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Expanded graphite (EG) based phase change material (PCM) has attracted significant concern in thermal management systems. In this paper, a series of composite PCMs composing of EG with different sizes (50, 80, and 100 mesh) as the substrate, and palmitic acid (PA) as the PCM, were prepared by vacuum impregnation method. The results shown that the size of EG particles effect the adsorption capacity of PA. The mass fraction of PA in PA/EG-50 reached 83.6% and the enthalpy of melting and solidification of PA/EG-50 are 160.13 J/g and 159.75 J/g, respectively. The thermal conductivity decreased slightly as the particle size of EG increased, and the thermal conductivity of PA/EG-100 is the highest of 4.86 W/(m·K). The TGA results show that all composite PCMs present good thermal stability below 200 °C. The electro-thermal conversion efficiency increased with the particle size of EG increasing, and the electro-thermal conversion efficiency of PA/EG-100 reached up to 91.39% under low-voltage conditions (1.9 V). These results throw light on the potential application of EG-based composite PCM, especially for the electro-thermal conversion. [ABSTRACT FROM AUTHOR]

This paper introduces an innovative design for an "inorganic salt-expanded graphite" composite thermochemical system. The storage unit is made of a perforated, compressed, expanded graphite block impregnated with molten CaCl2∙6H2O; the humid air passes through the holes that allow the moisture to diffuse and react with the salt. The prepared block underwent 90 hydration-dehydration cycles. Although most of the performed cycles were carried out with salt overhydration and deliquescence, the treated samples have remained mechanically and thermally stable with no drop in energy density. The volumetric energy density of the composite ranged from 135.5 to 277.6 kWh/m3, depending on airflow rate and absolute humidity. To ensure composite material cycling stability, the energy density of the block was measured during hydration at similar conditions of absolute humidity, inlet temperature, and airflow rate (0.01 kgwater/kgair, 20 °C, 400 l/min). The average energy density at these conditions was sustained at 219 kWh/m3. The block integrity was monitored by visual inspection after removing it from the reactor chamber every few cycles. Both the composite material and its manufacturing process are simple and easy to scale up for future commercialization. [ABSTRACT FROM AUTHOR]

• Composite PCM with sub-zero phase change temperature was developed. • Eutectic dodecane-hexadecane (DD-HD) with optimal mass ratio of 80:20 was obtained. • Composite of DD-HD and expanded graphite (EG) was optimized with 10 wt% EG. • DD-HD/EG shows high latent heat, thermal conductivity and thermal reliability. Utilization of phase change materials (PCMs) for cold energy storage has garnered increasing attention. This study focuses on the development of a composite PCM by integrating a novel eutectic dodecane-hexadecane (DD-HD) PCM into expanded graphite (EG), to cater to the demands of sub-zero cold energy storage applications, such as cold chain logistics. The study identified the optimal mass ratio of DD-HD as 80:20. A series of DD-HD/EG composites were fabricated through a combination of high-speed emulsification and physical adsorption methods. The adsorption capacity of EG for the eutectic PCM mixture was evaluated by examining the impact of EG fraction on the leakage of the composite PCM, revealing that the optimum EG fraction is 10 wt%. The composite PCM displayed a sub-zero phase change temperature of -12.09 ℃, a high melting enthalpy of 178.75 kJ/kg, and a high thermal conductivity of 5.18 W/(m•K). The thermal conductivity of the composite was enhanced by 22.52 times compared to the base PCM. Thermogravimetric analysis indicated that the decomposition temperature of DD-HD/EG was significantly higher than that of the base PCM. The composite demonstrated outstanding thermal reliability, as evidenced by thermal cycle tests. With its impressive thermal characteristics, this composite shows great potential for various cold energy storage applications. [ABSTRACT FROM AUTHOR]

In this work, different kinds of silane coupling agents modified expanded graphite (MEG) fillers were successfully prepared and then incorporated into silicon rubber matrix to fabricate flame‐retardant composite materials (SR/MEG). The inserted MEG fillers with siloxane chains exhibited good compatibility with the silicon rubber matrix, which cannot only reduce the negative impact of adding fillers on mechanical properties but also endow the silicon rubber composites with ideal flame retardancy. Subsequently, platinum (Pt) catalyst was incorporated into the SR/MEG composites to prepare SR/MEG/Pt composites, and the synergistic effects of MEG and Pt catalyst on the thermal stability, flame retardancy, and combustion behavior of silicon rubber composites were systematically investigated. The target SR/MEG/Pt composite with appropriate addition of MEG and Pt catalyst can obtain relatively high char residue of 41.9% and limiting oxygen index value of 29.6%, as well as achieve V‐0 rating in the vertical combustion test, owing to the formation of expanded and dense silicon–carbon protective layer under the catalysis of Pt catalyst. Moreover, the cone calorimeter test results showed that the peak of heat release rate and total heat release of SR/MEG composites were further reduced after the addition of an appropriate amount of Pt catalyst, manifesting the good synergistic effect of MEG and Pt catalyst on the flame retardancy performance of silicon rubber. The method proposed herein may provide a promising way for fabricating high‐performance flame‐retardant silicone rubber materials. [ABSTRACT FROM AUTHOR]

Dismantling behavior of aluminum/carbon fiber-reinforced plastic (aluminum/CFRP) bonded assemblies using dismantlable adhesives was investigated. These adhesives contained expanded graphite (EG) to facilitate the dismantling process by inducing volume expansion during heating. Our objective was to identify the optimal additive conditions of EG, which would allow for easy dismantling while maintaining adequate adhesive strength in aluminum/CFRP bonded assemblies during regular operation. To achieve this, various experiments with adhesives containing EG of different flake sizes and volume fractions were conducted. The experimental results demonstrated that a moderate addition of fine-flake sized (140 μm) EG (5 vol%) tended to provide the desired combination of sufficient adhesive strength and ease of dismantling. [ABSTRACT FROM AUTHOR]

Developing materials for efficient energy storage and effective electromagnetic interference (EMI) shielding is crucial in modern technology. This study explores the synthesis and characterization of carbonaceous shape-stabilized octadecane/MWCNT (multi-walled carbon nanotube) composites, utilizing activated carbon, expanded graphite or ceramic carbon foam, as shape stabilizers for phase change materials (PCMs) to enhance thermal energy storage and EMI shielding, for energy-efficient and advanced applications. The integration of octadecane, a phase change material (PCM) with carbonaceous stabilizers ensures the material's stability during phase transitions, while MWCNTs contribute to improved thermal storage properties and EMI shielding capabilities. The research aims to develop novel composites with dual functionality for thermal storage and EMI shielding, emphasizing the role of carbon matrices and their MWCNT composites. SEM and CT microtomography analyses reveal variations in MWCNT incorporation across the matrices, influenced by surface properties and porosity. Leaching tests, infrared spectroscopy (FT-IR) and differential scanning calorimetry (DSC) confirm the composite's stability and high latent heat storage. The presence of nanotubes enhances the thermal properties of octadecane and ΔH values almost reached their theoretical values. EMI shielding effectiveness measurements indicate that the composites show improved electric properties in the presence of MWCNTs. [ABSTRACT FROM AUTHOR]

