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Fiber-reinforced polymers are crucial for insulating electrical equipment, necessitating accurate thermal property data for an effective thermal analysis. This case study uses a cost-effective method to thermally characterize a glass fiber-reinforced epoxy resin used in air-core reactor insulation. The approach simultaneously estimates temperature-dependent thermal conductivity (k) and specific heat (cp) for class H/180 insulation. By analyzing transient heat conduction in a 3D composite sample under vacuum and at various temperatures, the method optimizes sensor placement, enabling accurate property estimation with a single thermocouple. The estimated through-thickness thermal conductivity at room temperature deviates by less than 6% from standard guarded hot plate measurements. The method's reliability is confirmed by accurately retrieving the applied heat flux using the estimated properties and measured temperature data. The results are valuable for designing accurate simulation models to predict and manage the thermal behavior of air-core reactors, as implemented by GE Grid Solutions in Itajubá, Brazil. [ABSTRACT FROM AUTHOR]

Phase-change materials (PCMs) can be used to develop thermal energy storage systems as they absorb large amount of latent heat nearly at a constant temperature when changing phase from a solid to a liquid. To prevent leakage when in a liquid state, PCM is shape stabilized in a polymer matrix of high-density polyethylene (HDPE). The present research explores the injection-molded mechanical and thermal properties of different PCM/HDPE composite ratios. The tensile strength and modulus of elasticity at room temperature and with the PCM fully melted within the composite are measured. Additionally, the hardness, latent heat of fusion, phase-change temperature, and thermal conductivity are investigated. An analysis of microstructures of the composite is used to support the findings. The PCM within the PCM/HDPE composite gives it the benefit of thermal storage but causes a decrease in mechanical properties. [ABSTRACT FROM AUTHOR]

Bio-based epoxy thermoset resins have been developed from epoxidized soybean oil (ESO) cured with tannic acid (TA). These two substances of vegetable origin have been gathering attention due to their accessibility, favorable economic conditions, and convenient chemical functionalization. TA's suitable high phenolic functionalization has been used to crosslink ESO by adjusting the −OH (from TA):epoxy (from ESO) molar ratio from 0.5:1 to 2.5:1. By means of Fourier-transform infrared spectroscopy, resulting in thermosets that evidenced optimal curing properties under moderate conditions (150–160 °C). The thermogravimetric analysis of the cured resins showed thermal stability up to 261 °C, with modulable mechanical and thermal properties determined by differential scanning calorimetry, dynamical mechanical thermal analysis, and tensile testing. Water contact angle measurements (83–87°) and water absorption tests (0.6–4.5 initial weight% intake) were performed to assess the suitability of the resins as waterproof coatings. Electrochemical impedance spectroscopy measurements were performed to characterize the anti-corrosive capability of these coatings on carbon steel substrates. Excellent barrier properties have been demonstrated due to the high electrical isolation and water impermeability of these oil-based coatings, without signs of deterioration over 6 months of immersion in a 3.5 wt.% NaCl solution. These results demonstrate the suitability of the developed materials as anti-corrosion coatings for specific applications. [ABSTRACT FROM AUTHOR]

The characterization of the thermal properties of polymers represents a fundamental step in improving materials for energy harvesting processes. Thermal conductivity, for example, is measured by measuring heat flux and temperature difference. This study seeks to design and fabricate an experimental set‐up to measure the thermal conductivity of low‐thickness polymers at room temperature. It is unique in that it is an affordable and lightweight instrument developed using electrical resistance as a heater and a limited number of components. Error analysis and reproducibility analysis were carried out for the thermal conductivity. The instrument was found to be reliable in making thermal conductivity measurements with an average of ±7%. [ABSTRACT FROM AUTHOR]

