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This study describes the preparation and characterization of PVP-PEO nanofibers filled with PbS nanoparticles. The effect of polymer concentrations, surface morphology, and diameter distribution studies of the nanofibers was evaluated by Scanning Electron Microscopy (SEM). The SEM images revealed that smooth and homogeneous nanofibers could be achieved at 12% PVP-PEO (50:50 wt%) concentration. The XRD and TEM analysis confirmed the formation of PbS nanoparticles in the PVP-PEO blend matrix, which also revealed the high crystalline behaviour of the PbS nanoparticles. The XRD data showed that the intensity and average crystallite size increase with PbS concentration. The FTIR and TGA studies revealed the interaction between PbS nanoparticles and the PVP-PEO blend matrix. UV–Vis diffuse reflectance studies have shown that the reflectance onset shifted toward a blue shift than bulk PbS. The optical bandgap determined using the Kubelka-Munk function lies 1.08–1.56 eV range by varying PbS concentration. [ABSTRACT FROM AUTHOR]

An accurate estimation of the effective thermal conductivity of various insulation materials is essential in the evaluation of heat leak and boil-off rate from liquid hydrogen storage tanks. In this work, we review the existing experimental data and various proposed correlations for predicting the effective conductivity of insulation systems consisting of powders, foams, fibrous materials, and multilayer systems. We also propose a first principles-based correlation that may be used to estimate the dependence of the effective conductivity as a function of temperature, interstitial gas composition, pressure, and structural properties of the material. We validate the proposed correlation using available experimental data for some common insulation materials. Further improvements and testing of the proposed correlation using laboratory scale data obtained using potential LH 2 tank insulation materials are also discussed. [Display omitted] • We develop physics-based insulation property models for cryogenic LH 2 storage tank • Model captures the micro- and macro-features of the insulation system with any gas • We demonstrate the applicability of model to several typical insulation materials • Model performs well against experiment even at extended pressure/temperature range • Model parameters can be evaluated from either physics or experimental measurements [ABSTRACT FROM AUTHOR]

Natural ester is regarded as a potential alternative to mineral insulating oil and has a wide range of applications in power system, but its electrical properties and thermal conductivity still need to be improved. Nano modification technology can improve the performance of natural ester to ensure the stability and reliability of natural ester in power equipment. In this study, nano modified natural ester is prepared with APTES surface modified h-BN, and the mechanism of enhancing the properties of natural ester is explored from the microscopic perspective by molecular simulation. The experimental results showed that nano h-BN had good dispersion stability in natural ester after surface modification with APTES. The electrical properties and thermal conductivity of the nano modified natural ester have been greatly improved, and the relative optimal doping concentration of nanoparticles is 0.03 g/L. The simulation results show that the interfacial thickness between nanoparticles and natural ester is larger and more tightly bound after surface modification, which is beneficial to reduce thermal resistance and improve thermal conductivity of natural ester insulating oil. The traps at the interface between nanoparticles and natural ester can capture free electrons in the oil, thus improving the breakdown voltage of natural ester insulating oil. [ABSTRACT FROM AUTHOR]

To improve the ablation resistance under long-time working conditions, a multiple interface nozzle with a carbon ceramic throat cap and a copper infiltrated tungsten throat insert is designed. Firstly, a transient numerical model on thermochemical erosion (considering surface reactions of carbon and tungsten) of the multiple interface nozzle in a hybrid rocket motor is established, and the regression of nozzle inner profile is simulated by adopting a dynamic grid technique. Then a 200 s firing test of the full-scale hybrid rocket motor with the multiple interface nozzle is conducted, and 98% hydrogen peroxide and hydroxyl-terminated polybutadiene based fuel are adopted. Erosion steps are formed at the interface of the carbon ceramic and copper infiltrated tungsten, and its formation mechanism is discussed. The erosion step height on the windward side of the throat insert is larger than that on the leeward side of the throat insert. The nozzle inner profile after the test agrees well with the simulation results, and the error of the nozzle throat diameter between the simulation results and test data is about 3.45%, which verifies the accuracy of numerical models. Finally, effects of erosion steps on the ablation characteristics and thermal protection properties are studied by numerical simulations. The results indicate that the erosion rate on the leeward side is much lower than that on the windward side. On the leeward side, the obvious radial diffusion of the gas occurs and the erosion rate increases with the increase of the erosion step height. Local vortices at the position of erosion steps will improve the heat transfer coefficient. When the erosion step height increases, the temperature on the outside surface of the nozzle shell improves, and it is increased by 38.3 K on the shell surface in the nozzle throat at t = 200 s. Research findings in this paper can provide important support for the engineering application of hybrid rocket motors with multiple interface nozzles. • Transient simulations on thermochemical erosion of C and W are performed. • 200 s firing test of hybrid rocket motor with multiple interface nozzle is conducted. • Simulation results agree well with test data and erosion step is found. • Erosion rate on the leeward side is much lower than that on the windward side. • Nozzle shell temperature increases with the increase of erosion step height. [ABSTRACT FROM AUTHOR]

A new type of non-oxide sintering additive of YH 2 was introduced for the fabrication of AlN ceramics with high thermal conductivity and flexural strength. The effects of YH 2 addition (0–5 wt%) on the phase composition, densification, microstructure, thermal conductivity and flexural strength of pressureless sintered AlN ceramics were investigated and compared with those Y 2 O 3 -added samples (1–5 wt%). The addition of 1 wt% YH 2 led to an in-situ reduction reaction with oxygen impurities, the formation of Y 2 O 3 and finally the formation of yttrium aluminate, which in turn improved densification and microstructure. A high flexural strength (408.69 ± 28.23 MPa) was achieved. The addition of 3 wt% YH 2 increased the average grain size and purified the lattice. All these effects are believed to help achieve a high thermal conductivity of 184.82 ± 1.75 W·m−1·K−1. Although the thermal conductivity was close to the value of 3 wt% Y 2 O 3 -added sample, its strength was much increased to 381.53 ± 43.41 MPa. Meanwhile, it demonstrated a good combination of the thermal conductivity and flexural strength than the values reported in some literature. However, further increasing the YH 2 addition to 5 wt% resulted in a high N/O ratio that inhibited the densification behavior of AlN ceramics. The current study showed that AlN ceramics with excellent thermal and mechanical properties could be obtained by the introduction of a suitable YH 2 additive. [ABSTRACT FROM AUTHOR]

In this paper, a series of high-entropy rare earth niobates, including fluorite RE 3 NbO 7 (HE317), monoclinic RENbO 4 (HE114) and RENbO 4 /RE 3 NbO 7 composite (HE-composite), are prepared via solid state reaction, following by a study about their thermal and mechanical properties. The high-entropy rare earth niobates exhibit excellent phase stability after thermally exposed to 1300 °C for 100 h, indicating entropy can stabilized high-entropy rare earth niobates. Compared with the single element rare earth niobates, high-entropy rare earth niobates have higher fracture toughness and hardness. The high-entropy RENbO 4 /RE 3 NbO 7 composite has the best mechanical properties, with a fracture toughness of 2.71 ± 0.17 MPa·m1/2 and hardness of 9.46 ± 0.24 GPa, respectively. The high-entropy niobates exhibit high coefficients of thermal expansion which is close to 7 wt% Y 2 O 3 stabilized ZrO 2. It is also proved that the configurational entropy has little effect on the critical temperature from monoclinic to tetragonal phase transition. The thermal conductivity of HE-composite is lower than HE114, indicating the combination of HE114 and H317 is a more efficient strategy to decrease the thermal conductivity of HE114 than entropy engineering. [ABSTRACT FROM AUTHOR]

