scholarly journals Thermo-catalytic degradation of PE and UHMWPE over zeolites with different pore systems and textural properties

Cerâmica ◽  
2020 ◽  
Vol 66 (380) ◽  
pp. 379-385
Author(s):  
B. J. B. Silva ◽  
A. C. S. Melo ◽  
D. S. Silva ◽  
L. V. Sousa ◽  
P. H. L. Quintela ◽  
...  
Keyword(s):  
Activation Energy ◽  
Molecular Weight ◽  
Lower Energy ◽  
Textural Properties ◽  
Degradation Process ◽  
Catalytic Degradation ◽  
Ozawa Method ◽  
Heating Rates ◽  
Lower Energy Level ◽  
Ultra High Molecular Weight

Abstract The thermo-catalytic degradation of polyethylene (PE) and ultra-high molecular weight polyethylene (UHMWPE) was studied in the presence of zeolites (ZSM-5, ZSM-22, and ferrierite) with different pore systems and textural properties. The zeolites were physically mixed with polymers in the proportion of 30 wt% and submitted to thermogravimetric analysis at heating rates of 5, 10, 20, and 30 °C.min-1. The activation energy of the degradation process was determined using the Flynn-Wall-Ozawa method. The addition of zeolites to polymers has considerably reduced the temperature of degradation. ZSM-22 demonstrated greater efficiency in the degradation of PE because it has a smaller crystallite size, promoting a shorter diffusional path for the polymer fragments coming from the surface. Ferrierite showed a lower energy level in the degradation of UHMWPE, showing the need for synergy between the accessibility of the structure and acidity of the catalyst to promote the cracking of this polymer.

Non-isothermal degradation kinetics for polycarbonate/ polymethylphenylsilsesquioxane composites

e-Polymers ◽  
2010 ◽  
Vol 10 (1) ◽  
Author(s):  
Jiangbo Wang ◽  
Zhong Xin
Keyword(s):  
Activation Energy ◽  
Thermogravimetric Analysis ◽  
Thermal Degradation ◽  
Flame Retardancy ◽  
Degradation Kinetics ◽  
Degradation Process ◽  
Nitrogen Atmosphere ◽  
Ozawa Method ◽  
Degradation Behaviors ◽  
Thermal Degradation Process

AbstractThe thermal degradation behaviors of PC/PMPSQ (polymethylphenylsilsesquioxane) systems were investigated by thermogravimetric analysis (TGA) under non-isothermal conditions in nitrogen atmosphere. During non-isothermal degradation, Kissinger and Flynn-Wall-Ozawa methods were used to analyze the thermal degradation process. The results showed that a remarkable decrease in activation energy ( E ) was observed in the early and middle stages of thermal degradation in the presence of PMPSQ, which indicated that the addition of PMPSQ promoted the thermal degradation of PC. Flynn-Wall-Ozawa method further revealed that PMPSQ significantly increased the activation energy of PC thermal degradation in the final stage, which illustrated that the PMPSQ stabilized the char residues and improved the flame retardancy of PC in the final period of thermal degradation process

scholarly journals Comparative study of the reaction kinetics of three residual biomasses

BioResources ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. 2891-2905
Author(s):  
Arnaldo Martinez ◽  
Lourdes Meriño ◽  
Alberto Albis ◽  
Jorge Ortega
Keyword(s):  
Activation Energy ◽  
Heating Rate ◽  
Lignin Content ◽  
Cellulose Degradation ◽  
Calorific Value ◽  
Degradation Process ◽  
Proximate Analysis ◽  
Cellulose Content ◽  
Heating Rates ◽  
Biomass Residues

Kinetic analysis for the combustion of three agro-industrial biomass residues (coconut husk, corn husk, and rice husk) was carried out in order to provide information for the generation of energy from them. The analysis was performed using the results of the data obtained by thermogravimetric analysis (TGA) at three heating rates (10, 20, and 30 K/min). The biomass residues were characterized in terms of proximate analysis, elemental analysis, calorific value, lignin content, α-cellulose content, hemicellulose content, and holocellulose content. The biomass fuels were thermally degraded in an oxidative atmosphere. The results showed that the biomass thermal degradation process is comprised of the combustion of hemicellulose, cellulose, and lignin. The kinetic parameters of the distributed activation energy model indicated that the activation energy distribution for the pseudocomponents follows lignin, cellulose, and hemicellulose in descending order. The activation energy values for each set of reactions are similar between the heating rates, which suggests that it is independent of the heating rate between 10 K/min and 30 K/min. For all the biomass samples, the increased heating rate resulted in the overlap of the hemicellulose and cellulose degradation events.

