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Carbon nanofillers in general and graphene in particular are considered as promising potential candidates in catalysis due to their two‐dimensional (2D) nature, zero bandwidth, single atom thickness with a promising high surface area: volume ratio. Additionally, graphene oxide via result of tunable electrical properties has also been developed as a catalytic support for metal and metal oxide nanofillers. Moreover, the possession of higher chemical stability followed by ultrahigh thermal conductivity plays a prominent role in promoting higher reinforcement of catalytically active sites. In this review we have started with an overview of carbon nanofillers as catalyst support, their main characteristics and applications for their use in heterogeneous catalysis. The review article also critically focusses on the catalytic properties originating from both functional groups as well as doping. An in‐depth literature on the various reaction catalysed by metal oxide based nanoparticles supported on GO/rGO has also been incorporated with a special focus on the overall catalytic efficiency with respect to graphene contribution. The future research prospective in the aforementioned field has also been discussed. [ABSTRACT FROM AUTHOR]

With the constant increase of electronic waste globally, society is demanding and governments are boosting the development of electronics with less pollutant materials and reduced environmental impact. One way to achieve this is to implement materials that are functional and structural at the same time, reducing material use and assembling parts. Further, printing techniques, such as screen printing, reduce considerably costs and time compared with conventional electronics; combined with methods to conform printed electronics to a 3D shape, such as thermoforming, allow to obtain nonplanar surface electronics simply and efficiently. Herein, screen‐printable inks made of styrene–ethylene/butylene–styrene and different aspect‐ratio carbon‐based materials for conformable electronics are reported. The inks are prepared with carbon black, carbon nanotubes, and reduced graphene oxide as conductive fillers, printed on a flexible substrate and thermoformed. Carbon black and carbon nanotube samples are functional after the process, with conductivities of 96 and 141 S m−1 for the best performing sample of each filler, respectively. Rheological, morphological, thermal, and electrical properties of the materials are also characterized. This study shows the influence of the filler's type and aspect ratio on the morphology and electrical conductivity of the printed materials before and after thermoforming. [ABSTRACT FROM AUTHOR]

The development of multifunctional and high-performance fibers has received much attention owing to a broad application prospect. In this work, the synergistic effect of ionic liquid modification on dispersion of graphene and carbon nanotubes in polyamide 6(PA6) was studied, and the composite fiber was prepared using melt spinning after a simple pre-solution blending. Imidazole chloride ionic liquid is adsorbed on the surface of the two carbon nanofillers through non-covalent bond, which gives a good dispersion and interface bonding in PA6 matrix. When the mass ratio of functionalized carbon nanofillers is 1:2, the mechanical properties and thermal stability of PA6 composite fiber are significantly improved compared with the pure PA6 fiber. Moreover, the PA6 composite fiber has a UV protection factor (UPF) of 158.2 and good antistatic performance with a surface resistivity of 2.60 × 107 Ω · cm. In addition, there is an excellent photothermal conversion performance from the results of 200 W infrared light irradiation test and outdoor photothermal experiments. This work provides a new idea to prepare multifunctional and high-performance composite fibers. [ABSTRACT FROM AUTHOR]

In this work, polymer blend nanocomposites based on carbon fillers were produced via melt‐compounding in a twin‐screw extruder. A combination of several matrices (LLDPE, EMA, and LLDPE/EMA) and fillers (FLG, FWCNT, and FLG/FWCNT) was used. Thermal enhancement as the consequence of few‐walled carbon nanotube addition, led to significant improvements in the initial degradation temperatures of LLDPE (383.2 > 441.2°C), EMA (371.2 > 417.3°C), and LLDPE/EMA (390.55 > 430.62°C) matrixes, respectively. The evaluation of the dynamic‐mechanical behavior of the compositions showed an increase of 80% in the storage module for LLDPE‐based nanocomposites, a reduction of 30% for blend‐based nanocomposites, and a non‐change for EMA nanocomposites. Tenacity property was considerably improved, achieving a value 78% higher to the LLDPE/EMA blend, mainly due to the possible migration of the nanoparticles from EMA phase to the LLDPE phase, creating a more efficient physical network with well‐developed percolating structure, which facilitates the dissipation of energy during mechanical loading. In summary, it can be observed that the morphology control as well as the nanofillers location, proved to be extremely relevant factors to produce a polymer film with enormous gains in the thermal and mechanical properties. [ABSTRACT FROM AUTHOR]