First principles calculations were conducted on (HfTiWZr)B 2 high entropy diboride (HEB) composition, which indicated a low formation energy and promising mechanical properties. The (HfTiWZr)B 2 HEBs were synthesized from the constituent borides and elemental boron powders via high energy ball milling and spark plasma sintering. X-ray diffraction analyses revealed two main phases for the sintered samples: AlB 2 structured HEB phase and W-rich secondary phase. To investigate the performance of multi-phase microstructures containing a significant percentage of the HEB phase was focused in this study. The highest microhardness, nanohardness, and lowest wear volume loss were obtained for the 10 h milled and 2050 °C sintered sample as 24.34 ± 1.99 GPa, 32.8 ± 1.9 GPa and 1.41 ± 0.07 × 10−4 mm3, respectively. Thermal conductivity measurements revealed that these multi-phase HEBs have low values varied between 15 and 23 W/mK. Thermal gravimetry measurements showed their mass gains below 2% at 1200 °C. [Display omitted] [ABSTRACT FROM AUTHOR]

Si 3 N 4 -TiN composites have extensive manufacturing applications because of their first-rate mechanical and thermal properties. Conversely, they are very demanding on machines that use conventional practices because of their superior strength and hardness. Electrical discharge machining is a viable substitute for machining of Si 3 N 4 -TiN composites through electrical erosion. However, very few studies have been conducted on the machinability and surface characteristics of electrical-discharge-machined composites. This study focuses on the materials processing characteristics of a Si 3 N 4 -TiNcomposite using rotary EDM and die-sinking EDM performed with a Cu electrode. In addition, the surface and cross section of the subsurface of the composite were examined, along with energy dispersive X-ray analysis, to identify the elements present on the machined surface. It was found that the high level of hardness and low level of toughness of the Si 3 N 4 -TiN composite contributed to the presence of microcracks, globules, pores, recast layers, and craters on the EDMed surface. The recast layer thicknesses of the die-sinking EDM (optimum hole, 106 μm; best hole, 151 μm; worst hole, 166 μm) and rotary EDM (optimum hole, 53 μm; best hole, 55 μm; and worst hole, 58 μm) were examined. In addition, the presence of pores and ablation increased significantly during the rotary EDM process. Rotary EDM parameters capable of producing a minimum white layer thickness were also investigated. Finally, the porosity levels were estimated according to the number of pores using ImageJ software. For the die-sinking EDM, the estimated porosity values for the optimum, best, and worst holes were 14.989%, 19.525%, and 21.706% respectively and for the rotary EDM, these values were 24.873%, 33.04%, and 37.99% respectively. [ABSTRACT FROM AUTHOR]

The porous silicon carbide ceramics with multilevel directional pores were prepared by chemical vapor infiltration (CVI) combined with sacrificial template method. Carbon fiber preform with specific structure was used as template, and silicon carbide was deposited by CVI process. Then, the carbon fiber template was oxidized and removed, so that the porous silicon carbide ceramics were obtained. The influence of deposition time on pore structure, mechanical properties and thermal properties was studied. Compared with the traditional pore-making process, the pores formed by sacrificial template method are more regular, which brings excellent mechanical properties and thermal insulation properties. The porosity and flexural strength of the sample deposited for 72 h can reach 66.00% and 67.52 MPa, respectively, the thermal conductivity can be kept below 1 W/(m·K) from room temperature to 1200 °C. [ABSTRACT FROM AUTHOR]

Electronic packaging materials should integrate with excellent overall performance including thermal, mechanical, and machinability to meet the challenges of the current highly integrated development of the electronics industry. The low-temperature sintering of high-strength 3D-SiC frameworks with equiaxed grains was achieved at 2250 °C by regulating the contents and particle size of coarse and fine powders in bimodal SiC hybrid particles. And 3D-interpenetrated network structures SiC/Al (SiC 3D /Al) composites for electronic packaging were then fabricated using a vacuum/gas pressure infiltration Al alloys process. Results indicated the thermal conductivity (TC), coefficient of thermal expansion (CTE), and thermal deformation parameter (TDP) of the composites were improved with increasing coarse powder size. And SiC 3D /Al with the coarse powder size of 38 μm and the coarse powder content of 60 wt% achieved the compatibility of optimal thermophysical and mechanical properties with flexural strength of 406.14 MPa, CTE of 5.38 × 10−6/K, TC of 230.03 W m−1 K−1, and TDP of 0.023 matching that of Si. A further increased coarse powder particle size to 48 μm and higher 58 μm reduced the mechanical properties by 14% and 22%, respectively. Moreover, the composites maintained stable CTE and TC after 100 thermal cycles, and 3D-SiC framework was free of defects and no interfacial debonding, ensuring long-term service reliability. Integration of distinguished overall performance was primarily implemented by the synergistic effect of the 3D network framework with equiaxed grains mutual strong bonding as well as the clean and well-bonded interface. This technology provides a reference for the design and synthesis of high-performance electronic packaging materials with scalability and tuneability. [ABSTRACT FROM AUTHOR]

This article aims to illustrate the influence of the composite micro-powder of α-Al 2 O 3 and zirconium basic carbonate (ZBC) on the microstructure, mechanical and thermal properties, and slag resistance of corundum castable. The results show that the addition of the composite micro-powder to corundum castable sintered at 1550 °C optimized its pore structure, which presented an apparent porosity of 16.8% and a slump in pore size from 10.80-45.72 μm to 0.36–1.83 μm. The ZrO 2 dissolving from ZBC combined with corundum matrix to form "intergranular" and "intragranular" submicron structures, which promoted the densification of matrix structure and improved the strength of castable by 25.8%–42.9%. In terms of slag resistance, castable with composite micro-powder saw an absorption of liquid slag in micropores and a Cr-rich complex spinel blocking layer with high melting point during slag erosion. Moreover, the in-situ ZrO 2 could enter slag to boost its viscosity, thus inhibiting the penetration capacity. Consequently, the penetration and erosion ratios of castable reduced by 6.32% and 83.99%, respectively. [ABSTRACT FROM AUTHOR]

Monolithic Al 2 O 3 and Al 2 O 3 -graphene-SiC hybrid composites were prepared by spark plasma sintering (SPS) under vacuum atmosphere. The results show that the hybrid composites were almost completely dense (>97%). SiC content has a significant effect on the microstructure of the composites. With the increase of SiC content, the average grain size of alumina decreased gradually. The addition of SiC to alumina changed fracture mode from inter-granular fracture to mixed fracture mode of inter-granular fracture and trans -granular fracture. The Al 2 O 3 -0.4 wt%graphene-5 wt% SiC hybrid composite has the highest bending strength and hardness, which were 57% and 19.22% higher than those of the monolithic alumina, respectively. The room temperature (RT) thermal conductivity of the monolithic Al 2 O 3 (25.5 W/m·K) was the highest. The thermal conductivity and thermal diffusivity coefficient of the composites decreased with the increase in temperature, while the specific heat of monolithic alumina and composites increased with the increase in temperature and additives. These properties were related to the microstructure of materials and the possible transport mechanisms were discussed. [ABSTRACT FROM AUTHOR]

