Thermal Characterization Research Articles

A comprehensive investigation of the impact of carbon-supported metal complexes of triaminoguanidine on the characteristics of a double-base propellant

ABSTRACT In this study, triaminoguanidine complexes grafted onto activated carbon (AC-TAG-Fe and AC-TAG-Co) were designed and investigated for their catalytic effect on the thermolysis of a double base propellant consisting of nitrocellulose (NC) and diethylene glycol dinitrate (DEGDN). The successful synthesis of transition metal complexes with triaminoguanidine and their subsequent grafting onto activated carbon were confirmed using various analytical techniques, including Fourier Transform Infrared Spectroscopy, Raman Spectroscopy, X-ray Diffraction, and Scanning Electron Microscopy. Thermal characterization using Thermogravimetric Analysis and Differential Scanning Calorimetry provided valuable insights into the thermal properties and reactivity of the elaborated NC/DEGDN-based composites. Importantly, the addition of various additives resulted in notable improvements in both the enthalpy of reaction and density. Isoconversional kinetic studies revealed that the incorporation of TAG-Fe and TAG-Co complexes reduced the apparent activation energy of the NC/DEGDN composite from 137.4 kJ/mol to 135.4 kJ/mol and 114.8 kJ/mol, respectively, suggesting their catalytic effect. Furthermore, it is found that the addition of activated carbon (AC) resulted in an increase in activation energy to 154 kJ/mol, whereas grafting TAG-Fe and TAG-Co complexes onto AC as a catalytic support subsequently reduced activation energy to 119 kJ/mol and 112 kJ/mol, respectively. Overall, this research serves as a valuable reference for future studies focusing on investigating the catalytic combustion characteristics of double-base solid propellants.

Thermal Characterization of Ultrathin MgO Tunnel Barriers.

Magnetic tunnel junctions (MTJs) with ultrathin MgO tunnel barriers are at the heart of magnetic random-access memory (MRAM) and exhibit potential for spin caloritronics applications due to the tunnel magneto-Seebeck effect. However, the high programming current in MRAM can cause substantial heating which degrades the endurance and reliability of MTJs. Here, we report the thermal characterization of ultrathin CoFeB/MgO multilayers with total thicknesses of 4.4, 8.8, 22, and 44 nm, and with varying MgO thicknesses (1.0, 1.3, and 1.6 nm). Through time-domain thermoreflectance (TDTR) measurements and thermal modeling, we extract the intrinsic (∼3.6 W m-1 K-1) and effective (∼0.85 W m-1 K-1) thermal conductivities of annealed 1.0 nm thick MgO at room temperature. Our study reveals the thermal properties of ultrathin MgO tunnel barriers, especially the role of thermal boundary resistance, and contributes to a more precise thermal analysis of MTJs to improve the design and reliability of MRAM technologies.

Mechanical, Thermal, and Morphological Analysis of Himalayan Agave Fiber /GO Coated Fly Ash Hybrid Polypropylene Composites.

Composites containing two different types of reinforcements offer a wide range of possibilities and synergistic properties. This study investigates the hybridization effect of chemically active fly ash (FA) (5 wt.%) on the composites made from alkali (1 wt.%) - APTES silane (2 wt.%) treated Himalayan agave fibers (HAF) (25 wt.%) and polypropylene (PP). Prior to FA activation, the planetary ball mill was used to suitably reduce the particle size of the FA with was confirmed by the dynamic light scattering approach. Secondary reinforcement FA was modified with APTES silane (1 wt.%), followed by treatment with graphene oxide (GO) (0.5, 0.75, and 1 wt.%). The highest tensile strength of 40.47 MPa and modulus of 1.49 GPa were observed for the hybrid composites fabricated from 0.75 and 1.0 wt.% GO treated fly ash. Interestingly, this trend differed for flexural properties, and the highest flexural strength of 53.52 MPa was demonstrated by 0.5 wt.% GO treated FA hybrid composite. Thermal characterization revealed that addition of fiber increased crystallinity but decreased thermal stability, whereas a good wettability of the fiber and FA in matrix was demonstrated through morphological characterization.

