Differential Scanning Calorimetry Experiments Research Articles

Rheological Behavior of a New Amorphous Alloy (Al74Cu16Mg10)99,7Zr0.3

A new amorphous alloy (Al74Cu16Mg10)99,7Zr0.3 was prepared the applying a melt-spinning technique. Temperature dependence of viscosity of the alloy was determined using data from a PerkinElmer TMS2 thermo-mechanical analyzer processed according to a methodology based on the Free Volume Model (FVM). The strength of the alloy was calculated according to the Yang equation and the glass-forming ability was calculated according to the values of the Angell index mA. The activation energy of crystallization and the activation energy of the glass transition were computed using data from differential scanning calorimetry and thermomechanical experiments respectively. The activation energy of crystallization Еx = 168 ± 3.7 kJ/mol, was found to be higher than the activation energy of the glass transition Еg = 156 ± 1.4 kJ/mol, which means a dominant contribution of the atomic transport barrier, compared to the nucleation barrier. The relatively high temperature interval of the supercooled melt state Tx-Tg = 32 K and the low viscosity values in the same range ƞ(Тg) = 3.40E + 11 Pa.s and ƞ(Тx) = 1.87E + 10 Pa.s would allow thermomechanical treatment of the alloy in the temperature range of supercooled melt.

Study on structure and viscosity evolution mechanism of titanium-containing iron liquid in full viscosity range

This study aims to investigate the relationship between the viscosity of Fe-4.5wt%C-0.2wt%Ti melt and its liquid structure. The actual experimental results of viscosity measurement reveal that the viscosity range of Fe-4.5wt%C-0.2wt%Ti melt can be segmented into three intervals. Through thermodynamically calculated equilibrium phases and high-temperature confocal experiments, it is observed that the abrupt change in viscosity in the lower temperature range is attributed to the precipitation of the graphite phase. Moreover, differential scanning calorimetry experiments exhibit a distinct phase transition in the liquid phase region. To delve into the atomic structure of the liquid phase region, molecular dynamics simulations are employed. The high-temperature liquid structure of Fe-4.5wt%C-0.2wt%Ti melt predominantly consists of vacancies, atomic clusters with Ti as the core, and atomic clusters with C as the core. Within the high-temperature liquid phase region, the conversion of Free-Fe and C1-Fe to Cx-Fe occurs, resulting in a reduction of free volume and enhanced stability of the cluster. Consequently, the inhomogeneity of the Fe-4.5wt%C-0.2wt%Ti melt increases, and the viscosity exhibits a significant increase with temperature, leading to a variation in the viscosity within the liquid phase interval.

Comprehensive Understanding of the Heavy Oil Combustion Process: Reaction Behavior, Kinetic Triplet, and Mechanism Implication.

In this work, thermo-oxidative behavior, kinetic triplet, and free radical mechanism of ultraheavy oil during an in situ combustion (ISC) process were systematically surveyed via multiple thermal analysis techniques (TG/DTG/DSC/PDSC), model-free methods, and related mathematical simulation. First, specific mass loss, exothermic intensity, and corresponding temperature intervals were respectively determined in low-/high-temperature oxidation (LTO/HTO) regions. In addition, the comparison of atmospheric/pressurized differential scanning calorimetry (DSC/PDSC) experiments indicated that the pressurized conditions could obviously strengthen the oxidation progress with more heat emission. Then two model-free methods were contrastively employed for PDSC data to calculate LTO and HTO activation energy variations with the conversion rate. Moreover, the acceleratory rate model for LTO and the Sestak-Berggren model for HTO were accordingly picked as the most probable mechanism functions, which were later used to determine the simulated curves. Then, the simulations of α-T and dα/dT-T curves were respectively attained using Friedman equation in MATLAB software and contrasted with experimental data to validate the accuracy of the yielded kinetic triplet and forecast the combustion behavior. Further, the evolution pathways of the underlying oxidation mechanism was illustrated. This study updates the understanding of the nonisothermal combustion process, contributing to the subsequent numerical simulation and feasible investigation for in situ combustion implementation to enhance heavy oil recovery.