Thermal barrier coatings with excellent thermal performance and corrosion resistance are essential for improving the performance of aero-engines. In this paper, (Y 3-x Yb x)(Al 5-x Sc x)O 12 (x = 0, 0.1, 0.2, 0.3) thermal barrier coating materials were synthesized by a combination of sol-gel method and ball milling refinement method. The thermal properties of the (Y 3-x Yb x)(Al 5-x Sc x)O 12 ceramics were significantly improved by increasing Yb and Sc doping content. Among designed ceramics, (Y 2.8 Yb 0.2)(Al 4.8 Sc 0.2)O 12 (YS-YAG) showed the lowest thermal conductivity (1.58 Wm−1K−1, at 800 °C) and the highest thermal expansion coefficient (10.7 × 10−6 K−1, at 1000 °C). In addition, calcium-magnesium- aluminum -silicate (CMAS) corrosion resistance of YS-YAG was further investigated. It was observed that YS-YAG ceramic effectively prevented CMAS corrosion due to its chemical inertness to CMAS as well as its unique and complex structure. Due to the excellent thermal properties and CMAS corrosion resistance, YS-YAG is considered to be prospective material for thermal barrier coatings. [ABSTRACT FROM AUTHOR]

Understanding pressure-induced acoustic velocity-elasticity behavior has extraordinary significance in the fields of materials science and earth science. Herein, we used an advanced high-pressure high-temperature (HPHT) method to synthesize pure-phase β-Mo 2 C bulk ceramics. The sound velocity-elasticity behavior, thermodynamic properties, and mechanical behavior of the synthesized β-Mo 2 C ceramics were systematically investigated by in-situ high-pressure ultrasonic interferometry and theoretical calculations. The compressive and shear wave velocities, isothermal bulk modulus, shear modulus, Vickers hardness, fracture toughness, Debye temperature, and melting temperature of polycrystalline β-Mo 2 C exhibited a monotonic increase with increasing pressure. The experimental and calculation results showed that β-Mo 2 C had strong ductile behavior and was a ductile ceramic. Additionally, the temperature-hardness relationship of the as-synthesized polycrystalline β-Mo 2 C was investigated by in-situ high-temperature Vickers indentation measurements. The hardness of β-Mo 2 C gradually decreased with increasing temperature, and this ceramic still maintained a hardness as high as 12.3 GPa at 500 °C. These results suggest that the intrinsic mechanical and thermodynamic properties of β-Mo 2 C are dominated by its unique electronic structure and bonding mode. [ABSTRACT FROM AUTHOR]

• Mg-SiC w /Cu composite was fabricated by a combination of stir-casting and ARB processes. • Yield and tensile strengths grew with an increase in rolling passes. • The addition of SiC whiskers and rolling passes resulted in improved microhardness. • SiC whiskers and cu layers as reinforcement enhanced thermal conductivity. In this research, microstructure evaluation, mechanical properties and thermal conductivity of the Mg-SiC w /Cu composite with laminar structure were investigated. For this purpose, SiC whiskers were added to magnesium alloy by using stir-casting, then the Mg-SiC w composite was bonded to copper layers by warm accumulative roll bonding (ARB). Based on the results of optical microscopy (OM) and scanning electron microscopy (SEM), SiC whiskers were well distributed in the magnesium matrix and they were aligned parallelly when the composites were plastically deformed at higher rolling passes. Furthermore, all layers remained continuous with localized necking sites. Also, no intermetallic compounds and phases were detected by XRD and EDS analyzes. Apart from the significant effect of severe plastic deformation on mechanical properties, the findings of mechanical tests point to the usefulness of reinforcements in improving up to 60% microhardness, Young's modulus, yield, and up to 41% tensile strengths. Further, thermal conductivities of composites increased by adding reinforcement and above all by increasing the number of rolling passes. This growth is attributed to the higher thermal diffusivity of copper and whiskers as well as the increased number of conductive layers within composite. [ABSTRACT FROM AUTHOR]

Lignin can be used as a sustainable alternative to bisphenol A (BPA) to prepared lignin-based epoxy resins. Lignin effects including molecular weight, phenolic content, G/S unit ratio and flexible/rigid linkage ratio on epoxy synthesis and performance were summarized comprehensively. The incorporation of lignin with a higher molecular weight would lead to the higher rigidity of epoxy crosslinking network. Higher contents of ether bonds in lignin would provide higher structural flexibility of lignin incorporated epoxy thermosets. Lignin with higher contents of phenolic hydroxyls was more beneficial for improving the reactivity of its epoxy products after glycidylation. Due to the excellent charring capacity of lignin, higher contents of residue char can be produced at higher additions of lignin at high temperatures, while the loss of crosslinking density caused by the increasing lignin addition (especially for the macromolecular lignin) would deteriorate the thermal stability of their thermosets. Several applications of lignin-based epoxy resins were also mentioned based on their mechanical, thermal and chemical properties, such as coatings (with anticorrosion and UV-blocking), adhesives (with highly crosslinking network, excellent mechanical, and thermal properties) and flame retardants (with high charring capability). [Display omitted] [ABSTRACT FROM AUTHOR]

The digestibility of starches with high amylose content can be modulated by the complexation with lipids, which is largely influenced by physical modification methods. In the current work, the impact of ultrasound-microwavre synergistic treatment on the structure and in vitro digestibility of lotus seed starch-glycerin monostearin complexes (LS-GMSc) after retrogradation were investigated. Results showed that 400 W of ultrasound treatment combined with microwave was more conducive to the formation of LS-GMSc, which increased the microcrystalline region and ordering degree of starch. However, excessively high ultrasound intensity weakened V-type diffraction and promoted amylose recrystallization. Investigation of the micromorphology and thermal properties revealed that the existence of V-complexes retarded starch retrogradation, and this effect was significantly enhanced after appropriate ultrasound (400 W) treatment. The digestion showed that 400 W of ultrasound treatment improved the digestive resistance of starch complexes and increased the content of resistant starch. These results are significant to the theoretical foundation and functional application of V-type complexes on anti-gelling and anti-digestion. • 400 W of ultrasound contributed to the formation of LS-GMSc with high complex index. • V-complexes enhanced the growth of microcrystalline region and ordering of starch. • V-complexes retarded the recrystallization of starch after retrogradation. • V-complexes resulted in a reduction of digestibility and the increase of RS content. [ABSTRACT FROM AUTHOR]

The dissolution behaviour of three corn starches, including corn starch (CS), high amylose corn starch (HACS) and waxy corn starch (WCS) with different amylose content in 1-allyl-3-methylimidazolium chloride ([AMIM]Cl) and 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) were studied by comparing their dissolution state in ionic liquids (ILs). Further, the structural and thermal properties of the regenerated starch were analyzed. WCS with the lowest amylose content had the fastest dissolution rate, the most extensive structural damage, and the lowest solubility and required the maximum energy for dissolution. In the process of dissolution-regeneration, the A-type crystalline structure of WCS and CS was completely destroyed and transformed into an amorphous structure, while the B-type crystalline structure of HACS transformed into an ordered V -shaped structure. And the thermal stability of starch was improved after dissolution-regeneration in ILs. Among the two kinds of ILs, [AMIM] Cl had a better ability to dissolve starch, causing minor damage to the starch. [Display omitted] [ABSTRACT FROM AUTHOR]

