Thermal Degradation of Ionic Liquids at Elevated Temperatures

2004 ◽  
Vol 57 (2) ◽  
pp. 145 ◽  
Author(s):  
Krisztian J. Baranyai ◽  
Glen B. Deacon ◽  
Douglas R. MacFarlane ◽  
Jennifer M. Pringle ◽  
Janet L. Scott
Keyword(s):  
Thermal Stability ◽  
Ionic Liquids ◽  
Thermal Degradation ◽  
Elevated Temperatures ◽  
Degradation Products ◽  
Operating Temperature ◽  
Imidazolium Cation

Ionic liquids based on the imidazolium cation are found to degrade, yielding volatile degradation products, at temperatures significantly lower than previously reported and thus a parameter Tz/x (the maximum operating temperature) is developed to provide a more appropriate estimate of thermal stability.

Thermal degradation of EDTA chelates in aqueous solution

1982 ◽  
Vol 60 (10) ◽  
pp. 1207-1213 ◽  
Author(s):  
Ramunas J. Motekaitis ◽  
X. B. Cox III ◽  
Patrick Taylor ◽  
Arthur E. Martell ◽  
Brad Miles ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Thermal Degradation ◽  
Elevated Temperatures ◽  
Degradation Products ◽  
Iminodiacetic Acid ◽  
Reaction Products ◽  
Degradation Rates ◽  
Lower Temperature Range ◽  
Higher Temperature ◽  
Lower Temperature

The thermal degradation of Ca(II), Mg(II), Zn(II), Fe(II), and Ni(II) chelates of EDTA was investigated in alkaline aqueous solution at elevated temperatures (230–310 °C). The kinetics of decomposition were followed by nmr, titrimetry, and spectrophotometry. Reaction products were identified through nmr and by gas chromatography. The relative order of degradation rates, as measured by the loss of EDTA, was found to be Mg(II) > Ca(II) > Zn(II) > Fe(II) > Ni(II). The main degradation products formed in the lower temperature range (~250 °C) are iminodiacetic acid, hydroxyethyliminodiacetic acid, and ethylene glycol. Higher temperature products are primarily dimethylamine and carbon dioxide. The rates of degradation of Ca(II), Mg(II), and Zn(II) EDTA chelates are considerably enhanced when either phosphate is present or a glass-lined autoclave is employed.

Thermal aging of 1-alkyl-3-methylimidazolium ionic liquids and its effect on dissolved cellulose

Holzforschung ◽  
2010 ◽  
Vol 64 (2) ◽  
Author(s):  
Falk Liebner ◽  
Ilabahen Patel ◽  
Gerald Ebner ◽  
Ernst Becker ◽  
Michael Horix ◽  
...  
Keyword(s):  
Ionic Liquids ◽  
Thermal Degradation ◽  
Thermal Aging ◽  
Degradation Products ◽  
Side Reaction ◽  
Methylene Bridge ◽  
Imidazolium Cations ◽  
Thermal Degradation Products ◽  
Methylene Group ◽  
Cellulose Solvents

Abstract The thermal degradation products of 1-alkyl-3-methyl-imidazolium-type ionic liquids (e.g., BMIM, EMIM), which are commonly used in cellulose chemistry, were identified. Imidazole (5), N-methylimidazole (6), and N-alkylimidazoles (7, 8) are the main products. Moreover, dimeric substituted imidazoles (9–11) were found carrying a methylene bridge formed from the N-methyl structure. The former 1-alkyl group (butyl or ethyl) was not present in any of the dimeric compounds. The N-methylene intermediate (12) acts as a precursor for the substituted imidazoles linked by a methylene group. All thermal degradation products are bases and catalyze the previously described reaction between the reducing end of celluloses and 1-alkyl-3-imidazolium cations. To minimize this side reaction, ionic liquids have to be liberated from such basic compounds prior to application as cellulose solvents. In this regard, the usage of “recycled” (and unpurified) ionic liquids has to be treated with caution.

