Conductive Polymer Composites Research Articles

Densifying Conduction Networks of Vertically Aligned Carbon Fiber Arrays with Secondary Graphene Networks for Highly Thermally Conductive Polymer Composites

AbstractThermally conductive polymer composites hold great potential for thermal management applications in the electronics industry, but achieving metal‐like thermal conductivity (>200 W m−1 K−1) remains challenging due to the inevitable phonon scattering and the thermal resistance at filler‐filler and filler‐matrix interfaces. Herein, an efficient approach is presented to overcome this long‐standing barrier by designing a densified interconnecting filler framework, featuring a macro‐level carbon fiber (CF) array welded with a high‐quality, self‐assembled graphene network. In this framework, vertically aligned continuous CFs function as primary through‐plane thermal conduction paths, minimizing phonon scattering and thermal resistance. Meanwhile, the secondary graphene network interconnects the CFs into a more integrated and densified framework while introducing supplementary thermal conduction paths. Following polymer backfilling, the resulting epoxy nanocomposite exhibits an unprecedented through‐plane thermal conductivity of 262 W m−1 K−1 at a filler loading of 23.3 vol%, establishing a new benchmark among the thermally conducting polymer composites. When employed as a thermal interface material, this composite offers a 68.2% enhancement in cooling efficiency compared to standard commercial counterparts. Furthermore, the functional composite presents excellent Joule heating and interfacial adhesion properties, making it promising for thermal interface healing and multifunctional thermal management applications in complex environments.

Discussion on the thermal conductive network threshold of Al2O3/Co-continuous phase polymer composites

Achieving high thermal conductivity in polymer composites with micro or nanoparticle fillers are challenging. Typically, over 50 ​vol% filler loading is necessary to form a thermal conductive network. However, even with such a network in place, the increase in thermal conductivity may not be significant compared to that in electrically conductive composites. To clarify the ideal filler network structure, we endeavored to selectively disperse nano-sized Al₂O₃ nanoparticles at the interface of co-continuous SEBS/PA6 blends, with and without various filler surface modification methods. A thermal conductive network forms when all interface areas are fully covered by 2.56 ​vol% of Al2O3 nanoparticles (very close to theoretical loading content 2.29 ​vol%). In this case, the Al2O3 nanoparticle has the highest thermal conductive contribution (TCC). However, the absolute TCC values are extremely low because of the interfacial thermal resistance and it will decrease when the filler content exceeds 2.56 ​vol%, indicating that some nanoparticles are dispersed separately out of the existed thermal conductive network. These findings suggest that the construction of a connected thermal conductive network, relatively lower interfacial thermal resistance and the precise positioning of fillers within this network are essential for achieving high thermal conductivity composites.

A novel melt extrusion method for efficient and large-scale in-situ exfoliation of boron nitride to prepare high performance thermal conductive polymer composite

A novel melt extrusion method for efficient and large-scale in-situ exfoliation of boron nitride to prepare high performance thermal conductive polymer composite

Safe and Negligible-Loss Overcurrent Protection: A Novel Macromolecular Voltage Stabilizer for Conductive Polymer Composites

Safe and Negligible-Loss Overcurrent Protection: A Novel Macromolecular Voltage Stabilizer for Conductive Polymer Composites

Effect of Rheological on the Physical and Electrical Properties of Extruded Micro Carbon -LLDPE Composites

This study focuses on formulating and optimizing a conductive polymer composite (CPC) material tailored for electromechanical applications. Linear Low-Density Polyethylene (LLDPE) polymer and micro carbon particles derived from rice husk were compounded using a hot compaction process and melt blended through a single-screw extrusion machine. A mix of 50% loading of microcarbon particles was used in this research. It was determined that the experiment was successfully conducted, resulting in a stabilized density of approximately 1 g/cm³. The research demonstrates how the prototype Extruder Head effectively stabilizes the density of composites. Electrical conductivity demonstrated a notable increase in conductivity toward higher density. These findings underscore the successful development of a CPC material with improved electrical conductivity, making it a highly suitable tool for high carbon-loading composite material.

