Thermal Decomposition Research Articles

Simulation-Based Investigation on Thermal Propagation in Li-ion Battery Modules with regard to the Thermal Management System

Abstract Thermal propagation in Li-ion battery systems is affected by a wide range of influencing factors including chemical cell properties as well as thermal transport phenomena. Due to the dependence on thermal surroundings it is crucial to regard the entire battery system including peripheral components when assessing thermal runaway and propagation risks. This study proposes a simulation-based approach to support design and dimensioning of potential safety measures. It is based on a chemical model for the thermal runaway decomposition reactions combined with 3D thermal simulations. This is applied on exemplary ten cell battery pack in order to investigate on effects on heat transfer during thermal propagation. Insulation and cooling systems are included in the simulation environment for that purpose. It is found that propagation behavior significantly depends on their positioning within in pack and on thermal boundary conditions. Placing too many barriers may exacerbate hazardous situations instead of mitigating them due to heat accumulation effects. Cooling systems are shown to be able to support thermal runaway mitigation strategies but their effectiveness is limited by thermal transport inside the battery cells.

Chemiluminescence-based evaluation of styrene block copolymers' recyclability.

The study presents the chemiluminescence based (CL) evaluation of the recyclability of linear styrene block copolymers. This analysis can provide insight into the material's degradation state and predict its suitability for further recycling cycles, helping to avoid unnecessary energy consumption during processing.The thermal stability of four similar copolymer structures - styrene-isoprene-styrene (SIS), styrene-butadiene-styrene (SBS) copolymers with different styrene/butadiene ratios, and styrene-ethylene-butadiene-styrene (SEBS) - was studied using isothermal and non-isothermal chemiluminescence (CL). The activation energies for oxidative degradation were calculated based on oxidation induction times indicated by the CL intensities evolution. The results, which highlight the influence of molecular structure on stability under aging conditions, as presented by the calculated for the activation energy (kJ mol-1), show the following sequence: SBS (styrene 30%) (117kJ mol-1) ≈ SIS 120 (kJ mol-1) < SBS (styrene 40%) (176kJ mol-1) < SEBS (180kJ mol-1). The CL data were correlated with infrared (IR) spectroscopy and differential scanning calorimetry (DSC) data, providing a comprehensive understanding of the thermal stability and degradation mechanisms during recycling proces. The sequence of the composing units determines the degradation process, with weaker points predominantly attacked in the linear moieties of isoprene, butadiene, and vinyl segments. The experimental data indicate that SIS and SBS (30% styrene) copolymers degrade the fastest likely due to the rapid accumulation of hydroperoxide radicals. The SEBS copolymer also experiences significant degradation, but this occurs at higher temperatures (above 220 ⁰C) and progresses more gradually once it begins. In contrast, the SBS copolymer with 40% styrene content degrades more slowly and exhibits minimal mass loss, primarily due to the formation of less reactive keto degradation products.

Kinetics of Thermal Decomposition of Carbon Nanotubes Decorated with Magnetite Nanoparticles

Kinetics of Thermal Decomposition of Carbon Nanotubes Decorated with Magnetite Nanoparticles

Enhanced Rheological and Structural Properties of the Exopolysaccharide from Rhizobium leguminosarum VF39 Through NTG Mutagenesis