Highlights Expanded graphite (EG) is a desired filler for electrothermal and electromagnetic interference (EMI) shielding because of its easy access, low‐cost, lightweight, high conductivity, and heat sensitivity. Herein, fluffy EG was prepared from natural flake graphite (NFG) by a simple expansive technology and subsequently heat treatment at 800°C for 2.0 h in 5% Ar/H2 atmosphere. EG/silicone films with a filling ratio of 15 wt% were obtained via hot‐pressing, which exhibited sensitive electrothermal and excellent EMI shielding performances. When the applied voltages were 5.0, 10.0, and 15.0 V, the steady‐state temperatures were 54.0, 136.5, and 237.8°C in the 30s, respectively. Meanwhile, their average EMI shielding efficiency was greater than 20 dB in 2–18 GHz at 0.84 mm, which was 6.3 times as much as NFG/silicone film. Therefore, this study offers a simple and effective strategy for preparing excellent electrothermal‐EMI shielding materials. Fluffy EG is prepared by a simple expansive method and treatment at 800°C. EG/silicone films exhibit good electrothermal and EMI shielding performances. Steady temperatures of 55.0/136.5/237.8°C are gotten at 5/10/15 V in 30 s. The EMI shielding efficiency is greater than 20 dB at 0.84 mm. Good properties are due to the EG with high conductivity and fluffy structure. [ABSTRACT FROM AUTHOR]

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Fe(NO3)3, Co(NO3)2, and Ni(NO3)2 catalysts were used to form carbon nanotubes in situ from expanded graphite by changing the type, concentration and carbonization temperature of the catalysts. The microstructure, modified expanded graphite functional group and oxidation temperature of the formed carbon nanotubes were detected and analyzed. The effects of catalyst concentration and type, the ratio of carbon source Carbons P to expanded graphite and heat treatment temperature on the in-situ catalytic formation of carbon nanotubes by expanded graphite were studied and characterized by X-ray diffraction (XRD), X-ray photoelectron spectrometer (XPS), Raman spectrometer (Raman), scanning electron microscope (SEM), and thermogravimetric analysis-differential scanning calorimetry (TG-DSC) in this paper. The formation mechanism and influence rule of different experimental conditions on carbon nanotubes are studied. [ABSTRACT FROM AUTHOR]

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.

Abstract The expanded graphite (EG) was used as a filler in EG/polyurethane (PU) composite foams for electromagnetic interference shielding (EMI). The EG/PU composite foams were characterized by Fourier transform infrared spectroscopy (FTIR) and SEM. The shielding effectiveness (SE) of the EG/PU composite form containing 5 wt% EG was −24 dB at 5 wt% in the 8–12 GHz range. The optimal EG loading was 3 wt% and the corresponding EG/PU composite foam had a total SE of −18.9 dB and fairly good mechanical characteristics (compressive strength: 13.43 MPa and compressive modulus: 4.95 MPa). These attributes position the EG/PU composite foam as a promising candidate for diverse EMI SE applications. Highlights Synthesis by thermal exfoliation and characterization by x‐ray diffraction, Raman and SEM of EG. Preparation of EG/PU foams for enhanced EMI SE. Optimization of the EG loading with regard to SE and mechanical properties of the EG/PU foams.

Abstract Expanded graphite has promising potential environmental applications due to its porous structure and oleophilic nature, which allow it to absorb large quantities of oil. The material is produced by intercalating graphite and applying heat to convert the intercalant into gas to cause expansion between the layers in the graphite. Using different intercalants and temperature conditions results in varying properties of expanded graphite. This work has proven that the sorption properties of commercial expanded graphite differ significantly due to the material’s structural and elemental characteristics, which can be attributed to the intercalation method. This resulted in various degrees of exfoliation of the graphite and possible functionalisation of the graphene sheets within the structure. This affected the material's sorption capacity and its affinity for heavy metal sorption by incorporating selectivity towards the sorption of certain metals. It was found that sample EG3, which underwent a less harsh expansion, exhibited lower porosity than EG1, and thus, the sample absorbed less oil at 37.29 g/g compared to the more expanded samples EG1 and EG2 with 55.16 g/g and 48.82 g/g, respectively. However, it was able to entrap a wider variety of metal particles compared to EG1 and EG2, possibly due to its smaller cavities allowing for a capillary effect between the graphene sheets and greater Van der Waals forces. A second possibility is that ionic or coordination complexes could form with certain metals due to the possible functionalisation of the expanded graphite during the intercalation process. This would be in addition to coordination between the metals and expanded graphite carbon atoms. The findings suggest that there is evidence of functionalisation as determined by XRD and elemental analyses. However, further investigation is necessary to confirm this hypothesis. The findings in this work suggest that the first mechanism of sorption was more likely to be related to the degree of expansion of the expanded graphite. Various metals are present in used oil, and their removal can be challenging. Some metals in oil are not considered heavy since they have a relatively low density but can be associated with heavy metals in terms of toxicity.

Poly(vinylidene fluoride) (PVDF) based conducting polymer composites with carbon nanomaterials can be used for mechanical energy harvesting through piezoelectric or triboelectric effect. This study aims to investigate the influence of PMMA molecular weight on the electrical, thermal, and wetting properties of PVDF/40 wt.% PMMA blend nanocomposites reinforced with expanded graphite (ExGr). The blend nanocomposites with 40 wt.% PMMA have been prepared by solution blending method by using two different molecular weights of PMMA whose melt flow indices are 2 g/10 min and 2.3 g/10 min. The coexistence of the electroactive gamma and non-polar alpha phases of PVDF in the blend nanocomposites has been confirmed by X-ray diffraction, Fourier transform infrared spectroscopy and differential scanning calorimetry analyses. While overall crystallinity (%) of low molecular weight PMMA employed blend nanocomposites is lower than that of high molecular weight PMMA blended nanocomposites, the electroactive gamma phase has been found to increase in the former blend nanocomposites. The dispersion of graphite nanosheets has been observed to be better in high molecular weight PMMA employed blend nanocomposites which results in higher electrical conductivity. Impedance analysis of PVDF-40 wt.% PMMA-2 wt.% ExGr blend nanocomposite with high molecular weight PMMA results in enhanced interjunction capacitance (74.5 pF) in comparison to low molecular weight PMMA mixed blend nanocomposites (68 pF). Water contact angle (WCA) increases with molecular weight of PMMA and ExGr loading level. Thermogravimetric analysis has shown that the char content (above 500°C) is slightly higher for the blend with low molecular weight PMMA than with high molecular weight PMMA. [ABSTRACT FROM AUTHOR]

