scholarly journals A Kinetic Analysis of the Thermal Degradation Behaviours of Some Bio-Based Substrates

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1830
Author(s):  
Ananya Thomas ◽  
Khalid Moinuddin ◽  
Svetlana Tretsiakova-McNally ◽  
Paul Joseph
Keyword(s):  
Thermal Degradation ◽  
Potato Starch ◽  
Heating Regime ◽  
Heating Rates ◽  
Model Free ◽  
Present Context ◽  
Fwo Method ◽  
Combustion Flow ◽  
The One ◽  
Tamarind Kernel

In the present paper, we report on a detailed study regarding the thermal degradation behaviours of some bio-sourced substrates. These were previously identified as the base materials in the formulations for fireproofing wood plaques through our investigations. The substrates included: β-cyclodextrin, dextran, potato starch, agar-agar, tamarind kernel powder and chitosan. For deducing the Arrhenius parameters from thermograms obtained through routine thermogravimetric analyses (TGA), we used the standard Flynn–Wall–Ozawa (FWO) method and employed an in-house developed proprietary software. In the former case, five different heating rates were used, whereas in the latter case, the data from one dynamic heating regime were utilized. Given that the FWO method is essentially based on a model-free approach that also makes use of multiple heating rates, it can be considered in the present context as superior to the one that is dependent on a single heating rate. It is also relevant to note here that the values of energy of activation (Ea) obtained in each case should only be considered as apparent values at best. Furthermore, some useful, but limited, correlations were identified between the Ea values and the relevant parameters obtained earlier by us from pyrolysis combustion flow calorimetry (PCFC).

scholarly journals Kinetic Analysis of the Thermal Degradation of Recycled Acrylonitrile-Butadiene-Styrene by non-Isothermal Thermogravimetry

Polymers ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 281 ◽  
Author(s):  
Rafael Balart ◽  
David Garcia-Sanoguera ◽  
Luis Quiles-Carrillo ◽  
Nestor Montanes ◽  
Sergio Torres-Giner
Keyword(s):  
Thermal Degradation ◽  
Kinetic Analysis ◽  
Acrylonitrile Butadiene Styrene ◽  
Isoconversional Methods ◽  
Reaction Model ◽  
Integral Model ◽  
Heating Rates ◽  
Exponential Factor ◽  
Model Free ◽  
Butadiene Styrene

This work presents an in-depth kinetic study of the thermal degradation of recycled acrylonitrile-butadiene-styrene (ABS) polymer. Non-isothermal thermogravimetric analysis (TGA) data in nitrogen atmosphere at different heating rates comprised between 2 and 30 K min−1 were used to obtain the apparent activation energy (Ea) of the thermal degradation process of ABS by isoconversional (differential and integral) model-free methods. Among others, the differential Friedman method was used. Regarding integral methods, several methods with different approximations of the temperature integral were used, which gave different accuracies in Ea. In particular, the Flynn-Wall-Ozawa (FWO), the Kissinger-Akahira-Sunose (KAS), and the Starink methods were used. The results obtained by these methods were compared to the Kissinger method based on peak temperature (Tm) measurements at the maximum degradation rate. Combined Kinetic Analysis (CKA) was also carried out by using a modified expression derived from the general Sestak-Berggren equation with excellent results compared with the previous methods. Isoconversional methods revealed negligible variation of Ea with the conversion. Furthermore, the reaction model was assessed by calculating the characteristic and functions and comparing them with some master plots, resulting in a nth order reaction model with n = 1.4950, which allowed calculating the pre-exponential factor (A) of the Arrhenius constant. The results showed that Ea of the thermal degradation of ABS was 163.3 kJ mol−1, while ln A was 27.5410 (A in min−1). The predicted values obtained by integration of the general kinetic expression with the calculated kinetic triplet were in full agreement with the experimental data, thus giving evidence of the accuracy of the obtained kinetic parameters.

scholarly journals Thermal Behavior of Sweet Potato Starch by Non-Isothermal Thermogravimetric Analysis

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 699 ◽  
Author(s):  
Ying Liu ◽  
Liutao Yang ◽  
Chunping Ma ◽  
Yingzhe Zhang
Keyword(s):  
Thermogravimetric Analysis ◽  
Thermal Degradation ◽  
Sweet Potato ◽  
Degradation Kinetics ◽  
Potato Starch ◽  
Activation Energies ◽  
Thermal Degradation Kinetics ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Sweet Potato Starch

