Ozawa Method Research Articles

Experimental Study on the Thermal Behavior Characteristics of the Oxidative Spontaneous Combustion Process of Fischer–Tropsch Wax Residue

Coal-to-liquid technology is a key technology to ensuring national energy security, with the Fischer–Tropsch synthesis process at its core. However, in actual production, Fischer–Tropsch wax residue exhibits the characteristics of spontaneous combustion due to heat accumulation, posing a fire hazard when exposed to air for extended periods. This significantly threatens the safe production operations of coal-to-liquid chemical enterprises. This study primarily focuses on the experimental investigation of the oxidative spontaneous combustion process of three typical types of wax residues produced during Fischer–Tropsch synthesis. Differential Scanning Calorimetry (DSC) was used to test the thermal flow curves of the three wax residue samples. Kinetic analysis was performed using the Kissinger–Akahira–Sunose (KAS) and Flynn–Wall–Ozawa (FWO) methods to calculate their apparent activation energy. This study analyzed the thermal behavior characteristics, exothermic properties, and kinetic parameters of three typical wax residue samples, exploring the ease of reaction between wax residues and oxygen and their tendency for spontaneous combustion. The results indicate that Wax Residue 1 is rich in low-carbon chain alkanes and olefins, Wax Residue 2 contains relatively fewer low-carbon chain alkanes and olefins, while Wax Residue 3 primarily consists of high-carbon chain alkanes and olefins. This leads to different thermal behavior characteristics among the three typical wax residue samples, with Wax Residue 1 having the lowest heat release and average apparent activation energy and Wax Residue 3 having the highest heat release and average apparent activation energy. These findings suggest that Wax Residue 1 has a higher tendency for spontaneous combustion. This research provides a scientific basis for the safety management of the coal chemical industry, and further exploration into the storage and handling methods of wax residues could reduce fire risks in the future.

Study on Thermal Oxygen Aging Characteristics and Degradation Kinetics of PMR350 Resin.

The thermal stability and aging kinetics of polyimides have garnered significant research attention. As a newly developed class of high thermal stability polyimide, the thermal aging characteristics and degradation kinetics of phenylene-capped polyimide prepolymer (PMR350) have not yet been reported. In this article, the thermo-oxidative stability of PMR350 was investigated systematically. The thermal degradation kinetics of PMR350 resin under different atmospheres were also analyzed using the Flynn-Wall-Ozawa method, the Kissinger-Akahira-Sunose method, and the Friedman method. Thermogravimetric analysis (TGA) results revealed that the 5% thermal decomposition temperature (Td5%) of PMR350 in a nitrogen atmosphere was 29 °C higher than that in air, and the maximum thermal degradation rate was 0.0025%/°C, which is only one-seventh of that observed in air. Isothermal oxidative aging results indicated that the weight loss rate of PMR350 and the time-dependence relationship follow a first-order exponential growth function. PMR350 resin thermal decomposition reaction under air atmosphere includes one stage, with a degradation activation energy of approximately 57 kJ/mol. The reaction model g(α) fits the F2 model, and the integral form is given by g(α) = 1/(1 - α). In contrast, the thermal decomposition reaction under a nitrogen atmosphere consists of two stages, with degradation activation energies of 240 kJ/mol and 200 kJ/mol, respectively. The reaction models g(α) correspond to the A2 and D3 models, with the integral forms represented as g(α) = [-ln(1 - α)]2 and g(α) = [1 - (1 - α)1/3]2 due to the oxygen accelerating thermal degradation from multiple perspectives. Moreover, PMR350 resin maintained high hardness and modulus even after thermal aging at 350 °C for 300 h. The results indicate that the resin exhibits excellent resistance to thermal and oxygen aging. This study represents the first systematic analysis of the thermal stability characteristics of PMR350 resin, offering essential theoretical insights and data support for understanding the mechanisms of thermal stability modification in PMR350 and its engineering applications.

Ti/CuO Nanothermite-Study of the Combustion Process.

