Strategies for chemical modification of graphene and applications of chemically modified graphene

Graphene is emerged as a highly sought after reinforcing filler for epoxy matrix in view of its superior electrical, mechanical and thermal properties. Dispersion of low concentration of graphene can significantly enhance the epoxy/graphene nanocomposites properties. Dispersion of graphene in epoxy matrix depends on processing protocols used, and interfacial interaction between epoxy matrix and graphene. Interfacial interaction between epoxy matrix and graphene can be achieved by covalent and non-covalent modification of graphene. This paper comprehensively review the influence of different processing protocols adopted for the processing of epoxy/graphene nanocomposites, and its effect on mechanical, thermal and electrical properties. In addition, covalent and non-covalent strategies adopted for modification of graphene, and its influence on mechanical, thermal and electrical properties of epoxy/graphene nanocomposites are extensively discussed. The future challenges associated with graphene reinforced epoxy nanocomposites processing have been discussed.

State-of-the-art advancements in studies and applications of graphene: a comprehensive review

Carbon nano-onions (CNOs) have emerged as a very interesting class of carbon nanomaterial with special mechanical, thermal, and electrical properties. The special concentric shell structure, large surface area, and high conductivity give them good prospects in enhancing the performance of polymer nanocomposites. In recent years, CNO-based polymer nanocomposites have been developed with great potential for different applications, such as energy storage, sensors, biomedicine, and advanced structural materials. This chapter discusses the recent development in synthesis, characterization, functionalization, and application of CNOs. Innovative strategies of covalent and non-covalent surface modification have significantly improved the electrical, mechanical, and thermal properties of the nanocomposites. Furthermore, hybrid approaches through combination with other nanofillers have expanded their functionality. Despite such progress, the scalable production of high-quality CNOs with homogeneous distribution within polymers remains a challenge. Long-term stability, environmental impact, and cost efficiency of such materials also largely require further research. This chapter summarizes the state of the art for CNO-based polymer nanocomposites and highlights the most important research directions that need to be pursued to overcome existing challenges and to move closer toward wider adoption of such advanced materials in industrial and commercial applications.

Fullerene has been acknowledged as a significant nanocarbon nanofiller enhancing the imperative polymer characteristics. Since, thermoplastic polymers constitute a large group of polymeric materials, fullerene has been used as reinforcement in these matrices mostly via non-covalent means. This state-of-the-art review article summarizes thermoplastic polymer nanocomposites reinforced with fullerene nano-additives without involving any covalent interactions. Accordingly, thermoplastic polymer/fullerene nanocomposites of interest have non-covalent or physical interactions in the matrix-nanofiller such as van der Waals forces, electrostatic interactions, hydrogen bonding, and aromatic stacking interactions. Number of thermoplastic polymers including polyamide, polyurethanes, and block copolymers have been non-covalently or physically reinforced with the fullerene molecules. Ensuing high performance thermoplastic polymer/fullerene nanocomposites exhibited improved microstructure, electrical, mechanical, thermal, and other physical properties. Enhancements in the thermal, mechanical, and electrical properties of the thermoplastic/fullerene nanomaterials were found dependent upon the nanofiller contents, orientations, interfacial effects, and processing. Consequently, the polyamide/fullerene systems were found efficient to enhance the glass transition up to 260°C, in addition to optimum mechanical properties. Polyurethane/fullerene systems performed better for improved tensile strength and young’s modulus features up to 90 MPa and 48 GPa, respectively. System based on poly (methyl methacrylate) and fullerene has resulted in high thermal degradation temperature in the range of 501-633°C with fine electrical conductivity of 1.3 Scm−1. Using combination of fullerene and graphene nanofiller (due to synergistic effects) has been found to improve the electrical conductivity considerably in the range of 1.8–2.5 Scm−1 for a polystyrene and block copolymer system. However, attaining fine fullerene nanoparticle dispersion of non-covalently reinforced matrices have been found important affecting the final nanocomposite properties. Consequently, processability and essential characteristics of non-covalently fullerene filled nanocomposites can be influenced due to nanoparticle aggregation. Hence, the physical property enhancement potential of physical linking between the non-covalently linked thermoplastics-fullerene has been portrayed in this article. Research on non-covalently interacted thermoplastic polymer/fullerene nanocomposites revealed technical potential ranging from energy/electronic devices to engineering and biomedical sectors. This review article can be a useful guide for the field researchers towards the development of advanced systems using non-covalently linked polymer/fullerene nanomaterials for future technical applications.