Near-infrared spectroscopy in resin transfer molding—determination of the degree of cure

Near-infrared (NIR) spectroscopy is employed to directly monitor the degree of cure of composite material during the curing phase in the resin transfer molding (RTM) process. The composite material consists of natural fibers and an epoxy-amine resin system. The quantitative determination of the degree of cure, α, from the NIR spectra is realized by partial least square (PLS) regression in conjunction with various pre-treatments of the spectral data. As a reference, the degree of cure is determined by isothermal differential scanning calorimetry (DSC) experiments. The best PLS model that could be obtained for α is characterized by a determination coefficient of prediction (R²P) of 0.980 and root mean square error of prediction (RMSEP) of 4.4 %. While the spectra change during curing according to the literature for each RTM trial, significant differences can be observed between the spectra of different RTM trials. The reasons for this are discussed in detail. The findings show the potential of inline NIR spectroscopy for monitoring α in the RTM process.

Deciphering the Self-Catalytic Mechanisms of Polymerization and Transesterification in Polybenzoxazine Vitrimers.

The use of internal catalysts has emerged as a pivotal design principle to facilitate dynamic exchanges within covalent adaptable networks (CANs). Polybenzoxazines, specifically, have shown considerable potential in generating vitrimers through thermally induced transesterification reactions catalyzed internally by tertiary amines. This study aims to investigate the chemical complexities of transesterification reactions within benzoxazine vitrimers. To achieve this, model molecules using various phenolic acids and amino-alcohol derivatives were synthesized as precursors. The structure of these model molecules was fully elucidated by using nuclear magnetic resonance (NMR). Differential scanning calorimetry (DSC) and rheology experiments evidenced the accelerated network formation of the precursors due to the presence of aliphatic -OH groups. Thermogravimetric analysis coupled with microcomputed gas chromatography (TGA-μGC) was used to provide evidence of transesterification reactions. The results showed that the spatial proximity between tertiary amine and hydroxyl groups significantly enhances the rate exchange, attributed to a neighboring group participation (NGP) effect. Interestingly, kinetic experiments using complementary NMR techniques revealed the thermal latency of the tertiary amine of benzoxazine toward transesterification reactions as its opening is needed to trigger the dynamic exchange. The study highlights the crucial role of steric hindrance and tertiary amine basicity in promoting the dynamic exchange in an internally catalyzed system.

Preparation and characterization of pH-responsive metal-polyphenol structure coated nanoparticles

In this paper, tannic acid (TA) and Fe3+ were added to form a layer of metal-polyphenol network structure on the surface of the nanoparticles which were fabricated by zein and carbon quantum dots (CQDs) encapsulating phlorotannins (PTN). pH-responsive nanoparticles were prepared successfully (zein-PTN-CQDs-FeIII). Further, the formation of composite nanoparticles was confirmed by a series of characterization methods. The zeta-potential and Fourier transform infrared spectroscopy data proved that electrostatic interaction and hydrogen bonding are dominant forces to form nanoparticles. The encapsulation efficiency (EE) revealed that metal-polyphenol network structure could improve the EE of PTN. Thermogravimetric analysis and differential scanning calorimetry experiment indicated the thermal stability of zein-PTN-CQDs-FeIII nanoparticles increased because of metal-polyphenol network structure. The pH-responsive nanoparticles greatly increased the release rate of active substances and achieved targeted release.

CYP116B5-SOX: An artificial peroxygenase for drug metabolites production and bioremediation.