This study investigated the effects of intercalation and exfoliation of the graphite flake particles on the mechanical properties of elastomeric composites using analytical, computational, and experimental techniques. Relying on the modified Eshelby and incremental Mori–Tanaka approach, a new micromechanics model was proposed to estimate Young's modulus and develop a constitutive model for expanded graphite (EG)-filled elastomer in finite strain deformation. It was found that when the initial graphite flakes expanded, the actual volume fraction and ultimate aspect ratio of the dispersed particles significantly affected the mechanical properties of the EG-reinforced composites. The present model and subsequent predictions reflect the initial flake diameter, actual volume fraction, ultimate aspect ratio of the particles, and other convenient physical properties of the composite constituents. In addition, molecular dynamics simulations were performed to evaluate the elastic properties of the EG-Matrix interphase region using the COMPASS force field function. The MD results showed that Young's modulus of the interphase region increased significantly as the quantity of the graphene layer increased. The micromechanics-constitutive model results were validated using the experimentally determined stress–strain relation of the composites. EG- and CB-elastomer nanocomposite specimens were fabricated and tested in the experimental program. Field emission scanning electron microscopy (FESEM) analysis of the cryo-fractured surfaces of the elastomer compounds showed good interactions between the constituents. Numerical computations indicated that the proposed model incorporating the new parameters could accurately predict the experiment at a small particle concentration. [ABSTRACT FROM AUTHOR]

The efficiency and economy of an ASHP (air source heat pump) can be significantly improved in a cold area by combining it with a TESU (thermal energy storage unit). The work of looking for a phase change material with a suitable temperature range, a large thermal capacity, and high conductivity has been always on the road. This paper prepared 10 CPCMs (composites of a phase change material) by using the vacuum adsorption method, which consists of LA (lauric acid) as the phase change material and EG (expanded graphite) as the skeleton matrix for its high thermal conductivity and porous characteristics. By characterizing and analyzing their basic properties, surface morp\hology, and stability, a suitable CPCM for the TESU coupled with the ASHP heating system is found. The leakage experiment results show that the maximum effective content of LA absorbed in 100-mesh EG of a CPCM is 80%, and that in 200-mesh EG, it is 90%. Among 10 CPCMs, CPCM3, with a mass ratio of LA:EG/8:2, is considered the more satisfactory one for the TESU proposed by this paper, because its performance shows good stability, its phase transition temperature is 40.98–41.94 °C, its latent heat is 164.34–168.28 kJ/kg, and especially, its thermal conductivity is 8.15–8.33 W/(m·K). This paper will be followed by performance research on TESUs coupled with ASHP heating systems. [ABSTRACT FROM AUTHOR]

Diverse expansion volumes of expanded graphite (EG) were synthesized utilizing the chemical oxidation technique, and modified EG was produced by coating EG with distinct expansion ratios employing polyacrylate. The modified EG/natural rubber (NR) composites were fabricated using the modified EG, and the impacts of varying expansion volumes of EG on the mechanical and thermal characteristics of these composites were scrutinized. The findings revealed that following polyacrylate modification, the surface roughness and active groups of EG experienced a substantial increase. The tensile strength of the composite material escalated in correlation with the expansion volume of the modified EG, exhibiting an enhancement of 81.72%. The elongation at break, stress at a specified elongation, and thermal conductivity demonstrated a pattern of initially increasing and subsequently decreasing as the expansion volume increased. The thermal conductivity of the material reached its peak at an EG expansion volume of 20 g/mL, with a thermal conductivity of 0.569, and an overall favorable mechanical performance. [ABSTRACT FROM AUTHOR]

The purpose of the work is to establish the possibility of obtaining expanded graphite of high purity (carbon content more than 99.5 % wt.) from flotation-enriched graphite (carbon content 94–97 % wt.) by combining into one process intercalation of graphite with a solution of potassium dichromate in concentrated sulfuric acid with subsequent hydrolysis, and chemical purification using solutions of ammonium bifluoride in sulfuric or hydrochloric acid and Trilon B in an alkaline buffer as purification reagents, and to confirm this possibility by quantum chemical calculations. It has been experimentally shown that combining oxidized graphite synthesis and its chemical purification into one process allows obtaining expanded graphite of high purity, with a carbon content of 99.75–99.85 % wt. The methods of X-ray diffraction and thermogravimetry show that the interaction of oxidized graphite (the residual compound of intercalation of graphite with sulfuric acid) with cleaning reagents does not reduce the ability to expand. The magnitude of the mass loss of oxidized graphite according to various variants of chemical post-cleaning and the temperature range of such loss remain practically unchanged. Quantum chemical calculations of the adsorption energy (∆Eads) of one molecule of Trilon B on the surface of a graphene-like plane (GLP), the complexation reaction of metal sulfates, the energy effect of the interaction of Trilon B with sulfates of alkaline earth metals in an aqueous solution, and with the participation of the surface of the graphene plane were carried out using the GAMESS (US) program by the density functional theory (DFT) method with the B3LYP functional and the 6-31G(d,p) basis set, taking into account the Grimme D3 dispersion correction within the PCM polarizable continuum. The results of the analysis of quantum chemical calculations indicate that the Trilon B molecule is better physically sorbed on the oxidized GLP (–412 kJ/mol) than on its native form (–188 kJ/mol). The values of the energy effect of the complexation of magnesium and calcium cations with Trilon B have a negative value both in an aqueous solution and in the presence of the oxidized form of GLP. This indicates the thermodynamic probability of this process, which is consistent with the experimental results. Regardless of the nature of the cation, its interaction with Trilon B is thermodynamically more likely in an aqueous solution than in the adsorbed state on the surface of oxidized GLP. [ABSTRACT FROM AUTHOR]

