Showing papers on "Nanocomposite published in 2011"
TL;DR: This Review assembles the current knowledge on the isolation of microfibrillated cellulose from wood and its application in nanocomposites; the preparation of nanocrystalline cellulose and its use as a reinforcing agent; and the biofabrication of bacterial nanocellulose, as well as its evaluation as a biomaterial for medical implants.
Abstract: Cellulose fibrils with widths in the nanometer range are nature-based materials with unique and potentially useful features. Most importantly, these novel nanocelluloses open up the strongly expanding fields of sustainable materials and nanocomposites, as well as medical and life-science devices, to the natural polymer cellulose. The nanodimensions of the structural elements result in a high surface area and hence the powerful interaction of these celluloses with surrounding species, such as water, organic and polymeric compounds, nanoparticles, and living cells. This Review assembles the current knowledge on the isolation of microfibrillated cellulose from wood and its application in nanocomposites; the preparation of nanocrystalline cellulose and its use as a reinforcing agent; and the biofabrication of bacterial nanocellulose, as well as its evaluation as a biomaterial for medical implants.
3,452 citations
TL;DR: In this article, the status of worldwide research in the thermal conductivity of carbon nanotubes and their polymer nanocomposites is reviewed, as well as the relationship between thermal conductivities and the micro- and nano-structure of the composites.
2,102 citations
TL;DR: In this article, the authors focus on graphite and describe its various modifications for use as modified fillers in polymer matrices for creating polymer-carbon nanocomposites, which is the basic building block of graphite.
1,092 citations
TL;DR: This work provides a promising methodology to fabricate tough and lightweight graphene-PMMA nanocomposite micro cellular foams with superior electrical and EMI shielding properties by simultaneously combining the functionality and reinforcement of the graphene sheets and the toughening effect of the microcellular cells.
Abstract: Functional polymethylmethacrylate (PMMA)/graphene nanocomposite microcellular foams were prepared by blending of PMMA with graphene sheets followed by foaming with subcritical CO2 as an environmentally benign foaming agent. The addition of graphene sheets endows the insulating PMMA foams with high electrical conductivity and improved electromagnetic interference (EMI) shielding efficiency with microwave absorption as the dominant EMI shielding mechanism. Interestingly, because of the presence of the numerous microcellular cells, the graphene−PMMA foam exhibits greatly improved ductility and tensile toughness compared to its bulk counterpart. This work provides a promising methodology to fabricate tough and lightweight graphene−PMMA nanocomposite microcellular foams with superior electrical and EMI shielding properties by simultaneously combining the functionality and reinforcement of the graphene sheets and the toughening effect of the microcellular cells.
954 citations
TL;DR: In this paper, the synthesis of polyhedral oligomeric silsesquioxane (T8-POSS) compounds, the miscibility of POSS derivatives and polymers, the preparation of both multifunctional and monofunctional monomers, and the applications of several high-performance POSS nanocomposites in such systems as light emitting diodes, liquid crystals, photo-resist materials, low-dielectric constant materials, self-assembled block copolymers, and nanoparticles.
886 citations
TL;DR: In this paper, the production, structure, properties and applications of cellulose nanowhiskers of rod-like structures have been discussed, and a wide range of chemical modifications have been described, including 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, polymerisation from the surface using Reversible Addition-Fragmentation chain Transfer (RAFT) and Atom Transfer Radical Polymerisation (ATRP), and rendering of the surface with cationic and anionic charge.
Abstract: This review covers the production, structure, properties and applications of nanowhiskers of cellulose. It is shown that these nanowhiskers can be generated, from various plant sources, with transverse dimensions as small as 3–30 nm, giving a high surface to volume ratio. Since the nanowhiskers are rod-like, it is shown how they can be self-assembled into chiral nematic liquid crystalline structures, not only in solution, but also in the dry state. The production of thin films of cellulose nanowhiskers, by spin coating and in combination with polymer electrolytes, is also covered. A wide range of chemical modification of cellulose nanowhiskers are reviewed; including 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, polymerisation from the surface using Reversible Addition–Fragmentation chain Transfer (RAFT) and Atom Transfer Radical Polymerisation (ATRP), and the rendering of the surface with cationic and anionic charge. The mechanical properties of cellulose nanowhiskers will also be covered, including the measurement of their stiffness using both Raman spectroscopy and Atomic Force Microscopy (AFM) measurements. The final part of the review will cover the applications and potential industrial use of cellulose nanowhiskers; namely for nanocomposite materials, thin films and other applications. Finally, some conclusions, including perspectives and future developments will be presented.