Poly(ethylene 2,5-furandicarboxylate) (PEF) nanocomposites reinforced with Graphene nanoplatelets (GNPs) and Carbon nanotubes (CNTs) were in situ synthesized in this work. PEF is a biobased polyester with physical properties and is the sustainable counterpart of Polyethylene Terephthalate (PET). Its low crystallizability affects the processing of the material, limiting its use to packaging, films, and textile applications. The crystallization promotion and the reinforcement of PEF can lead to broadening its potential applications. Therefore, PEF nanocomposites reinforced with various loadings of GNPs, CNTs, and hybrids containing both fillers were prepared, and the effect of each filler on their structural characteristics was investigated by X-ray Diffraction (XRD), Fourier transform infrared spectroscopy—attenuated total reflectance (FTIR–ATR), and X-Ray Photoelectron Spectroscopy (XPS). The morphology and structural properties of a hybrid PEF nanocomposite were evaluated by Transmission Electron Microscopy (TEM). The thermo-oxidative degradation, as well as lifetime predictions of PEF nanocomposites, in an ambient atmosphere, were studied using Thermogravimetric Analysis (TGA). Results showed that the fillers' incorporation in the PEF matrix induced changes in the lamellar thickness and increased crystallinity up to 27%. TEM analysis indicated the formation of large CNTs aggregates in the case of the hybrid PEF nanocomposite as a result of the ultrasonication process. Finally, the presence of CNTs caused the retardation of PEF's carbonization process. This led to a slightly longer lifetime under isothermal conditions at higher temperatures, while at ambient temperature the PEF nanocomposites' lifetime is shorter, compared to neat PEF. [ABSTRACT FROM AUTHOR]

We report measurements of linear and nonlinear elastic properties of polystyrene-based nanocomposites with six types of nanofillers, including single and binary mixtures of allotropic carbon nanoparticles. Composite samples were fabricated by the same technology and contained the same filler concentration (5% wt.), which allowed for a direct comparison of their properties. It was shown that the most significant variations of linear and nonlinear elastic properties occur in different nanocomposites. In particular, the most pronounced enhancements of linear elastic moduli (in about 50%) obtained in tensile and flexural tests and in dynamic mechanical analysis were recorded in the sample filled with spherical fullerene nanoparticles. While the most profound rise of absolute values of nonlinear elastic moduli (tens of times) was obtained in the sample filled with the mixture of carbon nanotubes and graphene. The observed tendencies demonstrated the synergistic effect of fillers of different dimensionality on the elastic properties of nanocomposites. [ABSTRACT FROM AUTHOR]

The commercial viability of fuel cells for vehicle application has been examined in the context of lightweight material options, as well as in combination with improvements in fuel cell powertrain. Investigation into ultra-lightweight bipolar plates (BPs), the main component in terms of the weight effect, is of great importance to enhance energy efficiency. This research aims to fabricate a layered carbon fiber/epoxy composite structure for BPs. Two types of carbon fillers (COOH-MWCNT and COOH-GNP) reinforced with woven carbon fiber sheets (WCFS) have been utilized. The conceptual idea is to reduce molding cycle time by improving the structural, electrical, and mechanical properties of BPs. Reducing the reactive molding cycle time is required for commercial production possibility. The desired crosslink density of 97%, observed at reactive molding time, was reduced by 83% at 140 °C processing temperature. The as-fabricated BPs demonstrate excellent electrical conductivity and mechanical strength that achieved the DOE standard. Under actual fuel cell operation, the as-fabricated BPs show superior performance to commercial furan-based composite BPs in terms of the cell potential and maximum power. This research demonstrates the practical and straightforward way to produce high-performance and reliable BPs with a rapid production rate for actual PEMFC utilization. [ABSTRACT FROM AUTHOR]

Carbonaceous nanofillers, namely carbon nanotubes (CNT) and graphene‐based nanoparticles (GNP), have truly attractive physical and mechanical properties such as high elastic modulus, as well as noteworthy thermal and electrical conductivities. This has inevitably stimulated a growing interest toward the development of CNT and GNP‐based composites with improved mechanical and electrical properties for application in aeronautics, aerospace, automotive, nautical, and in general, infrastructural field. In this context, understanding the rheological behavior of nanocomposites loaded with one‐dimensional (1D) and bi‐dimensional (2D) carbon fillers is crucial for optimizing the manufacturing process of carbon fiber reinforced panels (CFRPs) and for obtaining information on whether the structure is percolated. This study demonstrates the special ability of the analyzed systems to guarantee good rheological properties, thus confirming their applicability as structural materials in a wide temperature range. [ABSTRACT FROM AUTHOR]

Due to extensive concerns of tremendous environment pollutions, particularly microplastic as an emerging pollutant, the development and investigate on biodegradable polymer foams raised growing interest and revealed promising application prospects. In this work, carbon nanotubes (CNTs) and graphene nanosheets (GNPs) were introduced into poly (butylene adipate-co-terephthalate) (PBAT) foams to develop micro-nano bimodal cellular structure (BCS) using a supercritical CO2 foaming approach. CNTs and GNPs (CG) network structures were formed in PBAT/CNTs/GNPs nanocomposites by the gradual addition of CG, which made a significant enhancement on their melt viscoelasticity. Systematically, the effect of CG content and foaming temperature on the PBAT cellular structure were investigated. As the CG content increased, BCS was steadily formed in the PBAT/CG foams, meanwhile, their cell size decreased. At last, the generation mechanism of BCS in different PBAT/CG foams was explored. [ABSTRACT FROM AUTHOR]

