Carbon Nanofillers Research Articles

Graphene-Based Catalysts: Emerging Applications and Potential Impact.

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.

Chemistry of Reduced Graphene Oxide: Implications for the Electrophysical Properties of Segregated Graphene-Polymer Composites.

Conductive polymer composites (CPCs) with nanocarbon fillers are at the high end of modern materials science, advancing current electronic applications. Herein, we establish the interplay between the chemistry and electrophysical properties of reduced graphene oxide (rGO), separately and as a filler for CPCs with the segregated structure conferred by the chemical composition of the initial graphene oxide (GO). A set of experimental methods, namely X-ray photoelectron spectroscopy (XPS), ultraviolet-visible spectroscopy, van der Paw and temperature-dependent sheet resistance measurements, along with dielectric spectroscopy, are employed to thoroughly examine the derived materials. The alterations in the composition of oxygen groups along with their beneficial effect on nitrogen doping upon GO reduction by hydrazine are tracked with the help of XPS. The slight defectiveness of the graphene network is found to boost the conductivity of the material due to facilitating the impact of the nitrogen lone-pair electrons in charge transport. In turn, a sharp drop in material conductivity is indicated upon further disruption of the π-conjugated network, predominantly governing the charge transport. Particularly, the transition from the Mott variable hopping transport mechanism to the Efros-Shklovsky one is signified. Finally, the impact of rGO chemistry and physics on the electrophysical properties of CPCs with the segregated structure is evaluated. Taken together, our results give a hint at how GO chemistry manifests the properties of rGO and the CPC derived from it, offering compelling opportunities for their practical applications.

Investigation of mechanical properties on functionally graded material reinforced with graphene nanoplatelets for biomedical applications

ABSTRACT This research focuses on the mechanical characterization of FG material graded with Graphene nano-platelets (GPLs) in the transverse direction. Different weight percentages of GPL (0–2 wt. %) were incorporated into epoxy resin for manufacturing the FGM using a simple casting method and the effects were analyzed. This paper aims to enhance the material’s performance, especially focusing on its potential use in biomedical tools. Mechanical tests including assessment on tensile, flexural, impact strength, and microhardness demonstrated substantial improvement in strength and stiffness as compared to other nanocomposite structures. Microstructural analysis using scanning electron microscopy (SEM), Fourier-Transform Infrared Spectroscopy (FTIR), and X-ray Diffraction (XRD) analysis which hint at the strong chemical interaction and physical association of GPL nanofiller with the epoxy resin. Thermal analysis was conducted using the Dynamic Mechanical Analysis (DMA) test, which revealed enhanced thermal stability of the FG specimen with a higher glass transition temperature than other carbon nanofillers mixed in epoxy resin. This is advantageous for the FG material to maintain its glassy state, maintaining safety and reliability during high-temperature medical applications. All these findings indicate that the proposed FG-GPL material possesses the necessary mechanical properties, suggesting that customized nanofiller integration could lead to significant advancements in medical procedures, such as in vivo stomach biopsy treatments, drug delivery systems, etc. The material also meets specific anatomical requirements and reduces the risk of malfunction, thereby ensuring patient safety as justified by current experimental investigations.

Improving the Efficiency of Single Lap Riveted Joints in the Carbon Nanofiller Reinforced Laminated Polymer Composites

Improving the Efficiency of Single Lap Riveted Joints in the Carbon Nanofiller Reinforced Laminated Polymer Composites

Enhancement of electrical conductivity and band gap of epoxy/MWCNT/GNP/glass fibers hybrid materials