723 citations
TL;DR: In this paper, the surface modification of cellulose fibers by various methods is reviewed and the processing methods, properties, and various applications of nanocellulose and cellulosic composites are also discussed.
Abstract: Cellulose macro- and nanofibers have gained increasing attention due to the high strength and stiffness, biodegradability and renewability, and their production and application in development of composites. Application of cellulose nanofibers for the development of composites is a relatively new research area. Cellulose macro- and nanofibers can be used as reinforcement in composite materials because of enhanced mechanical, thermal, and biodegradation properties of composites. Cellulose fibers are hydrophilic in nature, so it becomes necessary to increase their surface roughness for the development of composites with enhanced properties. In the present paper, we have reviewed the surface modification of cellulose fibers by various methods. Processing methods, properties, and various applications of nanocellulose and cellulosic composites are also discussed in this paper.
685 citations
TL;DR: In this paper, a porous carbon nanofiber-sulfur (CNF-S) nanocomposites with various S loadings were synthesized via electrospinning, carbonization and solution-based chemical reactiondeposition method.
Abstract: Sulfur (S) encapsulated in porous carbon nanofibers (CNFs) was synthesized viaelectrospinning, carbonization and solution-based chemical reaction–deposition method. The chemical reaction–deposition strategy provides intimate contact between the S and the CNFs. This would not necessarily be the case for other reported methods, such as ball milling and thermal treatment. These novel porous carbon nanofiber–sulfur (CNF–S) nanocomposites with various S loadings showed high reversible capacity, good discharge capacity retention and enhanced rate capability when they were used as cathodes in rechargeable Li/S cells. We demonstrated here that an electrode prepared from a porous CNF–S nanocomposite with 42 wt% S maintains a stable discharge capacity of about 1400 mA h g−1 at 0.05 C, 1100 mA h g−1 at 0.1 C and 900 mA h g−1 at 0.2 C. We attribute the good electrochemical performance to the high electrical conductivity and the extremely high surface area of the CNFs that homogeneously disperse and immobilize S on their porous structures, alleviating the polysulfide shuttle phenomenon. SEM measurements showed that the porous CNF structures remained nearly unchanged even after 30 cycles' discharging/charging at 0.05 C.
558 citations
TL;DR: Thermodynamic study revealed that the adsorption process is endothermic and spontaneous in nature and the regenerated adsorbent can be reused successfully for two successive adsorptive-desorption cycles without appreciable loss of its original capacity.
522 citations
TL;DR: It is shown that nanocomposites based on the less defective solvent-exfoliated graphene exhibit a significantly larger enhancement in CO(2) photoreduction, especially under visible light.
Abstract: With its unique electronic and optical properties, graphene is proposed to functionalize and tailor titania photocatalysts for improved reactivity. The two major solution-based pathways for producing graphene, oxidation–reduction and solvent exfoliation, result in nanoplatelets with different defect densities. Herein, we show that nanocomposites based on the less defective solvent-exfoliated graphene exhibit a significantly larger enhancement in CO2 photoreduction, especially under visible light. This counterintuitive result is attributed to their superior electrical mobility, which facilitates the diffusion of photoexcited electrons to reactive sites.
511 citations
TL;DR: A magnetically separable ZnFe2O4-graphene nanocomposite photocatalyst with different graphene content was prepared by a facile one-step hydrothermal method as discussed by the authors.
Abstract: A magnetically separable ZnFe2O4–graphene nanocomposite photocatalyst with different graphene content was prepared by a facile one-step hydrothermal method. The graphene sheets in this nanocomposite photocatalyst are exfoliated and decorated with ZnFe2O4 nanocrystals. It was found that in the presence of H2O2, the photodegradation rate of methylene blue (MB) was 88% after visible light irradiation for only 5 min and reached up to 99% after irradiation for 90 min. In comparison with pure ZnFe2O4 catalyst, ZnFe2O4–graphene serves a dual function as the catalyst for photoelectrochemical degradation of MB and the generator of a strong oxidant hydroxyl radical (·OH) via photoelectrochemical decomposition of H2O2 under visible light irradiation. ZnFe2O4 nanoparticles themselves have a magnetic property, which makes the ZnFe2O4–graphene composite magnetically separable in a suspension system, and therefore it does not require additional magnetic components as is the usual case.
