Two-step Reaction Mechanism Research Articles

Two-Step Noncatalyzed Hydrolysis Mechanism of Imines at the Air-Water Interface.

The hydrolysis of imines has long been assumed to be their main atmospheric fate, based on early studies in the field of organic chemistry. However, the hydrolysis mechanism and kinetics of atmospheric imines remain unclear. Here, an advanced Born-Oppenheimer molecular dynamics method was employed to investigate the noncatalyzed hydrolysis mechanism and kinetics at the air-water interface by selecting CH2NH as a model molecule. The results indicate that CH2NH exhibits a pronounced surface preference. The noncatalyzed hydrolysis of CH2NH follows a unique two-step reaction mechanism involving first proton transfer and then OH- transfer through the water bridge at the air-water interface, in contrast to the traditional one-step mechanism. The calculated reaction rate for the rate-determining step is 3.32 × 105 s-1, which is 2 orders of magnitude greater than that of the bulk phase. In addition, the involvement of the interfacial electric field further enhances the reaction rate by approximately 3 orders of magnitude. The noncatalyzed hydrolysis rate at both the air-water interface and the bulk phase is higher than that of the possible acid-catalyzed one, clarifying noncatalyzed hydrolysis as the dominant mechanism for CH2NH. This study elucidates that the noncatalyzed hydrolysis of atmospheric imines is feasible at the air-water interface and that the revealed unique two-step hydrolysis mechanism has significant implications in atmospheric and water environmental chemistry.

Top-Down Synthesis of N-Type PbS Quantum Dots with High Photoluminescence Quantum Yield from Microsized Pb(OH)Cl.

Synthesis of PbS quantum dots (QDs) with uniform and controllable size is of great importance in realizing functionality manipulation, as well as building advanced devices, and these QDs have been normally synthesized via "bottom-up" colloidal chemistry. However, the problems of complicated techniques and the relative high cost of the "bottom-up" methods still need to be overcome. Herein, we present a facile and cost-effective "top-down" strategy for the production of PbS QDs with controllable sizes and narrow dispersions (4.8% < σ < 7%) based on the sulfuration reaction of highly active lead oxide and oxychloride intermediates. We investigated the two-step reaction mechanism of the QD synthesis. Initially, Pb(OH)Cl undergoes a reaction with oleic acid in the presence of oleylamine as an activator, leading to the formation of active lead oxide/oxychloride intermediates. Notably, this distinctive reaction induces the creation of numerous cracks within the intermediates, thereby augmenting the active sites available for the subsequent sulfuration reactions. In that, the sulfur precursor reacts with the intermediates, resulting in the rapid generation of a substantial number of PbS fragments. Over time, these small fragments undergo "ripening" until reaching the "critical" size threshold. Different from the ones obtained by the traditional "bottom-up" method, our synthesized colloidal QDs exhibit a S-rich surface and are confirmed to be N-type. In addition, size-tunable near-infrared photoluminescence renders these QDs a promising material for various applications.

Linkage-Mixed Covalent Organic Frameworks Synthesized by a Liquid-Solid Two-Phase Strategy for Photoenhanced Uranium Extraction.

Synthesizing COFs with hybrid linkage coupling with both reversible and irreversible natures remains a challenging issue. Herein, we report the synthesis of two rare COFs constructed by both reversible and irreversible linkages through a liquid-solid two-phase strategy. A systematic study reveals a one-pot, two-step reaction mechanism for the two COFs, the first step being a reversible Schiff base reaction and the second step being an irreversible Knoevenagel reaction. Interestingly, this hybrid linkage COF is found to show an outstanding photoenhanced uranium extraction performance. The results not only provide a general and green approach to develop the linkage chemistry of COFs but also enrich the synthesis toolboxes and application of COFs.

Mathematical and sensitivity analysis for chemical species in multistep dynamical system: A computational study

This study presents a significant contribution to the field of chemical kinetics by providing a detailed analysis of a multi-step chemical kinetic process using ordinary differential equations (ODEs). The aim is to describe complex chemical processes' kinetics and the steady-state behavior of chemical species. The research employs reduction techniques to simplify the model by separating fast and slow processes based on their time scales, with a focus on a two-step reversible reaction mechanism. Special consideration is given to the phase flow of solution trajectories near equilibrium points, providing a clear depiction of system behavior. MATLAB simulations demonstrate the physical properties of observed data, while sensitivity analysis reveals parameters' impact on species behavior. Overall, this study enhances our understanding of chemical kinetics and offers insights into modeling complex reaction processes, with implications for various applications in chemistry and related fields.

