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In spite of significant efforts to investigate the ability of hydrogenated and fluorinated graphene to conduct heat, little research has focused particularly upon their other thermal properties, such as thermal contraction and heat capacity, which have implications for the development of thermal nanotechnology. In an attempt to determine these thermal properties, a few experiments have been carried out, with rather conflicting results. In the present study, calculations were performed using molecular dynamics to investigate the thermal properties of graphane and fluorographene and especially the phenomena involved. The thermal expansion coefficients and heat capacities of the two-dimensional materials were determined at different temperatures. The results indicated that graphane is thermally contracted more significantly than graphene. The calculated molar heat capacity at constant volume is about 25.00 J/(mol·K) for graphene and about 29.26 J/(mol·K) for graphane. The specific heat capacity of fluorographene is always lower than that of graphane. A negative relationship does exist between the binding energy and the temperature.

The title compound, [Ni(NCS)2(C6H7N)2]n, was prepared by the reaction of Ni(NCS)2 with 4-methylpyridine in water. Its asymmetric unit consists of two crystallographically independent NiII cations, of which one is located on a twofold rotational axis whereas the second occupies a center of inversion, two independent thiocyanate anions and two independent 4-methylpyridine coligands in general positions. Each NiII cation is octahedrally coordinated by two 4-methylpyridine coligands as well as two N- and two S-bonded thiocyanate anions. One of the cations shows an all-trans, the other a cis–cis–trans configuration. The metal centers are linked by pairs of μ-1,3-bridging thiocyanate anions into [101] chains. X-ray powder diffraction shows that a pure crystalline phase has been obtained and thermogravimetry coupled to differential thermoanalysis reveals that the title compound loses half of the 4-methylpyridine coligands and transforms into Ni(NCS)2(C6H7N). Nearly pure samples of this compound can be obtained by thermal annealing and a Rietveld refinement demonstrated that it is isotypic to its recently reported Cd analog [Neumann et al., (2020). CrystEngComm. 22, 184–194] In its crystal structure, the metal cations are linked by one μ-1,3(N,S)- and one μ-1,3,3(N,S,S)-bridging thiocyanate anion into single chains that condense via the μ-1,3,3(N,S,S)-bridging anionic ligands into double chains.

The title compound, [Co(NCS)2(C6H7N)4] or Co(NCS)2(4-methylpyridine)4, was prepared by the reaction of Co(NCS)2 with 4-methylpyridine in water and is isotypic to one of the polymorphs of Ni(NCS)2(4-methylpyridine)4 [Kerr & Williams (1977). Acta Cryst. B33, 3589–3592 and Soldatov et al. (2004). Cryst. Growth Des. 4, 1185–1194]. Comparison of the experimental X-ray powder pattern with that calculated from the single-crystal data proves that a pure phase has been obtained. The asymmetric unit consists of one CoII cation, two crystallographically independent thiocyanate anions and four independent 4-methylpyridine ligands, all located in general positions. The CoII cations are sixfold coordinated to two terminally N-bonded thiocyanate anions and four 4-methylpyridine coligands within slightly distorted octahedra. Between the complexes, a number of weak C—H...N and C—H...S contacts are found. This structure represent a polymorphic modification of Co(NCS)2(4-methylpyridine)4 already reported in the CCD [Harris et al. (2003). NASA Technical Reports, 211890]. In contrast to this form, the crystal structure of the new polymorph shows a denser packing, indicating that it is thermodynamically stable at least at low temperatures. Thermogravimetric and differential thermoanalysis reveal that the title compound starts to decomposes at about 100°C and that the coligands are removed in separate steps without any sign of a polymorphic transition before decomposition.