TL;DR: The state-of-the-art in the development of organic-inorganic nanocomposite PEMs for fuel cell applications can be classified into four categories: (i) doping inorganic proton conductors in PEM, (ii) nanocomposition by sol-gel method, (iii) covalently bonded inorganic segments with organic polymer chains, and (iv) acid-base PEM nan composites.
TL;DR: In this paper, two types of epoxy/GP nanocomposites with different interface strength using the combination of sonication and chemical modification were synthesized, and the surface modified graphene platelets (m -GP) formed clusters, showing a higher degree of dispersion and exfoliation of graphene.
TL;DR: In this study, only these chemically bonded CNTs/TiO(2) nanocomposites with appropriate loading amounts favor the separation of photogenerated electron-hole pairs and decrease their recombination rate and thus display significantly enhanced photocatalytic activity for degrading acetone in air under UV irradiation, as compared with pristine TiO( 2) counterparts and commercial P25 photocatalyst.
Abstract: Mesoporous multiwalled carbon nanotubes/titanium dioxide (CNTs/TiO2) nanocomposites with low loading amounts (0–0.5 wt%) of CNTs embedded inside mesoporous TiO2 aggregates has been prepared by a simple one-pot hydrothermal method using titanium sulfate as titanium source. The as-prepared CNTs/TiO2 samples are carefully characterized, analyzed and discussed. In contrast to previous reports with high CNT loading, our results indicate that a low CNT loading slightly influences the textural properties (including crystallite size, degree of crystallinity, specific surface areas, and pore volume etc.) and UV-light absorption of the mesoporous TiO2 aggregates. The SEM and TEM results demonstrate that the CNTs are mostly embedded in the mesoporous TiO2 aggregates. Moreover, chemical bonds are formed at the interface between CNTs and TiO2, which is confirmed by the Raman, IR and XPS analyses. Significantly, we point out that PL analysis in terms of intensity of PL signals seems to not be a reliable way to monitor the recombination rate in the CNTs/TiO2 composite, due to the quenching effect of CNTs. Instead, the analysis of transient photocurrent responses is introduced, which definitely reflects CNTs as fast electron transfer channels in chemically-bonded CNTs/TiO2 composites with low CNT loading. Notably, the positive synergy effects of CNTs and TiO2 depend on both the CNT loading amount and the state of interfacial contacts. In our study, only these chemically bonded CNTs/TiO2 nanocomposites with appropriate loading amounts ( 0.1 wt%) results in a decrease in photocatalytic activity; a simple mechanical mixing of CNTs and TiO2 without forming chemical bonds at the interface also results in inferior photocatalytic performance.
TL;DR: In this paper, the effect of different nanoparticles, their dispersion and the used modifiers, on polymer thermal stability was highlighted, highlighting the effect that hydrogen or covalent bonds can increase the adhesion of nanoparticles with the polymer matrix, resulting in higher dispersion degrees.
TL;DR: In this paper, an environmentally friendly and efficient route for the preparation of titanium oxide (TiO2) nanoparticles-reduced graphene oxide composite with a one-step hydrothermal method using glucose as the reducing agent was demonstrated.
Abstract: We demonstrated an environmentally friendly and efficient route for the preparation of titanium oxide (TiO2) nanoparticles-reduced graphene oxide composite with a one-step hydrothermal method using glucose as the reducing agent. The reducing process was accompanied by generation of TiO2 nanoparticles. The structure and composition of the nanocomposite has been characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction, thermal gravimetric analysis and atomic force microscopy. The TiO2-coated RGO nanocomposite was shown to improve the photocatalytic property of TiO2, which would be promising for practical applications in future nanotechnology.
TL;DR: The impact of CNT density on thermal conduction considering boundary resistances, increased defect concentrations, and the possibility of suppressed phonon modes in the CNTs is discussed.
Abstract: Nanostructured composites containing aligned carbon nanotubes (CNTs) are very promising as interface materials for electronic systems and thermoelectric power generators. We report the first data for the thermal conductivity of densified, aligned multiwall CNT nanocomposite films for a range of CNT volume fractions. A 1 vol % CNT composite more than doubles the thermal conductivity of the base polymer. Denser arrays (17 vol % CNTs) enhance the thermal conductivity by as much as a factor of 18 and there is a nonlinear trend with CNT volume fraction. This article discusses the impact of CNT density on thermal conduction considering boundary resistances, increased defect concentrations, and the possibility of suppressed phonon modes in the CNTs.