Fidelity in plant hormone modifications catalyzed by Arabidopsis GH3 acyl acid amido synthetases

GRETCHEN HAGEN 3 (GH3) acyl acid amido synthetases conjugate amino acids to acyl acid hormones to either activate or inactivate the hormone molecule. The largest subgroup of GH3 proteins modify the growth-promoting hormone auxin (indole-3-acetic acid; IAA) with the second largest class activating the defense hormone jasmonic acid (JA). The two-step reaction mechanism of GH3 proteins provides a potential proofreading mechanism to ensure fidelity of hormone modification. Examining pyrophosphate release in the first-half reaction of Arabidopsis GH3 proteins that modify IAA (AtGH3.2/YDK2, AtGH3.5/WES1, AtGH3.17/VAS2), JA (AtGH3.11/JAR1), and other acyl acids (AtGH3.7, AtGH3.12/PBS3) indicates that acyl acid-AMP intermediates are hydrolyzed into acyl acid and AMP in the absence of the amino acid, a typical feature of pre-transfer editing mechanisms. Single-turnover kinetic analysis of AtGH3.2/YDK2 and AtGH3.5/WES1 shows that non-cognate acyl acid-adenylate intermediates are more rapidly hydrolyzed than the cognate IAA-adenylate. In contrast, AtGH3.11/JAR1 only adenylates JA, not IAA. While some of the auxin-conjugating GH3 proteins in Arabidopsis (i.e., AtGH3.5/WES1) accept multiple acyl acid substrates, others, like AtGH3.2/YDK2, are specific for IAA; however, both these proteins share similar active site residues. Biochemical analysis of chimeric variants of AtGH3.2/YDK2 and AtGH3.5/WES1 indicates that the C-terminal domain contributes to selection of cognate acyl acid substrates. These findings suggest that the hydrolysis of non-cognate acyl acid-adenylate intermediates, or proofreading, proceeds via a slowed structural switch that provides a checkpoint for fidelity before the full reaction proceeds.

Computing the solution trajectories, steady state approximation, and sensitivity analysis in complex chemical reaction mechanism

Ordinary differential equations are often employed in chemical kinetics mathematical modeling. The theoretical results for a model of a multi-step chemical kinetic process are presented in this article. This model seeks to describe both the complicated kinetics of complex chemical processes and the steady state behavior of chemical species. Reduction techniques are used to divide fast and slow processes according to their time scales, which simplifies the model. As a result, the quick processes are removed, making the slow processes the main emphasis of a reduced-dimensional model. The paper concentrates on a two-step reversible reaction mechanism for model reduction, which reduces the complexity of the entire reaction process. The phase flow of solution trajectories close to equilibrium points is also given special consideration in the analysis as it offers a clear and pertinent depiction of the behavior of the system. The physical properties of the observed data are further shown via MATLAB simulations. Sensitivity analysis computes parameters, revealing their impact on species behavior, visually presenting the parameter impact.

Loss of fluorine during crosslinking by the biarylitide P450Blt proceeds due to restricted peptide orientation.

The biarylitide crosslinking enzyme P450Blt can perform crosslinking between m-F-Tyr-3 and His-5 residues within peptide substrates with concomitant and specific loss of fluorine. Our investigations suggest that a small intrinsic preference for coupling ipso to fluorine is magnified by the binding of the peptide in a specific orientation that enforces the loss of fluorine during peptide crosslinking, likely via a two-step reaction mechanism involving the non-enzyme catalysed reductive elimination of fluoride.