Nanomechanical definition of the properties of composite specimens based on polylactic acid (PLA) was made in the present study. Research activities with accent on biodegradable polymer nanocomposites have fundamental significance originated from the worldwide plastic waste pollution. To receive hybrid nanocomposites with high level of homogeneity, the low cost and environmentally friendly melt extrusion method has been applied. The role of graphene nanoplatelets (GNPs) and multiwall carbon nanotubes (MWCNTs) as reinforcing nanoparticles dispersed in the polymer matrix was thoroughly investigated. Quasi-static nanoindentation analysis was enriched by performance of accelerated property mapping and nanodynamic mechanical testing in order to fully describe the nanoscale surface homogeneity and stress relaxation behavior of the nanocomposite specimens. That novelty of the research approach had a well-marked contribution over the detection of the new samples' nanomechanical features as a function of the type of carbon nanofiller. Refined nanoscratch experiments uncovered the resistance of the materials against notches by means of measurement of the coefficient of friction and accurate estimation of the residual penetration depth. [ABSTRACT FROM AUTHOR]

In the present work, Pebax-1657, a commercial multiblock copolymer (poly(ether-block-amide)), consisting of 40% rigid amide (PA6) groups and 60% flexible ether (PEO) linkages, was selected as the base polymer for preparing dense flat sheet mixed matrix membranes (MMMs) using the solution casting method. Carbon nanofillers, specifically, raw and treated (plasma and oxidized) multi-walled carbon nanotubes (MWCNTs) and graphene nanoplatelets (GNPs) were incorporated into the polymeric matrix in order to improve the gas-separation performance and polymer’s structural properties. The developed membranes were characterized by means of SEM and FTIR, and their mechanical properties were also evaluated. Well-established models were employed in order to compare the experimental data with theoretical calculations concerning the tensile properties of MMMs. Most remarkably, the tensile strength of the mixed matrix membrane with oxidized GNPs was enhanced by 55.3% compared to the pure polymeric membrane, and its tensile modulus increased 3.2 times compared to the neat one. In addition, the effect of nanofiller type, structure and amount to real binary CO2/CH4 (10/90 vol.%) mixture separation performance was evaluated under elevated pressure conditions. A maximum CO2/CH4 separation factor of 21.9 was reached with CO2 permeability of 384 Barrer. Overall, MMMs exhibited enhanced gas permeabilities (up to fivefold values) without sacrificing gas selectivity compared to the corresponding pure polymeric membrane.

Nanocarbon materials are critical ingredients with unique properties in emerging materials. In this study, various carbon nanofillers, such as carbon nanotube (CNT), graphene oxide (GO), reduced GO wrapped by poly(styrene sulfonate) (PSS-RGO), and graphite nanoplatelet (GNP), were utilized to examine the effects of nanofiller types and surface treatments on the electrical and rheological properties of polystyrene (PS) nanocomposites prepared by latex-based process. The PS/CNT nanocomposites exhibited the most enhanced electrical and rheological properties among the composites evaluated. The PS/GO nanocomposites showed improved rheological properties and significantly increased electrical conductivity, despite the decrease in the intrinsic properties of graphene due to the change in hybridization from sp2 to sp3 by strong acid treatment. Interestingly, they exhibited higher conductivity than PS/PSS-RGO due to the higher graphene moiety and the thermal reduction of GOs during compression molding. The PS/GNP nanocomposites showed marginal enhancement because GNP is a larger aggregate of graphene layers bonded by van der Waals force. The results of this study on the electrical and rheological properties, surface modification, and size and dispersion of conductive nanofillers in an insulating polymer matrix are beneficial for the development and application of electrically conductive nanocomposites. [ABSTRACT FROM AUTHOR]

The development of information transmission technology towards high-frequency microwaves and highly integrated and multi-functional electronic devices has been the mainstream direction of the current communication technology. During signal transmission, resistance-capacitance time delay, crosstalk, energy consumption increase and impedance mismatch restrict the high density and miniaturization of Printed circuit board (PCB). In order to achieve high fidelity and low delay characteristics of high-frequency signal transmission, the development of interlayer dielectric materials with low dielectric constant (Dk) and low dielectric loss factor (Df) has become the focus of researchers. This review introduces the dielectric loss mechanism of polymer composites and the resin matrix commonly used in several high-frequency copper-clad laminates, and mainly describes how to reduce the dielectric constant and dielectric loss of materials from the level of molecular structure design, as well as the effect of fillers on the dielectric properties of polymer substrates. As a kind of potential functional fillers for dielectric polymeric composites, the carbon nanofillers are used to tailor the dielectric properties of their composites via different dimensions and loadings, as well as their proper preparation methods. This review finally summarizes the interface bonding failure mechanism and a feasible idea to optimize the dielectric properties of polymer matrix composites is also proposed.