Investigating Conductive Polymer Composites Developed Using Acrylonitrile Butadiene Styrene/Graphene/Multi-walled Carbon Nanotubes for Effective Thermal Management

Investigating Conductive Polymer Composites Developed Using Acrylonitrile Butadiene Styrene/Graphene/Multi-walled Carbon Nanotubes for Effective Thermal Management

Development and Perspectives of Biobased Thermal Conductive Polymer Composites

Development and Perspectives of Biobased Thermal Conductive Polymer Composites

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.

Front Cover

The cover image is based on the Article Percolation behavior and sensing performance of polypropylene‐based conductive polymer composites under compressive strains and temperature by Zhi Wu et al., https://doi.org/10.1002/pol.20230894. Image Credit: Zhi Wu. Percolation behavior and sensing performance of polypropylene‐based conductive polymer composites filled with carbon black and multi‐walled carbon nanotubes (CB/PP, CB/MWCNTs/PP) are comparatively investigated. Under different compressive strains and temperatures, CB/MWCNTs/PP exhibits better conductivity and cyclic sensing properties owing to MWCNTs working as “bridges” between CBs. This is shown in the cover image by first author Zhi Wu. image

Boron nitride: The key material in polymer composites for electromobility

AbstractDespite the continuous development and improvement of many technologies and multifunctional materials for the electric powertrain (ePowertrain) for electric vehicles, there are still technical issues and challenges to address such as thermal management in batteries, electric motors, and power electronic devices, as most of their failures are due to poor thermal management. Consequently, conventional engineering polymer materials already used must be replaced since most of them have low thermal conductivity and are therefore limited in performance for thermal management applications. A key solution is to develop highly thermally conductive polymer composites that combine other features, such as flame‐retardant, electrical insulation, and mechanical and barrier properties, by incorporating fillers into the polymer matrix. This approach has attracted intensive research efforts. In this review, we first examine the key drivers, trends, and solutions of the ePowertrain segment, emphasizing thermal management. Second, special attention is given to the state‐of‐the‐art boron nitride (BN) polymer composites with current or potential applications in the automotive industry, especially, in batteries, electric motors, and power electronics. Third, analysis and prediction of thermal properties of BN polymer composites by finite element simulation are presented. Finally, outlooks for future research in this field are highlighted.Highlights Thermal management of batteries, electric motors and power electronics, using BN polymer composites, optimizes the functionality of electric vehicles. Cross‐linked polymers with BNNSs provide resins for high power motors, film capacitors, and Li‐metal battery electrolytes for electric vehicles. Mathematical modeling and life cycle analysis can predict trends and research gaps in ePowertrain applications.

Usage of coil-shaped conductive polymer composite as intrinsically flexible flaw sensing probe

The assessment of buried flaws in the interlayer structure of curved metal is crucial to system safety. To improve the flexibility of eddy current sensor, an intrinsically flexible flaw sensing probe made of coil-shaped conductive polymer composite is proposed. The experimental data show that the response signal of the coil-shaped composite changes at the flaw and increases with the increases of flaw height/length, with a maximum sensitivity of 0.435 mV/mm for differential amplitude and 4.904 °/mm for differential phase. The results show that the height of the characteristic signals in the response signals reflects the change in flaw height, and the length of the characteristic signals in the response signals reflects the change in flaw length. The relative change rate of the coil-shaped composite is higher than that of a metal coil of the same structure. The above results have laid a preliminary foundation for using the coil-shaped composite to detect flaws.