TL;DR: In this article, the authors summarize the development of polymer/graphite nanoplatelets (GNP) nanocomposites in recent years, including the fabrication of GNPs and its nan composites, processing issues, viscoelastic properties, mechanical properties, electrical and dielectric properties, thermal conductivity and thermal stability.
Abstract: Graphite nanoplatelets (GNPs) are a type of graphitic nanofillers composed of stacked 2D graphene sheets, having outstanding electrical, thermal, and mechanical properties. Furthermore, owing to the abundance of naturally existing graphite as the source material for GNPs, it is considered an ideal reinforcing component to modify the properties of polymers. The 2D confinement of GNPs to the polymer matrix and the high surface area make the GNP a distinctive nanofiller, showing superiorities in modification of most properties, compared with other carbon nanofillers. This review will summarize the development of polymer/GNP nanocomposites in recent years, including the fabrication of GNPs and its nanocomposites, processing issues, viscoelastic properties, mechanical properties, electrical and dielectric properties, thermal conductivity and thermal stability. The discussion of reinforcing effect will be based on dispersion, particle geometry, concentrations, as well as the 2D structures and exfoliation of GNPs. The synergy of GNPs with other types of carbon nanofillers used as hybrid reinforcing systems shows great potential and could significantly broaden the application of GNPs. The relevant research will also be included in this review.
TL;DR: The interaction between carbon nanotubes and polymers is critically reviewed in this article, where various techniques of interaction measurements, including experimental and modelling studies, are described, including wetting, spectroscopy and probe microscopy techniques are discussed in detail.
TL;DR: A methodology was developed to immobilize RGO-composites on river sand (RS) using chitosan as the binder and the as-supported composites are found to be efficient adsorbent candidates for field application.
TL;DR: In this paper, the liquid−solid phase change enthalpy, crystallization, and thermal conductivity of graphene/1-octadecanol (stearyl alcohol) composite, a nanostructured phase change material, was investigated as a function of graphene content.
Abstract: The liquid−solid phase change enthalpy, crystallization, and thermal conductivity of graphene/1-octadecanol (stearyl alcohol) composite, a nanostructured phase change material, was investigated as a function of graphene content. The thermal conductivity (κ) of the nanocomposite increased by nearly 2.5-fold (∼140% increase) upon ∼4% (by weight) graphene addition while the drop in the heat of fusion (i.e., storage capacity) was only ∼15.4%. The enhancement in thermal properties of 1-octadecanol obtained with the addition of graphene is markedly superior to the effect of other nanofillers such as silver nanowires and carbon nanotubes reported previously in the literature. Boosting the thermal conductivity of organic phase change materials without incurring a significant loss in the heat of fusion is one of the key issues in enabling their practical application as latent heat storage/release units for thermal management and thermal protection.
TL;DR: The graphene nanosheets in the composite materials could act not only as lithium storage active materials, but also as an electronically conductive matrix to improve the electrochemical performance of Fe(3)O(4).
Abstract: Fe3O4-graphene composites with three-dimensional laminated structures have been synthesised by a simple in situ hydrothermal method. From field-emission and transmission electron microscopy results, the Fe3O4 nanoparticles, around 3-15 nm in size, are highly encapsulated in a graphene nanosheet matrix. The reversible Li-cycling properties of Fe3O4-graphene have been evaluated by galvanostatic discharge-charge cycling, cyclic voltammetry and impedance spectroscopy. Results show that the Fe3O4-graphene nanocomposite with a graphene content of 38.0 wt% exhibits a stable capacity of about 650 mAh g(-1) with no noticeable fading for up to 100 cycles in the voltage range of 0.0-3.0 V. The superior performance of Fe3O4-graphene is clearly established by comparison of the results with those from bare Fe3O4. The graphene nanosheets in the composite materials could act not only as lithium storage active materials, but also as an electronically conductive matrix to improve the electrochemical performance of Fe3O4.
TL;DR: Clay nanopaper extends the property range of cellulose nanopaper and is of interest in self-extinguishing composites and in oxygen barrier layers and in fire retardance and oxygen permeability characteristics were measured.
TL;DR: In this paper, the tensile strength and storage modulus of polyurethane (PU) composites reinforced with graphene nanosheets (GNSs) were prepared by in situpolymerization.
