High Conductive Composites Research Articles

Multifunctional and high-performance electrothermal films based on carbon black/Ag nanowires/graphene composites

Fabricating high-conductive composites and constructing highly conductive networks are crucial for high-performance electrothermal film. In this study, an Ag nanowires/graphene (Ag/G) composite synthesized by liquid-phase exfoliation and in-situ photoreduction is mixed with carbon black (CB) to form a composite conductive ink, and a CB/Ag/G composite electrothermal film with a point-line-plane three-dimensional microstructure is obtained via blade coating process. Both the addition of Ag nanowires and a subsequent compression rolling treatment induce the establishment of the effective conductive network in the film, endowing it with an outstanding conductivity of 399.4 S cm−1. The film reaches a Ts of 204 °C with an input voltage of 3.0 V, and is successfully applied in water heating and de-icing, demonstrating its extraordinary electrothermal performance and vast potential for practical applications. The film is also used as an electromagnetic shielding film and heat dissipation substrate, showing exceptional electromagnetic shielding (42.5 dB) and heat dissipation properties.

Innovative GQDs and supra-GQDs assemblies for developing high strength and conductive cement composites

Recently, there has been significant interest in using several types of graphene derivatives to enhance the performance of cement composites. There are novel graphene quantum materials called graphene quantum dots (GQDs) in ultrafine scales, and none has been explored in cement materials. This work presents the effects of these two synthesized graphene derivatives (Qds and BC) on the flow, bulk density, permeable void, water absorption, compressive strength, flexural strength, sulphate attack, electrical conductivity, thermal conductivity, and microstructures of cement composites, compared with commercial graphene oxide (GO) and plain mix. The findings show that the composites containing GQDs have excellent fresh, physical, mechanical, and sulphate attack properties. The 1.2% BC composites has the highest compressive and flexural strengths, with 40% and 108% higher than the control, respectively. Moreover, their electrical and thermal conductivity properties increased as a function of GQDs content. The microstructural bridging mechanism regarding the seeding and crystal growth of C-S-H phase were seen. This study offers novel insights into the role of using GQDs in cement composites such that the materials can be used as a high performance, high conductive concrete, which can be a future of the GQDs in the construction industry.

Single‐walled Carbon Nanotubes Dispersed by CO2 Responsive Surfactants for Fabricating High Conductive Epoxy Composites

AbstractThe emerging nanomaterials single‐walled carbon nanotube (SWNTs) with large specific surface area, excellent electrical conductivity and high mechanical strength, has been used to fabricate electronic devices. However, the extremely strong π‐π interactions make SWNTs easy to agglomerate, thus limiting their application. In this work, a novel method was applied to disperse SWNTs by using rigid rosin‐based CO2 responsive surfactant rosin acid dimaleimide choline (R‐BMI‐C). When pH 10.4, SWNTs can be uniformly and stably dispersed, and at pH 6.3, SWNTs aggregated. The dispersed SWNTs was then integrated into diglycidyl ether of bis phenol A (DGEBA) to fabricate high conductive epoxy composites. Their properties were characterized by SEM, TG, high resistivity meters, etc.. The results showed that the modified SWNTs/DGEBA composites obtained an ultra‐low percolation threshold (0.025 wt.%). Compared with the original SWNTs/DGEBA composite, its tensile strength and elastic modulus were enhanced by 17 % and 96 %, respectively, when the SWNTs content was 0.5 wt.%.

Preparation of PEEK-NH2/graphene network structured nanocomposites with high electrical conductivity

Abstract The percolation thresholds of poly ether ether ketone/graphene (PEEK/Gr) composites in most studies are high due to the random distribution of Gr in the matrix. Here, aminated poly-ether-ether-ketone/graphene network (PEEK-NH2/GN) nanocomposites were prepared by electrostatic adsorption of PEEK-NH2 with positive charges and graphene oxide with negative charges, followed by in -situ reduction and hot-pressing. The GN structure of composites was well presented in the images of scanning electron microscope. The PEEK-NH2/GN nanocomposites exhibited excellent electrical conductivity with a maximum conductivity of 0.0634 S·cm−1 and a percolation threshold as low as 0.25 vol%. In addition, the maximum tensile strength of nanocomposites was reached at 93 MPa when the Gr content was 0.5 wt%. We believe that this approach is a new avenue for the production of low filler high conductive polymer composites with potential commercial prospects in various fields.

