E-Mail Alert

Add your e-mail address to receive forthcoming issues of this journal:

Journal Browser

Journal Browser

Special Issue "Thermal Analysis Kinetics for Understanding Materials Behavior"

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Physical Chemistry".

Deadline for manuscript submissions: 30 June 2019

Special Issue Editor

Guest Editor
Prof. Dr. Sergey Vyazovkin

Department of Chemistry, University of Alabama at Birmingham, Birmingham, Alabama, USA
Website | E-Mail
Interests: kinetics and mechanisms of thermally stimulated processes; chemical reactions in the condensed phase; phase transitions; polymeric, pharmaceutical, and energetic materials

Special Issue Information

Dear Colleagues,

Changing the temperature of a substance can stimulate dramatic changes of its state. These changes can be intermolecular (physical) and intramolecular (chemical) in nature. Physical changes occur without breaking intramolecular bonds, and lead to transitions between the four major phases: gas, liquid, crystal, and glass. Chemical changes are associated with chemical reactions that originate from breaking intramolecular bonds. Phase transitions as well as chemical reactions occur at finite rates. Measuring the rates of processes is the realm of kinetics. The kinetics of thermally stimulated processes is measured routinely by thermal analysis techniques such as differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).

Knowing the process rates and their dependence on temperature is of vital importance for understanding the behavior of materials exposed to variations in temperature. For example, the successful function of glassy materials is contingent upon negligibly small rates of the transition from the glass to crystalline phase. On the other hand, phase change materials rely on rapid transition between the liquid and crystalline phases. Similar principles hold for chemical reactions. Slower rates of chemical decomposition give rise to longer drug shelf lives. However, very fast decomposition rates determine the efficiency of explosives and propellants.

In recent years, thermal analysis kinetics has made significant progress by developing computational tools for reliable kinetic analysis. It has also expanded its traditional application area to newly developed nano- and bio-materials. The purpose of this Special Issue is to collect a series of papers that reflect recent developments in the field and highlight the essential role of thermal analysis kinetics in understanding the processes responsible for the thermal behavior of various materials. The processes of interest involve (but are not limited to): thermal decomposition (degradation), polymerization, crosslinking (curing), oxidation, reduction, crystallization, melting, and glass and solid–solid transitions.

Prof. Dr. Sergey Vyazovkin
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • nonisothermal and isothermal kinetics
  • Arrhenius parameters
  • activation energy, preexponential factor, reaction model
  • differential scanning calorimetry (DSC)
  • thermogravimetric analysis (TGA)
  • thermal decomposition
  • thermal and thermo-oxidative degradation
  • polymerization
  • crosslinking (curing)
  • oxidation and reduction
  • crystallization
  • melting
  • glass transition
  • solid–solid (morphological) transition

Published Papers (6 papers)

View options order results:
result details:
Displaying articles 1-6
Export citation of selected articles as:

Research

Jump to: Review

Open AccessArticle
Investigation of Size-Dependent Sublimation Kinetics of 2,4,6-Trinitrotoluene (TNT) Micro-Islands Using In Situ Atomic Force Microscopy
Molecules 2019, 24(10), 1895; https://doi.org/10.3390/molecules24101895
Received: 18 April 2019 / Revised: 10 May 2019 / Accepted: 14 May 2019 / Published: 17 May 2019
PDF Full-text (1937 KB) | HTML Full-text | XML Full-text
Abstract
Kinetic thermal analysis was conducted using in situ atomic force microscopy (AFM) at a temperature range of 15–25 °C to calculate the activation energy of the sublimation of 2,4,6-trinitrotoluene (TNT) islands. The decay of different diameter ranges (600–1600 nm) of TNT islands was [...] Read more.
Kinetic thermal analysis was conducted using in situ atomic force microscopy (AFM) at a temperature range of 15–25 °C to calculate the activation energy of the sublimation of 2,4,6-trinitrotoluene (TNT) islands. The decay of different diameter ranges (600–1600 nm) of TNT islands was imaged at various temperatures isothermally such that an activation energy could be obtained. The activation energy of the sublimation of TNT increases as the diameter of islands increases. It was found that the coarsening and the sublimation rate of TNT islands can be determined by the local environment of the TNT surface. This result demonstrates that a diffusion model cannot be simply applied to “real world” systems for explaining the sublimation behavior and for estimating the coarsening of TNT. Full article
(This article belongs to the Special Issue Thermal Analysis Kinetics for Understanding Materials Behavior)
Figures