Abstract: Polyurethane (PU) composites reinforced with graphene nanosheets (GNSs) were prepared by in situpolymerization. Graphene nanosheets, which were derived from chemically reduced graphite oxide (GO) nanosheets, were characterized by solid-state 13C MAS NMR, XRD and FTIR. A morphological study showed that, due to the formation of chemical bonds, the GNS was dispersed well in the PU matrix. With the incorporation of 2.0 wt% of GNSs, the tensile strength and storage modulus of the PU increased by 239% and 202%, respectively. The nanocomposites displayed high electrical conductivity, and good thermal stability of PU was also achieved. The facile and rapid technique presented here will provide an effective and promising method of preparing graphene-based polymer composites.
TL;DR: It is suggested that the strong interaction between h-BT fillers and PVDF matrix is the main reason for the improved dielectric properties of the h- BT/PVDF composites.
Abstract: Dielectric properties of poly(vinylidene fluoride) (PVDF) based nanocomposites filled with surface hydroxylated BaTiO(3) (h-BT) nanoparticles were reported. The h-BT fillers were prepared from crude BaTiO(3) (c-BT) in aqueous solution of H(2)O(2). Results showed that the dielectric properties of the h-BT/PVDF nanocomposites had weaker temperature and frequency dependences than that of c-BT/PVDF nanocomposites. Meanwhile, the h-BT/PVDF composites showed lower loss tangent and higher dielectric strength. It is suggested that the strong interaction between h-BT fillers and PVDF matrix is the main reason for the improved dielectric properties.
TL;DR: A gas-liquid interfacial synthesis approach has been developed to prepare SnO2/graphene nanocomposite as discussed by the authors, which is a promising anode material for lithium-ion batteries.
TL;DR: In this article, a cost-effective approach to construct a flexible interphase structure, strong interfacial interaction and good dispersion of functionalized graphene in epoxy nanocomposites through a local epoxy-rich environment around graphene oxide sheets, which reinforces the polymer properties and indicates further application in research and industrial areas.
Abstract: In order to obtain homogeneous dispersion and strong filler-matrix interface in epoxy resin, graphene oxide was functionalized via surface modification by hexachlorocyclotriphosphazene and glycidol and then incorporated into epoxy resin to obtain nanocomposites via in situ thermal polymerization. The morphology of nanocomposites was characterized by scanning electron microscopy and transmission electron microscopy, implying good dispersion of graphene nano-sheets. The incorporation of functionalized graphene oxide effectively enhanced various property performances of epoxy nanocomposites. The storage modulus of the epoxy nanocomposites was significantly increased by 113% (2% addition) and the hardness was improved by 38% (4% addition). Electrical conductivity was improved by 6.5 orders of magnitude. Enhanced thermal stability was also achieved. This work demonstrates a cost-effective approach to construct a flexible interphase structure, strong interfacial interaction and good dispersion of functionalized graphene in epoxy nanocomposites through a local epoxy-rich environment around graphene oxide sheets, which reinforces the polymer properties and indicates further application in research and industrial areas.
TL;DR: Polyurethane/cellulose nanocrystal nanocomposites with ultra-high tensile strength and stain-to-failure with strongly improved modulus were prepared by adding cellulose Nanocrystals (CNCs) during th...
Abstract: Polyurethane/cellulose nanocrystal nanocomposites with ultrahigh tensile strength and stain-to-failure with strongly improved modulus were prepared by adding cellulose nanocrystals (CNCs) during th ...
TL;DR: In this article, a thermally reduced graphene oxide (TRG) was blended via melt and solvent blending with linear low density polyethylene (LLDPE) and its functionalized analogs (amine, nitrile and isocyanate) produced using a ring-opening metathesis polymerization (ROMP) strategy.
TL;DR: Homogeneous nanocomposites with high rate capability and reversible lithium storage capacity and good rate performance are ideal candidates for electric vehicle applications where high power and energy density are primary requirements.
Abstract: Mesoporous carbon with homogeneously dispersed multi-walled carbon nanotubes (MWNTs) are synthesized via a one-step brick and mortar soft-templating approach. Nanocomposites exhibit high rate capability and reversible lithium storage capacity of 900 mA h g-1 and good rate performance. Such homogeneous nanocomposites are ideal candidates for electric vehicle applications where high power and energy density are primary requirements.