scholarly journals A Case Study of Polyetheretherketone (II): Playing with Oxygen Concentration and Modeling Thermal Decomposition of a High-Performance Material

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1577
Author(s):  
Aditya Ramgobin ◽  
Gaëlle Fontaine ◽  
Serge Bourbigot
Keyword(s):  
Thermal Decomposition ◽  
Kinetic Model ◽  
High Performance ◽  
Chain Scission ◽  
Kinetic Decomposition ◽  
Decomposition Models ◽  
Set Up ◽  
Decomposition Pathway ◽  
Kinetics Of

Kinetic decomposition models for the thermal decomposition of a high-performance polymeric material (polyetheretherketone, PEEK) were determined from specific techniques. Experimental data from thermogravimetric analysis (TGA) and previously elucidated decomposition mechanisms were combined with a numerical simulating tool to establish a comprehensive kinetic model for the decomposition of PEEK under three atmospheres: nitrogen, 2% oxygen, and synthetic air. Multistepped kinetic models with subsequent and competitive reactions were established by taking into consideration the different types of reactions that may occur during the thermal decomposition of the material (chain scission, thermo-oxidation, char formation). The decomposition products and decomposition mechanism of PEEK which were established in our previous report allowed for the elucidation of the kinetic decomposition models. A three-stepped kinetic thermal decomposition pathway was a good fit to model the thermal decomposition of PEEK under nitrogen. The kinetic model involved an autocatalytic type of reaction followed by competitive and successive nth order reactions. Such types of models were set up for the evaluation of the kinetics of the thermal decomposition of PEEK under 2% oxygen and in air, leading to models with satisfactory fidelity.

scholarly journals Degradation Kinetics of Clavulanic Acid in Fermentation Broths at Low Temperatures

Antibiotics ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 6 ◽  
Author(s):  
David Gómez-Ríos ◽  
Howard Ramírez-Malule ◽  
Peter Neubauer ◽  
Stefan Junne ◽  
Rigoberto Ríos-Estepa
Keyword(s):  
Kinetic Model ◽  
Clavulanic Acid ◽  
Low Temperatures ◽  
High Performance ◽  
Degradation Kinetics ◽  
Streptomyces Clavuligerus ◽  
Submerged Cultures ◽  
Fast Decline ◽  
Fermentation Broths ◽  
Kinetics Of

Clavulanic acid (CA) is a β-lactam antibiotic inhibitor of β-lactamase enzymes, which confers resistance to bacteria against several antibiotics. CA is produced in submerged cultures by the filamentous Gram-positive bacterium Streptomyces clavuligerus; yield and downstream process are compromised by a degradation phenomenon, which is not yet completely elucidated. In this contribution, a study of degradation kinetics of CA at low temperatures (−80, −20, 4, and 25 °C) and pH 6.8 in chemically-defined fermentation broths is presented. Samples of CA in the fermentation broths showed a fast decline of concentration during the first 5 h followed by a slower, but stable, reaction rate in the subsequent hours. A reversible-irreversible kinetic model was applied to explain the degradation rate of CA, its dependence on temperature and concentration. Kinetic parameters for the equilibrium and irreversible reactions were calculated and the proposed kinetic model was validated with experimental data of CA degradation ranging 16.3 mg/L to 127.0 mg/L. Degradation of the chromophore CA-imidazole, which is commonly used for quantifications by High Performance Liquid Chromatography, was also studied at 4 °C and 25 °C, showing a rapid rate of degradation according to irreversible first-order kinetics. A hydrolysis reaction mechanism is proposed as the cause of CA-imidazole loss in aqueous solutions.

Recent Advances in the Thermal Decomposition of Cyclic Nitramines

1992 ◽  
Vol 296 ◽  
Author(s):  
Richard Behrens ◽  
Suryanarayana Bulusu
Keyword(s):  
Thermal Decomposition ◽  
Liquid Phase ◽  
Molecular Conformation ◽  
Reaction Pathways ◽  
Thermally Stable ◽  
Decomposition Products ◽  
Stable Product ◽  
Cyclic Nitramines ◽  
Decomposition Pathway ◽  
Kinetics Of

