Reaction Kinetics Of Thermal Decomposition Research Articles

Thermal degradation assessment, impact strength, and hardness of combination epoxy and polystyrene powder composite

The present study investigates the reactions of polystyrene and epoxy/polystyrene powder composites, exploring different weight percentages (8%, 12%, and 16%) of polystyrene during decomposition under highly elevated temperatures within a nitrogen atmosphere. The findings reveal that polystyrene content significantly influences the thermal behavior of pure epoxy, with a higher polystyrene content correlating with the increased thermal stability of the composites. This study observed a three-stage mass loss process by examining the reaction kinetics of thermal decomposition using the Coats-Redfern approach. Initially, weight reduction occurs due to moisture and volatile elimination, followed by a smooth mass loss phase attributed to weaker polymer chain linkages and, ultimately, char formation. Chemical kinetic parameters, such as activation energy and frequency factor, were successfully determined using the Coats-Redfern approach, with a first-order reaction observed across all data points, demonstrating a high R-square mean value of 99.8%. Differential scanning calorimetry (DSC) and thermal gravitational analysis (TGA) analyses revealed an increase in glass temperature from 86.95 to 92.85 °C and an elevation in activation energy from 75.38 to 92.85 kJ/mol with increasing polystyrene content (0–16 wt%). Furthermore, the study investigated the influence of thermodynamic parameters. In terms of mechanical properties, increasing polystyrene content reduced impact strength (from 8.5 to 4.23 Kj/m2). In contrast, hardness increased from 77.5 for pure epoxy to 80.4 at 12 wt% polystyrene content in the composite. These findings underscore the importance of thermal stability results in developing a comprehensive understanding of thermal decomposition processes, informing future research endeavors and industrial applications.

Isoconversional thermal decomposition reaction kinetics of oil palm trunk and rubberwood sawdust for thermochemical conversion processes.

Biomass as a raw material has profound implications for thermal conversion processes. It is important to study the relationship between kinetic modeling to depict significant importance in thermal processing by estimating volatile yield and reaction performance during biomass decomposition. This work aimed to determine the thermal decomposition reaction kinetics of non-woody (oil palm trunk (OPT)) and woody (rubberwood sawdust (RWS)) biomass. Devolatilization of biomass is determined by the thermogravimetric analysis (TGA) at three different heating rates (10, 20, and 30 °C/min) using nitrogen as inert gas. The kinetic analysis used isoconversion models of Friedman, Ozawa-Flynn-Wall (OFW), and Kissinger-Akahira-Sunose (KAS). The activation energy varied from 218.4 to 303.8 kJ/mol (Friedman), 235.9 to 299.1 kJ/mol (OFW), and 235.8 to 298.9 kJ/mol (KAS) for OPT; and 199.7 to 228.1 kJ/mol (Friedman), 210.6 to 225.6 kJ/mol (OFW), and 210.7 to 225.2 kJ/mol (KAS) for RWS. The kinetic analysis indicated that RWS and OPT had diverse reaction kinetics, which depend on the reaction rate and order of the reaction. Experimental and theoretical conversion data agreed reasonably well, indicating that these results can be used for future OPT and RWS process modeling. Consistency of results is validated using GC-MS equipped with a pyrolyzer.

Dual influence of nano barium oxide on thermal decomposition reaction kinetics and chemical stability of cellulose nitrate

This study explores the critical area of understanding how nanosized barium oxide (BaO) influences both the thermal decomposition reaction kinetics and chemical stability of nitrocellulose. To investigate this, BaO nanoparticles (NPs) were synthesized through the precipitation method and combined with nitrocellulose (NC). The prepared barium oxide NPs and NC-based composites were rigorously characterized using spectroscopic, microscopic and thermal analysis tools. To understand the thermal decomposition reaction kinetics of the NC-based composite, differential scanning calorimetry tests were conducted in association with various isoconversional kinetic approaches, such as the iterative Kissinger–Akahira–Sunose, iterative Flynn–Wall–Ozawa, and Vyazovkin's nonlinear integral with compensation effect (VYA/CE) methods. The impact of BaO NPs on the chemical stability of NC was investigated through qualitative and quantitative stability tests. The results of the thermal kinetic investigation and stability tests revealed an enhancement in the thermal and chemical stabilities of nitrocellulose with the addition of nano barium oxide.

