Article
Engineering, Environmental
Kesiany M. de Souza, Marcelo J. S. de Lemos, Roberta dos R. Ribeiro, Ana Maria G. Marin
Summary: The transition to a carbon-free economy has led to the development of innovative technologies for permanent P&A of mature oil wells, such as the use of thermites in Thermal P&A technology. This study presents a comprehensive kinetic analysis of the Fe2O3-2Al thermite reaction using DSC data. Multiple kinetic methods were employed to calculate the activation energies for each reaction stage, revealing significant variations with the extent of conversion. Different models were used to describe the reaction stages, with the first stage following a contracting sphere mechanism and the second stage following a random nucleation mechanism. The modeled data showed good agreement with the experimental data for the first stage, but larger deviations were observed for the second stage.
CHEMICAL ENGINEERING JOURNAL
(2023)
Article
Thermodynamics
Laipeng Luo, Zhiyi Zhang, Chong Li, Nishu, Fang He, Xingguang Zhang, Junmeng Cai
Summary: In analyzing kinetic reactions of solid-state reactions like lignocellulosic biomass pyrolysis, the accuracy of determining the kinetic mechanism function using the master plots method depends strongly on the variation degree of the frequency factor with conversion and the conversion dependency of activation energy. Failure to consider these factors when utilizing the master plots method may lead to misestimating the kinetic mechanism function.
Article
Polymer Science
Nathanael Guigo, George Z. Papageorgiou, Nikki Poulopoulou, Dimitrios N. Bikiaris, Nicolas Sbirrazzuoli
Summary: Biobased poly(hexamethylene 2,5-furan dicarboxylate) (PHF) was successfully synthesized by a two-stage melt polycondensation method. The nonisothermal crystallization from the melt and glass states was studied using various thermal analysis techniques. The research reveals the changes in the crystallization mechanism and proposes a method for accurately simulating the crystallization rate curve.
Article
Polymer Science
Nasrollah Hamidi
Summary: PVC tubing products have replaced cast iron sewer and piping systems, metal and wood in window frames. The availability of disposed or postconsumer PVC allows for upcycling, recycling, and downcycling, creating economic opportunities and reducing environmental burden. This study examines the thermal characteristics of a film made of wPVC and evaluates the isoconversional degradation energy barrier values using kinetic models.
JOURNAL OF APPLIED POLYMER SCIENCE
(2023)
Article
Polymer Science
Ahmad A. Joraid, Rawda M. Okasha, Mahdi A. Al-Maghrabi, Tarek H. Afifi, Christian Agatemor, Alaa S. Abd-El-Aziz
Summary: The objective of this study is to determine the thermodynamic parameters of two degradation steps observed in three novel families of organometallic dendrimers. The results show consistent tendencies between changes in enthalpy, entropy, and activation energy, while the change in Gibbs free energy remains positive throughout the degradation process, indicating that degradation is non-spontaneous.
JOURNAL OF INORGANIC AND ORGANOMETALLIC POLYMERS AND MATERIALS
(2022)
Article
Chemistry, Analytical
Chong Li, Hanqi Duan, Xiaojuan Guo, Junmeng Cai
Summary: This paper discusses the use of exponential temperature change in nonisothermal kinetics of thermally stimulated processes, and proposes two more accurate approximations for temperature integrals. These new approximations are shown to be more accurate in evaluating the integrals compared to traditional methods.
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
(2021)
Article
Thermodynamics
Lerys Granado, Nicolas Sbirrazzuoli
Summary: Isoconversional analysis is a model-free and powerful approach that provides quantitative information of the kinetics, with main outputs of activation energy and preexponential factor. It allows for accurate predictions of nonisothermal kinetics profiles, showing excellent agreements with simulated curves, even for multistep kinetic programs. The dependence of heating rates on the shift of nonisothermal kinetics profiles is briefly discussed by the authors.
THERMOCHIMICA ACTA
(2021)
Article
Thermodynamics
Nicolas Sbirrazzuoli
Summary: Four complex mechanisms of two parallel independent reactions were simulated under various isothermal and nonisothermal conditions based on the isoconversional methods of Vyazovkin and Friedman. The study showed that accurate simulations can be performed in a model-free way, with higher accuracy obtained for mechanisms involving more separated individual steps. The proposed methods are applicable to both DSC and TG data.
THERMOCHIMICA ACTA
(2021)
Article
Polymer Science
Sergey Vyazovkin
Summary: The Jeziorny method replaces temperature values with corresponding time values in the isothermal Avrami plot to analyze nonisothermal crystallization data. However, this method is not applicable for nonisothermal data, as the intercept and slope of the plot cannot be interpreted as rate constant and Avrami exponent, respectively.
Article
Thermodynamics
Nicolas Sbirrazzuoli
Summary: This study simulated three different complex multi-step reaction mechanisms, including parallel-competing, consecutive, and parallel-independent reactions, using two sets of different kinetic parameters. The analysis of thermoanalytical curves and E alpha-dependencies, combined with model-fitting approach, can elucidate reaction mechanisms and estimate kinetic parameters for each step.