In this study, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) methods were used to study the structure, the thermal degradation kinetics, and the thermogram of sweet potato starch, respectively. The thermal decomposition kinetics of sweet potato starch was examined within different heating rates in a nitrogen atmosphere. Different models of kinetic analysis were used to calculate the activation energies using the thermogravimetric data of the thermal degradation process. The activation energies got from Kissinger, Flynn–Wall–Ozawa, and Šatava–Šesták models were 173.85, 174.87, and 174.34 kJ·mol−1, respectively. Thermogravimetry–Fourier transform infrared spectroscopy (TG-FTIR) analysis showed that the main pyrolysis products included water, carbon dioxide, and methane.

scholarly journals Kinetic Analysis of Pyrolysis and Thermo-Oxidative Decomposition of Tennis String Nylon Wastes

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7564
Author(s):  
Haibo Wan ◽  
Zhen Huang
Keyword(s):  
Thermal Degradation ◽  
Kinetic Analysis ◽  
Model Fitting ◽  
Degradation Process ◽  
Nylon 6 ◽  
Reaction Model ◽  
Heating Rates ◽  
Model Free ◽  
Order Chemical Reaction ◽  
First Order Chemical Reaction

Thermal degradation of nylon-6 tennis string nylon wastes in inert nitrogen and air atmospheres was investigated by means of multiple heating-rate thermogravimetric analyses. The results obtained under the heating rates of 5–20 K/min are compared in terms of degradation feature and specific temperature for two atmospheres. Using nonisothermal data, kinetic analysis was thoroughly conducted using various isoconversional model-free methods, including Starink, Madhusudanan–Krishnan–Ninan, Tang, Coats–Redfern, and Flynn–Wall–Ozawa methods. With these kinetic analysis methods, the activation energy over the entire degradation process was successfully calculated. By means of the model-fitting master-plots method, the first-order chemical reaction model was determined to be the most appropriate mechanism function for describing pyrolysis and oxidative thermal degradation of nylon-6 waste. Using kinetic parameters, satisfactory matching against experimental data resulted using the Coats–Redfern method for both cases. Furthermore, thermodynamic parameters such as changes in entropy, enthalpy, and Gibbs free energy during thermal degradation processes were evaluated.

scholarly journals Study of thermal degradation behavior and kinetics of ABS/PC blend

2020 ◽  
Vol 22 (3) ◽  
pp. 64-69
Author(s):  
Saira Bano ◽  
Naveed Ramzan ◽  
Tanveer Iqbal ◽  
Hamayoun Mahmood ◽  
Farhan Saeed
Keyword(s):  
Thermal Degradation ◽  
Mass Loss ◽  
Acrylonitrile Butadiene Styrene ◽  
Entropy Change ◽  
Heating Rates ◽  
Exponential Factor ◽  
Model Free ◽  
Thermogravimetric Curve ◽  
Thermal Degradation Behavior ◽  
Kinetics Of

AbstractThis work investigated kinetics and thermal degradation of acrylonitrile butadiene styrene and polycarbonate (ABS/PC) blend using thermogravimetric analysis in the range of 25 to 520°C. For thermal degradation of blend, activation energy (Ea) and pre-exponential factor (A) were calculated under various heating rates as 5, 10, 15 and 20°C/min using iso-conversional model-free methods (Kissinger, Flynn-Wall- Ozawa and Friedman). Mass loss of the blend as a function of temperature was plotted as thermogravimetric curve (TG) while derivative values of mass loss were drawn as derivative thermogravimetric (DTG) curve. Using Kissinger method, Ea was 51.4 kJ/mol, while values calculated from FWO and Friedman method were 86–161 and 30–251 kJ/mol respectively. Results showed increasing trend of Ea with higher conversion values indicating different degradation mechanisms at the initial and final stages of the experiment. Thermodynamic parameters such as enthalpy change (ΔH), Gibbs free energy (ΔG) and entropy change (ΔS) were also calculated.

