scholarly journals Enthalpy-Entropy Compensation in Polyester Degradation Reactions

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Adam Al-Mulla
Keyword(s):  
Compensation Effect ◽  
Degradation Kinetics ◽  
Isokinetic Temperature ◽  
Heating Rates ◽  
Polybutylene Terephthalate ◽  
Degradation Reactions ◽  
Zone Ii ◽  
Polyester Degradation ◽  
Kinetics Of ◽  
Nonisothermal Conditions

In an earlier work the author had studied the degradation kinetics of polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), and polybutylene terephthalate (PBT) under nonisothermal conditions in air and N2at heating rates of 5, 10, 15, and 20°C/min. In this paper the kinetic degradation parameters of PET, PTT, and PBT were estimated using the Coats-Redfern method for two different weight loss regions ranging from 2–8% (Zone I) and 8–40% (Zone II). A comparative analysis of the enthalpy-entropy compensation effect for these polyesters in air and N2is presented. A linear relationship was found to exist between entropy and enthalpy values. The following criteria were applied to establish an enthalpy-entropy compensation effect and to check the presence of an isokinetic temperature: (a) Exner’s plot of logk3T1versus logk3T2, and (b) Krug et al. linear regression of ΔHversus ΔG.By the use of the latter two methods, varying isokinetic temperatures were obtained. These temperatures were not in the range of the experimental work conducted, indicating that these systems do not display compensation phenomena.

Characterization and thermal degradation kinetics of thermoplastic polyimide based on BAPP

2017 ◽  
Vol 30 (7) ◽  
pp. 787-793 ◽  
Author(s):  
Xu Su ◽  
Yong Xu ◽  
Linshuang Li ◽  
Chaoran Song
Keyword(s):  
Thermogravimetric Analysis ◽  
Thermal Degradation ◽  
Degradation Kinetics ◽  
Degradation Process ◽  
Thermal Degradation Kinetics ◽  
Heating Rates ◽  
Step Method ◽  
Nitrogen Derivative ◽  
Degradation Reaction ◽  
Kinetics Of

Two kinds of thermoplastic polyimides (PIs) were synthesized via a two-step method with 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP), 4,4′-oxydianiline (ODA) diamine, and 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), and their thermal degradation kinetics was studied by thermogravimetric analysis at different heating rates under nitrogen. Derivative thermogravimetric analysis curves indicated a simple, single-stage degradation process in PI BTDA-BAPP and a two-stage degradation process in PI BTDA-ODA-BAPP. The activation energies ( Eas) of the thermal degradation reaction were determined by the Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose methods without a knowledge of the kinetic reaction mechanism. By comparing the values of Ea and weight loss temperatures, it was demonstrated that the thermal stability of PI BTDA-ODA-BAPP was superior to that of PI BTDA-BAPP.

Thermal Decomposition Kinetics of Flame Retardant Polybutylene Terephthalate Matrix Composites

2019 ◽  
Vol 956 ◽  
pp. 181-191
Author(s):  
Jian Lin Xu ◽  
Bing Xue Ma ◽  
Cheng Hu Kang ◽  
Cheng Cheng Xu ◽  
Zhou Chen ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Flame Retardant ◽  
Mass Loss Rate ◽  
Decomposition Reaction ◽  
Decomposition Kinetics ◽  
Thermal Decomposition Kinetics ◽  
Heating Rates ◽  
Polybutylene Terephthalate ◽  
Kinetics Of

The thermal decomposition kinetics of polybutylene terephthalate (PBT) and flame-retardant PBT (FR-PBT) were investigated by thermogravimetric analysis at various heating rates. The kinetic parameters were determined by using Kissinger, Flynn-Wall-Ozawa and Friedman methods. The y (α) and z (α) master plots were used to identify the thermal decomposition model. The results show that the rate of residual carbon of FR-PBT is higher than that of PBT and the maximum mass loss rate of FR-PBT is lower than that of PBT. The values of activation energy of PBT (208.71 kJ/mol) and FR-PBT (244.78 kJ/mol) calculated by Kissinger method were higher than those of PBT (PBT: 195.54 kJ/mol) and FR-PBT (FR-PBT: 196.00 kJ/mol) calculated by Flynn-Wall-Ozawa method and those of PBT and FR-PBT (PBT: 199.10 kJ/mol, FR-PBT: 206.03 kJ/mol) calculated by Friedman methods. There is a common thing that the values of activation energy of FR-PBT are higher than that of PBT in different methods. The thermal decomposition reaction models of the PBT and FR-PBT can be described by Avarami-Erofeyev model (A1).