Microbial exopolysaccharides (EPSs) are biopolymer materials with advantages such as biodegradability, biocompatibility, ease of mass production, and reproducibility. The EPS that was isolated from Rhizobium leguminosarum bv. viciae VF39 is an anionic polysaccharide with a backbone structure consisting of one galactose, five glucose molecules, and two glucuronic acids, along with 3-hydroxybutanoyl, acetyl, and pyruvyl functional groups. Through N-methyl-N′-nitro-N-nitrosoguanidine (NTG) mutagenesis, we isolated and purified a mutant EPS from VF39, VF39 #54, which demonstrated enhanced physicochemical and rheological properties compared to the wild-type VF39. The EPS structure of the VF39 #54 mutant strain showed a loss of glucuronic acid and 3-hydroxybutanoyl groups compared to the wild-type, as confirmed by FT-IR, NMR analysis, and uronic acid assays. The molecular weight of the VF39 #54 EPS was 250% higher than that of the wild-type. It also exhibited improved viscoelasticity and thermal stability. In the DSC and TGA analyses, VF39 #54 had a higher endothermic peak (172 °C) compared to the wild-type (142 °C), and its thermal decomposition point was 260 °C, surpassing the wild-type’s value of 222 °C. Additionally, the VF39 #54 EPS maintained a similar viscosity to the wild-type in various pH, temperature, and metal salt conditions, while also exhibiting a higher overall viscosity. The cytotoxicity test using HEK-293 cells confirmed that the VF39 #54 EPS was non-toxic. Due to its high viscoelastic properties, the VF39 #54 EPS shows potential for use in products such as thickeners, texture enhancers, and stabilizers. Furthermore, its thermal stability and biocompatibility make it a promising candidate for applications in food, pharmaceuticals, and cosmetic formulations. Additionally, its ability to maintain viscosity under varying environmental conditions highlights its suitability for industrial processes that require consistent performance.

A study of chemical composition and physical-mechanical properties of rigid polyurethane-polyisocyanurate foams changes under conditions of extreme heating

Polyurethane-polyisocyanurate rigid (PIR) foams are used as thermal insulation materials in a wide range of applications such as construction and pipe insulation. Some of the utilizations require the maximum operating temperature of these materials to reach extremely high temperatures. This work is devoted to the study of changes in the chemical composition and the main physical-mechanical and thermophysical characteristics of PIR foams subjected to prolonged extreme heating in the presence of the material direct contact with air and in its absence. Based on the results obtained, prolonged extreme heating of such materials leads to a significant change in their chemical composition, mainly due to the thermal decomposition of allophanate, urethane and urea linkages, as well as the gradual formation of uretidione, linear carbodiimide polymer and the oxidation of ethers to esters. The relative compressive strength of these materials changes only to a small extent, while the thermal conductivity of these materials increases significantly during heating.

A Bio-Based Polybenzoxazine Derived from Diphenolic Acid with Intrinsic Flame Retardancy, High Glass Transition Temperature and Dielectric Properties.

A bio-based benzoxazine monomer, diphenolic methyl ester hexafluoro diamino benzoxazine (DPME-HFBz), was successfully synthesized from diphenolic acid (DPA), and the chemical structure was successfully verified. The curing kinetics were studied via non-isothermal differential scanning calorimetry (DSC). The activation energies of DPME-HFBz were calculated by Kissinger and Ozawa methods to be 136.15 and 139.92 kJ/mol, respectively, and the reaction order was calculated to be first order. Owing to the large number of hydrogen bonds after polymerization, poly(DPME-HFBz) presented an ultra-high glass transition temperature of 312 °C and a high initial decomposition temperature (350 °C under air and 345 °C under nitrogen). Because of the excellent charring ability (50.2% residue under nitrogen), the LOI value of poly(DPME-HFBz) was as high as 38%. Poly(DPME-HFBz) also exhibited a very low heat release capacity (HRC) of 90 J/(g·K). In addition, poly(DPME-HFBz) had a dielectric constant (Dk) of 1.88 at 1.5 MHz, which was much lower than the Dk of the reported low-dielectric polymers. This work provides an efficient and sustainable strategy for the synthesis of benzoxazine thermosetting materials with excellent comprehensive properties.

Analysis and Characterization of Pericopsis mooniana Seed Oil for Potential Applications in Cosmetics and Nutritional Supplements

