Conductivity Of Composite Materials Research Articles

High thermal conductivity composite phase change material with Zn2+ metal organic gel and expanded graphite for battery thermal management

Phase change materials (PCMs) with promising potential thermal energy is stored and released much thermal energy during phase change process, which has greatly prospect in building energy conservation, waste heat recovery, energy storage, electrical vehicles (EVs) and other fields. Nevertheless, the low thermal conductivity and easy leakage of PCM is still a challenge to restrict its fasting development. Traditional supporting material is hard to reconcile antileakage and thermal conductivity of composite PCM (CPCM). Herein, the polyethylene glycol (PEG) with three-dimensional Zn2+ metal–organic gel (ZnHGL) as high-thermal conductivity support framework, styrene–butadiene–styrene block copolymer (SBS) and expanded graphite (EG) has been designed and prepared PZSE with high thermal conductivity, accompany with double transferring heat and supporting network structure. In contrast with pure PEG, the thermal conductivity of PZSE2 is increased by obvious 8.7 times when Zn2+ metal–organic gel and SBS with the proportion of 1:1, the mass maintenance rate and latent heat storage capacity are increased to 99.5 % and 103.64 J/g, respectively. Further, the thermal imaging camera indicate that PZSE2 exhibit a stable temperature-regulation property, which is benefited to extend the time to adjust the temperature. Additionally, the maximum temperature and temperature differential of the battery module with PZSE2 can be maintained within 60 °C and 6 °C, respectively, even at 1.5C discharge rate after ten cycling process. It indicates that the battery module with PZSE2 has optimum thermal management effect. Therefore, PZSE with metal–organic gel and EG can provide a promising candidate utilization in thermal regulation of EVs and energy storage.

Thermal Management System with Intrinsically High Thermal Conductive and Antileakage Composite Phase-Change Materials for Battery Module

Thermal Management System with Intrinsically High Thermal Conductive and Antileakage Composite Phase-Change Materials for Battery Module

Preparation of high thermal conductivity vat photopolymerization used UV-curable resin synergistically enhanced by silicon nitride and boron nitride

Additive manufacturing (3D printing) technologies, especially vat photopolymerization (VPP), provide a cost-effective and efficient approach for the fabrication of heat dissipation devices with complex geometric designs. The incorporation of inorganic thermal conductive fillers into resin matrix is widely recognized as an effective way to enhance thermal conductivity. Notably, the synergistic effect of hybrid fillers can further enhance thermal conductivity. However, the consequent drastic increase in viscosity of the UV-curable resin may decrease the success rate and accuracy of printing on commercial VPP 3D printers. In this work, hexagonal boron nitride (h-BN) platelets and spherical h-BN together with β-Si3N4 are introduced into the UV-curable resin system. Corresponding results proved that h-BN together with β-Si3N4 provide a synergistic effect on the thermal conductivity enhancement compared to the filler in single morphology only. Moreover, owing to the spherical structure, low-viscosity UV-curable resin with high solid content can be prepared. In specific, a thermal conductive polymer composite material with a solid content of 60 wt% is prepared, which exhibits high thermal conductivity (1.42 W/mK), representing an enhancement of up to 610 % compared to neat resin. In subsequent application demonstrations, 3D printed heat dissipation devices with as-prepared resin composite material have been shown to effectively enhance the heat dissipation rate for the heating device.

Effect of microcarbon particle size and dispersion on the electrical conductivity of LLDPE-carbon composite

This experimental research aimed to develop a conductive polymer composite (CPC) material for electromechanical devices. The composite was made by incorporating conductive micro carbon derived from rice husks into a Linear Low-Density Polyethylene (LLDPE) polymer matrix using hot compaction. Variations of filler composition were used, with carbon loading of 50%, 45%, and 40%, and mesh sizes of #150, #200, and #250. The experimental results showed that particle size variations did not significantly affect composite density, but higher mesh selection improved filler dispersion within the matrix, resulting in higher electrical conductivity values. The optimal conductivity value of 9.43E-04 S/cm was achieved with a micro-carbon composition of 50% loading. However, decreasing micro carbon loading had a more significant impact on reducing electrical conductivity values.

