Low-temperature Decomposition Research Articles

Impact of Thermal Treatment and Aging on Lignin Properties in Spruce Wood: Pathways to Value-Added Applications.

Thermal modification is an environmentally friendly process that does not utilize chemical agents to enhance the stability and durability of wood. The use of thermally modified wood results in a significantly extended lifespan compared with untreated wood, with minimal maintenance requirements, thereby reducing the carbon footprint. This study examines the impact of varying modification temperatures (160, 180, and 210 °C) on the lignin of spruce wood using the ThermoWood process and following the accelerated aging of thermally modified wood. Wet chemistry methods, including nitrobenzene oxidation (NBO), size exclusion chromatography (SEC), thermogravimetry (TG), differential thermogravimetry (DTG), and Fourier transform infrared spectroscopy (FTIR), were employed to investigate the alterations in lignin. At lower modification temperatures, the predominant reaction is the degradation of lignin, which results in a reduction in the molecular weight and an enhanced yield of NBO (vanillin and vanillic acid) products. At elevated temperatures, condensation and repolymerization reactions become the dominant processes, increasing these traits. The lignin content of aged wood is higher than that of thermally modified wood, which has a lower molecular weight and a lower decomposition temperature. The results demonstrate that lignin isolated from thermally modified wood at the end of its life cycle is a promising feedstock for carbon-based materials and the production of a variety of aromatic monomers, including phenols, aromatic aldehydes and acids, and benzene derivatives.

The Integration of Microwave-Synthesized Silver Colloidal Nanoparticles into Poly (Lactic Acid)-Based Textiles as Antimicrobial Agents via Pre- and Post-Electrospinning Processes.

This study introduces a novel method to enhance the antibacterial functionality of electrospun nanofibrous textiles by integrating silver nanoparticles (AgNPs) into poly (lactic acid) (PLA) fabrics through pre- and post-electrospinning techniques. AgNPs were incorporated into hydrophobic and modified hydrophilic PLA textiles via pre-solution blending and post-solution casting. A PEG-PPG-PEG tri-block copolymer was utilized to enhance hydrophilicity and water stability, while AgNPs served as antibacterial agents. Morphological analyses confirmed uniform, smooth, and beadless nanofibers with diameters between 435 and 823 nm. Energy-dispersive X-ray spectroscopy spectra and elemental analysis verified the successful incorporation of AgNPs, with higher Ag content in the post-electrospinning samples. Contact angle measurements showed an improved hydrophilicity of the modified PLA textiles, absorbing water droplets within 2 s. The X-ray crystallography patterns confirmed the amorphous structures of the PLA and PEG-PPG-PEG, with reduced crystallinity in the samples containing AgNPs. Thermal analysis indicated lower decomposition temperatures for the hydrophilic samples due to the plasticizing effects of PEG-PPG-PEG on PLA. Mechanical testing showed comparable tensile strengths but reduced elongation in the post-treated samples. The antibacterial efficacy was assessed against various bacterial strains, with post-electrospinning AgNP incorporation showing the most effective antibacterial properties. The results indicate that integrating electrospinning and nanofiber modification techniques expands the applications of PLA-based protective fabrics for disabled individuals.

A novel approach of using SiC for the reductive decomposition of industrial by‐product gypsum

AbstractIn this study, thermodynamic calculations indicate that using silicon carbide (SiC) as an additive for the reductive decomposition of industrial by‐product (IBP) gypsum is a feasible method to lower decomposition temperature and avoid the generation of liquid phase. Experimental results show that the decomposition rate of IBP gypsum exceeded 90% at 950°C for 2 h, while avoiding the generation of liquid phase. In addition, it was found that an intermediate product, 2Ca2SiO4·CaSO4, was generated during the decomposition process. Through the reaction mechanism and kinetics analysis of IBP gypsum and SiC, the decomposition process can be divided into two steps. The first step was the conversion of CaSO4 to 2Ca2SiO4·CaSO4 (decomposition rate <60%), and the chemical reaction was the controlling step. The second stage was the conversion of 2Ca2SiO4·CaSO4 to Ca2SiO4 (decomposition rate >60%), and three‐dimensional diffusion was the controlling step. This novel method not only successfully lowered the decomposition temperature of IBP gypsum, but also avoided liquid phase generation.