CYP116B5 is a class VII P450 in which the heme domain is linked to a FMN and 2Fe2S-binding reductase. Our laboratory has proved that the CYP116B5 heme domain (CYP116B5-hd) is capable of catalyzing the oxidation of substrates using H2O2. Recently, the Molecular Lego approach was applied to join the heme domain of CYP116B5 to sarcosine oxidase (SOX), which provides H2O2 in-situ by the sarcosine oxidation. In this work, the chimeric self-sufficient fusion enzyme CYP116B5-SOX was heterologously expressed, purified, and characterized for its functionality by absorbance and fluorescence spectroscopy. Differential scanning calorimetry (DSC) experiments revealed a TM of 48.4 ± 0.04 and 58.3 ± 0.02°C and a enthalpy value of 175,500 ± 1850 and 120,500 ± 1350 cal mol-1 for the CYP116B5 and SOX domains respectively. The fusion enzyme showed an outstanding chemical stability in presence of up to 200 mM sarcosine or 5 mM H2O2 (4.4 ± 0.8 and 11.0 ± 2.6% heme leakage respectively). Thanks to the in-situ H2O2 generation, an improved kcat/KM for the p-nitrophenol conversion was observed (kcat of 20.1 ± 0.6 min-1 and KM of 0.23 ± 0.03 mM), corresponding to 4 times the kcat/KM of the CYP116B5-hd. The aim of this work is the development of an engineered biocatalyst to be exploited in bioremediation. In order to tackle this challenge, an E. coli strain expressing CYP116B5-SOX was employed to exploit this biocatalyst for the oxidation of the wastewater contaminating-drug tamoxifen. Data show a 12-fold increase in tamoxifen N-oxide production-herein detected for the first time as CYP116B5 metabolite-compared to the direct H2O2 supply, equal to the 25% of the total drug conversion.

Unraveling the characteristics and pyrolysis mechanism of diethylene glycol dinitrate plasticized nitrocellulose supplemented with organic stabilizers

The current work examined the properties and thermal decomposition mechanism of a double-base propellant comprising nitrocellulose (NC), diethylene glycol dinitrate (DEGDN), and organic stabilizers. To achieve this objective, a comprehensive analysis was conducted on the influence of stabilizers, namely 2-nitrodiphenylamine (2-NDPA), 1,3-dimethyl-1,3-diphenylurea (MC), and kraft lignin, on the characteristics and pyrolysis gases of NC/DEGDN. Experimental findings demonstrated that kraft lignin has a good stabilizing efficiency, similar to that of 2-NDPA and MC stabilizers. Moreover, differential scanning calorimetry (DSC) experiments revealed that the incorporation of MC, 2-NDPA, and Kraft lignin has increased the maximum peak temperature of the main thermolysis process from Tpeak = 192.1 °C for NC/DEGDN baseline to Tpeak = 194.5 °C for NC/DEGDN/MC, Tpeak = 193.3 °C for NC/DEGDN/2-NDPA, and Tpeak = 194.3 °C for NC/DEGDN/Kraft lignin. In addition, differences in the stabilization mechanism for each stabilizer were examined using thermogravimetry connected to an infrared spectroscopy (TGA-FTIR). The obtained findings highlighted the discernible influence of stabilizer types on the gaseous products of NC/DEGDN propellant, particularly elucidating their effects on the intensity and type of nitrogen oxides generated throughout the pyrolysis process.

Tracing the phase formation and stability of the clathrate phase BaGe5

Thermal stability and phase formation of the clathrate phase BaGe5 and its formation from the clathrate-I phase Ba8Ge43□3 (□ = vacancy in the crystal structure) have been investigated by microstructure analysis, differential scanning calorimetry (DSC), and powder X-ray diffraction (PXRD). The experiments confirm the peritectic formation of the high-temperature phase Ba8Ge43□3 from α-Ge and liquid at 810 °C, and the eutectic temperature of Ba8Ge43□3 and Ba6Ge25 at 808 °C. At T = 770 °C, Ba8Ge43□3 decomposes by a eutectoid reaction to Ba6Ge25 and α-Ge, and at T = 520 °C, the low-temperature phase BaGe5 forms in a peritectoid reaction from these two phases. BaGe5 was synthesized by decomposition of the high-temperature clathrate-I phase Ba8Ge43□3 at temperatures between 350 °C and 520 °C. Annealing and DSC experiments verify that BaGe5 is an equilibrium phase at ambient pressure. The formation of BaGe5 from Ba8Ge43□3 was traced through microstructure analysis, revealing microdomains with pleochroic behavior in polarized light.