The paper presents and discusses the results of a study of the thermal properties of cement composites with different contents of magnetite aggregate (0%, 20%, 40% and 60% by volume). The effect of grain size on the evaluated thermal properties was also investigated. For this purpose, concrete containing 50% by volume of magnetite aggregate with four different fractions (1–2 mm, 2–4 mm, 4–8 mm and 8–16 mm) was used. Thermal parameters were evaluated on specimens fully saturated with water and dried to a constant mass at 65 °C. The series with varying grain sizes of magnetite achieved thermal conductivity values in the range of 2.76–3.03 W/(m·K) and 2.00–2.21 W/(m·K) at full water saturation and after drying to a constant mass, respectively. In the case of the series with 20% magnetite by volume, the thermal conductivity was 2.65 W/(m·K) and 1.99 W/(m·K) for the material fully saturated with water and dried to a constant mass, respectively. The series with a 60% volume share of magnetite obtained values of this parameter of 3.47 W/(m·K) and 2.66 W/(m·K), respectively, under the same assumptions. [ABSTRACT FROM AUTHOR]

In recent years, three-dimensional (3D) printing has become the most popular of the additive manufacturing methods. This is because fused deposition modeling has many advantages over conventional manufacturing methods, such as enabling difficult-to-manufacture designs, producing less waste, and so forth. However, the parts produced by this method cannot be efficiently used in machine parts due to their relatively low mechanical properties. The main reason for the low mechanical properties of these parts is the poor bonding between the layers and between the fused filaments. The objective of this study is to overcome this disadvantage by implementing a heat treatment process called salt remelting. For this purpose, a remelting process was applied to 3D-printed poly(lactic acid) (PLA) samples by holding them in a pot filled with manually compressed powdered salt at 210[degrees]C for 45 min and then cooling them to room temperature in a furnace. The untreated and remelted 3D-printed PLA samples were then characterized by tensile test, three-point bending test, and hardness test to investigate the mechanical properties. The remelted samples exhibited improved mechanical properties compared to the untreated samples, and this result was attributed to the interlayer bonding and reduction of voids in the microstructure. These results were also consistent with the thermal and morphological analysis results. Highlights * This study focuses on the characterization of salt-remelted 3D-printed PLA. * Salt melt process parameters have been optimized for 3D-printed PLA. * Thermal, mechanical, tribological, and morphological properties were investigated. * It was found that the salt remelting method had a significant improving effect on the mechanical properties. KEYWORDS 3D printing, additive manufacturing, mechanical properties, structure-property relations, thermal properties, 1 | INTRODUCTION Additive manufacturing (AM) is an important manufacturing technology for a wide range of scientific and industrial processes. The term 'additive' in the name of this technology implies [...]

CrTaO4 (or Cr0.5Ta0.5O2) has been unexpectedly found to play a decisive role in improving the oxidation resistance of Cr and Ta-containing refractory high-entropy alloys (RHEAs). This rarely encountered complex oxide can effectively prevent the outward diffusion of metal cations from the RHEAs. Moreover, the oxidation kinetics of CrTaO4-forming RHEAs is comparable to that of the well-known oxidation resistant Cr2O3- and Al2O3-forming Ni-based superalloys. However, CrTaO4 has been ignored and its mechanical and thermal properties have yet to be studied. To fill this research gap and explore the untapped potential for its applications, here we report for the first time the microstructure, mechanical and thermal properties of CrTaO4 prepared by hot-press sintering of solid-state reaction synthesized powders. Using the HAADF and ABF-STEM techniques, rutile crystal structure was confirmed and short range ordering was directly observed. In addition, segregation of Ta and Cr was identified. Intriguingly, CrTaO4 exhibits elastic/mechanical properties similar to those of yttria stabilized zirconia (YSZ) with Young’s modulus, shear modulus, and bulk modulus of 268, 107, and 181 GPa, respectively, and Vickers hardness, flexural strength, and fracture toughness of 12.2±0.44 GPa, 142±14 MPa, and 1.87±0.074 MPa·m1/2. The analogous elastic/mechanical properties of CrTaO4 to those of YSZ has spurred inquiries to lucrative leverage it as a new thermal barrier material. The measured melting point of CrTaO4 is 2103±20 K. The anisotropic thermal expansion coefficients are αa = (5.68±0.10)×10−6 K−1, αc = (7.81±0.11)×10−6 K−1, with an average thermal expansion coefficient of (6.39±0.11)×10−6 K−1. The room temperature thermal conductivity of CrTaO4 is 1.31 W·m−1·K−1 and declines to 0.66 W·m−1·K−1 at 1473 K, which are lower than most of the currently well-known thermal barrier materials. From the perspective of matched thermal expansion coefficient, CrTaO4 pertains to an eligible thermal barrier material for refractory metals such as Ta, Nb, and RHEAs, and ultrahigh temperature ceramics. As such, this work not only provides fundamental microstructure, elastic/mechanical and thermal properties that are instructive for understanding the protectiveness displayed by CrTaO4 on top of RHEAs but also outreaches its untapped potential as a new thermal barrier material.