Constructing segregated structure with multiscale stereocomplex crystallites toward synchronously enhancing the thermal conductivity and thermo-mechanical properties of the poly(l-lactic acid) composites

Based on the rapid development of electronic device performance, heat dissipation has become an urgent problem in packaging materials relating to polymeric composites. Meantime, the severe environmental pollution and energy crisis have also become great problems. Therefore, the development of renewable polymers with high thermal conductivity is a considerable way to reduce the dependence on petroleum-based polymers. Here, we report a convenient method for the preparation of renewable high thermal conductivity composites. Firstly, the stereocomplex crystallites (SCs) granules are prepared through the melt blending of poly(l-lactic acid) (PLLA) and poly(d-lactic acid) (PDLA) at a mass ratio of 1:1. Then, the PLLA/graphene nanoplatelets (PLLA/GNP) composite is coated on the surface of the SC granules by solution blending. Finally, the segregated and double-percolated structures with multiscale SCs form in the PLLA/GNP@SC composites through the compression molding method. The results show that the thermal conductivity of the PLLA/GNP@SC composites are much better than that of the PLLA/GNP composite under the same load of GNPs. The thermal conductivity of the PLLA/GNP@SC composite containing only 2 wt % GNPs reaches 0.96 W m−1K−1, which is 336.4% and 71.4% higher than those of the pure PLLA (0.22 W m−1K−1) and the PLLA/GNP (0.56 W m−1K−1) composite, respectively. The PLLA/GNP@SC composites also exhibit good mechanical properties at high temperatures due to the formed SC microcrystals at the interface between segregated SC granules and continuous PLLA/GNP phase. Moreover, the PLLA/GNP@SC composites also exhibit ultrahigh thermal resistance, flame retardance, and electrical conductivity. This work provides a new way for manufacturing the green multifunctional high thermal conductivity composite.

Effect of Functionalized Multi-Walled Carbon Nanotubes on Preparation of High Strength and Conductive Copper-CNTs Composites by Electrodeposition

Functionalized multiwalled carbon nanotubes (MWCNTs)-reinforced copper (Cu) composites were prepared by the combination of electrowinning and hot-pressing sintering and cold rolling process. The influence of the functionalization of MWCNTs on the strength and electrical properties of MWCNTs/Cu composites was studied. Functional group was introduced to increase the wetting of water electrolytes, improve the poor wettability of MWCNTs and form a highly active surface suitable for the preparation of MWCNTs/Cu composites by electro-deposition, enabling MWCNTs to be evenly dispersed in Cu matrix. Studies have shown that the addition of 1% of functionalized MWCNTs composite can increase the tensile strength by 6% and 165% compared with the addition of unfunctionalized and pure copper. It’s worth noting that the increase of oxygen-containing functional group brought about by functionalized MWCNTs did not significantly reduce the electrical properties of composites. The main reason for this is the good dispersion of the treated MWCNTs in Cu matrix and the bridging for electronic transmission, ensuring that the high electrical properties of MWCNTs/Cu composites are just slightly lower than those of electrolytic pure copper (99.92% IACS).

Filler surface adsorption of mesogenic epoxy for LC Epoxy/MgO composites with high thermal conductivity

Mesogenic epoxies were adsorbed onto the surface of an MgO filler treated with an amino-silane coupling agent and the epoxy-adsorbed MgO filler was dispersed into the liquid crystalline (LC) epoxy matrix resin to develop a high thermal conductivity composite. The effect on the interfacial interaction and the free volume of the LC epoxy composite was investigated by X-ray photoelectron spectroscopy (XPS), X-ray diffractometry (XRD), and positron annihilation lifetime spectroscopy (PALS). The thermal conductivity of the obtained composite (3.16 W/(m∙K)) was remarkably higher than that of the nonadsorbed MgO system (1.93 W/(m∙K)) at almost the same content of 44–45 vol%. This significant improvement of the thermal conductivity can be attributed to the highly ordered structural formation that was induced by the π-π interaction effect of the mesogenic moieties between the adsorbed epoxies and the matrix resin.