The mass content of expanded graphite (EG) in fatty acid/expanded graphite composite phase-change materials (CPCMs) affects their thermal properties. In this study, a series of capric– myristic acid/expanded graphite CPCMs with different EG mass content (1%, 3%, 5%, 8%, 12%, 16%, and 20%) were prepared. The adsorption performance effect of EG on the PCMs was observed and analyzed. The structure and thermal properties of the prepared CPCMs were characterized via scanning electron microscopy, differential scanning calorimetry, thermal conductivity measurements, and heat energy storage/release experiments. The results show that the minimum mass content of EG in the CPCMs is 7.6%. The phase-change temperature of the CPCMs is close to that of the PCMs, at around 19 ◦C. The latent heat of phase change is equivalent to that of the PCM at the corresponding mass content, and that of phase change with an EG mass content of 8% is 138.0 J/g. The CPCMs exhibit a large increase in thermal conductivity and a significant decrease in storage/release time as the expanded graphite mass content increases. The thermal conductivity of the CPCM with a mass content of 20% is 418.5% higher than that with a mass content of 5%. With an increase in the EG mass content in CPCMs, the heat transfer mainly transitions from phase-change heat transfer to thermal conductivity. [ABSTRACT FROM AUTHOR]

Phase change materials (PCMs) are a kind of highly efficient thermal storage materials which have a bright application prospect in many fields such as energy conservation in buildings, waste heat recovery, battery thermal management and so on. Especially inorganic hydrated salt PCMs have received increasing attention from researchers due to their advantages of being inexpensive and non-flammable. However, inorganic hydrated salt PCMs are still limited by the aspects of inappropriate phase change temperature, liquid phase leakage, large supercooling and severe phase separation in the application process. In this work, sodium acetate trihydrate was selected as the basic inorganic PCM, and a novel shape-stabilized composite phase change material (CPCM) with good thermal properties was prepared by adding various functional additives. At first, the sodium acetate trihydrate-acetamide binary mixture was prepared and the melting point was adjusted using acetamide. Then the binary mixture was incorporated into expanded graphite to synthesize a novel shape-stabilized CPCM. The thermophysical properties of the resultant shape-stabilized CPCM were systematically investigated. The microscopic morphology and chemical structure of the obtained shape-stabilized CPCM were characterized and analyzed. The experiment results pointed out that acetamide could effectively lower the melting point of sodium acetate trihydrate. The obtained shape-stabilized CPCM modified with additional 18% (mass fraction) acetamide and 12% (mass fraction) expanded graphite exhibited good shape stability and thermophysical characteristics: a low supercooling degree of 1.75°C and an appropriate melting temperature of 40.77°C were obtained; the latent heat of 151.64 kJ/kg and thermal conductivity of 1.411 W/(m·K) were also satisfactory. Moreover, after 50 accelerated melting-freezing cycles, the obtained shape-stabilized CPCM represented good thermal reliability. [ABSTRACT FROM AUTHOR]

The expanded graphite (EG) was used as a filler in EG/polyurethane (PU) composite foams for electromagnetic interference shielding (EMI). The EG/PU composite foams were characterized by Fourier transform infrared spectroscopy (FTIR) and SEM. The shielding effectiveness (SE) of the EG/PU composite form containing 5 wt% EG was −24 dB at 5 wt% in the 8–12 GHz range. The optimal EG loading was 3 wt% and the corresponding EG/PU composite foam had a total SE of −18.9 dB and fairly good mechanical characteristics (compressive strength: 13.43 MPa and compressive modulus: 4.95 MPa). These attributes position the EG/PU composite foam as a promising candidate for diverse EMI SE applications. Highlights: Synthesis by thermal exfoliation and characterization by x‐ray diffraction, Raman and SEM of EG.Preparation of EG/PU foams for enhanced EMI SE.Optimization of the EG loading with regard to SE and mechanical properties of the EG/PU foams. [ABSTRACT FROM AUTHOR]

A mechanically homogenized composite of expanded graphite and cobalt(II) perrhenate has been described. Cobalt(II) perrhenate was obtained in a reaction of perrhenic acid with cobalt(II) nitrate. A simple mortar homogenization method was used to enhance the intercalation of cobalt species within the carbon matrix. The specific capacitance of the composite was enhanced by 50% (to 78 F/g) in comparison to bare expanded graphite (52 F/g). The electrochemical characteristics were significantly improved, including better cyclability (7% capacitance loss), a lower resistance of the electrode material, and a lower iR drop, with respect to expanded graphite without cobalt(II) perrhenate active species. Expanded graphite, with its unique specific surface area and pore size diameter, was proved to be a potential and cheap carbon support. [ABSTRACT FROM AUTHOR]

Polymer composites offer numerous benefits, including low cost, easy processability, and diverse applications. In this work, we fabricated a composite material with high thermal conductivity and electromagnetic interference (EMI) shielding performance using EGaIn, a liquid metal (referred to as LM in this paper), MXene (MX), and expanded graphite (EG) as multifunctional fillers, along with polyacrylic acid (PAA). LM was used to exfoliate MX under the effect of shear force, which not only reduced the size of MX but also increased the aspect ratio of the 2D‐structured MX. MX was filled into the pores of EG to make a heat transfer path, thereby enhancing its thermal conductivity, mechanical properties, and EMI SE properties. LM served as the initiator of free‐radical polymerization to convert acrylic acid (AA) into PAA. Finally, the LMMX/EG/PAA composite was hot‐pressed to make the heat‐transfer path dense. As a result, the LMMX/EG/PAA composite exhibited a thermal conductivity of 1.88 W/m·K and an EMI shielding effect of 52 dB. [ABSTRACT FROM AUTHOR]

Expanded graphite has promising potential environmental applications due to its porous structure and oleophilic nature, which allow it to absorb large quantities of oil. The material is produced by intercalating graphite and applying heat to convert the intercalant into gas to cause expansion between the layers in the graphite. Using different intercalants and temperature conditions results in varying properties of expanded graphite. This work has proven that the sorption properties of commercial expanded graphite differ significantly due to the material's structural and elemental characteristics, which can be attributed to the intercalation method. This resulted in various degrees of exfoliation of the graphite and possible functionalisation of the graphene sheets within the structure. This affected the material's sorption capacity and its affinity for heavy metal sorption by incorporating selectivity towards the sorption of certain metals. It was found that sample EG3, which underwent a less harsh expansion, exhibited lower porosity than EG1, and thus, the sample absorbed less oil at 37.29 g/g compared to the more expanded samples EG1 and EG2 with 55.16 g/g and 48.82 g/g, respectively. However, it was able to entrap a wider variety of metal particles compared to EG1 and EG2, possibly due to its smaller cavities allowing for a capillary effect between the graphene sheets and greater Van der Waals forces. A second possibility is that ionic or coordination complexes could form with certain metals due to the possible functionalisation of the expanded graphite during the intercalation process. This would be in addition to coordination between the metals and expanded graphite carbon atoms. The findings suggest that there is evidence of functionalisation as determined by XRD and elemental analyses. However, further investigation is necessary to confirm this hypothesis. The findings in this work suggest that the first mechanism of sorption was more likely to be related to the degree of expansion of the expanded graphite. Various metals are present in used oil, and their removal can be challenging. Some metals in oil are not considered heavy since they have a relatively low density but can be associated with heavy metals in terms of toxicity. [ABSTRACT FROM AUTHOR]

