Showing papers on "Nanocomposite published in 2008"
TL;DR: In this article, the effects of particle size, particle/matrix interface adhesion and particle loading on the stiffness, strength and toughness of such particulate polymer composites are reviewed.
Abstract: There have been a number of review papers on layered silicate and carbon nanotube reinforced polymer nanocomposites, in which the fillers have high aspect ratios. Particulate–polymer nanocomposites containing fillers with small aspect ratios are also an important class of polymer composites. However, they have been apparently overlooked. Thus, in this paper, detailed discussions on the effects of particle size, particle/matrix interface adhesion and particle loading on the stiffness, strength and toughness of such particulate–polymer composites are reviewed. To develop high performance particulate composites, it is necessary to have some basic understanding of the stiffening, strengthening and toughening mechanisms of these composites. A critical evaluation of published experimental results in comparison with theoretical models is given.
2,767 citations
TL;DR: In this article, a general approach for the preparation of graphene−metal particle nanocomposites in a water−ethylene glycol system using graphene oxide as a precursor and metal nanoparticles (Au, Pt and Pd) as building blocks.
Abstract: Graphene sheets, which possess unique nanostructure and a variety of fascinating properties, can be considered as promising nanoscale building blocks of new composites, for example, a support material for the dispersion of nanoparticles. Here, we present a general approach for the preparation of graphene−metal particle nanocomposites in a water−ethylene glycol system using graphene oxide as a precursor and metal nanoparticles (Au, Pt and Pd) as building blocks. These metal nanoparticles are adsorbed on graphene oxide sheets and play a pivotal role in catalytic reduction of graphene oxide with ethylene glycol, leading to the formation of graphene−metal particle nanocomposites. The typical methanol oxidation of graphene−Pt composites in cyclic voltammograms analyses indicated its potential application in direct methanol fuel cells, bringing graphene−particle nanocomposites close to real technological applications.
1,478 citations
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01 Jan 2008
TL;DR: In this article, the authors present an analysis of the Elastic and Thermal properties of a fiber-reinforced Lamina with respect to the properties of the Fibers and Matrix in a Lamina.
Abstract: Introduction Definition General Characteristics Applications Material Selection Materials Fibers Matrix Thermoset Matrix Thermoplastic Matrix Fiber Surface Treatments Fillers and Other Additives Incorporation of Fibers into Matrix Fiber Content, Density and Void Content Mechanics Fiber-Matrix Interaction in a Unidirectional Lamina Characteristics of a Fiber-Reinforced Lamina Laminated Structure Interlaminar Stresses Performance Static Mechanical Properties Fatigue Properties Impact Properties Other Properties Environmental Effects Long-Term Properties Fracture Behavior and Damage Tolerance Manufacturing Fundamentals Bag Molding Process Compression Molding Pultrusion Filament Winding Resin Transfer Molding Other Manufacturing Processes Manufacturing Processes for Thermoplastic Matrix Composites Quality Inspection Methods Design Failure Predictions Laminate Design Considerations Joint Design Design Examples Applications Examples Metal and Ceramic Matrix Composites Metal Matrix Composites Ceramic Matrix Composites Carbon-Carbon Composites Nanocomposites Nanoclay Carbon Nanofiber Carbon Nanotubes Appendices Woven Fabric Terminology Residual Stresses in Fibers and Matrix in a Lamina Due to Cooling Alternative Equations for the Elastic and Thermal Properties of a Lamina Halpin-Tsai Equations Typical Mechanical Properties of Unidirectional Continuous Fiber Composites Properties of Various SMC Composites Typical Mechanical Properties of Metal Matrix Composites Determination of Design Allowables Useful references Index
1,254 citations
TL;DR: Zhang et al. as mentioned in this paper designed a new approach to synthesize tin nanoparticles encapsulated elastic hollow carbon spheres (TNHCs) with uniform size, in which multiple tin particles with a diameter of less than 100 nm were encapsulated in one thin hollow carbon sphere with a thickness of only about 20 nm, thus leading to both the content of Sn up to over 70% by weight and the void volume in carbon shell as high as about 70-80%by volume.