The global requirement to mitigate environmental challenges demands a paradigm shift towards sustainable materials. Forest-based products, primarily derived from wood, present a promising path due to their abundance and renewability. However, enhancing their properties to meet modern demands remains a challenge. This review article, the first of its kind, explores the transformative potential of incorporating graphene and graphene-based nanomaterials into forest-based products to overcome the challenges associated with mass-scale applications. Graphene, a two-dimensional carbon nanomaterial, has emerged as a multifunctional additive with exceptional mechanical, electrical, and thermal properties. Functionalization of graphene through covalent or non-covalent modifications has emerged as a key strategy to tune its characteristics and expand its utility across different domains. Recent studies highlight its promising role in forest-derived products, including coatings, composites, adhesives, and lignocellulosic substrates. Graphene and its derivatives, such as graphene oxide, reduced graphene oxide, and graphene nanoplatelets, have been shown to enhance barrier properties, mechanical strength, fire retardancy, and environmental resistance, while also reducing volatile organic compound emissions through formaldehyde scavenging. Moreover, graphene-coated forest-derived substrates demonstrate potential for applications in energy storage, smart sensors, and multifunctional green devices. This review compiles recent advances in integrating graphene with wood and lignocellulosic materials to address the urgency and potential of this innovative approach towards a more sustainable future. It also discusses the practical challenges in applying graphene, thereby providing a comprehensive perspective for its future research and industrial applications.

In this study, the electrical, thermal, and mechanical properties of hybrid natural fiber composite are taken under consideration. Fly ash waste is used as the filler material. Unsaturated polyester resin is used as the matrix material to bind the composite. Alkali-treated Phaseolus vulgaris fiber (PVF) (5% NaOH for 45 min) is taken as the primary filler. Nanosilica synthesized is added to the composite samples at a constant percentage (1%). Samples of various weight percentages are prepared (2%, 4%, 6%, 8%, and 10% of PVF) and studied. Dielectric strength test for electrical property, thermal conductivity test for the thermal property, mechanical tests like tensile strength, Brinell hardness, Izod impact tests, and water absorption test are also taken under consideration. The composite showed a regular increasing trend in mechanical and electrical properties with varying weight percentages until 6% PVF; afterward, a decreasing trend in the mechanical and electrical properties of the composite was found with greater weight percentages. Whereas for thermal conductivity and water absorption tests, the results showed a regular decreasing trend until 6% PVF; afterward an increasing trend was found. It is found that the composite of 6% PVF and 1% SiO2 shows better electrical, thermal, and mechanical properties.

At the moment, we are standing at the edge of exploring conducting nanofillers-based polymer composites and their multifunctional applications which changed the modern science in new direction. Among the several nanofillers, two-dimensional graphene sheet changes the scientific research in new angle with huge applications. The excellent electrical, thermal, and mechanical properties of graphene and their derivatives play a most important role in different fields of applications and increased its demand in modern science. Here, basically, we have looked out various applications of graphene, history of graphene, effectiveness of graphene, and its various derivatives in modern science. The properties of graphene also depend on modification of graphene; it can be chemical modification or physical modification.

In the present study, attempts were made to manufacture innovative conducting polymer nanocomposites (CPCs) with high performance, low cost, and appropriate electrical, mechanical, and thermal properties. However, one of the main challenges in creating CPCs is the tendency of nanofillers to agglomerate and accumulate, resulting in a decrease in the electrical properties and performance of CPCs. To address this issue, the study developed an efficient and eco‐friendly CPC using carboxymethyl cellulose (CMC) as a binder and carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) as nanofillers. The study employed a chemical functionalization method to modify CNTs and enhance their compatibility and dispersion properties in the CMC matrix. The prepared CPCs were characterized using various techniques, including Fourier‐transform infrared spectroscopy, x‐ray diffraction, and field emission scanning electron microscopy. The results showed an improvement in homogeneity and surface cohesion between CMC and O‐CNTs through chemical surface modification of CNTs via carboxylic acid functional groups. The study observed good dispersion of nanofillers without any aggregation of the CMC/GNP/O‐CNT compared with the nontreated CMC/GNP/CNT composite. While a decrease in the degree of crystallinity was observed, conductivity increased for the CPC containing oxidized CNTs. The study found that the highest conductivity of ~112 S/m was obtained for D‐CMC/GNP/O‐CNT with 25 wt% of O‐CNT, while the maximum conductivity of D‐CMC/GNP/CNT was ~80 S/m with 35 wt% of CNTs. Additionally, the study observed an improvement in electrochemical properties after treatment of CNTs in the form of higher cathodic current in cyclic voltammetry and lower charge transfer resistance in impedance spectroscopy of D‐CMC/GNP/O‐CNT35 compared to untreated one. Highlights Preparation of new conductive nanocomposite consisting of CMC, CNTs, and GNPs. Carboxylation of CNTs to improve O‐CNT and CMC intermolecular interaction CMC/GNP/O‐CNT is 40% more conductive than unmodified CNT nanocomposite. Higher thermal stability and mechanical properties were observed by using O‐CNT. O‐CNT caused higher current density and lower electron transfer resistance for CPCs.