Polylactic acid (PLA) is the most wide-scale investigated biodegradable and renewable under specific processing conditions thermoplastic polyester. As bioplastic material, it has the potential to be used as a substituent of conventional polymers derived from fossil fuel resources. The drawbacks possessed by PLA as poor thermal and electrical properties, mechanical brittleness, and ability to undergo polymer chain degradation in ambient medium could be overcome by incorporation of carbon nanofillers in the PLA matrix. Raman spectroscopy was used to study the effect of graphene nanoplatelets (GNPs) and multiwall carbon nanotubes (MWCNTs) on the nanocomposite molecular morphology and structure. The carbon nanofillers impact on the crystallinity of the melt blended hybrid material and the changes in the composite architecture were defined by applying of physical methods as X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Thermo-gravimetric analysis (TGA) was implemented to outline the thermal properties of the nanocomposites. An excellent homogeneity and firmly expressed crystalline structure of the produced composite materials were disclosed. Tensile testing showed that coupling GNPs and MWCNTs has higher positive effect on ultimate tensile strength of the nanocomposites and lower influence on Young's modulus of elasticity. [ABSTRACT FROM AUTHOR]

The synergistic effect of two carbon nanofillers on the mechanical properties of PLA-based nanocomposites was investigated in the present work. Polylactic acid is relatively brittle semi-crystalline polymer which was selected for composite matrix because of its biodegradable properties. It was reinforced with graphene nanoplatelets and multiwall carbon nanotubes by means of melt mixing preparation method. Nanohardness and Young's modulus of smooth nanocomposite samples received by 3D printing were defined by nanoindentation experiments using Berkovich-type pyramidal nanoindenter. It was found that the compounds, incorporated with both graphene and carbon nanotubes in the polymer structure, exhibit better mechanical performance compared to the nanocomposites loaded with a single carbon nanofiller. Different techniques of sample preparation were applied in order to see the influence of preliminary processing on the nanomechanical properties of composite specimens. X-ray diffraction and Raman spectroscopy were used to study the structural features of the pristine carbon nanomaterials. [ABSTRACT FROM AUTHOR]

The effect of synergistic reinforcement of two types of carbon nanofillers, carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs), on the corrosion behavior of plasma‐sprayed alumina (Al2O3) nanocomposite coating in 3.5 wt% NaCl solution is studied. Incorporation of 1 wt% CNT and 0.5 wt% GNP into the Al2O3 matrix reduces the corrosion current density of the matrix from 2.78 to 0.21 μA cm−2, which drastically leads to a 13 times reduction in the corrosion rate of the Al2O3 matrix as compared with pure Al2O3 coating. The plausible reasons to this improvement are characterized by the filling of gaps, crevices, and microholes in the Al2O3 matrix by CNTs and GNPs and hydrophobic nature as well as chemical inertness of these reinforcements to the aggressive environment. Further, the corrosion products are analyzed by X‐ray diffraction and Raman spectroscopy for a much deeper insight into the mechanism of corrosion protection by these carbonaceous reinforcements. For the first time, the effect of CNT and GNP reinforcement on the corrosion behavior of plasma‐sprayed coatings is investigated. [ABSTRACT FROM AUTHOR]

Nanomaterials have already been explored their potential for interlaminar toughening and crack-monitoring capabilities within the field of composite materials. However, efficient enhancement of interlaminar fracture toughness remains an unresolved challenge. Herein, a novel integrated filler spray and nanosecond pulsed electric field (nsPEF)-assisted curing technique is proposed for the fabrication of high-performance composite material system for the first time. The spraying technique proves to be an effective approach for depositing fillers, including carbon nanotubes (CNTs), graphene nanoplatelets (GNPs), and carbon nanofibers (CNFs), onto carbon fiber prepreg. Meanwhile, the nsPEF-assisted technique is utilized to enhance the wettability of resin to fiber, thus reducing void defects. The efficacy of this integrated technique is evidenced by the particularly low content of fillers (0.047 wt%). The experimental results show a substantial reduction of porosity in the composite by 49.36% (from 1.56% to 0.79%). Meanwhile, the mode I initiation and steady-state toughness of samples with CNTs and GNPs are remarkably improved by up to 47% and 82%, respectively, compared to the baseline. This represents the most significant improvement reported to date for non-functionalized CNTs and GNPs at such low concentrations. Moreover, the relative electrical resistance variation (Δ R / R 0 %) of CNT/GNP sensors used for in-situ damage sensing increased by ∼ 14%. This work pioneers the investigation of the synergistic effects of two promising techniques for preparing composite materials, offering advantages in terms of simplicity, multifunctionality, and the potential for industrial scalability. • A novel integrated nanofiller spray and nanosecond pulsed electric field (nsPEF)-assisted technique is proposed. • Enhanced wettability of resin to fiber and reduced porosity by 49.36% from 1.56% to 0.79%. • Improved mode I initiation and steady-state interlaminar fracture toughness by 47% and 82%, respectively. • Improved Δ R / R 0 % by 14% with CNT/GNP sensors for in-situ damage sensing. [ABSTRACT FROM AUTHOR]