Abstract: Lithium batteries, as a main power source or back-up power source for mobile communication devices, portable electronic devices and the like, have attracted much attention in the scientific and industrial fields due to their high electromotive force andhigh energy density. Tomeet the demand for batteries having higher energy density and improved cycle characteristics, in recent years, a great deal of attempt has been made to develop new electrode materials or design new structures of electrode materials. For anode materials, among them, some elementary substances such as silicon (Si), germanium (Ge), or tin (Sn) provide promising alternative to conventional carbonaceous anode active materials, because they are capable of alloying with more lithium and thus leading to the extreme high initial capacity density. For example, metallic tin has recently been widely concerned as one of the promising anode materials for lithium batteries due to the following reasons. Firstly, its theoretical specific capacity (Li4.4Sn, 992mAhg ) ismuchhigher than that of conventional graphite (LiC6, 372 mA h g ). Secondly, the tin anode has higher operating voltage than graphite, so it is less reactive and the safety of batteries during rapid charge/discharge cycle could be improved. Furthermore, a significant advantage of metallic tin over graphite is that it does not encounter solvent intercalationwhich causes irreversible charge losses at all. Unfortunately, the biggest challenge for employing metallic tin as applicable active anode materials is that it is suffering from huge volume variation during Liþ insertion/extraction cycle, which leads to pulverization of the electrode and very rapid capacity decay. Without appropriate structure design, the tin electrode typically fails after only a few discharge/charge cycles. It is therefore very desirable to design a new tinbased materials mainly composed of metallic tin with high specific capacity as well as good cycle performance. Some metal/oxides and carbon nanocomposites have been reported with high capacity and capacity retention when used as anodematerials, because the carbon shell has itself good electronic conductivity and prevents the aggregation of active materials, and especially thin carbon shell has good elasticity to effectively accommodate the strain of volume change during Liþ insertion/extraction. Very recently, tin-encapsulated spherical hollow carbon was synthesized by the pyrolysis of tin-containing organic precursors have exhibited higher capacity and better cycle performance than unencapsulated mixture materials, in which the content of tin active substance was only 24 wt%. Nanostructured tin dispersed in a carbonmatrix and carbon-encapsulated hollow tin nanopartides were also reported as superior anode materials. These studies showed that both coating tin nanomaterials with carbon layer and dispersing tin nanoparticles in carbon matrix are effective to improve their electrochemical properties in lithium ion batteries. It is obvious that thehigher content of and smaller size of tin, as well as the thinner carbon coating will greatly contribute to the further enhancement of material performance since the lithium storage density in tin ismuch higher than that in carbon. Meanwhile, this tin-based anode material has to be designed to own enough void volume to compensate the volume expansion during Liþ insertion, which is important to improve its cycle performance. In the presentwork,we therefore designed anewapproach to synthesize tin nanoparticles encapsulated elastic hollow carbon spheres (TNHCs) with uniform size, in which multiple tin nanoparticles with a diameter of less than 100 nm were encapsulated inone thin hollow carbon spherewith a thickness of only about 20 nm, thus leading to both the content of Sn up to over 70% by weight and the void volume in carbon shell as high as about 70–80%by volume. This void volume and the elasticity of thin carbon spherical shell efficiently accommodate the volume change of tin nanoparticles due to theLi-Sn alloying-dealloying reactions, and thus prevent the pulverization of electrode. As a result, this type of tin-based nanocomposites have very high specific capacity of >800 mA h g 1 in the initial 10 cycles, and >550mAh g 1 after the 100th cycle, as well as excellent cycling [*] Prof. L.-J. Wan, W.-M. Zhang, Dr. J.-S. Hu, Prof. Y.-G. Guo, S.-F. Zheng, L.-S. Zhong, Prof. W.-G. Song Beijing National Laboratory for Molecular Sciences Institute of Chemistry Chinese Academy of Sciences (CAS) Beijing 100080 (P.R. China) E-mail: wanlijun@iccas.ac.cn
1,000 citations
TL;DR: It is shown that layered hybrid films combining high tensile strength and ductile behavior can be obtained through the bottom-up colloidal assembly of strong submicrometer-thick ceramic platelets within a ductile polymer matrix.