Preparation of corn straw-based carbon by “carbonization-KOH activation” two-step method: Gas–solid product characteristics, activation mechanism and hydrogen storage potential

Making excellent carbon-based hydrogen adsorbents requires thoroughly understanding the two-step activation method's reaction mechanism. This research examined the properties of gases and solids with high KOH/biochar ratios (4:1), various carbonization temperatures (400–600 °C), and activation temperatures (700–900 °C). The potential of biochar for hydrogen storage was further examined. These results demonstrate the division of the KOH activation process into four temperature-dependent reaction stages. The emission of CH4, CO, and H2 in various temperature ranges can be significantly influenced by the degree of carbonization and activation temperature. The outcome of activation is primarily determined by the volatile content and reactivity of carbon precursors. Biochar produced at 400 °C for carbonization and 900 °C for activation has a specific surface area (SSA) of 3567.33 m2/g. The oxygen concentration of H-400 decreases as the activation temperature rises, whereas the oxygen-containing structure can be built by raising the carbonization level. The hydrogen storage capacity of biochar was 2.49 wt.% at −196 °C and 1 bar, and increased to 5.51 wt.% at 50 bar, while it is 0.43 wt.% at 50 bar and room temperature. These findings can provide a novel strategy for developing carbon-based hydrogen storage materials.

Real-Time Monitoring of the Structural Transition of Bombyx mori Liquid Silk under Pressure by Solid-State NMR.

Silk fibroin is stored in the silk glands of Bombyx mori silkworms as a condensed aqueous solution called liquid silk. It is converted into silk fibers at the silkworm's spinnerets under mechanical forces including shear stress and pressure. However, the detailed mechanism of the structural transition of liquid silk to silk fibers under pressure is not well understood. Magic angle spinning (MAS) in solid-state nuclear magnetic resonance (NMR) can exert pressure on liquid samples in a quantitative manner. In this study, solid-state NMR was used to quantitatively analyze the impact of pressure on the structural transition of liquid silk. A combination of 13C DD-MAS and CP-MAS NMR measurements enabled the conformation and dynamics of the crystalline region of the silk fibroin (both before (Silk Ip) and after (Silk IIp) the structural transition) to be detected in real time with atomic resolution. Spectral analyses proposed that the pressure-induced structural transition from Silk Ip to Silk IIp proceeds by a two-step autocatalytic reaction mechanism. The first reaction step is a nucleation step in which Silk Ip transforms to single lamellar Silk IIp, and the second is a growth step in which the single lamellar Silk IIp acts as a catalyst that reacts with Silk Ip molecules to further form Silk IIp molecules, resulting in stacked lamellar Silk IIp. Furthermore, the rate constant in the second step shows a significant pressure dependence, with an increase in pressure accelerating the formation of large stacked lamellar Silk IIp.

Influence of Heat Loss on the Chaotic Dynamics of Reaction Waves in the Model with Chain-Branching Reaction

In this paper, the complex dynamics of the pulsating regime of combustion waves propagation is numerically investigated within the Zel’dovich–Barenblatt–Dold model with two-step chain-branching reaction mechanism. It is shown that there exists a remarkable similarity in the dynamics of oscillations in this system and one-dimensional discrete-time maps such as the logistic map. In particular, both systems exhibit the period doubling route to chaos and the appearance of windows of stability as the bifurcation parameter is increased. For the first time for a model of combustion wave propagation the sequence of windows of stability is demonstrated and classified. Nevertheless, as the activation energy, which is taken as a bifurcation parameter, reaches a critical value corresponding to the dynamical quenching scenario the dynamics of the flame oscillations becomes multidimensional and therefore it cannot be described by a one-dimensional map anymore. The effect of the heat losses is also studied and it is demonstrated that the number of windows of stability decreases, the order of their appearance changes and the dynamical quenching appears for smaller values of the activation energy as the heat losses are increased.

Thermal hazard assessment of tert-butyl perbenzoate using advanced calorimetric techniques and thermokinetic methods

Tert-butyl perbenzoate (TBPB) is a common organic peroxide initiator in the polymer sector, and its thermal behavior and potential dangers are explored in this quantitative study. Advanced calorimetric techniques and thermokinetic models were used to examine the thermal stability and breakdown features of TBPB. During the first stage of the TBPB synthesis, the process safety analysis revealed a very exothermic reaction. Peak temperatures for TBPB thermal decomposition ranged from 133.37 to 156.64 °C, with heat release values of roughly 1279 ± 135 J/g, as determined by differential scanning calorimetry and thermogravimetric analysis. Apparent activation energies ranged from 78.78 to 133.92 kJ/mol in a thermokinetic analysis employing the Kissinger, Starink, ASTM E698, Friedman, Kissinger-Akahira-Sunose, and Flynn-Wall-Ozawa models. Based on multiple nonlinear regression analysis, a two-step reaction mechanism was postulated, one involving an autocatalytic reaction and the other involving a reaction of the nth order. In order to evaluate the thermal dangers related with TBPB, the self-accelerating decomposition temperature (SADT) and thermal risk index (TRI) were calculated. Based on TRI calculations, TBPB was assessed as having low thermal risk, with SADT values ranging from 40 to 60 °C depending on package size. These numerical findings add to our knowledge of the thermal risks posed by TBPB and shed light on how best to handle, store, and transport the compound for use in industrial settings.