Preparation of functionalized boron nitride nanosheets by one-step method for improving the thermal conductivity of polymers

Boron nitride nanosheets (BNNSs) with high thermal conductivity (TC) have promising applications in the thermal conduction. However, the preparation of BNNSs is cumbersome and BNNSs are prone to aggregation in the polymer matrix, which reduces the efficient enhancement for the TC of BNNSs/polymer composite. Herein, we propose a one-step method for the simultaneous exfoliation and functionalization of BNNSs with polymer latex as an agent. The obtained WPU-BNNSs displayed as few-layers with sizes of 100-500 nm and were mixed with WPU matrix as filler. The results demonstrated that the BNNSs/WPU composites have higher TC than the h-BN/WPU with the same filler content. When the filler content reached 50%, its TC was 251.4% higher than that of pure WPU. The excellent TC arose from the outstanding dispersion uniformity of WPU-BNNSs in the matrix. This study provides an economical and efficient method of fabricating BNNSs-based thermal conductive composite materials.

The multifunctional flexible conductive viscose fabric prepared by thiol modification followed by copper plating

Based on the current rapid development of electronic products, the development of light-weight, processable, environmentally friendly, long-life, durable, less corrosive, and tunable conductive composite materials with multiple applications may be the development direction of next-generation electronic devices. In this work, for the first time, we employed 3-Mercaptopropyltrimethoxysilane (3-MT) to modify viscose nonwovens and enhance the copper plating process. The prepared samples were characterized by Fourier transform infrared, Wide-angle X-ray diffraction (WAXD), scanning electron microscope + energy dispersive X-ray spectroscopy (SEM + EDS), thermogravimetric analysis (TGA), electrical resistivity, anti-corrosion, Joule heating, and electromagnetic interference (EMI) shielding. Results showed that 3-MT was covalently bound to the viscose surface through hydrolysis and condensation reactions and introduced SH groups. WAXD confirmed that the thiol modification did not change the internal crystal structure of viscose and copper ions. TGA and surface morphology analysis confirmed that the modified viscose promoted the deposition of metal particles in the copper plating process due to the affinity of thiol to metal so that copper particles almost completely wrapped the viscose fibers. In addition, 3MT@Cu@Viscose exhibits extremely low surface and volume resistivity (346.6 and 333.2 mΩ·m), improved corrosion resistance (corrosion rate reduced by 58% compared to the unmodified sample), fast Joule heating response (within 10 s) in low voltage (1 V) and excellent EMI shielding effectiveness (EMI SE > 50 dB). It showed great potential in future multi-functional electronic products such as electric heating sensors, smart clothing, and EMI shielding barrier.

High thermal conductivity composite phase change material with nano-Ag particles modified diatomite and expanded graphite for improving battery thermal management efficiency

Composite phase change materials (CPCMs) with significant amounts of latent heat can absorb and release at a constant transition temperature have attracted much attention in energy storage and electrical vehicles fields. Nevertheless, it is still a great challenge to utilize in battery thermal management system owing to low thermal conductivity and liquid leakage. Although many efforts have endeavored to improve transferring heat capacity, the thermal conductivity of CPCM is still need to explored. Herein, a novel high thermal conductivity and anti-leakage CPCM including polyethylene glycol, nano-Ag particles modified diatomite and expanded graphite (PDAE) has been designed and prepared. And the nano-Ag particles have evenly attached to the surface of diatomite through in-situ chemical reduction reaction and self-assembly technology. The experimental results indicate that PDAE exhibits excellent thermal conductivity with 1.91 W∙m−1∙K−1 owing to three-dimensional heat transferring network constructed by nano-Ag particles and expanded graphite. Moreover, it is no shape variation and leakage of PDAE under continuously heated at 60 °C for 2 h. In addition, the temperature performance of battery modules with the different CPCMs have been compared in detail, the results demonstrates that battery module with PDAE can be maintained below 53 °C and the temperature difference is effectively controlled within 5 °C even at 3C discharging rate after 10 cycles. With these prominent performances, this designed CPCM with high thermal conductivity will offer a promising insight into the passive thermal management system in practical application.

Vitrimer Nanocomposites for Highly Thermal Conducting Materials with Sustainability.