scholarly journals “Thermal Peroxidation” of Dietary Pentapeptides Yields N-Terminal 1,2-Dicarbonyls

2021 ◽  
Vol 8 ◽  
Author(s):  
Maria Bikaki ◽  
Nikolai Kuhnert
Keyword(s):  
Lipid Peroxidation ◽  
Reaction Mechanism ◽  
Thermal Degradation ◽  
Primary Amine ◽  
Elevated Temperatures ◽  
Degradation Products ◽  
Degradation Mechanism ◽  
Reaction Products ◽  
Unsaturated Lipids

In this contribution we investigate the thermal degradation of dietary-relevant pentapeptides. Most unsaturated lipids degrade by the well-known peroxidation mechanism. Here we show a degradation mechanism of peptides analogous to lipid peroxidation, forming a series of novel degradation products with possible toxicological relevance. At elevated temperatures above 180°C, pentapeptides with an N-terminal phenylalanine moiety react via a debenzylation to form 1,2-dicabonyl compounds, replacing the N-terminal primary amine. We propose a radical-based reaction mechanism that leads via a common peroxoaminal intermediate to two distinct types of reaction products with a terminal α-1,2 diamide or an α-amide-aldehyde functionality.

Bis(isomaleimide) and diphenol blends: Non-isothermal degradation kinetics and TG-FTIR studies

2018 ◽  
Vol 51 (7-8) ◽  
pp. 644-668
Author(s):  
V Sarannya ◽  
S Shamim Rishwana ◽  
R Mahalakshmy ◽  
A Mahendran ◽  
CT Vijayakumar
Keyword(s):  
Thermal Stability ◽  
Thermal Degradation ◽  
Degradation Products ◽  
Degradation Kinetics ◽  
Thermal Polymerization ◽  
Molar Ratio ◽  
Exponential Factor ◽  
Ftir Studies ◽  
D Values ◽  
Thermal Stability Of

Blends of 4,4′-bisisomaleimidodiphenyl methane (VS) with structurally different diphenols are made in 1:1 molar ratio and thermally polymerized. Thermogravimetric studies of the cured materials show that the thermal stability, the degradation pattern and the char yield are much dependent on the structure of the diphenol that is used for blending. The decreased thermal stability of materials from the blends is attributed to decreased cross links owing to the opening of the isomaleimide rings by diphenols during thermal polymerization. The materials with trimethylphenylindane and tetramethylspirobiindane units exhibit char residue of 21% at 800°C. This is due to the thermal stability of the indane and spirobiindane moieties present in the diphenol molecules. The apparent activation energy for thermal degradation ( Ea-D) and pre-exponential factor (ln A) are derived. The Friedman, corrected Flynn–Wall–Ozawa, corrected Kissinger–Akahira–Sunose and advanced Vyazovkin methods are used to calculate the Ea-D values for various reaction extents ( αs). The Ea-D values of poly(4,4′-bisisomaleimido-diphenyl methane) vary from 168 to 226 kJ mol−1. A slight decrease in Ea-D is noted for the initial α levels and increases constantly up to α = 0.3–0.75 and then the Ea-D values decrease with increasing α values. The highest values of Ea-D and ln A are observed for the polymer derived from the blend of VS with tetramethylspirobiindane diphenol. The volatile products obtained during the thermal degradation of these polymers are analysed using thermogravimetry–Fourier transform infrared (TG-FTIR) spectroscopy. The TG-FTIR studies showed the compounds carbon monoxide, carbon dioxide and aromatic amines are the major degradation products from the polymerized blends.

scholarly journals Supramolecular structure and thermal stability of polyamide composite fi lms containing polyfl uorinated alcohol