Facile Preparation of Ultrafine Porous Copper Powders for Accelerating the Thermal Decomposition of Ammonium Perchlorate.

In this study, we innovatively proposed a facile method to synthesize ultrafine porous copper (Cu) powders under mild conditions by utilizing the reduction properties of reduced iron (Fe) powders. The results showed that Cu2+ was easily reduced to Cu at 1.05-1.1 times the theoretical iron powder content for a reaction time of 10~20 min at 20~25 °C. The obtained Cu powders with an average diameter of 10.2 μm did not show significant differences in crystal structure and purity compared to the commercial Cu powders with an average diameter of 6.6 μm, but the prepared Cu powders showed a loose and porous structure, which demonstrates their higher potential in catalyzing energetic materials. The ultrafine porous Cu powder resulted in a significant decrease in the high decomposition temperature of ammonium perchlorate (AP) from 441.3 °C to 364.2 °C at only 1% of the dosage, and also slightly advanced its low decomposition temperature, which confirmed its remarkable catalytic activity in the field of energetic materials. These meaningful results will provide a new method for the preparation of Cu powders and promote the development of the chemical reduction method for the preparation of ultrafine porous Cu powders, which is expected to promote the application of ultrafine porous Cu powders in the field of energetic materials catalysis.

Comprehensive revelation of the influence mechanism for the thermal decomposition of ammonium perchlorate by ammonium oxalate

Rate inhibitors for combustion are crucial to decrease the burning rate and prolong the working time of solid propellants. Ammonium oxalate (AO), the most frequently utilized and effective rate inhibitor in propellants, faces the challenge of an unclear influence mechanism regarding ammonium perchlorate (AP). Therefore, it is necessary to elucidate the influence mechanism of AO on the thermal decomposition of AP. This study fabricated AP/AO composites with varying AO content via wet milling, the structural, thermal decomposition processes and products of these composites were investigated. Additionally, the adsorption between AP and NH3 was simulated. The findings indicate that the inclusion of AO inhibits the low-temperature decomposition (LTD) of AP while enhancing its high-temperature decomposition (HTD). Furthermore, it was observed that the heat release of AP/AO composites was lower than that of AP. The Gibbs free energy (ΔG≠) of the AP/AO composites exceeded that of the AP at the LTD stage and was lower than that of AP at the HTD stage. Further study using molecular dynamics simulations revealed that as the increase of NH3 concentration, its adsorption on the AP surface intensifies during LTD, inhibiting the forward progress of the AP decomposition reaction. However, NH3 molecules desorbed from the AP surface and actively participated in gas-phase reactions with increasing temperature, thereby promoting the HTD of AP. This work is helpful to fully understanding the mechanism of AO in the process of the LTD and the HTD of AP but also contributes to the exploration of novel inhibitors and advances the development of low-burning rate solid propellants.

Thermal decomposition and shock response mechanism of DNTF: Deep potential molecular dynamics simulations

A neural network deep potential (DP) is developed for the shock response and thermal decomposition mechanisms of 3,4-Bis(3-nitrofurazan-4-yl)furoxan (DNTF). This DP potential, trained on ab initio datasets, achieves the accuracy of density functional theory (DFT) and higher computational efficiency. The simulation results show that DNTF is anisotropic under shock loading. And the critical shock decomposition temperatures along the [100], [010], and [001] directions are 463.64 K, 451.85 K, and 486.69 K, respectively. For the first time, the low-temperature (<750 K) decomposition of DNTF is successfully simulated using molecular dynamics combined with DP model. The decomposition of DNTF begins with the O-N bond opening of the furoxan ring, followed by the breaking of the C-NO2 bond and opening of the furazan rings, under thermal conditions. The critical thermal decomposition is between 458.3 K and 562.5 K at a heating rate of 13.5 K/ps. The final products are CO2, N2, and CO, and the main intermediates are NO2, NO, and N2O. The activation energy of decomposition is 142.4 kJ/mol obtained by Ozawa method. This study not only provides a powerful tool for investigating the performance of DNTF but also offers a feasible approach for other energetic materials, advancing the field significantly.