A facile ex situ strategy of α-MnS nanoparticles anchored on holey graphene as high-performance anode for lithium-ion batteries

Manganese sulfide (MnS) has been considered as a potential anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity and outstanding electrochemical activity. However, low electronic conductivity and severe volume change of MnS upon lithiation/delithiation hinder its application. Herein, we demonstrate a high conductivity and self-confined MnS composites with holey graphene (hG) sheets (MnS@hG) using ex situ strategy. The MnS@hG anode delivers a high capacity of 870.5 mAh g−1 at 100 mA g−1 after 200 cycles. It also presents a remarkable rate capability of 336 mAh g−1 at the current density up to 5000 mA g−1. The excellent electrochemical performance is attributed to the in-plane pores of the hG, which can reduce the tortuosity of ion diffusion pathway. Compared with graphene, the hG provides more oxygen-containing functional groups that can tightly integrate with the MnS to restrict its volume expansion after cycling. Profiting from these merits, hG can be regarded as a competitive substitution for graphene to combine with MnS as an advanced anode material. This facile ex situ strategy of constructing hG-based composites paves a way for alternative promising electroactive materials in energy storage applications.

Graphite-Filled Polyethylene/Epoxy Blend for High-Conductivity Applications: The Immiscibility Edge

ABSTRACT Polyethylene (PE)/epoxy blends filled with graphite were prepared and studied in this work. The in-plane and through-plane conductivities of the composites increased from 11.68 Scm−1 to 73.11 Scm−1 and 0.20 Scm−1 to 4.12 Scm−1, respectively, as graphite content increased from 30 to 80 wt%. Phase bonding effect of the compatibilizer and reinforcing effect of the filler enhanced the flexural modulus and strength of the composites up to 70 wt% filler content. The electrical conductivities attained by these composites being significantly higher than comparable composite formulations in literature show the edge of immiscible PE/epoxy blend for achieving high-conductivity polymer composites.

High electrical conductive copper matrix composites reinforced with LaB6–TiB2 eutectic particles

In this study, copper matrix composites (CMCs) containing 2.5, 5, 7.5, 15 and 30 wt% LaB6–TiB2 eutectic particles were successfully fabricated by spark plasma sintering technique. Microstructural analysis showed an interaction of LaB6–TiB2 particles with copper matrix which ensures strong adhesion and highly dispersed distribution of reinforcing phase. The influence of the amount of refractory phase on the hardness and electrical conductivity was investigated. An increase in the weight fraction of the reinforcing particles up to 7.5 wt% provides an increase in hardness of threefold compared to that of pure copper, while electrical conductivity was as high as 77 %IACS.

Highly stretchable and sensitive conductive rubber composites with tunable piezoresistivity for motion detection and flexible electrodes

Highly stretchable conductive polymer composites and highly sensitive flexible strain sensors have broad application prospects for wearable electronic devices such as human motion monitoring. In this paper, excellent stretchable and high conductive rubber composites based on room temperature vulcanized (RTV) silicone rubber with carbon fiber (CF) and carbon black (CB) are prepared through the solution method and the ultrasonic dispersion technology. The morphology results show that CF and CB in the composites formed a 3D collaborative conductive network of bridge connection. Then, both the sensitive characteristic and strain-sensing mechanism of CF/CB-RTV silicone rubber sensors have been investigated, which exhibits excellent stretchability as high as 700% and has a good linear relationship with 0–375% strain range and the maximum gauge factor of 182. Also, it has been found that the composites with 12.5 wt% CB maintained good electrical conductivity in the case of large deformation. Finally, CF/CB-RTV conductive composites have been used for human motion monitoring with high sensitivity, and as flexible electrodes in LED bulbs, which still have significant brightness under the 300% strain of the composites with 12.5 wt% CB.