Environmental fatigue crack growth of PV glass/EVA laminates in the melting range

AbstractThe delamination of encapsulants in photovoltaic (PV) modules is a common issue that leads to power loss due to optical losses. Encapsulant debonding is usually examined under monotonic loading conditions subsequent to environmental exposure such as damp heat. Service‐relevant, superimposed environmental‐mechanical fatigue loads are not considered adequately. Hence, the environmental fatigue delamination resistance of thermally toughened double glass laminates with an ethylene vinyl acetate copolymer (EVA) adhesive layer was investigated in this study. Focus was given to the melting range of EVA, in which the non‐crosslinked crystalline phase fraction is already in the partly molten state. Double cantilever beam specimens were tested on an electrodynamic test machine at temperatures of 60, 70, 80, and 90°C and relative humidity (rh) levels of 2%, 30%, 50%, and 80%. The fractured surfaces were characterized by digital microscopy, Fourier transform infrared spectroscopy (FTIR), X‐ray photoelectron spectroscopy (XPS), and differential scanning calorimetry (DSC). The cyclic fatigue tests revealed a decay in delamination resistance at elevated temperature and humidity levels. At 70°C, the delamination resistance was low, regardless of the relative humidity. Most of the laminates failed by debonding. XPS analysis showed a reduction of the C=O and C–O content, along with an increase in Si–O content with increasing relative humidity. For laminates tested at 60 and 70°C, an EVA recrystallization peak was observed in DSC experiments. This peak was shifted to significantly higher temperatures at 80% rh. XPS and DSC indicated local hydrolysis within the porous fracture process zone ahead of the crack tip. Consequently, acetic acid formation led to a decrease in delamination resistance, resulting in lower fatigue threshold values. The investigations confirmed the significant impact of environmental conditions on the fatigue delamination resistance within glass/encapsulant laminates. Notably, acetic acid formation and a significant reduction in delamination properties were observed after around 100 h of environmental fatigue exposure.

Complexity of the KNa2ZrF7, KNa2HfF7, and KNa2(Hf,Zr)F7 compounds

New mixed-cation fluorides KNa2HfF7 (Pmn21, a = 8.213(2) Å, b = 6.126(2) Å, c = 5.979(2) Å, Z = 2) and KNa2(Hf,Zr)F7 (refined composition KNa2Hf0.44(1)Zr0.56(1)F7; Pmn21, a = 8.2210(8) Å, b = 6.1288(6) Å, c = 5.979(1) Å, Z = 2) together with isostructural KNa2ZrF7 (Pmn21, a = 8.221(2) Å, b = 6.118(2) Å, c = 5.994(2) Å, Z = 2) have been synthesised in aqueous solutions and structurally characterised at room temperature by powder and single-crystal X-ray diffraction. The solid-solid phase transformations have been revealed during the differential scanning calorimetry experiments and further confirmed by temperature-dependent X-ray powder diffraction. It has been found that mixed-cation phases KNa2ZrF7, KNa2HfF7 and KNa2(Hf,Zr)F7 undergo irreversible phase transformations, which can be explained by their decomposition over 673 K. XPS analysis confirmed the presence of exclusively terminated fluorines around the transition metals and the absence of oxygen impurities in the crystal structures of compounds.

Calorimetric and kinetic evaluation of thermal stability and process safety in tert-butyl peroxy-2-ethylhexanoate and tert-butyl peroxybenzoate

This study evaluated the thermal stability and process safety of tert-butyl peroxybenzoate (TBPB), tert-butyl peroxy-2-ethylhexanoate (TBPO), and their mixture. Thermogravimetric (TG) analysis, differential scanning calorimetry (DSC), and accelerated rate calorimetry were used to elucidate the thermal behavior and breakdown kinetics. The TG results indicated moderate to low breakdown temperatures for all samples, demonstrating their thermal stability. DSC revealed onset temperatures for exothermic disintegration between 66.66 °C and 104.23 °C. The mixture had two distinct exothermic peaks, signifying the thermal decomposition of the mixture was such that the characteristic temperature and heat of the reaction were between those of TBPB and TBPO. Using Heat–Wait–Search methodology, the study identified thermal runaway exothermically. Under pseudoadiabatic conditions, the mixture exhibited greater increases in temperature and pressure—of 115.06 °C and 28.77 bar, respectively—compared with the individual compounds. To elucidate the apparent activation energy (Ea) and reaction kinetics, the study applied models developed by Arrhenius, Flynn-Wall-Ozawa, Friedman, Kissinger, and Starink. The Ea values obtained based on the TG, DSC, and ARC experiments were approximately 50.47, 98.19, and 99.71 kJ/mol, respectively, and were lower than those of TBPB and TBPO pure substances. The self-accelerating decomposition temperature of TBPB/TBPO decreased from 34 to 32 °C as the packaging of TBPB/TBPO was increased from 25 to 100 kg and was more than 10 °C lower than that of the individual substance. These findings offer a framework for evaluating the thermal risks associated with TBPB and TBPO, particularly when mixed. They contribute to the safe transit, storage, and handling of industrial organic peroxides, enriching our collective understanding of the stability and safety of these compounds.