A study of the combustion processes of Ti/CuO and Ti/CuO/NC nanothermites prepared via electrospraying was conducted in this work. For this purpose, the compositions were thermally conditioned at 350, 550 and 750 °C, as selected based on our initial differential scanning calorimetry-thermogravimetry (DSC/TG) investigations. The tested compositions were analysed for chemical composition and morphology using SEM-EDS, Raman spectroscopy and XRD measurements. Additionally, the thermal behaviour and decomposition kinetics of compositions were explored by means of DSC/TG. The Kissinger and Ozawa methods were applied to the DSC curves to calculate the reaction activation energy. SEM-EDS analyses indicated that sintering accelerated with increasing equivalence ratio and there was a strong effect on the sintering process due to cellulose nitrate (NC) addition. The main combustion reaction was found to start at 420-450 °C, as confirmed by XRD and Raman study of samples annealed at 350 °C and 550 °C. Moreover, increasing the fuel content in the composition led to lower Ea, higher reaction heats and a more violent combustion process. Conversely, the addition of NC had an ambiguous effect on Ea. Finally, a multi-step combustion mechanism was proposed and is to some extent in line with the more general reactive sintering (RS) mechanism. However, unusual mass transfer was observed, i.e., to the fuel core, rather than the opposite, which is typically observed for Al-based nanothermites.

Investigation of thermal properties and structural characterization of novel boron-containing Schiff base polymers

Three novel Schiff base polymers were synthesized by using the Schiff base monomer obtained using aldehyde containing boric acid and amines containing hydroxyl groups as the starting materials. The polymers were synthesized at the same temperature and using the same amount of oxidizing agent by the oxidative polycondensation method. The characterization of all polymers and monomers was achieved by using Fourier transform infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV–vis), nuclear magnetic resonance spectroscopy (1H-NMR), liquid chromatography-mass spectrometry (LC–MS), gel permeation chromatography (GPC) and scanning electron microscopy (SEM). The thermal stability of these compounds was studied by employing thermogravimetric analysis (TGA), and thermodynamics parameters such as activation energy (Ea), enthalpy (∆H), entropy (∆S), and Gibbs free energy(∆G) for the decomposition process were calculated using the Flynn–Wall–Ozawa method.

Non-isothermal crystallization behavior of Cr50Fe6Co7Mo14C15B6Y2 metallic glass with super high content of Cr and integrated merits

In present work, non-isothermal crystallization behavior for novel Cr50Fe6Co7Mo14C15B6Y2 metallic glass (MG) with super high content of Cr and excellent merits was investigated by differential scanning calorimeter and X-ray diffraction. Both of the Kissinger and Ozawa methods show that the present glass transition is much harder than other transitions for a much larger apparent activation energy (E). While, the growth process of present second crystallization event is the easiest process, since it possesses the smallest E. Meanwhile, the local activation energy established by Kissinger-Akahira-Sunose and Ozawa-Flynn-Wall methods both exhibit a trend of increasing to the maximum value at first and then gradual decrease until the finish of the crystallization, indicating that the difficulty increases until to the maximum at first and then gradually decreases during crystallization. Moreover, all the local Avrami exponent n(x) possesses a value of about 0 <n(x) < 1.5, implying a crystallization with pre-existing nuclei for present non-isothermal crystallization. Furthermore, the glass formation melt of present MG is considered as an intermediate one with moderate thermal stability. Additionally, the alloy firstly changes from monolithic MG to a composite of amorphous matrix superimposed with the main crystalline phases ((Fe,Cr)23(C,B)6, (Cr2.5Fe4.3Mo0.1)C3, Fe3Mo3C, FeC and some unknown phases), and then the remained amorphous matrix thoroughly changes to these crystalline phases with enriched crystal planes and fraction during crystallization. The results can supply basic data for designing valid crystallization strategy to tune performances of metallic glasses with high content of Cr.