Figure 1

Open AccessArticle
Thermal Decomposition Kinetics and Mechanism of In-Situ Prepared Bio-Based Poly(propylene 2,5-furan dicarboxylate)/Graphene Nanocomposites
Molecules 2019, 24(9), 1717; https://doi.org/10.3390/molecules24091717
Received: 4 April 2019 / Revised: 27 April 2019 / Accepted: 1 May 2019 / Published: 2 May 2019
PDF Full-text (5594 KB) | HTML Full-text | XML Full-text
Abstract
Bio-based polyesters are a new class of materials that are expected to replace their fossil-based homologues in the near future. In this work, poly(propylene 2,5-furandicarboxylate) (PPF) nanocomposites with graphene nanoplatelets were prepared via the in-situ melt polycondensation method. The chemical structure of the [...] Read more.
Bio-based polyesters are a new class of materials that are expected to replace their fossil-based homologues in the near future. In this work, poly(propylene 2,5-furandicarboxylate) (PPF) nanocomposites with graphene nanoplatelets were prepared via the in-situ melt polycondensation method. The chemical structure of the resulting polymers was confirmed by 1H-NMR spectroscopy. Thermal stability, decomposition kinetics and the decomposition mechanism of the PPF nanocomposites were studied in detail. According to thermogravimetric analysis results, graphene nanoplatelets did nοt affect the thermal stability of PPF at levels of 0.5, 1.0 and 2.5 wt.%, but caused a slight increase in the activation energy values. Pyrolysis combined with gas chromatography and mass spectroscopy revealed that the decomposition mechanism of the polymer was not altered by the presence of graphene nanoplatelets but the extent of secondary homolytic degradation reactions was increased. Full article
(This article belongs to the Special Issue Thermal Analysis Kinetics for Understanding Materials Behavior)
Figures

Figure 1

Open AccessArticle
Advanced Isoconversional Kinetic Analysis for the Elucidation of Complex Reaction Mechanisms: A New Method for the Identification of Rate-Limiting Steps
Molecules 2019, 24(9), 1683; https://doi.org/10.3390/molecules24091683
Received: 9 April 2019 / Revised: 24 April 2019 / Accepted: 25 April 2019 / Published: 30 April 2019
PDF Full-text (3136 KB) | HTML Full-text | XML Full-text
Abstract
Two complex cure mechanisms were simulated. Isoconversional kinetic analysis was applied to the resulting data. The study highlighted correlations between the reaction rate, activation energy dependency, rate constants for the chemically controlled part of the reaction and the diffusion-controlled part, activation energy and [...] Read more.
Two complex cure mechanisms were simulated. Isoconversional kinetic analysis was applied to the resulting data. The study highlighted correlations between the reaction rate, activation energy dependency, rate constants for the chemically controlled part of the reaction and the diffusion-controlled part, activation energy and pre-exponential factors of the individual steps and change in rate-limiting steps. It was shown how some parameters computed using Friedman’s method can help to identify change in the rate-limiting steps of the overall polymerization mechanism as measured by thermoanalytical techniques. It was concluded that the assumption of the validity of a single-step equation when restricted to a given α value holds for complex reactions. The method is not limited to chemical reactions, but can be applied to any complex chemical or physical transformation. Full article
(This article belongs to the Special Issue Thermal Analysis Kinetics for Understanding Materials Behavior)
Figures

Graphical abstract

Open AccessArticle
Kinetic Analysis of Digestate Slow Pyrolysis with the Application of the Master-Plots Method and Independent Parallel Reactions Scheme
Molecules 2019, 24(9), 1657; https://doi.org/10.3390/molecules24091657
Received: 7 March 2019 / Revised: 25 April 2019 / Accepted: 25 April 2019 / Published: 27 April 2019
PDF Full-text (2170 KB) | HTML Full-text | XML Full-text
Abstract
The solid fraction obtained by mechanical separation of digestate from anaerobic digestion plants is an attractive feedstock for the pyrolysis process. Especially in the case of digestate obtained from biogas plants fed with energy crops, this can be considered a lignin rich residue. [...] Read more.
The solid fraction obtained by mechanical separation of digestate from anaerobic digestion plants is an attractive feedstock for the pyrolysis process. Especially in the case of digestate obtained from biogas plants fed with energy crops, this can be considered a lignin rich residue. The aim of this study is to investigate the pyrolytic kinetic characteristics of solid digestate. The Starink model-free method has been used for the kinetic analysis of the pyrolysis process. The average Activation Energy value is about 204.1 kJ/mol, with a standard deviation of 25 kJ/mol, which corresponds to the 12% of the average value. The activation energy decreased along with the conversion degree. The variation range of the activation energy is about 99 kJ/mol, this means that the average value cannot be used to statistically represent the whole reaction. The Master-plots method was used for the determination of the kinetic model, obtaining that n-order was the most probable one. On the other hand, the process cannot be modeled with a single-step reaction. For this reason it has been used an independent parallel reactions scheme to model the complete process. Full article
(This article belongs to the Special Issue Thermal Analysis Kinetics for Understanding Materials Behavior)
Figures