Effects of the perturbation inlet on the evolution and oscillation characteristics of multiple rotating detonation waves

A numerical simulation using the open-source platform OpenFOAM is conducted to investigate the effect of periodic perturbations at the inlet on the evolution and oscillation characteristics of multiple rotating detonation waves (RDWs). The study uses a two-step chemical reaction mechanism of C2H4/Air. The results reveal that periodic perturbations have a significant effect on the pressure, detonation wave height, heat release rate, thrust, and specific impulse of the rotating detonation engine. The oscillation pattern of these parameters is found to be highly correlated with the form of the inlet perturbations. The study also examines the evolution mechanism of multiple detonation waves and identifies three primary propagation stages under inlet perturbations: chaotic propagation, self-adjustment, and oscillatory propagation. The multiple detonation waves originate from the chaotic propagation and are mainly adjusted in terms of the number and direction of detonation waves through the double-wave collision. The results demonstrate that increasing the amplitude of perturbations poses a significant risk to the survival of the RDW, while high-frequency perturbations may disrupt the three primary propagation stages, leading to predominantly the chaotic propagation. Furthermore, an analysis of the fast Fourier transform of the thrust and specific impulse shows that the oscillation forms of the specific impulse and thrust differ in the chaotic propagation stage.

Phosphorus extracted municipal sludge-derived hydrochar as a potential solid fuel: Effects of acidic leaching and combustion mechanism

Hydrochar from hydrothermal liquefaction (HTL) of municipal sludge is often seen as waste. Initially, acidic leaching has been performed on hydrochar to recover phosphorus. This study evaluated the resulting hydrochar as solid fuel, thus achieving zero waste for integrating HTL into wastewater treatment plants. The effects of various leaching conditions on acid-modified hydrochar properties were examined. Compared to raw hydrochar, acid-modified hydrochar had a significant ash reduction (up to 44%). The leaching conditions (10 mL of 0.6 N HNO3/g for 2 h) for near-complete phosphorus extraction also achieved the following most desirable properties of acid-modified hydrochar: Maximized fuel ratio (1.3), higher heating value (20.5 MJ/kg), carbon content (48%), and minimized ash content (34%) on a dry basis. By removing most alkali and alkaline earth metals, acid-modified hydrochar could carry a low slagging and fouling risk compared to a high/severe risk for raw hydrochar. Acidic leaching also enhanced ignition temperature from 317 to 351 °C for safer storage and transportation of hydrochar, with a higher comprehensive combustion index (up to 9.9 × 10−8 min−2 °C−3). Overall, hydrochar fuel property was improved by acid modification, comparable to bituminous coal. For the first time, it was identified that hydrochar combustion was controlled by a two-step nth-order reaction mechanism f(α) = (1 − α)n with the reaction order changing from 3 to 1 as progressed. The acid modification did not affect combustion mechanisms but reduced activation energy in the first stage. The results demonstrated a sustainable approach for closing the waste loop and provided a pathway for transforming hydrochar into biofuel.

Strategies for heat recovery in a reverse flow reactor designed to lessen coal mine methane emissions test

ABSTRACT Thermal pollution resulting from the release of ventilation air methane (VAM) has emerged as a pressing concern in coal mining. This study aims to address this issue by harnessing the waste VAM energy and converting it into reusable resources, employing an efficient thermal flow reversal reactor. The research investigates five distinct heat extraction strategies and compares their performance. The numerical analysis focuses on transient heat recovery performance by employing a two-step reaction mechanism. Furthermore, the study uncovers the heat transfer characteristics of heat exchange tubes and conducts an analysis of construction costs and profit periods for the different strategies. The findings indicate that the central heat recovery strategy exhibits inferior recovery performance, resulting in higher outlet temperatures and lower extracted power. Conversely, the end recovery strategy successfully reduces heat loss by 56%. The two-sided strategy demonstrates better recovery performance, maintaining an average outlet temperature of 311 K. Additionally, the heat recovery efficiency of the heat exchange tube is approximately 85.6%. Although the combination strategy appears to reduce outlet heat loss, it results in an extended investment payback period.