MoS2 stabilize Ti3C2 MXene for excellent catalytic effect of thermal decomposition of ammonium perchlorate

Ammonium perchlorate (AP), the most widely used oxidizer in energetic materials, is crucial for studying catalytic thermal decomposition. Newly discovered Ti3C2 MXene and MoS2 demonstrating promising prospects in the field of the pyrolysis catalyst in AP. In this study, we employed a hydrothermal method to anchor nano-sized MoS2 in situ on the surface of Ti3C2 MXene, leading to the fabrication of MoS2-Ti3C2 nanocomposites. Various characterizations indicated that MoS2 was attached to the surface and edges of Ti3C2, thereby enhancing the stability and conductivity. Results revealed that upon the addition of 4 wt% MoS2-Ti3C2, the low-temperature decomposition peak of AP reduced from 331.2 °C to 296.6 °C, while the high-temperature decomposition peak advanced from 427.5 °C to 387.1 °C, showing a superior catalytic effect compared to the individual MoS2 or Ti3C2. Additionally, the catalytic mechanism of MoS2-Ti3C2 on the thermal decomposition of AP may involve enhanced electrical conductivity, facilitating rapid proton transfer (H+), accelerated redox reactions, prompt release of gas products, and thereby expediting the progression of the decomposition reaction. Consequently, it can be anticipated that anchoring MoS2 on the surface of Ti3C2 represents an effective strategy for enhancing the catalytic activity of Ti3C2 MXene towards the thermal decomposition of AP.

Regularities of decomposition of metastable phases in titanium pseudo-β-alloys

The results of a study of metastable phase decomposition in a titanium pseudo-β-alloy are presented. The paper considers main patterns of evolution of the structure and phase composition of a high-alloy titanium grades with a thermally unstable β-phase depending on the heat treatment mode. The influence of the isothermal holding temperature on the morphology and degree of recrystallization of the precipitating phase is shown. The results of the study indicate that low-temperature decomposition of the metastable β-phase in the alloy leads to its embrittlement.

Synergetic effect of Fe decorated MnO2 nanocatalyst application in propane and benzyl alcohol oxidation

In heterogeneous catalysis, one of the key challenges is to develop inexpensive and abundant materials. Herein, spherically shaped α–Fe2O3 nanoparticles decorated over MnO2 nanorods surface (Fe/MnO2NRs) was synthesized via hydrothermal followed by co–precipitation methods. Experimental results indicated that the inclusion of Fe in MnO2NRs promotes a strong interaction that increases the reducibility of Mn4+ to Mn3+ and surface adsorbed oxygen (Oads.), which in turn increases the activation of surface oxygen on MnO2NRs. The 10 wt% Fe–loaded catalyst (10Fe/MnO2NRs) exhibited the highest catalytic activity. It was observed that oxidizing 10 % (T10), 50 % (T50), and 90 % (T90) of propane required temperatures of 140 °C, 180 °C, and 220 °C, respectively. This catalyst showed stability in H2O atmospheres and apparent activation energy as low as 52.54 kJ mol−1. In addition, the vapour phase oxidation of benzyl alcohol (BnOH) over different Fe–loaded MnO2NRs catalysts is investigated. The rate of BnOH oxidation over 10Fe/MnO2NRs catalyst is 1.71 times greater than bare MnO2NRs at 240 °C. The increased oxygen vacancies can improve the oxidation activity of propane and BnOH by facilitating the adsorption and activation of O2 to produce reactive oxygen species. This work offers a novel approach to increase manganese oxides surface oxygen activity, which can be used to create efficient catalysts for the low–temperature decomposition of volatile organic compounds (VOCs) and other organic functional group transformations via oxidation reaction.