Poly(lactic acid)/graphene and poly(lactic acid)/carbon nanotube nanocomposites were prepared by an easy and low-cost method of melt blending of preliminary grinded poly(lactic acid) (PLA) with nanosized carbon fillers used as powder. Morphological, structural and mechanical properties were investigated to reveal the influence of carbon nanofiller on the PLA–based composite. The dependence of tensile strength on nanocomposite loading was defined by a series of experiments over extruded filaments using a universal mechanical testing instrument. The applying the XRD technique disclosed that compounds crystallinity significantly changed upon addition of multi walled carbon nanotubes. We demonstrated that Raman spectroscopy can be used as a quick and unambiguous method to determine the homogeneity of the nanocomposites in terms of carbon filler dispersion in a polymer matrix. [ABSTRACT FROM AUTHOR]

In this study, thermally reduced graphene oxide (TRG)-containing polyurethane nanocomposites were obtained by the extrusion method. The content of TRG incorporated into polyurethane elastomer systems equaled 0.5, 1.0, 2.0 and 3.0 wt%. The morphology, static and dynamic mechanical properties, and thermal stability of the modified materials were investigated. The application of TRG resulted in a visible increase in material stiffness as confirmed by the measurements of complex compression modulus (E′) and glass transition temperature (Tg). The Tg increased with increasing content of nanofiller in the thermoplastic system. The addition of thermally reduced graphene oxide had a slight effect on thermal stability of the obtained materials. The incorporation of 0.5, 1.0, 2.0 and 3.0 wt% of TRG into a system resulted in increased char residues compared to unmodified PU elastomer. Also, this study demonstrated that after exceeding a specific amount of TRG, the physicomechanical properties of modified materials start to deteriorate.

Despite the indispensable contribution of crystallization to the final properties of poly(lactic acid) (PLA), the combined effect of steady shear and nanofiller(s) remains mostly unsettled. This work employed a combination of steady shear and oscillatory rheological measurements to study shear induced nano-structural breakdown and subsequent nanoparticle orientation and overall structural recovery in PLA nanocomposites containing functionalized, single and hybrid carbon nanofillers (fCNTs & fGnPs) with different dimensionalities. Similar rheological measurements were used to study the effect of the flow induced nanoparticle orientation on nonisothermal as well as isothermal crystallization of PLA under both applied pre-shear and quiescent conditions. It was found that addition of the carbon nanofillers into PLA had a significant intensifying effect on the flow induced contribution to the acceleration of the crystallization kinetics, particularly after a pre-shear. These findings could be explained in the light of the simultaneous increase in nucleation density and amplification of flow induced molecular orientation driven by the carbon nanofillers. In the case of the nanocomposites containing hybrids of the nanofillers showed greater enhancing effect on crystallization of PLA compared to mixture law predictions. This was attributed to the favorable effect of 2D fGnPs on the dispersion of 1D fCNTs which could, in turn, lead to the availability of a larger surface area of nanofillers and therefore stronger nanoparticle induced molecular orientation. Finally, the effect of increasing pre-shear rate on the flow sensitivity parameter defined as k ss /k q was found to be synergistic for all nanocomposite samples. [ABSTRACT FROM AUTHOR]

A new approach employing carbon nanostructure (CNS) buckypapers (BP) was used to prepare glass fiber/epoxy composite materials with enhanced resistance to delamination along with damage monitoring capability. The CNS-BP was subjected to plasma treatment to improve its wettability by epoxy and to promote stronger interfacial bonding. An increase up to 20% in interlaminar fracture toughness in mode I and mode II was observed in composite laminates incorporating CNS BP. Morphological analysis of the fracture surfaces indicated that failure in the conductive CNS layer provided a more effective energy dissipation mechanism, resulting in interlaminar fracture toughness increase. Moreover, fracture of the conductive CNS layer enabled damage monitoring of the composite by electrical resistance measurements upon delamination. The proposed approach provides multifunctional ply interphases, allowing to couple damage monitoring with interlaminar reinforcement of composite laminates. [ABSTRACT FROM AUTHOR]

