Multi‐scale simulations of the thermal degradation of thin wooden plates: Evaluation of two kinetic mechanisms

2021 ◽  
Author(s):  
Guillaume Gerandi ◽  
Virginie Tihay‐Felicelli ◽  
Frederic Morandini ◽  
Paul‐Antoine Santoni
Keyword(s):  
Thermal Degradation ◽  
Multi Scale ◽  
Kinetic Mechanisms

Degradation of Polymers

1962 ◽  
Vol 35 (5) ◽  
pp. 1157-1221 ◽  
Author(s):  
Leo A. Wall ◽  
Joseph H. Flynn
Keyword(s):  
Ionizing Radiation ◽  
Thermal Degradation ◽  
Natural Rubber ◽  
Ultraviolet Light ◽  
Recent Literature ◽  
Chain Scission ◽  
Experimental Results ◽  
Gel Formation ◽  
Vinyl Polymers ◽  
Kinetic Mechanisms

Abstract Recent literature pertaining to both the theoretical aspects and experimental results of the degradation of polymers by heat and radiation is reviewed and critically evaluated. Theories of random and chain thermal degradation of vinyl polymers and co-polymers are reviewed. The degradation of polymethacrylates, polyacrylates, poly-α-methylstyrene, polyolefins, polystyrene, other vinyl polymers, cellulose, polyesters, polyamides, dienes, natural rubber, and copolymers are discussed in the light of these theories. The thermodynamics and energetics of the degradation of these polymers is also reviewed. Chain scission, crosslinking, and gel formation and the kinetic mechanisms of these processes which take place during degradation of polymers by ionizing radiation and ultraviolet light are included. Degradative, rather than synthetic, effects are emphasized in the discussion.

Thermal degradation of epoxy resin grafted with polyurethane

2014 ◽  
Vol 21 (1) ◽  
pp. 7-13 ◽  
Author(s):  
Zhenjiang Song ◽  
Jianliang Xie ◽  
Peiheng Zhou ◽  
Jianing Peng ◽  
Xin Wang ◽  
...  
Keyword(s):  
Thermal Degradation ◽  
Epoxy Resin ◽  
Model Fitting ◽  
Hydroxyl Groups ◽  
Degradation Model ◽  
Reactive Process ◽  
Fitting Method ◽  
Kinetic Mechanisms ◽  
Two Stages ◽  
Scanning Electron

AbstractEpoxy resin grafted with polyurethane was synthesized and characterized through a series of tests. The grafting reactive process between the pendant secondary hydroxyl groups on the side chains of epoxy resin and the isocyanate groups of pre-polyurethane were investigated by Fourier transform infrared spectroscopy. Thermal behavior of the grafted epoxy resin was investigated by thermogravimetric analysis within 40–500°C. The degradation of grafted epoxy resin involved two stages. Microstructures of the polyurethane section and grafted epoxy resin were observed by field emission scanning electron microscopy. Model fitting method was employed to calculate the thermal degradation model of grafted epoxy resin. In this paper, 15 typical kinetic mechanisms were introduced into the model fitting method, such as Coats-Redfern method and Achar-Brindley-Sharp-Wendworth method, to obtain the kinetic function of thermal degradation for grafted epoxy resin.

scholarly journals Kinetics of Nonisothermal Degradation of Some Polymer Composites: Change of Entropy at the Formation of the Activated Complex from the Reagents

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Sevdalina Turmanova ◽  
Svetlana Genieva ◽  
Lyubomir Vlaev
Keyword(s):  
Thermal Degradation ◽  
Polymer Composites ◽  
Nitrogen Atmosphere ◽  
Rice Husks ◽  
Kinetic Mechanisms ◽  
Ethylene Copolymer ◽  
Kinetics Of Degradation ◽  
Rice Husks Ash ◽  
Kinetics Of ◽  
Activated Complex

Studying the nonisothermal kinetics of degradation of rice husks in air or nitrogen atmosphere, polypropylene and tetrafluoroethylene-ethylene copolymer filled with different quantities of rice husks flour or the products of its thermal degradation, namely “white” or “black” rice husks ash, a linear dependence was observed between the and , known as the kinetic compensation effect or theta rule. A linear relationship was also established between and the change of the entropy for the formation of the activated complex from the reagents. These dependences are related to the assumption of identical kinetic mechanisms of thermal degradation of the composites studied. The negative values of obtained show that the activated complex is a “more organized” structure than the initial reactants and that these reactions may be classified as “slow” ones. It may be concluded that the products of the thermal degradation of rice husks in a fluidized bed reactor can successfully replace the more expensive synthetic fillers to obtain different polymer composites. These polymer composites can lead to the futuristic “organic-inorganic hybrid materials” with specific properties.