Thermal camouflage is one of the most effective ways to guarantee the security and survival of military objects against infrared (IR) detectors. However, with the rapid development of IR detection technology, the IR thermal camouflage of objects and weapons has become more and more difficult, and advanced thermal camouflage materials are urgently needed to meet the demands of warfare. So far, two dimensional (2D) nanomaterials have demonstrated excellent performances with low IR emissivity, optoelectronic tunability, and compatible stealth capabilities. Among them, graphene and MXenes are the most attractive 2D materials used for thermal camouflage applications. Here we present a review of recent progress on the thermal camouflage properties of graphene and Ti 3 C 2 T x MXene in the form of composite film, microcapsule and aerogel structures, a summary of current understanding of the working principle of thermal camouflage materials, and current limitations and future opportunities in graphene and Ti 3 C 2 T x MXene research and development. [ABSTRACT FROM AUTHOR]

The major challenge of the current and future miniature compact high-tech electronic devices is thermal management. Micro-scale cooling is one of the promising thermo-fluidic implications possess a great potential in this cutting-edge research area. In this research work, newly emerged MXene (Ti 3 C 2) and functionalized graphene (f-Gr) hybrid nanoflake is implied for the first time in the preparation of Silicon oil (Si-oil) based heat transfer media (MXene:f-Gr/Si-oil hybrid nanofluid) for the micro-scale cooling application. This research concentrates on development, characterization, thermal stability and thermal properties evaluations of new class of hybrid (MXene:f-Gr/Si-oil) nanofluids of three different concentrations of MXene and f-Gr hybrid nanoflakes. The thermal conductivity of the as produced MXene:f-Gr/Si-oil hybrid nanofluids is measured (up to 250 °C) by a Transient Hot Bridge (THB) 500 (Linseis, Germany, current 5 mA, heater-power 18 mW) with Hot Point Sensor (HPS). The measurement is conducted in a newly customized designed industrial grade hotplate heat loss protection chamber with a PID controller. Viscosity is evaluated by a Rheometer with varying temperature of 25 °C from 25 to 125 °C. Optical absorbance is measure using PerkinElmer Lambda 750. The optimum thermal conductivity enhancement is acquired about ∼68% for the MXene and f-Gr hybrid nanoflakes concentration of 0.02 wt% over the pure Si-oil base fluid at 200 °C. The viscosity of MXene:f-Gr/Si-oil hybrid nanofluids is revealed to be autonomous of adding the MXene and f-Gr hybrid nanoflakes into the Si-oil base fluid. However, viscosity of hybrid nanofluid samples is decreased by ∼36% within the increase of temperature from 25 to 50 °C. MXene:f-Gr/Si-oil hybrid nanofluid sample of concentration 0.02 wt% shows the thermal stability up to ∼393 °C (∼14% enhancement over the Si-oil). This significant improvement is advantageous for the cooling of future high-tech electronic systems. This subsequently increases thermal energy acquisition which is valuable for various other applications. [Display omitted] • Synthesizing a unique MXene and f-Gr hybrid composition. • Novel formulation MXene:f-Gr/Si-oil hybrid nanofluids with improved heat transfer attributes. • High temperature thermal conductivity enhancement of new nanofluids using a heat-trap chamber. • Enhanced thermal conductivity of the new hybrid nanofluids over pure Si-oil. • Improved thermal stability of synthesized hybrid nanofluids. [ABSTRACT FROM AUTHOR]

Thermal protection has always been an important issue in the energy, environment and aerospace fields. Porous ceramics produced by the particle-stabilized foaming method have become a competitive material for thermal protection because of their low density and low thermal conductivity. However, the study of porous ceramics for composite systems using particle-stabilized foaming method was relatively rare. Here, silica-alumina composite porous ceramics were prepared by particle-stabilized foaming method, which was achieved by tailoring the surface charges of silica and alumina through adjustment of the pH. Porous ceramics exhibited porosity as high as 97.49% and thermal conductivity (25 °C) as low as 0.063 W m−1 K−1. The compressive strength of porous ceramics sintered at 1500 °C with a solid content of 30 wt% could reach 0.765 MPa. Based on the light weight and excellent thermal insulation properties, the composite porous ceramic could be used as a potential thermal insulation material in the spacecraft industry. [ABSTRACT FROM AUTHOR]

Dense TaTiP 3 O 12 ceramics were synthesized by the solid-state method and spark plasma sintering (SPS) with 6 wt% V 2 O 5 as a sintering aid, and their phase, microstructure, thermal conductivity, hardness, compressive strength, and expansion property and mechanism were investigated. Results show that the pure phase can be achieved by the two methods. In particular, the sample prepared by SPS possesses a relative density of 97.62% and a porosity of 3.07%, and has better properties than that prepared by the solid-state method. The SPS sample has a thermal conductivity at room temperature of 2.03 w/(m · °C), a Vickers hardness of 4.34 GPa and a compressive strength of 175.98 MPa, which are 0.95, 1.49 and 1.59 times greater than those of the sample prepared by the solid-state method, respectively. In addition, the TaTiP 3 O 12 ceramic prepared by SPS exhibits a linear ultralow negative thermal expansion property with a coefficient of thermal expansion of −0.74 × 10−6 °C −1 (-100–400 °C). The negative thermal expansion in TaTiP 3 O 12 is induced by the coupling effect of [Ta(Ti)O 6 ] octahedron and [PO 4 ] tetrahedron caused by the transverse vibration of bridging oxygen atoms. [ABSTRACT FROM AUTHOR]

We study the thermal transport properties of twisted-layer graphite nanofibers. We show that in the presence of a twisted layer, the phonon thermal conductance of a graphite nanofiber of rectangular cross-section varies remarkably with the twist angle and can reach minimum values either at two critical angles θ 1 and θ 2 that conform to the rule θ 1 + θ 2 = 180 0 or exactly at the angle θ = 900. A reduction of roughly 50% of the phonon thermal conductance can be achieved in some structures. We unveil that the twisting effect mainly influences the optical modes, more precisely, the breathing modes ZOꞌ, and leaving almost unaltered the acoustic ones. The effect is also visible in the higher and more numerous van Hove singularities of the phonon density of states. We also point out that the behavior of the thermal conductance with the twist angle is associated with and dominated by the alteration in the overlap area between the twisted and non-twisted layers. The finite-size effect is demonstrated to play an essential role in defining the critical angles at the local minima, where these angles are dependent on the size of the investigated nanofibers, in particular on the proportion between the widths of zigzag and armchair edges. We also analyze the behavior of circular nanofibers where the correlation between the overlap area and the thermal conductance is much smaller. [Display omitted] [ABSTRACT FROM AUTHOR]

As an important potential first wall material in fusion reactor, tungsten will be irradiated by 14.1 MeV fusion neutron and then transmutated to rhenium, osmium, and tantalum during service. Due to rhenium is the main of transmutation products, which will affect the mechanical and thermal properties of the tungsten matrix. Based on this, in this work, the Young's Modulus and thermal properties of W-Re alloys with different rhenium contents were calculated by using the first principle calculations. Then, the uniaxial tensile processes in [1 0 0], [1 1 0], [1 1 1] and [2 1 1] directions were simulated by molecular dynamic simulation method. The results show that the tensile strength of W-Re alloy decreases gradually with the increase of rhenium content. With the increase of the rhenium content, the heat capacity of the material will decrease, and the thermal expansion coefficient increases. [ABSTRACT FROM AUTHOR]