Synthesis and Polymerization of the Bio‐Benzoxazine Derived from Resveratrol and Thiophenemethylamine and Properties of its Polymer

AbstractResveratrol and 2‐thiophenemethylamine have been employed in the synthesis of a novel tri‐functional benzoxazine (RES‐th) to develop the bio‐benzoxazine monomer. The chemical structure of the synthesized monomer is confirmed by various characterization technics. The polymerization behavior is monitored by in situ Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC). The in situ FTIR results reveal distinct reaction mechanisms for the three oxazine rings presented in RES‐th, with both ether and phenolic Mannich bridge structures observed in the products. The activation energy values of RES‐th are calculated to be 119.05, 120.97, and 119.44 kJ mol−1 by Kissinger, Ozawa, and Starink methods, respectively, which are all based on the heat flow curves at various heating temperatures. The thermal stability and flame retardancy of the resulting polybenzoxazine (poly(RES‐th)) are investigated by thermogravimetric analysis (TGA) and microscale combustion calorimeter (MCC). The values of Td5 and Td10 of polybenzoxazine are found to be 356 °C and 399 °C, respectively, with a char yield of 66.3% at 800 °C. The prepared polybenzoxazine also demonstrates nonflammability characteristics with the values of heat release capacity (HRC) and total heat release rate (THR) of 18.65 J (g K)−1 and 2.69 kJ g−1, respectively. These findings suggest that the thermoset, poly(RES‐th), is a promising candidate for fire‐resistant applications.

Parameter estimation of epoxy resin cure kinetics by dynamics DSC data

AbstractThis study focused on determining the curing kinetic parameters of amine‐epoxy resin by performing dynamic DSC tests. The Kissinger and Crane equations were used to determine the activation energy, the pre‐exponential factor, and the reaction order as kinetic parameters for curing. The Ozawa equation was also used to determine the activation energy that changes at different levels of cure during the reaction. The average activation energy obtained by the Ozawa method was compared with the Kissinger activation energy. In addition, the T‐β extrapolation method was used to determine the optimum curing temperature. The kinetic parameters obtained from the Kissinger and Crane equations were used in the nth‐order kinetic model to predict the degree of cure at a given time and temperature. The linear regression fitting method was used in Minitab software to determine the curing parameters. The results were evaluated based on the fitting parameters. This study provides a theoretical basis for the curing mechanisms of epoxy matrix fiber composites used in the manufacture of wind turbine blades.

Pyrolysis of metal oxides treated Canarium schweinfurthii Shell: Investigation of thermogravimetric kinetics and thermodynamics

Metal oxides as catalysts alter the properties of the pyrolysis vapor secondary reactions during the thermal decomposition of several biomass leading to high-value bio-oils. This study aimed to investigate the thermal decomposition characteristics of Canarium Schweinfurthii (CS) shells that were treated with various metal oxides (ZnO, CuO, Fe2O3/FeO, and Fe2O3) using pyrolysis. The study also sought to identify pyrolysis reaction parameters (kinetics and thermodynamics parameters) that are not widely documented. Thermogravimetric pyrolysis was carried out at different heating rates, and the undocumented pyrolysis kinetic parameters were determined using the Flynn-Wall Ozawa method (FWO) according to American Standard Testing and Materials (ASTM) 6441 guidelines for assessing biomass decomposition. The metal oxide-treated CS shells lost significant weight between 62 and 67 wt% during the thermogravimetric pyrolysis, lower than 75 wt% of the CS shell. The average activation energies (Eα) for pyrolysis of the ZnO, CuO, Fe2O3/FeO, and Fe2O3 treated CS shells were 203.04, 155.35, 338.85, and 219.92 kJ/mol, respectively in contrast to that of the untreated CS-shell. The Bayesian Information Criteria revealed that the diffusion kinetics of the Gistling-Brounshtein model best describes the pyrolysis of the shell mixed with metal oxides. The metal oxides affected the CS shells' pyrolysis kinetic parameter (Eα), which can promote pyrolysis vapor upgrading to encourage the widespread use of metal oxides in pyrolysis for bioenergy and chemical recovery.

