Non-isothermal Thermogravimetric Data Research Articles

Thermal degradation kinetics of recycled biodegradable and non-biodegradable polymer blends either neat or in the presence of nanoparticles using the random chain-scission model

One of the major issues in polymer recycling nowadays is related to the impact of biodegradable polymers and/or nanoparticles’ presence on the thermal degradation kinetics of non-biodegradable polymers used mainly in packaging. In this direction, the thermal degradation kinetics of PET/PLA blends was investigated using non-isothermal thermogravimetric data and a simulation model based on the random-scission mechanism. Specifically, we extended the model originally developed by Sánchez-Jiménez, Pérez-Maqueda and Criado based on the original idea of Simha and Wall to simulate the thermal degradation of polymer blends in pyrolytic conditions. A system of differential equations was set and solved based only on the kinetic parameters obtained from the neat polymers and without any additional adjustable parameter. It was found that this model describes fairly well the thermal degradation of several PET/PLA blends in a large conversion range. Deviations were observed at low conversions where degradation of PLA is promoted by ester interchange reactions with PET and at intermediate conversions where possible synergistic effects may take place. Furthermore, the addition of nanoparticles seem to retard the diffusion of the volatile degradation products out of the polymer, so that the onset of mass loss is at higher temperatures for the blend nanocomposites compared to neat blend. This was taken into account in the model by including an additional diffusion-related term to the kinetic constant of the degradation.

Shedding light on the mechanism of graphene oxide thermal decomposition: A kinetic study using isoconversional method and artificial neural network

This work investigates the kinetics of Graphene Oxide (GO) thermal decomposition in mild temperatures (<550 K) using non-isothermal thermogravimetric data of freeze-dried GO. We employed the isoconvertional method and an artificial neural network to determine the multiple mechanistic kinetic models involved. Two distinct steps were clearly observed, both with high contribution of first-order kinetic model due to the dependence on the concentration of oxygen functionalities. Moreover, the first step of decomposition showed significant contribution of 3D diffusion model, likely related to the diffusion of produced gases in the 3D stacked-layered structure. The second step does not show dependence on 3D diffusion anymore, suggesting the layered structure was exfoliated during the first step. The second step showed high contribution of 2D nucleation models, which imply the formation of holes and cracks in the GO carbon skeleton. Therefore, this work clarifies the mechanism of preparation of reduced GO (rGO).

Potential of macauba endocarp (Acrocomia aculeate) for bioenergy production: Multi-component kinetic study and estimation of thermodynamic parameters of activation

This work provides the first insights on the bioenergy potential of macauba endocarp (Acrocomia aculeate) based on the pyrolysis kinetics and thermodynamic parameters of activation. The kinetic triplet was obtained from non-isothermal thermogravimetric data by using four isoconversional methods, kinetic compensation effect, and master-plots method. The pyrolysis behavior of macauba endocarp was modeled with three independent parallel reactions, describing the devolatilization of pseudo-hemicellulose, pseudo-cellulose and pseudo-lignin, with average activation energies of 90.2 − 99.5, 113.6 − 123.9 and 153.0 − 167.3 kJ mol−1, respectively. Based on the pre-exponential factors, the devolatilization of both pseudo-hemicellulose and pseudo-cellulose occurred through surface reactions (≤ 109 min−1), while pseudo-lignin devolatilized through a simpler chemistry reaction (> 109 min−1). The master-plots method results showed that the devolatilization of pseudo-hemicellulose and pseudo-cellulose followed R-type models, while the devolatilization of pseudo-lignin followed an F-type model. The thermodynamic analysis indicated that macauba endocarp is a viable feedstock for bioenergy production. The summative kinetic expression proposed from the kinetic results was able to reproduce and predict with excellence the experimental behavior of macauba endocarp pyrolysis (R2 > 0.99 and Fit > 95.50%). This work's insights provide a new reference for future applications of macauba endocarp as an attractive and environmentally friendly alternative for bioenergy production.