Thermal degradation kinetics and lifetime of HDPE/PLLA/pro-oxidant blends

2016 ◽  
Vol 36 (9) ◽  
pp. 917-931 ◽  
Author(s):  
Gaurav Madhu ◽  
Dev K. Mandal ◽  
Haripada Bhunia ◽  
Pramod K. Bajpai
Keyword(s):  
Activation Energy ◽  
Thermal Degradation ◽  
Degradation Kinetics ◽  
Model Fitting ◽  
Frequency Factor ◽  
Thermal Degradation Kinetics ◽  
Heating Rates ◽  
Model Free ◽  
Calculation Technique ◽  
Thermal Degradation Behavior

Abstract The effect of adding poly(L-lactic acid) (PLLA) with and without a pro-oxidant additive cobalt stearate (CoSt) and compatibilizer maleic anhydride grafted polyethylene (MA-g-PE) on the thermal degradation and stability of high-density polyethylene (HDPE) films was analyzed using thermogravimetric analysis (TGA). The kinetic parameters [i.e. activation energy (Ea), order of reaction (n), and frequency factor ln(A)] of the samples were studied over a temperature range of 25°C–600°C at four heating rates (i.e. 5, 10, 15, and 20°C/min) through model-free techniques (e.g. Friedman, second Kissinger, and Flynn-Wall-Ozawa) and model-fitting techniques (e.g. Freeman-Carroll and Kim-Park). The value of Ea for neat HDPE was found to be much higher than PLLA; for the HDPE/PLLA blend, it was nearer to that of HDPE. An increase in the activation energy of 80/20 (HDPE/PLLA) blend was noticed by the addition of MA-g-PE. The TGA data and degradation kinetics were also used to predict the lifetime of the film samples. The lifetime of HDPE was found to decrease with the increase in the concentration of CoSt, thereby revealing its pro-oxidative ability. Minimum lifetime was noted for the HDPE/PLLA (80/20) sample blended with CoSt, which increased slightly in the presence of MA-g-PE. Studies indicated that the thermal degradation behavior and lifetime of the investigated film samples depends not only on the fractions of their constituents but also on the heating rates and calculation technique.

scholarly journals Eriobotrya japonica Lindl. Kernels: Kinetics of Thermal Degradation under Inert Atmosphere Using Model-Free and Fitting Methods

2020 ◽  
Vol 11 (4) ◽  
pp. 11357-11379
Keyword(s):  
Activation Energy ◽  
Thermal Degradation ◽  
Mass Loss ◽  
Kinetic Parameters ◽  
Inert Atmosphere ◽  
Eriobotrya Japonica ◽  
Heating Rates ◽  
Noticeable Effect ◽  
Exponential Factor ◽  
Model Free

A kinetic study of the pyrolysis process of raw Eriobotrya japonica Lindl. Kernels (RLK) was investigated using a thermogravimetric analyzer. The weight loss was measured in a nitrogen atmosphere. The samples were heated over a range of temperature from 298 K to 873 K with four different heating rates of 5, 10, 15, 20 K min-1. Mass loss (TGA) and derivative mass loss (DTG) measurements indicate that the increase in heating rate has no noticeable effect on the thermal degradation of the RLK. The results obtained from the thermal decomposition process indicate that there are three main stages such as dehydration, active, and passive pyrolysis. TGA curves indicate that active pyrolysis of RLK is between 160 and 450 °C. In this interval, a shoulder followed by a peak exists on the DTG plots. The shoulder corresponds to the decomposition of hemicelluloses, the first peak to that of cellulose. Lignin decomposes through all temperature range. The kinetic parameters such as activation energy and pre-exponential factor were obtained for two degradation steps by isoconversional model-free methods proposed by FWO, KAS, Kissinger, Tang, MKN, and FR, with degradation mode being: f(α)=(1-α)n with n = 1 for FR and g(α)=-Ln(1- α) for the other methods. The activation energy and pre-exponential factor obtained by the Kissinger method are 173 kJ/mol and 1.9×1016 min-1. While for free model methods, the average kinetic parameters calculated are 172-248 kJ.mol-1 and 5,30×1020 for integral methods (FWO, KAS, Tang and MKN) and 190-271 kJ.mol-1 and 1.77×1022 min-1 for differential Fr method. The activation energy decreases in the final stages of the process. The energy required for hemicellulose degradation is lower than that of cellulose. The most probable reaction functions have thus been determined for these two stages by Coats-Redfern and Criado method, leading to greatly improved calculation performance over the entire conversion range. The reaction, second-order F2, describes the pyrolysis reaction models of RLK. With the Arrhenius parameters obtained from the fitting model of CR, we attempt to reconstruct the temperature-dependent mass conversion curves and have resulted in generally acceptable results. Based on the Arrhenius parameter values obtained by Kissinger equation, the changes in entropy, enthalpy and Gibbs free energy, and lifetime predictions have been estimated concerning the thermal degradation processes of RLK.