The bluff body is commonly used to improve micro combustion. The micro combustor with multiple rectangular bluff bodies in a single row was proposed. The effects of bluff bodies on H 2 /air combustion characteristics were numerically studied. The temperature distributions, ignition position, combustion efficiency and blow-out limit were investigated via changing the total width and number of bluff bodies. The results show that the combined use of multiple bluff bodies can further expand the blow-out limit of H 2 /Air. The effect of high temperature and viscous force on the flow velocity is main factors for the flame morphology. When the total width of bluff bodies is 2 mm, the blow-out limit decreases with the increase of bluff body number. When the total width of bluff bodies is 4 mm and 6 mm, the blow-out limit increases with the increase of the number of bluff bodies. With the increase of inlet velocity, the complete combustion efficiency decreases. The combustion efficiency in the combustor with wider blow-out limit decreases more slowly. It indicates that the combustor with multi-bluff bodies is more suitable for the operation conditions with high flow velocity. • The effects of multiple bluff bodies on H 2 /air micro combustion characteristics. • Viscous resistance and flow velocity are dominant on flame morphology. • Effect of bluff body's number on blow-out limit at different width is different. • Combustor with wider blow-out limit has higher combustion efficiency. [ABSTRACT FROM AUTHOR]

Good fracture toughness can prolong the service life of thermal barrier coatings under thermomechanical loading. Yttria-stabilised zirconia (YSZ) and other novel thermal barrier coatings have low fracture toughness and are thus prone to spalling failure. High-entropy ceramics can provide coatings with excellent mechanical properties. In this study, (ZrYTaErTi)O composites were prepared via a solid-state reaction method based on the concept of high-entropy ceramics. The high-temperature phase stability and mechanical properties of the material were characterised and analysed by X-ray diffraction (XRD) and microindentation tests. The results showed that (Zr 0.544 Y 0.114 Ta 0.114 Er 0.114 Ti 0.114)O had the best fracture toughness, which is 1.5 times higher than that of YSZ, of the ceramics prepared with different composition ratios. At the same time, the effects of grain size and the introduction of a second phase on the fracture toughness of the composites were analysed. This study provides guidance for future research on improving the mechanical properties of novel thermal barrier coating materials. [ABSTRACT FROM AUTHOR]

A novel B–Si–Zr hybridized ceramicizable resin(BSZ-PR) was fabricated by chemical reaction of boric acid, zirconium hydroxyl-containing polyhedral oligomeric silsesquioxane(Zr-POSS) and phenolic. The incorporation of boric acid and Zr-POSS improved the thermal stability of the resin effectively, and the residual carbon rate increased to 72.63% at 800 °C under nitrogen atmosphere. The flexural strength of carbon fiber/BSZ-PR and high silica fiber/BSZ-PR composites were increased by 25.7% and 175.5%, and linear ablation rates were reduced by 37% and 44.75%, respectively. It was discovered that the ceramic structures such as SiO 2 , ZrO 2 and SiC can be formed at high temperatures as well as under extreme ablative conditions from both BSZ-PR and its fiber-reinforced composites, which may be the key to the improved thermal, ablative properties. [ABSTRACT FROM AUTHOR]

Recently, thermal manipulation in carbon materials has drawn much interest in multiple domains. Compared with existing conductive heating techniques, microwave heating has many advantages such as non-contact heating, fast and accurate temperature response, low energy consumption, etc. However, it is still challenging to realize real-time on-demand thermal manipulation in carbon materials with microwaves, due to the lack of effective control methods on electromagnetic (EM) properties. Here, for the first time, we report a solution to this problem by employing tunable EM resonators. Specifically, EM resonators with electrically tunable lumped elements were designed to couple microwave energy into the carbon material, realizing a pixel-controlled microwave heating performance. Through carefully designing the structure of the EM resonators, the local energy concentration on the tunable lumped elements was remarkably alleviated. Experimental results indicated that the microwave absorbance can be tuned from 12.1% to 99.6%, leading to a tunable heating rate ranging from 1.3 °C/min to 13.5 °C/min under fixed microwave power of 600 W. Moreover, a pixelated thermal manipulation was demonstrated through a thermal display of Arabic numerals. Our work may open new avenues for thermal manipulation in carbon materials and can be applied to complex thermal tasks such as customized materials processing, thermal display, deicing and defrosting, etc. [Display omitted] • Electromagnetic resonators with pixel-controlled tunable microwave absorbance were designed. • The local energy concentration on the tunable lumped elements was remarkably alleviated. • The robustness of the designed resonators against polarization and incident angles was validated. • A time-space dynamical heating performance was demonstrated, and a thermal display of Arabic numerals was exhibited. [ABSTRACT FROM AUTHOR]

It is an established paradigm in the emerging fields of nanoscience, nanotechnology and molecular engineering that a very important domain of fundamental research is associated with carbon-based materials. Ever since the discovery of the first member of the fullerene family (C 60) in 1985, and the subsequent discovery of the other members, fullerenes as a nanoscopic allotrope of carbon with anticipated extensive applications in all areas of nanoscience and nanotechnology (both industrial and medical), materials science and engineering, condensed matter physics and chemistry have occupied a central position in research activities across the globe. Detailed investigations, both experimental and theoretical/computational, into their morphology, mechanical, thermal, chemical, biological, electronic, optical and structural properties have led to the emergence of a well-established and independent science of fullerenes, providing very valuable information both in basic and applied sciences. A comprehensive review of these properties of fullerenes, particularly their applications in the above fields will provide valuable up-to-date and essential background information for engaging in new research in this field and also be able to develop new concepts and applications of these exotic carbon structures. For instance, a recent development is their applications in the emerging field of nanoneuroscience, a field interfacing nanoscience and neuroscience. In this extensive, albeit selective survey, related mainly to the C 60 fullerenes, the processes involving their experimental synthesis, theoretical formulation of their geometrical structures, their mechanical and thermal properties and nanomedical applications have been reviewed and summarized both within the experimental and theoretical/computational domains. Essential theoretical concepts, ranging from discrete atomistic molecular dynamics and molecular mechanics methods to continuum-based methods have been expounded in order to facilitate the pursuance of the reviewed literature and also to aid in the development of further research in this field. [ABSTRACT FROM AUTHOR]

Natural rubber is the only biosynthesized rubber and the most prominent of all the elastomers. Insertion of nanofillers into natural rubber matrix has received much research interest because of the enhanced mechanical, thermal, electrical, antibacterial, etc. properties of the final natural rubber nanocomposite. Molybdenum disulfide (MoS 2), an important member in transition metal dichalcogenides (TMD) is having excellent optical, thermal, mechanical, electronic and antibacterial properties. The inherent properties of this novel filler was exploited through the preparation of natural rubber-MoS 2 nanocomposites via latex dipping method in which tannic acid (TA), naturally occurring macromolecule was used as an exfoliating agent for MoS 2. MoS 2 :TA dispersions were prepared in 1:2, 1:4 and 1:6 ratios by mechanical stirring followed by sonication method for analyzing the optimum amount of exfoliating agent for the preparation of NR-MoS 2 nanocomposite. MoS 2 :TA in 1:4 ratio was found to be the optimum loading for the NR nanocomposite preparation with improved mechanical, thermal and antibacterial properties. The enhanced properties of the NR composites could be attributed to the synergistic effect of both MoS 2 and TA. The current study shows the role of TA in tuning the properties of NR/MoS 2 nanocomposites that enable their potential utilization in various biomedical applications. [ABSTRACT FROM AUTHOR]