Controlled copolymerization of 1‐octene and butyl methacrylate via RAFT and their nonisothermal model‐free thermokinetic decomposition study

ABSTRACTReversible addition fragmentation chain transfer (RAFT) copolymerization of 1‐octene and butyl methacrylate (BMA) was carried out for the first time using 4‐cyano‐4‐(phenylcarbonothioylthio)pentanoic acid as RAFT agent in N,N′‐dimethyl formamide. Poly(1‐octene‐co‐BMA) copolymers with well‐controlled molecular weights and narrow molecular weight distribution were obtained throughout the polymerization. The copolymers have been well characterized by different analytical techniques such as SEC, FT‐IR, NMR, SEM, AFM, XRD, and TG analyses. FT‐IR and NMR analyses confirmed the synthesis of poly(1‐octene‐co‐BMA) copolymers. SEM and AFM analyses demonstrated the wavy‐lamellar morphological structure of the copolymers. Thermogravimetric analysis revealed good thermal stability of poly(1‐octene‐co‐BMA) copolymers synthesized via RAFT mediated polymerization. The thermokinetic parameters were evaluated by adopting model‐free methods of Friedman and Flynn–Wall–Ozawa using the nonisothermal thermogravimetric data. The multivariate nonlinear regression analysis established the most appropriate kinetic model and the corresponding kinetic parameters of thermal decomposition of poly(1‐octene‐co‐BMA) copolymers were also calculated. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2093–2103

Kinetic Analysis of Nonisothermal Decomposition of Acetyl Ferrocene

ABSTRACTThe work deals with thermal decomposition of acetyl ferrocene in nitrogen atmosphere based on nonisothermal thermogravimetry. It presents a mathematical analysis of nonisothermal thermogravimetric data using multiheating rates to estimate reaction kinetic parameters. Model free (integral isoconversional) methods are employed to analyze the thermogravimetric data. The decomposition is a multistep process. The activation energy Eα of decomposition is conversion (α) dependent. The average values of activation energy are Eα = 49.87, 106.28, and 183.35 kJ mol−1 for three major steps of decomposition. The most probable reaction mechanism function, g(α), for thermal reactions has been identified by the master plot method, and the stepwise reaction mechanisms are found to be different for different steps. The estimated values of the activation energy Eα and g(α) have been utilized in the determination of the reaction rate Aα of thermal decomposition. The α‐dependent reaction rate values are determined and are found to lie in the range of 5.2 × 105 to 3.2 × 104 min−1, 1.7 × 1015 to 7.8 × 106 min−1, and 3.8 × 108 to 1.4 × 107 min−1 for three different steps. Based on the values of Eα, g(α), and Aα, the thermodynamic triplets (ΔS, ΔH, ΔG) associated with the decomposition reactions have been estimated. Estimated kinetic parameters have been used to construct the conversion curves, and those have been successfully compared with the experimentally observed ones.

Thermal degradation of ceramic slurry-coated polyurethane foam used in making reticulated porous SiC ceramics

A 25-μm-thick ceramic slurry-coated 12 ppi (pores per linear inch) polyurethane foam suitable for synthesis of oxide-bonded reticulated porous SiC ceramics was analysed by the thermal analysis techniques (thermogravimetry and differential thermal analysis) up to 700 °C in air to investigate the polymer degradation reactions associated with the pyrolysis stage of the fabrication process. The kinetic parameters of the polymer degradation reactions were determined using the non-isothermal thermogravimetric data, and the degradation mechanism was evaluated. The effects of slurry coating on the foam degradation process were discussed, and slurry coating on foam was found to have insignificant effects on PUF degradation reactions.

Thermal Decomposition Behavior during Combustion of Hydrothermally Treated MSW by Thermogravimetric Analysis

This research is intended to study fuel property and thermal decomposition behavior of hydrothermally treated municipal solid waste (HTT-MSW) during combustion. In the experiment, simulated MSW was used as a raw material (Raw-MSW) to produce solid biofuels at the hydrothermal reaction temperature of 180, 200, and 220 ºC for 30 min by a lab-scale autoclave. The results showed that the higher reaction temperature in the experiment increased the heating value of the product. Before the HTT process, the Raw-MSW has 20 MJ/kg of heating value, after processed, the energy density was increased to 21.8, 26.4, 31.4 MJ/kg for 180 to 220 ºC respectively. From thermogravimetric analysis result (TGA), mass loss profile of Raw-MSW and HTT-MSW showed two major decomposition peaks and the effect of HTT on combustion was that the decomposition profile became smoother. From kinetics study on non-isothermal thermogravimetric data, the activation energy (E) of HTT-MSW was higher than that of the Raw-MSW and the E values were around 35 to 80 kJ/mol for the Raw-MSW and HTT-MSW.