Significant enhancement of bi-directional ultrahigh thermal conductivity in polymer composites fabricated via Polyetherimide@Silver core–shell structured microspheres

Nowadays, the polymer-based composites with excellent thermal-conductive ability and ideal electromagnetic interference shielding performance are in great demand with the advent of developing modern electronic technology. However, most conventional thermal-conductive materials were typically designed to enhance thermal conductivity in just one single direction (through-plane or in-plane direction), which will be inadequate to meet increasing heat-dissipation requirements. Hence, polyetherimide/Silver (PEI/Ag) composites with unique segregated thermal-conductive network were fabricated via hot-pressing the core–shell (PEI@Ag) particles, which was endowed with superior thermal-conductive ability in bi-directions. By this process, the Ag shell was deposited on the surface of various polymer microsphere, and diverse morphology of composite particles would lead to different findings. The results show the PEI@Ag composites with filler content of 18.9 vol% exhibited high in-plane thermal conductivity and through-plane thermal conductivity of 19.9 and 14.0 W/mK, respectively. Particularly, these results achieved obvious improvements of 331 % and 1264 % higher than the composites with filler random distribution, indicating the composite materials obtained outstanding advantage in both horizontal and vertical direction. The research also found that the composites prepared from PEI@Ag core–shell structures possess better properties than those prepared with Ag nanoparticles growing on polymers, indicating the importance of continuous heat-transfer path, and their heat transfer behavior was further demonstrated by finite element analysis. Besides, the composites also exhibited remarkable EMI shielding performance (40.1 dB)). In a word, this study provides viable strategies to enhance the thermal conductivity of composites based on organic solvent-soluble polymer with EMI capability for the development of electronic devices.

Thermal conductivity enhancement of epoxy by a 3D Si3N4 crystal rod/grain skeleton fabricating from photovoltaic silicon waste

Silicon nitride (Si3N4) is one of the preferred fillers for the preparation of high thermal conductivity polymer composites because of its intrinsic high thermal conductivity and good electrical insulation. To maximize the thermal conductivity enhancement effect of the fillers in the composites, it is necessary to pre-construct a three-dimensional (3D) thermally conductive filler network. Herein, surfactant foaming was applied to pre-construct a 3D Si-containing framework from photovoltaic silicon waste (PSW), which was subsequently transformed into a porous skeleton consisting of Si3N4 rods and grains by in-situ nitridation reaction sintering. And finally, thermal conductive Si3N4/epoxy (EP) composites were fabricated after infiltrating EP into the network skeleton. When the filler content of Si3N4 was 41.00 vol%, the obtained Si3N4/EP composite showed the highest thermal conductivity of 2.99 W·m-1·K-1, which was 13.95 times higher than that of pure EP. Tests on running CPU and heating table showed that the Si3N4/EP substrate had excellent heat dissipation performance compared to the pure EP substrate. The 3D continuous network formed by "bridging" between two different morphologies of Si3N4 microcrystals contributed to providing effective multi-directional heat transfer paths and thereby improving the thermal conductivity of the composites. Overall, the low cost of raw silicon source originating from industrial waste as well as the simple and practical construction of heat-conducting filler network demonstrate the promising application of the Si3N4/EP composites fabricated in our work.

Highly Interconnected Thermal Conduction Highway for Highly Thermally Conductive and Mechanically Strong Polymeric Composites.

Industrial implementation of highly thermally conductive polymeric composites has been hindered by several hurdles, such as the low intrinsic thermal conductivity (TC) of polymers, the use of expensive thermally conductive fillers, and difficulty in processing composites with high filler loading. In this study, we introduce a straightforward fabrication method for a high TC polymeric composite with a programmed internal structure of a highly interconnected thermal conduction highway (HITCH) by the simple addition of partially cured resin fragments into the conventional filler/resin combination. Critical variables, such as the concentration of the added resin fragments and the local concentration of hexagonal boron nitride (hBN) in the HITCH, as well as the packing density of the fragments, were systematically tuned to maximize the TC with the use of the least amount of the filler. Careful choice of the compositions enabled a significant TC enhancement of the composite by 2.6 times (6.5 W/mK) compared to the value of the conventional composite at the same overall concentration of hBN (∼2.5 W/mK). Finally, a composite with high TC (∼12 W/mK) and strong tensile strength (∼22.6 MPa), which is good enough for most practical thermal management applications, could be successfully fabricated with the use of the least amount of the filler (∼34 wt %). The comprehensive study of the HITCH composite here can be easily extended to other combinations with various fillers and matrices and may provide a library to researchers looking for advanced materials for future thermal management systems.