A binary porous material of SiO2 and SiO2–modified expanded graphite (MEGR) was simultaneously prepared based on a low-cost and template-free approach in which a commercially abundant sodium silicate was used as a SiO2 precursor in the presence of expanded graphite (EGR). The polycondensation and excessive aggregation of SiO2 on the surfaces of EGR enabled the formation of highly interconnected porous networks. Besides, the hydrophilicity of MEGR was improved due to the presence of multiple silanol groups from anchored SiO2. The SiO2/MEGR was then used as a binary porous support for the adsorption and stabilization of polyethylene glycol (PEG), forming composite phase change materials (CPCMs) for thermal energy storage. The prepared PEG/SiO2/MEGR CPCMs were investigated for thermal properties with varying PEG content (50–90%) and a fixed SiO2:MEGR ratio of 75:25. The presence of MEGR with desirable porous structure and improved hydrophilicity contributed to the PEG adsorption capacity of SiO2/MEGR. Indeed, the loading of PEG was improved from 60% of pristine SiO2 to 80% of SiO2/MEGR. In addition, the thermal conductivity of the 80% PEG/SiO2/MEGR composite was enhanced to 2.865 W/m K, which was 11.2 times greater than that of pure PEG. Furthermore, the PEG/SiO2/MEGR composite retained high thermal stability and excellent thermal reliability after 500 melting/crystallization cycles. The facile preparation and high thermal performance make the PEG/SiO2/MEGR composite competitive for thermal energy storage applications. [ABSTRACT FROM AUTHOR]

This comparative study experimentally investigates the effect of both the type and content of carbon based nanoparticles on the mechanical properties of epoxy composites. For this purpose, carbon nanotubes (CNTs), expanded graphite (EG), and carbon black (CB) were used as reinforcing nanoparticles at various concentrations within the epoxy polymer. The nanoparticles were dispersed by ultrasonication method. CNTs incorporated up to 0.4% by weight (wt.) while EG and CB nanoparticles were employed at 4%, 8%, 10%, and 12% concentrations by weight. Tensile tests of the nanocomposites were conducted according to ASTM D680 to determine the mechanical properties of nanocomposites including ultimate tensile strength and modulus. The results revealed that all types of nanoparticles have a strong reinforcing effect on the mechanical properties depending on their concentrations. When carbon nanotubes (CNTs) were used, the highest improvement in strength, by 84.7% at 0.1% wt., and in modulus, by 32.1% at 0.2% wt. content, was observed. EG nanoparticles exhibited improvement in both strength and modulus at all contents. The highest improvement in strength, by 109.6% at 4% wt., and in modulus, by 95.6% at 10% wt. concentration, was observed. In the case of carbon black (CB), improvement in strength was observed only at 4% wt. concentration, by 44.9%. On the other hand, enhancement in modulus was seen at all CB contents, with the greatest improvement at 10% wt., reaching 58.2%. [ABSTRACT FROM AUTHOR]

In this work, passive cooling systems for the revamping of existent silicon photovoltaic (PV) cells were developed and analysed in order to mitigate the efficiency loss caused by temperature rise in the hot season. For this purpose, expanded graphite (EG) was used to stabilize a phase change material (PCM) with a melting temperature close to 53 °C in order to realize thermal management systems (TMSs) able to store heat at constant temperature during melting and releasing it in crystallization. In particular, stearic and palmitic acid mixture (PA-SA) was shape-stabilized in EG at different concentrations (10, 12 and 14 part per hundred ratio) under vacuum into a rotary evaporation apparatus followed by cold compaction; PA-SA leakage was reduced due to its intercalation between the graphite lamellae, and the thermal conductivity necessary to maximize the heat transfer to a bulk TMS was improved via powder cold compaction, which minimizes voids and creates preferential thermal conductive patterns. The composite materials, stable till 150 °C, were tested by differential scanning calorimetry (DSC) at 1 °C/min to precisely determine the phase transition temperatures and the enthalpic content, which was only slightly reduced from 196 J/g of the neat PCM to 169 J/g due to the very low EG fraction necessary for the stabilization. Despite only the 14:100 EG-to-PA-SA ratio, the system's thermal conductivity was enhanced 40 times with respect to the neat PCM (from 0.2 to 8.3 W/(m K), value never reached in works present in the literature), with a good convergence of the values evaluated through hot disk tests and laser flash analysis (LFA), finding correlation with both graphitic content and density. In order to completely avoid leaking with the consequent dispersion of PCM in the environment during the final application, all the samples were encapsulated in a PE-made film. The mechanical properties were evaluated with compression tests at 30 °C and 80 °C simulating a possible compressive stress deriving from the contact needed to maintain the TMS position on the rear of the PV cells. Finally, the material response was simulated by imposing thermal cycles into a climatic chamber and reproducing the three hottest and coldest days of summer 2022 of two Italian locations, Verona (Veneto, 45° N, 11° E) and Gela (Sicily, 37° N, 14° E), thus highlighting the thermal management effects with delays in temperature increase and daily peak temperature smoothing. The role of EG is strategic for the processing and the properties of the resulting composites in order to realize a proper compromise between the melting enthalpy of PCM and the thermal conductivity enhancement given by EG. [ABSTRACT FROM AUTHOR]