Thermal decomposition reaction kinetics and storage life prediction of polyacrylate pressure-sensitive adhesive

Abstract The thermal decomposition behavior of polyacrylate pressure-sensitive adhesive (PSA) at heating rates of 4, 6, 8, and 10 K·min−1 was measured by thermogravimetric analysis (TGA). The kinetic parameters for thermal decomposition reaction of the polyacrylate adhesive were obtained from TG profile by differential method and integral method (Kissinger, general integral, MacCallum–Tanner, Šatava–Šesták, Agrawal, and Flynn–Wall–Ozawa), the results show that the main decomposition stage of the polyacrylate adhesive starts at 301°C and its activation energy is 142.68 kJ·mol−1, the pre exponential factor is 109.55, the decomposition mechanism obeys Avrami–Erofeev equation and its decomposition kinetic equation can be expressed as: dα/dT = (109.55/β)[(1 − α)/2][−ln(1 − α)]−1exp(−1.7161 × 104/T). The storage life of PSA at 25°C was predicted to be about 19 years by isoconversional method.

Hydrogen bond networks enhance the safety of energetic salts azobistetrazole-1,1′-dioxy dimethylbiguanide

Weak interaction is an important force widely existing in material molecules, which may affect the structure and even properties of materials, mainly including π stacking, hydrogen bond network and van der Waals force, etc. The π-stacking and hydrogen bonding networks in energetic materials have a particularly significant impact on their safety. 1,1′-dihydroxy-azobistetrazole (H2AzTO) with abundant hydrogen bond acceptor and dimethyl biguanide (DMG) with abundant hydrogen bond donor was selected as starting materials, then a new energetic salt with strong hydrogen bond network structure, azobistetrazole-1,1′-dioxy-dimethyl biguanide (DMGAzTO), was synthesized through an acid-base neutralization reaction. The structure of DMGAzTO was characterized by FT-IR, 1H NMR, 13C NMR, EA, and SC-XRD, and the thermal stability and non-isothermal thermal decomposition reaction kinetics of DMGAzTO were studied by DSC and TGA methods. The HOF, detonation velocity, and pressure (D, P) were calculated by Born-Haber cycle and K-J empirical formula. The friction and impact sensitivity (FS and IS) of the compound were examined using a BAM sensitivity tester. Results show that the DMGAzTO salt belongs to the 1:1 type with a molecule of bound water; the peak temperature of thermal decomposition is 502 K; the thermal weight loss rate is 82%; the theoretically calculated D and P are 8217 m s−1 and 27.1 GPa, and the FS and IS are 30 J and 360 N, respectively.

The fundamental studies on the reaction kinetics of thermal decomposition of bio-composite based backsheet materials in photovoltaic (PV) panel

This research presents the reaction kinetics of thermal decomposition of vetiver filled Polylactic Acid (PLA) bio-composite based backsheet in Photovoltaic (PV) panel via the Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The conventional PV backsheet called TEDLAR (Polyvinyl Fluoride, PVF) is made from petroleum, a non-biodegradable material which will impose serious problems to the environment at the end-of-life of the PV modules. Therefore, it is important to identify the suitability of PLA/vetiver to replace TEDLAR. The best composition of PLA/vetiver producing the lowest thermal degradation is discussed by analysing the activation energy of the bio-composites with different weight percent (wt. %) of PLA/vetiver. The result showed the wt. % of PLA/vetiver with lower content of the natural fibre has a lower thermal degradation temperature which indicates the rapid start of the degradation process. However, TEDLAR degrades at an average temperature of 400°C proving the ability to withstand extreme temperatures, thus it does not degrade easily. The results showed the higher the content of the vetiver, the lower the degradation temperature. The activation energy of the bio-composites was calculated using the Kissinger method and the estimation values of the different doses of PLA/vetiver range between 28 to 77 kJ/mol.