Improving barrier properties of polyethylene/Fe2O3‐modified nanographene nanocomposites in a magnetic field

AbstractThe present work aims at improving the barrier properties of high molecular weight Polyethylene/ graphene nanoplatelets (HMWPE/GnP) nanocomposites by aligning the embedded modified graphene nanoparticles in a magnetic field. Graphene nanoplatelets (GnP) were modified by magnetic Fe2O3 to produce Fe2O3‐modified Graphene, GnP‐mFe2O3. The magnetic properties of Fe2O3 were previously characterized by the vibrating sample magnetometer (VSM) method and resulting GnP‐mFe2O3 nanoparticles were characterized by Fourier transform infrared (FTIR) analysis. HMWPE/GnP nanocomposites were prepared via melt mixing. The prepared nanocomposites were sheeted at high temperatures in a magnetic field using a hot press. The barrier properties of prepared films, HMWPE/GnP and HMWPE/GnP‐mFe2O3 were characterized by carrying out a permeation to oxygen experiment as a function of GnP and GnP‐mFe2O3 contents. A decrease in gas transmission rate (GTR) was observed for the samples after being subjected to the magnetic field compared to the non‐treated sample. The results of differential scanning calorimetry (DSC) and field emission electron microscopy (FESEM) experiments confirmed the orientation of GnP‐mFe2O3 nanoparticles in nanocomposites.

Probing the binding and interaction of curcumin-tryptophan conjugate to G-quadruplex motif via spectroscopic and molecular docking approach

A potential ligand with the ability to interact with the structure of G-quadruplexes has been promising strategy for develop anticancer drug. Curcumin, a natural antioxidant is known to induce apoptosis in the tumour cells and was previously found as G-quadruplex binder. We investigated how the conjugation of tryptophan with curcumin affects its ability as G-quadruplex DNA binder. We have reported the differential interaction of Curcumin-tryptophan (CT) with a parallel G-quadruplex(GQ) formed by the nuclease hypersensitivity element (NHEIII) Pu27 present of the protooncogene and human telomeric G-quadruplex sequence. Taken into account, ligand CT has a stronger binding affinity for the G-quadruplex over the canonical duplex DNA. We have used biophysical approach such as uv-visible, fluorescence, circular dichroism, differential scanning calorimetry and molecular docking experiment to show that curcumin tryptophan interacts with the G-quadruplex. The results indicate that CT has a binding affinity of 106 M−1 for G-quadruplexes. Thermodynamic studies show that the ligand CT destabilizes the G-quadruplexes (6–8 °C) due to aromatic core stacking between the tetrad. The anti-proliferative experiment of the synthesized ligand CT in vitro on several cancer cell lines such as HeLa cells and MCF-7 cell lines shows that it is more effective against MCF-7. Thus, present studies report Curcumin-tryptophan as a potential G-quadruplex binder that destabilizes the quadruplex structure .