• The photothermal conversion performance of Gd 0.7 Nd 0.3 BaCo 2 O 5+δ was better than that of Silicon Carbide which was commercial solar thermal conversion material. • Gd 0.7 Nd 0.3 BaCo 2 O 5+δ had low infrared radiation heat loss at high temperature. • Gd 0.7 Nd 0.3 BaCo 2 O 5+δ exhibited excellent thermal stability at 800 ℃ in air. The efficiency of the concentrated solar power (CSP) framework is significantly influenced by the operating temperature. The solar thermal conversion material with high efficiency and good stability at high temperature in air environment is of importance to obtain the high operating temperature. Here, the optical properties and thermal stability of Gd 1-x Nd x BaCo 2 O 5+δ (0 ≤ x ≤ 0.4, GNBCOx) ceramics were studied to assess their possibility to be applied as high temperature solar absorbers. Results presented that GNBCOx exhibited high absorptance in the solar spectrum and minimal radiation heat loss at infrared wavelengths. In addition, the GNBCOx ceramics demonstrated excellent stability at 800 ℃ in air, indicating that the GNBCOx ceramics could be applied as solar thermal conversion material for upcoming concentrated solar power systems. [ABSTRACT FROM AUTHOR]

Mixed nickel pyrochlore of the Bi 2 NiTaNbO 9 composition (sp. gr. Fd-3m:2 , a = 10.53242(3) Å, Z = 8) in which half of the tantalum(V) ions are replaced with Nb(V) was synthesized by solid-phase reaction for the first time. X-ray diffraction (XRD) data indicate the formation of a disordered pyrochlore structure with nickel, tantalum and niobium ions distributed in the same system of crystallographic positions. Doping with Nb(V) ions affects the microstructure of the sample. A dense, low-porous ceramic with fuzzy grain boundaries is formed. High-temperature XRD study shows that Bi 2 NiTaNbO 9 is thermally stable up to 1050 °C. The thermal expansion coefficient increases uniformly and weakly from 3.3 to 8.6 × 10−6 °C−1 in the interval 30–960 °C, and its average value is 6.0 × 10−6 °C−1. Bi 2 NiTaNbO 9 pyrochlore can be classified as a weakly expanding compound with isotropic thermal expansion. Doping with niobium had no significant effect on its thermal behavior and stability. By impedance spectroscopy the electrical properties of the samples are investigated. It was found that Bi 2 NiTaNbO 9 exhibits dielectric properties. At room temperature and 1 MHz the sample exhibits dielectric permittivity with the value equals to 40–41 (dielectric loss tangent is 0.01). The sample capacitance weakly depends on temperature and frequency. The conduction activation energy is 1.34 eV. Doping with Nb(V) ions improves the sample dielectric characteristics. [ABSTRACT FROM AUTHOR]

Strontium and Yttrium-doped and co-doped BaTiO 3 (BT) ceramics with the stoichiometric formulas BaTiO 3 , B 1-x Sr x TiO 3 , Ba 1-x Y x TiO 3 , BaTi 1-x Y x O 3 , Ba 1-x Y x Ti 1-x Y x O 3 , and Ba 1-x Sr x Ti 1-x Y x O 3 (x = 0.075) noted as BT, BSrT, BYT, BTY, BYTY, and BSrTY have been synthesized through sol-gel method. X-ray diffraction (XRD) patterns of the prepared ceramics, calcined at a slightly low temperature (950 °C/3h), displayed that BT, BSrT, and BYT ceramics possess tetragonal structures and BTY, BYTY, and BSrTY have a cubic structure. The incorporation of the Ba and/or Ti sites by Sr2+ and Y3+ ions in the lattice of BaTiO 3 ceramic and the behaviors of the crystalline characteristics in terms of the Y and Sr dopant were described in detail. The scanning electron microscopy (SEM) images demonstrated that the densification and grain size were strongly related to Sr and Y elements. UV–visible spectroscopy was used to study the optical behavior of the as-prepared ceramic samples and revealed that Sr and Y dopants reduce the optical band gap energy to 2.74 eV for the BSrTY compound. The outcomes also demonstrated that the levels of Urbach energy are indicative of the created disorder following the inclusion of Yttrium. The measurements of the thermal conductivity indicated the influence of the doping mechanism on the thermal conductivity results of the synthesized samples. Indeed, the thermal conductivity of BaTiO 3 is decreased with Sr and Y dopants and found to be in the range of 085–2.23 W.m-1. K−1 at room temperature and decreases slightly with increasing temperature from 2.02 to 0.73-W.m-1. K−1. Moreover, the microstructure and grains distribution of the BT, BSrT, BYT, BTY, BYTY, and BSrTY samples impacted the compressive strength, hence; the compressive strength was minimized as the grain size decreased. [ABSTRACT FROM AUTHOR]

In this work, we propose a pre-consolidated form of single-walled carbon nanotubes (SWCNT) – SWCNT briquettes – as a binder-free, robust, and safe material for manufacturing electrically and thermally conductive thermoset nanocomposites with universal applicability to all polymer matrices. We prove that the briquettes provide similar performance in nanocomposites compared to reference samples: a pristine powder, a commercial masterbatch and an aerogel based on the same type of SWCNTs. Using comprehensive sets of methods, we observe no significant differences in electrical (∼10−7-1 S/cm depending on SWCNT loading) and thermal (0.210–0.304 W/mK) conductivities for all sample types across a wide range of SWCNT concentrations. Moreover, the percolation thresholds of nanocomposites for SWCNT briquettes were ultra-low and close to that of pre-dispersed masterbatches (0.001–0.003 wt%). Pre-consolidated SWCNT powder is shown to provide the same final functional properties, while being free from common nanotube drawbacks such as the higher price of masterbatch manufacturing or aerosolization and low dispersibility during handling for the SWCNT powder/aerogel. The briquettes not only offer a safe solution for large scale fabrication, cutting away the need for personal and facility level safety measures, but do so at no significant cost increase, can be used with any polymer matrix and associated industrial processing route without any loss of final properties. This makes them universally attractive for all composite industrial production as well as small scale low capital laboratories. [Display omitted] • Carbon nanotube briquettes are proposed as an additive for polymer nanocomposites. • Briquettes show similar performance to powder and masterbatches. • Briquettes are binder-free, robust, safe, non-aerosolizing and cost-effective. • Nanocomposites were studied for electrical and thermal functional properties. • These nanotubes have advantages over pristine, expanded powder and masterbatches. [ABSTRACT FROM AUTHOR]

Agglomeration of carbon nanotubes (CNTs) is a key phenomenon that affects the effective thermal conductivity of CNT-polymer nanocomposites. This issue needs to be adequately studied especially in the practice of prediction of the effective thermal properties of CNT nanocomposites. In this study, we developed a multiscale model within the framework of effective medium theory to predict the effect of CNT agglomeration on the overall thermal conductivity of the hierarchical CNT-polymer nanocomposite system over a wide range of CNT loading. With an introduced Cauchy cumulative probability function, we developed a new model of CNT agglomeration wherein the CNT volume fraction progressively evolves with the total loading of the CNT fillers in the composite. This model is self-consistent and it leads to a very good agreement with experimental observations. The entire multiscale approach consists of the newly developed model of the progressive agglomeration as well as models that altogether take into account the effect of two types of CNT interfacial thermal resistance and the unique feature of the CNT nanostructure. We highlighted this multiscale approach with its implementation in the prediction of the overall thermal conductivity. Good agreement was confirmed between the prediction and the experimental data. The study shows that the existence of CNT agglomerates downgrades the thermal percolation networks and it can cause a decrease up to 50% in the overall thermal conductivity of the nanocomposite. Two important parameters for the progressive agglomeration model were identified and their influences to the predicted results were examined. [Display omitted] [ABSTRACT FROM AUTHOR]