Thermal degradation kinetics and lifetime of high-density polyethylene/poly (l-lactic acid) blends

2015 ◽  
Vol 30 (6) ◽  
pp. 773-793 ◽  
Author(s):  
Gaurav Madhu ◽  
Dev K Mandal ◽  
Haripada Bhunia ◽  
Pramod K Bajpai
Keyword(s):  
Lactic Acid ◽  
Thermal Degradation ◽  
High Density Polyethylene ◽  
Degradation Kinetics ◽  
Estimation Method ◽  
Frequency Factor ◽  
High Density ◽  
Thermal Degradation Kinetics ◽  
Heating Rates ◽  
Model Free

In this work, a kinetic study on the thermal degradation of films prepared from high-density polyethylene (HDPE), poly(l-lactic acid) (PLLA) and their blends is presented. Activation energy ( Ea), order of reaction ( n) and frequency factor (ln ( A)) were studied through thermogravimetric analysis (TGA) over a temperature range of 25–600°C at four heating rates, that is, 5, 10, 15, and 20°C min−1. The TGA data were used to predict the thermal stability of the film samples, comparing the kinetic parameters obtained by three model-free isoconversional techniques and estimating the lifetime of the films. The value of Ea for neat HDPE was found to be much higher than that for PLLA, but for HDPE/PLLA blends, it was nearer to that of HDPE. An increase in Ea of 80/20 (HDPE/PLLA) blends was noticed with the addition of compatibilizer, maleic anhydride-grafted HDPE. Overall, the thermal kinetics of the polymer samples depends on fractions of their constituents, heating rates and calculation technique used. It was proved, through lifetime estimation method, that the lifetime of neat HDPE decreases by addition of PLLA. With increase in temperature, the lifetime of all samples decreased exponentially. Scanning electron microscopy studies verified that HDPE and PLLA interfaces became fairly compatible by adding the compatibilizer.

Thermal degradation kinetics of Opuntia Ficus Indica flour and talc-filled poly (lactic acid) hybrid biocomposites by TGA analysis

2021 ◽  
pp. 002199832110082
Author(s):  
Azzeddine Gharsallah ◽  
Abdelheq Layachi ◽  
Ali Louaer ◽  
Hamid Satha
Keyword(s):  
Thermal Stability ◽  
Lactic Acid ◽  
Thermal Degradation ◽  
Degradation Kinetics ◽  
Degradation Mechanism ◽  
Melt Processing ◽  
Thermal Degradation Kinetics ◽  
Poly Lactic Acid ◽  
Opuntia Ficus Indica ◽  
Model Free

This paper reports the effect of lignocellulosic flour and talc powder on the thermal degradation behavior of poly (lactic acid) (PLA) by thermogravimetric analysis (TGA). Lignocellulosic flour was obtained by grinding Opuntia Ficus Indica cladodes. PLA/talc/ Opuntia Ficus Indica flour (OFI-F) biocomposites were prepared by melt processing and characterized using Wide-angle X-ray scattering (WAXS) and Scanning Electron Microscope (SEM). The thermal degradation of neat PLA and its biocomposites can be identified quantitatively by solid-state kinetics models. Thermal degradation results on biocomposites compared to neat PLA show that talc particles at 10 wt % into the PLA matrix have a minor impact on the thermal stability of biocomposites. Loading OFI-F and Talc/OFI-F mixture into the PLA matrix results in a decrease in the maximum degradation temperature, which means that the biocomposites have lower thermal stability. The activation energies (Ea) calculated by the Flynn Wall Ozawa (FWO) and Kissinger Akahira Sunose (KAS) model-free approaches and by model-fitting (Kissinger method and Coats-Redfern method) are in good agreement with one another. In addition, in this work, the degradation mechanism of biocomposites is proposed using Coats-Redfern and Criado methods.