Crystal structure analysis of the adduct 1:1 hexamethylenetetramine and succinic acid (HMT−C4) as a function of the temperature

Co−crystals of hexamethylenetetramine [N4(CH2)6, (HMT)] and dicarboxylic acids of general formula HOOC(CH2)n−2COOH with 4 ≤ n ≤ 14 (Cn), called HMT−Cn, exhibits structural properties strongly dependent on the length of the dicarboxylic acid chain, showing a wide variety of thermotropic phase transition sequence. This study focuses on describing the structural features of the HMT−C4 (1:1) adduct, a co-crystal of HMT and succinic acid (C4), exhibiting a reversible first-order phase transition at 222(4)K, as evidenced by differential scanning calorimetry (DSC) experiments. In contrast to a prior investigations , which did not identify this phase transition, our comprehensive temperature-dependent analysis, incorporating single crystal X-ray diffraction and DSC experiments, reveals a reversible structural change in the HMT−C4 (1:1) adduct structure upon cooling and heating. The crystal structures of the different observed phases are discussed in detail, emphasizing the role of O−H···N intermolecular hydrogen bonds in maintaining the connectivity between HMT and C4 molecules. The observed phase transition involves doubling the unit cell volume and significant reorientation of the −COOH groups at the end of the C4 chain at around 222(4)K. Our findings underscore the importance of additional temperature-dependent experiments, such as DSC, in avoiding erroneous structure modeling due to symmetry changes during temperature variations. The preservation of the acidic character of the C4 dicarboxylic chain throughout the temperature range adds additional insights to the understanding of the structural behavior of all the HMT−Cn (1:1) adducts.

Phase-equilibrium characteristics of methane hydrate in clay mineral suspensions: Differential scanning calorimetry experiments and density functional theory studies

The investigation of methane hydrate equilibrium conditions is crucial for comprehending the occurrence of methane hydrate in marine sediments. In this study, the liquid-hydrate-vapor equilibrium condition of methane hydrate in montmorillonite and kaolinite suspensions in the presence of glycine was investigated through differential scanning calorimetry experiments. The results indicated that glycine inhibited the phase equilibrium of methane hydrate. The phase equilibrium conditions of methane hydrate in kaolinite suspension closely resembled those in pure water. In contrast, calcium montmorillonite hindered the phase equilibrium of methane hydrate owing to the presence of Ca2+. The phase equilibrium conditions of methane hydrate in kaolinite suspension with the addition of glycine were similar to those in glycine solution. The inhibitory effect of calcium montmorillonite on the phase equilibrium condition of methane hydrate intensified with the addition of glycine. Furthermore, density functional theory simulations indicated that glycine significantly reduced the binding energy between montmorillonite layers and Ca2+, potentially mitigating the inhibitory effect of Ca2+ on methane hydrate formation under suitable glycine concentrations. The diverse equilibrium conditions of methane hydrate, influenced by the types of clay minerals, salt ions, and organic matters, may play a critical role in the formation and occurrence of natural gas hydrates in marine environments, warranting exploration in future studies.

Synergetic Effect of FeTi in Enhancing the Hydrogen-Storage Kinetics of Nanocrystalline MgH2

High-energy ball milling was applied to produce nanocrystalline MgH2-FeTi powder composites. In order to achieve a remarkable synergetic effect between the two materials, the amount of the FeTi catalyst was chosen to be 40 wt.%, 50 wt.% and 60 wt.%. The morphology and microstructure of the as-milled powders were characterized by scanning electron microscopy and X-ray diffraction, respectively. The evaluation of the diffraction profiles by the Convolutional Multiple Whole Profile fitting algorithm provided a detailed microstructural characterization of the coherently scattering α-MgH2 crystallites. Differential scanning calorimetry experiments revealed two overlapping endotherms corresponding to the dehydrogenation of metastable γ-MgH2 and stable α-MgH2 hydrides. Isothermal hydrogen-sorption experiments were carried out in a Sieverts-type apparatus. It was established that the MgH2-40 wt.% FeTi powder is capable of absorbing 5.8 wt.% hydrogen, while extraordinary absorption kinetics were observed for the MgH2-50 wt.% FeTi alloy, i.e., 3.3 wt.% H2 is absorbed after 100 s.

Sustainable treatment and recycling of oily sludge: Incorporation into gel -system to improve oil recovery.