scholarly journals DTA Evaluation of Spruce Wood Degradation Process

2017 ◽  
Vol 25 (40) ◽  
pp. 41-48
Author(s):  
Ivan Hrušovský ◽  
Peter Rantuch ◽  
Jozef Martinka ◽  
Simona Dzíbelová
Keyword(s):  
Activation Energy ◽  
Room Temperature ◽  
Degradation Process ◽  
Heating Rates ◽  
Wood Degradation ◽  
Wood Sawdust ◽  
Spruce Wood ◽  
Calculated Activation Energy ◽  
Two Stages ◽  
Calculated Activation

Abstract The decomposition stages of spruce wood sawdust were analyzed by means of sequential differential calorimetry. Two stages of decomposition were identified and activation energy of one stage was calculated using the Kissinger method. The DTA was conducted by means of SEDEX safety calorimeter. Sample was analyzed under three heating rates of 10, 20 and 45 °C/h in temperature range from room temperature to 400 °C. The calculated activation energy for the last and most clear decomposition peak was 122.63 KJ/mol. The results are comparable with the data calculated by J.V. Rissanen et al., who calculated activation energy for Spruce hemicellulose as 120 KJ/mol.

Thermogravimetric Analysis of KCl-Pretreated Soybean Stalk

2015 ◽  
Vol 1092-1093 ◽  
pp. 118-121
Author(s):  
Dong Yu Chen ◽  
Qing Yu Liu
Keyword(s):  
Activation Energy ◽  
Thermogravimetric Analysis ◽  
Metal Salts ◽  
Pyrolysis Kinetics ◽  
Ozawa Method ◽  
Heating Rates ◽  
Energy Value ◽  
Lower Activation ◽  
Higher Temperature ◽  
Kinetics Of

To study the influence of KCl pretreating on the pyrolysis kinetics of soybean stalk, the pyrolysis of soybean stalk pretreated by different concentration KCl solutions were performed by nonisothermal thermogravimetric analysis (TGA) at five different heating rates. The Ozawa method was employed to calculate the activation energy. The results showed that the pyrolysis process of the soybean stalk pretreated by 3% and 10% KCl solution can be separated into four stages (water loss, depolymerization and vitrification, thermal decomposition, and carbonization). With the heating rate increasing, the main pyrolysis zone of the TG (thermogravimetric) and DTG curves move to the higher temperature region, and the maximum pyrolysis rate and its corresponding temperature increase too. A small amount of metal salts addition is conducive to the formation of volatile, and a certain amount of metal salts can improve the charcoal yield. More KCl additive makes the lower activation energy value, and the obtained activation energy value increases with the reaction degree.

Study on the thermal degradation of chitosan-Cu/Ni/Mn complexes

e-Polymers ◽  
2012 ◽  
Vol 12 (1) ◽  
Author(s):  
Chun-Yan Ou ◽  
Si-Dong Li
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Thermal Degradation ◽  
Metal Ion ◽  
Main Chain ◽  
Characteristic Temperature ◽  
Ozawa Method ◽  
Heating Rates ◽  
Nickel Ions ◽  
The Impact

AbstractThe thermal degradation of chitosan-Cu/ Ni/ Mn complexes at different heating rates in nitrogen was studied by thermogravimetric analysis (TGA) in the temperature range 30-500 °C. Fourier transform-infrared (FTIR) was utilized to determine the microstructure of chitosan-metal complexes. The results of FTIR show that there are coordinating bonds between chitosan and cupric, manganese, nickel ions. The results of thermal analysis indicate that the thermal degradation of chitosan-Cu/ Mn/Ni complexes is a two-step reaction, which is related to water loss from the material, the deacetylation of the main chain and the cleavage of glycosidic linkages of chitosan, respectively. Characteristic temperature increases with the increment of heating rate and the impact of coordination of metal ion on the thermal degradation of chitosan is very significant. The kinetic parameters were determined by using Flynn-Wall-Ozawa method. The results show that the activation energy of the complexes is different but the variable tendency is similar