Abstract: Although strong and stiff human-made composites have long been developed, the microstructure of today's most advanced composites has yet to achieve the order and sophisticated hierarchy of hybrid materials built up by living organisms in nature. Clay-based nanocomposites with layered structure can reach notable stiffness and strength, but these properties are usually not accompanied by the ductility and flaw tolerance found in the structures generated by natural hybrid materials. By using principles found in natural composites, we showed that layered hybrid films combining high tensile strength and ductile behavior can be obtained through the bottom-up colloidal assembly of strong submicrometer-thick ceramic platelets within a ductile polymer matrix.
943 citations
TL;DR: In this article, the synthesis and characterization of nanosized zinc oxide particles and their application on cotton and wool fabrics for UV shielding were reported, and the effectiveness of the treatment was assessed through UV-Vis spectrophotometry and the calculation of the ultraviolet protection factor (UPF).
Abstract: We report the synthesis and characterization of nanosized zinc oxide particles and their application on cotton and wool fabrics for UV shielding. The nanoparticles were produced in different conditions of temperature (90 or 150 °C) and reacting medium (water or 1,2-ethanediol). A high temperature was necessary to obtain small monodispersed particles. Fourier transformed infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray powder diffractometry (XRD) were used to characterize the nanoparticles composition, their shape, size and crystallinity. The specific surface area of the dry powders was also determined. ZnO nanoparticles were then applied to cotton and wool samples to impart sunscreen activity to the treated textiles. The effectiveness of the treatment was assessed through UV–Vis spectrophotometry and the calculation of the ultraviolet protection factor (UPF). Physical tests (tensile strength and elongation) were performed on the fabrics before and after the treatment with ZnO nanoparticles.
823 citations
TL;DR: In this article, a strain sensor was fabricated from a polymer nanocomposite with multiwalled carbon nanotube (MWNT) fillers, and the authors investigated the piezoresistivity of this strain sensor based on an improved three-dimensional (3D) statistical resistor network model incorporating the tunneling effect between the neighboring CNTs, and a fiber reorientation model.
793 citations
01 Aug 2008
TL;DR: In this paper, a strain sensor was fabricated from a polymer nanocomposite with multiwalled carbon nanotube (MWNT) fillers, and the piezoresistivity of the sensor was investigated based on an improved three-dimensional (3D) statistical resistor network.
Abstract: A strain sensor has been fabricated from a polymer nanocomposite with multiwalled carbon nanotube (MWNT) fillers. The piezoresistivity
of this nanocomposite strain sensor has been investigated based on an improved three-dimensional (3D) statistical resistor network
model incorporating the tunneling effect between the neighboring carbon nanotubes (CNTs), and a fiber reorientation model. The
numerical results agree very well with the experimental measurements. As compared with traditional strain gauges, much higher sensitivity
can be obtained in the nanocomposite sensors when the volume fraction of CNT is close to the percolation threshold. For a small
CNT volume fraction, weak nonlinear piezoresistivity is observed both experimentally and from numerical simulation. The tunneling
effect is considered to be the principal mechanism of the sensor under small strains.
685 citations
TL;DR: In this paper, the reinforcing potential of cellulose nanofibers obtained from agro-residues was investigated in a starch-based thermoplastic polymer, and the results showed that the tensile strength and modulus of the nanocomposite films revealed significantly enhanced properties compared to the pure thermoplastics.
599 citations
TL;DR: In this paper, the dielectric properties of epoxy nanocomposites with insulating nano-fillers, viz., TiO2, ZnO and AI2O3 were investigated at low filler concentrations by weight.
Abstract: The dielectric properties of epoxy nanocomposites with insulating nano-fillers, viz., TiO2, ZnO and AI2O3 were investigated at low filler concentrations by weight. Epoxy nanocomposite samples with a good dispersion of nanoparticles in the epoxy matrix were prepared and experiments were performed to measure the dielectric permittivity and tan delta (400 Hz-1 MHz), dc volume resistivity and ac dielectric strength. At very low nanoparticle loadings, results demonstrate some interesting dielectric behaviors for nanocomposites and some of the electrical properties are found to be unique and advantageous for use in several existing and potential electrical systems. The nanocomposite dielectric properties are analyzed in detail with respect to different experimental parameters like frequency (for permittivity/tan delta), filler size, filler concentration and filler permittivity. In addition, epoxy microcomposites for the same systems were synthesized and their dielectric properties were compared to the results already obtained for nanocomposites. The interesting dielectric characteristics for epoxy based nanodielectric systems are attributed to the large volume fraction of interfaces in the bulk of the material and the ensuing interactions between the charged nanoparticle surface and the epoxy chains.