Pericopsis mooniana is renowned for wood applications, while its bark and leaves find uses in ayurvedic medicine. The shifting of global cosmetic and nutritional supplement industries towards plant-based oils has led to explore novel sources. No prior studies were done on P. mooniana seed oil. Therefore this study aims to characterize the seed oil of P. mooniana by determining Fatty Acids (FA) composition as their methyl esters, nonpolar constituents in unsaponifiable matter, and other physio-chemcial properties. The oil was extracted using the soxhlet extraction method. Ash and moisture contents of seeds, Acid Value (AV), Iodine Value (IV), smoke point and thermal stability of oil were also determined. Prepared fatty acid methyl esters and chemical constituents in unsaponifiable matter were identified and quantified using Gas Chromatography-Mass Spectrometry method. Results indicated a substantial oil yield of 36.71± 0.01% with moisture content of 5.60 ± 0.19%, ash content of 3.65 ± 0.38%, AV of 2.97 ± 0.40 mg KOH/g, IV of 16.02 ± 0.14 g I2/100g, smoke point of 233.6 ± 8.57°C, decomposition temperature of 409.95 ± 1.74°C and yield of unsaponifiable matter of 1.35 ± 0.01%. The dominant FAs are oleic (41.02%) and linoleic (38.12%) acids. Major unsaponifiable matter constituents are squalene (4.01 mg/g), beta.-sitosterol (2.63 mg/g), stigmasterol (1.23 mg/g), phytol (1.45 mg/g), geranylgeraniol (1.03 mg/g) and amyrin (0.95 mg/g). Based on the finding of this study, it can be concluded that P. mooniana seed oil has the potential to be utilized in both cosmetic and nutritional supplement industries.

Thermoanalytical and Kinetic Studies for the Thermal Stability of Emerging Pharmaceutical Pollutants Under Different Heating Rates

Emerging pharmaceutical pollutants like ciprofloxacin (CIP) and ibuprofen (IBU) are frequently detected in aquatic environments, posing risks to ecosystems and human health. Since pollutants rarely exist alone in the environment, understanding the thermal stability and degradation kinetics of these compounds, especially in mixtures, is crucial for developing effective removal strategies. This study therefore investigates the thermal stability and degradation kinetics of CIP and IBU, under different heating rates. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were employed to examine the thermal behavior of these compounds individually and in mixture (CIP + IBU) at heating rates of 10, 20, and 30 °C/min. The kinetics of thermal degradation were analyzed using both model-fitting (Coats–Redfern (CR)) and model-free (Kissinger–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO), and Friedman (FR)) methods. The results showed distinct degradation patterns, with CIP decomposing between 280 and 550 °C and IBU between 152 and 350 °C, while the mixture exhibited multistep decomposition in the 157–500 °C range. The CR model indicated first-order kinetics as a better fit for the degradation (except for IBU). Furthermore, CIP exhibits higher thermal stability and activation energy compared to IBU, with the KAS model yielding activation energies of 58.09 kJ/mol for CIP, 11.37 kJ/mol for IBU, and 41.09 kJ/mol for CIP + IBU mixture. The CIP + IBU mixture generally showed intermediate thermal properties, suggesting synergistic and antagonistic interactions between the compounds. Thermodynamic parameters (ΔH°, ΔG°, ΔS°) were calculated, revealing non-spontaneous, endothermic processes for all samples (except in the FWO method) with a decrease in molecular disorder and positive ΔG° values across all models and heating rates. The study found that higher heating rates led to less thermodynamically favorable conditions for degradation. These findings provide important information concerning the thermal behavior of these pharmaceutical pollutants, which can inform strategies for their removal from the environment and the development of more effective waste-treatment processes.

Thermal degradation of polytetrafluoroethylene, modified polytetrafluoroethylene, and their nanocomposites with boron nitride nanobarbs: Lifetime predictions and kinetic analysis

AbstractFlexible polymeric materials including dielectric thermal interface materials (TIMs) used in integrated circuits and other high frequency applications are exposed to extreme thermal and electrical conditions during their service life. Insight into the in‐use thermal stability and material lifetime is valuable to maintaining performance durability and preventing premature failure in actual end use. Herein, the thermal stability of polytetrafluoroethylene (PTFE), modified PTFE and their nanocomposites with recent generation boron nitride nanobarbs (BNNBs) was investigated based on lifetime prediction from thermogravimetric analysis and tensile strength deterioration of heat‐aged samples. Additionally, thermal degradation kinetics and mechanism was investigated using the model‐free advanced isoconversional method based on changing activation energy. The result shows that BNNB extends the lifetime of the PTFE by an order of magnitude. The degradation mechanism proposed from TGA‐MS result is supported by the multistep degradation mechanism identified in the kinetic computation. These results are valuable for predicting materials' in‐use lifetime to avoid premature failure.

