Novel approach to thermal degradation kinetics of gypsum: application of peak deconvolution and Model-Free isoconversional method

In the present work, the thermal stability, changes in chemical structure during thermal degradation, and the kinetics of thermal degradation of a phenolic foam were studied. An 8.5 wt% of Pinus radiata wood flour reinforcement was added to the phenolic foam. A commercial phenolic resol was used as the matrix for the foam. The wood flour-reinforced foam showed a structure similar to the phenolic foam according to the Fourier transform infrared spectroscopy results. The wood flour increased the thermal stability of the phenolic foam in the first stage of thermal degradation ( T 5%), decreased it in the second step ( T 25%), and negligibly influenced the final stage. The activation energies of the degradation processes of the studied materials were obtained by the Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa model-free kinetic methods and a 2-Gaussian distributed activation energy model. The values of the activation energies obtained by the model-free kinetic methods for the first degradation stage of the phenolic foams were in a range between 110 and 170 kJ mol−1, whereas for the wood flour it was 162 kJ mol−1 for almost all of the conversion range of its main degradation stage. The applied models showed good fits for all the materials, and the activation energies calculated were in agreement with the values found in the literature.

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Photoisomerization and thermal degradation kinetics of poly(ether–ester)s containing azomethine moiety in the main chain

High Performance Polymers ◽

10.1177/0954008319850614 ◽

2019 ◽

Vol 32 (1) ◽

pp. 47-58 ◽

Cited By ~ 1

Author(s):

R Vini ◽

SC Murugavel

Keyword(s):

Thermal Degradation ◽

Main Chain ◽

Degradation Kinetics ◽

Uv Spectroscopy ◽

Thermal Degradation Kinetics ◽

Spectroscopic Techniques ◽

Isothermal Model ◽

Model Free ◽

Kinetics Of ◽

Ether Ester

Poly(ether–ester)s containing azomethine group in the main chain were synthesized by solution polycondensation of 4,4′-bis(3-hydroxypropyloxy)- N-benzylidene aniline with adipoyl and terephthaloyl diacid chlorides. The synthesized poly(ether–ester)s were characterized by Fourier transform infrared and proton, and carbon-13 nuclear magnetic resonance spectroscopic techniques. Thermal properties were studied using thermogravimetric analysis (TGA) and differential scanning calorimetry. Thermal degradation kinetics of poly(ether–ester)s were characterized by TGA at various heating rates (5°C min−1, 10°C min−1, and 20°C min−1). The apparent activation energy for the degradation of both the polymers was determined by three different non-isothermal model-free kinetics methods (Friedmann, Flynn–Wall Ozawa, and Kissinger–Akahira–Sunose). The photoisomerization property was examined with ultraviolet (UV) spectroscopy, and the polymer PEE1 showed a rate of trans to cis isomerization ranging 10–20 s, whereas reverse process took around 100 min in solution. UV studies suggested that this material may be used in the field of rewritable applications.

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Thermal stability and thermal degradation kinetics (model-free kinetics) of nanocomposites based on poly (lactic acid)/graphene: the influence of functionalization

Polymer Bulletin ◽

10.1007/s00289-015-1325-4 ◽

2015 ◽

Vol 72 (5) ◽

pp. 1095-1112 ◽

Cited By ~ 19

Author(s):

Pedram Manafi ◽

Ismaeil Ghasemi ◽

Mohammad Karrabi ◽

Hamed Azizi ◽

Mohammad Reza Manafi ◽

...