Polymer composites containing carbon nanoparticles have attracted considerable attention because of their special functional characteristics. Characterization of optical and dielectric characteristics was done. To comprehend the impact of nanofillers, dielectric characteristics, UV–Vis spectroscopy, XRD, and Fourier transform spectroscopy were employed. The role of carbon fillers on metrics, such as band gap energy, absorption coefficient, and dielectric characteristics of nanocomposites was examined to differentiate between the effects of nanofillers. The AC conductivity is explained following the classical percolation theory. The percolation threshold is discovered to be 1 wt.% of a hybrid system of nanofillers consisting of graphene nanoplatelets (GNPs) and multi-walled carbon nanotubes (MWCNTs). The presence of carbon nanofillers significantly enhances the electrical conductivity of the nanocomposites. The optical band gap energy of nanocomposites was obtained from the Tauc method. The study establishes the relationship between band gap energy and AC conductivity using Tauc’s relation and Jonscher’s power law. The results show that the band gap energy of composites decreases with the addition of hybrid nanofillers, with values observed at 2.65 eV and 2.95 eV, while without fillers of 3.1 eV and 3.05 eV attributed to increased localized states within the bandgap. Composites with nanofillers show an AC conductivity of 1.86 S/m at 1 wt% of nanofillers, compared to 1.52 × 10−6 S/m and 1.09 × 10−6 S/m for composites without nanofillers. The UV–Vis spectra reveal a significant blue shift in the absorption peak when the weight percentage of carbon nanoparticles is increased. The findings of this study point toward the possibilities of the development of novel nanocomposites with enhanced performance for electronics and energy storage.

A comparative study on thermo‐oxidative aging and tribological properties of perfluoroelastomer composites reinforced by different carbon nanomaterials at elevated temperatures: Molecular dynamics simulations

AbstractMolecular dynamics (MD) simulations are employed to assess the effects of diverse carbon nanomaterials on the thermo‐oxidative aging properties and tribological behavior of perfluoroelastomer (FFKM) in high‐temperature environments. In this study, carbon nanofillers such as graphene nanosheets (GNS), carbon nanotubes (CNTs), hydroxyl‐functionalized graphene (OH‐GNS), and hydroxyl‐functionalized carbon nanotubes (OH‐CNTs) are examined. The aging properties of composite systems are characterized by parameters like cohesive energy density and mean square displacement. The constant strain method is utilized to estimate the shear modulus and bulk modulus. Three‐layer friction structures are established to analyze the mechanism of fillers on the tribological behavior of composites by applying shear loads. According to the MD simulation results, the addition of carbon nanofillers enhances FFKM's thermo‐oxidative aging performance at 533 K, increases its bulk and shear moduli, and reduces the coefficient of friction and abrasion rate of each composite at high temperatures. Among the four nanofillers, OH‐CNTs is the most effective in terms of improving FFKM performance. Stronger dipoledipole interactions and hydrogen bonding are introduced into the system by OH‐CNTs, which improves the stability of the filler‐matrix interface and produces stronger interfacial interactions. This work offers theoretical predictions for the design and optimization of carbon nanomaterial and FFKM polymer composites.

Biobased polymer nanocomposites prepared by in situ polymerization: comparison between carbon and mineral nanofillers

Two series based on poly(propylene 2,5-furandicarboxylate)-block-poly(tetramethylene oxide) (PPF-b-F-PTMO) containing carbon and mineral nanofillers that differ in shape (1D and 2D) were synthesized via in situ polymerization. The influence of the addition of the 1D-type nanoparticle, i.e., carbon nanofibers (CNFs) and halloysite nanotubes (HNTs), and the so-called 2D-type, i.e., graphene nanoplatelets (GNPs) and organoclay (C20A), on the properties of a biobased block copolymer was analyzed. The dispersion of nanoadditives in the nanocomposites was determined using a scanning electron microscope (SEM). The thermal properties were studied employing differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The introduction of nanoparticles increased the crystallinity (Xc) and the mean values of tensile modulus (E) of the bionanocomposites. In turn, one observed that the decrease in the limited viscosity number (LVN) was visible along with incorporating nanoadditives. The synthesized polymer bionanocomposites reveal the mechanical properties of elastomers during mechanical testing. Moreover, the good processability of the obtained materials by injection molding combined with the comprehensive ability to change mechanical and thermal properties of PPF-b-F-PTMO by tailoring the type and content of the nanofillers can indicate their possible applications in packaging, automotive, sports, construction, and many other industries.