Polyimides (PI) are a class of dielectric polymer used in a wide range of electronics and electrical engineering applications from low-voltage microelectronics to high voltage isolation. They are well appreciated because of their excellent thermal, electrical, and mechanical properties, each of which need to be optimized uniquely depending on the end application. For example, for high-voltage applications, the final polymer breakdown field and dielectric properties must be optimized, both of which are dependent on the curing process and the final physico-chemical properties of PI. The majority of studies to date have focused on a limited set of properties of the polymer and have analyzed the effect of curing from a physicochemical-, mechanical- or electrical-centric viewpoint. This paper seeks to overcome this, unifying all of these characterizations in the same study to accurately describe the universal effect of the cure temperature on the properties of PI and at an industrial processing scale. This paper reports the widest-ranging study of its kind on the effect that cure temperature has on the physico-chemical, mechanical, thermal and electrical properties of polyimide, specifically poly (pyromellitic dianhydride-co-4, 4′-oxydianiline) (PMDA/ODA). The optimization of the cure temperature is accurately studied not only regarding the degree of imidization (DOI), but also considering the entire physical properties. Particularly, the analysis elucidates the key role of the charge–transfer complex (CTC) on these properties. The results show that while the thermal and mechanical properties improve with both DOI and CTC formation, the electrical properties, particularly at high field conditions, show an antagonistic behavior enhancing with increasing DOI while degrading at higher temperatures as the CTC formation increases. The electrical characterization at low field presents an enhancement of the final PI properties likely due to the DOI. On the contrary, at high electric field, the conductivity results show an improvement at an intermediate temperature emphasizing an ideal compromise between a high DOI and PI chain packing when the thermal imidization process is performed over this equilibrium. This balance enables maximum performance to be obtained for the PI film with optimized electrical properties and, overall, optimal thermal and mechanical properties are achieved.

High temperature processing thermoplastic polymers, polyetheretherketone (PEEK) and polyethersulphone (PES), were melt blended with carbon fibers (CFs) to make composites. These composites were investigated for their mechanical, thermal, and electrical properties. Mechanical properties that are expressed in terms of storage modulus, loss, and damping were enhanced with the addition of CFs. Thermal properties were determined by DSC and TGA. These methods help to understand the effects of fiber content and fiber–matrix adhesion in the composites. Composites were also tested for their electrical and thermal conductivity because CFs leave the composites thermally and electrically conductive. CFs enhanced the crystallinity of the PEEK appreciably that in turn influenced thermal conductivity, electrical resistivity, and the stiffness of PEEK/CF (composites of PEEK with CFs). PES/CF (composites of PES with CF) shows a different behavior due to the amorphous nature of PES. The work involves one filler and two different matrices, and so it provides an interesting comparison of how matrix morphology can influence the properties of composites. POLYM. COMPOS. 28:785–796, 2007. © 2007 Society of Plastics Engineers.

Intrinsically Viscoelastic Supramolecular Conjugated Polymer toward Suppressing Coffee-Ring Effect

Carbon fiber-reinforced particulate composites are immensely used in commercial and military applications due to their excellent functional and mechanical performance. Several studies have been reported to use nanofiller in carbon fiber-reinforced composites to improve their functional and mechanical performance. However, a comparative study was required to depict the best dielectric and magnetic nanofillers with excellent functional and mechanical performance. The current research was performed to compare the effect of different dielectric and magnetic nanoparticles on the electrical, mechanical, and thermal properties of carbon fiber-reinforced composites. The objective was to identify a nanofiller with excellent electrical, mechanical, and thermal properties with the same weight ratio and a potential candidate for EMI shielding application. Unidirectional composite prepregs containing 2% (by weight) of each magnetic and dielectric nanofillers were fabricated on an in-house developed lab-scale UD prepreg manufacturing setup. Among the dielectric nanofillers, the composite samples containing MWCNT nanofiller showed the highest electrical, thermal, and mechanical properties. The composite samples containing titanium oxide nanofillers showed better flexural, electrical, and thermal properties among magnetic nanofillers.

Thermal, mechanical and electrical properties of hard B4C, BCN, ZrBC and ZrBCN ceramics

Mechanism of Ga2O3 addition on the enhancement of electrical and mechanical properties of ZnO based varistor

Hybrid combination of carbon fillers is utilized in an epoxy matrix to enhance DC/AC conductivity and dielectric constant. Influence at electrical percolation on mechanical strength, thermal stability, co‐efficient of thermal expansion (CTE), and flame properties have been investigated since proper balance of the properties is critical. Multiwalled carbon nanotube and graphene nanoplatelets of different weight proportions are incorporated in epoxy matrix to understand their impact of electrical, mechanical and thermal properties. It is observed that weight fraction of the carbon fillers at electrical percolation tends to deteriorate the mechanical and flame properties, minimally influences thermal stability while decreasing the CTE. The weight fractions below the electrical percolation are observed to enhance mechanical and flame properties as compared to percolation level. Though the formation of network of carbon fillers is responsible for enhancement of electrical conduction and CTE, the synergy of carbon fillers is not evident in mechanical and flame properties due to dominating influence of aspect ratio, orientation, and alignment. DC conductivity of 3 × 10−6 S/m, AC conductivity of 4 × 10−2 S/m at 8 MHz is observed at electrical percolation. However, composite reveals 5% to 10% reduction in mechanical strength, while the thermal stability and glass transition (126°C) are minimally affected at percolation. Co‐efficient of thermal expansion improves to 2 × 10−6/°C and heat deflection temperature increases to 140°C. Flame properties reveal divergent trends. The need for proper balance of electrical, thermal and mechanical properties at electrical percolation is emphasized.