Activation Energy Of Decomposition Research Articles

Valorization of Microcrystalline Cellulose Using Heterogeneous Protonated Zeolite Catalyst: An Experimental and Kinetics Approach

This study aimed to valorize microcrystalline cellulose (MCC) using protonated zeolite catalysts such as (H-ZSM-5) and Cr/H-ZSM-5 (5%) in ionic liquid. The catalytic effect in synergy with 1-butyl-3-methylimidazolium Chloride ([BMIM] Cl) ionic liquid was studied in detail. The total reducing sugar (TRS) was determined using the 3, 5-dinitrisalcylic acid (DNS) array method. The catalysts were characterized using techniques such as Fourier transform infrared (FT-IR), X-ray diffraction analysis (XRD), temperature-programmed desorption of ammonia (NH3-TPD), and BET-surface area analyzer. H-ZSM-5 effectively depolymerized cellulose with a maximum yield of 70% total reducing sugar (34% glucose, 8% fructose, and 4.5% 5-HMF). Cr/H-ZSM-5 catalyst dehydrated fructose to 5-HMF with a yield of 53%. The use of ionic liquid significantly reduced the activation energy of formation and decomposition. The activation energy determined in cellulose hydrolysis was 85.83 KJ mol−1 for a reaction time of 180 min while the decomposition energy was found to be 42.5 kJ mol−1.

Kinetic Analysis of the Generation of Active Sites During the Low-Temperature Pyrolysis of Coal

ABSTRACT Decomposition of oxygen-containing functional groups simultaneously produces CO and CO2, accompanied by the generation of active sites. Two different methods were applied in the study to speculate the kinetics of gas generation and the formation of active sites in coal pyrolysis. The evolution of CO and CO2 gas generation during isothermal pyrolysis under different temperatures was first analyzed, and the generation of CO and CO2 in the pyrolysis process was divided into three stages: the rapid decline stage, slow decline stage, and stabilization stage. In the early stage of the pyrolysis reaction, functional groups exhibited a rapid decomposition rate and a high conversion rate (), which rapidly decreased the gas concentrations. With increasing pyrolysis time, the decomposition of functional groups declined with a low conversion rate () and showed a steady reaction rate in the later stage. On this basis, a method to calculate the activation energy during pyrolysis based on the data of gases generated in a steady period with a continuous cooling temperature was proposed. Activation energies of 70.12–148.39 kJ/mol for the CO formation and 64.47–127.38 kJ/mol for the CO2 formation were obtained from four different coals. In addition, a thermogravimetric analyzer was used to explore the apparent activation energies in the decomposition process via Coats-Redfern (C-R) method; activation energies of 39.33–126.65 kJ/mol and pre-exponential factors of 1.31–5.15E+08 s−1 were obtained for different coals. The results revealed that the CO had a greater generation activation energy than CO2, and a higher metamorphism degree implies a higher decomposition activation energy, which indicates that the decomposition of carboxyl groups and low-rank coals result in higher active sites.

Nitrogen-rich energetic polymer powered aluminum particles with enhanced reactivity and energy content

Aluminum particles are of significant interest in enhancing the energy release performance of explosives. One of the major impediments to their use is that Al2O3 shell significantly decreases overall performance. To address this issue, we investigate creating aluminum particles with a glycidyl azide polymer (GAP) coating to improve their reactivity while retaining their energy content. We found that the aluminum particles were coated with a GAP layer of thickness around 8.5 nm. The coated aluminum particles were compared to non-coated powder by the corresponding reactivity parameters obtained from simultaneous differential scanning calorimetry, thermal gravimetric analysis, coupled with mass spectral and infrared spectral analyses. Besides, the comparison on the energy content was also conducted based on P–t tests and a laser-induced air shock from energetic materials (LASEM) technique. It was found that GAP shifted the oxidation onset of aluminum particles to a lower temperature by ~ 10 °C. Besides, the oxidation activation energy of aluminum particles was also reduced by ~ 15 kJ mol−1. In return, aluminum particles reduced the activation energy of the second stage decomposition of the GAP by 276 kJ mol−1. And due to the synergistic effect between aluminum and GAP, the decomposition products of GAP were prone to be oxycarbide species rather than carbonitride species. In addition, the P–t test showed the peak pressure and pressurization rate of GAP coated aluminum particles were separately 1.4 times and 1.9 times as large as those of non-coated aluminum particles. Furthermore, the LASEM experiment suggested the shock wave velocity of the GAP coated aluminum particles was larger than that of non-coated aluminum particles, and the largest velocity difference for them could be 0.6 km s−1. This study suggests after coating by GAP, the aluminum particles possess enhanced reaction performance, which shows potential application value in the fields of aluminized explosives and other energetic fields.