Rare earth silicates are promising environmental/thermal barrier coating (E/TBC) materials facing severe CMAS (CaO‐MgO‐Al2O3‐SiO2) corrosion. Previous studies mainly focused on the intrinsic properties of precorrosion coatings, but there were few studies on their CMAS corrosion products that play a crucial role in the performance of coatings in postservice stage. In this work, the mechanical and thermal properties of nine corrosion products between lutetium silicates and CMAS are studied using first‐principles calculations. Their differences of elastic stiffness are attributed to the different crystal structures and bonding strength. The T:O ratio is identified as a factor of the crystal structure for silicate products, and it has a good correlation with their elastic stiffness. Moreover, the divergences of thermal conductivity are dominated by three essential factors, that is, atomic vibration intensity, lattice vibrational anharmonicity, and complexity of crystal structure. Compared with rare earth silicates, six products, that is, the α‐CaSiO3, β‐CaSiO3, Ca2MgSi2O7, Ca2Al2SiO7, CaAl2Si2O8, and Ca2Lu8(SiO4)6O2, showing good damage tolerance and low thermal conductivities, are predicted to be advantageous to E/TBCs. These discoveries reveal the mechanical/thermal properties of corrosion products between lutetium silicates and CMAS and are expected to support the future researches on the performance of E/TBC in the postservice stage. [ABSTRACT FROM AUTHOR]

This study investigates the thermal conductivity (λ) and volumetric heat capacity (C) of sandy soil samples under a variety of conditions, including freeze-thaw cycles at temperatures both above and below zero and differing moisture levels. To estimate these thermal properties, a novel predictive model, EFAttNet, was developed, which utilizes custom-designed embedding and attention-based fusion networks. When compared to traditional de Vries empirical models and other baseline algorithms, EFAttNet demonstrated superior accuracy. Preliminary measurements showed that λ values increased linearly with moisture content but decreased with temperature, whereas C values exhibited a rising trend with both moisture content and freezing temperature. Following freeze-thaw cycles, both λ and C were positively influenced by moisture content and freezing temperature. The EFAttNet-based model proved highly accurate in predicting thermal properties, particularly effective at capturing nonlinear relationships among the influencing factors. Among these factors, the degree of saturation had the most significant impact, followed by the number of freeze-thaw cycles, subzero temperatures, porosity, and moisture content. Notably, dry density exerted minimal influence on thermal properties, likely due to the overriding effects of other factors or specific soil characteristics, such as particle size distribution or mineralogical composition. These findings have significant implications for construction and engineering projects, especially in terms of sustainability and energy efficiency. The demonstrated accuracy of the EFAttNet-based model in estimating thermal properties under various conditions holds promise for practical applications. Although focused on specific soil types and conditions, the insights gained can guide further research and development in managing soil thermal properties across diverse environments, thereby enhancing our understanding and application in this field. [ABSTRACT FROM AUTHOR]

Porous SiC ceramics with three different pore sizes (∼7, ∼45, and ∼98 μm) and two different porosities (∼54% and ∼63%) were prepared to investigate the effects of pore size on electrical and thermal properties of the porous ceramics. With an increase in pore size from ∼7 to ∼98 μm at the same porosity (∼54%), the electrical and thermal conductivities of the porous ceramics increased from ∼1.01 to ∼2.30 Ω−1·cm−1 and ∼14.3 to ∼26.2 W·m−1K−1, respectively. Similar trends have been obtained in the ceramics with ∼63% porosity. The porous SiC ceramic with larger pore size has smaller pore/strut interface area at the same porosity, which leads to less carrier scattering and phonon‐pore scattering at the pore/strut interfaces, resulting in higher electrical and thermal conductivities, respectively. These results suggest that the electrical and thermal properties of porous SiC ceramics can be successfully tuned by adjusting the pore size and porosity depending on the application. [ABSTRACT FROM AUTHOR]