Thermal kinetic analysis and characterization of water hyacinth biomass for renewable energy application

Thermal kinetic analysis and characterization of water hyacinth biomass for renewable energy application

Thermal characterization of Ge-rich GST thin films for phase change memories by Raman thermometry

Thermal characterization of Ge-rich GST thin films for phase change memories by Raman thermometry

Enhancing Aviation Safety: Multifunctional Graphene Nanostructured Foams for Lightweight Fire Suppression Materials

Fuel tank fires and explosions are the primary causes of military and civilian aircraft losses and have been a major concern for the aviation and defense industries. Passive protection systems with explosion-suppression materials generate a protected environment within fuel tanks before ignition can occur and help prevent catastrophic failures. To minimize these concerns, open-cell reticulated polyurethane foams are extensively used in passive protection systems. However, fire- and explosion-related incidents are still taking place and need to be urgently addressed for aviation safety. This study investigates the effects of graphene nanostructured foams for redesigning the next-generation lightweight fire-retardant materials in aviation. Graphene foams have a unique open-cell morphology with three dimensional (3D) continuous and interconnected network structures and hollow features, which can be suitable for aircraft and defense applications. In this study, mechanical and thermal characterizations tests were conducted on graphene nanostructured foams for a better evaluation. Mechanical loading-unloading studies highlighted their outstanding mechanical energy-absorption capabilities against external loads. The thermogravimetric analysis revealed that the graphene foams provided excellent thermal properties against fire and high-temperature degradation. It was also confirmed that graphene foams uniquely manifested self-extinguishing characteristics during burning tests without catching fire or dripping for secondary fire formations. According to the tube explosion experiments, the graphene foams kept their appearance and strength after blast impacts and elevated explosion temperatures and shock waves. As a result, the proposed multifunctional graphene micro- and nanofoams offer significant potential for the next-generation fire- and explosion-suppression materials in various critical industries, such as aircraft, defense, space, drone, energy, and automotive.

Effect of B/Pb ion replacement in B2O3-PbO-SiO2 glasses: structural, thermal, optical and electrical properties

Due to its easy manufacturing process and outstanding physical and chemical characteristics, boron lead silicate glass is widely used in electronic packaging, optical fields, and sensor technology. Herein, new glass samples with different proportions of B2O3/PbO are prepared by a combined melting and annealing process. The glasses undergo structural and thermal characterization to investigate its composition, thermal behavior, optical properties, and dielectric properties. The results show that the glass structure changes gradually as [SiO4] and [PbO4] units were replaced by [BO3] units with increasing B2O3 content. This transformation has an impact on coefficient of thermal expansion and characteristic temperature of the glass. Additionally, it is observed that alterations in structure resulted in a decrease in both optical band gap as well as dielectric constant and loss. These findings provide insights into how variations in the B2O3/PbO ratio influence structural evolution and enhance properties for boron lead silicate glasses. This provides a theoretical basis for further advances to improve material properties and expand optical and electronic applications.

Thermal behavior of construction and demolition waste-based geopolymer

Unsorted Construction and Demolition Waste (CDW) from residential building was tested as solid precursor for obtaining eco-sustainable alkali activated materials with potential applications in the building industry. Suitable reactive systems for material consolidation were tested, including alkaline solutions of sodium hydroxides and/or silicates at different concentrations. Metakaolin (MK) was also tested as an additional precursor together with CDW in different ratios to optimize geopolymerization. An MK/CDW weight ratio of 40/60 and sodium silicate as alkaline activator allowed the production of a well-reacted and cohesive material, with a bulk density of 1.35 g/cm3, a monomodal mesoporosity with a modal pore size of 0.0214 µm (open porosity ∼42 vol%), and a compressive strength of 25 MPa, thus showing similar features to those of pure metakaolin based-geopolymers. Thermal characterization was performed up to 1000°C showing that the material can exhibit thermal stability up to 650°C. Above that temperature a shrinkage due to viscous flow occurred, followed by an expansion over 750°C with the formation of macropores and dense struts. Based on these results, the developed CDW-based geopolymer has the potential for use in green building applications, with adequate thermal stability up to medium-high temperatures.