A facile way for fabrication of silver nanoparticle decorated graphene composites

With the fast development of inkjet printing, the fabrication and application of conductive ink have been the frontiers of scientific research. Compared with traditional conductive inks, the rise of graphene also reveals greatly potential applications and attracts many attentions all around the world. In this work, graphene conductive inks with and without Ag nanoparticles were prepared by direct physical methods. Through TEM characterizations, it can be clearly found the resistance of graphene without additional Ag nanoparticles is larger than that of graphene decorated by Ag. Meanwhile, the annealing process also plays an important role in increasing the conductivity of graphene-Ag system. The conductivity obtained in this work follows a rule of σannealed>σwith precursor>σw/o precursor>σpure G. Our work not only offers a reference for exploring high conductive graphene composites but also opens a way for investigating the real mechanism at the interface in graphene composites system.

Injection-molded lightweight and high electrical conductivity composites with microcellular structure and hybrid fillers

Polypropylene/carbon black (PP/CB) and PP/CB/multiwalled carbon nanotube (PP/CB/MWCNT) composites were fabricated by solid and foam injection molding, with the goal of enhancing the electrical conductivity of the composites while decreasing the cost of the final product. The foaming behavior and through-plane (T-P) electrical conductivity of the composites were characterized and analyzed. Cell growth increased the interconnection of the conductive fillers, changed the filler orientation, and enhanced the T-P electrical conductivity of the composites. Under appropriate processing conditions (200°C melt temperature, 70 cm3/s injection flow rate, and 5% void fraction), the T-P electrical conductivity of the foam PP/CB composites was 5 orders of magnitude higher than that of the solid composites (from 5.877 × 10−12 S/m to 1.010 × 10−7 S/m). Moreover, the T-P electrical conductivity values of the PP/CB and PP/CB/MWCNT were compared at the same conductive fillers content (15 wt%). The results showed that the T-P electrical conductivity of the PP/CB/MWCNT composites was far higher than that of the PP/CB composites by almost five orders of magnitude because the MWCNT acted as a bridge between CB particles, and a unique geometric shape was formed in the system. The T-P electrical conductivity of the foam PP/CB/MWCNT composites with 15 wt% carbon fillers was higher than that of the solid PP/CB composites with 20 wt% carbon fillers. This study reveals that the effect of foaming and the addition of hybrid fillers can improve the T-P electrical conductivity of plastic products, which is very important for the development of lightweight conductive plastics.

Electrical and thermal properties of silicone rubber composites filled with Cu-coated carbon fibres and functional carbon nanotubes

ABSTRACTThe thermal and electrical conductivities of SR composites containing Cu-CFs and f-MWNTs were studied. The Cu-CFs and f-MWNTs were prepared by chemical deposition and the coupling method, respectively. Both the fillers were characterised by FT-IR, XRD and SEM and the results showed that the Cu layers were deposited on the surface of the CFs and the MWNTs were successfully modified. In addition, the results of thermal and electrical conductivities for SR composites showed that the hybrid fillers system exhibited a better enhancement on thermal and electrical conductivities for SR composites than the single filler system. The maximum thermal conductivity and the least volume resistivity of SR/Cu-CFs/f-MWNTs composites could reach 3.86 W (m K)−1 and 3.5 × 103 Ω cm, respectively. Based on the experimental results, we recognised the improvement of intrinsical thermal and electrical conductivities of CFs and the good dispersion of MWNTs contributed to the formation of densified 3D conducting networks. Thus, the hybrid fillers system could synergistically enhance the thermal and electrical conductivities of SR composites. We believe, this study could provide an effective way for the design of high conductive polymer composites.

Silver nanowire as an efficient filler for high conductive polyurethane composites

ABSTRACTComposites of silver nanowires (AgNWs) and polyurethane (PU) were prepared and their properties evaluated for potential applications as electrically conducting materials. Polyurethanes were chosen as the base substrate because of their inherent biocompatibility, biostability, excellent processability and good mechanical properties. The composites were prepared with varying content of AgNW by a solvent casting method. The electrical conductivity of the resulting composites was assessed using a 4-probe conductivity method and a maximum conductivity of 352.6 S cm–1 was achieved with 25% AgNW loading. The composite films were then characterised by various techniques to investigate the structure–property relationships. The above-mentioned analyses showed that the composite films retained the tensile and thermal properties of the parent PU while showing excellent conductivity.