Investigation of Tabas anthracite coal devolatilization: Kinetics, char structure and major evolved species

The pyrolysis of low-volatile Tabas anthracite coal was investigated by thermogravimetric technique (TGA) in the temperature range from ambient to 1100°C under non-isothermal heating conditions (1.5, 3, and 7°C/min heating rates). Higher heating rates showed a small retarding effect on devolatilization toward higher temperatures. Iso-conversional method was used for the kinetic study of non-isothermal Thermogravimetric data. Activation energy calculated for coal conversion of 20–80% was about 319kJ/mol which may be a result of stable ordered structure of this type of coal. Analysis of evolved gases by Fourier transform infrared spectrometry (FTIR) in 7°C/min heating rate was conducted for the identification of the gaseous species and their evolution profiles during coal thermal degradation. H2O, CO, SO2, CO2, CH4 were respectively major gases detected in FTIR while C2H6 and H2 were also detected. From X-ray photoelectron spectroscopy (XPS) Cls spectrum, major functional group changes on raw and devolatilized coal surfaces are found to be an increase in ether and carbonyl bond intensity and a decrease in carboxylic bond. It was also showed in XPS wide energy spectra that C atomic percent increased after pyrolysis while O and S decreased.

Thermal Decomposition Reaction of Ferrocene in the Presence of Oxalic Acid

Thermal decomposition of ferrocene [(C5H5)2Fe] in the presence of oxalic acid [(COOH)2·2H2O] samples—prepared by grinding the mixtures of ferrocene and oxalic acid at different weight ratios—is reported in this work. It presents a mathematical analysis of nonisothermal thermogravimetric data using multiheating rates to estimate reaction kinetics as well as thermodynamic parameters. Model-free (integral isoconversional) methods are employed to analyze thermogravimetric data. The most probable reaction mechanisms for thermal reactions have been identified. Based on the values of the activation energy Eα* and reaction rate Aα for different steps of decomposition, the values of ΔS*, ΔH*, and ΔG* for the formation of activated complex from the precursor are estimated. Besides, this work has proposed reaction pathways indicating the formation of hematite (α-Fe2O3) as the solid end-product of thermal decomposition of the samples.

Kinetic analysis of non-isothermal solid-state reactions: multi-stage modeling without assumptions in the reaction mechanism.

A novel non-linear regression method for modeling non-isothermal thermogravimetric data is proposed. Experiments for several heating rates are analyzed simultaneously. The method is applicable to complex multi-stage processes when the number of stages is unknown. Prior knowledge of the type of kinetics is not required. The main idea is a consequent estimation of parameters when the overall model is successively changed from one level of modeling to another. At the first level, the Avrami-Erofeev functions are used. At the second level, the Sestak-Berggren functions are employed with the goal to broaden the overall model. The method is tested using both simulated and real-world data. A comparison of the proposed method with a recently published 'model-free' deconvolution method is presented.

Kinetics Modeling of Low-Rank Coal Pyrolysis Based on a Three-Gaussian Distributed Activation Energy Model (DAEM) Reaction Model

A three-Gaussian distributed activation energy model (DAEM) reaction model (3-DAEM) was successfully applied for the kinetics study on the thermal pyrolysis of four types of low-rank coals, based on their nonisothermal thermogravimetric data. It is found that 3-DAEM was feasible for the analysis of coal pyrolysis process, which can be divided into three stages, using the second derivative method for thermogravimetry (TG) curves and the Peakfit software for differential thermogravimetry (DTG) curves. Calculated kinetic parameters, including three mean activation energies (E0), three standard deviations (σE), and two weights (w), were used to predict the pyrolysis process, and the results agreed well with the experimental data. Furthermore, the kinetics parameters were found to have a strong relationship with the DTG curve shape and especially with the coal property. These results indicated that 3-DAEM provided a good way to process thermogravimetric analysis (TGA) data and understand the pyrolysis mechanis...

Combustion Kinetics of Biochar from Fast Pyrolysis of Pine Sawdust: Isoconversional Analysis

Non-isothermal thermogravimetric data were used to evaluate the Arrhenius parameters (activation energy and the pre-exponential factor) of the combustion of biochar. The biochar was produced as a byproduct from the fast pyrolysis of pine sawdust particle. The isoconversional methods (Kissinger–Akahira–Sunose and Flynn–Wall–Ozawa method) were used for evaluating the activation energy and the kinetic model function f(α), which was determined by using the master plot method. The effective activation energy for combustion of biochar was 212.524 kJ mol–1 in the conversion range of 0.15–0.85. The results showed that the most probable mechanism is the simple order reaction model function, f(α) = (1 – α)3.3, and A = 6.20 × 1012 s–1.