Potential reuse of HMX separated from decommissioned propellants: crystallization and characterization of low-sensitivity HMX

ABSTRACT Herein, in order to increase the purity and improve the performance of HMX crude products (Raw HMX) isolated from decommissioned propellants, a new method to obtain submicron levels using the solvent-anti-solvent process was proposed. Two different morphologies of HMX, regular prismatic vs. spherical-like, were obtained by means of two solvents (DMSO, DMF). Polyethylene glycol-200 (PEG-200) was used to improve the morphology and dispersion of crystals at low saturation and low crystallization temperatures. Various rates of addition of anti-solvent (water) were studied to prevent HMX crystalline transition and effectively increase purity. Furthermore, the aging process was applied to further modify the crystals with controlled particle size distribution The purity of the samples was tested by High Performance Liquid Chromatography (HPLC) spectroscopy, and the purity of the crystallized samples was improved from 95.53% in Raw HMX to over 99%. The thermal decomposition properties were investigated by differential scanning calorimetry (DSC) and the kinetic parameters of the thermal decomposition reaction of the materials were calculated using the Kissinger and Ozawa method. The samples were also tested for impact and friction sensitivity, which was reduced compared to both Raw HMX and industrial HMX, demonstrating that this type of modified HMX recovered from decommissioned propellants is fully reusable.

Thermal and calorimetric investigations of some vegetative fuels

AbstractBushfires pose a significant threat to numerous countries, often causing vast property damages and loss of lives. Efforts to combat and manage these fires heavily rely on predicting the fires' rate of spread and intensity. A significant component of these predictions involves understanding the thermophysical characteristics of vegetative fuels. The accuracy of predictive models (especially physical models) also depends on obtaining precise thermophysical and combustion parameters. This research aims to provide a comprehensive set of thermal degradation and combustion parameters for surface and near‐surface fuel samples collected during prescribed fire experiment conducted in April 2022 in Little Desert National Park, Victoria, Australia. Firstly, fuel properties like fuel height, moisture content, bulk density, fuel load and heat of combustion were meticulously characterized for both surface and near‐surface samples. Then activation energies for degradation reactions were determined using the Flynn–Wall–Ozawa method and for the determination of pre‐exponential factors, in most cases these reactions closely aligned with a Second order model. This was followed by determination of other parameters such as heat of reaction, specific heat and conductivity. It was found that the density, activation energy and heat of combustion did not vary significantly across the six samples under question. The comprehensive set of obtained parameters will likely help to facilitate better predictions in fire propagation modelling.

The phase structure, transitions, and non-isothermal crystallization kinetics of Zn2V2O7 glass

The Zn2V2O7 glass was prepared by solid-state reaction using the initial reactant ZnO and V2O5 powder. X-ray diffraction was employed to characterize the phase composition of the as-prepared Zn2V2O7 powder. The crystallization kinetics of Zn2V2O7 glass prepared by solid-state reaction was studied using differential thermal analysis under non-isothermal conditions. It was established that the crystallization process of Zn2V2O7 can be divided into two steps, which is controlled first by a Disc-like with kinetic equation G(α)=[-ln(1-α)]1/3 and then by a Fibril-type growth type with kinetic equation G(α)=[1-(1-α)1/3]1/2 . The apparent activation energy calculated by different methods (Kissinger method, Ozawa method, Tang method, and Starink method) under non-isothermal conditions were similar, varying between 335.6 kJ·mol−1 and 371.6 kJ·mol−1, and the average apparent activation energy was equal to 362.2 kJ·mol−1.