Synthesis of Cinnamoyl‐Amino Acid Ester Derivatives and Structure‐Activity Relationship Based on Thermal Stability, Dielectric, and Theoretical Analysis

AbstractIn this study, cinnamic acid derivatives were synthesized from the reaction of benzaldehyde derivatives with malonic acid in the presence of pyridine and piperidine. These compounds were then respectively reacted with glycine and L‐alanine methyl ester hydrochloride based on triazine methodology to obtain novel cinnamoyl‐amino acid ester derivatives. The structure of these compounds were established via 1H, 13C APT, FT‐IR, MS and elemental analysis. The synthesized novel compounds were studied in terms of structure‐activity relationship based on dielectric, thermal stability, and theoretical analysis. Dielectric analysis was carried out in terms of amino acid type and aromatic substituted group (electron‐withdrawing or releasing group factor). Amino acid side chain differences make alanine conjugates have higher ϵ′ values compared to glycine conjugates. Thermal stability analysis was performed for the compounds (10 and 16) with the highest dielectric constants. Thermal decomposition activation energies were calculated as 95 kJ mol−1 and 100 kJ mol−1 for 10 and 16, respectively. HOMO‐LUMO energy levels and other related properties of the target compounds were analyzed and a correlation was observed between HOMO‐LUMO energy band gap and dielectric constant.

Theoretical Study on the Electrochemical Catalytic Activity of Au-Doped Pt Electrode for Nitrogen Monoxide

In order to gradually reduce automobile exhaust pollution and improve fuel quality, the NOx sensor, which can be monitored in real time in an automobile engine’s electronic control system, has become an indispensable part of the automobile lean burn system. In these types of NOx sensors, Au-doped platinum electrodes have received great attention due to their selectivity towards NO. However, the reaction process of NO gas on the Au-doped platinum electrode in the sensor and the possible regulation mechanism is still unclear. In this paper, the density functional theory (DFT) was used to analyze the effect of Au-doped Pt electrodes on the performance of nitrogen oxide sensors in automobiles. Firstly, the adsorption energies of NO molecules on pure Pt and Au/Pt surfaces were compared. The adsorption and dissociation of NO on Pt substrates doped with Au monomers, dimers, and trimers were investigated. These results showed that Au can effectively weaken the adsorption energy of NO molecules on a Pt surface. It was noted that with the increase in the number of Au atoms on the surface of Pt(111), the adsorption capacity of NO molecules on the alloy surface becomes weaker. When observing the transition state of NO decomposition on three different alloy surfaces, the study showed that the activation energy and reaction heat of NO dissociation increased. It further showed that doping with Au increased the activation energy of NO decomposition, thereby effectively inhibiting the decomposition of NO.

Microwave-Assisted Synthesis of the Flexible Iron-based MIL-88B Metal–Organic Framework for Advanced Energetic Systems

The 3D metal–organic framework (MOF), MIL-88B, built from the trivalent metal ions and the ditopic 1,4-Benzene dicarboxylic acid linker (H2BDC), distinguishes itself from the other MOFs for its flexibility and high thermal stability. MIL-88B was synthesized by a rapid microwave-assisted solvothermal method at high power (850 W). The iron-based MIL-88B [Fe3.O.Cl.(O2C–C6H4–CO2)3] exposed oxygen and iron content of 29% and 24%, respectively, which offers unique properties as an oxygen-rich catalyst for energetic systems. Upon dispersion in an organic solvent and integration into ammonium perchlorate (AP) (the universal oxidizer for energetic systems), the dispersion of the MOF particles into the AP energetic matrix was uniform (investigated via elemental mapping using an EDX detector). Therefore, MIL-88B(Fe) could probe AP decomposition with the exclusive formation of mono-dispersed Fe2O3 nanocatalyst during the AP decomposition. The evolved nanocatalyst can offer superior combustion characteristics. XRD pattern for the MIL-88B(Fe) framework TGA residuals confirmed the formation of α-Fe2O3 nanocatalyst as a final product. The catalytic efficiency of MIL-88B(Fe) on AP thermal behavior was assessed via DSC and TGA. AP solely demonstrated a decomposition enthalpy of 733 J g−1, while AP/MIL-88B(Fe) showed a 66% higher decomposition enthalpy of 1218 J g−1; the main exothermic decomposition temperature was decreased by 71 °C. Besides, MIL-88B(Fe) resulted in a decrease in AP decomposition activation energy by 23% and 25% using Kissinger and Kissinger–Akahira–Sunose (KAS) models, respectively.