AbstractThe effects of physical properties and molecular conformation on the thermal decomposition kinetics of several cyclic nitramines are examined and compared to the decomposition of RDX. The compounds used in the study are: octahydro-1,3,5,7-tetranitro- 1,3,5,7-tetrazocine (HMX), hexahydro-l-nitroso-3,5-dinitro-s-triazine (ONDNTA), 1,3,5- trinitro- 1,3,5-triazacycloheptane (TNCHP), and 2-oxo-1,3,5-trinitro-1,3,5-triazacyclohexane (K6). The decomposition pathways of HMX in the liquid phase are similar to the four parallel decomposition pathways that control the decomposition of RDX in the liquid phase. The products formed during the thermal decomposition of ONDNTA arise from multiple reaction pathways. The identities and temporal behaviors of the ONDNTA decomposition products are discussed. TNCHP is thermally stable in the liquid phase. The decomposition products from TNCHP are formed via multiple reaction pathways. One decomposition pathway for TNCHP is through its mononitroso intermediate. TNCHP does not form a stable product that is analogous to oxy-s-triazine (OST) formed in RDX or the smaller ring fragments formed in the liquid-phase decomposition of HMX. K6 is less thermally stable and the decomposition mechanism is much simpler than that of RDX, HMX and TNCHP. The thermal decomposition of K6 occurs between 150 and 180 °C. The products formed during the decomposition of K6 are mainly CH2O and N2O with minor amounts or HCN, CO, NO, and NO2.

Comparison of Thermal Decomposition Kinetics of Magnesite and Limestone

2013 ◽  
Vol 652-654 ◽  
pp. 2580-2583 ◽  
Author(s):  
Lei Su ◽  
Gang Zhang ◽  
Yu Dong ◽  
Jian Feng ◽  
Dong Liu
Keyword(s):  
Thermal Decomposition ◽  
Alkaline Earth ◽  
Earth Metal ◽  
Decomposition Kinetics ◽  
Thermal Decomposition Kinetics ◽  
Analysis Method ◽  
Metal Carbonates ◽  
Thermogravimetric Data ◽  
Kinetic Decomposition ◽  
Kinetics Of

The thermal decomposition kinetics of magnesite and limestone, which are alkaline earth metal carbonates, were investigated using thermal analysis method. The research results showed that their kinetic decomposition characteristics and apparent decomposition activation energy have the comparability. Based on the thermodynamic/thermogravimetric data, the industrial production process of magnesite and limestone can draw on the experience of each other because of their similar decomposition thermodynamics and kinetics.

scholarly journals Effects of dopants on the isothermal decomposition kinetics of potassium metaperiodate

2011 ◽  
Vol 76 (8) ◽  
pp. 1129-1138
Author(s):  
Karuvanthodi Muraleedharan ◽  
Parambil Kannan ◽  
Ganga Devi
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Kinetic Model ◽  
Entire Range ◽  
Decomposition Kinetics ◽  
Isothermal Decomposition ◽  
Acceleration Period ◽  
Two Stages ◽  
Kinetics Of

The isothermal decomposition and kinetics of potassium metaperiodate (KIO4) were studied by thermogravimetry as a function of the concentration of dopants. The thermal decomposition of KIO4 proceeds mainly through two stages: an acceleration period up to ? = 0.50 and a decay stage. The thermal decomposition data for both doped and untreated KIO4 were found to be best described by the Prout-Tompkins Equation. The ? - t data of doped and untreated samples of KIO4 were subjected to isoconversional studies for the determination of the activation energy values. The isoconversional studies of the isothermal decomposition of untreated and doped samples of KIO4 indicated that the thermal decomposition of KIO4 proceeds through a single kinetic model, the Prout-Tompkins model, throughout the entire range of conversion, as opposed to earlier observations.

Cure Kinetics of High Performance Epoxy Molding Compounds

2014 ◽  
Vol 1024 ◽  
pp. 151-154
Author(s):  
Chean Cheng Su ◽  
Cheng Fu Yang ◽  
Chien Huan Wei
Keyword(s):  
Kinetic Model ◽  
High Performance ◽  
Resin Transfer Molding ◽  
Cure Kinetics ◽  
Molding Process ◽  
Transfer Molding ◽  
Molding Compounds ◽  
Higher Temperature ◽  
Kinetics Of ◽  
Rubber State

The reaction of EMCs with the triphenylphosphine-1,4-benzoquinone (TPP-BQ) latent catalyst also had a higher temperature sensitivity compared to the reaction of EMCs with triphenylphosphine (TPP) catalyst. In resin transfer molding, EMCs containing the TPP-BQ thermal latency accelerator are least active at a low temperature. Consequently, EMCs have a low melt viscosity before gelation, and the resins and filler are evenly mixed in the kneading process. Additionally, the rheological property, flowability, is increased before the EMC form a network structure in the molding process. The proposed kinetic model adequately describes curing behavior in EMCs cured with two different organophosphine catalysts up to the rubber state in the progress of curing.