The influence of superfine carbon additives and their pretreatment by ultrasonication on the properties of elastomer compositions has been investigated. Superfine carbon additives come in two different types: fullerene-containing additives and ultra fine carbon additives (a complex mixture of nanofibers and nanotubes, graphite and amorphous carbon particles). Mooney viscosity, parameters of relaxation and vulcanization kinetics of rubber mixtures, tensile strength, elongation at break and resistance to thermal aging, abrasion resistance and compression of filled rubbers based on butadiene-acrylonitrile were carried out. Except for the identified characteristics, crosslink parameters by the method of equilibrium swelling were determined. It was found that the introduction of the ultrasonically pretreated, superfine carbon additives to elastomeric compositions based on butadiene-acrylonitrile rubber led to rubber with improved thermo-oxidative and wear resistance in comparison to rubbers containing untreated additives. [ABSTRACT FROM AUTHOR]

In this study, we present carbon nanoparticle incorporated high-performance aromatic thermosetting copolyester (ATSP) nanocomposite foams. The ATSP nanocomposite foams were fabricated through a facile solid-state mixing method wherein carboxylic acid and acetoxy-functional group oligomers were initially combined with chemically pristine carbon nanofillers separately, while in powder form. The mixtures were then subjected to a thermal condensation polymerization reaction in which the constituent oligomers formed the ester backbone of the ATSP matrix and advanced the molecular weight while acetic acid was emitted as the by-product, and generated a porous nanocomposite morphology. As compared to a neat ATSP foam, the nanocomposite foams exhibited a reduced coefficient of thermal expansion by 25% to 75 × 10 −6 °C −1 . Thermal stability temperature at 5% mass loss was increased by 30 °C exceeding 500 °C. Compressive mechanical strength was enhanced two-fold, reaching 16 MPa along with a nearly doubled fracture strain, which ultimately yielded improved material toughness. [ABSTRACT FROM AUTHOR]

The effect of carbon nanotubes, graphene-like platelets, and another carbonaceous fillers of natural origin on the electrical conductivity of polymeric materials was studied. With the aim of keeping the filler content and the material cost as low as possible, the effect of laser surface treatments on the conductivity of polymer composites with filler load below the percolation threshold was also investigated. These treatments allowed processing in situ conductive tracks on the surface of insulating polymer-based materials. The importance of the kinds of fillers and matrices, and of the laser process parameters was studied. Carbon nanotubes were also used to obtain piezoresistive composites. The electrical response of these materials to a mechanical load was investigated in view of their exploitation for the production of pressure sensors and switches based on the piezoresistive effect. It was found that the piezoresistive behavior of composites with very low filler concentration can be improved with proper laser treatments.

Poly(lactic acid)/graphene and poly(lactic acid)/carbon nanotube nanocomposites were prepared by an easy and low-cost method of melt blending of preliminary grinded poly(lactic acid) (PLA) with nanosized carbon fillers used as powder. Morphological, structural and mechanical properties were investigated to reveal the influence of carbon nanofiller on the PLA⁻based composite. The dependence of tensile strength on nanocomposite loading was defined by a series of experiments over extruded filaments using a universal mechanical testing instrument. The applying the XRD technique disclosed that compounds crystallinity significantly changed upon addition of multi walled carbon nanotubes. We demonstrated that Raman spectroscopy can be used as a quick and unambiguous method to determine the homogeneity of the nanocomposites in terms of carbon filler dispersion in a polymer matrix.

In this paper, the electrical and thermal conductivity and morphological behavior of low density polyethylene (LDPE)/multi-walled carbon nanotubes (MWCNTs) + graphene nanoplatelets (GNPs) hybrid nanocomposites (HNCs) have been studied. The distribution of MWCNTs and the hybrid of MWCNTs/GNPs within the polymer matrix has been investigated with scanning electron microscopy (SEM). The results showed that the thermal and electrical conductivity of the LDPE-based nanocomposites increased along with the increasing content of carbon nanofillers. However, one could observe greater improvement in the thermal and electrical conductivity when only MWCNTs have been incorporated. Moreover, the improvement in tensile properties and thermal stability has been observed when carbon nanofillers have been mixed with LDPE. At the same time, the increasing content of MWCNTs and MWCNTs/GNPs caused an increase in the melt viscosity with only little effect on phase transition temperatures.