Composite Materials Based on Polypropylene and Carbon Nanofillers Obtained by in Situ Polymerization

Composite Materials Based on Polypropylene and Carbon Nanofillers Obtained by in Situ Polymerization

A Comparative Study of the Mechanical and Rheological Properties of LDPE Composites with Various Nanocarbon Fillers

A Comparative Study of the Mechanical and Rheological Properties of LDPE Composites with Various Nanocarbon Fillers

Composites of Polylactide with Carbon Nanofillers: Synthesis, Structure, Properties

Composites of Polylactide with Carbon Nanofillers: Synthesis, Structure, Properties

MATERIALS FOR IMPREGNATION OF POROUS METALLIZATION THERMAL SPRAYED ANTICORROSIVE COATINGS OF SUBMERSIBLE OILFIELD EQUIPMENT. Part 2

The use of thermal sprayed coatings in aggressive petroleum fluid is limited due to the presence of porosity in it. When fluid gets into the pores, corrosion processes begin and thereby reduce the protective properties of thermal sprayed coating. The application of impregnating compounds makes it possible to seal open porosity and prevent the penetration of aggressive environments into the metal under the coating, thereby increasing the barrier properties of the coating. Epoxy polymer materials demonstrate high corrosion resistance and are widely used in the oil industry to protect pipeline elements and submersible oilfield equipment during operation. The second part of the article presents both traditional polymer impregnation materials and new compositions with magnetic nanoparticles and nanocarbon fillers (fullerenes, graphene and nanotubes) which, due to the created magnetic field, are evenly distributed throughout the polymer matrix and increase the crack resistance of the matrix. Polymer impregnating materials of both domestic and foreign production based on phenolic, epoxy, acrylic and urethane resins, modes of their application, conditions of their operation and temperature restrictions are considered. The possibility of using existing independent anti-corrosion polymer coatings as an impregnation of metallization thermal sprayed layers is discussed. Their advantages and disadvantages are highlighted. Examples of self-healing polymer matrices are given that are capable of recognizing the onset of corrosion processes and responding by releasing appropriate effective self-healing agents. The possibility of adding inhibitors to the polymer matrix is described, which helps to increase the anti-corrosion properties of the coating and thereby increase the time between failures of equipment. The issue of normative regulation of the use of impregnating compositions in various fields of industry is covered. The main directions of research that need to be carried out to solve the problem of using polymer materials as the most promising impregnating compositions for anti-corrosion thermal sprayed coatings of submersible oilfield equipment have been identified. First of all, it is necessary to reduce the viscosity of polymer resins to increase their penetration into open pores.

Investigation on piezoresistivity of self-sensing cementitious composites containing nano carbon fillers under water content variations

Self-sensing cementitious composites containing nano carbon fillers have extensive application prospects in structural health monitoring (SHM) due to their excellent intrinsic piezoresistivity, good mechanical performances, high compatibility and durability. However, the piezoresistivity is prone to be affected by environmental factors, such as water content. Therefore, it is urgent to study the influence of water content on piezoresistivity to avoid unwanted effect. In the present study, piezoresistivity of self-sensing cementitious composites containing nano carbon fillers under cyclic compression with different water contents is investigated. Moreover, mechanisms are also explored comprehensively. The results indicate that the sensitivity, repeatability and stability of the piezoresistivity deteriorate with decreasing of water content. The maximum FCR and stress/strain sensitivity are decreased from 14.3 % to 4.5 % and 0.72 %·MPa−1/124–0.23 %·MPa−1/39, respectively, when water content decreases from 3.53 % to nearly 0 %. Variation of electrical conductivity pathways and networks caused by enclosed water film on surface of electrical conductive fillers take responsible for the changeable of piezoresistivity with different water content. The outcomes offered validity of self-sensing cementitious composites implementation in SHM withstand variation of water content.