Tiger nut (Cyperus esculentus L.) oil-whale spermaceti wax oleogels with banana and coconut flavors: physicochemical, thermal, and rheological characterization

Tiger nut (Cyperus esculentus L.) oil-whale spermaceti wax oleogels with banana and coconut flavors: physicochemical, thermal, and rheological characterization

Synthesis and thermal characterization of polyesters and copolyesters containing selenium with potential self‐healing behavior

AbstractThis work presents a versatile method for obtaining a new family of selenium‐containing polyesters through polycondensation reactions, focusing on methodology of the synthesis, thermal characterization, and evaluation of potential self‐healing behavior of these structures. Using diselenides as monomers, homopolymers and copolymers with self‐healing behavior were synthesized in good yields and molar masses, and their structural characteristics could be modulated according to the type of monomers and their proportions. In this way, a wide range of polymers were obtained using monomers with aliphatic and aromatic structures. All the synthesized polymers were evaluated in terms of their thermal stability, which reached 200°C, and their completely amorphous structure, where the Tg could be modulated by adjusting the proportion of monomers. In addition, the self‐healing potential of polymers that were able to form films and exhibited structural mobility at room temperature was qualitatively evaluated. After 12 h of exposure to visible light at a controlled temperature, the structures containing aromatic and aliphatic mixtures at a 1:1 ratio were able to regenerate almost 100% of their surface area. The results presented in this work can contribute to the development of new methodologies for obtaining selenium‐containing polymers while increasing the range of possible self‐healing compounds.

Electro-optical and thermal characterization of copper tartrate crystals grown in silica gel

Copper Tartrate crystals were grown by Gel Growth technique by single diffusion. Silica gel of Optimum specific gravity was set with tartaric acid at optimum pH and aging period. Band gap of copper tartrate crystal is determined using UV-Visible spectroscopy to be 5.24 eV. In PL spectra broad peak is observed at nearly 367.44186 nm in the range 287 nm to 458 nm along with the sharp, intense transmission maxima peak at wavelength nearly 505.03876 nm which is characteristic of a material composition and electronic band structure. This shows the transparency in UV-visible region and material is a filter in this range .TGA analysis concluded that Copper tartrate has one half water molecule as crystalline water and is stable up to 85.02 0 C.DSC analysis assigns the temperature value 314.5 0C as melting point and apparent enthalpy of fusion determined is 10.18 mW.

Thermal Decomposition and Kinetic Analysis of Amazonian Woods: A Comparative Study of Goupia glabra and Manilkara huberi

This study presents a detailed analysis of the thermal degradation and kinetic behavior of two Amazonian wood species, Goupia glabra (cupiúba) and Manilkara huberi (maçaranduba), using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR-ATR), and direct infusion mass spectrometry (DIMS). Wood samples were subjected to controlled heating rates of 20, 40, and 60 °C/min from 25 to 800 °C under an argon atmosphere. TGA revealed moisture evaporation below 120 °C, with hemicellulose degradation occurring between 220 and 315 °C, cellulose decomposition between 315 and 400 °C, and lignin breakdown over a broader range from 180 to 900 °C. The highest rate of mass loss occurred at 363.99 °C for G. glabra and 360.27 °C for M. huberi at a heating rate of 20 °C/min, with shifts to higher temperatures at faster heating rates. Activation energies were calculated using Arrhenius and Kissinger models, yielding values between 53.46–61.45 kJ/mol for G. glabra and 58.18–62.77 kJ/mol for M. huberi, confirming their stable thermal profiles. DSC analysis identified a significant endothermic peak related to moisture evaporation below 100 °C, followed by two exothermic peaks. For G. glabra, the first exothermic peak appeared at 331.45 °C and the second at 466.08 °C, while for M. huberi, these occurred at 366.41 °C and 466.08 °C, indicating the decomposition of hemicellulose, cellulose, and lignin. Enthalpy values for G. glabra were 12,633.37 mJ and 18,652.66 mJ for the first and second peaks, respectively, while M. huberi showed lower enthalpies of 9648.04 mJ and 14,417.68 mJ, suggesting a higher energy release in G. glabra. FTIR-ATR analysis highlighted the presence of key functional groups in both species, with strong absorption bands in the 3330–3500 cm−1 region corresponding to O-H stretching vibrations, indicative of hydroxyl groups in cellulose and hemicellulose. The 1500–1600 cm−1 region, representing aromatic C=C vibrations, confirmed the presence of lignin. Quantitatively, these results suggest a high content of cellulose and lignin in both species. DIMS analysis further identified polyphenolic compounds and triterpenoids in M. huberi, with major ions at m/z 289 and 409, while G. glabra showed steroidal and polyphenolic compounds with a base peak at m/z 395. These findings indicate the significant presence of bioactive compounds, contributing to the wood’s resistance to microbial degradation. This comprehensive thermal and chemical characterization suggests that both species have potential industrial applications in environments requiring high thermal stability.