Thermal Decomposition Mechanism of Molecular Perovskite Energetic Material (C6NH14)(NH4)(ClO4)3(DAP‐4)

AbstractThe recently developed ammonium perchlorate‐based molecular perovskite has been demonstrated to exhibit excellent comprehensive performance as an energetic material. This ABX3‐type molecular perovskite energetic material consists of a high symmetry ternary structure framework stabilized through ionic bonds. In this work, the thermal decomposition mechanism of (C6NH14)(NH4)(ClO4)3 (DAP‐4) was extrapolated by analyzing its thermal decomposition characteristics, gas products, kinetic parameters, and condensed phase change results along with temperature‐varying, with the help of DSC‐TG‐MS‐FTIR and in‐situ FTIR experiment. The results show that a rapid reaction occurs once the decomposition of DAP‐4 starts at 383.7 °C, with the maximum thermal weight loss rate reaches 97.4 %. By using Kissinger's and Ozawa's method, the calculated activation energy of thermal decomposition of DAP‐4 was estimated to be 124.3 kJ/mol and 128.6 kJ/mol, respectively, demonstrating good reliability of our results. The gas products during the thermal decomposition were found mainly include NH3, H2O, HNCO, HCN, CO, HCl, and CO2. The decomposition process of DAP‐4 contains three stages. The first stage involves crystal form changes and H+ transfer of DPA‐4, followed by the collapse of the cage skeleton in the second stage. The third stage mainly involves a rapid redox reaction at high temperatures to generate great heat.

Component regulation in novel La-Co-O-C composite catalyst for boosted redox reactions and enhanced thermal stability in methane combustion

A novel La-Co-O-C (LC-C) composites were prepared via a facile co-hydrothermal route with oxides and glycerol and further optimized for methane catalytic activity and thermal stability via component regulation. It was demonstrated that Co3O4 phase was the main component in regulation. The combined results of X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption of oxygen (O2-TPD), temperature-programmed reduction of hydrogen (H2-TPR), temperature-programmed desorption of ammonia/carbon dioxide (NH3/CO2-TPD) revealed that component regulation led to more oxygen vacancies and exposure of surface Co2+, lower surface basicity and optimized acidity, which were beneficial for adsorption of active oxygen species and activation of methane molecules, resulting in the excellent catalytic oxidation performance. Especially, the (3.5)LC-C (3.5 is Co-to-La molar ratio) showed the optimum activity and the T50 and T90 (the temperature at which the CH4 conversion rate was 50% and 90%, respectively) were 318 and 367°C, respectively. Using theoretical calculations and in situ diffuse reflection infrared Fourier transform spectroscopy characterization, it was also found that the catalytic mechanism changes from the “Rideal-Eley” mechanism to the “Two-term” mechanism depending on the temperature windows in which the reaction takes place. Besides, the use of the “Flynn-Wall-Ozawa” model in thermoanalytical kinetics revealed that component regulation simultaneously optimized the decomposition activation energy, further expanding the application scope of carbon-containing composites.