Cubic boron nitride (cBN) has been used as a tool material for several decades due to its high hardness and thermal stability. Various binders are commonly added to cBN to synthesise cBN composites for better cutting performance. However, most studies have only investigated properties such as hardness and bulk modulus, without comprehensively studying elastic properties through experiments. In this study, the sound velocities and elastic properties of cBN with AlN binder were determined by using the ultrasonic interferometry technique. The bulk and shear moduli with their pressure dependence were determined as B 0 = 351 (3) GPa, G 0 = 344 (3) GPa, B 0 ′ = 4.32 (4) and G 0 ′ = 1.74 (2) using the finite strain equation-of-state approaches. Elasticity-related thermal properties, such as Debye temperature, Grüneisen parameter, thermal conductivity and coefficient of thermal expansion were also estimated. The results show that the elastic properties of the cBN composite with vol. 8.8% AlN-binder are comparable to the pure cBN compact. Additionally, the thermal conductivity and coefficient of thermal expansion have little effect on cBN composite with AlN binder compared to pure cBN. [ABSTRACT FROM AUTHOR]

In this study, the impacts to soil thermal properties during and after biocementation via microbially induced calcite precipitation (MICP) method on silty silica sand specimens with varying fines content (0%, 5%, and 15%) were investigated. Firstly, calcium conversion was measured after each pulse; then, the MICP-treated specimens were tested for cementation uniformity. The evolution of thermal conductivity of silty soils with the MICP treatment was assessed using a thermocouple probe. The results show that thermal conductivity of silty saturated sands increased by 17% for specimens treated to 9.7% CaCO3. The improvement in thermal conductivity was attributed to the formation of calcium carbonate bridges binding the soil grains together. The results suggested that the thermal conductivity of silty soil depends on water content, the number of treatment pulses, and the treatment uniformity through the soil specimen. Presence of fines content in the soil was found to play an important role in the distribution and uniformity of biocementation through the soil specimen. However, no statistically significant difference in the thermal conductivity values of MICP-treated specimens with different fines content was observed (p>0.05). The average calcium carbonate content ranged between 10.7% and 7.2% for the soils with 0% and 15% fines content, respectively. The findings of this research could be used to improve the efficiency of geothermal boreholes and other energy geostructures using MICP by improving thermal conductivity of dry and partially saturated soil. [ABSTRACT FROM AUTHOR]

Reaction of Co(NCS)2 with 4-methylpyridine N-oxide in methanol leads to the formation of crystals of the title compound, [Co2(NCS)4(C6H7NO)4(CH4O)2] or Co2(NCS)4(4-methylpyridine N-oxide)4(methanol)2. The asymmetric unit consist of one CoII cation, two thiocyanate anions, two 4-methylpyridine N-oxide coligands and one methanol molecule in general positions. The H atoms of one of the methyl groups are disordered and were refined using a split model. The CoII cations octahedrally coordinate two terminal N-bonded thiocyanate anions, three 4-methylpyridine N-oxide coligands and one methanol molecule. Each two CoII cations are linked by pairs of μ-1,1(O,O)-bridging 4-methylpyridine N-oxide coligands into dinuclear units that are located on centers of inversion. Powder X-ray diffraction (PXRD) investigations prove that the title compound is contaminated with a small amount of Co(NCS)2(4-methylpyridine N-oxide)3. Thermogravimetric investigations reveal that the methanol molecules are removed in the beginning, leading to a compound with the composition Co(NCS)2(4-methylpyridine N-oxide), which has been reported in the literature and which is of poor crystallinity.