Synthesis, characterization, thermal behavior, and antitumor activities of an Ag(I) complex based on 4-(2-hydroxyphenyl)-2-methylpyrimidine

A new Ag(I) coordination complex, Ag(C11H10N2O)2·NO3 (C11H10N2O = 4-(2-hydroxyphenyl)-2-methylpyrimidine) is successfully synthesized and characterized by infrared spectroscopy, elemental analysis, and single-crystal X-ray diffraction analysis. This complex features a three-dimensional framework consisting of hydrogen bonds, π–π stacking interactions, coordination interactions, and electrostatic interactions. Moreover, the thermal stability and non-isothermal thermal decomposition reaction kinetics of the complex are well investigated by the methods of Kissinger and Ozawa. Finally, the antitumor ability of the complex is evaluated against human lung cancer cells (NCI-H460), human hepatocellular cancer cells (HepG2), and human breast cancer cells (MCF7). The complex exhibits potent antitumor activities against HepG2 and MCF7 cancer cells.

Raman and XRD study of polyhalite ore during calcinations

In this paper, the thermal decomposition of polyhalite ore from Dayantan Playa in Qaidam Basin of China was investigated by X-ray powder diffractometry (XRD), Raman spectroscopy (Raman), and thermal analysis techniques (TG-DTG). The dehydration reaction of polyhalite ore takes place with the release of water and starts at about 510 K. The results of X-ray diffraction of roasting sample showed that polyhalite ore starts to decompose into anhydrite and langbeinite at 573 K. Raman spectroscopy, in conjunction with X-ray diffraction, was also used to follow the thermal decomposition of polyhalite ore. The changes of internal models of vibration of the SO4 ions in sulfates indicated the phase transformation polyhalite, langbeinite, and anhydrite. The reaction kinetics of thermal decomposition of polyhalite ore were successfully modeled by a Coats-Redfern equation (lng(α)T2=lnARβE1−2RTE−ERT) and the activation energy is found to be 208 kJ·mol−1. Additionally, the effect of roasting temperature on potassium extraction from polyhalite ore was studied.

Research on the Thermal Decomposition Reaction Kinetics and Mechanism of Pyridinol-Blocked Isophorone Diisocyanate.

A series of pyridinol-blocked isophorone isocyanates, based on pyridinol including 2-hydroxypyridine, 3-hydroxypyridine, and 4-hydroxypyridine, was synthesized and characterized by 1H-NMR, 13C-NMR, and FTIR spectra. The deblocking temperature of blocked isocyanates was established by thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), and the CO2 evaluation method. The deblocking studies revealed that the deblocking temperature was increased with pyridinol nucleophilicity in this order: 3-hydroxypyridine > 4-hydroxypyridine > 2-hydroxypyridine. The thermal decomposition reaction of 4-hydroxypyridine blocked isophorone diisocyanate was studied by thermo-gravimetric analysis. The Friedman–Reich–Levi (FRL) equation, Flynn–Wall–Ozawa (FWO) equation, and Crane equation were utilized to analyze the thermal decomposition reaction kinetics. The activation energy calculated by FRL method and FWO method was 134.6 kJ·mol−1 and 126.2 kJ·mol−1, respectively. The most probable mechanism function calculated by the FWO method was the Jander equation. The reaction order was not an integer because of the complicated reactions of isocyanate.

The Thermo-Gravimetric Characteristics of the Waste Game Printed Circuit Board under Different Atmosphere

The printed circuit board (PCB) in the electronic waste contains a variety of metals and organic materials, including bromine, heavy metals and other pollutants. Thermal treatment is an effective method for harmless disposal of waste circuit boards with resources recycle. In this study, the composition of RF4 type waste game PCB was determined by elemental analysis and proximate analysis, followed by thermogravimetric analysis of the weight lost process in CO2、N2or air, at 10°C/min, 20°C/min or 30°C/min programmable heating rate, and the thermal decomposition reaction kinetics parameters were calculated with the Kissinger method. The results show that under the CO2atmosphere, the weight loss process of the sample consists of the 250°C～410°C and 750°C~960°C temperature intervals; under the N2atmosphere, the rapid weight loss stage is between 263°C and 420°C; under the air atmosphere, the weight loss process is from 178°C to 675°C, including three minor weight loss stages. The phenolic volatile components are mainly released around 260°C～360°C under three different atmospheres, while the residual carbon is further oxidized under the air atmosphere or gasified in CO2at temperatures above 800°C.