Pyrolysis kinetics of recycled polyesters

2015 ◽  
Vol 27 (4) ◽  
pp. 523-531 ◽  
Author(s):  
Jaber Al-Juaidiyah
Keyword(s):  
Textile Industry ◽  
Degradation Kinetics ◽  
Nitrogen Atmosphere ◽  
Coefficient Of Determination ◽  
Pyrolysis Kinetics ◽  
Polybutylene Terephthalate ◽  
Exponential Factor ◽  
Content Type ◽  
Kissinger Model ◽  
Kinetics Of

Purpose – The purpose of this paper is to study the non-isothermal degradation kinetics of recycled polybutylene terephthalate, polytrimethylene terephthalate and polyethylene terephthalate using thermogravimetric analysis (TGA) in a nitrogen atmosphere. Design/methodology/approach – To achieve this goal, the author utilized standard kinetic models, such as Coats-Redfern and Kissinger equations, for analysis of the TGA data. Findings – When applied to the TGA data, the Kissinger model resulted in a coefficient of determination (R2) value greater than 0.99. Originality/value – This study describes the maiden application of the Kissinger model to obtain the pre-exponential factor (A) and activation energy (E) for different polyester systems used in the textile industry.

scholarly journals The novel modeling approach for the study of thermal degradation of PMMA/nanooxide systems

2019 ◽  
Vol 38 (1) ◽  
pp. 95
Author(s):  
Mirjana Jovicic ◽  
Oskar Bera ◽  
Katalin Meszaros Szecsenyi ◽  
Predrag Kojic ◽  
Jaroslava Budinski-Simendic ◽  
...  
Keyword(s):  
Thermal Degradation ◽  
Degradation Kinetics ◽  
The Novel ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Total Mass Loss ◽  
Thermal Changes ◽  
Silica Alumina ◽  
Individual Contributions ◽  
Kinetics Of

PMMA (poly(methyl methacrylate)) nanocomposites differing in their nature, size, and surface area were prepared containing one volume percent of silica, alumina or titania. These samples and pure PMMA were prepared in order to analyze how the presence of nanooxides affects the thermal stability and degradation kinetics of the materials. A detailed study of thermal degradation and thermal changes was performed by Simultaneous Thermogravimetry and Differential Scanning Calorimetry (SDT). The proposed mathematical model, including all three heating rates in one minimizing function, well fitted all TGA data obtained with a very high coefficient of correlation. This enabled an assessment of four decomposition steps of the PMMA samples and a calculation of their activation energies and individual contributions to total mass loss. The addition of the largest nanoparticles (titania) caused the highest activation energy for each DTG stage of the PMMA/nanooxide systems. The enhancement of head-to-head H–H bonding strength was achieved by addition of alumina and titania. The influence of the size and nature of nanoparticles on the glass transition temperature of prepared PMMA systems was also determined.

Effect of Pd Nanoparticle on the Thermal Degradation Kinetics of Nylon 6/Pd Nanocomposite Prepared by a Dry Process

2012 ◽  
Vol 486 ◽  
pp. 27-33 ◽  
Author(s):  
Jae Young Lee ◽  
Sung Wan Hong ◽  
Kyeong Sik Han ◽  
Taeck Hong Lee ◽  
Hong Ki Lee
Keyword(s):  
Activation Energy ◽  
Thermal Degradation ◽  
Degradation Kinetics ◽  
Pd Nanoparticles ◽  
Nylon 6 ◽  
Thermal Degradation Kinetics ◽  
Heating Rates ◽  
Dry Process ◽  
Effect Of Pd ◽  
Kinetics Of

Palladium (Pd) nanoparticles were incorporated into a nylon 6 film via a dry process which consisted of simultaneous vaporization, penetration and reduction processes of palladium (II) bis (acetylacetonate, Pd (acac)2) at 180°C for various exposure time. The even dispersion of the generated Pd nanoparticles were observed by transmission electron microscope (TEM) and the Pd loading weight of about 15~43 wt% was measured by thermogravimetric analysis (TGA). In order to study the catalytic effect of Pd nanoparticles on the thermal degradation kinetics of nylon 6, TGA data at various heating rates were introduced to Flynn & Wall equation. The thermal degradation activation energy for neat nylon 6 was ca. 162~178 kJ/mol over the thermal degradation fraction of 0.05~0.40 while that of the nylon 6/Pd (26.5 wt%) nanocomposite was ca. 110~169 kJ/mol over the same fraction range. It meant the Pd nanoparticles were acted as a catalyst on the depolymerization of amide group in nylon 6. It was also found that the activation energy decreased slightly with the increasing Pd loading weight.