566 citations
TL;DR: Results from the self-assembly of block copolymers with ligand-stabilized platinum nanoparticles, leading to lamellar CCM-Pt-4 and inverse hexagonal hybrid mesostructures with high nanoparticle loadings are presented.
Abstract: The synthesis of ordered mesoporous metal composites and ordered mesoporous metals is a challenge because metals have high surface energies that favor low surface areas. We present results from the self-assembly of block copolymers with ligand-stabilized platinum nanoparticles, leading to lamellar CCM-Pt-4 and inverse hexagonal (CCM-Pt-6) hybrid mesostructures with high nanoparticle loadings. Pyrolysis of the CCM-Pt-6 hybrid produces an ordered mesoporous platinum-carbon nanocomposite with open and large pores (>/=10 nanometers). Removal of the carbon leads to ordered porous platinum mesostructures. The platinum-carbon nanocomposite has very high electrical conductivity (400 siemens per centimeter) for an ordered mesoporous material fabricated from block copolymer self-assembly.
TL;DR: In this article, the effects of chemical states of Ag on the photoelectrochemical properties of Ag−TiO2 composites were investigated with Ag(0)− TiO2 and Ag(I)−SiO2 prepared by photoreductionthermal treatment (PRT) method.
Abstract: The effects of chemical states of Ag on the photoelectrochemical (PEC) properties of Ag−TiO2 composites were investigated with Ag(0)−TiO2 and Ag(I)−TiO2 prepared by photoreduction-thermal treatment (PRT) method. The comparison of photoaction spectra of Ag(0)−TiO2 and Ag(I)−TiO2 showed that only the Ag(0) containing samples had notable photocurrent under visible light (in the range of 400−800 nm), which was attributed to the highly dispersed Ag(0), according to the DRS, XRD and XPS measurements. During the photocurrent spectra measurements of Ag(0)−TiO2, it was demonstrated that Ag(0) was photoexcited because of plasma resonance in the visible light region, and charge separation was accomplished by the transport of photoexcited electrons from Ag(0) to the TiO2 conduction band with the simultaneous formation of Ag(I), which could be partially reduced to the initial active Ag(0) state under the following UV light irradiation. Actually, it was the interconversion of Ag(0) and Ag(I) during the alternating irra...
TL;DR: The LBL assembly technique for introducing metallic NPs into polymers in order to generate a material with combined optomechanical properties is described, and how the expanded use of NWs and carbon nanotubes in nanocomposite materials holds promise in the design of conductive films and new nanoscale devices.
Abstract: New assembly techniques are required for creating advanced materials with enough structural flexibility to be tuned for specific applications, and to be practical, the techniques must be implemented at relatively low cost. Layer-by-layer (LBL) assembly is a simple, versatile, and significantly inexpensive approach by which nanocomponents of different groups can be combined to coat both macroscopically flat and non-planar (e.g., colloidal core-shell particles) surfaces. Compared with other available assembly methods, LBL assembly is simpler and more universal and allows more precise thickness control at the nanoscale. LBL can be used to combine a wide variety of species--including nanoparticles (NPs), nanosheets, and nanowires (NWs)--with polymers, thus merging the properties of each type of material. This versatility has led to recent exceptional growth in the use of LBL-generated nanocomposites. This Account will focus on the materials and biological applications of introducing inorganic nanocrystals into polymer thin films. Combining inorganic NPs and NWs with organic polymers allows researchers to manipulate the unique properties in the nanomaterial. We describe the LBL assembly technique for introducing metallic NPs into polymers in order to generate a material with combined optomechanical properties. Similarly, LBL assembly of highly luminescent semiconductor NPs like HgTe or CdTe with poly(diallyldimethylammonium chloride) (PDDA) was used to create uniform optical-quality coatings made on optical fibers and tube interiors. In addition, LBL assembly with inorganic nanosheets or clay molecules is reported for fabricating films with strong mechanical and ion transport properties, and the technique can also be employed to prepare Au/TiO(2) core/sheath NWs. The LBL approach not only will be useful for assembly of inorganic nanocrystals with various polymers but can be further applied to introduce specific functions. We discuss how the expanded use of NWs and carbon nanotubes (CNTs) in nanocomposite materials holds promise in the design of conductive films and new nanoscale devices (e.g., thin-film transistors). New photonic materials, sensors, and amplifiers can be constructed using multilayer films of NPs and can enable fabrication of hybrid devices. On the biological side, inorganic nanoshells were used as assembly tools with the goal of detecting neurotransmitters (specifically, dopamine) directly inside brain cells. In addition, the stability of different cell lines was tested for fabricating biocompatible films using LBL. NP LBL assembly was also used for homogeneous and competitive fluorescence quenching immunoassay studies for biotin and anti-biotin immunoglobulin molecules. Finally, introduction of biomolecules with inorganic NPs for creating biocompatible surfaces could also lead to new directions in the field of biomedical applications.