Significant research interest has been directed towards the deployment of direct air capture (DAC) as a net-negative CO 2 emissions technology to help limit global temperature rise to below 2 °C. The scope of this review is to outline the advancement of adsorption-based DAC technologies, as well as to highlight the still-existing data gaps, for both materials' development and process design in the period 2016 – 2021. On the material side, we highlight the available and missing data on adsorbent properties in relation to what is needed for process modelling and design. We cover material densities, textural properties, thermal properties, adsorption isotherms (i.e. CO 2 , N 2 , O 2 , H 2 O), adsorption kinetics, and adsorbent stability towards humidity, oxidation, and cycling. On the process side, we provide a detailed look at key process studies conducted in the same time frame by considering the trade-offs to be expected in the design of the adsorption-based DAC process. We focus on process configuration and contactor design, desorption processes, and the need for systematic reporting of key performance indicators to allow for accurate comparisons and benchmarking. Throughout the review, we identify the lack of synergy between material and process development which must be addressed to advance the field of DAC by adsorption. • Review of adsorption-based DAC technologies developed in the period 2016 – 2021. • Analysis of existing data gaps in DAC materials development and process design. • Tabulation of material and adsorption properties for over 200 DAC adsorbents. • Overview of contactor designs, process configurations and key performance indicators. • Increased synergy between materials and process development required to advance DAC. [ABSTRACT FROM AUTHOR]

Timoho fiber (TF) is a biodegradable bio-fiber rich in cellulose and a renewable agro textile fiber rich in cellulose polysaccharides. Isolation of micro cellulose from TF is an alternative reinforcement approach in a bio-composite application. This study characterized TF obtained from isolation employing FTIR, XRD, SEM-EDS, and TGA using hydrolysis. Pretreatment was done using alkaline, bleaching, and hydrolysis. FTIR confirmed that the maximum amount of noncellulosic materials had been removed from TF. The XRD result showed that hydrolysis treatment increased the crystal size and crystallinity index of the TF (88.68 %). TGA also revealed that the highest thermal stability had been found in the hydrolyzed TF. The micro cellulose TF represented an interesting source of cellulose reinforcing materials, and it might be continued in the form of nano cellulose. [ABSTRACT FROM AUTHOR]

The aim of this study was to better understand the underlying drug release characteristics from Gg-cl-poly(NIPA- co -AA)/CoFe2O4 hydrogel containing metformin hydrochloride as model drug. Nanocomposite's hydrogel of gum ghatti free radical polymerization is used for the controlled release of metformin hydrogen chloride. Gum ghatti and CoFe2O4 nanoparticle dispersion were grafted by acrylic acid and N-isopropylacrylamide, employing graft copolymerization in the presence of N, N′–methylene-bis-acrylamide (MBA) as cross linker, and ammonium persulfate (APS) as initiator. The synthesized nanocomposites hydrogel was characterized using FTIR, SEM, TGA and DSC. Drugs were all released through diffusion in the hydrated matrix and polymer relaxation, irrespective of the drug solubility. In vitro drug release studies, at different pH values of pH = 4.0, 7.4 and 9.2 was employed. Drug release was influenced by the change of pH. The pH of 7.4 was considered as the optimized pH for maximum drug release. The nanocomposites hydrogel was loaded with metformin hydrochloride drug (100 mg) which is an antidiabetic drug to investigate the release profiles in PBS (pH 7.4). The effects of polymer level and initial drug loading on release depended on drug properties. Different models were studied for release kinetic studies which showed that the zero-order model suggested the best kinetics release studies in PBS (pH- 7.4) and showed sustained release. The kinetics of drug release were discovered to fit the Korsmeyer-Peppas model with n > 1, indicating a specific case II transport mechanism. [ABSTRACT FROM AUTHOR]

Starch in native form has limited application due to functional and physicochemical characteristics. To overcome these limitations, starch can be modified by non-thermal technologies such as high hydrostatic pressure (HHP). This study investigates high-pressure-induced gelatinization and the effect of this process on the structural, functional, morphological, pasting, thermal, physical and rheological properties of millet starch. The suspension of millet starch and water was pressurized at 200, 400 and 600 MPa for 10, 20 and 30 min to modify the starch in terms of structure, morphology, some physicochemical and rheological properties. Swelling strength and starch solubility decreased as a result of treatment with HHP. All treatments caused to increase in water holding capacity of the starch (from 0.66 % for native starch to 2.19 % for 600 MPa-30 min). Thermal analysis showed a decrease in gelatinization temperature and enthalpy of gelatinization and the pasting properties showed a decrease in the peak viscosity after HHP treatment. In addition, HHP treatment caused to increase in the hydration ability of starch by creating porosity and gaps in the granule surface and increasing the specific surface area. HHP application resulted in an increase in the peak time and pasting temperature and a decrease in breakdown and peak viscosities, final viscosity and setback viscosity in comparison with native starch of millet. The starch sample treated with 600 MPa for 30 min had the lowest syneresis and retrogradation ability. Increasing pressure and the time led to an increase in the elastic nature of the starch samples. According to the results, it is possible to increase usage area of starches in the food industry by improving its technological with HHP. This green physical technology can influence the quality parameters of starch, which can provide benefits for product machining and economic purposes. • Gel prepared with starch treated with HHP had higher resistance to applied force. • HHP-treated starch samples had lower gelatinization temperature • Gels with lower viscosity values were obtained by application of HHP. • HHP caused to increase in water holding capacity of starch. • Some technological problems of starch can be eliminated by HHP application. [ABSTRACT FROM AUTHOR]

Mn doping and S-evaporation are strategies used to improve the thermoelectric properties and thermal stability of cuprous sulfide thermoelectric materials. Cu 1.8 S and Mn-alloyed Cu 1.8 S powders were prepared via ball milling, and different samples were obtained via current-assisted sintering at different times. It was found that Mn and S-evaporation optimized the carrier concentration and thus improved the figure of merit (ZT) of the samples. The introduction of pore defects induced by S-evaporation also improved the ZT. The maximum ZT of the optimized sample reached 0.89 at 500 °C. Mn in the samples reacted with oxygen to form an oxide film on the surface of the block, which inhibited the kinetic process of Cu 1.8 S decomposition and improved the thermal stability of the samples. However, the reaction between Mn and oxygen led to a continuous loss of metal cations in the material, resulting in changes in the thermoelectric properties. [ABSTRACT FROM AUTHOR]