A DNS study of pulverized coal combustion in a hot turbulent environment: Effects of particle size, mass loading and preferential concentration

In the present study, pulverized coal combustion in a hot turbulent environment is investigated using direct numerical simulation (DNS). The coal particles are tracked in the Lagrangian framework while the flow is solved in an Eulerian way. A model involving two competing reactions is used for describing the process of coal devolatilization. The volatile matter is treated as a postulated substance (CaHbOc) and a two-step global reaction mechanism for volatile combustion is adopted. The char combustion is modeled using a one-step global reaction model. The effects of various factors, such as particle size, mass loading and preferential concentration, on the combustion process of coal particles were explored. It was found that, the location of reaction zones appears more upstream and the volatile matter concentration is higher for the cases with smaller particles. The combustion modes were examined. It was shown that the contribution of premixed combustion decreases with increasing particle size while non-premixed combustion prevails in all cases. The increase of particle mass loading results in an increase of volatile matter mass fraction, which leads to higher heat release rate and combustion temperature. Through Voronoï analysis, the preferential concentration of particles was examined. It was found that the preferential concentration behavior of particles is more prominent when the particle Stokes number (St) is close to unity. The volatile matter concentration is higher when particles are preferentially concentrated, facilitating coal particles to ignite.

Dynamic membrane interaction and amyloid fibril formation of glucagon, melittin and human calcitonin

Glucagon is a 29-amino acid peptide hormone secreted by pancreatic α-cells and interacts with specific receptors located in various organs. Glucagon tends to form gel-like fibril aggregates that are cytotoxic. It is important to reveal the glucagon-membrane interaction to understand activity and cytotoxicity of glucagon and glucagon oligomers. In this review, first glucagon-membrane interactions are described as morphological changes in dimyristoylphosphatidylcholine (DMPC) bilayers containing glucagon in acidic and neutral conditions as compared to the case of melittin. Second, fibril formation by glucagon in acidic solution is discussed in light of morphological and structural changes. Third, kinetic analysis of glucagon fibril formation was performed using a two-step autocatalytic reaction mechanism, as investigated in the case of human calcitonin. The first step is a nuclear formation, and the second step is an autocatalytic fibril elongation. Forth, fibril formation of glucagon inside glucagon-DMPC bilayers in neutral solution under near physiological condition is described.

Silicon-doped β-Ga2O3 films grown at 1 µm/h by suboxide molecular-beam epitaxy

We report the use of suboxide molecular-beam epitaxy (S-MBE) to grow β-Ga2O3 at a growth rate of ∼1 µm/h with control of the silicon doping concentration from 5 × 1016 to 1019 cm−3. In S-MBE, pre-oxidized gallium in the form of a molecular beam that is 99.98% Ga2O, i.e., gallium suboxide, is supplied. Directly supplying Ga2O to the growth surface bypasses the rate-limiting first step of the two-step reaction mechanism involved in the growth of β-Ga2O3 by conventional MBE. As a result, a growth rate of ∼1 µm/h is readily achieved at a relatively low growth temperature (Tsub ≈ 525 °C), resulting in films with high structural perfection and smooth surfaces (rms roughness of &amp;lt;2 nm on ∼1 µm thick films). Silicon-containing oxide sources (SiO and SiO2) producing an SiO suboxide molecular beam are used to dope the β-Ga2O3 layers. Temperature-dependent Hall effect measurements on a 1 µm thick film with a mobile carrier concentration of 2.7 × 1017 cm−3 reveal a room-temperature mobility of 124 cm2 V−1 s−1 that increases to 627 cm2 V−1 s−1 at 76 K; the silicon dopants are found to exhibit an activation energy of 27 meV. We also demonstrate working metal–semiconductor field-effect transistors made from these silicon-doped β-Ga2O3 films grown by S-MBE at growth rates of ∼1 µm/h.