Synthesis and thermal behavior of 1,8-dihydroxy-4,5-dinitroanthraquinone manganese salt

A novel energetic combustion catalyst, 1,8-dihydroxy-4,5-dinitroanthraquinone manganese salt (DHDNEMn), was synthesized by virtue of the metathesis reaction in a yield of 91%, and its structure was characterized by IR, element analysis and differential scanning calorimetry(DSC). The thermal decomposition reaction kinetics was studied by means of different heating rate DSC. The results show that the apparent activation energy and pre-exponential factor of the exothermic decomposition reaction of DHDNEMn obtained by Kissinger’s method are 162.3 kJ/mol and 1011.8 s−1, respectively. The kinetic equation of major exothermic decomposition reaction of DHDNEMn is \(\frac{{d\alpha }} {{dT}} = \frac{{10^{11.8} }} {\beta }\frac{2} {5}(1 - \alpha )[ - \ln (1 - \alpha )]^{3/5} \exp ( - 1.623 \times 10^5 /RT) \). The entropy of activation(ΔS≠), enthalpy of activation(ΔH≠) and free energy of activation(ΔG≠) of the first thermal decomposition are −24.49 J·mol−1·K−1, 185.20 kJ/mol and 199.29 kJ/mol(T=575.5 K), respectively. The self-accelerating decomposition temperature(TSADT) and critical temperature of thermal explosion(Tb) are 562.9 and 580.0 K, respectively. The above-mentioned information on the thermal behavior is quite useful for analyzing and evaluating the stability and thermal safety of DHDNEMn.

Crystal structure and thermal behaviors for 3,5-dinitrobenzoic acid of 3,5-diamino-1,2,4-triazole

3,5-Dinitrobenzoic acid of 3,5-diamino-1,2,4-triazole (DAT) salt (DAT·DNBA) was synthesized and its structure was characterized by element analysis, IR and single-crystal X-ray diffraction analysis. The thermal behavior was investigated with the methods of differential scanning calorimetry (DSC) and rapid scan Fourier transform infrared spectroscopy (in situ thermolysis/RSFTIR), and the thermal decomposition reaction kinetics was obtained by means of DSC technique at the different heating rate. The results show that there are two mass loss stages at the thermal decomposition process, and the apparent activation energy and pre-exponential factor of the exothermic decomposition reaction of DAT·DNBA obtained by five integral methods (General integral, MacCallum–Tanner, Šatava–Šesták, Agrawal, Flynn–Wall–Ozawa) and one differential method (Kissinger) are 226.37kJmol−1 and 1014.51s−1 in the second decomposition stage. According to the change of the bond intensities, it can be deduced that hydronitrogen, oxynitride, and carbonitride should appear in the gaseous products breaking away from the condensed phase of DAT·DNBA. The groups of nitryl, amido and carboxyl have main contribution to some properties of the compound from the result of the quantum chemical calculation. The self-accelerating decomposition temperature (TSADT), thermal ignition temperature (TTIT) and the critical temperatures of thermal explosion (Tb) and the adiabatic time-to-explosion (tTIAD) is obtained as 660.25K, 677.16K, 691.70K and 236s, respectively. The detonation velocity (D) and pressure (p) were also estimated as 8358.86ms−1 and 30.19GPa. The above-mentioned information is quite useful for analysis and evaluating the stability and thermal safety of DAT·DNBA.