Gas-to-Biochar Byproducts of Pyrolysis and Gasification of Star Anise Biomass

In a transition to a circular economy, second-generation biomass energy has come to the forefront. The present study is aimed at characterizing biochar and byproducts of the pyrolysis of star anise residue (ANI) in the N2 and CO2 atmospheres as well as the kinetics and optimal reaction mechanisms based on the Flynn–Wall–Ozawa and Coats-Redfern methods. The ANI pyrolysis involved three stages, with the first one (161.5–559.1°C) as the main phase. The activation energy was lower in the N2 atmosphere than in the CO2 atmosphere (179.44–190.17 kJ/mol). The primary volatile products generated during the ANI pyrolysis were small molecule products (H2O, CO2, CO, and CH4), organic acids, alcohols, and ketones. The atmosphere type exerted a minimal impact on the types of gases released, with the CO2 atmosphere increasing CO and CH4 emissions. The pyrolytic oil of ANI contained a variety of organic compounds, including alcohols, phenols, ketones, acids, sugars, and other nitrogen- and oxygen-containing cyclic compounds, with its predominant compounds being acids, esters, ketones, and sugars. The elevated temperature range of 300–700°C enhanced the charring degree of the ANI biochar. The biochar showed stronger aromaticity in the CO2 atmosphere but better granularity in the N2 atmosphere. This study introduced an innovative perspective by showcasing the potential of ANI as a promising biomass source for energy generation and underscored its abundance, sustainability, and applicability as a raw material in fragrance production. It also emphasized the significance of CO2-reuse technology as a means to mitigate CO2 emissions. The findings of this work offer a theoretical and practical basis for the comprehensive utilization and efficient disposal of star anise residues.

Curing Kinetics of Epoxy Adhesive by Non-Isothermal DSC

Non-isothermal DSC has been used to investigate the curing kinetics of epoxy adhesives (DGEBA-cycloaliphatic amine). The epoxy samples were scanned on DSC with five heating rates (5°C/min, 7.5°C/min, 10°C/min, 12.5°C/min, and 15°C/min). The curing kinetics were obtained through ASTM standards E2890 and E698 (the Ozawa and Kissinger methods). The kinetic parameters obtained include Ea (activation energy), A (pre-exponential factor), and n (reaction order). The activation energy calculated from the Kissinger and Ozawa method was slightly different but insignificant. The reaction rate (dα/dt) and degree of curing/conversion (α) relationship towards temperature (T), and time (t) was also investigated. The curing process's reaction rate (dα/dt) has maximum value; it can no longer increase after a specific conversion rate (α).

Thermal decomposition kinetics and compatibility of NH3OHN5

AbstractHydroxylammonium cyclo‐pentazolate (NH3OHN5), as one of the poly‐nitrogen compounds, has a broad prospect in the field of energetic materials, due to its high specific impulse, high detonation velocity, and the pollution‐free products. In this paper, the thermal decomposition behavior of NH3OHN5 was studied by differential scanning calorimetry (DSC) using four heating rates (2, 5, 8, 10 °C min−1). The apparent activation energy (EK,O=114.31 kJ mol−1), the pre‐exponential factor (AK=4.78×1011 s−1) and the critical temperature of the thermal explosion (Tb=108.08 °C) of NH3OHN5 were calculated by Kissinger and Ozawa method under non‐isothermal heating conditions. The compatibility of NH3OHN5 with 1,3,5‐trinitro‐1,3,5‐triazacyclohexane (RDX), 1,3,5,7‐tetranitro‐1,3,5,7‐tetraazacyclooctane (HMX), 2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaza‐isowurtzitane (CL‐20), ammonium perchlorate (AP), and hydroxy‐terminated polybutadiene (HTPB) were tested and judged based on a standard agreement (STANAG‐4147). The DSC results showed that NH3OHN5/HMX, NH3OHN5/RDX, NH3OHN5/CL‐20, NH3OHN5/AP and NH3OHN5/HTPB had good compatibility.

Thermo‐Kinetic Study of Piperazine Immobilized Silica Surface

AbstractIn the present study, the degradation process of piperazine (PP) immobilized silica gel (SiPP) is investigated under dynamic conditions. The degradation of SiPP is studied with thermogravimetric analyzer (TGA). The kinetics of degradation process is analyzed by Kissinger method, Flynn–Wall–Ozawa's (FWO) method, and Deconvolution method. It is found that degradation of SiPP can be described by parallel independent two‐portion process model, which includes two processing state of the system (marked by processes 1 and 2), where process 1 and 2 can be attributed to decomposition processes of organic moiety attached on silica surface. The apparent activation energy (Ea) is calculated by Flynn–Wall–Ozawa's (FWO) method and deconvolution method.