Thermal decomposition temperature-dependent bonding performance of Ag nanostructures derived from metal–organic decomposition

In wide-bandgap semiconductor power device packaging, die bonding refers to attaching the die to substrate. Thereby, the process temperature of Ag sintering for the die bonding should be low to prevent damage to fragile dies. Herein, an organic-free strategy using Ag nanostructures derived from the thermal decomposition of metal–organic decomposition (MOD) was proposed to achieve low-temperature bonding. Significant effects on bonding performance were determined by the thermal decomposition temperature, which in turn determined the organic content and sintering degree of Ag nanostructures. At a low thermal decomposition temperature of 160 °C, incomplete decomposition resulted in high organic content in the Ag nanostructures, causing large pores inside the Ag joints owing to the generation of gaseous products. Owing to the Ag particles with naked surfaces and wide size distribution, the Ag nanostructure obtained at 180 °C showed an excellent bonding performance, resulting in a high shear strength of 31.1 MPa at a low bonding temperature of 160 °C. As the thermal decomposition temperature was 200 °C, sintering among Ag particles increased the particle size, resulting in a reduction of surface energy and driving force for sintering. We think that uncovering this underlying mechanism responsible for the bonding performance will promote the application of Ag MOD in the die bonding of WBG power devices.Graphical abstract

Experimental and numerical study on the suppression of brown coal explosion characteristics by different types of solid explosion suppressants

A 20L spherical explosion testing system was used to characterize the explosion characteristics of brown coal powder and its mixing with different explosion suppressants. and the free radical reaction mechanism was studied through numerical simulation. Research has shown that sodium bicarbonate (NaHCO3) has a low decomposition temperature and a fast reaction rate in the early stages. A significant amount of phosphorous groups are produced when ammonium dihydrogen phosphate (NH4H2PO4) and melamine polyphosphate (MPP) react, consumes explosive free radicals and blocks heat transmission between coal dust, delaying and inhibiting explosion. In the explosive reaction, H and O free radicals are continually consumed during the breakdown of cyanuric acid melamine (MCA). Finally, the suppression mechanism of different explosion suppressants on coal powder explosions was revealed, and specific recommendations were made for the selection and application of explosive suppressants.

A Study on the Application of Lining Adhesives to Canvas Reinforcement Treatment(Patching)

Canvas patching utilizes various adhesives for localized reinforcement treatment, yet evaluations of their properties remain insufficient. This study presents surface changes and physical properties observed when seven types of lining adhesives, selected from prior research, were applied. Evaluations included contact angles, color changes, surface alterations, and tensile strength. Results indicated that glue paste was highly susceptible to moisture and exhibited decreased flexibility with environmental changes, while Beva film showed the most significant reduction in adhesion. Both glue paste and Beva film were sensitive to color changes, primarily displaying yellowing and browning. Plextol B500 demonstrated the greatest increase in adhesion and flexibility under environmental stress. Welding powder exhibited high adhesion but lower strain rates, causing notable deformations across the canvas. Within the same adhesive composition, higher hydrophilicity correlated with reduced yield stress and maximum strain, suggesting that hydrophilicity affects adhesion and flexibility. Adhesives with lower thermal decomposition and glass transition temperatures experienced greater changes in adhesion and flexibility. Rapid changes in adhesion following localized reinforcement treatment can lead to issues like peeling of reinforcing fabric or deformation of the canvas.

Crystallization-Based Modification of Ammonium Perchlorate Heat Release.

Composite propellants use the decomposition of crystalline oxidizers, such as ammonium perchlorate (AP), to produce oxidizing species that can combust with fuels. Controlled crystal microstructure must be leveraged to tailor reactivity to minimize the use of exotic energetic materials. This work uses meniscus-guided coating (MGC) to fabricate films of AP with a high degree of control over the AP crystal microstructure. Exploring a wide range of crystallization parameters resulted in film thickness ranging from 200 nm to 14 μm, particle size ranging from 18 to 110 μm, variable preferential orientation with respect to the substrate, and relative defect density ranging from 2.74 × 105 to 6.78 × 105 μm-3. Increasing coating blade speed and substrate temperature within the MGC process shifts the preferential orientation of the AP crystals from predominantly exhibiting (002) and (210) crystal planes parallel to the substrate to (200)/(011) crystal planes parallel to the substrate. This shift in orientation is accompanied by an increase in defect density, which is shown to increase the heat release from the low-temperature decomposition regime and decrease the heat release from the high temperature regime. These results demonstrate the ability to use recrystallization, defect density control, and orientation control to tune the heat release profiles of energetic materials to augment propellant performance.