Thermal Oxidation Degradation Characteristics and Kinetic Analysis of Waste Shell Powders for Efficient Utilization and Environmental Protection

ABSTRACT The thermal oxidation degradation and kinetic behavior of four waste shell powders: Hyriopsis cumingii, abalone, scallop, and clam were investigated. The thermal oxidation degradation process was elucidated using thermogravimetric analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and the Coats-Redfern method. This process typically occurs in four stages, with the decomposition of CaCO₃ (Stage III) being pivotal. Notably, clam and scallop powders exhibited the highest CaO yields of approximately 55.1% and 55.0%, respectively. Although abalone powder had a lower yield of 50.2%, it demonstrated the lowest activation energy of 118.08 kJ/mol in Stage III, suggesting potential energy and cost savings during CaO conversion. High-temperature calcination altered the chemical composition and microstructure of the shell powders, resulting in rough and porous CaO surfaces conducive to heavy metal ion and pollutant adsorption. The research provides a theoretical framework and experimental validation for the sustainable utilization of calcined shell powders, fostering efficient shell resource management and environmental protection.

Design and Synthesis of Aggregation‐Caused Quenching Hydroxy‐Phenanthroimidazole Derivatives for Probing of Fe3+ Ions and as Potential Blue Light Emitters

AbstractFluorescence aggregated molecules tend to employ versatile opportunities in metal ion probe sensors and fluorescent lighting. To achieve this dual challenging task, currently synthesized three phenanthroimidazole‐naphthalene‐based compounds Pq‐tBu‐OH, Pq‐mF‐OH, and Pq‐pF‐OH are derived based on substitution at N1 position for better photophysical and electrochemical properties. Compared experimental and theoretical calculations define the highest bandgap to be 2.75 eV of Pq‐pF‐OH, and the same molecule expressed a higher (348 °C) thermal decomposition. The calculated singlet and triplet energies found in the range of 3.24–3.67 and 2.70–2.72 eV indicate well energy transfer from S1→S0 (quantum yield of 23.36 %, lifetime is 4.05 ns). Among the numerous morphologies, the solid form exhibited improved intensive deep blue emission (x=0.159, y=0.051), and its InGaN LED results demonstrated a strong deep blue emission at 418 nm. Moreover, the fluorophores were experimentally visualizing the aggregation‐caused quenching (ACQ) which enables the probing of Fe3+ ion. However, for the first time, the ACQ‐assisted concept is applied through synthesized molecules for Fe3+ ion probing via fluorescence spectra, Job's plot calculation, and 1H NMR results. In addition, the probe works excellently at a detection limit of 10 μM and it could also act as a potential competitor for lighting applications.

Strongly toughened heat‐resistant cyanate ester resin‐based coatings doped by Tb3+‐complex anchored‐uCNTs with green fluorescent properties

AbstractThermally stable polymeric coatings are widely used for metal protection at high temperatures, but their brittle weakness makes them unavailable to durable environment. To overcome that, we report properties of cyanate ester resin (CER) coating doped with unzipped carbon nanotubes (uCNTs) loaded with terbium complex (TBP) as nanofiller. The performance of the coating showed that the bending flexibility, adhesion, and impact resistance of the doped coatings was significantly improved. The cylinder bending test showed that the minimal bending diameter of CER doped with TBP‐uCNTs coating reached 6 mm without failure, which represents a significant improvement compared to the pure CER coating (18 mm). Surprisingly, the impact resistance reached the highest value of 50 cm without any failure of the coating. X‐ray diffraction, Fourier transform infrared spectroscopy, Raman, x‐ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy studies of CNTs, uCNTS, TBP‐uCNTs, and properties of CER indicate that formation of CER/TBP‐uCNTs composite is supported by a chemical reaction between hydroxyl groups of TBP‐uCNTs and the cyanate groups of CER resulting in fabrication of a solid cross‐linked structure. The thermal decomposition temperature of the coating increases from 409°C for pure CER to 453°C for CER/TBP‐uCNTs. The fluorescence spectra show that CER/TBP‐uCNTs exhibits strong luminescence at 550 nm.

Skeletal Editing of Energetic Materials: Acid-Catalyzed One-Step Synthesis of Bridged Triazoles as High-Energy-Density Materials via the Nef Reaction.

