG−LiClO4−Al2O3 composite polymer electrolytes is studied.
Abstract: The effect of filler surface group on the conductivity, ion−ion, ion−polymer interactions, and microstructure of PEG−LiClO4−Al2O3 composite polymer electrolytes is studied. It is shown that the add...

Journal ArticleDOI
TL;DR: Fiber length, fiber volume fraction, and fiber strength were found to be key microstructural parameters that controlled the mechanical properties of CPC composites.
Abstract: A water-based calcium phosphate cement (CPC) has been used in a number of medical and dental procedures due to its excellent osteoconductivity and bone replacement capability. However, the low tensile strength of CPC prohibits its use in many unsupported defects and stress-bearing locations. Little investigation has been carried out on the fiber reinforcement of CPC. The aims of the present study, therefore, were to examine whether fibers would strengthen CPC, and to investigate the effects of fiber type, fiber length, and volume fraction. Four different fibers were used: aramid, carbon, E-glass, and polyglactin. Fiber length ranged from 3–200 mm, and fiber volume fraction ranged from 1.9–9.5%. The fibers were mixed with CPC paste and placed into molds of 3 × 4 × 25 mm. A flexural test was used to fracture the set specimens and to measure the ultimate strength, work-of-fracture, and elastic modulus. Scanning electron microscopy was used to examine specimen fracture surfaces. Fiber type had significant effects on composite properties. The composite ultimate strength in MPa (mean ± SD; n = 6) was (62 ± 16) for aramid, (59 ± 11) for carbon, (29 ± 8) for E-glass, and (24 ± 4) for polyglactin, with 5.7% volume fraction and 75 mm fiber length. In comparison, the strength of unreinforced CPC was (13 ± 3). Fiber length also played an important role. For composites containing 5.7% aramid fibers, the ultimate strength was (24 ± 3) for 3 mm fibers, (36 ± 13) for 8 mm fibers, (48 ± 14) for 25 mm fibers, and (62 ± 16) for 75 mm fibers. At 25 mm fiber length, the ultimate strength of CPC composite was found to be linearly proportional to fiber strength. In conclusion, a self-setting calcium phosphate cement was substantially strengthened via fiber reinforcement. Fiber length, fiber volume fraction, and fiber strength were found to be key microstructural parameters that controlled the mechanical properties of CPC composites. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 52, 107–114, 2000.

Patent
24 Apr 2000
TL;DR: In this paper, a two-part drill bit insert is made, consisting of a body portion of hard particles such as tungsten carbide particles mixed in an alloy binding the particles.
Abstract: This disclosure features a process of making a two part drill bit insert, namely, a body portion of hard particles such as tungsten carbide particles mixed in an alloy binding the particles. The alloy preferably comprises 6% cobalt with amounts up to about 10% permitted. The body is sintered into a solid member, and also joined to a PDC crown covering the end. The crown is essentially free of cobalt. The process sinters the crown and body while preserving the body and crown cobalt differences.

Journal ArticleDOI
TL;DR: In this article, the composite rods failed by localized adiabatic shear banding and exhibited self-sharpening behavior, and the composite rod performance was 10-20% better than tungsten heavy alloy penetrators of comparable aspect ratio.

Journal ArticleDOI
TL;DR: In this article, water-dispersible composites of polyaniline (PANI) and poly(N-vinylcarbazole) with nanodimensional ZrO2 were prepared.

Journal ArticleDOI
TL;DR: The MoS2/titanium composite (high titanium) self-lubricant (MoST™) was developed by Fox et al. as mentioned in this paper and has a coating hardness of 500 HV, a coefficient of friction of 0.02 during 100 N applied load reciprocating wear testing, and a low wear rate.
Abstract: As previously reported (Fox et al., Proc. PSE Conf., Garmisch Partenkirchen, 14–18 September, 1998), the properties of MoS2 coatings can be improved by the co-deposition of a small amount of titanium. These MoS2/Ti coatings, known as MoST™ produced by closed field unbalanced magnetron sputtering, are harder, much more wear resistant and less sensitive to atmospheric water vapour. These coatings have given excellent industrial results for a wide range of cutting and forming applications. Two forms of these MoS2/titanium composite coatings have been developed: MoS2/titanium composite (low titanium, 10 at%) and MoS2/titanium composite (high titanium, 20 at%). The MoS2/titanium composite (low titanium) exhibits a coating hardness of 500 HV, a coefficient of friction of 0.02 during 100 N applied load reciprocating wear testing, and a low wear rate, while the MoS2/titanium composite (high titanium) exhibits a coating hardness similar to that of TiN, a coefficient of friction of 0.04 during 100 N applied load reciprocating wear testing, and an extremely low wear rate. The choice of coatings is dependent upon the application. Recent industrial performance data related to the characteristics of these MoS2/titanium composite (high titanium) self-lubricant coatings, which are utilised now in large-scale production, are presented.