Keyword(s):

Thermal Stability ◽

Lactic Acid ◽

Thermal Degradation ◽

Degradation Kinetics ◽

Kinetics Model ◽

Thermal Degradation Kinetics ◽

Poly Lactic Acid ◽

Model Free ◽

Model Free Kinetics ◽

Kinetics Of

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Thermal degradation kinetics of a lignin particle-reinforced phenolic foam

Journal of Cellular Plastics ◽

10.1177/0021955x20932889 ◽

2020 ◽

pp. 0021955X2093288

Author(s):

Juan Carlos Domínguez ◽

Belén Del Saz-Orozco ◽

Mercedes Oliet ◽

M Virginia Alonso ◽

Francisco Rodriguez

Keyword(s):

Activation Energy ◽

Thermal Degradation ◽

Kinetic Parameters ◽

Degradation Kinetics ◽

Degradation Process ◽

Activation Energies ◽

Thermal Degradation Kinetics ◽

Model Free ◽

Predicted Values ◽

Kinetics Of

In the present work, the thermal degradation kinetics of a phenolic (PF) and lignin particle-reinforced phenolic (LRPF) foam and the lignin used as the reinforcement (LR) were studied. The activation energies of the degradation processes were obtained using a discrete distributed activation energy model (discrete DAEM) and the Vyazovkin model-free kinetic (MFK) method. The discrete DAEM was validated by comparing the predicted values with the data obtained at 8 °C min−1. Heating ramps of 6 and 12 °C min−1 were used to calculate the kinetic parameters through the model. The effect of the reinforcement on the kinetics of the LRPF was studied by comparison with the results obtained for the PF. For reactions with non-zero mass fractions, the activation energies of the PF were in the range between 79.9 and 177.6 kJ mol−1, and the activation energy for the LRPF ranged from 91 to 187 kJ mol−1. For the LR, the activation energy values were in a narrower range than for the foams: 150–187 kJ mol−1. The degradation process of the LRPF was modified due to the use of LR: the range of activation energy for LRPF was between the ranges for the PF and LR. The activation energy dependence on conversion was also calculated using the Vyazovkin method and compared with the DAEM results; no compensation effect for the kinetic parameters was found.

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

Journal of Composite Materials ◽

10.1177/00219983211008202 ◽

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.

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Thermal Degradation Kinetics and Modeling Study of Ultra High Molecular Weight Polyethylene (UHMWP)/Graphene Nanocomposite

Molecules ◽

10.3390/molecules26061597 ◽

2021 ◽

Vol 26 (6) ◽

pp. 1597

Author(s):

Iman Jafari ◽

Mohamadreza Shakiba ◽

Fatemeh Khosravi ◽

Seeram Ramakrishna ◽

Ehsan Abasi ◽

...

Keyword(s):

Thermal Stability ◽

Molecular Weight ◽

Thermal Degradation ◽

High Molecular Weight ◽

Degradation Kinetics ◽

Graphene Nanosheets ◽

Thermal Degradation Kinetics ◽

Graphene Nanocomposites ◽

Kinetics Of ◽

Ultra High Molecular Weight

The incorporation of nanofillers such as graphene into polymers has shown significant improvements in mechanical characteristics, thermal stability, and conductivity of resulting polymeric nanocomposites. To this aim, the influence of incorporation of graphene nanosheets into ultra-high molecular weight polyethylene (UHMWPE) on the thermal behavior and degradation kinetics of UHMWPE/graphene nanocomposites was investigated. Scanning electron microscopy (SEM) analysis revealed that graphene nanosheets were uniformly spread throughout the UHMWPE’s molecular chains. X-Ray Diffraction (XRD) data posited that the morphology of dispersed graphene sheets in UHMWPE was exfoliated. Non-isothermal differential scanning calorimetry (DSC) studies identified a more pronounced increase in melting temperatures and latent heat of fusions in nanocomposites compared to UHMWPE at lower concentrations of graphene. Thermogravimetric analysis (TGA) and derivative thermogravimetric (DTG) revealed that UHMWPE’s thermal stability has been improved via incorporating graphene nanosheets. Further, degradation kinetics of neat polymer and nanocomposites have been modeled using equations such as Friedman, Ozawa–Flynn–Wall (OFW), Kissinger, and Augis and Bennett’s. The "Model-Fitting Method” showed that the auto-catalytic nth-order mechanism provided a highly consistent and appropriate fit to describe the degradation mechanism of UHMWPE and its graphene nanocomposites. In addition, the calculated activation energy (Ea) of thermal degradation was enhanced by an increase in graphene concentration up to 2.1 wt.%, followed by a decrease in higher graphene content.

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