The sliding layer created during operation of the expanded graphite–steel combination has had a huge impact on the effectiveness of the friction process, and thus on the sustainable development of society. Knowledge of the factors determining the properties of the sliding layer will make it possible to reduce friction resistance in the future through the proper design and selection of sliding pairs for given applications. This paper studies the effect of the moisture content of expanded graphite on the formation of a sliding layer on a stainless steel surface. The tests were carried out in static contact for 30 s and dynamic contact for 15 and 30 min, for loads of 10, 20, and 30 N and speeds of 25 and 50 mm/s. To determine the changes in surface geometry due to material transfer, the Ra roughness value of the surface of stainless steel samples was measured. In order to realize the purpose of the work and evaluate the effect of moist rings on the resulting sliding layer, the results of the surface roughness of stainless steel samples working with dry and moist graphite rings were compiled. The obtained results show that the presence of water in the stainless steel-expanded graphite friction node affects the formation of a sliding layer. The resulting layer reduces the surface roughness of the cooperating materials and prevents their accelerated wear. After 5 min of work with the water-soaked graphite counter-sample, depending on the applied friction conditions, a reduction in the surface roughness of the stainless steel sample was achieved in the range of 11–18% compared to the initial value. After 30 min of operation, the surface roughness decreased by 3 to 25%. Pilot studies have shown that operating conditions influence the formation of a sliding layer in the stainless steel-expanded graphite tribological contact. This confirms the validity of conducting further research in this area. [ABSTRACT FROM AUTHOR]

This study presents the development and performance evaluation of an innovative thermal energy storage (TES) system utilizing a commercially available bioderived organic phase change material (PCM) for domestic hot water production. The primary objective of this research is to enhance the efficiency and effectiveness of thermal energy storage solutions by macro-encapsulating the PCM-expanded graphite (EG) compressed modules in a multi-pass tube arrangement. A comprehensive experimental setup was employed to investigate the thermal performance of the proposed TES unit, focusing on charging and discharging cycles. Key findings reveal that conduction is the dominant mode of heat transfer, with the system achieving a significant maximum average charging power of 1440 W and a discharging power of 1990 W. The thermal energy storage capacity reached an impressive 12.6 MJ, enabling the discharge of 90 % of stored energy within 90 min. Furthermore, the exergy analysis indicated high exergy efficiencies, with charging efficiencies reaching 98 % and overall exergy efficiency at 18 %.The implications of this research are significant, demonstrating the feasibility of using bioderived organic PCM for sustainable energy applications. It highlights the potential of the modular structure of the system to integrate with heat pump and solar energy systems, thereby enhancing efficiency and sustainability in domestic hot water applications. This work significantly contributes to the advancement of sustainable thermal energy storage technologies and establishes a solid foundation for future studies aimed at optimizing TES systems for domestic hot water production.

The vacuum impregnation resin method was used to prepare composite bipolar plates in fuel cell in this study. The effects of the content of epoxy resin diluent added, temperature and pore structure of graphite on the impregnation content during the vacuum impregnation process were studied. The electrical conductivity, flexural strength and airtightness of the prepared fuel cell bipolar plates were investigated. The results show that increasing the content of diluent and temperature can reduce viscosity and increase the upper limit of resin impregnation, enabling the resin to impregnate and fill into smaller pores, while there are still some pores that cannot be filled and saturated, such as the pores below 0.1 μm are difficult to fully penetrate in the expanded graphite plate, resulting in the resin being unable to completely fill the entire pores of the expanded graphite. The optimal temperature for impregnating the epoxy resin/diluent system by vacuum impregnation is 50 ℃, and the optimal addition ratio of diluent ethylene glycol diglycidyl ether is 15%(mass fraction). The obtained bipolar plate has excellent electrical conductivity of 340.12 S/cm, flexural strength of 41.52 MPa, and helium permeability of 5.4×10-7 cm3·cm-2·s-1.

Phase change materials (PCMs) offer efficient solutions for energy sustainability. Here, we used 1-decanol, expanded graphite (EG) with high thermal conductivity, and silica aerogel (SA), which is often used for thermal insulation protection, to prepare composite PCMs (EG-PCM and SA-PCM) with stable shape through the vacuum absorption method. The leakage rate test after heat treatment determined the optimum contents of EG and SA in the composite PCMs to be 9 and 14 wt.%, respectively. Even after 220 heating/cooling cycles, the fabricated composite PCMs still maintain good thermal stability. The thermal conductivity enhancement of EG-PCM and SA-PCM to 16.09 times and 1.21 times of the neat PCM, respectively. Moreover, we tested the prepared two composite PCMs by yogurt preservation experiments in a cold chain transport portable box, which proved that they could effectively maintain the temperature and acidity of yogurt for several hours without any cooling system. Based on these results, EG-PCM and SA-PCM have broad application prospects in cold chain transport of temperature-sensitive products such as food, medicine, and vaccine. [ABSTRACT FROM AUTHOR]

TiO2/C nanocomposite films were applied on water treatment. Expanded graphite nanosheets (EG) were obtained by UVC-assisted liquid-phase exfoliation technique, without the addition of acids, surfactants, or aggressive oxidizing agents, which characterizes the process as an eco-friendly method. The carbon nanosheets were synthesized directly from graphite bulk at different times and deposited on TiO2 films surface by airbrush spray coating method, forming a TiO2/C heterojunction. The increase in the exfoliation time promoted a more efficient photocatalytic dye removal under visible light. Morphological modifications, changes in the electronic structure, and wide range of light absorption were observed from the TiO2/C heterojunction formation. The results showed that hybrid TiO2/C supported photocatalyst is a promise alternative for practical photocatalytic applications under sunlight. [ABSTRACT FROM AUTHOR]

Polyamide 11 (PA11) and copolyester (TPC-E) were compounded through melt extrusion with low levels (below 10%) of expanded graphite (EG), aiming at the manufacturing of a thermally and electrically conductive composite resistant to friction and with acceptable mechanical properties. Thermal characterisation showed that the EG presence had no influence on the onset degradation temperature or melting temperature. While the specific density of the produced composite materials increased linearly with increasing levels of EG, the tensile modulus and flexural modulus showed a significant increase already at the introduction of 1 wt% EG. However, the elongation at break decreased significantly for higher loadings, which is typical for composite materials. We observed the increase in the dielectric and thermal conductivity, and the dissipated power displayed a much larger increase where high frequencies (e.g., 10 GHz) were taken into account. The tribological results showed significant changes at 4 wt% for the PA11 composite and 6 wt% for the TPC-E composite. Morphological analysis of the wear surfaces indicated that the main wear mechanism changed from abrasive wear to adhesive wear, which contributes to the enhanced wear resistance of the developed materials. Overall, we manufactured new composite materials with enhanced dielectric properties and superior wear resistance while maintaining good processability, specifically upon using 4–6 wt% of EG. [ABSTRACT FROM AUTHOR]