Vitrimers, as dynamic covalent network polymers, represent a groundbreaking advancement in materials science. They excel in their applications, such as advanced thermal-conductivity composite materials, providing a sustainable alternative to traditional polymers. The incorporation of vitrimers into composite fillers enhances alignment and heat passway broadly, resulting in superior thermal conductivity compared to conventional thermosetting polymers. Their dynamic exchange reactions enable straightforward reprocessing, fostering the easy reuse of damaged composite materials and opening possibilities for recycling both matrix and filler components. We review an overview of the present advancements in utilizing vitrimers for highly thermally conductive composite materials.

Enhanced thermal conductivity in boron nitride incorporated polyethylene/polymethyl methacrylate composites via double percolation structure

AbstractDue to the miniaturization, integration and multi‐functional development of contemporary electronic devices, there is a growing need for efficient thermal conductive composite materials. This study focuses on enhancing the dispersion of modified boron nitride (mBN) within a linear low‐density polyethylene (LLDPE) phase by incorporating LLDPE‐graft‐Aminomethylpyridine (LLDPE‐g‐Py) to non‐covalently modify BN. Additionally, polymethyl methacrylate (PMMA) and LLDPE polymers were introduced to create modified BN/LLDPE/PMMA (mBN/LLDPE/PMMA) composites with a double percolation structure. The co‐continuous structure of the polymer composites was observed by using scanning electron microscopy (SEM). By selectively locating the BN modified by LLDPE‐g‐Py within the LLDPE phase, the co‐continuous structure of the LLDPE/PMMA blend was upgraded to a double percolation structure. This double percolation structure establishes a dense and optimal heat transfer network within the polymer matrix. The thermal conductivity of the mBN/LLDPE/PMMA composite with BN loading of 40 wt% was significantly increased to 1.12 Wm−1 K−1, which was 350% higher than that of pure LLDPE, 38% higher than that of the BN/LLDPE composite, and 17% higher than that of the BN/LLDPE/PMMA composite. This study offers valuable insights into non‐covalent modification techniques for BN and the design of double percolation structures in thermal conductive polymer composites.Highlights The double percolation structure was successfully constructed by simple melt blending method with LLDPE and PMMA as matrix and BN as thermal conductive filler. The double percolation structure can significantly promote the efficiency of heat transfer inside the thermal conductive composites. A novel non‐covalent modifier LLDPE‐g‐Py was prepared to modify the surface of BN, and the selective localization of modified BN (mBN) in the LLDPE phase was realized.

Enhanced thermal and electrical conductivity in epoxy nanocomposites via liquid crystal-driven alignment of graphene

There is a lack of systematic research on the use of liquid crystal-modified graphene in the production of thermally conductive composites. In this work, we utilized covalent and non-covalent interactions between 4′-allyloxy-biphenyl-4-ol (AOBPO) and graphene oxide (GO), reduced graphene oxide (rGO), and high-temperature reduced graphene oxide (GNS) to improve the compatibility and dispersion of the fillers with the silicone-cycloaliphatic epoxy resin. The thermal conductivity of GNS-AOBPO composite material significantly increases when a shear force field is applied, even at a lower filler content of 7 wt%, reaching 0.828 W/(m·K), which is 1.8 times higher than that without the field. At 9 wt% filler content, the thermal conductivity further increases to 1.161 W/(m·K), which is 10 times higher than epoxy resin. Concurrently, the electrical resistivity decreased by half. This provides a method for preparing thermal conductive composite materials by inducing the orientation of graphene through the application of a shear force field.

Application of Plasma Surface Modification and Slide-ring Polymer Networks for Development of Thermally Conductive Composite Materials

Application of Plasma Surface Modification and Slide-ring Polymer Networks for Development of Thermally Conductive Composite Materials

Electro-Codeposition of Composite Materials for Enhanced Thermal and Electrical Properties