Material-scale flammability characteristics of epoxy-based coating systems

Flammability of intumescent coatings at the materials-scale is “expected” to have an impact on their fire resistance offered to the steel member. However, to what extent and at what stage during the exposure to an imposed fire curve in a furnace are not thoroughly established. The role of different functionality of the flame-retardant additives in this process is also not clear despite a thorough understanding of their thermal decomposition mechanisms. In an effort to better understand some of these aspects, in this work, model systems based on different flame-retardant additives in epoxy are chosen to cover various strategies (like intumescent, radical quenching, and endothermic behavior) that are typically employed to reduce the flammability of a coating system. The flame-retardant additives chosen are ammonium polyphosphate, tetrabromobisphenol-A, 9,10-dihydro-9-oxa-10-phosphaphenanthrene oxide, and aluminum trihydroxide. The effects of flame-retardant additives on the curing, thermal decomposition, and flammability of epoxy resin are investigated. Reactive flame-retardant additives, in particular, are found to reduce the enthalpy associated with curing of epoxy by more than 45%. However, as the amount of hardener incorporated in these formulations is not controlled despite the presence of reactive flame-retardant additives, this had a negative effect on the thermal decomposition behavior of the epoxy/flame-retardant formulations, and consequently on the calculated decomposition activation energies. Heating rate seems to be a dominating parameter influencing the flammability of the formulations. Peak heat release rate values, irrespective of the formulation, increased by more than 1382%–1970% by changing the heating rate in a pyrolysis flow combustion calorimeter from 6°C/min to 100°C/min. As the flammable volatiles released per unit time are higher at high heating rates, ignition and subsequent flaming of the coating occurred in the furnace tests, where a cellulosic fire curve was simulated. This has significantly influenced the fire resistance times.

Thermal, Optical, and Color Modification in Makrofol VLG 7-1 Nuclear Track Detector Due to Gamma Irradiation

Makrofol VLG 7-1 is a sort of Makrofol (bisphenol-A polycarbonate) nuclear track detector. We believe that the current study is the first one that deals with the effect of γ-ray irradiation on Makrofol VLG 7-1. Samples of Makrofol films were treated with various γ-ray dosages (20–140 kGy). The resultant outcome of the γ-ray irradiation on the thermal and optical characteristics of the Makrofol samples were explored applying thermogravimetric analysis (TGA) and ultraviolet spectroscopy (UVs). The degradation temperature, activation energy of thermal decomposition, optical band gap, refractive index, Urbach energy, and optical dielectric parameters were characterized and interpreted based on the γ-ray dosage. The optical bandgap dropped from 4.26 to 4.14 eV for a γ-ray dosage of 140 kGy, accompanied with a rise in both Urbach energy and thermostability of the samples. We attribute this to the dominance of crosslinking. Additionally, the color differences between the pristine and the irradiated samples were characterized. The pristine Makrofol was uncolored. It exhibited noteworthy color changes during the γ-ray treatment, as the color intensity reached a value greater than 5. This is an acceptable match in commercial reproduction on printing presses.

Synthesis of Moringa oleifera coated silver-containing nanocomposites of a new methacrylate polymer having pendant fluoroarylketone by hydrothermal technique and investigation of thermal, optical, dielectric and biological properties

Firstly, silver nanoparticles were synthesized by green synthesis method from Moringa oleifera extract. Nanocomposites containing newly synthesized methacrylate polymer, poly 2-(4-fluorophenyl)-2-oxoethyl-2-methylprop-2-enoate (PFPAMA) and Ag nanoparticles from M. oleifera in different mass ratios (1, 3, and 5 wt%) were synthesized using the hydrothermal method. The morphological and structural properties of the materials have been examined by SEM, FTIR, UV, TGA, and XRD techniques. The activation energies (Ea ) related to thermal decomposition of the nanocomposites were estimated by the Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose methods by using non-isothermal TGA experiments. The thermal stability, glass transition temperature (Tg ), and the thermal decomposition activation energy (Ea ) values of nanocomposites were increased by increasing the Ag nanoparticles amount on the composite. The dielectric constant (ε′), the dielectric loss factor (ε″) and ac conductivity of neat PFPAMA and nanocomposites were also measured for the frequency range of 100 Hz to 2 kHz at 25 °C. It was seen that the frequency dependence of the dielectric constant and dielectric loss factor decreased with increasing frequency. The biological activities of nanocomposites against gram-positive (Staphylococcus aureus), gram-negative (Escherichia coli) bacteria and Candida krusei yeast were also tested. The antibacterial effect increased against both bacterial species as the amount of Ag nanoparticles from M. oleifera in the nanocomposites increased. In addition, the wound healing properties of nanocomposites were investigated by the scratch wound test.