This study investigated the effects of ultrasonic and three chemical individual and dual modification treatments on corn starch's physicochemical, thermal, and rheological properties. Ultrasonication and the three chemical treatments disrupted the starch granules with a decrease in particle size and a significant increase in the ζ-potential. The hydrophilicity of ultrasonic-oxidized dual-modified starch (U-O-CS) was the highest, at 0.854 g/g. The lipophilicity of ultrasonic-esterified dual-modified starch (U- E -CS) was the highest, at 1.485 g/g. The gelatinization temperature of ultrasonic, oxidation, and cross-linking modified starches increased significantly, with cross-linking starches being the largest. Oxidative treatment significantly decreased the starch's G' and G" and weakened the textural properties. The rheological properties of U-O-CS were further weakened. The G' of the starch decreased after the esterification treatment, while the G" increased, and the textural properties were cut. The maximum rheological and textural properties were obtained for crosslinked modification, with a hardness value of 284.70 g. [Display omitted] • Ultrasound has a synergistic effect on the properties of chemically treated starch. • Ultrasonic oxidation dual modified starch has the highest hydrophilicity. • Cross-linking starch has the best thermal stability and rheological properties. [ABSTRACT FROM AUTHOR]

Wood impregnated with a multicomponent mixture of fatty acids as a bio-based phase change material (BPCM) to improve its thermal characteristics was studied. The studied wood/BPCM composites can be used as internal elements in buildings for energy storage. Scots pine and beech sapwood were impregnated with a multicomponent mixture of linoleic acid and coconut oil fatty acids at a ratio of 20:80. Leakage test was conducted and revealed that the maximum leakage for pine and beech were 9 and 8%, respectively. Light microscopy was employed to demonstrate the distribution of the BPCM in the wood structure. Rays in both pine and beech wood served as pathways for impregnation of the BPCM to partly fill the tracheid lumens (pine) and vessels (beech). Thermal characterization of the studied samples employed T-history and DSC methods, concluding that the impregnated wood had significant thermal mass, ability to store excessive energy in terms of latent heat and keep the temperature constant for long time. The specific heat capacity of the impregnated samples was 4–5 J g−1 K−1 i.e., higher than that of the untreated control samples of ca. 2 J g−1 K−1. The thermal conductivity of the samples before and after the impregnation was measured using heat flow meter method and the results showed that the untreated beech wood had higher thermal conductivity compared to pine and the parameter improved when the cell lumens were filled with the BPCM. Scots pine wood with to 80% mass percentage gain (MPG) after impregnation demonstrated an increment in thermal conductivity of 33% while Scots pine and beech with 43 and 38% MPG demonstrated an increase of the conductivity with 8 and 11%, respectively. [ABSTRACT FROM AUTHOR]

Maintenance of adequate thermal properties is critical for correct operation of a gas foil bearing. In this work, the authors present the results of the experimentally conducted thermal characterization of a prototype installation of the bearing. A novel method of temperature identification, based on integrated thermocouples readings, has been employed to determine the thermal properties of the specialized sensing top foil mounted in the tested bearing. Two measurement campaigns have been subsequently completed, applying freely-suspended and two-node support configurations, to gather complementary knowledge regarding the bearing's operation. Apart from the rotational speed and temperature field measurements, the authors have also studied the friction torque and the shaft's journal trajectories based on its radial displacements. The temporal courses for the above-mentioned quantities have enabled inference on the effects present during run-up, run-out and stable state operation at a constant speed. As confirmed, the applied distribution of the integrated sensors allows for temperature readings on the entire outer surface of the foil, and therefore, provides useful data for the bearing characterization. The work is concluded with presentation of the recommended directions regarding future improvements of the proposed measurement technique and more comprehensive study of the bearing's characteristics. [ABSTRACT FROM AUTHOR]

This paper reports on the processing and overall characterization of walnut shell powder (WSP) filled polyester composite. The effects of this filler on the properties of polyester resin are studied by conducting various characterization tests under controlled laboratory conditions. The composite formation mechanism has been explained by the interpretation of Fourier transform infrared (FTIR) spectroscopic and X-ray Diffraction (XRD) analysis. The study reveals that the incorporation of WSP particles modifies the density and porosity of the composites along with their tensile, compressive, flexural, and impact strengths. Thermo-gravimetric analysis (TGA) is done on the samples to get an insight into their thermal stability. Measurement of thermal conductivity is carried out on samples of different compositions, and it is found that the inclusion of walnut shell powder leads to significant improvement in the thermal insulation capability of polyester resin. It is recorded that with an increase in the WSP content from 0 to 20 wt. % in polyester, the value of the effective thermal conductivity (K eff ) drops by about 42%. It is further seen that with the incorporation of WSP, the coefficient of thermal expansion (CTE) of polyester is substantially lowered. [ABSTRACT FROM AUTHOR]