Thermo-catalytic decomposition of polystyrene waste: Comparative analysis using different kinetic models

2019 ◽  
Vol 38 (2) ◽  
pp. 202-212 ◽  
Author(s):  
Ghulam Ali ◽  
Jan Nisar ◽  
Munawar Iqbal ◽  
Afzal Shah ◽  
Mazhar Abbas ◽  
...  
Keyword(s):  
Activation Energy ◽  
Copper Oxide ◽  
Solid Waste ◽  
Thermodynamic Parameters ◽  
Model Fitting ◽  
Catalytic Decomposition ◽  
Decomposition Reaction ◽  
Inert Atmosphere ◽  
Heating Rates ◽  
Model Free

Due to a huge increase in polymer production, a tremendous increase in municipal solid waste is observed. Every year the existing landfills for disposal of waste polymers decrease and the effective recycling techniques for waste polymers are getting more and more important. In this work pyrolysis of waste polystyrene was performed in the presence of a laboratory synthesized copper oxide. The samples were pyrolyzed at different heating rates that is, 5°Cmin−1, 10°Cmin−1, 15°Cmin−1 and 20°Cmin−1 in a thermogravimetric analyzer in inert atmosphere using nitrogen. Thermogravimetric data were interpreted using various model fitting (Coats–Redfern) and model free methods (Ozawa–Flynn–Wall, Kissinger–Akahira–Sunose and Friedman). Thermodynamic parameters for the reaction were also determined. The activation energy calculated applying Coats–Redfern, Ozawa–Flynn–Wall, Kissinger–Akahira–Sunose and Friedman models were found in the ranges 105–148.48 kJmol−1, 99.41–140.52 kJmol−1, 103.67–149.15 kJmol−1 and 99.93–141.25 kJmol−1, respectively. The lowest activation energy for polystyrene degradation in the presence of copper oxide indicates the suitability of catalyst for the decomposition reaction to take place at lower temperature. Moreover, the obtained kinetics and thermodynamic parameters would be very helpful in determining the reaction mechanism of the solid waste in a real system.

Global Reaction Model to Describe the Kinetics of Catalytic Pyrolysis of Coffee Grounds Waste

2017 ◽  
Vol 899 ◽  
pp. 173-178 ◽  
Author(s):  
Ronydes Batista Jr. ◽  
Bruna Sene Alves Araújo ◽  
Pedro Ivo Brandão e Melo Franco ◽  
Beatriz Cristina Silvério ◽  
Sandra Cristina Danta ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Large Scale ◽  
Catalytic Pyrolysis ◽  
Petroleum Products ◽  
Reaction Model ◽  
Heating Rates ◽  
Coffee Grounds ◽  
One Step ◽  
Global Reaction ◽  
The One

In view of the constant search for new sources of renewable energy, the particulate agro-industrial waste reuse emerges as an advantageous alternative. However, despite the advantages of using the biomass as an energy source, there is still strong resistance as the large-scale replacement of petroleum products due to the lack of scientifically proven efficient conversion technologies. In this context, the pyrolysis is presented as one of the most widely used thermal decomposition processes. The knowledge of aspects of chemical kinetics, thermodynamics these will, heat and mass transfer, are so important, since influence the quality of the product. This paper presents a kinetic study of slow pyrolysis of coffee grounds waste from dynamic thermogravimetric experiments (TG), using different powder catalysts. The primary thermal decomposition was described by the one-step reaction model, which considers a single global reaction. The kinetic parameters were estimated using nonlinear regression and the differential evolution method. The coffee ground waste was dried at 105°C for 24 hours. The sample in nature was analyzed at different heating rates, being 10, 15, 20, 30 and 50 K/min. In the catalytic pyrolysis, about 5% (w/w) of catalyst were added to the sample, at a heating rate of 30 K/min. The results show that the one-step model does not accurately represent the data of weight loss (TG) and its derivative (DTG), but can do an estimative of the activation energy reaction, and can show the differences caused by the catalysts. Although no one can say anything about the products formed with the addition of the catalyst, it would be necessary to micro-pyrolysis analysis, we can say the influence of the catalyst in the samples, based on the data obtained in thermogravimetric tests.

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