One-Pot Syntheses of PET-Based Plasticizer and Tetramethyl Thiuram Monosulfide (TMTS) as Vulcanization Accelerator for Rubber Production

Styrene-butadiene (SBR) and acrylonitrile-butadiene (NBR) rubber blends with tetramethyl thiuram disulfide (TMTD) and tetramethyl thiuram monosulfide (TMTS) accelerators and environmentally friendly plasticizers, obtained from PET recycling and biobased resources (LA/PG/PET/EG/LA), were prepared. The mechanical properties of the obtained rubber products were tested and compared with those of commercial dioctyl terephthalate (DOTP). TMTS was prepared by simple and efficient one-pot synthesis from dimethylamine, carbon disulfide, potassium cyanide, and ammonium chloride as catalysts in recycled isopropanol/water azeotrope as solvent. In a comparative study, methoxide, ethoxide, iodide, and amide ions were also used. The two-step reaction mechanism of TMTS synthesis involves the oxidation of the amine salt of dimethyldithiocarbamic acid to TMTD by hydrogen peroxide and sulfur elimination from the TMTD disulfide bond. Potassium cyanide appears to be the most efficient nucleophile. The simplicity of operation, mild reaction conditions, solvent recycling, high yields, and applicability to the industrial level are the advantages of this process. Shore hardness, tensile strength, and compression test results of vulcanized blends before and after aging showed similar properties for both accelerators, while somewhat better results were obtained with LA/PG/PET/EG/LA plasticizer.

Insights into alloy/oxide or hydroxide interfaces in Ni-Mo-based electrocatalysts for hydrogen evolution under alkaline conditions.

Nickel-molybdenum (Ni-Mo) alloys are promising non-noble metal electrocatalysts for the hydrogen evolution reaction (HER) in alkaline water; however, the kinetic origins of their catalytic activities still remain under debate. In this perspective, we systematically summarize the structural characteristics of Ni-Mo-based electrocatalysts recently reported and find that highly active catalysts generally have alloy-oxide or alloy-hydroxide interface structures. Based on the two-step reaction mechanism under alkaline conditions, water dissociation to form adsorbed hydrogen and combination of adsorbed hydrogen into molecular hydrogen, we discuss in detail the relationship between the two types of interface structures obtained by different synthesis methods and their HER performance in Ni-Mo based catalysts. For the alloy-oxide interfaces, the Ni4Mo/MoO x composites produced by electrodeposition or hydrothermal combined with thermal reduction exhibit activities close to that of platinum. For only the alloy or oxide, their activities are significantly lower than that of composite structures, indicating the synergistic catalytic effect of binary components. For the alloy-hydroxide interfaces, the activity of the Ni x Mo y alloy with different Ni/Mo ratios is greatly improved by constructing heterostructures with hydroxides such as Ni(OH)2 or Co(OH)2. In particular, pure alloys obtained by metallurgy must be activated to produce a layer of mixed Ni(OH)2 and MoO x on the surface to achieve high activity. Therefore, the activity of Ni-Mo catalysts probably originates from the interfaces of alloy-oxide or alloy-hydroxide, in which the oxide or hydroxide promotes water dissociation and the alloy accelerates hydrogen combination. These new understandings will provide valuable guidance for the further exploration of advanced HER electrocatalysts.

Thermal safety of solid rocket motor with complex charge structure

This present work is focused to study thermal safety and heat transfer characteristics of large-scale solid rocket motor (SRM) with complex star-charged structure. Here, we have used three-dimensional unsteady heat transfer model coupled with a two-step global reaction mechanism of ammonium perchlorate/hydroxyl terminated polyether (AP/HTPE) propellant. Comparisons of the ignition delay time and temperature of computational results are done with experimental studies, and a reasonable match has been obtained in these comparisons. It is found that the heats transferred from the thermal environment and released from the exothermic reaction of the propellant jointly intensify the occurrence of the cook-off response of the SRM. The propellant at the bottom of the SRM can reach to a higher temperature over the time and thus the exothermic reaction is rapidly intensified with an increase of the propellant temperature, releasing more reaction heat simultaneously. The heat energy is gradually accumulated in the SRM and the propellant is eventually ignited under this high-heat environment. The ignition temperature of the SRM basically linearly increases with the AP content at 10.8% HTPE and the ignition temperature curve under different AP contents is closer to the quadratic curve at 7.8% HTPE. Also, the content of HTPE mainly has a certain effect on the ignition time that is 288 s and 283 s with its content of 7.8% and 10.8%, respectively. The heat transfer rate and the case temperature of the SRM are all increasing with an increase of environmental temperature, while the depth of the heat transfer is decreasing. Further, the ignition delay time can be expressed on environmental temperature as: ti = 2.073263exp11 × Te-2.89.