Faraday isolators can prevent the front-end system from disturbance and damage caused by a back-reflected beam, so they are important elements in laser systems. As magneto-optical materials are the most important component in Faraday isolators, the studies on magneto-optical materials have attracted much attention these years. Tb3Al5O12 (TAG) ceramics are considered to be one of the most promising magneto-optical materials for visible to near-infrared wavelength band application because of their outstanding comprehensive magneto-optical performance. However, the optical quality of TAG ceramics needs further optimization to meet the application requirements. In this work, high optical quality (Tb1−xYx)3Al5O12 (x = 0, 0.05, 0.1, 0.2, and 0.3) magneto-optical ceramics were fabricated successfully by solid-state reaction sintering combined with hot isostatic pressing (HIP) post-treatment. All the ceramics obtained showed a single garnet phase for different values of x in the range studied. The addition of Y2O3 was found to suppress the secondary phase and improve optical quality significantly. The ceramic samples obtained had clear grain boundaries and possessed the in-line transmittance values of 82.9% at 1064 nm and 82.2% at 633 nm, respectively. The Verdet constants of (Tb1−xYx)3Al5O12 ceramics with x = 0, 0.05, 0.1, 0.2, and 0.3 were −188.1, −175.4, −168.5, −143.0, and −119.9 rad/(T·m), respectively. The thermal conductivity of TAG ceramics was found to be 5.23 W/(m·K) at 25 ℃, and when 20% Y was substituted in place of Tb, the thermal conductivity decreased by only 9.4%.

Full Potential Linearized Augmented Plane Wave method (FP-LAPW) was employed to investigate the behavior of cubic perovskite CsBeO3 under the influence of pressure. The spin polarized study has been carried out in PBE-GGA approximation under the application of pressure. The variation of pressure is attained by the appropriate reduction of volume for the compound. At equilibrium volume and at 0 GPa, the compound CsBeO3 is found to exhibit energy gap in the spin up direction and the spin down direction is largely conducting. With the reduction of volume and their corresponding increase in pressure, the electronic behavior changes for the compound. At a pressure of about 10 GPa, the s-orbital of Cs atom undergoes energy excitation to higher energy level due to an ordered dispersive effect at s-orbital. This results in the disappearance of energy gap and the compound becomes conducting in spin up direction and the half metallic ferromagnetism is found to disappear at increased pressure. Thermal properties such as Debye temperature and Curie point have been reported in this work. Elastic constants and anisotropy factor have been determined and compared at different pressures.

Si3N4 ceramics with high mechanical properties and thermal conductivity, exhibiting fine and bimodal microstructure, were prepared by adjusting the Er2O3/MgO ratio and hot‐pressing sintering at 1800°C for 4 h. The microstructure, grain distribution, lattice oxygen content, mechanical properties, and crack propagation process of the sintered bulk samples were systematically investigated. It was found that a low Er2O3/MgO ratio contributed to the densification of Si3N4 ceramics, whereas a high Er2O3/MgO ratio favored the grain growth of Si3N4 ceramics. In this research, the grain size distribution and average diameters as well as their impact on mechanical properties were examined. When the ratio of Er2O3/MgO was 3:1, Si3N4 had a larger average diameter and higher thermal conductivity, but the mechanical properties were somewhat reduced. When the ratio of Er2O3/MgO was 2:2, the sample displayed enhanced mechanical performance, which can be explained by the formation of a bimodal structure. The research indicates that it is feasible to control the microstructure and optimize the mechanical properties of Si3N4 ceramics by tailoring the sintering additives. [ABSTRACT FROM AUTHOR]