Dissolution of denim waste in N-methyl morpholine-N-oxide monohydrate for fabrication of regenerated cellulosic film: Experimental and simulation study

Despite the significant amount of denim waste and its potential as a cellulose source, its use has been neglected. This study uses N-methyl morpholine-N-oxide, an eco-friendly solvent, to dissolve denim (including 100 % cotton) and create a denim film. Achieving a 10 % denim record solubility, a cellulosic film was also fabricated for comparison. Characterisation techniques were applied, and molecular dynamics simulations explored intramolecular interactions and the influence of indigo dye on dissolution process. FTIR spectra indicated no chemical reactions during dissolution and regeneration, though a shift in OH stretching suggested a change in crystallinity, confirmed by XRD results showing decreased crystallinity and a structural shift from cellulose I to cellulose II. 13C NMR analysis revealed disruptions in interchain hydrogen bonds after regeneration. TGA results showed lower decomposition temperatures for both films compared to the powders. Testing mechanical properties showed the denim film had higher elongation at break but lower tensile strength than the cellulose film. MD simulations indicated indigo dye did not significantly affect fundamental interactions but decreased denim solubility by reducing the diffusion coefficient. Rheological tests supported the simulation results, showing higher viscosity and molecular weight for the denim solution compared to cellulose.

Effect of Y precursors on the synthesis of Cu-Y2O3 by mechanical alloying and spark plasma sintering

This work prepared the Cu-Y2O3 alloy through mechanical alloying and spark plasma sintering. Based on the in-situ reaction principle, Y salts were used as a precursor of Y2O3 dispersoid instead of pure Y powder, and the influence of different Y salts on the microstructure, mechanical, and physical properties of the copper matrix was researched. The results indicate that Y salts can effectively prevent the cold welding effect of pure Y metal powder, thereby improving the homogeneity and refinement effect of alloying. Among different Y salts samples, Y(NO3)3·6H2O and Y2(SO4)3·8H2O may cause varying degrees of contamination to the copper matrix, affecting the material properties. In comparison, Y2(CO3)3 has the advantage of low decomposition temperature and the decomposition product CO2 does not react with the copper matrix. It successfully refined the average particle size of Y2O3 from 8.8 ± 3.7 nm to 5.5 ± 2.8 nm, increased the number density from 2.37 × 1021/m3 to 7.46 × 1021/m3, and obtained a tensile strength of 291 MPa and an elongation of 19.8 % at room temperature, with a thermal conductivity of 322 W/(m K) at 400 °C for the Cu-Y2O3 alloy. This validates the feasibility of combining Y salts with mechanical alloying. The preparation of high-strength, high-conductivity Cu alloys holds significant reference value.

Low-Temperature Decomposition and Oxidation of the Nerve Agent Simulant on Mesoporous Nickel Oxide and Cu-Doped Nickel Oxide.

In an effort to develop the next frontier filtration material for chemical warfare agent (CWA) decomposition, we synthesized mesoporous NiO and CuxNi1-xO (x = 0.10 and 0.20) and studied the decomposition of CWA simulant diisopropyl fluorophosphate (DIFP) on their surfaces. Mesoporous NiO and CuxNi1-xO were fully characterized and found to be a solid solution with no phase separation up to 20% copper dopant. The synthesized materials were successfully templated producing ordered mesoporous metal oxides with high surface areas (67.89- 94.38 m2/g). Through Raman spectroscopy, we showed that pure NiO contained a high concentration of Ni2+ vacancies, while Cu2+ reduced these defects. Through in situ infrared spectroscopy, we determined the surface species formed, potential pathways, and driving factors for decomposition. Upon exposure of DIFP, all materials produced similar decomposition products CO, CO2, carbonyls, and carbonates. However, decomposition reactions were sustained longer on mesoporous NiO, facilitated by the higher Ni2+ vacancy concentration. NiO was further studied with DIFP, first at low dosing temperatures (-50 °C), which still resulted in the production of CO and carbonates, and then, second, with a higher pretreatment temperature, which showed the importance of terminal hydroxyls/water to fully oxidize decomposition products to CO2. Mesoporous NiO demonstrated high decomposition and oxidation capabilities at temperatures below room temperature, all without any external excitation or noble metals, making it a promising frontier filtration material for CWA decomposition.