In this research paper, the determination of thermal expansivity and thermal conductivity has been accomplished for Al 6061, Silicon Carbide and Graphite hybrid metal matrix composites from room temperature to 3 0 0 ∘ C. Aluminium-based composites reinforced with Silicon Carbide and Graphite particles have been prepared by stir casting technique. The thermal expansion and thermal conductivity properties of hybrid composites with different percentage compositions of reinforcements have been investigated. The results have indicated that the thermal expansivity and thermal conductivity of the different compositions of hybrid MMCs decrease by the addition of Graphite with Silicon Carbide and Al 6061. Few empirical models have been validated for the evaluation of thermal expansivity and thermal conductivity of hybrid composites. Using the experimental values, namely modulus of elasticity, Poisson ratio and thermal expansivity, computational investigation has been carried out to evaluate the thermal parameters, namely thermal displacement, thermal strain and thermal stress. Similarly, using the experimental values, namely density, thermal conductivity, specific heat capacity and enthalpy at varying temperature ranges, computational investigation has been carried out to evaluate thermal gradient and thermal flux. [ABSTRACT FROM AUTHOR]

In the current research, magnesium oxide nanopowder (n-MgO) was prepared using dry chemistry method. The structural characterization of the prepared n-MgO was carried out using x-ray diffraction (XRD) technique and scanning electron microscope (SEM). The powder was mixed with epoxy resin at ratios of 2%, 4%, 6% and 8%. The effect of reinforcement of n-MgO on thermal properties of epoxy-resin-based composites such as thermal rate and insulation index was studied at three different temperatures: 380, 680 and > 1800 K. Thermal testing that was carried out included thermal conductivity measurement using Mathis TCi and erosion rate test using oxy-acetylene flame technique. The results showed that increasing the content of n-MgO can significantly enhance the thermal properties such thermal conductivity, thermal diffusion, specific heat capacity as well as thermal resistance. [ABSTRACT FROM AUTHOR]

Floating offshore wind turbines (FOWTs) face a major challenge when focusing on the effect of biofouling: biofouling by mussels on bottom-surface mobile connections, such as dynamic submarine electrical cables and mooring lines. Mussels are one of the dominant species in offshore wind farms in North Atlantic area. Amongst other effects, mussels can cause significant thermal impacts on dynamic power cables, which can lead to reduced performance or even failure. To address this issue, it is essential to thermally characterize mussels, including estimating their thermal resistance, so that they can be properly incorporated into the design and maintenance phases of the submarine dynamic power cables. This study investigates three key factors that could affect mussel thermal resistance, including mussel water filtering, imposed power during measurement, porosity (mussel's age). Results reveal that the thermal resistance of living mussels is smaller than that of dead mussels due to the metabolic process of water filtering. Additionally, thermal resistance decreases as mussel age (porosity) and imposed power during measurement increase. The results of this study offer novel insights into the thermal properties of mussels and their impact on submarine dynamic electrical cables used in FOWTs. The findings have practical implications for the design and maintenance of FOWTs, enhancing the sustainability of offshore wind energy production and provide a complete protocol for further investigations. [ABSTRACT FROM AUTHOR]

Different kinds of soot were evaluated as selective coverings for use in solar cookers. The coatings were analyzed by measuring their thermal parameters and reflectance in the range of 280–2400 nm. Analyses include a comparison of black paints with coatings made from different kinds of soot. Coatings were prepared with different particle sizes and applied to a solar cooker to determine standard cooking power, thermal performance and exergetic efficiency. The thermal parameters obtained for the solar cooker after applying the coatings made with different kinds of soot showed no significant differences in relation to particle size or the kind of soot. Findings show that measurements of thermal parameters of the soot-based coatings were 20% higher than the values obtained for commercial black paints. Also, the solar reflectance values of the soot-based coatings averaged 2.5%, while the figure for the commercial black paints was 4.5%. Finally, a semi-empirical model using the measured reflectance was employed to estimate the standardized cooking power, with favorable results in accordance with the experimental data. [ABSTRACT FROM AUTHOR]