Thermal Behavior and Non-Isothermal Decomposition Reaction Kinetics of Aluminum Nanopowders Coated with an Oleic Acid/Hexogen Composite System

Aluminum nanopowders(nmAl)coated with oleic acid(OA)were obtained under nitrogen atmosphere,and their surface morphologies and structures were characterized by scanning electron microscope(SEM),X-ray diffraction(XRD),and Fourier transform infrared(FTIR)spectroscopy.The thermal decomposition reaction kinetics of composite systems,nmAl/hexogen(RDX)and(nmAl+OA)/RDX,were investigated using differential scanning calorimetry(DSC).Their kinetic parameters and kinetic equations were obtained.The results showed that most of the OA adsorbed on the aluminum nanopowder surface by physical adsorption.Only a small amount of OA reacted with the surface aluminum atoms and adhered to the surface via chemical bonds.Compared with the nmAl/RDX composite,the peak temperatures for the (nmAl+OA)/RDX composite at multiple heating rates were lower.The apparent activation energy(E a )and pre-exponential factor(A)of the main decomposition reaction were 141.18 kJ·mol -1 and 10 12.57 s -1 .The reaction mechanism fits a three-dimensional diffusion mechanism and obeys the Jander equation with n= 1/2.The kinetic equation can be expressed as:dα/dt=10 13.35 (1-α) 2/3 [1-(1-α) 1/3 ] 1/2 e -16981.0/T .

Thermal decomposition reaction kinetics of complexes of [Sm(o-MOBA)3bipy]2·H2O and [Sm(m-MOBA)3bipy]2·H2O

The complexes of [Sm(o-MOBA)3bipy]2·H2O and [Sm(m-MOBA)3bipy]2·H2O (o(m)-MOBA = o(m)-methoxybenzoic acid, bipy-2,2′-bipyridine) have been synthesized and characterized by elemental analysis, IR, UV, XRD and molar conductance, respectively. The thermal decomposition processes of the two complexes were studied by means of TG–DTG and IR techniques. The thermal decomposition kinetics of them were investigated from analysis of the TG and DTG curves by jointly using advanced double equal-double steps method and Starink method. The kinetic parameters (activation energy E and pre-exponential factor A) and thermodynamic parameters (ΔH ≠ , ΔG ≠ and ΔS ≠) of the second-step decomposition process for the two complexes were obtained, respectively.

Nonisothermal Thermal Decomposition Reaction Kinetics of Double-base Propellant Catalyzed with Lanthanum Citrate

The decomposition reaction kinetics of the double-base (DB) rocket propellant composed of the mixed ester of triethyleneglycol dinitrate (TEGDN) and nitroglycerin (NG), and nitrocellulose (NC) with lanthanum citrate as a combustion catalyst was investigated by thermogravimetry and differential thermogravimetry (TG-DTG), and differential scanning calorimetry (DSC) under atmospheric pressure and flowing nitrogen gas conditions. The results showed that the thermal decomposition processes of DB propellant had two mass loss stages: volatilization and decomposition of the mixed ester in the first-stage and exothermic decomposition reaction in the second-stage. The exothermic decomposition reaction mechanism obeyed the third-order chemical reaction rule. The kinetic parameters of the reaction were: E a=231.14 kJ·mol –1, A=10 23.29 s –1. The kinetic equation can be expressed as: d α/d t=10 22.99(1– α) 3e –2.78×10 4/ T . The critical temperatures of the thermal explosion of the DB propellant obtained from the onset temperature ( T e) and the peak temperature ( T p) were: T be=463.62 K, T bp=477.88 K. The entropy of activation (Δ S ≠), enthalpy of activation (Δ H ≠), and free energy of activation (Δ G ≠) of the reaction were 219.75 J·mol –1·K –1, 239.23 kJ·mol –1, and 135.96 kJ·mol –1, respectively.

Artificial neural network for modelling thermal decompositions

This paper introduces a new approach based on artificial neural network (ANN) to study the kinetics of thermal decomposition reactions of different polymeric materials, using dynamic thermogravimetry analysis (TGA) at several heating rates. A multilayer neural network model was trained and tested using published experimental data, allowing the proposed model a very good correlation of the weight-loss data. As an example, the same kinetic model has been applied to simultaneously fit runs performed at different heating rates, with different polymeric materials such as polyethylene, cellulose and lignin.