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.

scholarly journals Fabrication and Thermal Degradation Kinetics of PBT/BEO/Nano-Sb2O3 Composites

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Meng Ma ◽  
Lei Niu ◽  
Jinming Ma ◽  
Jiqiang Ma ◽  
Tifeng Jiao
Keyword(s):  
Thermal Stability ◽  
Thermal Degradation ◽  
Flame Retardant ◽  
Heating Rate ◽  
Thermal Hysteresis ◽  
Degradation Kinetics ◽  
Thermal Degradation Kinetics ◽  
Polybutylene Terephthalate ◽  
Blending Method ◽  
Kinetics Of

Developing polybutylene terephthalate (PBT) with high thermal stability and flame-retardant properties is crucial for automotive, biomedical devices, electronics, and other fields. Herein, we focus on a PBT/brominated epoxy resin (BEO)/nano-Sb2O3 composites by a melt-blending method. The effects of heating rate and nano-Sb2O3 content on the thermal stability and thermal degradation kinetics of PBT composites were studied by TG-DSC. With the increasing of heating rate, the thermal hysteresis effect of temperature gradient is produced, which is eliminated when the temperature exceeds 400°C. With the increase of nano-Sb2O3 content, the E a of PBT/BEO/nano-Sb2O3 composites increases at first and then decreases. When the content of nano-Sb2O3 is 3 wt%, the E a of PBT/BEO/nano-Sb2O3 is the highest, which is 66.18 kJ/mol (31.43%) higher than that of neat PBT. Also, the exploration of the thermal degradation kinetics of PBT/BEO/nano-Sb2O3 composites is expected to provide research ideas for new high flame-retardant materials.

Kinetics of aquation of bromopentaamminechromium(III) and bromopentaamminecobalt(III) ions in water-alcohol solvents

1979 ◽  
Vol 44 (2) ◽  
pp. 495-501 ◽  
Author(s):  
Vladislav Holba ◽  
Oľga Grančičová
Keyword(s):  
Reaction Kinetics ◽  
Rate Constants ◽  
Compensation Effect ◽  
Activation Parameters ◽  
Butyl Alcohol ◽  
Isokinetic Temperature ◽  
Tert Butyl Alcohol ◽  
Alcohol Solvents ◽  
Kinetics Of ◽  
Water Alcohol

The rate constants and activation parameters of aquation of bromopentaamminechromium(III) and bromopentaamminecobalt(III) ions were determined in mixtures of water with methanol, ethanol, 2-propanol, and tert-butyl alcohol. A compensation effect was observed in the first three mixtures and the isokinetic temperature was determined. The rate constant were correlated with the ionizing strength of the solvent. The influence of interactions between the water and alcohol molecules on the reaction kinetics is discussed.

scholarly journals Rheological and thermal degradation properties of hyperbranched polyisoprene prepared by anionic polymerization

2019 ◽  
Vol 6 (11) ◽  
pp. 190869 ◽  
Author(s):  
Shehu Habibu ◽  
Norazilawati Muhamad Sarih ◽  
Nor Asrina Sairi ◽  
Muzafar Zulkifli
Keyword(s):  
Thermal Degradation ◽  
Degradation Kinetics ◽  
Diffusion Mechanism ◽  
High Vacuum ◽  
Linear Polymer ◽  
Branched Polymers ◽  
Size Exclusion ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Kinetics Of

Hyperbranched polyisoprene was prepared by anionic copolymerization under high vacuum condition. Size exclusion chromatography was used to characterize the molecular weight and branching nature of these polymers. The characterization by differential scanning calorimetry and melt rheology indicated lower T g and complex viscosity in the branched polymers as compared with the linear polymer. Degradation kinetics of these polymers was explored using thermogravimetric analysis via non-isothermal techniques. The polymers were heated under nitrogen from ambient temperature to 600°C using heating rates from 2 to 15°C min −1 . Three kinetics methods namely Friedman, Flynn–Wall–Ozawa and Kissinger–Akahira–Sunose were used to evaluate the dependence of activation energy ( E a ) on conversion ( α ). The hyperbranched polyisoprene decomposed via multistep mechanism as manifested by the nonlinear relationship between α and E a while the linear polymer exhibited a decline in E a at higher conversions. The average E a values range from 258 to 330 kJ mol −1 for the linear, and from 260 to 320 kJ mol −1 for the branched polymers. The thermal degradation of the polymers studied involved one-dimensional diffusion mechanism as determined by Coats–Redfern method. This study may help in understanding the effect of branching on the rheological and decomposition kinetics of polyisoprene.

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