In this study, La 1- x Nd x MgAl 11- x Sc x O 19 (x = 0.1, 0.2, 0.3; abbreviated as LNMAS-1, 2, 3) coatings which are supposed to possess better properties than LaMgAl 11 O 19 (LMA) were plasma-sprayed and their high-temperature performance were comparatively investigated. Results show that addition of Nd3+ and Sc3+ as dopants to LMA endows corresponding coatings with reduced thermal conductivity and enhanced thermal expansion coefficient, while maintaining advantageous phase stability, although still being subjected to amorphization in plasma flame and following crystallization upon high-temperature service. Furthermore, the doping could cause adherence increasing between topcoat/bondcoat, benefiting from improved melting condition, especially in LNMAS-2 and LNMAS-3 coatings, which is related to the specific powder morphology and lowered melting point. During exposure to 1350°C, mechanical performance and structure integrity of doped free-standing LNMAS coatings can be well preserved even after 400 h aging. In thermal cyclic fatigue test, LNMAS-2 and LNMAS-3 coatings undertake thermal cycling lifetime of ∼181 and 191 cycles at 1100°C, respectively, 40% durable than that of LMA coating. These preliminary results suggest that LNMAS-2, 3 might be promising candidates for advanced thermal barrier coating applications. [ABSTRACT FROM AUTHOR]

The high-entropy ceramic materials (Zr 0.25 Ce 0.25 Hf 0.25 Y 0.25)O 1.875 (H-0) and (Zr 0.2 Ce 0.2 Hf 0.2 Y 0.2 RE 0.2)O 1.8 (H-RE) (RE = La, Nd and Sm) with fluorite structure and homogeneous element distribution were prepared. With fluorite structure, fine grain size and high density, the H-0 and H-RE ceramics displayed low thermal conductivity, suitable thermal expansion coefficient, high hardness and fracture toughness. The effect of La, Nd and Sm on the mechanical, heat conductivity and heat expansion properties of high entropy ceramics were discussed. The single-phase high-entropy ceramic materials in this work are very suitable for application as thermal barrier materials. [ABSTRACT FROM AUTHOR]

Microwave radiation (MW) is an environment-friendly technology used to physically modify flours. Rice flour was MW-treated at different moisture content (MC) (3 %, 8 %, 13 %, 15 %, 20 % and 30 %). In vitro starch digestibility was determined and related to the changes caused by MW treatment to flours' structure and thermal properties, which were influenced by MC. A reduction of 49 % and 65 % in the gelatinization enthalpy of samples treated at 20 % and 30 % MC denoted a partial gelatinization. A loss of granular crystallinity in treated samples was confirmed by XR-diffraction and FTIR, particularly at 15 %, 20 % and 30 % MC. MW promoted the formation of random-coil, α-helix and β-turn protein structure, and the disappearance of LF-β-sheet. Morphological differences were found between samples treated at 8 % MC (loss of polygonal structure, protein layer covering granules' surface and small holes) and 30 % MC (rounded and aggregated granules, covered with exudate amylose). In vitro starch digestibility revealed that samples treated at 20 % and 30 % MC showed 40 % and 47 % higher rapidly digestible starch, 48 % and 70 % lower slowly digestible starch and 90 % lower resistant starch than the untreated flour. Flour MC in MW-treatment allowed the modulation of structural and thermal characteristics of rice flour and consequently its starch hydrolysis rate. • Microwave treatment (MWT) modified the intensity of rice flour X-ray diffractograms. • Signs of partial gelatinization were found in samples treated at 20 and 30 % humidity. • The MWT decreased the 1047:1022 ratio in FTIR spectra regardless the flour humidity. • The MWT promoted the formation of random coil, α-helix and β-turn protein structure. • The flour humidity during the MWT determined the rate of starch hydrolysis. [ABSTRACT FROM AUTHOR]

• Composting rates of polyesters differ strongly depending on the individual studies. • Comparison of composting results and times of polyesters is difficult as no standard conditions are used. • There is no particular standard protocol that give the best composting assessment for polyesters. • This article summarises composting data of representative polyesters using different testing protocol. The aerobic composting of biodegradable plastics can be a promising solution to the growing issue of waste accumulation. Therefore, this article offers a review of papers investigating the biodegradability of polyesters (PLA, PHB, PBS and PCL) in home- and industrial composting. Not only the thermal and biodegradation properties are discussed, but also a comparison is made between the different polyesters under the same composting conditions. From this review, it becomes clear that composting shows promise for polyester waste management. However, although several methods for assessing the composting properties of polyester have been developed, the fact that they rarely follow the same standards does not allow for a comparative analysis that would clearly define composting as the most viable solution. [ABSTRACT FROM AUTHOR]

(Ho 1/4 Er 1/4 Yb 1/4 Lu 1/4) 2 SiO 5 is synthesized and characterized for the application of a promising multifunctional thermal and environmental barrier coating (TEBC) material. X-ray diffraction and scanning electron microscopy analysis indicate that a X2-type multiple-RE silicate (4RE 1/4) 2 SiO 5 is formed with homogeneous distribution of the four rare earth species. Dense bulk sample exhibits excellent phase stability up to 1400 °C. Key properties including Young's modulus, thermal conductivity and thermal expansion coefficient show interesting composition effects. Specially, (Ho 1/4 Er 1/4 Yb 1/4 Lu 1/4) 2 SiO 5 demonstrates higher elastic stiffness, lower thermal conductivity, lower thermal expansion coefficient and good resistances to molten CMAS and water vapor corrosions. These results confirm the strategy of multiple-RE engineering that may provide optimal property of advanced TEBCs. [ABSTRACT FROM AUTHOR]

It was investigated that the rheology, starch-gluten-surimi network, thermal properties, and water distribution of surimi-wheat dough, and texture characteristics, cooking properties, and microscopic characteristics of the surimi-wheat noodles with konjac glucomannan (KGM) of different viscosities in different concentrations. The results showed that the storage (G′), loss (G″), and complex (G⁎) moduli of dough increased with adding KGM. With the increase of KGM viscosity, the reduction in the free sulfhydryl (SH) content to 0.84 μmol/g and the increase in the free water content to 8.25 % led to significantly improved enthalpy and the microstructure density. The hardness and tensile length of noodles were substantially increased by adding 3 % KGM. In addition, the KGM enhanced the starch-gluten-surimi network and improved the cooking qualities and textural properties of noodles. More importantly, the application of KGM in the wheat flour composite system also showed better performance. Thus, the introduction of KGM into the surimi-wheat dough had a significant effect on the optimization of the macro- and micro-characteristics of dough and noodles. [ABSTRACT FROM AUTHOR]

The challenge of dispersing nanocellulose in hydrophobic polymers such as polylactic acid (PLA) still obstacles the further application of cellulose nanocomposites. An environment-friendly and facile wet-shearing pretreatment strategy without using any organic solvent was developed in this work. Silane modified lignocellulose nanofiber (SLCNF) was pre-dispersed into PLA by wet-shearing pretreatment, followed by extrusion process and the SLCNF could be dispersed extremely well in PLA matrices. SLCNF formed a crosslinked network and had an improved compatibility, which improved the mechanical and thermal properties of PLA composites. The tensile strength, elongation at break and thermal deformation temperature of the composites were increased by 12.6 %, 32.4 % and 9.1 °C, respectively. Moreover, SLCNF promoted the crystallization of PLA as a heterogeneous nucleating agent and the crystallinity was increased by about 40 %. This study provides an effective way to disperse nanocellulose in polymer matrix with high efficiency to enhance polymer-based composites. • Wet-shearing pretreatment combined with oven drying is an effective method for dispersing nanocellulose in polymer matrix. • Silane modified reed straw nanofibers formed a cross-linked network and have an improved compatibility with PLA matrix. • Enhanced mechanical, thermal and crystallization properties of polylactic acid/reed straw nanofiber blends [ABSTRACT FROM AUTHOR]