Comparative investigation on non-isothermal kinetics for thermo-degradation of lignocellulosic substrate and its chlorinated derivative in atmospheres with CO2 participation

Investigations were launched under atmospheres of different N2/CO2 ratios for thermo-degradation of lignocellulosic biomass and its chlorinated derivative that typically contains 10wt.% poly(vinyl chloride) (PVC) over thermogravimetric analysis.Two degradation stages were found where CO2 was inert in stage one but changed to be reactive in stage two. Lignocellulosics were less reactive than their chlorinated derivatives. Non-isothermal thermogravimetric data were used for evaluating kinetics using Ozawa–Flynn–Wall and Vyazovkin methods. The values of apparent activation energy in stage one were 200–250kJ/mol with less variance but varied greatly in stage two for different scenarios concerning CO2 proportion and PVC presence. These values were used to determine the reaction mechanism of each stage by master-plots method. Most processes were kinetically characterized by diffusion and reaction order models. The results afford a theoretical groundwork for the resourceful utilization of lignocellulosics derived from municipal activities and the development of their thermochemical conversion systems.

Kinetic study on the pyrolysis behavior of Huadian oil shale via non-isothermal thermogravimetric data

Oil shale pyrolysis is normally extremely complicated because many reactive processes simultaneously occur and different products are therefore continuously generated and serve as a new reactant, as a multi-stage processes with competing or parallel reactions. To probe deeply into the pyrolysis kinetics of Huadian oil shale, we have employed multi-stage parallel reaction model and bi-Gaussian distribution method to fit the non-isothermal thermogravimetric data. Friedman, Flynn–Wall–Ozawa, and Kissinger–Akahira–Sunose methods were utilized to estimate activation energy, and two master plots methods were introduced to establish kinetic models. Two reactions were involved in devolatilization of organic matter in oil shale, and the Reaction II was a principal process of Stage II and dominated kinetic property of overall Stage II. The heating rate had some impact on the pyrolysis process but exerted little influence on kinetic parameters. The comparison of these results indicated the inherent property and thermal stability of oil shale pyrolysis.

Oxy-combustion of corn, sunflower, rape and microalgae bioresidues and their blends from the perspective of thermogravimetric analysis

Thermogravimetric analysis was used to study and compare the oxy-combustion of different blends of corn bioresidues with sunflower, rape and algae bioresidues. Non-isothermal thermogravimetric data were used to obtain the oxy-combustion kinetics of these bioresidues. This paper reports on the application of the Vyazovkin and Ozawa-Flynn-Wall isoconversional methods to evaluate the kinetic parameters (energy activation, pre-exponential factor and reaction order) in the oxy-combustion of the bioresidues studied.The activation energy obtained from corn oxy-combustion (E∼168.9 kJ mol−1) was lower than that from the blends (corn-sunflower, E∼189.0 kJ mol−1 and corn-microalgae, E∼201.9 kJ mol−1) whereas the activation energy obtained from the corn-rape blend was the lowest (E∼155.9 kJ mol−1).Both the Vyazovkin and Ozawa-Flynn-Wall methods yielded similar results.

Differences between combustion and oxy-combustion of corn and corn–rape blend using thermogravimetric analysis

Nowadays, diverse technologies to produce electricity based on bioresidues are investigated in order to reduce the external energy dependence of occidental countries, as Spain.Thermogravimetric analysis was used to study and compare the combustion and oxy-combustion of corn, rape and a corn–rape blend. Non-isothermal thermogravimetric data were used to obtain the reaction kinetics of these bioresidues. This paper reports on the application of the Vyazovkin and Ozawa–Flynn–Wall isoconversional methods for the evaluation of kinetic parameters (energy activation, pre-exponential factor and order of reaction) for the oxidation of the biomasses studied.Differences were found in the TG curves in accordance with the proximate analysis results for the cellulose, hemicellulose, lignin, volatile matter and fixed carbon content of biomasses and the atmosphere of the reaction. The presence of CO2 in the atmosphere instead of N2 was also discussed.The activation energy obtained from corn (153.0kJ/mol) combustion was lower than that obtained from corn oxy-combustion (168.6kJ/mol). However, corn–rape blend oxidation was more favourable in the presence of CO2 (E ~155.3kJ/mol) than in N2 (E ~155.9kJ/mol). Both Vyazovkin and Ozawa–Flynn–Wall methods yielded similar results.