In this research, to develop an efficient and magnetic graphite-based nanocomposite (Fe3O4/EG-chitosan), the natural flake graphite was first expanded to improve its active surface area. The expanded graphite (EG) was then functionalized and magnetized with chitosan and Fe3O4 nanoparticles to increase its adsorption performance. Structure of EG/chitosan and nanocomposite Fe3O4/EG-chitosan were determined and confirmed by FT-IR, XRD, EDX, FESEM, VSM, zeta potential measurement and BET surface area measurements. The surface area of EG was improved from 10.13 to 83.08 m2/g after the functionalization of it using chitosan. Fe3O4/EG-chitosan exhibited a lower magnetization saturation value (30.9 emu/g) in compared with pure Fe3O4 NPs (60.2 emu/g). The fabricated nanocomposite was then applied to adsorb BG dye from aqueous media. The optimal removal of 98% BG dye was achieved at pH 8.0, adsorbent dosage 0.04 g, initial concentration 50 ppm, and temperature 293 K. The adsorption of BG is described well with the pseudo-second order kinetic model and the Freundlich isotherm model. The results also showed that the maximum adsorption capacity of BG dye was 21.8 mg/g using the Langmuir isotherm model. In addition, after 6 adsorption-desorption cycles, the adsorption capacity of the developed Fe3O4/EXG-chitosan toward BG remains high (90%). [ABSTRACT FROM AUTHOR]

The global challenge of addressing oil spills in the ocean arises from their mobility and limited self-purification capacity, resulting in substantial and enduring harm to aquatic ecosystems and the depletion of valuable resources. Expanded graphite (EG) is a versatile and useful material that offers various unique properties and has many practical uses in industry and commerce, specifically in oil spill clean-up. This article provides a sulfur-free EG modified by palmitic acid (PA) / phosphoric acid (H3PO4). EG was synthesized by a two-step chemical oxidation process, with natural graphite flake (NGF) serving as the precursor. The chemical intercalation procedure was carried out at room temperature for 30 min in the first step "oxidation" with an optimum weight ratio of 1 g: 5.1 g: 18.8 g: 0.2 of NGF, PA, H3PO4, and KMnO4. Then, in the second step "intercalation", nitric acid, acetic acid, and potassium permanganate were utilized as assistant intercalating agents to further enhance the expanded volume of EG. FT-IR, XRD, and SEM were used to investigate the functional groups, structures, and morphology of the EG. The findings demonstrated that the interlayers within the natural flake graphite were completely opened and transformed into a structure resembling a fluffy rope, resembling the shape of a worm, upon expansion. Under optimal conditions, the maximum volume expansion achieved was 470 mL/g. The mesoporous expanded graphite, modified with PA/H3PO4, exhibits promise as an engineering material for water purification sorbents and also demonstrates a noteworthy oil sorption capacity. [ABSTRACT FROM AUTHOR]

The expanded graphite-paraffin composite phase change energy storage material was prepared by vacuum impregnation method, with expanded graphite as the main thermal material and paraffin as the phase change heat storage material. The effect of paraffin mass fraction on the microstructure, phase structure, and thermal performance of composite phase change energy storage materials were studied. The results indicate that the composite phase change energy storage material generated by the reaction of expanded graphite and paraffin mainly relies on physical adsorption and binding, and paraffin evenly covers the surface and pores of expanded graphite. When the mass fraction of paraffin is 91 %, the sealing and structural density of the composite phase change energy storage material are the best, with almost no leakage. As the mass fraction of paraffin increases, the melting point of composite phase change energy storage materials gradually increases, and the thermal decomposition temperature gradually increases. The thermal decomposition temperature of composite phase change energy storage materials with 91 % paraffin mass fraction is about 1 5 °C higher than that of phase change materials with 85% paraffin mass fraction. As the mass fraction of paraffin increases, the thermal conductivity and thermal diffusion coefficient of composite phase change energy storage materials continue to decrease, the density first decreases and then increases, and the specific heat continues to increase. When the mass fraction of paraffin is 91 %, the density of the composite phase change energy storage material is the minimum value of ()• 794 g/cm³, corresponding to a specific heat of 5.462 J/(g • K). Analysis shows that the composite phase change energy storage material with a paraffin mass fraction of 91 % has the best comprehensive performance. [ABSTRACT FROM AUTHOR]

This study is to utilize the heat-absorbing and releasing capabilities of phase change materials (PCM) to regulate the surface temperature fluctuations of batteries during charging and discharging. The goal is to keep the battery within the optimal operating temperature range. The impact of PCM thickness and phase change temperature on battery temperature is investigated by encircling a cylindrical battery with a PCM ring. To improve the thermal conductivity of PCM, expanded graphite (EG) is added to make a composite phase change material (CPCM), and the effects of various EG mass ratios on battery surface temperature and CPCM utilization level are investigated. The findings indicate that increasing PCM thickness effectively extends temperature control time, but its impact is limited. The difference in phase change temperature of PCM controls the battery temperature in different temperature ranges. Lower phase change temperatures are unsuitable for controlling battery temperature in high temperature environments. The addition of EG enhances the thermal conductivity of PCM, leading to further control of battery temperature. The results show that the addition of 6% (mass ratio) EG to CPCM extends the effective temperature control time by 11 min and improves by 28% compared to a single PCM. The CPCM utilization is also more satisfactory and achieved a balance between heat storage and thermal conductivity in a battery thermal management system (BTMS) based on PCM. [ABSTRACT FROM AUTHOR]

The solar phase change heat storage technology is concerned because it can save resources and protect environment, and meet the requirement of energy development in our country. Its intermittent and unstable characteristics increase the difficulty of its utilization. The role of phase change materials (PCM) in solar phase change heat storage is explored by simulating the cased phase change heat storage through finite element numerical analysis method. The results show that the addition of expanded graphite can substantially improve the heat storage and discharge efficiency of solar thermal accumulators. Compared with the conventional paraffin heat storage, the heat storage time of paraffin with 20% mass fraction of expanded graphite is shortened by 91.11% under the same initial conditions of inlet velocity and ambient temperature, which has the effect of enhancing heat transfer. This study provides an important reference for the development of solar water heaters, high-efficiency heat exchangers and thermal energy storage in buildings and other fields. [ABSTRACT FROM AUTHOR]

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This research endeavors to enhance the performance of nitrate salts by incorporating expanded graphite (EG) to develop efficient and sustainable energy storage solutions tailored for medium-temperature range applications. The targeted domains for application encompass industrial processes, solar cooking, and solar power generation. In order to achieve this, a composite phase change material (PCM) is developed by saturating a compressed expanded graphite (CEG) matrix with molten PCM, and CEG is created by compressing EG to achieve the desired porosity. The primary goal is to leverage expanded graphite's high thermal conductivity to improve the composite PCM's overall heat transfer capabilities. The research involves characterizing the thermal properties of nitrate salts and the composite PCM, including measurements of melting and solidification temperatures, latent heat capacity, and thermal conductivity. These measurements are carried out using established experimental techniques to ensure accuracy and reliability. Notably, the study evaluates the thermo-physical properties of PCM-CEG composites across various temperature ranges of nitrate salts. The findings reveal a significant enhancement in thermal conductivity when expanded graphite is introduced into the composite. Differential scanning calorimetry (DSC) is used to assess the effective latent heat capacity and melting temperature of the PCM-CEG composite. It is observed that the effective latent heat capacity closely corresponds to the mass fraction of PCM in the composite, and the incorporation of graphite does not significantly impact the melting temperature of the PCM.