State of the art cryocoolers, high powered electronic systems, semiconductor backplanes, and space platforms require next generation high conductivity composite materials that can reduce product weight while improving performance. To meet this need, Faraday Technology with the help of Universities, National Labs, and industrial partners is developing a scalable electro-codeposition method to produce high conductivity hybrid graphene/copper composite materials. Specifically, this talk will highlight two activities ongoing at Faraday and demonstrate the feasibility of fabricating either composite or laminated graphene-copper hybrid foils or direct printed composite nanowires via a pulse electro-codeposition approach. These activities indicated these composite materials can achieve a greater than 50% reduction in sheet resistance, a ~50% increase in mechanical strain, and a 100% increase in thermal conductivity compared to Cu foils. We will also discuss the opportunity to produce a wide range of material shapes by enabling a direct print apparatus that combines x,y,z control methods with an electro-codeposition printhead. If successful we envision that method to print next generation composite materials like ‘covetics’ that have the potential to meet many of the electronics and space community’s needs by enabling in space structural repairs, fabrication of new electronic components or sensors, or be utilized as heat exchanger composite materials. Finally, this activity also identified commercial partners interested in integrating these next generation into high powered electronics like laser diodes or invertors for electric vehicles.Acknowledgements: Faraday Technology acknowledges the Department of Energy and NASA SBIR activities under Contract No. DE-SC0021676 (DOE Phase II) and 80NSSC22CA099 (NASA Phase II).

In-situ growing of helical carbon fibers on graphene for high-performance flexible strain sensor

Flexible strain sensors have broad applications in the field of human health monitoring. It is essential to design and manufacture sensors with high sensitivity and stability. The aim could be achieved by constructing multi-level interface structure with non ohmic contact in the flexible three-dimensional conductive network. In this paper, helical carbon fibers (HCF) were grown in situ on the surface of 2D sheet material graphene. The prepared composite conductive material GO/HCF has an excellent 3D structure, significantly enhancing the sensor's sensitivity. PDMS and NH4HCO3 encapsulated strain sensor (GO/HCF/N) has GF values of up to 622.8. Besides, the sensor exhibits unique sensing characteristics that other sensors do not have: under low strain conditions, the resistance of the sensor increases with the increase of deformation, and when the deformation exceeds a certain value, the resistance decreases instead. Therefore, GO/HCF/N sensor has a shallow detection limit (0.1 %) and works steadily after 1000 times tensile release cycles. This flexible strain sensor can quickly and accurately identify different human movements in human health monitoring.

Flexible Piezoresistive Polystyrene Composite Sensors Filled with Hollow 3D Graphitic Shells.

The objective of this research was to develop highly effective conductive polymer composite (CPC) materials for flexible piezoresistive sensors, utilizing hollow three-dimensional graphitic shells as a highly conductive particulate component. Polystyrene (PS), a cost-effective and robust polymer widely used in various applications such as household appliances, electronics, automotive parts, packaging, and thermal insulation materials, was chosen as the polymer matrix. The hollow spherical three-dimensional graphitic shells (GS) were synthesized through chemical vapor deposition (CVD) with magnesium oxide (MgO) nanoparticles serving as a support, which was removed post-synthesis and employed as the conductive filler. Commercial multi-walled carbon nanotubes (CNTs) were used as a reference one-dimensional graphene material. The main focus of this study was to investigate the impact of the GS on the piezoresistive response of carbon/polymer composite thin films. The distribution and arrangement of GS and CNTs in the polymer matrix were analyzed using techniques such as X-ray diffraction and scanning electron microscopy, while the electrical, thermal, and mechanical properties of the composites were also evaluated. The results revealed that the PS composite films filled with GS exhibited a more pronounced piezoresistive response as compared to the CNT-based composites, despite their lower mechanical and thermal performance.

Performance of thermally conductive NR composites reinforced with stearic acid‐modified microcrystalline cellulose: A combined experimental and molecular dynamic simulation study

AbstractWith the increasing environmental requirements for improving products and materials using renewable and sustainable resources, cellulose has been seen as one of the most attractive and promising alternatives to traditional inorganic fillers. We developed a new modification method to improve the interface compatibility between natural rubber and sisal cellulose, to improve the mechanical and thermal conductivity properties of rubber composite. Microcrystalline cellulose (MCC) was extracted from sisal cellulose and then the hydrophobic cellulose (SA‐MCC) was prepared by grafting stearic acid on the surface of MCC. MCC and SA‐MCC were added to the thermal conductivity composite material composed of natural rubber and boron nitride. The results showed that the thermal conductivity and tensile properties of the natural rubber composites increased by 17.3% and 20%, respectively, under the addition of 1.8 wt% SA‐MCC. Furthermore, the interfacial interaction between the components in the composite was studied by molecular dynamics simulation. The solubility parameters, free volume fraction, and molecular binding energy were calculated to verify the effectiveness of the modification. This work is expected to provide a theoretical basis for the design and preparation of high‐performance natural rubber composite materials.Highlights Cellulose microcrystals were successfully extracted from sisal fiber and modified. Through the combination of boron nitride and the modified cellulose microcrystals, the thermal conductivity and tensile properties of thermal rubber were successfully improved synchronously. A reasonable molecular simulation model was established to analysis the strengthening mechanism from the microscopic point of view. The molecular simulation conclusions on interface enhancement are in good agreement with the experimental properties.