2019 ◽  
pp. 44-46
Author(s):  
S. V. Kudashev ◽  
V. M. Shapovalov ◽  
A. M. Valenkov ◽  
I. M. Gres ◽  
M. V. Odintsovа ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Thermal Degradation ◽  
Mass Spectroscopy ◽  
Supramolecular Structure ◽  
Elevated Temperatures ◽  
High Thermal Stability ◽  
Carbon Oxides ◽  
Gaseous Products ◽  
Thermal Stability Of ◽  
Montmorillonite Nanoclay

The infl uence of 1,1,9-trihydroperfl uorononanol-1 immobilized on montmorillonite nanoclay, supramolecular structure polycaproamide fi lms and their stability at elevated temperatures. The gaseous products of thermal degradation of polyamide fi lms, including carbon oxides, water, ε-caprolactam, aldehydes and methanol, have been studied by FTIR and mass spectroscopy. The method of thermogravimetry shows that the fl uorine-containing polyamide has a high thermal stability.

scholarly journals Application of pyrolysis-capillary gas chromatography with NPD detection in thermal degradation of polyphosphazenes study

2007 ◽  
Vol 5 (1) ◽  
pp. 271-290 ◽  
Author(s):  
Jürgen Paulsdorf ◽  
Hans-Dieter Wiemhöfer ◽  
Andrej Orinák ◽  
Petr Zámostný ◽  
Zdeněk Bělohlav ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Gas Chromatography ◽  
Thermal Degradation ◽  
Capillary Gas Chromatography ◽  
Degradation Products ◽  
Temperature Stability ◽  
High Temperature Stability ◽  
Flame Resistance ◽  
Conversion Rates

AbstractPolyphosphazenes represent a unique class of polymers with a backbone composed of alternating phosphorous and nitrogen atoms. The thermal behaviour and decomposition of a variety of polyphosphazenes depends on the type of side groups present. Especially those that bear aryloxy side groups, possess a high temperature stability as well as excellent flame resistance. Pyrolysis-capillary gas chromatography has been used in a study of three polyphosphazene samples for thermal stability characterisation. Degradation products were detected with three single detectors for flame ionisation (FID), nitrogen-phosphorous sensitivity (NPD) and mass spectrometry (MSD) at different pyrolysis temperatures ranging from 300°C up to 800°C. The NPD responses for phosphorous or nitrogen fragments of polyphosphazenes have been used for the construction of degradation product schemes and the examination of the thermal stability of the polyphosphazene’s backbone. Partial identification of the degradation products present in the gaseous phase was achieved by MSD. The polyphosphazenes thermal degradation conversion rates were at a maximum at 450–500°C. At various pyrolysis temperatures, the calculated N/P peak area ratio is a function of the degree of polyphosphazene-N=P-chain degradation, and reflective of the nitrogen — phosphorous detector sensitivity. NPD proved to be suitable tool for characterization of polyphospazene thermal stability.

Dielectric Breakdown in Printed Circuit Boards at Elevated Temperatures

1996 ◽  
Author(s):  
P. Singh ◽  
G.T. Galyon ◽  
J. Obrzut ◽  
W.A. Alpaugh
Keyword(s):  
Experimental Data ◽  
Thermal Degradation ◽  
Printed Circuit Boards ◽  
Printed Circuit Board ◽  
Elevated Temperatures ◽  
Dielectric Breakdown ◽  
Circuit Board ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Data Matching

Abstract A time delayed dielectric breakdown in printed circuit boards, operating at temperatures below the epoxy resin insulation thermo-electrical limits, is reported. The safe temperature-voltage operating regime was estimated and related to the glass-rubber transition (To) of printed circuit board dielectric. The TG was measured using DSC and compared with that determined from electrical conductivity of the laminate in the glassy and rubbery state. A failure model was developed and fitted to the experimental data matching a localized thermal degradation of the dielectric and time dependency. The model is based on localized heating of an insulation resistance defect that under certain voltage bias can exceed the TG, thus, initiating thermal degradation of the resin. The model agrees well with the experimental data and indicates that the failure rate and truncation time beyond which the probability of failure becomes insignificant, decreases with increasing glass-rubber transition temperature.

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