Thermal properties and thermal degradation kinetics of phenolic and wood flour-reinforced phenolic foams

2016 ◽  
Vol 51 (1) ◽  
pp. 125-138 ◽  
Author(s):  
JC Domínguez ◽  
B del Saz-Orozco ◽  
M Oliet ◽  
MV Alonso ◽  
F Rodriguez
Keyword(s):  
Thermal Stability ◽  
Thermal Degradation ◽  
Degradation Kinetics ◽  
Wood Flour ◽  
Activation Energies ◽  
Thermal Degradation Kinetics ◽  
Kinetic Methods ◽  
Model Free ◽  
Phenolic Foam ◽  
Kinetics Of

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.

Thermal degradation kinetics of a lignin particle-reinforced phenolic foam

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.

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.

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

Molecules ◽  
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.

Thermo-oxidative and thermal degradation kinetics of silica/polymethyl methacrylate composites with electrostatic interaction phase interfaces

2019 ◽  
Vol 39 (2) ◽  
pp. 105-116 ◽  
Author(s):  
Hongyan Li ◽  
Yongqiang Fu ◽  
Hongli Liu ◽  
Cong Sun ◽  
Ruyi Li ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermal Degradation ◽  
Polymethyl Methacrylate ◽  
Electrostatic Interaction ◽  
Degradation Kinetics ◽  
Thermal Degradation Kinetics ◽  
Degradation Kinetic ◽  
Further Development ◽  
Kinetics Of ◽  
Insulation Performance

AbstractThe thermo-oxidative and thermal degradation kinetic parameters of polymethyl methacrylate-methacryloxyethyltrimethyl ammonium chloride/silica aerogel composites (PMMA-MTC/SA) were investigated in this paper and were compared with the thermal stability and thermal conductivity of different types of composites. As a composite with electrostatic interaction, the thermo-oxidative and thermal degradation activation energies (E) of PMMA-MTC/SA were 173.97 and 188.05 kJ/mol, respectively. The results indicated that the electrostatic interaction could indeed enhance the thermal stability of silica/polymethyl methacrylate composites on the premise of good mechanical properties and heat insulation performance. It is of great significance for the further development of silica-based thermal insulation composites.

Non-isothermal crystallization and thermal degradation kinetics of MXene/linear low-density polyethylene nanocomposites

e-Polymers ◽  
2017 ◽  
Vol 17 (5) ◽  
pp. 373-381 ◽  
Author(s):  
Xinxin Cao ◽  
Mengqi Wu ◽  
Aiguo Zhou ◽  
You Wang ◽  
Xiaofang He ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Thermal Degradation ◽  
Isothermal Crystallization ◽  
Degradation Kinetics ◽  
Thermal Degradation Kinetics ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Kinetics Of

AbstractA novel two-dimensional material MXene was used to synthesize nanocomposites with linear low-density polyethylene (LLDPE). The influence of MXene on crystallization and thermal degradation kinetics of LLDPE was investigated. Non-isothermal crystallization kinetics was investigated by using differential scanning calorimetry (DSC). The experimental data was analyzed by Jeziorny theory and the Mo method. It is found that MXene acted as a nucleating agent during the non-isothermal crystallization process, and 2 wt% MXene incorporated in the nanocomposites could accelerate the crystallization rate. Findings from activation energy calculation for non-isothermal crystallization came to the same conclusion. Thermal gravity (TG) analysis of MXene/LLDPE nanocomposites was conducted at different heating rates, and the TG thermograms suggested the nanocomposites showed an improvement in thermal stability. Apparent activation energy (Ea) of thermal degradation was calculated by the Kissinger method, and Ea values of nanocomposites were higher than that of pure LLDPE. The existence of MXene seems to lead to better thermal stability in composites.

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

2019 ◽  
Vol 32 (1) ◽  
pp. 47-58 ◽  
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.

Thermal degradation kinetics of oxo-degradable PP/PLA blends

2018 ◽  
Vol 39 (1) ◽  
pp. 58-67 ◽  
Author(s):  
Dev K. Mandal ◽  
Haripada Bhunia ◽  
Pramod K. Bajpai
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Thermogravimetric Analysis ◽  
Thermal Degradation ◽  
Kinetic Parameters ◽  
Degradation Kinetics ◽  
Nitrogen Atmosphere ◽  
Thermal Degradation Kinetics ◽  
Heating Rates ◽  
Kinetics Of

AbstractIn this article, the influence of polylactide and pro-oxidant on the thermal stability, degradation kinetics, and lifetime of polypropylene has been investigated using thermogravimetric analysis under nitrogen atmosphere at four different heating rates (i.e. 5, 10, 15, and 20°C/min). The kinetic parameters of degradation were studied over a temperature range of 30–550°C. The derivative thermogravimetric curves have indicated single stage and two stage degradation processes. The activation energy was evaluated by using the Kissinger, Kim-Park, and Flynn-Wall methods under the nitrogen atmosphere. The activation energy value of polypropylene was much higher than that of polylactide. Addition of polylactide and pro-oxidant in polypropylene decreased the activation energy. The lifetime of polypropylene has also decreased with the addition of polylactide and pro-oxidant.

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