Thermally stable insensitive energetic materials have captivated significant attention from the global research community due to their potential impact. In this study, a series of symmetric and asymmetric nitromethyl-bridged triazole compounds were synthesized from pyrimidine moieties via a skeletal editing approach. Additionally, carbonyl-bridged compounds were synthesized in a single step by using acid-catalyzed Nef reactions from their nitromethyl precursors. Peripheral modifications of pyrimidine resulted in fused energetic moieties. All synthesized compounds were fully characterized by using infrared spectroscopy, high-resolution mass spectrometry, multinuclear magnetic resonance spectroscopy, elemental analysis, and differential scanning calorimetry. Single-crystal X-ray diffraction analysis confirmed the structures of compounds 4 and 10. The newly synthesized moieties exhibit densities ranging from 1.75 to 1.86 g cm-3, detonation velocities between 8044 and 8608 m s-1, and detonation pressures between 23.10 and 30.31 GPa. Notably, compounds 9 and 10 demonstrate exceptional heat resistance, with decomposition temperatures of 315 and 335 °C, respectively. Computational studies, including density functional theory, quantum theory of atoms in molecules, noncovalent interactions, and electrostatic surface potential analysis, account for hydrogen-bonding and noncovalent interactions. This work highlights the potential of skeletal editing in the development of high-performing, thermally stable energetic materials.

Synthesis, Functionalization, and Biomedical Applications of Iron Oxide Nanoparticles (IONPs)

Iron oxide nanoparticles (IONPs) have garnered significant attention in biomedical applications due to their unique magnetic properties, biocompatibility, and versatility. This review comprehensively examines the synthesis methods, surface functionalization techniques, and diverse biomedical applications of IONPs. Various chemical and physical synthesis techniques, including coprecipitation, sol–gel processes, thermal decomposition, hydrothermal synthesis, and sonochemical routes, are discussed in detail, highlighting their advantages and limitations. Surface functionalization strategies, such as ligand exchange, encapsulation, and silanization, are explored to enhance the biocompatibility and functionality of IONPs. Special emphasis is placed on the role of IONPs in biosensing technologies, where their magnetic and optical properties enable significant advancements, including in surface-enhanced Raman scattering (SERS)-based biosensors, fluorescence biosensors, and field-effect transistor (FET) biosensors. The review explores how IONPs enhance sensitivity and selectivity in detecting biomolecules, demonstrating their potential for point-of-care diagnostics. Additionally, biomedical applications such as magnetic resonance imaging (MRI), targeted drug delivery, tissue engineering, and stem cell tracking are discussed. The challenges and future perspectives in the clinical translation of IONPs are also addressed, emphasizing the need for further research to optimize their properties and ensure safety and efficacy in medical applications. This review aims to provide a comprehensive understanding of the current state and future potential of IONPs in both biosensing and broader biomedical fields.

From germolane to germylenes: a theoretical DFT study of thermal decomposition pathways and reactivity

This study addresses the often-overlooked chemistry of germanium compared to the extensively researched carbon and silicon. Using advanced DFT methods, we investigated the thermal decomposition of germolane (germacyclopentane). The suggested mechanisms include a 1,2-H shift and 1,1-H2 elimination to form a pentacyclic germylene (1λ2-germolane). The other pathway involves a stepwise [3 + 2] cycloreversion to form a diradical followed by ethene and germirane. Under M062X/def2-TZVP level of theory, the activation barriers in terms of Gibbs energy (ΔG ‡ 298) for the 1,2-H shift and 1,1-H2 elimination pathways were 240.9 and 236.3 kJ/mol, respectively. The reaction energies (ΔG° 298) for the initiative steps in the 1,2-H shift and 1,1-H2 elimination mechanisms were 102.9 and 96.2 kJ/mol, indicating a thermodynamic and kinetic competition between the two routes. Temperature dependence analysis from 300 to 1200 K reveals that the 1,1-H2 elimination dominates at higher temperatures and is expected to become spontaneous above 1000 K.

Colossal Strain Tuning of Ferroelectric Transitions in KNbO3 Thin Films.