Porous PVDF composites with ultralow percolation threshold for wide-range dynamic and static pressure sensing

Porous conductive polymer composites are very attractive for static pressure sensing due to high sensitivity and good elasticity contributed by the porous structure, while they are hard to detect dynamic pressure. Herein, we report a porous conductive poly (vinylidene fluoride) (PVDF) composite capable of detecting static and dynamic pressure over a pressure range of 0–1 MPa, which was fabricated by melt mixing PVDF, polyethylene oxide (PEO) and carbon nanofillers, followed by etching PEO with water. Such porous PVDF composites have a very low percolation threshold (0.035 wt%) of carbon nanostructures (i.e., branched carbon nanotubes) thanks to the selective distribution of conductive fillers in the pore wall after etching. At the same time, the pore size and porosity of the porous PVDF composites can be tuned by the molecular weight (Mw) and blending ratios of two polymers, leading to the kinetically-tailorable blend morphology for tunable mechanical and electrical properties. The as-fabricated porous PVDF composites with a good combination of mechanical properties and electrical conductivities, which can be used as pressure sensors toward wide-range (0–1 MPa) dynamic and static pressure sensing. Such pressure sensors demonstrate potential applications in detecting the degree of finger bending, distinguishing the walking and running, and monitoring a series of technical movements in playing soccer, i.e., static and dynamic exercises.

Molecular insights into strengthening of biomineral apatite with carbon nanofillers: A simulation study

Biomineral apatite (Ap) has been widely utilized in clinical bone graft procedures for over 25 years. However, its lower tensile strength and fracture toughness compared to natural bone limit its application in large load-bearing systems. This approach aims to enhance the mechanical performance of Ap while preserving its bioactivity, thereby expanding its potential clinical applications. In this study, the creation and processing of carbon nanofiller-based Ap nanocomposites, including pristine and vacancy-defective carbon nanofillers, are investigated using molecular dynamics simulations. The mechanical behaviour of Ap nanocomposites reinforced with three types of carbon nanofillers (CNF) is examined: (i) three-dimensional metallic carbon nanostructure with interlocking hexagons T6B (beam-like), (ii) carbon nanotubes (CNT), and (iii) three-dimensional metallic carbon nanostructure with interlocking hexagons T6P (plate-like). The analysis encompasses detailing the methodology utilized for modelling the equilibrated structures of CNF/Ap nanocomposites, along with the characterization of their elastic parameters. Computational findings reveal the significant impact of CNT chirality, Aspect Ratio (AR) of T6B and orientation of T6P on the mechanical properties of the nanocomposites and observed inclusion of CNF enhances the mechanical properties compared with those of pure Ap. The findings indicate that the lower diameter CNT and smaller cross-sectional area of T6B exhibit higher tensile strength compared to the larger CNT diameter and larger cross-sectional area of T6B of the same length. Further, the analysis highlights the substantial influence of vacancy defects concentration on CNF on the mechanical behaviour of nanocomposites, with an increase in defects correlating to a decrease in the mechanical strength of both CNF and CNF-based nanocomposites.

Statistical analysis to examine the influence of thermal aging on hybrid glass epoxy polymer composites with fillers of multi‐walled carbon nanotubes