Carbon fiber/boron nitride fillers for enhancing through-plane thermal conductivity of poly(vinylidene fluoride): Synergistic effect and mechanism

Two series of thermally conductive poly(vinylidene fluoride) (PVDF) composites were prepared by adding boron nitride (BN) and carbon fiber (CF) of different mass ratios via hot-pressing. The synergistic effects of the dual fillers on the thermal conductivity enhancement were investigated. The morphology, thermal conductivity, crystallinity, thermal stability, mechanical properties, and long-term chemical stability of the PVDF composites were characterized. The results demonstrated a significant synergistic effect between the BN and the CF on enhancing the thermal conductivity of the PVDF-based composites. The maximum thermal conductivity of 1.89 W/(m·K) with an improvement of 1014 % was achieved when 15 wt% BN and 15 wt% CF were added in the PVDF matrix. The synergistic effect resulted in the formation of efficient three-dimensional thermally conductive networks with a synergistic efficiency up to 113 %. The Agari model was employed to illustrate the thermal conduction mechanism, revealing the improved ability of the dual fillers to form conductive pathways. The PVDF composites showed good crystallinity, thermal stability, mechanical strength, and long-term chemical stability. This study highlights the potential of the PVDF/BN/CF composites for applications in membrane heat exchangers and provides significant insights into the design of high-performance thermally conductive polymer composites.

Customizable gradient MXene/polyurethane modules for electromagnetic interference shielding with low reflection and thermal management

The conductive polymer composites (CPC) with elevated levels of conductivity typically exhibit enhanced electromagnetic interference shielding effectiveness (EMI SE), however, this enhancement is often paralleled by an augmented risk of secondary electromagnetic (EM) pollution, attributable to the increased EM reflection. Developing a facile method to construct an eco-friendly CPC for EMI shielding that simultaneously exhibits low reflection and high shielding performance remains a promising yet challenging pursuit. Moreover, excellent shielding materials should possess exceptional thermal management capabilities to protect individuals or equipment under extreme conditions. Herein, we have engineered the MXene/polyurethane (MXene/PU) sponge (MPS) modules characterized by the hierarchical porous structure. Through the strategic modular combination of impedance-matching and impedance-mismatching modules tailored for different application contexts, the customizable gradient MXene/PU sponge (GMPS) facilitates achieving a balance of exceptional average EMI SE (44.6 dB), a low reflection coefficient (R = 0.18), and superior photo/electrothermal conversion capability. Furthermore, both experimental results and finite element analyses are adopted to explore the effect of the arrangement order of GMPS on EMI shielding performance. Leveraging the green, health-conscious, and flexibly customizable approach, it manifests tremendous potential across various areas, including intelligent residences and multifunctional integrated systems.

Regulation of Mechanical Properties of Conductive Polymer Composites

Regulation of Mechanical Properties of Conductive Polymer Composites

Comprehensive Study of Mechanical, Electrical and Biological Properties of Conductive Polymer Composites for Medical Applications through Additive Manufacturing.