Ceramic thermal barrier coatings (TBCs) with high toughness and low thermal conductivity are important for developing aero engines with high thrust‐to‐weight ratio and thermal efficiency. In this work, the properties of tantalate Y1/6Yb5/6TaO4 (YYT) were optimized by introducing 8 wt.% yttria‐stabilized zirconia (8YSZ), synthesized using spark plasma sintering, as a second‐phase ceramic. The highest toughness (3.57 MPa m1/2) of the YYT/8YSZ composite ceramics was due to multiple toughening mechanisms. The underlying mechanisms of these processes were revealed based on the microstructures and residual stress of the YYT/8YSZ composite ceramics. A shift from an intergranular fracture to a transgranular fracture was caused by the difference between soft‐grain YYT and hard‐grain 8YSZ, which consumed the fracture energy. Furthermore, the formation of microcracks, crack deflection, bridging, and branching were analyzed based on the differences in Young's moduli and thermal expansion coefficients of YYT and 8YSZ. Internal defects and weak connections between the YYT and 8YSZ grains reduced the thermal conductivity of the composites until it reached its lowest value at 1.4 W m−1 K−1. The studied toughening mechanisms could be applied to various composites. Moreover, herein, we provide a new strategy to design and synthesize TBCs with enhanced performance. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation of nanocomposites composed of three ratios of epoxy/graphene nanoplatelets (GNPs) by weight. The 0.1, 0.2, and 0.3 wt.% specimens were carefully manufactured, and their mechanical and thermal conductivity properties were examined. The tensile strength and modulus of epoxy/GNPs were enhanced by the large surface area of graphene nanoplatelets, causing crack deflection that created new fracture fronts and friction because of the rough fracture surface. However, the compressive strength was gradually reduced as GNP loading percentages increased. This was probably due to severe plastic yielding on the epoxy, leading to catastrophic axial splitting caused by premature fractures. Furthermore, the highest thermal conductivity was 0.1283 W/m-K, representing a 20.92% improvement over neat epoxy (0.1061 W/m-K) when 0.3 wt.% GNPs were added to the epoxy. This was because of efficient heat propagation in the GNPs due to electron movement through percolative paths. The tensile failure mode in epoxy/GNP nanocomposites showed a few deflected and bifurcated rough cracks and brittle, dimple-like fractures. Contrarily, compressive failure mode in GNP-added epoxy showed plastic flexural buckling and brittle large-axial splitting. The epoxy/GNP nanocomposites were considered a damage-tolerant material. [ABSTRACT FROM AUTHOR]

We thoroughly investigated the structural, mechanical, electronic, vibrational, optical, thermodynamic, and a number of thermophysical properties of W2N3 compound through first-principles calculations using the DFT based formalism. The calculated structural parameters show very good agreement with the available theoretical and experimental results. The mechanical and dynamical stabilities of this compound have been investigated theoretically from the elastic constants and phonon dispersion curves. The Pugh's and Poisson's ratios of W2N3 are located quite close to the brittle/ductile borderline. W2N3 is elastically anisotropic. The calculated electronic band structure and density of states reveal that W2N3 is conducting in nature. The Fermi surface topology has also been explored. The analysis of charge density distribution map shows that W atoms have comparatively high electron density around compared to the N atoms. Presence of covalent bondings between W–N, W–W, and N–N atoms are anticipated. High melting temperature and high phonon thermal conductivity of W2N3 imply that the compound has potential to be used as a heat sink system. The optical characteristics show anisotropy. The compound can be used in optoelectronic devices due to its high absorption coefficient and low reflectivity in the visible to ultraviolet spectrum. Furthermore, the quasi-harmonic Debye model is used to examine temperature and pressure dependent thermal characteristics of W2N3 for the first time.

BackgroundU3Si2 is regarded as one of the most promising accident-tolerant nuclear fuels for light water reactors and is expected to replace the UO2 nuclear fuel in the future. Currently, spark plasma sintering (SPS) is an advanced technique for preparing U3Si2 pellets; however, the influence of SPS parameters on the performance of the pellets is unclear.PurposeThis study aims to investigate the effects of different sintering parameters (temperature and pressure) on the mechanical and thermal properties of the U3Si2 pellets prepared using SPS technology.MethodsThe thermal diffusivity of U3Si2 pellets was measured using a laser flash apparatus, and the thermal conductivity of the pellets was calculated. The mechanical properties of the pellets, including hardness, Young's modulus, and fracture toughness, were measured using nanoindenter. Thereafter, the influence of different sintering temperatures in the range of 1 000~1 300 ℃ and pressures in the range of 30~90 MPa on the mechanical and thermal properties of U3Si2 pellets were carefully examined.ResultsThe measurement results show that the thermal conductivity of the as-synthesized pellets increases linearly with temperature in the range 27~700 ℃. Moreover, increasing the sintering temperature and pressure improves the thermal conductivity of the U3Si2 pellets. The hardness and Young's modulus of the pellets increase with an increase in sintering temperature. They also exhibit a trend of first increasing and then stabilizing with increasing pressure, and tend to fully stabilize at 60 MPa. Moreover, the fracture toughness of the pellets decreases with the increase of sintering temperature and increases with increasing pressure.ConclusionsBased on the above results, optimized SPS parameters for the U3Si2 pellets are proposed, and this study provides a reference for the preparation of high-performance U3Si2 pellets.