The breakdown voltage of GaN/Si high-electron-mobility transistors (HEMTs) for power electronics has shown to be improved by removing the silicon substrate. The drawback to this approach is the increase in the device’s thermal resistance, which limits the power dissipation that the device can achieve before severe degradation. This letter shows the ability to improve the thermal dissipation of these devices by depositing copper (Cu) below aluminum nitride (AlN) filled etched back GaN-on-Si HEMTs. The device’s channel temperature is measured via Raman thermometry. The device’s transient thermal dynamics is investigated via transient thermoreflectance imaging, and the temperature profile across the gate metal is monitored. In addition to the device’s thermal properties, a residual stress analysis of the GaN channel is performed via photoluminescence. A notable decrease in the tensile residual stress is observed with the removal of the substrate and the addition of the AlN and Cu layers. Overall, the backside copper is shown to decrease the gate temperature of the etched backed AlN filled devices while maintaining a high breakdown voltage. [ABSTRACT FROM AUTHOR]

Highlights • Develop a method to measure thermal conductivity of materials with limited size. • Measure the thermal conductivity of reaction chambers of bombardier beetles. • Explain why bombardier beetle can withstand the internal explosive reaction. Abstract Bombardier beetles, as their name implies, defend themselves against the potential predators by spraying boiling-hot and corrosive chemicals which are products of an explosive biochemical reaction taking place in the paired organs called reaction chambers (RCs). Why these beetles can withstand the explosive reaction that takes place in their bodies? Knowledge of thermal properties of the RCs will help to shed light on this puzzle. However, the submillimeter dimension and irregular shape of the RCs discourage the traditional methods for thermal characterization. To overcome this challenge, in this paper a method is developed particularly for measuring the thermal conductivity of a material with dimension as small as submillimeter. The measurement results by this method are demonstrated reliable especially for polymeric or organic materials including the RCs of bombardier beetles. The results in this paper not only help to understand the superior thermal insulation of the RC wall but also offer a facile approach to measuring the thermal conductivity of materials in submillimeter scale. [ABSTRACT FROM AUTHOR]

• The polarized spectra, thermal properties and laser performance of Nd:GdScO 3 crystal were systematically studied in detail. • Nd:GdScO 3 crystal is meaningful for realizing dual-wavelength emissions near 1070–1085 nm, and the maximum emission cross-section is up to 9.405 × 10-20 cm2. • Continuous-wave laser operation at 1.08 µm was realized in Nd:GdScO 3 crystal for the first time, and the maximum output power yields 3.16 W with a slope efficiency of 47.5%. The spectroscopic and thermal properties, and laser performance of Nd:GdScO 3 crystal grown using the Czochralski method were studied in detail. The corresponding XRPD pattern shows that the crystal belongs to the orthorhombic system with the cell parameters of a = 5.487 Å, b = 5.752 Å, and c = 7.940 Å. Polarized absorption and fluorescence spectra were recorded, and the spectroscopic parameters were systematically calculated by the Judd–Ofelt theory. The absorption cross-sections at 806.5 nm are 4.666, 2.479 and 2.354 × 10-20 cm−2 with polarization along the principal a -, b - and c -axis, respectively. The maximum emission cross-section is 9.405 × 10-20 cm2 at 1083.8 nm, and the fluorescence lifetime of 4F 3/2 energy level is found as 147.4 µs. The specific heat of the crystal is 0.382 J g−1 K−1 at 298.15 K, and the principal thermal conductivity components at room temperature are k 1 = 3.24, k 2 = 3.17, and k 3 = 3.11 W m−1 K−1, respectively. Continuous-wave laser operation at 1.08 µm was realized in Nd:GdScO 3 crystal for the first time, and the maximum output power yields 3.16 W with the slope efficiency of 47.5%. [ABSTRACT FROM AUTHOR]

A new multiple heat path dynamic compact model extraction method for LED packages with silicone domes is proposed. The method enables separate characterization of the LEDs dome and the main heat path. It is based on thermal transient analysis of LED configurations with and without the dome. The heat paths de-embedding procedure proposed significantly increases accuracy of the LED thermal characterization compared to a typical singular heat path approach. The method is demonstrated with a representative mid-power LED. The results are validated with steady-state FEA. Suppressed estimation errors of the heat path evaluation are indicated. [ABSTRACT FROM AUTHOR]