The Regulation of Temperature Fluctuations and Energy Consumption in Buildings Using Phase Change Material–Gypsum Boards in Summer

This study examined the thermal performance of Comfortboard23, a commercial gypsum board from Knauf infused with phase change material (PCM). Structural characterization using XRD and SEM confirmed the presence of microencapsulated PCM within the gypsum matrix. The study does not provide a direct comparison between Comfortboard23 and other PCM-integrated gypsum boards on the market. This is a limitation of the research. A comprehensive comparison would involve testing multiple products under identical conditions, and evaluating factors such as thermal performance, cost-effectiveness, durability, and ease of installation. Thermal characterization involved a novel low-scale thermal chamber to measure U-value, thermal conductivity, heat storage capacity, and dynamic thermal response. Results showed incorporating PCM decreased the U-value by 2% compared to standard gypsum boards. Additionally, PCM inclusion increased heat storage capacity by around 45% and improved dynamic thermal characteristics by decreasing thermal stability coefficient from 0.92 to 0.76 and increasing thermal lag from 0.27 to 0.49 h. The 45% increase in heat storage capacity of Comfortboard23 could lead to a 10–20% reduction in heating and cooling energy consumption, improved thermal comfort, and potential HVAC downsizing. Exact benefits depend on climate, building design, and occupancy patterns, necessitating further research in diverse real-world settings. The findings demonstrate Comfortboard23’s potential for enhancing thermal energy storage in buildings, contributing to energy savings, improved thermal comfort, and reduced temperature fluctuations across varying daily temperatures. Overall, the study highlights the promise of Comfortboard23 as an energy-efficient PCM-integrated building material.

Measurement and thermal characterization of graywater discharge events for house-central collection systems in the context of heat recovery

Measurement and thermal characterization of graywater discharge events for house-central collection systems in the context of heat recovery

Synthesis, Optical, Electrical, Fluorescence, Dielectric, Thermal, and Mechanical Characterization of 3-Aminopyridine (Scaffold in Drugs) Single Crystal

Objectives: To screen the optical, electrical, fluorescence, dielectric, thermal, and mechanical behavior of the 3-aminopyridine single crystal for its suitability in optoelectronic applications. Methods: A good single crystal of 3-aminopyridine (3-AP) was grown by the slow evaporation method. Findings: The lattice parameters of the grown crystal were determined using a single crystal X-ray diffractometer as, a = 6.184 (4) Å, b = 15.350 (6) Å, c = 5.361 (7) Å and the required functional groups C-N, NH2 bonds of 3-AP were recognized by the FTIR studies. The grown crystal was screened using the UV-Vis-NIR spectrum to understand the transmission and absorption character of the crystal. The various optical constants such as absorption coefficient, optical conductivity, and electrical conductivity of the crystal have been determined from the UV-Vis transmission plot. The lower cut-off wavelength of the 3-AP crystal was observed at 250 nm. The band gap of the grown crystal is found to be 4.5 eV. The emission property of the crystal was studied using fluorescence spectra. Violet, blue, and red emissions are observed from the fluorescence spectra. Thermal screening of the 3-AP crystal was performed using TGA and DTA. The 3-AP crystal remains stable up to 220 ºC and then the crystal begins to decompose up to 260 ºC due to the loss of the -NH2 group of the 3-aminopyridine. The Vickers hardness test revealed the nature of the material as soft type with Meyer’s index (n) of 2. The electronic polarization behavior of the crystal was examined using the dielectric study. Novelty: The lower cut-off wavelength of 250 nm, wide band gap of 4.5 eV, excellent transparency in the entire visible and near-infrared region, violet, blue, and red emission by the material are the distinguishing and mandatory features for optoelectronic applications. These features are good as compared to the 3-AP derivatives reported earlier. Keywords: Unit cell, Absorption, Emission, Conductivity, Strength, Loss