Two ethylene/1-butene thermoplastic elastomer copolymers were melt mixed with either multiwalled carbon nanotubes ( CNTs) or thermally reduced graphite oxide ( TrGO) resulting in piezoresistive composite materials. The effect of the polymer matrix, carbon nanostructure and filler concentration on the electrical behavior of the sensors was analyzed. The percolation process confirmed the relevance of these parameters as different thresholds were found depending on both the matrix and the filler. For instance, composites based on TrGO presented higher percolation thresholds than those based on CNTs. Regarding the strain sensor behavior of the electrically conductive composites, by using a matrix with a low amount of 1-butene comonomer, higher resistance sensitivities were observed compared with the other matrix. Noteworthy, composites based on TrGO filler presented strain sensitivities one order of magnitude higher than composites based on CNT filler. These results are explained by the excluded volume theory for percolated systems. Based on these findings, polyethylene piezoresistive sensors can be designed by a proper selection of polymer matrix, filler concentration and carbon nanoparticles. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The addition of carbon nanofillers to phase change materials (PCMs) has received much attentions recently. The shape effects of carbon nanofillers on the thermal properties of paraffin were investigated in this work. Four types of nanocomposite PCMs were prepared by mixing paraffin with multi-wall carbon nanotubes (MWCNTs), graphitized MWCNTs, nanographene with different layer numbers (GNP-B, GNP-C). It shows that phase change enthalpy of nanocomposite PCM decreases gradually with the increasing of the loading of carbon nanofillers. Due to the nucleating action of carbon nanofillers, the supercooling degree of nanocomposite PCM slightly decreases. The microstructure of the nanofillers plays an important role in enhancing the thermal conductivity of paraffin. It is the flaky structure of GNP shows a more significant effect on enhancing the thermal conductivity of paraffin than the tubular structure of CNTs, which is confirmed by comparing the melting/freezing time of PCM. In the four kinds of carbon nanofillers, GNP-C shows the greatest thermal conductivity enhancement up to 52.4 % at the loading of 3 mass%. [ABSTRACT FROM AUTHOR]

Polyurethane thermoplastic elastomer (TPU) nanocomposites were prepared by the incorporation of 1 wt% of high-structured carbon black (HSCB), carbon nanofibers (CNF), nanosilica (NS) and nanoclays (NC), following a proper high-shear blending procedure. The TPU nanofilled mechanical properties and morphology was assessed. The nanofillers interact mainly with the TPU hard segments (HS) domains, determining their glass transition temperature, and increasing their melting temperature and enthalpy. A significant improvement upon the modulus, sustained stress levels and deformation capabilities is evidenced. The relationships between the morphology and the nanofilled TPU properties are established, evidencing the role of HS domains on the mechanical response, regardless the nanofiller type. [ABSTRACT FROM AUTHOR]

Polyamide 6 (PA6) matrix composites were prepared by incorporating multiwalled carbon nanotubes (MWCNTs) or by co-incorporating MWCNTs and carbon black (CB) of different contents. The thermal, mechanical and tribological properties of the composites were investigated using thermogravimetric analysis, nano-indentation, ball-on-disc micro-tribological test and micro-scratch test. It was found that a proper carbon filler content in the composites promoted the thermal stability of the composites, but an excessive loading of carbon fillers degraded the thermal stability of the composites. Although the hardness of the composites decreased with increased carbon filler content, the composites filled with mixed MWCNTs and CB had a higher load bearing capacity than the ones without CB. The tribological results indicated that the increased carbon filler content apparently lowered the friction coefficient of the composites due to the lubricating effect of the carbon fillers. It was also observed that the friction coefficients of the PA6-MWCNT-CB composites were consistently higher than those of the PA6-MWCNT composites due to the lower wear resistance of the PA6-MWCNT-CB composites. The scratch resistance of the composites decreased with increased carbon filler content due to the reduced cohesive strength of the composites. [ABSTRACT FROM AUTHOR]

Epoxy nanocomposites with commercial carbon nanotubes (CNT) or graphene (GN) have been prepared using phosphonium ionic liquid [trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl) phosphinate, IL-f]. IL-f served simultaneously as nanofiller dispersing medium and epoxy resin catalytic curing agent. An influence of IL-f/epoxy weight ratio (3, 6 and 9/100, phr), carbon nanofiller type and content on viscosity of epoxy compositions during storage at ambient temperature was evaluated. Curing process was controlled for neat and CNT or GN modified epoxy compositions (0.25- 1.0 wt% load) using differential scanning calorimetry and rheometry. Epoxy nanocomposites exhibited slightly increased glass transition temperature values (146 to 149°C) whereas tan δ and storage modulus decreased (0.30 to 0.27 and 2087 to 1070 MPa, respectively) as compared to reference material. Crosslink density regularly decreased for composites with increasing CNT content (11 094 to 7020 mol/m3). Electrical volume resistivity of the nanocomposites was improved in case of CNT to 4 ∙ 101 Ω ∙ m and GN to 2 ∙ 105 Ω ∙ m (nanofiller content 1 wt%). Flame retardancy was found for modified epoxy materials with as low GN and phosphorus content as 0.25 and 0.7 wt%, respectively (increase of limiting oxygen index to 26.5%). [ABSTRACT FROM AUTHOR]

Highlights: [•] Paraffin-based nanocomposite PCMs were prepared with various carbon nanofillers. [•] The decrease in energy storage capacity of GNP-based composite was moderate. [•] Phase change temperatures were slightly lowered in the presence of the nanofillers. [•] Greater enhancement was achieved with decreasing the size of wire-shaped fillers. [•] GNPs caused greatest thermal conductivity enhancement up to 164% at 5wt.%. [ABSTRACT FROM AUTHOR]