TL;DR: Glycerol-plasticized starch/clay nanocomposites films were prepared from potato starch and three different loadings of montmorillonite aqueous suspensions by casting, to study the effect of the nanoclay in the properties of starch as discussed by the authors.
TL;DR: A review of polymer assisted fabrication of inorganic and organic nanoparticles with controlled shape, size, and functional properties is presented in this article, focusing on the physical and chemical aspects of the problem.
TL;DR: This development should lead to the design of catalysts with superior performance that take advantage of nanoparticles high surface-to-volume ratio and their shape-dependent surfacestructure.
Abstract: The development of more efficient and stable catalysts hasbeen an increasingly important goal for chemists andmaterials scientists for both economic and environmentalreasons. Much attention has been paid recently to nano-particlesoftransitionmetals,particularlynoblemetals,asaresult of significant progress in synthetic methods forcontrollingtheircomposition,size,andshape.Thisdevelop-ment should lead to the design of catalysts with superiorperformance that take advantage of nanoparticles highsurface-to-volume ratio and their shape-dependent surfacestructure.
TL;DR: In this paper, a hybrid composite architecture of carbon nanotubes (CNTs), advanced fibers and a matrix is described, from CNT synthesis and characterization through to standard mechanical and electrical laminate tests.
TL;DR: In this paper, a colloidal aqueous suspension of cellulose whiskers was used as filler to obtain tensile properties of polyvinyl alcohol (PVA) nanocomposite materials.
TL;DR: In this paper, the covalent binding of chitosan (CTS) onto the surface of magnetic Fe3O4 nanoparticles which were prepared by hydrothermal method using H2O2 as an oxidizer.
TL;DR: In this paper, a nonionic surfactant Triton X-100 was applied to enhance the dispersion of carbon nanotubes (CNTs) in polymer and the properties of nanocomposite.
Abstract: Surfactant has been successfully applied to enhance the dispersion of carbon nanotubes (CNTs) in polymer and the properties of nanocomposite. CNTs were treated with a nonionic surfactant Triton X-100, and its effects on dispersion state, surface chemistry, structure and morphology of CNTs, as well as on the thermomechanical, mechanical and electrical properties of CNT/epoxy nanocomposites were evaluated. The mechanical properties such as impact fracture toughness, flexural strength and modulus, the thermomechanical properties, as well as the electrical conductivity of the nanocomposite all showed significant improvements after the treatment. The above observations are attributed to the “bridging” effects between the CNT and epoxy, which are introduced by the hydrophobic and hydrophilic segments of the nonionic surfactant. The enhanced interfacial interactions gave rise to improved dispersion and wetting of CNTs in polymer matrix, enhancing the mechanical and fracture properties of the nanocomposite. Unlike chemical functionalization techniques, however, the surfactant treatment exhibited little adverse effect on electrical conducting behavior of the nanocomposite.
TL;DR: In this article, the role of aggregation and interfacial thermal resistance on the effective thermal conductivity of nanofluids and nanocomposites was analyzed, and it was shown that the thermal conductivities can be significantly enhanced by the aggregation of nanoparticles into clusters.
TL;DR: The GOx/CH-Fe(3)O(4)/ITO nanocomposite bioelectrode has response time of 5s, linearity as 10-400 mgdL(-1) of glucose, sensitivity as 9.3 microA/(mgdLcm(2)) and shelf life of about 8 weeks under refrigerated conditions.