Universal Approach to Integrating Reduced Graphene Oxide into Polymer Electronics.

Flexible electronics have sparked significant interest in the development of electrically conductive polymer-based composite materials. While efforts are being made to fabricate these composites through laser integration techniques, a versatile methodology applicable to a broad range of thermoplastic polymers remains elusive. Moreover, the underlying mechanisms driving the formation of such composites are not thoroughly understood. Addressing this knowledge gap, our research focuses on the core processes determining the integration of reduced graphene oxide (rGO) with polymers to engineer coatings that are not only flexible and robust but also exhibit electrical conductivity. Notably, we have identified a particular range of laser power densities (between 0.8 and 1.83 kW/cm2), which enables obtaining graphene polymer composite coatings for a large set of thermoplastic polymers. These laser parameters are primarily defined by the thermal properties of the polymers as confirmed by thermal analysis as well as numerical simulations. Scanning electron microscopy with elemental analysis and X-ray photoelectron spectroscopy showed that conductivity can be achieved by two mechanisms-rGO integration and polymer carbonization. Additionally, high-speed videos allowed us to capture the graphene oxide (GO) modification and melt pool formation during laser processing. The cross-sectional analysis of the laser-processed samples showed that the convective flows are present in the polymer substrate explaining the observed behavior. Moreover, the practical application of our research is exemplified through the successful assembly of a conductive wristband for wearable devices. Our study not only fills a critical knowledge gap but also offers a tangible illustration of the potential impact of laser-induced rGO-polymer integration in materials science and engineering applications.

Development of electrically conductive wood‐based composites using carbon nets

AbstractA novel conductive composite material was developed using woven carbon nets. For this purpose, carbon nets with different mesh sizes of 25, 100, 225, and 400 mm2 were woven, using two different carbon yarns with widths of 2 and 0.5 mm. The woven carbon nets were used before and after the core layer formation during mat forming of the particleboard. It was found that the insertion of carbon nets into the panel structure not only transforms insulated particleboard into a highly conductive composite but also significantly improves the flexural properties of the composite. However, the internal bond strength and physical properties of the composites were negatively affected by the presence of carbon nets in the panel structure, although their values were still above the minimum requirements of the standard values. Increasing the mesh area of the carbon nets and using thinner carbon yarns to weave the nets had a negative effect on the electrical and mechanical properties of the composites. In addition, a demonstration object was made of conductive composites to integrate lighting and a smartphone charging port into the object and prove the applicability of the developed composites for the furniture industry.Highlights Composites with carbon nets with smaller mesh area showed higher conductivity. The smaller the width of the carbon yarn, the higher the electrical resistance. The carbon net in the composites led to a decrease in internal bond strength. The carbon nets improved the flexural properties of the composites. Thickness swelling was significantly reduced by the use of carbon nets.

High-performance wearable flexible strain sensors based on an AgNWs/rGO/TPU electrospun nanofiber film for monitoring human activities