The technology to produce compatibilized blends of liquid crystalline polymer and highly amorphous cyclic olefin copolymers through two novel approaches were studied. The first approach was to use silane-functionalized halloysite nanotube as nonspecific compatibilizer and the second method was reactive compatibilization. The study of blends and their resulting microstructure; their thermal, mechanical, and viscoelastic properties were investigated. The kinetic study of blends compatibilized through both routes was performed. [ABSTRACT FROM PUBLISHER]

As polymers have the ability to be easily molded in to any shape, they have a wide range of applications in industry. Composites prepared by dispersing ceramics in to polymer matrix have higher thermal conductivity than the original polymer, and they still retain their high electrical resistance. In this work, polyvinyl butyral (PVB) is chosen as the polymer matrix. Ceramic nanoparticles like boron nitride (BN), zinc oxide (ZnO) and silicon carbide (SiC) are used as fillers. Polymer composites with different filler loading ratio (wt %) are prepared and their thermal and electrical properties are analyzed. FT–IR, XRD and TGA characterizations are also performed on the composites. The results indicated that PVB composite with hexagonal boron nitride (h–BN) showed the best improvement in thermal conductivity up to 0.5194 W m −1 .K −1 which is an increase of 131.87%, and volume resistivity of composites remained high, above the 10 10 Ω–cm level. [ABSTRACT FROM AUTHOR]

Characterization of the thermal properties of the surface and subsurface structures of the skin can reveal the degree of hydration, the rate of blood flow in near-surface micro- and macrovasculature, and other important physiological information of relevance to dermatological and overall health status. Here, a soft, stretchable thermal sensor, based on the so-called three omega (i.e., 3ω) method, is introduced for accurate characterization of the thermal conductivity and diffusivity of materials systems, such as the skin, which can be challenging to measure using established techniques. Experiments on skin at different body locations and under different physical states demonstrate the possibilities. Systematic studies establish the underlying principles of operation in these unusual systems, thereby allowing rational design and use, through combined investigations based on analytical modeling, experimental measurements, and finite element analysis. The findings create broad opportunities for 3ω methods in biology, with utility ranging from the integration with surgical tools or implantable devices to noninvasive uses in clinical diagnostics and therapeutics. [ABSTRACT FROM AUTHOR]

In many theories and applications, generalized models can give a good head start for further research where the implementation of new elements and/or boundary conditions could become quite complex. In this paper the development of a compact thermal model of an infrared sensor will be presented. This thermal model includes not only the thermal resistances and capacitances of the sensor structure itself but the radiative and convective thermal resistances to the ambience and between the sensor plate and the heat source (thermal transfer impedance) which is important when the heat source and the sensor are in close proximity. Limitations and the applicability of the proposed model are also discussed. We also aim to present how the proposed model can be used for other IR sensor structures as well. [ABSTRACT FROM AUTHOR]

The specifications and aging of Li-ion batteries highly depends on temperature. Battery thermal models are therefore useful to improve the thermal management of battery packs. This study presents a method to determine the heat capacity and the anisotropic thermal conductivities of a Li-ion pouch cell. A single experimental setup is devised and involves local heating of the battery with a resistance heater. The thermal properties of the cell are then identified by calibrating an analytical thermal model with the experimental temperature data. A three-dimensional analytical model is developed for this purpose. It allows for simultaneous characterization of the cell anisotropy. The thermal properties are identified at 50% state of charge between 0 °C and 40 °C. Models with adiabatic and convection boundary conditions are compared and showed similar results. Overall, the values and tendencies agree with the literature. This non-destructive method can be directly applied to any pouch and prismatic cells, and adapted to cylindrical cell. • Thermal anisotropy of a pouch cell is characterized with a single experiment. • A three-dimensional analytical model is developed to determine the cell properties. • Methodology involves no state of charge deviation and little temperature deviation. • Heat capacity and through-plane thermal conductivity are linear vs. temperature. • Heat capacity and in-plane thermal conductivity increase with temperature. [ABSTRACT FROM AUTHOR]