AbstractE‐glass fibers are widely preferred due to ease of processing and its low cost, which has substantial scope in the fields of electronics and electrical insulation applications. Because of its low strength and corrosion resistance, use of E‐glass fibers is limited in aerospace and automotive applications. There is a need for enhancing the properties of the composite to overcome such limitations. Therefore, an attempt is made to introduce multi‐walled carbon nanotubes (MWCNT) as fillers into E‐glass fibers to meet the industry needs. In the current study, woven glass fiber of 5 layers and multi‐walled nano carbon fillers of 2, 4 and 6 by wt%, LY556 epoxy resin, and HY951 hardener were used to prepare 4 different type of composites along with the neat epoxy glass fiber reinforced polymer composites (GFRP). The hand‐layup route was used in the composite preparation due to its low cost, technological feasibility, and simple process setup. The developed samples were characterized for mechanical properties via tensile, flexural and impact tests. Tribological characteristics were performed by air jet erosion test. Chauvenet's criterion is applied for identifying the outliers (if any) from the data of repeated test properties. Taguchi's (orthogonal array) is selected for obtaining optimal hybrid composite, which yield better mechanical properties. Empirical relations are developed for the material properties in terms of process variables. The sample (4 wt% MWCNT) exhibited enhancement of 17.27% in tensile strength, 6% of impact strength and 7.3% of flexural strength when compared with neat epoxy GFRP. This hybrid composite is considered for thermal aging and observed at 60°C, 8% increase in tensile, 7% increase of impact and 15% in flexural strength due to the precipitation on carbon nano tubes along the gain boundaries. The present study recommends 4% MWCNT fillers in developing hybrid glass epoxy polymer composites for use in aerospace, automotive and civil construction industries due to economic and technological feasibility.Highlights Utilize low‐cost E‐glass fibers in electronics and electrical insulation applications. Improve composite properties for aerospace and automotive industries. Develop hybrid glass epoxy composites with 2 to 6 wt% MWCNT fillers. Examine wear characteristics under air jet erosion and study the impact of thermal aging on mechanical properties. Apply Chauvenet's criterion for outlier identification in measured properties datasets.

Development of Anisotropic Electrically Conductive GNP-Reinforced PCL-Collagen Scaffold for Enhanced Neurogenic Differentiation under Electrical Stimulation.

The internal electric field of the human body plays a crucial role in regulating various biological processes, such as, cellular interactions, embryonic development and the healing process. Electrical stimulation (ES) modulates cytoskeleton and calcium ion activities to restore nervous system functioning. When exposed to electrical fields, stem cells respond similarly to neurons, muscle cells, blood vessel linings, and connective tissue (fibroblasts), depending on their environment. This study develops cost-effective electroconductive scaffolds for regenerative therapy. This was achieved by incorporating carboxy functionalized graphene nanoplatelets (GNPs) into a Polycaprolactone (PCL)-collagen matrix. ES was used to assess the scaffolds' propensity to boost neuronal differentiation from MSCs. This study reported that aligned GNP-reinforced PCL-Collagen scaffolds demonstrate substantial MSC differentiation with ES. This work effectively develops scaffolds using a simple, cost-effective synthesis approach. The direct coupling approach generated a homogeneous electric field to stimulate cells cultured on GNP-reinforced scaffolds. The scaffolds exhibited improved mechanical and electrical characteristics, as a result of the reinforcement with carbon nanofillers. In vitro results suggest that electrical stimulation helps differentiation of mesenchymal stem-like cells (MSC-like) towards neuronal. This finding holds great potential for the development of effective treatments for tissue injuries related to the nervous system.

Polymer-based LFP cathode/current collector microfiber-meshes with bi- and interlayered architectures for Li-ion battery

In this study, we report the development of a free-standing fiber-based mesh cathode made of electrospun composite microfibers containing 80 wt% lithium iron phosphate (LFP), as well as conductive microfibers containing carbon nano-fillers acting as the current collector (CC). Neither the electrode nor the current collector undergoes post-fabrication treatment or calcination. Scanning electron microscopy confirmed that the meshes are constructed of well-shaped microfibers and exhibit a high porosity, enabling efficient electrolyte penetration and improved electron and ion-transport channels.Two cathode architectures of the LFP/polymer-based CC meshes were explored: bilayered and interlayered. Both architectures are characterized by a high surface-to-volume ratio. The interlayered structure showed superior electrochemical performance due to enhanced LFP-CC fiber-to-fiber contacts and reduced resistance. Comparative analysis with electrospun LFP on aluminum foil revealed comparable specific capacity but higher polarization in the electrospun LFP/CC meshes, attributed to increased internal resistance and limited fiber-to-fiber contacts. However, the electrospun interlayered LFP/CC mesh exhibited significantly higher gravimetric energy density (197 Wh/kg (LFP + CC) and 94 Wh/kg (LFP + Al), respectively), offering lightweight and higher-energy-density electrode materials, thus guiding the design of high-performance flexible lithium-ion batteries.