A high energy density 3D nano-carbon based magnesium hydroxide reversible chemical reaction heat storage material synthesis and heat transfer performance investigation

Magnesium hydroxide composite chemical heat storage materials were constructed with in-situ prepared 3D-Graphene. Mg(OH)2 particles were anchored onto the surface of the nanosupport by deposition-precipitation method. According to the heat transfer numerical simulation, addition of 3D-Graphene could greatly change the temperature distribution in the reactor and was easier to export thermal energy to the outside thermal load side. This energy storage system could output thermal energy at around 200 °C and absorbed heat at the range of 300–400 °C. Transmission electron microscopy result indicated that the particle size of Mg(OH)2 was primarily in the range of 20–50 nm. X-ray diffraction characterization showed that the magnesium hydroxide was well dispersed in the composite material. This material provided an obviously enhanced heat storage density (610 kJ/kg), no distinct attenuation and greatly improved hydration rate compared with those of magnesium oxide because of hydrogen bonding effect in composite materials. 3D-Graphene lead to obvious decomposition activation energy decreasing of Mg(OH)2 that would improve its utilization in the heat storage process. This was probably due to its surface effect. 3D-Graphene/Mg(OH)2-1 showed the lowest activation energy (116.7 kJ/mol), The thermal conductivity of the composite material was 9.4 times higher than that of Mg(OH)2 as a result of the addition of 3D-Graphene. The proposed method provided a facile and valid technique for thermal energy utilization and the synthesis of nano-composed materials with enhanced chemical heat storage performance.

An Electrochemical Study of Gold Dissolution in Thiosulfate Solution with Cobalt–Ammonia Catalysis

Alkali agents could be used to enhance the extraction of zinc from solution, but excess alkali can lead to emulsification of the solution. In this study, the redox couples of Co(III)/Co(II) could be formed based on the thermodynamic analysis, and catalyze the dissolution of gold in a cobalt–ammonia–thiosulfate system. The catalytic mechanism of cobalt–ammonia for gold dissolution in the thiosulfate solution was further proposed by the analysis of polarization curves to be that NH3 catalyzes the dissolution of gold in the anodic area, and Co(NH3)63+ catalyzes the reduction of dissolved oxygen in the cathodic area. In the dissolution of gold, the concentration of NH3, Co3+ and S2O32− increased, and the dissolution of gold increased. The apparent activation energy for gold dissolution is 41.15 kJ/mol in a temperature range of 25–40 °C, and this demonstrates that gold dissolution is chemically controlled. The SEM-EDS and XPS analyses indicate that the precipitate coating on gold surfaces is mainly S2− in CoS and S8. The decomposition of thiosulfate was also carried out in different thiosulfate solutions. Results have shown that the increase of NH3 concentration can reduce thiosulfate decomposition, while the increase of Co3+ and S2O32− concentration can accelerate thiosulfate decomposition. The apparent activation energy for thiosulfate decomposition with the temperature range of 26.6–41 °C is determined to be 22.12 kJ/mol, which shows that thiosulfate decomposition is mixed chemical-diffusion-controlled.

Stability, reactivity and decomposition kinetics of surface passivated α-AlH3 crystals

As a novel high energy fuel, aluminum hydride (AlH3) has great potential in the field of solid propellants because of its high hydrogen capacity, which can significantly improve the specific impulse of solid propellants. In order to improve the stability of α-AlH3, hydrochloric acid has been used to stabilize AlH3 and the stabilization mechanism has been investigated. Various characterization techniques including scanning electron microscopy, X-ray electron spectrometer, X-ray diffraction, thermal analysis, and vacuum stability test have been employed to investigate the morphology, crystal structure, thermal stability, and decomposition kinetics of raw and passivated α-AlH3. The results showed that the honeycomb-like structures could be formed on the surface of α-AlH3 after passivation. First of all, the initial decomposition temperatures of the passivated samples were slightly increased. In particular, for the optimized sample with 105 min passivation time (AlH3-105min), the initial decomposition temperature (173.4 °C) is increased by 5.6 °C. Moreover, the total decomposition time (1652 min) is improved by about 50% than that of the raw sample (1098 min). Besides, the decomposition activation energies (Ea) of passivated samples are much higher than that of the raw sample (84.8 kJ mol−1), in which the optimized sample (AlH3-105min) reaches 107.1 kJ. mol−1. The decomposition kinetics model may change from 3-D nucleation and nucleus growth model to 2-D nucleation and nucleus growth model. It demonstrates the passivated samples have a lower decomposition rate and higher thermal stability. The stabilization mechanism is as follows: removing the impurities on the surface and accelerating the hydrolysis reaction of AlH3 to generate complete and dense oxide layers.