Physical-chemical characterization of biomass samples for application iin pyrolysis process

The use of lignocellulosic biomass as an energy source has considerably increased. Due to the diverse natures of biomass materials, their properties widely range and exhibit different behaviors in thermal processes. The most important properties that provide information about a fuel are heating values, ash composition, proximate (determination of moisture, ash, volatile and fixed carbon content), and ultimate analysis (C, H, N, S and O composition). Moreover, the kinetic study of the thermal behavior of a fuel can be useful for the understanding of the complex decomposition process of each material. This study focuses on the physical-chemical characterization of six lignocellulosic biomasses, namely coffee husk, tucuma seed, sugar cane bagasse, peanut shell, rice husk and pine sawdust, widely available in Brazil. A thermogravimetric analyzer was used to study their decomposition behavior in a pyrolytic environment. Non-isothermal thermogravimetric data were used and the application of a model-free isoconversional method enabled the evaluation of the activation energy (Ea) of the biofuels. The curves also show that the behavior during thermal decomposition varies from one biomass to another and these differences imply the importance of a comprehensive characterization study of fuels for the development and optimization of reactors. The knowledge on biomass properties enables the prediction of environmental impacts and technical aspects related to thermal processes. Therefore, thermal decomposition behavior is a consequence of the feedstock physical-chemical characteristic, which also provides valuable information regarding features of the complex reactions that occur throughout the pyrolysis of the biomass.

Pyrolysis and combustion model of oil sands from non-isothermal thermogravimetric analysis data

Thermogravimetric (TG) data of oil sand obtained at Engineering Research Center of Oil Shale Comprehensive Utilization were studied to evaluate the kinetic parameters for Indonesian oil sand samples. Experiments were carried out at heating rates of 5, 15, and 25 °C min−1 in nitrogen, 10, 20, and 50 °C min−1 in oxygen atmosphere, respectively. The extent of char combustion was found out by relating TG data for pyrolysis and combustion with the ultimate analysis. Due to distinct behavior of oil shale during pyrolysis, TG curves were divided into three separate events: moisture release, devolatilization, and evolution of fixed carbon/char, where for each event, kinetic parameters, based on Arrhenius theory, were calculated. Coats–Redfern method, Flynn–Wall–Ozawa method, and distributed activation energy model method have been used to determine the activation energies of degradation. The methods are compared with regard to their characteristics and the ease of interpretation of the thermal kinetics. Activation energies of the samples were determined by three different methods and the results are discussed.

A Non-isothermal Thermogravimetric Kinetic Analysis of Malaysian Sewage Sludge

Dewatered sewage sludge is one of the largest contributors of waste material in Malaysia and it indirectly elevates local environmental problems. Previous studies have indicated sewage sludge as a potential alternative fuel based on its higher heating values. To explore sewage sludge as an alternative solid fuel will not only address energy demand issues, it will also mitigate long term disposal problems related with the waste material. Further information on combustion characteristics of this material is required before any links to power generation applications can be established. In this work the combustion characteristics of Malaysian sewage sludge was studied by means of thermogravimetric analysis (TGA) under different heating rates (10, 20 30 and 40 K/min). Non-isothermal thermogravimetric data were used to assess the kinetics of the combustion of sewage sludge by the application of Ozawa-Flynn- Wall and Vyazovkin kinetic models. The average activation energies were found to be 82 and 79 kJ/ mol respectively. The average reaction order corresponding to sewage sludge combustion was 0.11.

New logarithmic equation of temperature integral for modelling non-isothermal reactions

This article proposes a new logarithmic approximate formula of the Arrhenius temperature integral p(u) for non-isothermal analysis using the Solver algorithm. The proposed formula is presented as and the values for a, b and c are 0.69038, 1.71975 and 1.01249, respectively, for 0.45891, 1.85919 and 1.00275, respectively, for and 0.27341, 1.93235 and 1.00060, respectively, for The validity of the proposed Arrhenius temperature integral formula has been tested by investigating the thermal decomposition kinetics of acrylonitrile–butadiene–styrene (ABS). The activation energy and the pre-exponential factor determined by the proposed formula are 48.7385 kcal mol−1 and 2.6 × 1016 s−1, respectively. The reaction model of ABS thermal decomposition obtained with the method of master plots indicates that the phase boundary reaction model best describes the thermal decomposition reaction of ABS. The accuracy of the proposed Arrhenius temperature integral formula has also been tested by numerical analysis, and deviations from numerical values were compared with those of several previously published approximation formulae. The results show that the proposed formula is superior and is nearly ideal for estimating kinetic parameters from non-isothermal thermogravimetric data.