The key to the preparation of polymer nanocomposites with new or improved properties resides in the homogeneous dispersion of the filler and in the efficient load transfer between components through strong filler/polymer interfacial interactions. This paper reports on the preparation of a series of nanocomposites of graphene and a polyolefin using different experimental approaches, with the final goal of obtaining multifunctional materials. A high-density polyethylene (HDPE) is employed as the matrix, while unmodified and chemically modified graphene fillers are used. By selecting the correct combination as well as the adequate preparation process, the nanocomposites display optimized thermal and mechanical properties, while also conferring good gas barrier properties and significant levels of electrical conductivity. [ABSTRACT FROM AUTHOR]

• Superhydrophobic PVDF/fluorinated ethylene propylene/SiO 2 (PFS)-carbon nanotubes (CNTs) coating was fabricated. • Tackling effect of CNTs can prevent the adhesion of CaCO 3 on the surface of the superhydrophobic PFS-CNTs coating. • The air film can be maintained in the superhydrophobic PFS-CNTs coating surface for antiscaling. • The superhydrophobic PFS-CNTs coating exhibits an excellent antiscaling perfo- rmance. Superhydrophobic poly(vinylidene fluoride)/fluorinated ethylene propylene/SiO 2 (PFS) composite coatings incorporating various carbon nanofillers, such as carbon nanotubes (CNTs), carbon nanofibers (CNFs), graphene nanoplates (GnPs) and carbon black (CB) respectively, were successfully fabricated by spraying. The scale-inhibition properties of these coatings were tested in a CaCO 3 supersaturated solution, and the deposited CaCO 3 scale was characterized with SEM and XRD. The effects of carbon nanofillers on the surface roughness, surface energy, and scale inhibition behaviors of different coatings were studied. In contrast with GnPs, CNFs and CB, the CNTs were dispersed more uniformly in the PVDF matrix and formed a stronger bond with the polymer matrix. The addition of CNTs changed the morphology, increased the surface roughness, and further reduced the surface energy of the superhydrophobic PFS-CNTs composite coating owing to the tackling effect of CNTs. A stable air film was maintained on the surface of superhydrophobic PFS-CNTs composite coating, which was more favorable for superhydrophobic retention by wrapping air in the saturated CaCO 3 solution. The CaCO 3 scaling rate on the superhydrophobic PFS-CNTs composite coating was only 44 % of that on the hydrophobic PFS composite coating, which showing the highest antiscaling performance. [ABSTRACT FROM AUTHOR]

• Dispersion analysis of different carbon based nanofillers in water. • Morphology of carbon nanofillers determines dispersibility. • Detailed porosity analysis of nanocomposites. • Porosity influenced by surfactant and nanofillers. The dispersion behaviour of different carbon-based nanofillers in deionized (DI) water was investigated in the study at hand by using polycarboxylates as surfactants. Carbon nanotubes (CNTs), carbon black (CB) and expanded graphite (EG) were firstly characterized in respect of their morphology. Subsequently, they were dispersed in DI water using two polycarboxylate (PCE) comb-type copolymers which differed in length of their chemical backbones. Optical microscopy and light transmission analysis during centrifugation disclosed a clear difference in the dispersibility among the nanofillers under investigation. Small CB particles showed excellent dispersion in DI water even with no surfactant. CNT was dispersed significantly better than EG, whereby the PCE with the longer backbone yielded better filler dispersion in both cases. After incorporating the carbon nanofillers into a cementitious matrix, interestingly, the highest compressive and flexural strengths at an early age were measured for the CNT samples with worse filler dispersion. This effect is explained by the role of the PCE and the aspect ratio of the carbon nanofiller, both of which determine the microstructure in the hardened cement-based matrix collaboratively. [ABSTRACT FROM AUTHOR]

A hybrid polymeric system containing carbon nanofillers with different geometrical dimensions is proposed for strategic applications, particularly for electrical properties. Two different carbon nanofillers including functionalized multiwalled carbon nanotubes (fCNTs) and functionalized graphene nanoplatelets (fGnPs) were added to thermoplastic polyurethane (TPU) to prepare single and hybrid nanofiller filled TPU through solution mixing. Sufficient exfoliation of the fGNPs in the single nanocomposites was confirmed by X‐ray diffraction, while single filler and hybrid TPU nanocomposites containing fCNTs showed some re‐aggregation of these nanofillers. Linear rheology together with scanning electron microscopy revealed a proper exfoliation and dispersion degree for fGnPs and fCNTs, respectively. We have shown that simultaneous addition of fCNTs–fGnPs in the form of a hybrid system into the TPU made a large surface area available and strong interfacial interactions were formed between the hybrid network and the TPU matrix. This in turn led to electrical, thermal and mechanical properties, which were superior to those predicted by the mixture law. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48520. [ABSTRACT FROM AUTHOR]