Property Prediction of Ag-Filled Isotropic Conductive Adhesive through the Analysis of Its Curing and Decomposition Kinetics

In this study, various thermal analyses were carried out on a self-developed and commerce-oriented Ag-filled isotropic conductive adhesive (ICA) and its unfilled matrix resin through which glass transition temperature (Tg) and thermal endurance could be quantitatively predicted. An autocatalyzed kinetic model was used to describe the curing reaction, which was proven to be in good consistency with the experimental data. The activation energies for the curing reaction of the ICA and the matrix resin were determined to be 68.1 kJ/mol and 72.9 kJ/mol, respectively, which means that the reaction of the ICA was easier to occur than its unfilled matrix resin. As a result, the time–temperature profile could be calculated for any Tg requested based on the kinetic model of curing and the DiBenedetto equation. Further, the thermal decomposition stability of the ICA and its unfilled matrix resin were also studied. The activation energies for the thermal decomposition of the ICA and the matrix resin were calculated to be 134.1 kJ/mol and 152.7 kJ/mol, respectively, using the Ozawa–Flynn–Wall method, which means that the decomposition of ICA was easier to occur. The service life of the resin system at a specific temperature could therefore be calculated with their activation energy. The addition of micro-scale Ag flakes did not change the curing and decomposition mechanisms by much.

Determination of the Activation Energy for Hydride Decomposition Using a Sieverts-Type Apparatus and the Kissinger Equation

We developed a method to determine the activation energy for hydride decomposition using a Sieverts-type apparatus and the Kissinger equation, not using thermal analysis methods. The quantity of hydrogen released from the sample and the temperature of the reactor were first measured as a function of time at different heating rates (Φ) in a Sieverts-type apparatus. The dehydriding rates were calculated according to time and the temperature Tm (at which the dehydriding rate was the highest). Φ and Tm were then applied to the Kissinger equation. The dehydriding rate of Mg-5Ni samples obeyed a first-order law, and the Kissinger equation could thus be used to determine the activation energy. On a heating rate of 3 K/min, the decomposition rate of hydride was the highest at 590.0 K. From a plot of ln (Φ/Tm2) versus 1/Tm, the obtained activation energy for hydride decomposition was 174 kJ/mole.

Decomposition Kinetics and Cook-Off Numerical Simulation of Insensitive Energetic Plasticizer Plasticized Propellants

Aiming at the thermal safety issues between the insensitive energetic plasticizer and propellant components, NG/BTTN and insensitive energetic plasticizer BuNENA plasticized propellant was compared by DSC test and cook-off numerical simulation, with the thermal safety property evaluated. The decomposition activation energy Ea and self-ignition temperature Tb of BuNENA plasticized propellant was lower than that of NG/BTTN plasticized propellant. Two kinds of propellant responded in the central area during slow cook-off simulation while in the near shell area during medium cook-off simulation. During fast cook-off simulation, depending on the different thickness of insulator, propellant responded at the area near shell or the area near the caps. The response temperature of two propellants in cook-off simulation agreed with decomposition and self-ignition temperature by DSC, and the decomposition of plasticizer could trigger the response. In cook-off simulation, BuNENA plasticized propellant showed a lower response temperature with a smaller high temperature area before response, resulting a milder response and better thermal safety than NG/BTTN plasticized propellant.