scholarly journals Multi-scale experimental investigations of the thermal degradation of pine needles

2016 ◽  
Vol 41 (6) ◽  
pp. 654-674 ◽  
Author(s):  
T. Fateh ◽  
F. Richard ◽  
J. Zaida ◽  
T. Rogaume ◽  
P. Joseph
Keyword(s):  
Thermal Degradation ◽  
Pine Needles ◽  
Experimental Investigations ◽  
Multi Scale

scholarly journals Comparative Thermal Degradation Behaviors and Kinetic Mechanisms of Typical Hardwood and Softwood in Oxygenous Atmosphere

Processes ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 1598
Author(s):  
Xiaokang Xu ◽  
Renming Pan ◽  
Ruiyu Chen
Keyword(s):  
Activation Energy ◽  
Thermal Degradation ◽  
Beech Wood ◽  
Degradation Process ◽  
Heating Rates ◽  
Experimental Profile ◽  
Kinetic Triplet ◽  
Kinetic Mechanisms ◽  
External Conditions ◽  
Degradation Behaviors

In order to utilize woody biomass effectively for bioenergy and chemical feedstocks, the comparative thermal degradation behaviors and kinetic mechanisms of typical hardwood (beech wood) and softwood (camphorwood) were studied at various heating rates in air. The Kissinger-Akahira-Sunose approach combined with the Coats-Redfern approach was employed to estimate the kinetic triplet. Softwood degradation began and ended at lower temperatures than hardwood. Compared with softwood, the maximal reaction rate of hardwood was greater and occurred in the higher temperature region. Two decomposition regions were determined by the variation of activation energy, and the dividing point was α = 0.6 and α = 0.65 for hardwood and softwood, respectively. Moreover, the average activation energy of hardwood was larger than that of softwood during the whole decomposition process. The thermal degradation process occurring in region 1 was dominated by the Avrami-Erofeev and 3D diffusion models for hardwood and softwood, respectively. Furthermore, the kinetic modeling results showed good consistency between the experimental and simulated curves under 5, 15, 20, and 40 K/min. It is noted that the thermogravimetric experimental profile under 20 K/min was not used for estimating the kinetic triplet. Besides, the combustion performance of hardwood is superior to softwood under the same external conditions (heating rate and atmosphere).

scholarly journals Thermal Degradation of β-Carotene from Macauba Palm: Mathematical Modeling and Parameter Estimation

2021 ◽  
Vol 10 (1) ◽  
pp. 161-172
Author(s):  
Pedro Prates Valério ◽  
Amanda Lemette Brandão ◽  
Jesus Maria Frias Celayeta ◽  
Erika Cristina Cren
Keyword(s):  
Thermal Degradation ◽  
Degradation Kinetics ◽  
Reaction Rates ◽  
Total Carotenoids ◽  
Kinetic Mechanisms ◽  
Essential Unity ◽  
One Step ◽  
Available Information ◽  
First Time ◽  
Kinetics Of

Worldwide, there is a current need for new sources of vegetable oils. The natural content of total carotenoids in Acrocomia aculeata palm oil (up to 378 µg.g-1) surpasses that of many other tropical fruits, making it one of its main compositional characteristics. As far as can be verified, there is no available information on the degradation kinetics of carotenoids for A. aculeata oil, which is required to describe reaction rates and to predict changes that can occur during food processing. The present study considered prediction abilities that have emerged with the use of specific kinetic data and procedures to understand thermal processing better, as an essential unity operation. Two kinetic mechanisms were proposed to describe the overall thermal degradation of carotenoids in the oil; the first one consists of three reaction steps while the other presents only one-step reaction. Mass balance equations were numerically solved by a Backward Differentiation Formula technique. The kinetic parameters from both models were estimated through a hybrid optimisation method using the Particle Swarm Optimization and the Gauss-Newton method, followed by statistical analyses. The model with more than one reaction was shown to be overparameterized and was discarded. The model with a single reaction was highly suited to handle the experimental data available, and the dependency of its rate constant on temperature was expressed according to Arrhenius law. As far we know, this is the first time the kinetics of carotenoids thermal degradation in A. aculeata oil is investigated through modelling simulation.

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