Figure 1

Open AccessArticle
Non-Isothermal Sublimation Kinetics of 2,4,6-Trinitrotoluene (TNT) Nanofilms
Molecules 2019, 24(6), 1163; https://doi.org/10.3390/molecules24061163
Received: 27 January 2019 / Revised: 17 March 2019 / Accepted: 20 March 2019 / Published: 23 March 2019
PDF Full-text (2088 KB) | HTML Full-text | XML Full-text
Abstract
Non-isothermal sublimation kinetics of low-volatile materials is more favorable over isothermal data when time is a crucial factor to be considered, especially in the subject of detecting explosives. In this article, we report on the in-situ measurements of the sublimation activation energy for [...] Read more.
Non-isothermal sublimation kinetics of low-volatile materials is more favorable over isothermal data when time is a crucial factor to be considered, especially in the subject of detecting explosives. In this article, we report on the in-situ measurements of the sublimation activation energy for 2,4,6-trinitrotoluene (TNT) continuous nanofilms in air using rising-temperature UV-Vis absorbance spectroscopy at different heating rates. The TNT films were prepared by the spin coating deposition technique. For the first time, the most widely used procedure to determine sublimation rates using thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC) was followed in this work using UV-Vis absorbance spectroscopy. The sublimation kinetics were analyzed using three well-established calculating techniques. The non-isothermal based activation energy values using the Ozawa, Flynn–Wall, and Kissinger models were 105.9 ± 1.4 kJ mol−1, 102.1 ± 2.7 kJ mol−1, and 105.8 ± 1.6 kJ mol−1, respectively. The calculated activation energy agreed well with our previously reported isothermally-measured value for TNT nanofilms using UV-Vis absorbance spectroscopy. The results show that the well-established non-isothermal analytical techniques can be successfully applied at a nanoscale to determine sublimation kinetics using absorbance spectroscopy. Full article
(This article belongs to the Special Issue Thermal Analysis Kinetics for Understanding Materials Behavior)
Figures

Figure 1

Review

Jump to: Research

Open AccessFeature PaperReview
All You Need to Know about the Kinetics of Thermally Stimulated Reactions Occurring on Cooling
Molecules 2019, 24(10), 1918; https://doi.org/10.3390/molecules24101918 (registering DOI)
Received: 1 May 2019 / Revised: 17 May 2019 / Accepted: 17 May 2019 / Published: 18 May 2019
PDF Full-text (2321 KB) | HTML Full-text | XML Full-text
Abstract
In this tutorial overview article the authors share their original experience in studying the kinetics of thermally stimulated reactions under the conditions of continuous cooling. It is stressed that the kinetics measured on heating is similar to that measured on cooling only for [...] Read more.
In this tutorial overview article the authors share their original experience in studying the kinetics of thermally stimulated reactions under the conditions of continuous cooling. It is stressed that the kinetics measured on heating is similar to that measured on cooling only for single-step reactions. For multi-step reactions the respective kinetics can differ dramatically. The application of an isoconversional method to thermogravimetry (TGA) or differential scanning calorimetry (DSC) data allows one to recognize multi-step kinetics in the form of the activation energy that varies with conversion. Authors’ argument is supported by theoretical considerations as well as by experimental examples that include the reactions of thermal decomposition and crosslinking polymerization (curing). The observed differences in the kinetics measured on heating and cooling ultimately manifest themselves in the Arrhenius plots of the opposite curvatures, which means that the heating kinetics cannot be used to predict the kinetics on cooling. The article provides important background knowledge necessary for conducting successful kinetic studies on cooling. It includes a practical advice on optimizing the parameters of cooling experiments as well as on proper usage of kinetic methods for analysis of obtained data. Full article
(This article belongs to the Special Issue Thermal Analysis Kinetics for Understanding Materials Behavior)
Figures

Figure 1

Molecules EISSN 1420-3049 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top