Thermal characterization of plat heat exchanger made from polymer biocomposite reinforced by silicon carbide

Thermal characterization of plat heat exchanger made from polymer biocomposite reinforced by silicon carbide

A cotton waste reinforced composite for automotive applications: development and thermal characterization

Fibre-reinforced composites are largely used in automobiles and building materials in various forms. Thermal insulation and acoustic characteristics are being mainly considered in building construction and automotive applications to meet overall comfort conditions as well as fulfil energy efficiency requirements. It is critical to look for new and sustainable approaches to increasing the thermal characteristics of the composites. Integration of various wastes is one of the most sustainable and efficient methods for increasing the thermal characteristics of composites. The present work is aimed to investigate the thermal insulation performance of cotton waste-reinforced composites using both epoxy and modified epoxy using the C-THERM thermal conductivity analyzer according to ASTM C518 standards. A computational model of randomly dispersed epoxy matrix interphase with cotton fibers is developed and validated with experimental results. It was observed that the thermal conductivity is higher when the combination of 40% flake cotton waste and 60% matrix material is used, both for epoxy and modified epoxy. The thermal conductivity for epoxy composites is 0.5715 W/mK, while for modified epoxy composites it is 0.4935 W/mK. The results indicate that modified epoxy composites exhibit better thermal insulation properties, as they have lower thermal conductivity values compared to epoxy composites. The modified epoxy composite is considered the best for thermal insulation, can be utilised in various automotive applications, such as partitioning panels, automotive panels, brake pads, and similar applications.

Thermal characterization analysis of pool fire affected by sealing in coal mine dead-end roadways: an experimental study

Thermal characterization analysis of pool fire affected by sealing in coal mine dead-end roadways: an experimental study

Thermal Characterization of Textile Waste Materials for Reuse in the Energy Refurbishing of Buildings

The study’s findings suggest new applications for End-of-Life Household Materials (EoLHMs), with a focus on new materials derived from textile wastes. The aim is twofold: explore innovative methods to promote the circular economy by reusing EoLHMs in the building sector and refurbishing buildings with particular attention to home-made panels, to favour disadvantaged contexts. Three different materials were tested, and their thermal conductivity was measured according to the ISO 8301 standard. The thermal conductivity as a function of the density was also investigated for a material derived from hemp. Comparisons with other textile materials are presented as well. As a result, the thermal conductivity of the materials ranged from 0.035 to 0.049 W/(m K), typical for insulating materials used in refurbishing applications.

Impact of cellulose enrichment on castor oil polyurethane sheets: A path to greener materials

AbstractDue to the growing concern over the depletion of the global crude oil stock and environmental issues, the replacement of petroleum‐based polymers with environmentally benign alternatives derived from renewable resource has attracted great attention. In the current study, four different polyurethane (PU) sheets were synthesized from unmodified castor oil (CO) and hexamethylene diisocyanate (HDI), incorporating cellulose nanofibers (CNF) as a filler. The mixture consisting molar ratio of CO, HDI, and CNF in a ratio of 1:5:0.8 yielded the best results. This formulation achieved a tensile strength of 22.55 MPa and an elongation at break of 55.9%. Additionally, the resulting PU sheets exhibited excellent thermal properties, with a glass transition temperature (Tg) and melting temperature (Tm) that were notably enhanced, further highlighting the effectiveness of this specific mixture in producing high‐performance, bio‐based PUs. Fourier‐transform infrared spectroscopy (FTIR), thermal, and mechanical characterizations indicated that both reinforced and unreinforced PU exhibited properties within acceptable ranges. Given the bio‐based origins of CO and cellulose, the synthesized polymers are biodegradable and suitable for biomaterial applications. The study confirms that the bio‐based origins of CO and cellulose render synthesized polymers biodegradable, suitable for various biomaterial applications.