Adjustable thermal expansion in La(Fe, Si)13-based conductive composites by high-pressure synthesis

Providing a suitable contact interface, where a high conductivity material with a desirable coefficient of thermal expansion (CTE) adjoins the target micro-electric devices, is very crucial to optimize the properties and service life of the relevant instruments. Regrettably, a high conductivity, low thermal expansion and relatively inexpensive material is very rare. Composites, fortunately, can offer a method to design materials with adjustable properties by mixing two or more diverse constituents. In this paper, high conductivity composites with adjustable thermal expansion were successfully prepared by a high-pressure synthesis. The composites are based on combining La(Fe,Si)13-based compounds, the materials showing a giant, isotropic negative thermal expansion (NTE) properties, within Cu matrix. The La(Fe,Si)13-based compounds were used to adjust the CTE of the composites, while the Cu phase is in charge of tuning the thermal conductivity properties. Thus, by changing the relative amount of the two components, the composites with high conductivities and adjustable CTE were achieved. Furthermore, the thermal expansion and magnetic properties of the composites were investigated by a physical property measurement system. The present results highlight the potential applications of the Cu-based high conductivity composites with room-temperature NTE properties in the thermal contacts to various semiconductor and microelectronic devices.

High conductive aluminium metal matrix composites with carbon inserts obtained by casting processes

This work focuses on the production of high conductive Aluminum based MMC or co-cast components obtained by casting processes. The activity started from the “reinforcement” materials to be used for the MMC fabrication. Carbon based materials were chosen and their characterization under the thermal point of view was carried out. Several arrangements for matrix-reinforcement and matrix-insert couples were evaluated and their potential performances were estimated via numerical simulation. Aluminum-Diamond, Aluminum-Reduced Graphene Oxide and Aluminum-Thermal Pyrolytic Graphite components were produced and their performances were experimentally evaluated. Finally, demonstrator utilizing the novel materials were produced and tested in their relevant working condition.

A mathematical model for predicting conductivity of polymer composites with a forced assembly network obtained bySCFNAmethod

The Spatial Confining Forced Network Assembly, SCFNA, is a promising method for the preparation of high performance electrical conductive polymer composites, CPCs, by constructing a forced assembly conductive network in the polymer matrix. Because the present mathematical models for predicting electrical conductivities of CPCs were derived based on the free assembly of a conductive network, they were not suitable for predicting the electrical conductivities of the CPCs by SCFNA. A mathematical model for predicting the electrical conductivities of CPCs prepared by SCFNA was proposed in this article by introducing a compression ratio based on experimental data of the CPCs of PP/CF fabricated by SCFNA. The proposed model showed a good agreement with the experimental data of electrical conductivities prepared by SCFNA method. POLYM. COMPOS., 40:1819–1827, 2019. © 2018 Society of Plastics Engineers

Excavated carbon with embedded Si nanoparticles for ultrafast lithium storage

Due to their excellent mechanical durability and high electrical conductivity, carbon and silicon composites are potentially suitable anode materials for Li-ion batteries with high capacity and long lifespan. Nevertheless, the limitations of the composites include their poor ionic diffusion at high current densities during cycling, which leads to low ultrafast performance. In the present study, seeking to improve the ionic diffusion using hydrothermal method, electrospinning, and carbonization, we demonstrate the unique design of excavated carbon and silicon composites (EC/Si). The outstanding energy storage performance of EC/Si electrode provides a discharge specific capacity, impressive rate performance, and ultrafast cycling stability.

Manufacturing of high strength aluminium composites reinforced with nano tungsten particles for electrical application and investigation on in-situ reaction during processing

The improvement of strength without compromising the conductivity remains a major issue in developing superior aluminium conductors. This could be addressed by dispersion of nano-sized high melting point elements such as tungsten which has limited solid-solubility in the aluminium matrix. The composites fabricated in this study shows 1.3 times improvement in yield strength, and 2 times increase in UTS. The composites also exhibit superior electrical conductivity compared to other aluminium alloys. Solid-state processing technique was adopted for composite fabrication to avoid thermally activated reaction, between matrix and particles. An unexpected result was the observation of mechanical energy induced interface reaction between aluminum and tungsten during the processing which was not expected at the low processing temperatures. This was confirmed by detailed TEM examination that probed the formation and structure of this new phase. These findings open up newer possibilities toward efficient and scalable manufacturing of high conductive composites with improved strength.