Kinetic study of the stabilizing effect of aluminum trihydroxide on thermal degradation of epoxy resin

e-Polymers ◽  
2014 ◽  
Vol 14 (2) ◽  
pp. 133-137 ◽  
Author(s):  
Jiangbo Wang ◽  
Jialin Fang ◽  
Chengwei Wang ◽  
Yongyou Li ◽  
Mengjiao Huang
Keyword(s):  
Activation Energy ◽  
Thermal Degradation ◽  
Epoxy Resin ◽  
Fire Retardant ◽  
Degradation Process ◽  
Ozawa Method ◽  
Degradation Behaviour ◽  
Stabilizing Effect ◽  
Thermal Degradation Process ◽  
Aluminum Trihydroxide

AbstractThe stabilizing effect of epoxy resin (EP)/aluminum trihydroxide (ATH) was measured by thermogravimetric analysis (TGA) in an N2 flow. The Kissinger and Flynn-Wall-Ozawa methods were used to determine the activation energy of non-isothermal degradation at different stages. The results showed that there was a slight increase in activation energy after ATH was added. It confirms the fire-retardant effect of ATH on the thermal degradation behaviour of pure EP. The Flynn-Wall-Ozawa method showed that flame-retardant ATH remarkably enhanced the activation energy of the thermal degradation process for EP, albeit the conversion rate being only 10%, which demonstrated the stabilization of ATH to the char layer of EP.

Comparative study on the pyrolysis kinetics of polyurethane foam from waste refrigerators

2019 ◽  
Vol 38 (3) ◽  
pp. 271-278 ◽  
Author(s):  
Zhitong Yao ◽  
Shaoqi Yu ◽  
Weiping Su ◽  
Weihong Wu ◽  
Junhong Tang ◽  
...  
Keyword(s):  
Activation Energy ◽  
Polyurethane Foam ◽  
Model Fitting ◽  
Energy Model ◽  
Pyrolysis Kinetics ◽  
Ozawa Method ◽  
Heating Rates ◽  
Distributed Activation Energy Model ◽  
Model Free ◽  
Kinetics Of

Thermal treatment offers advantages of significant volume reduction and energy recovery for the polyurethane foam from waste refrigerators. In this work, the pyrolysis kinetics of polyurethane foam was investigated using the model-fitting, model-free and distributed activation energy model methods. The thermogravimetric analysis indicated that the polyurethane foam decomposition could be divided into three stages with temperatures of 38°C–400°C, 400°C–550°C and 550°C–1000°C. Peak temperatures for the major decomposition stage (<400°C) were determined as 324°C, 342°C and 344°C for heating rates of 5, 15 and 25 K min-1, respectively. The activation energy ( Eα) from the Friedman, Flynn–Wall–Ozawa and Tang methods increased with degree of conversion ( α) in the range of 0.05 to 0.5. The coefficients from the Flynn–Wall–Ozawa method were larger and the resulted Eα values fell into the range of 163.980–328.190 kJ mol-1 with an average of 206.099 kJ mol-1. For the Coats–Redfern method, the diffusion models offered higher coefficients, but the E values were smaller than that from the Flynn–Wall–Ozawa method. The Eα values derived from the distributed activation energy model method were determined as 163.536–334.231 kJ mol-1, with an average of 206.799 kJ mol-1. The peak of activation energy distribution curve was located at 205.929 kJ mol-1, consistent with the thermogravimetric results. The Flynn–Wall–Ozawa and distributed activation energy model methods were more reliable for describing the polyurethane foam pyrolysis process.

scholarly journals Oxygen-enriched combustion of lignite

2015 ◽  
Vol 19 (4) ◽  
pp. 1389-1392 ◽  
Author(s):  
Yong-Feng Zhang ◽  
Xiang-Yun Chen ◽  
Qian-Cheng Zhang ◽  
Chun-Ping Li ◽  
Quan Zhou
Keyword(s):  
Activation Energy ◽  
Kinetic Parameter ◽  
Oxygen Concentration ◽  
Combustion Kinetics ◽  
Ozawa Method ◽  
Heating Rates ◽  
Thermogravimetric Analyzer ◽  
Kinetics Of

The study is concerned on the oxygen-enriched combustion kinetics of lignite. Thermogravimetric experiments were carried out in a thermogravimetric analyzer under O2/N2 conditions, and operated at different heating rates ranging from 5?C per minute to 25?C per minute. Flynn-Wall-Ozawa method was used to calculate the kinetic parameter. The value of activation energy increased when the oxygen concentration varied from 21% to 70%.

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).

Sign in / Sign up

Export Citation Format

Share Document