Abstract Wearable flexible strain sensors have attracted considerable attention in recent years, while it is still a significant challenge to fabricate wearable flexible strain sensors with high sensitivity and wide sensing range simultaneously. In this work, a high-performance wearable flexible strain sensor based on a thermoplastic polyurethane electrospun nanofibers (TPUNFs) film embedded with a silver nanowires/reduced graphene oxide (AgNWs/rGO) composite conductive material was fabricated via a simple drop-coating technique. The effect of the amount of AgNWs/rGO composite conductive material on the strain sensing range of the AgNWs/rGO/TPUNFs film flexible strain sensor was investigated, the strain sensing range of AgNWs/rGO/TPUNFs film flexible strain sensor was compared with that of the AgNWs/TPUNFs and GO/TPUNFs film flexible strain sensor, and the strain sensing properties of the AgNWs/rGO/TPUNFs film flexible strain sensor were measured. The results showed that the AgNWs/rGO/TPUNFs film flexible strain sensor with high sensitivity and wide sensing range simultaneously was achieved by compounding AgNWs and the reduced graphene oxide (rGO) conductive material. The strain sensing range of the AgNWs/rGO/TPUNFs film flexible strain sensor could be improved by increasing the amount of the AgNWs/rGO composite conductive material, and it was obviously better than that of AgNWs/TPUNFs and the rGO/TPUNFs film flexible strain sensor. The obtained AgNWs/rGO/TPUNFs film flexible strain sensor possessed high sensitivity (the gauge factor could reach a maximum of 2513.23.) as well as a wide sensing range (∼187%). Furthermore, the obtained AgNWs/rGO/TPUNFs film flexible strain sensor had a fast response/recovery time (200 ms/300 ms) and good cycling stability (∼3,000 cycles). Benefitting from the outstanding strain sensing performance, the AgNWs/rGO/TPUNFs film flexible strain sensor could detect large human motions such as finger, wrist, and knee bending as well as expression, which demonstrates great potential applications in wearable devices.

Synthesis and dynamic crosslinking of a hydroxyl-functionalized ethylene-propylene copolymer: Preparation of an elastomer with reprocessability and shape memory properties

The ternary copolymers of ethylene, propylene and 10-undecen-1-ol were prepared using a vanadium catalyst bearing an 8-anilide-5,6,7-trihydroquinoline ligand. By adjusting the concentration of 10-undecen-1-ol and polymerization temperature, the insertion rate of polar monomers was modulated with a maximum value of 3.8% achieved for 10-undecen-1-ol. With an increase in the hydroxyl insertion rate, the water contact angle of hydroxyfunctionalized ethylene-propylene copolymers decreased from 112.3° to 95.3°, indicating that the incorporation of 10-undecen-1-ol enhanced the hydrophilicity of the copolymers. Subsequently, a reprocessable ethylene-propylene rubber (EPR) with double dynamic bonds was synthesized through reaction between the hydroxyl group on functionalized ethylene-propylene copolymer and the crosslinking agent using isocyanate as chain end. The strength of functionalized ethylene-propylene copolymers was significantly improved through dynamic crosslinking. Significantly, the tensile strength of sample EP6-V-0.5 reached 14 MPa, which was 27 times higher than that of un-crosslinked EP6. The prepared functionalized ethylene-propylene rubber prepared exhibited not only reprocessability, but also remarkable shape memory and reshaping properties. Moreover, the conductive composite materials based on this rubber displayed great potential for application in motion sensors.

Spherical Shell with CNTs Network Structuring Fe-Based Alluaudite Na2+2 δ Fe2- δ (SO4 )3 Cathode and Novel Phase Transition Mechanism for Sodium-Ion Battery.

Iron-based sulfate cathodes of alluaudite Na2+2 δ Fe2- δ (SO4 )3 (NFS) in sodium-ion batteries with low cost, steady cycling performance, and high voltage are promising for grid-scale energy storage systems. However, the poor electronic conductivity and the limited understanding of the phase-evolution of precursors hinder obtaining high-rate capacity and the pure phase. Distinctive NFS@C@n%CNTs (n = 1, 2, 5, 10) sphere-shell conductive networks composite cathode materials are constructed creatively, which exhibit superior reversible capacity and rate performance. In detail, the designed NFS@C@2%CNTs cathode delivers an initial discharge capacity of 95.9 mAh g-1 at 0.05 C and up to 60 mAh g-1 at a high rate of 10 C. The full NFS@C@2%CNTs//HC cell delivers a practical operating voltage of 3.5V and mass-energy density of 140Wh kg-1 at 0.1 C, and it can also retain 67.37 mAh g-1 with a capacity retention rate of 96.4% after 200 cycles at 2 C. On the other hand, a novel combination reaction mechanism is first revealed for forming NFS from the mixtures of Na2 Fe(SO4 )2 ·nH2 O (n = 2, 4) and FeSO4 ·H2 O during the sintering process. The inspiring results would provide a novel perspective to synthesize high-performance alluaudite sulfate and analogs by aqueous methods.