Conductive polymer composites are commonly present in flexible electrodes for neural interfaces, implantable sensors, and aerospace applications. Fused filament fabrication (FFF) is a widely used additive manufacturing technology, where conductive filaments frequently contain carbon-based fillers. In this study, the static and dynamic mechanical properties and the electrical properties (resistance, signal transmission, resistance measurements during cyclic tensile, bending and temperature tests) were investigated for polylactic acid (PLA)-based, acrylonitrile butadiene styrene (ABS)-based, thermoplastic polyurethane (TPU)-based, and polyamide (PA)-based conductive filaments with carbon-based additives. Scanning electron microscopy (SEM) was implemented to evaluate the results. Cytotoxicity measurements were performed. The conductive ABS specimens have a high gauge factor between 0.2% and 1.0% strain. All tested materials, except the PA-based conductive composite, are suitable for low-voltage applications such as 3D-printed EEG and EMG sensors. ABS-based and TPU-based conductive composites are promising raw materials suitable for temperature measuring and medical applications.

Hydrogen-peroxide intercalated expanded graphite facilitates large enhancement in thermal conductivity of polyetherimide/graphite nanocomposites

In this work, we prepared expanded graphite (EG) filler using hydrogen peroxide (H2O2) as an oxidizing agent to study its impact on the thermal conductivity (k) of polyetherimide (PEI) composite, compared to EG prepared using sodium chlorate (NaClO3). Sulfuric acid was used as the primary intercalating agent for both synthesis routes. The use of H2O2 prepared EG (EG-H2O2) led to a remarkable ∼4030% enhancement (9.5 Wm−1K−1) in k of the PEI/EG composite, while the use of NaClO3 prepared EG (EG-NaClO3) led to a much smaller enhancement of ∼2190% (5.3 Wm−1K−1), at 10 wt% EG composition compared to kPEI (∼0.23 Wm−1K−1). Such findings exceed the current state-of-art in EG-based polymer composites. Detailed characterization was performed to understand the properties of EG-H2O2 and EG-NaClO3. Raman analysis revealed that H2O2 resulted in relatively defect-free EG (ID/IG ratio ∼0.04), thus preserving the k of graphite (∼2000 Wm−1K−1). Use of NaClO3, however, led to a large defect density (ID/IG ratio ∼0.25), yielding graphite with significantly diminished k. Furthermore, through-plane thermal diffusivity of EG-H2O2 paper was measured to be 9.5 mm2s-1 while that of NaClO3 case was measured to be 6.7 mm2s-1, thus directly confirming the beneficial impact of H2O2 in preserving the high k of graphene. X-ray photoelectron spectroscopy (XPS) revealed that the higher number of defects in EG-NaClO3 are due to the higher degree of oxidation induced by NaClO3. The results demonstrate the potential of EG-H₂O₂ as an efficient filler for achieving high thermal conductivity polymer composites.

PLA/CB and HDPE/CB conductive polymer composites: Effect of polymer matrix structure on the rheological and electrical percolation threshold

AbstractIn this study, the effect of the polymer matrix structure on the rheological and electrical percolation threshold of polymer/carbon black (CB) conductive polymer composites (CPCs) was investigated. Poly(lactic acid) (PLA) and high‐density polyethylene (HDPE) were used as polymer matrices. Through rheological analyses, an increase in complex viscosity was observed with increasing CB concentration, accompanied by a reduction in the Newtonian plateau. Additionally, an increase in the solid‐like behavior was observed, suggesting the formation of a percolated network. The rheological percolation threshold was found to be 5.13% CB mass fraction for the PLA/CB composite and 10.72% for the HDPE/CB composite. Electrical conductivity results were fitted to the sigmoidal Boltzmann model, and its derivative was used to identify the electrical percolation threshold. For PLA/CB, this threshold was reached at 5.39% CB mass fraction, while for HDPE/CB, it occurred at 5.75%. Morphology analysis by scanning electron microscopy and atomic force microscopy indicated that the polymer matrix structure affected the distribution/dispersion of the CB particles within the polymer matrix.Highlights The effect of polymer matrix structure on polymer/CB CPCs was investigated. The crystallinity of the polymer matrix affected the percolation threshold. PLA/CB showed higher conductivity than HDPE/CB CPCs.