Nanocarbon/Co3O4/Epoxy Composites for Microwave Shielding and Absorption

The epoxy composite materials (CMs) with a random distribution of nanosized Co3O4 and carbon nanoparticles (graphite nanoplatelets GNP and carbon nanotubes CNT) are fabricated. Complex permittivity, permeability, and shielding properties of composite materials with 30 wt% of Co3O4 and (2–5) wt% of nanocarbon are measured in the frequency range of 1–67 GHz using the transmission–reflection method. A significant increase of microwave permittivity and presence of several peaks on the dependencies of the imaginary part of permittivity on the frequency are found for three‐phase nanocarbon/Co3O4/epoxy CMs. The observed microwave shielding efficiency of three‐phase epoxy composites is enhanced compared to two‐phase nanocarbon–epoxy composites. Such enhancement of shielding efficiency correlates with the increase of DC conductivity of these three‐phase composites. The measured complex permittivity and permeability spectra for nanocarbon/Co3O4/epoxy CMs are used for modeling the reflection loss for studied composites. It is shown that the most preferable for microwave absorption is the composites containing 2 wt% of nanocarbon filler for a sample thickness of 0.5–0.7 mm. The highest reflection loss = 30 dB with an absorption bandwidth of 15 GHz is found for epoxy composite filled with 2 wt% of GNP and 30 wt% of Co3O4 for a sample thickness of 0.5 mm.

Cementitious composites modified by nanocarbon fillers with cooperation effect possessing excellent self-sensing properties

Abstract The safety and durability of concrete structures are prone to damage and result in significant harm to human society. Hence, monitoring and estimating the states of concrete structures is of great significance to protecting human safety. Graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs) are promising candidates to endow cementitious composites with piezoresistivity for the health monitoring of concrete structures. Therefore, the aim of this article is to explore the effect of the hybrid GNPs and CNTs on behavior of cementitious composites with cooperation effects. The cementitious composites containing the hybrid GNPs and CNTs with simplified manufacturing methods are developed first. And then, the mechanical behaviors, electrical conductivities, and piezoresistive performances of the composites are investigated systematically. Finally, the modification mechanisms are also discussed. The results proved that the electrical resistivity of the composites with the hybrid GNPs and CNT concentration of 5.0 wt% is reduced by three orders of magnitudes, and the FCR and sensitivities are reached at 36.0% and 1.1% MPa−1/177.9, respectively. Its compressive strength/elastic modulus is achieved at 73.3 MPa/16.9 GPa. Therefore, the hybrid GNPs and CNTs modified cementitious composite present great potential application in monitoring and evaluating service states of civil infrastructures.

In-depth investigation of how carbon nanofiller dispersion affects microcellular foaming behavior in poly(butylene succinate) nanocomposites

This study explores the impact of carbon nanotubes (CNTs) dispersion on the microcellular foaming characteristics of poly(butylene succinate) (PBS) matrices. Two distinct dispersion methods, primary (PD) and secondary (SD), were employed to fabricate PBS/CNT nanocomposites, resulting in different filler dispersion states. The PD technique involves the conventional method of direct melt blending PBS with CNTs, while the SD technique adopts a more advanced strategy by integrating the Pickering emulsion template with melt blending, achieving finer CNTs distribution within the PBS matrix. The results reveal that the SD technique leads to significantly more uniform distribution of CNTs, which in turn enhances the melt strength and crystallization of the polymer matrix, thereby broadening the window for microcellular foaming. Notably, foams developed through the SD method exhibited a decrease in cell size to 10.4 μm and an increase in cell density to 1.8×1010 cells·cm‐3. Moreover, this uniform distribution of CNTs contributed to superior cell stability and an increase in compressive strength to 14.0 MPa. These findings highlight the pivotal role of nanofiller dispersion in determining foam properties and establish foundational knowledge for designing PBS foams with consistent and uniform cell structures. Such advancements are crucial for enhancing the applicability and performance of PBS-based materials across a spectrum of industries.