Strong coupling between polarization (P) and strain (ɛ) in ferroelectric complex oxides offers unique opportunities to dramatically tune their properties. Here colossal strain tuning of ferroelectricity in epitaxial KNbO3 thin films grown by sub-oxide molecular beam epitaxy is demonstrated. While bulk KNbO3 exhibits three ferroelectric transitions and a Curie temperature (Tc) of ≈676K, phase-field modeling predicts that a biaxial strain of as little as -0.6% pushes its Tc >975K, its decomposition temperature in air, and for -1.4% strain, to Tc >1325K, its melting point. Furthermore, a strain of -1.5% can stabilize a single phase throughout the entire temperature range of its stability. A combination of temperature-dependent second harmonic generation measurements, synchrotron-based X-ray reciprocal space mapping, ferroelectric measurements, and transmission electron microscopy reveal a single tetragonal phase from 10 K to 975K, an enhancement of ≈46% in the tetragonal phase remanent polarization (Pr),and a ≈200% enhancementin its optical second harmonic generation coefficients over bulk values. These properties in a lead-free system, but with properties comparable or superior to lead-based systems, make it an attractive candidate for applications ranging from high-temperature ferroelectric memory to cryogenic temperature quantum computing.

Spatiotemporal Variation in Mature Source Rocks Linked to the Generation of Various Hydrocarbons in the Fuxin Basin, Northeast China

The assessment of highly mature source rocks linked to hydrocarbon generation remains a challenge in oil and gas exploration. However, substantial terrigenous influences and thermal variations have complicated the formation and evolution of source rocks. This study presents an integrated assessment of highly mature source rocks in the Fuxin Basin, based on sedimentological, geochemical, and organic petrological analyses. Two types of oil- and coal-bearing source rocks were deposited in the semi-deep lake and shore–shallow lake facies during the Jiufotang and Shahai periods. The development of source rocks migrated eastward alongside the lacustrine depocenter, influenced by basin evolution related to extensional detachment tectonism. Furthermore, a gradual increase in thermal records was detected from the western to eastern basins. Consequently, thermal decomposition of source rocks in the Jiufotang formation reduced the organic matter (OM) abundance in the central and eastern basins. Meanwhile, OM types of source rocks range from kerogen type-II1/-I to type-II2/-III, with intense hydrogen generation observed from the western to eastern basins. Consequently, the quality and hydrocarbon accumulation of source rocks are influenced by sedimentation and thermal maturity variation. The spatiotemporal variation in mature source rocks enhances the potential for exploring conventional petroleum, coalbed methane, and shale gas across different strata and locations. Our findings illustrate the significance of the sedimentary and thermal effects in characterizing the evolution of highly mature source rocks, which is relevant to determine oil and gas exploration in similar geological settings.

Study of the Pyrolysis of Ayous and Kambala Co-Products: Kinetic Modeling of the Two Species

A kinetic model based on the two-stage semi-global multi-reaction model of Grioui was developed using the TG and DTG curves for the by-products of Kambala and Ayous. These two tropical species are widely used in the Republic of Congo. The TG and DTG curves were obtained through thermogravimetry at five different heating rates (3, 7, 10, and 20 K/min) up to a final temperature of 800 °C under a nitrogen atmosphere. The thermal decomposition of both species started at similar temperatures, but the profiles exhibited notable differences. Kambala showed a distinct profile with two peaks at approximately 500 °C and 700 °C, which upon further investigation were found to correspond to ash decomposition. Additionally, the shoulder present in Ayous between 250 °C and 300 °C, attributed to hemicelluloses degradation, was absent in the DTG curves for Kambala. The kinetic model for Ayous was formulated in three steps, while the model for Kambala consisted of four steps. Both models accurately predicted the thermal degradation of the wood species, and the resulting kinetic parameters aligned with those reported in the literature.

Effect of Gaseous Atmosphere Composition on the Thermal Decomposition of Calcium Hypophosphite

Effect of Gaseous Atmosphere Composition on the Thermal Decomposition of Calcium Hypophosphite

Features of the Thermal Degradation of Sodium Hyaluronates with Different Molecular Weights

Features of the Thermal Degradation of Sodium Hyaluronates with Different Molecular Weights