TL;DR: In this paper, a polyamide (PA) nanocomposite membrane containing high loading of TiO2 nanoparticles synthesized via in-situ interfacial polymerization was reported.
TL;DR: It is shown that electrical conductivity can be dramatically increased by creating a network of CNTs in the composite, while the thermal conductivity and thermopower remain relatively insensitive to the filler concentration.
Abstract: Segregated-network carbon nanotube (CNT)-polymer composites were prepared, and their thermoelectric properties were measured as a function of CNT concentration at room temperature. This study shows that electrical conductivity can be dramatically increased by creating a network of CNTs in the composite, while the thermal conductivity and thermopower remain relatively insensitive to the filler concentration. This behavior results from thermally disconnected, but electrically connected, junctions in the nanotube network, which makes it feasible to tune the properties in favor of a higher thermoelectric figure of merit. With a CNT concentration of 20 wt %, these composites exhibit an electrical conductivity of 4800 S/m, thermal conductivity of 0.34 W/m x K and a thermoelectric figure of merit (ZT) greater than 0.006 at room temperature. This study suggests that polymeric thermoelectrics are possible and provides the basis for further development of lightweight, low-cost, and nontoxic polymer composites for thermoelectric applications in the future.
TL;DR: In this paper, three different industrially available multiwalled carbon nanotube (MWNT) materials were directly incorporated into polycarbonate by melt mixing using a small-scale compounder.
TL;DR: In this paper, a functionalized graphene sheet (FGS)/silicone porous nanocomposite was reported to have great stability and heat dissipation efficiency, highlighting their potential in applications with intense thermal requirements.
Abstract: In this article we report the successful manufacture of a novel functionalized graphene sheet (FGS)/silicone porous nanocomposite. Both the cellular microstructure and the properties of the porous nanocomposite were investigated in detail. The thermal properties show great stability and heat dissipation efficiency, highlighting their potential in applications with intense thermal requirements. Additionally, compression measurements indicate that there was a favourable interaction between the graphene nanosheets and the polymer.
TL;DR: In this article, the effects of nano-SiC addition on the thermoelectric and mechanical properties of high-density n-type Bi 2 Te 3 materials were studied.
TL;DR: Compared to unmodified nanoparticles, the grafting of PCL chains on the surface results in lower modulus values but significantly higher strain at break, which clearly reflects the originality of the reinforcing phenomenon of polysaccharide nanocrystals resulting from the formation of a percolating network thanks to chain entanglements and cocrystallization.
TL;DR: In this paper, surface-functionalized BaTiO3 nanoparticles and ferroelectric polymers were used to obtain an energy density of 7 J/cm3 in a nanocomposite containing 30 vol % BaO3 at 150 MV/m.
Abstract: Polymer nanocomposites were prepared using surface-functionalized BaTiO3 nanoparticles and ferroelectric polymers. The nanocomposites based on the polymer with a higher permittivity exhibit larger electric displacements under the applied fields, thereby leading to higher energy densities. An energy density of 7 J/cm3 has been achieved in a nanocomposite containing 30 vol % BaTiO3 at 150 MV/m, representing an impressive ∼120% enhancement in comparison with that in the neat polymer.
TL;DR: In this paper, the authors developed conductive, carbon nanotube (CNT)-filled, polymer composite films that can be used as strain sensors with tailored sensitivity and measured resistivities were correlated with the applied strains to evaluate the sensitivity of the nanocomposite film sensor.
Abstract: This paper reports the development of conductive, carbon nanotube (CNT)-filled, polymer composite films that can be used as strain sensors with tailored sensitivity. The films were fabricated via either melt processing or solution casting of poly(methyl methacrylate) (PMMA) matrices containing low concentrations of multi-walled carbon nanotubes (MWNTs). The electrical resistivities of the films were measured in situ using laboratory-designed fixtures and data acquisition system. The measured resistivities were correlated with the applied strains to evaluate the sensitivity of the nanocomposite film sensor. The study suggests that conductive network formation, thus strain sensitivity of the conductive films, can be tailored by controlling nanotube loading, degree of nanotube dispersion, and film fabrication process. The developed sensors exhibited a broad range of sensitivity, the upper limit showing nearly an order of magnitude increase compared to conventional, resistance-type strain gages. A semi-empirical model that shows the relationship between CNT volume fraction and sensitivity is proposed.