Continuous Quantitative Monitoring of Mural, Platelet-Dependent, Thrombus Kinetics in the Crushed Rat Femoral Vein

1991 ◽  
Vol 65 (04) ◽  
pp. 425-431 ◽  
Author(s):  
F Stockmans ◽  
H Deckmyn ◽  
J Gruwez ◽  
J Vermylen ◽  
R Acland
Keyword(s):  
Thrombus Formation ◽  
Femoral Vein ◽  
Maximum Size ◽  
Digital Analysis ◽  
Video Recordings ◽  
Quantitative Monitoring ◽  
Set Up ◽  
Kinetics Of ◽  
Quantitative Nature

SummaryA new in vivo method to study the size and dynamics of a growing mural thrombus was set up in the rat femoral vein. The method uses a standardized crush injury to induce a thrombus, and a newly developed transilluminator combined with digital analysis of video recordings. Thrombi in this model formed rapidly, reaching a maximum size 391 ± 35 sec following injury, after which they degraded with a half-life of 197 ± 31 sec. Histological examination indicated that the thrombi consisted mainly of platelets. The quantitative nature of the transillumination technique was demonstrated by simultaneous measurement of the incorporation of 111In labeled platelets into the thrombus. Thrombus formation, studied at 30 min interval in both femoral veins, showed satisfactory reproducibility overall and within a given animalWith this method we were able to induce a thrombus using a clinically relevant injury and to monitor continuously and reproducibly the kinetics of thrombus formation in a vessel of clinically and surgically relevant size

Kinetics of Thermal Decomposition of Lime Stone

1967 ◽  
Vol 53 (7) ◽  
pp. 740-743 ◽  
Author(s):  
Kiyoshi SAWAMURA ◽  
Kazuichi MIZOGUCHI ◽  
Tetsuro HANADA ◽  
Kunihiko MAKINO
Keyword(s):  
Thermal Decomposition ◽  
Kinetics Of Thermal Decomposition ◽  
Kinetics Of ◽  
Lime Stone

Thermal Decomposition Kinetics of Torrefied Oil Palm Empty Fruit Bunch Briquettes

2016 ◽  
Vol 10 (3) ◽  
pp. 325-328 ◽  
Author(s):  
Bemgba Nyakuma ◽  
◽  
Arshad Ahmad ◽  
Anwar Johari ◽  
Tuan Abdullah ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Oil Palm ◽  
Decomposition Kinetics ◽  
Thermal Decomposition Kinetics ◽  
Kinetic Properties ◽  
Tg Analysis ◽  
Empty Fruit Bunches ◽  
Thermal Lag ◽  
Profile Characteristics ◽  
Kinetics Of

The study is aimed at investigating the thermal behavior and decomposition kinetics of torrefied oil palm empty fruit bunches (OPEFB) briquettes using a thermogravimetric (TG) analysis and the Coats-Redfern model. The results revealed that thermal decomposition kinetics of OPEFB and torrefied OPEFB briquettes is significantly influenced by the severity of torrefaction temperature. Furthermore, the temperature profile characteristics; Tonset, Tpeak, and Tend increased consistently due to the thermal lag observed during TG analysis. In addition, the torrefied OPEFB briquettes were observed to possess superior thermal and kinetic properties over the untorrefied OPEFB briquettes. It can be inferred that torrefaction improves the fuel properties of pelletized OPEFB for potential utilization in bioenergy conversion systems.

Thermal Decomposition Kinetics of Glyphosate (GP) and its Metabolite Aminomethylphosphonic Acid (AMPA)

2019 ◽  
Author(s):  
Milad Narimani ◽  
Gabriel da Silva
Keyword(s):  
Thermal Decomposition ◽  
Reaction Rate ◽  
Decomposition Kinetics ◽  
Rate Theory ◽  
Thermal Decomposition Mechanism ◽  
Treatment Processes ◽  
Aminomethylphosphonic Acid ◽  
Reaction Rate Theory ◽  
Decomposition Chemistry ◽  
Kinetics Of

Glyphosate (GP) is a widely used herbicide worldwide, yet accumulation of GP and its main byproduct, aminomethylphosphonic acid (AMPA), in soil and water has raised concerns about its potential effects to human health. Thermal treatment processes are one option for decontaminating material containing GP and AMPA, yet the thermal decomposition chemistry of these compounds remains poorly understood. Here, we have revealed the thermal decomposition mechanism of GP and AMPA by applying computational chemistry and reaction rate theory methods. <br>

Sign in / Sign up

Export Citation Format

Share Document