The next generation of heterogeneous integration requires 2.5-D packages on through silicon interposer (TSI) as enabling technology for less signal delay, faster speed, and more functionality. In the meantime, the introduction of multiple chips on interposer tends to increase the heat density with added interconnect complexity, which requires systematic thermal analysis and characterization. In this paper, thermal characterization of 2.5-D packages on TSI is reported in both bare-die package and overmolded package formats. The test vehicle consists of two dummy chips and thermal test die assembled on the same interposer of 18~mm\times 18~mm\times 0.1~mm through the flip chip bumping and joining process. A thermal test chip of 5.08~mm\times 5.08~mm is built in with heaters and diodes for thermal characterization. Thermal measurements are conducted for thermal resistances from junction to the ambient, from junction to the board, and from junction to top casing. Measurement accuracy is improved through distributed through silicon via network, multidie temperature monitoring and uncertainty analysis and minimization. It is found that the overmolded package has lower thermal resistances than the bare die package. In addition, the thermal resistance from the junction to the casing is also characterized with a liquid-cooled minichannel cold plate as heat sink, indicating the vast difference between bare die package and molded package. Besides experimental measurements, thermal simulation models under different boundary conditions are established, respectively, to compare with the measurements. Good agreements are generally achieved between simulation and measurements. Further simulation is also conducted to examine the effects of overmold thickness and power dissipation from the multichips module on the interposer. [ABSTRACT FROM AUTHOR]

This paper presents the thermal and mechanical characterizations of a composite material made of plaster and home-made solid–solid Phase Change Material (s-s PCM) to be considered as a building material in order to: increase thermal inertia of buildings, improve comfort of the inhabitants, and reduce the primary energy needs of buildings. The use of those s-s PCM allows to avoid the problems of liquid–solid PCM that were considered into building materials. The s-s PCM involves a transition from polymeric amorphous to crystalline phase. They remain in a solid state under 100 °C and are water resistant. Physical properties of the s-s PCM are such that the grain size can be controlled for incorporation and mixing with plaster before water addition. The thermal properties of the composite were characterized by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Further composite is instrumented with K type thermocouple during exposition to thermal cycling around ambient temperature in a stove with fixed humidity. The microstructure of the PCM-bearing composite was observed by scanning electron microscopy (SEM). The incorporation of the PCM into the plaster matrix does not change the thermal properties of PCM. The thermal monitoring of the composite shows a modification of the maximum and the minimum peaks of temperature as well as a time offset of temperature variations. Some mechanical properties of the composite, such as compressive strength were investigated. Those preliminary results suggest that our s-s PCM can be considered further for incorporation into plasterboard that will passively contribute to a better thermal comfort in building application. [ABSTRACT FROM AUTHOR]

Abstract: In this paper PCM is added to three types of stabilized rammed. Mechanical and thermal characterization is carried out. To do so, the compressive strength is optimized and the final compositions obtained are used to formulate the materials which will be thermally characterized. The optimization process is done with a design of experiments (DoE) and a variance analysis (ANOVA). Finally, LCA is used to evaluate the environmental impact during the manufacturing phase, due to the addition of stabilizers and PCM in the rammed earth. [Copyright &y& Elsevier]

Abstract: Crystallization kinetics and thermal properties in superionic glasses Cu x Ag1− x I–Ag2O–V2O5 for x =0.1–0.3 have been thoroughly investigated. X-ray diffraction and differential scanning calorimetry measurements confirm the precipitation of at least three compounds during crystallization, viz. AgI, Ag4V2O7 and Ag8I4V2O7. The activation energies for structural relaxation (Es) and crystallization (Ec) obtained using Moynihan and Kissinger formulation exhibit interesting trends with CuI substitution. The Es value decreases with CuI substitution in the system. Further, the Ec values corresponding to precipitation of Ag4V2O7 and Ag8I4V2O7 exhibit increasing trend, whereas, for that of AgI precipitation a decreasing trend with CuI content. The Avrami parameter calculated from Augis–Bennett method and Ozawa equation suggests predominantly surface crystallization in the glassy system. The electrical conductivity–temperature (σ–T) cycles interestingly demonstrate increasing precipitation of AgI with CuI content in the glass matrix. [Copyright &y& Elsevier]

Norfloxacin (NFX) is a synthetic antibacterial drug. The development of extended release tablets improves the patients’ comfort and compliance, resulting in lower discontinuation of the therapy; with consequently decrease in bacterial resistance. In the present work, the thermal behavior of NFX was investigated using TG and DSC techniques. Isothermal and non-isothermal methods were employed to determine kinetic data of decomposition process. Compatibility studies between NFX and pharmaceutical excipients, including three hydrophilic polymers were carried out in order to develop a new formulation of NFX to obtain extended release tablets with an approved quality. [ABSTRACT FROM AUTHOR]