Fluorinated Phthalonitrile Resin with Excellent Thermal Stability and Low Dielectric Constant for High‐Frequency Electronic Packaging

AbstractPhthalonitrile (PN) resin promising material for preparing high‐speed and high‐frequency electronic packaging because of its unique hightemperature resistance and excellent insulation performance. A fluorinated PN oligomer (4,4’‐bis (p‐perfluoro‐phenol‐(bis(p‐phenol)perflouoropropane‐2,2‐diyl)‐p‐oxy‐diphthalonitrile) (PFDP)) containing trifluoromethyl and decafluorobiphenyl groups are designed, synthesized, and characterized. The oligomer is blended with 4‐(aminophenoxy) phthalonitrile (APPH), and then cured into polymers under the temperature‐programmed process. The reactive blend has good processability, and structures of isoindole, triazine ring, and phthalocyanine ring are found in the curing reactions. The fluorinated PN (P‐380) shows outstanding thermal stability and mechanical properties (5% thermal degradation temperature: 518 °C (N2); 516 (Air), THeat‐resistance index: 268 °C, activation energy of thermal decomposition: 334.89 kJ mol−1, glass transition temperature (Tg) > 400 °C). Meanwhile, the fluorinated PN simultaneously exhibited a superior low dielectric constant (Dk, 2.21) and dielectric loss (Df, 0.01) at 10 GHz. Moreover, the water absorption of the resin is as low as 0.74%, which meets the requirement of dielectric materials. These results would strongly suggest such PFDP PN resin as excellent packaging materials in those high‐tech applications such as aerospace and communication electronic devices.

Study on Autocatalytic Decomposition of Dimethyl Sulfoxide (DMSO) III: Investigations Regarding the Main Decomposition

It is important to know the entire decomposition mechanism of energetic materials for safety purposes, such as the assessment, control, mitigation, and prevention of thermal hazards. Dimethyl sulfoxide (DMSO) is a common solvent that is widely used in laboratories and industrial applications; however, several severe incidents due to its decomposition have been reported. The decomposition mechanism of DMSO has been studied for several years; however, it has not been sufficiently clear until now. To elucidate the complicated decomposition pathway, analyses of materials from DMSO decomposition were conducted. Several new chemical bonds were found in the decomposition products through gas chromatography–mass spectrometry (GC-MS) analysis, which suggests a radical reaction. Atomic sulfur S(0) or organic divalent sulfur S(II) was found on the inner wall of the vessel after decomposition, which indicates that the sulfur atom in DMSO was reduced during decomposition. In addition to the chemical analyses, a kinetic study was carried out for the data obtained through isothermal heating tests. All of the DMSO samples with or without the studied impurities showed similar activation energies for the main decomposition. Autocatalysts in DMSO decomposition are proposed to work not by accelerating the main decomposition but rather by shortening the induction period. It is proposed that the main decomposition of DMSO occurs via a radical pathway.

Gamma irradiation effects on styrene butadiene rubber/Pb3O4: Mechanical, thermal, electrical investigations and shielding parameter measurements

Polymer composites of Styrene-Butadiene Rubber SBR filled with Pb3O4 have been prepared with different concentrations ranging between (4.5–37.8 wt%). The linear μ and mass attenuation coefficients μm of all samples have been investigated at energies 1173, 1333 and 662 KeV from 60Co and 137Cs point sources, and results were compared with the calculated one via WinXcom at the same photon energies, it was clear that μm increases in proportion to the concentration of filler. The radiation protection efficiency RPE% increased with increasing filler concentration while HVL (half-value layer) and TVL (tenth value layer) were decreased with increasing filler concentration; also, atomic effective number Zeff has computed. Activation energy of decomposition was calculated for samples that ranged from (190.71–225.74 J/K.mol), and kinetic parameters for thermal degradation of the SBR/Pb3O4 have been tabulated. The samples were irradiated with doses (50,100,150 and 200 kGy), mechanical properties have been carried out such as tensile strength, hardness (shore A) and elastic modulus, all showed improvement with irradiation doses up to 100 kGy except elongation at break decreased with increasing filler content. Electrical properties have been measured for the samples at room temperature to identify the conduction mechanism, which showed the applicability of Schottky-Richardson mechanism. The hopping distance of the charge carrier has been determined theoretically, ranging between (3 × 10−8 -1.43 × 10−8 m). Also, the dispersion and morphological analysis of composites have been studied using the Scanning Electron Microscope. The composites showed good performance as light-shielding material for low energies up to 300 KeV, where RPE% increased by increasing Pb3O4 concentrations from 8% (SBR1) to reach 46% (SBR5) at 662 KeV; similarly, the HVL decreased by 64% from (SBR1) to (SBR5).