Oily sludge is very difficult to treat in solid waste, how to achieve on-site treatment and recycling of the sludge is rarely reported. This research proposes a new treatment method for oily sludge by adding the oily sludge into the gel water plugging system designed for low-performing oilfields-sludge re-injection technology. The gel system of oily sludge can resist dehydration for 150 days at a high temperature up to 140 °C and a salinity of 2.11 × 105 mg/L, and its strength reaches grade I. The microstructure of the gel was revealed using scanning electron microscopy (SEM). The addition of oily sludge made the gel system microstructure develop a dense three-dimensional network structure, which can effectively improve the strength and temperature resistance of the gel system. Differential scanning calorimetry (DSC) experiments show that the gel with oily sludge can maintain temperature resistance even at 188 °C. Laboratory displacement experiments show that the breakthrough pressure of the gel system can reach 3418 kPa/m, and the plugging rate is above 98%. The performance of the system was improved by adding oily sludge into the gel as an enhancer, which provided a research idea for harmless treatment, resource utilization and clean production of oily sludge.

TATB thermal decomposition: An improved kinetic model for explosive safety analysis

AbstractWe investigate and model the cook‐off behavior of 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB) to understand the response of explosive systems in abnormal thermal environments. Decomposition has been explored via conventional ODTX (one‐dimensional time‐to‐explosion), PODTX (ODTX with pressure‐measurement), PyGC‐MS (pyrolysis gas chromatography mass spectrometry), TGA (thermo‐gravimetric analysis), DSC (differential scanning calorimetry), and IR (infrared spectroscopy) experiments under isothermal and ramped temperature profiles. The data were used to fit rate parameters for proposed reaction schemes in a MATLAB thermo‐chemical computational model. These parameterizations were carried out utilizing a genetic algorithm optimization method on LLNL's high‐performance computing clusters, which enabled significant parallelization. These results include a multi‐step reaction decomposition model, identification of likely autocatalytic gas‐phase species, accurate high‐temperature sensitization, and prediction of confined system pressurization. This model will be scalable to several applications involving TATB‐based explosives, like LX‐17, including thermal safety models of full‐scale systems.

Development of porous asphalt mixture based on the synthesis of PTEMG and MDI polyurethane asphalt

Polyurethane-modified asphalt (PA) stands out as an environmentally sustainable road material, renowned for its exceptional performance that significantly extends road surface lifespans while reducing maintenance costs. This study focuses on the preparation of PA using a single-component blending method that incorporates polyether polyol PTEMG (Poly-(tetra methylene ether glycol)) and isocyanate MDI (4,4′-diphenylmethane diisocyanate) as primary raw materials. Various analytical techniques, including Fluorescence Microscopy, Fourier-transform Infrared Spectroscopy (FTIR), Thermogravimetric analysis (TG), Differential Scanning Calorimetry (DSC), Viscosity Testing, Tensile Testing, and Bending Beam Rheometer (BBR), were employed to investigate PA's microstructure, modification mechanism, thermal properties, viscosity characteristics, curing properties, and low-temperature stability. A porous polyurethane-modified asphalt mixture, targeting a void content of 20%, was designed and compared to a high-viscosity modified asphalt mixture with the same void content in terms of performance. The results indicate a combination of chemical and physical processes in PA modification. Through TG and DSC experiments, it was ascertained that polyurethane-modified asphalt commences decomposition at 252 °C, exhibiting an exothermic peak within the temperature range of − 19.98–2.73 °C. The introduction of polyurethane substantially enhances the thermal performance and cryogenic stability of the asphalt binder. Viscosity tests and tensile experiments indicate that the curing reaction of polyurethane-modified asphalt is protracted and irreversible. Consequently, it is recommended to prepare polyurethane-modified asphalt mixtures employing a compaction temperature of 175 °C and a maximum resting time of 100 min. Additionally, specimens should rest at room temperature for at least 3 days. Comparatively, the porous asphalt incorporating polyurethane exhibits notable advantages over the high-viscosity modified asphalt mixture. It demonstrates superior high-temperature stability, excellent resistance to low-temperature cracking, reduced sensitivity to strains, prolonged fatigue life, and improved flexibility. However, its fatigue resistance and resistance to dynamic loads are slightly inferior. This study offers valuable insights into the use of polyurethane in porous asphalt mixtures, making it a promising option for sustainable road construction.