Purun fiber (PF), which has been used as a raw material for handicrafts, can be used as a filler in composite materials. The purpose of this study is to determine the characteristics of polyester composites with the addition of PF filler at concentrations (5, 10, and 15 %) with arrangements, namely parallel, random, and woven. In this study, the method used was the press molding method with a size of 20 × 20 × 0.3 cm. The resulting composite was analyzed for functional groups, physical properties, morphological properties, mechanical properties, and thermal properties. The functional group results of PF treatment showed a sharp absorption at wave numbers 1724–2983 cm−1, indicating the presence of C=C vibrations in the aromatic ring. For all fiber arrangements, the addition of 10 % PF resulted in the best composite structure. The results of the highest composite physical properties include density, water absorption, and thickness swelling of 0.958 g/cm−3, 10.079 %, and 24.57 × 10−3, respectively. The results of the highest composite mechanical properties are tensile strength, tensile modulus, elongation, and flexural strength of 813.9519 MPa, 9345.737 MPa, 14.06 MPa, and 58.8399 MPa, respectively. While the results of the thermal properties that can be seen from the percent weight loss of the composite obtained the best results in random samples with a variation of 10 %, the effect of the PF filler ratio on composite heat flow obtained the best results, namely in samples parallel to 5 % with a temperature of 500.87 °C. It can be summarized that PF has the potential as a filler in the manufacture of composites.

The acoustic and thermal properties were determined for biodegradable insulation materials produced from desilicated wheat straws with two different fungi and three different incubation periods. Ganoderma lucidum (GL) and Pleurotus ostreatus (PO) fungi and wheat straw were exposed to fungal incubation for 10, 20, and 30 days to produce mycelium-based insulation materials. The sound absorption coefficients of mycelium-based insulation boards produced using PO fungus were higher than those produced with GL fungus. It was found that the acoustic absorption coefficients of insulation boards produced using PO fungus at 1,000 Hz were 87 to 99% according to the incubation periods. The sound transmission losses of mycelium-based insulation boards produced ranged from 46.4 to 59.7 dBa at 1000 Hz. The group of boards labeled as YP2 exhibited the lowest level of sound transmission loss, whereas GL2 revealed the highest degree of sound transmission loss at 1000 Hz. The lowest thermal conductivity coefficient was obtained in insulation boards produced with PO fungus and an incubation period of 20 days. The limiting oxygen index (LOI) value of mycelium-based insulation materials was considerably higher than the insulation boards commonly used today. Thermogravimetric analysis and derivative thermogravimetry curves of mycelium-based insulation materials were also determined.

Building material manufacturers must support new production models that encourage the manufacture of more efficient and sustainable products. This includes thinking about savings in the use of raw materials, a contribution to the energy efficiency of buildings during their useful life, and a reduction in the generation and deposit of waste in landfills. In this research, an analysis of the thermal properties of gypsum composites added with plastic waste is carried out using the most common methods, the steady state method and the transient plane source method, and the effect of water saturation on these composites is tested. The results show an improvement in the thermal performance of the composites (values reduced with respect to the reference by 4–7%), despite their heterogeneity, as well as a variation in the measurements carried out, depending on the method used for the measurements (variation up to 10%). It is also found that the degree of humidity negatively affects the thermal conductivity coefficient but, on the contrary, this coefficient is not altered in the composites with plastic waste, due to their lower hygroscopicity. Therefore, it is considered that the proposed eco-plasters are a good alternative to traditional plasters, with which to contribute to the achievement of the objectives of the current European directives on waste and circular economy. [ABSTRACT FROM AUTHOR]