Phase Change Material (PCM) thermal energy storage systems have emerged as a promising solution for efficient thermal energy storage from low to very high-temperature applications. This paper presents an investigation into the utilization of medium temperature range PCM-based systems for domestic hot water application, focusing on different techniques to overcome the low thermal conductivity of the PCM. Five shell and tube heat exchangers were fabricated employing different heat transfer enhancement methods including fin, expanded graphite (EG), and a combination of fin and EG. The combination of EG and circular fins exhibited the best performance in terms of charging and discharging, maintaining a uniform temperature distribution throughout the system due to extensive conductive network provided by the combination of EG and circular fins. When the PCM/EG/fin heat exchanger system is fully charged, the energy stored in the system is 109% higher than that of the PCM heat exchanger at the same elapsed time. Furthermore, the PCM/EG/fin system demonstrated a faster discharging response compared to other thermal energy storage (TES) configurations, with over 160% higher discharging power than a system without any enhancement methods. These findings emphasize the practical viability of integrating PCM/EG composite materials into thermal energy storage systems, offering a viable solution for meeting high heat demand requirements in domestic hot water applications. Furthermore, the enhanced discharging response observed in the PCM/EG/fin system has significant implications for improving energy efficiency and reducing operational costs in real-world applications.

The use of cement-based conductive mortar is an effective way to enhance the long-term operation of impressed current cathodic protection (ICCP) system. However, its widespread use is limited by the challenges of dispersing nano-fillers and the associated cost. To overcome these challenges, this study proposes the use of expanded graphite (EG) as a conductive material due to its strong conductivity, easy dispersion, and low cost. Additionally, multilayer EG flakes can promote cement hydration due to their high specific surface area, thereby improving the mechanical properties of mortar. This study examines the effects of EG content on the mechanical properties and electrical conductivity of the conductive mortar. Results reveal an exponential relation between EG content and mechanical strength, with 1.5% EG content producing the maximum mechanical properties. The resistivity of EG cement mortar decreases as the EG content increases, reaching its minimum at the percolation threshold. At this threshold, the resistivity of conductive mortar is 46.4% of the optimal content for mechanical properties (EG content is 1.5%). The incorporation of EG in cement-based conductive mortar is a viable alternative to traditional materials that can improve both conductivity and mechanical properties. This approach has great potential for enhancing the performance of ICCP systems.

Concrete is a widely used material for buildings, and its production reached approximately 10 billion m3 in 2022. Half of concrete-related buildings suffer seasonal freeze-thaw action, which causes frequent engineering damage, short service life and enormous economic loss. To improve the freeze-thaw resistance and durability of concretes, we used expanded graphite (EGC14) to encapsulate n-tetradecane (C14) and thus prepared a composite phase change material (EGC14). Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) tests indicate that the EGC14 is chemically stable and has excellent phase change capability. Then, five mass ratios of the EGC14 to concrete aggregates were designed to produce phase change concretes (PCCs), named as PCC-EGC14s (0%, 1%, 2%, 3%, and 4%). The PCC-EGC14s′ freeze-thaw resistance performances were systematically tested at different freeze-thaw cycles (FTCs). The test data demonstrate that the EGC14 could effectively keep the transition and capillary pores in the PCC-EGC14s from expanding into easily FTC-damaged macropores. Moreover, the more EGC14 the PCC-EGC14s contain, the less mass loss, and the larger dynamic moduli of elasticity (MOEd) and compressive strengths the PCC-EGC14s have. According to the strength requirement of C20 concretes, the PCC-EGC14 (3%) has the optimal freeze-thaw durability. Therefore, it is suggested for actual engineering applications. Of course, the mix design principle and experimental data of the new PCC-EGC14s in this work are helpful to comprehend the freeze-thaw process and mechanism of concretes and could also provide a critical reference for practical production.

The cooling role of phase change materials (PCMs) has emerged as a promising solution for battery thermal management systems (BTMS). However, issues such as high phase change temperature, low thermal conductivity, and easy leakage have been the long-term bottlenecks in the application of phase change materials. Herein, a composite phase change materials (CPCMs) is prepared by incorporating a mixture of lauric acid (LA) and paraffin (PA) with an expanded graphite (EG) thermally conductive unit. The mixture of lauric acid and paraffin provides latent heat, whereas expanded graphite enhances the thermal conductivity while preventing the leakage of lauric acid and paraffin. As expected, the lauric acid–paraffin–expanded graphite-based composite phase change materials demonstrate the high thermal conductivity of 1.22 W/(m k), the elevated melting enthalpy of 146.9 J/g, as well as the relatively low melting temperature of 36.1 °C. When used as a cooling system for battery thermal management systems, composite phase change materials can keep the maximum temperature of the battery below 43 °C with a temperature difference of 1.96 °C only, while ensuring the long-term cycling stability of the battery. Therefore, composite phase change materials with such a remarkable performance provide a promising and effective solution for battery thermal management systems.

This paper introduces an innovative design for an “inorganic salt-expanded graphite” composite thermochemical system. The storage unit is made of a perforated, compressed, expanded graphite block impregnated with molten CaCl2∙6H2O; the humid air passes through the holes that allow the moisture to diffuse and react with the salt. The prepared block underwent 90 hydration-dehydration cycles. Although most of the performed cycles were carried out with salt overhydration and deliquescence, the treated samples have remained mechanically and thermally stable with no drop in energy density. The volumetric energy density of the composite ranged from 135.5 to 277.6 kWh/m3, depending on airflow rate and absolute humidity. To ensure composite material cycling stability, the energy density of the block was measured during hydration at similar conditions of absolute humidity, inlet temperature, and airflow rate (0.01 kgwater/kgair, 20 °C, 400 l/min). The average energy density at these conditions was sustained at 219 kWh/m3. The block integrity was monitored by visual inspection after removing it from the reactor chamber every few cycles. Both the composite material and its manufacturing process are simple and easy to scale up for future commercialization.