Abstract: The thermal properties and degradation behaviors of poly(norbornene-2,3-dicarboxylic acid dialkyl esters) (PNB-dialkyl esters) (alkyl=Me (PNB-Me), Et (PNB-Et), Pr (PNB-Pr), and Bu (PNB-Bu)) were investigated by thermogravimetric analysis (TGA) in dynamic conditions and by infrared (IR) spectroscopy. The PNB-dialkyl esters show good thermal stability up to 350°C, and the thermal stability decreases in the order Me>Et>Pr>Bu with the increase in size of side chain. The effect of side-chain size on the thermal degradation behaviors of PNB-dialkyl esters is evidenced by one-step thermal degradation profile for PNB-Me while two-step thermal degradation profile for PNB-Et, PNB-Pr, and PNB-Bu. Transformation is deduced to undergo β-hydrogen elimination and formation of anhydride group in the first stage of thermal degradation reaction according to TGA and IR results for PNB-Et, PNB-Pr, and PNB-Bu. The apparent activation energy and thermal degradation model of PNB-dialkyl esters are estimated by means of Ozawa–Flynn–wall method and Phadnis–Deshpande method, respectively. [Copyright &y& Elsevier]

For the first time, it is demonstrated in this letter that high-power silicon devices [diodes and insulated gate bipolar transistor (IGBTs)] can be forward biased and remains functional after cross sections. Sample preparation is presented, and electrical characterizations of a high-power diode and IGBT (600 V–200 A) have been performed in steady on-state. Infrared thermography on the cross-section surface using a macro-lens with high spatial resolution has allowed characterizing the vertical thermal distribution inside the power diode during forward bias. The impact of this work is that it opens a wide field of investigation in high-power semiconductor device characterization under forward bias. [ABSTRACT FROM AUTHOR]

Graphene aerogel (GA) as one of the innovative carbon nanostructured materials is superior with flexibility, strong mechanical strength, lightweight, high porosity and excellent durability, which attracted wide research interests and fulfill the requirements for various novel applications in energy conversion and storage, sensor, thermal management, and environment areas, etc. The thermal property among other important properties of GA is important for its novel applications. In this work, we first introduce the synthesis and microstructure control method for GA, including pore size control, anisotropic pore structure control, and heterostructure control. The methods for measuring the thermal conductivity of bulk GAs in air (apparent k) and the k of solid matrix of GAs are introduced in detail, respectively. Finally, we review the thermal transport models for GAs, including the air–solid coupling models, models for calculating the intrinsic thermal properties of graphene nanoflakes, as well as the thermal reffusivity model and dominating thermal contact resistance model. Challenges and opportunities in the study of thermal transport in 3D GAs are discussed. Considering the remarkable complexity of physical/chemical structure of GAs, there is still a large room in understanding fundamentals of energy transport in these three-dimensional graphene networks, which will pave the way toward their novel applications in the near future. [ABSTRACT FROM AUTHOR]

In this paper, LiNO3–NaCl binary mixed molten salt with high phase change enthalpy was selected as phase change materials (PCM). LiNO3 was used as the main phase change material, and NaCl was used as the additional material to change the properties and reduce the supercooling degree of molten salts. LiNO3–NaCl binary mixed molten salts with different mass proportion were prepared by static melting method. The optimum eutectic ratio of the mixed molten salt was obtained through analysis of the experiment results. The influence of NaCl on phase change temperature, decomposition temperature, supercooling degree and phase change latent heat were tested and analyzed. The properties of the phase change materials were characterized by thermogravimetric analyzer and simultaneous differential scanning calorimeter (TGA/DSC), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The phase transition temperature, latent heat and supercooling degree of the binary mixed molten salts showed nonlinear variation with the increase in NaCl mass fraction. When the mass ratio was 88:12 for LiNO3–NaCl, the phase change temperature was the lowest of 222.6 °C, the phase change latent heat was the highest of 389.3 J·g−1 and the supercooling degree was 1.2 °C. The optimum eutectic crystallization degree was achieved. At the same time, the decomposition temperature of the mixed molten salt was increased from 560 °C to 620 °C with the addition of NaCl, which greatly increased the applicable temperature range of LiNO3. [ABSTRACT FROM AUTHOR]