Porous‐structured vermiculite/polybutylene adipate terephthalate composite films: The morphology, mechanical properties, and nonisothermal degradation kinetics

AbstractTo examine the impact of vermiculite (VMT) on the environmental and physical aspects of polybutylene terephthalate (PBAT), the thermal degradation behavior of VMT/polybutylene terephthalate polyadipate (VMT/PBAT) composite films was investigated by using the thermogravimetric analysis (TGA). To ensure precise calculation of the specific activation energy values of VMT/PBAT composite films in thermal degradation performance experiments, the Kissinger method (K‐method) and Flynn–Wall–Ozawa method (FWO method) were utilized. Additionally, the reaction mechanism was analyzed using the Coats–Redfern equation (CR equation). The introduction of VMT into the PBAT co‐polyester structure leads to an increase in the thermal degradation activation energy Ek of composite films.; the apparent activation energies were calculated by the Coats–Redfern method for different reaction mechanisms, and the interfacial diffusion reaction mechanism of the composite film was determined, with a thermal degradation reaction principle properties of g(α) = [1 − (1 − α)]2 and the number of reaction steps of 2.Highlights VMT/PBAT composite films prepared using a simple method. Analyzing nonisothermal degradation kinetics using K‐method and FWO method. Analyzing the degradation mechanisms using the Coats–Redfern equation. Addition of VMT enhances the thermal degradation properties of composite films. Addition of VMT reduces the mechanical properties of the composite film.

Co-combustion characteristics and kinetics of sludge/coal blends in 21%–50% oxygen-enriched O2/CO2 atmospheres

This research investigated the thermogravimetric analysis (TGA) and combustion kinetics of sewage sludge and Australian sub-bituminous coal and their blends with different mixing ratios (sludge/coal = 100/0, 80/20, 50/50, 20/80, 0/100 by weight) under air atmosphere (O2/N2 = 21/79 by volume), oxy-fuel combustion (O2/CO2 = 21/79, 25/75, 35/65, and 50/50 by volume), and pyrolysis (pure N2 atmospheres). The gaseous products that evolved from the TGA experiments were also analyzed using a Fourier transform infrared (FTIR) spectrometer under pyrolysis conditions. Results showed that the mixed fuel with higher coal blending ratio had higher ignition temperature, lower burnout temperature and larger combustion characteristic index. Furthermore, TGA–FTIR experiments of the 20 % sludge + 80 % coal blended fuel under nitrogen atmospheres showed more gasification components in pure coal than in sludge. The combustion kinetics analytical results via the Flynn–Wall–Ozawa method indicated that the larger the conversion degree, the smaller the obtained activation energy value. Under the oxy-fuel combustion conditions, when the oxygen concentration increased from 21 % to 50 % for the 20 % sludge + 80 % coal blended fuel, the ignition and burnout temperatures decreased, and the combustion characteristic index increased nearly three times. Oxygen enrichment can clearly improve combustion characteristics and flammability.

Effect of sludge-based suppression materials on the explosive flame characteristics of aluminium dust