THERMOCHIMICA ACTA
(2023)
Article
Green & Sustainable Science & Technology
Pollyana R. Carvalho, Samuel L. S. Medeiros, Raul L. Paixao, Igor M. Figueredo, Adriano L. A. Mattos, M. Alexsandra S. Rios
Summary: Thermogravimetric pyrolysis of carnauba straw and carnauba stalk was studied and the kinetic parameters, FTIR spectra, and molar ratios were obtained, which were in good agreement with other reported biomasses.
Article
Chemistry, Multidisciplinary
Zhongsuo Liu
Summary: Metallurgical coke gasification by carbon dioxide was kinetically investigated using thermogravimetric analysis under nonisothermal conditions. The activation energy was estimated using the Cai-Chen iterative model-free method, and the most probable mechanism function was determined to be the Johnson-Mehl-Avrami equation based on the Malek master-plot method. The compound kinetic calculation technique combining the Malek master-plot and Cai-Chen model-free methods was verified for estimating reaction kinetics of metallurgical coke gasification.
Article
Chemistry, Applied
Yunhao Liang, Michael E. Ries, Peter J. Hine
Summary: The pyrolysis kinetics of cellulosic fibres, specifically a natural cotton yarn (NCY) and a mercerized cotton yarn (MCY), were investigated using a modified first order global analysis method (FOG) and thermogravimetric analysis (TGA). The results showed that the intrinsic pyrolysis activation energy of NCY and MCY was independent of heating rate and approximation used, with average values of 153 +/- 2 kJ/mol and 192 +/- 7 kJ/mol, respectively. The difference in chemical composition and crystalline structure were hypothesized to be the reasons for the different values. This study provides a new approach for studying the pyrolysis kinetics of biomass and factors influencing their pyrolytic behavior.
CARBOHYDRATE POLYMERS
(2023)
Article
Materials Science, Ceramics
Suman Pawaria, Jyoti Ahlawat, Preeti Sharma, Sajjan Dahiya, Anil Ohlan, R. Punia, A. S. Maan
Summary: The glass transition and crystallization kinetics of lithium-modified zinc borate glasses with different compositions were studied using differential scanning calorimetry. The glass composition of 20ZnO·10Li2O·70B2O3 showed the highest thermal stability and glass-forming tendency among all other compositions. The activation energies for crystallization and glass transition were determined and found to be in close agreement with each other. The formation of a pure monoclinic LiZnBO3 crystalline phase was observed in certain compositions, which has potential for electric double-layer capacitance fabrication.
CERAMICS INTERNATIONAL
(2023)
Article
Materials Science, Multidisciplinary
Muhammad Helmi Abdul Kudus, Muhammad Razlan Zakaria, Mohd Firdaus Omar, Muhammad Bisyrul Hafi Othman, Hazizan Md Akil, Marcin Nabialek, Bartlomiej Jez, Mohd Mustafa Al Bakri Abdullah
Summary: The study explores the thermal degradation kinetics and lifetime prediction of epoxy composites with different loadings of CNT/alumina, demonstrating the significant contribution of CNT/alumina hybrid filler to the thermal properties of the composites. The higher Ea associated with increased CNT/alumina hybrid loading indicates improved thermal degradation and stability of the materials.
Article
Chemistry, Multidisciplinary
Michal Novotny, Matus Dubecky, Frantisek Karlicky
Summary: This paper investigates the accuracy of different DFT-based computational approaches in calculating the equilibrium lattice constants and exfoliation energy of hexagonal boron nitride (h-BN). The results are compared with experiments and reference QMC calculations to evaluate the accuracy of these computational methods.
JOURNAL OF COMPUTATIONAL CHEMISTRY
(2024)
Article
Chemistry, Multidisciplinary
Luigi Crisci, Federico Coppola, Alessio Petrone, Nadia Rega
Summary: The charge transfer dynamics in asymmetrically substituted indenotetracene molecules upon photo-excitation were investigated using real-time time-dependent density functional theory simulations. The study found that the electron-donating character of the substituents affects the overall electronic energy spacing and ultrafast charge transfer dynamics.
JOURNAL OF COMPUTATIONAL CHEMISTRY
(2024)
Article
Chemistry, Multidisciplinary
Vasilii Korotenko, Hendrik Zipse
Summary: The stability of various radicals and molecules has been studied using different theoretical methods, and good correlations between theoretical calculations and experimental results have been found. The effects of hydrogen bonding interactions on the stability of oxygen-centered radicals have also been investigated.
JOURNAL OF COMPUTATIONAL CHEMISTRY
(2024)
Article
Chemistry, Multidisciplinary
Oleg Egorov, Michael Rey, Dominika Viglaska, Andrei V. Nikitin
Summary: In this work, the rovibrational energy levels of four isotopologues of methylene were calculated using a new accurate ab initio potential energy surface. The accuracy of the calculations was improved by considering scalar relativistic effects, DBOC, and high-order electronic correlations. For the first time, all available experimental rovibrational transitions were reproduced with high accuracy, without any empirical corrections.
JOURNAL OF COMPUTATIONAL CHEMISTRY
(2024)