Molten salt-based nanofluid is a thermal storage and heat transfer medium for concentrated solar thermal power plants formed by adding nanoparticles to molten salt, which can enhance the thermal performance of molten salt. However, the nanoparticles tend to aggregate in nanofluids, causing changes in thermal properties. In this work, molecular dynamics simulations were used to study the effect of morphological characteristics of aggregates on the thermal conductivity and specific heat capacity of molten salt-based nanofluids. The results show that the aggregated nanoparticles cause a greater increase in thermal conductivity and specific heat capacity than dispersed nanoparticles. Additionally, the increase in fractal dimension leads to thermal conductivity reduction, while there is no clear correlation between the fractal dimension and specific heat capacity. New insights into the thermal properties of aggregated nanofluids are provided by analyzing the contribution of material components, heat flux fluctuation modes, and energy compositions. It is found that the thermal conductivity of aggregated nanofluids is mainly dominated by the base liquid and collision term. However, the specific heat is not related to the variation in the contribution of different energy compositions. Moreover, compared to the dispersed nanofluid, the increased specific heat capacity of aggregated nanofluids is attributed to the thicker semi-solid layer. This study provides guidance for the design and control of the thermal properties of molten salt-based nanofluids. [ABSTRACT FROM AUTHOR]

To find a low temperature phase change material (PCM) that can be applied to the middle constant temperature chamber of the three chamber refrigerator, this study proposes a binary eutectic PCM of n-decanol and capric acid as a base liquid, expanded graphite as a support material, and boron nitride as a thermal conductivity enhanced particle to modify the material. The composite PCM with suitable phase change temperature and high phase change latent heat is prepared by the solution blending method. The leakage rate experiment determines the maximum adsorption ratio of expanded graphite to be 92 %. The chemical structure, microstructure and thermodynamic properties are characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, scanning electron microscopy, thermal conductivity analyzer and thermogravimetric analyzer. The results show that the n-decanol and capric acid binary eutectic PCM is fully wrapped in the porous structure of expanded graphite, and boron nitride thermal conductivity enhanced particles are well adsorbed on the surface and pores of expanded graphite. The n-decanol and capric acid phase change material, boron nitride thermal conductivity enhanced particles and expanded graphite support material are only physically combined and no chemical reaction occurred. The phase change temperature of CPCM-2 with 3 % boron nitride thermal conductivity enhanced particles is -3.68 °C, the phase change latent heat is 129.2 J/g, and the thermal conductivity is 0.75 W/m·K. It has good thermal stability and reliability in the application temperature range.

PM2.5 filters with hydrophobicity and thermal resistance are preferable for automobile cabins, engine air intake, and indoor applications, safeguarding against moisture ingress, microbial growth, and temperature fluctuations, and ensuring optimal air quality. This study explored the effects of blending five fibres with different web arrangements and fibre blend compositions on needle-punched dust-holding, hydrophobic, and thermal properties. Polyphenylene sulfide (PPS), polypropylene (PP), polyester (PET), polylactic acid (PLA), and polyacrylonitrile (PAN) were blended in different proportions to produce the samples. The method included opening, blending, carding, web laying, and needle punching to produce eight samples with cross-laid, parallel-laid, and pre-needled parallel-laid web configurations. Standard test methods were employed for the characterization. The results showed a dust holding capacity of > 3,423,000 particles/cm2, the highest WCA of 133.12°, and the highest thermal resistance of 0.24255 m2KW−1. Based on the ANOVA analysis, web arrangement and pre-needling did not have a significant impact on the hydrophobicity of the samples. N0, N1, and N2 showed similar high water contact angles (~ 126°), indicating that the hydrophobicity was more affected by the chemistry of the fibre blend than by the web structure. Turkey’s analysis of other samples strengthened this idea. However, they had a substantial impact on the porosity, air permeability, dust-holding capacity, and thermal properties at a P-value ≤ 0.05. The findings provide insightful information regarding the complex interactions among fibre content, web layout, and pre-needling to develop sophisticated needle-punched PM2.5 filters.

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