A study was conducted to investigate the inhibitory effect of sludge-based phosphate-containing composite powder explosion suppressants (MPP/AMS) on aluminium dust explosion and combustion. The experiment compared the inhibition characteristics of ordinary sewage sludge particles, high-temperature alkali-modified sludge particles, phosphate-containing particles, and phosphate-modified sludge particles. The study utilized a flame propagation experimental device and an explosion pressure testing device for comprehensive research. The experimental recording devices revealed that sludge-based composite powder explosion suppressants effectively inhibit aluminium powder explosion and combustion. Thermodynamic analysis of the rapid oxidation stage was performed using the Coats Redfern (C-R) method, and validation was conducted using the Flynn Wall Ozawa (FWO) and Kissinger Akahira Sunose (KAS) methods. The results theoretically explain that sludge-based composite powder explosion suppressants can effectively suppress aluminium powder explosions and exhibit a blocking effect. Surface morphology and material element characterization experiments were conducted before and after the explosion, combined with pyrolysis characteristics. The analysis demonstrated that the inhibition mechanism of sludge-based composite powder explosion suppressants on aluminium powder explosion primarily involves two aspects: physical inhibition (MPP coating inhibition, porous adsorption isolation) and chemical inhibition (decomposition heat absorption, product oxidation). The theoretical findings provide evidence of the superior inhibitory effects of sludge-based composite powder explosion suppressants, offering new insights for the resource utilization of sludge waste and the development of novel explosion suppression materials.

Study on synthesis and characterization of spherical copper(I) 5‐nitrotetrazolate (DBX‐1)

AbstractTraditional primary explosives often contain heavy metals, especially toxic lead, such as lead azide (LA) and lead styphnate (LS) that can cause environmental pollution problems. Copper(I) 5‐nitrotetrazolate (DBX‐1) is a green primary explosive without toxic heavy metals, which is considered as one of the most promising alternatives to LA. DBX‐1 is usually synthesized from sodium 5‐nitrotetrazolate dihydrate (NaNT ⋅ 2H2O) and copper(I) chloride (CuCl). However, most of the synthesized products are irregular flakes with poor flowability, which affects the loadability. In this study, dextrin was used as a crystal shape modifier to improve the morphology of the synthesized product. Taguchi analysis method was used to determine the optimal experimental conditions for obtaining the spherical DBX‐1 with smaller particle size. The synthesized products were characterized by SEM, FTIR, UV‐Vis, STA TG‐DSC and VST, and their sensitivity was determined by BAM fallhammer, BAM friction tester and electrostatic spark sensitivity tester. The experiment results showed that the optimal combination of synthesis parameters was the NaNT ⋅ 2H2O concentration of 4.4 wt.%, the reaction temperature of 100 °C, the reaction time of 75 min and the additional dextrin solution of 5.0 mL. The average particle size of the synthesized spherical DBX‐1 was 33.0 μm. The decomposition activation energy was calculated by Kissinger method and Ozawa method to be 178.5 and 178.8 kJ/mol, respectively. The compound had good chemical stability. In addition, the sensitivity of spherical DBX‐1 was lower compared to that of flaky DBX‐1 and LA.

Silver/polydopamine/HMX nanocomposite: novel functionalized catalyzed energetic matrix with superior decomposition kinetics

Surface engineering of energetic materials can secure novel decomposition characteristics. Nature can inspire novel solutions. Polydopamine, with strong adhesion power of mussel proteins, can open new venues for the facile development of functionalized energetic materials. HMX, one of the most powerful energetic materials in use, was surface modified with PDA. The reactive amine groups of PDA surfactant were employed for noble metal catalyst deposition. Silver nanocatalyst was deposited on HMX surface. Uniform deposition of silver nanocatalyst was assessed using EDAX detector. Decomposition kinetics was investigated via isoconversional (model free) and model fitting. Kissinger, Kissinger–Akahira–Sunose (KAS), integral isoconversional method of Ozawa, Flynn, and Wall (FWO), and differential isoconversional method of Friedman. Silver nanocatalyst offered an increase in HMX decomposition enthalpy by 32.4%. In the meantime, HMX activation energy was decreased from 350 ± 2.53 to 284.9 ± 1.5 kJ mol−1 by Friedman method. Silver nanocatalyst could combust exothermically; it could induce condensed phase reactions that could boost HMX decomposition. Silver nanocatalyst experienced change in HMX decomposition model from diffusion reaction (D1) to (A3) known as three-dimensional random nucleation and growth. Surface modification with PDA secured enhanced HMX sensitivity to falling mass impact by 40%.