Preparation of μ-HMX/C-Based Composite Energy Composite Microspheres by Microdroplet Technology.

Taking μ-HMX particles as the main research subject, a set of microdroplet sphericalization coating technology platforms was designed and constructed to realize the preparation of composite microspheres by sphericalization coating of μ-HMX. The suspension stability of μ-HMX particles and the mechanism of droplet formation were investigated, and the application effect of nanocarbon materials was also analyzed. The results showed that the prepared sample microspheres all showed a better spherical morphology, as well as good dispersibility; the samples with micron-sized particles for spherical coating had a lower thermal decomposition temperature, a higher energy release efficiency, lower mechanical sensibility, and better combustion performance; the incorporation of CNFs changed the combustion mode of the system, which resulted in the microsphere system of μ-HMX having a good safety performance. The stability and feasibility of uniform spheronization when the dispersed phase is a low-concentration particle suspension system in the spheronization encapsulation process by microdroplet technology were verified.

The synthesis and properties of low sensitivity and heat resistant guanidine salts

This paper uses a simple method to synthesis four guanidine salts of nitrophenols and tetrazoles with low sensitivity (friction sensitivity and impact sensitivity) and high decomposition temperature. The crystal structures were tested by an X-ray single crystal diffractometer. Thermal decomposition behaviors were examined via differential scanning calorimetry (DSC), revealing decomposition temperatures of 295.04 °C, 332.57 °C, 252.51 °C, and 301.17 °C, all exceeding 250.00 °C. The detonation velocities and pressures were calculated using Explo5 based on the experimentally measured combustion heat. The detonation velocities for the four guanidine salts followed the order 4 (7667 m s−1)＞ 2 (6909 m s−1)＞ 3 (6722 m s−1)＞ 1 (6560 m s−1), and the explosion pressures were ranked as 4 (19.13 GPa)＞ 2 (17.72 GPa)＞ 1 (14.96 GPa)＞ 3 (12.43 GPa). The combustion heats were measured using oxygen bomb calorimetry and were found to be 2 (11.85 kJ g⁻1) > 3 (11.66 kJ g⁻1) > 4 (11.31 kJ g⁻1) > 1 (10.57 kJ g⁻1). The impact sensitivity was greater than 100 J, and the friction sensitivity was greater than 360 N. Given these advantages, it is anticipated that these compounds could have applications in propellants and gas generators.

Tripiperidinium pentaformato copper(II) – A unique homoleptic Cu(II) formate

The synthesis, structure and thermal decomposition behaviour of unique mononuclear, homoleptic [pipH]3[Cu(O2CH)5] (2) (pipH+ = piperidinium) is discussed in which the copper(II) ion is exclusively coordinated by five formate anions forming a distorted square-pyramidal coordination sphere. Thermogravimetric studies confirmed a comparatively low decomposition temperature (Tonset = 107 °C) affording solely elemental Cu. Based on TG-MS experiments a decomposition mechanism is presented.______________________________________________________________________________

PFAS remediation: Evaluating the infrared spectra of complex gaseous mixtures to determine the efficacy of thermal decomposition of PFAS

Due to their widespread production and known environmental contamination, the need for the detection and remediation of per- and polyfluoroalkyl substances (PFAS) has grown quickly. While destructive thermal treatment of PFAS at low temperatures (e.g., 200–500 °C) is of interest due to lower energy and infrastructure requirements, the range of possible degradation products remains underexplored. To better understand the low temperature decomposition of PFAS species, we have coupled gas-phase infrared spectroscopy with a multivariate curve resolution (MCR) analysis and a database of high-resolution PFAS infrared reference spectra to characterize and quantify a complex mixture resulting from potassium perfluorooctanesulfonate (PFOS–K) decomposition. Beginning at 375 °C, nine prevalent decomposition products (namely smaller perfluorocarbon species) are identified and quantified.