Thermal oxidative degradation reactions of perfluoroalkylethers



Publisher: The Administration, Publisher: For sale by the National Technical Information Service in [Washington, D.C.], [Springfield, Va

Written in English
Published: Downloads: 414
Share This

Subjects:

  • Metals -- Anodic oxidation.,
  • Corrosion and anti-corrosives.

Edition Notes

Statementprepared by K.L. Paciorek ... [et al.] ; prepared for National Aeronautics and Space Administration.
SeriesNASA CR -- 168224., NASA contractor report -- NASA CR-168224.
ContributionsPaciorek, K. L., United States. National Aeronautics and Space Administration., Ultrasystems, inc.
The Physical Object
FormatMicroform
Pagination1 v.
ID Numbers
Open LibraryOL15312007M

Thermal degradation usually implies chemical reactions associated with polymer chain scission as a result of temperature or diffusion of small molecules (e.g., O2). Degradation of composite-matrix polymers will more likely be due to thermal instability and the accelerating effects of oxidative attack.   Get Book. One of the most important factors of good health is how our body manages oxidative stress. This is a natural process that occurs at the cellular level. When energy is created in the cell, waste products called free radicals are generated. Free radicals also result from stress and exposure to environmental toxins such as cigarette.   Thermal oxidation Most polymers are subject to oxidation, and it is the most common form of plastic degradation (consider Table 2). Oxidation is a chemical reaction in which oxygen is introduced into the molecular structure of the polymer, creating a form of carbon-oxygen bonds known as carbonyl functionality.   The two major differences are the contributory factors and the by products that are produced. For oxidation, both oxygen and temperature are critical to the degradation of the lubricant however, in thermal degradation, the temperature of the lubricant exceeds its thermal stability (usually in excess of °C). Oxidation usually occurs through the release of free radicals which deplete the.

2 days ago  Extruded polystyrene (XPS) is a thermal insulation material extensively applied in building systems. It has attracted much attention because of outstanding thermal insulation performance, obvious flammability shortcoming and potential energy utilization. To establish the reaction mechanism of XPS’s pyrolysis, thermogravimetric experiments were performed at different heating rates in nitrogen.   Nanotubes made of boron nitride (BN) and carbon have attracted considerable attention within the literature due to their unique mechanical, electrical and thermal properties. In this work, BN and carbon nanotubes, exhibiting high purity (>99%) and similar surface areas (~ m2/g), were systematically investigated for their thermal stability and oxidation behavior by combining thermal. A definition of Oxidation as it applies to lubricants, results and tests to determine oxidation.

Thermal oxidative degradation reactions of perfluoroalkylethers Download PDF EPUB FB2

4 September under Contract NAS, "Thermal Oxidative Degradation Reactions of Peffluoroalkylethers". The investigations were carried out by T. Ito, R. Kratzer, and K. Paciorek, project manager, at the Chemicals and Materials Research Department, Irvine, California.

The contract was administered by the NASA Lewis Research Center. Get this from a library. Thermal oxidative degradation reactions of perfluoroalkylethers. [K L Paciorek; United States. National Aeronautics and Space Administration.; Ultrasystems, inc.;]. Thermal oxidative degradation reactions of perfluoroalkylethers The mechanisms operative in thermal oxidative degradation of Fomblin Z and hexafluoropropene oxide derived fluids and the effect of alloys and additives upon these processes are investigated.

The nature of arrangements responsible for the inherent thermal oxidative instability of the Fomblin Z fluids is not established. Thermal oxidative degradation reactions of perfluoroalkylethers. By K.

Paciorek, T. Ito and R. Kratzer. Abstract. The mechanisms operative in thermal oxidative degradation of Fomblin Z and hexafluoropropene oxide derived fluids and the effect of alloys and Author: K. Paciorek, T. Ito and R. Kratzer. Abstract. The thermal and thermal oxidative behavior of perfluoroalkylethers alone and in the presence of metals, metal alloys, oxides and halides is reviewed.

The correlation between processes at elevated temperatures and under boundary lubrication conditions and the effect of structural arrangements on stability and ease of reaction with metals are by: Ind.

Eng. Chem. Prod. Res. Dev. All Publications/Website. OR SEARCH CITATIONS. The E a for the thermal and thermo-oxidative degradation was definitely different, especially at high conversion. Thermal oxidative degradation reactions of perfluoroalkylethers book, the E a for thermo-oxidative degradation was much lower than that for thermal degradation, suggesting that the decomposition in oxygen was much easier than that in the inert environment.

Secondly, the departure from linear regression took place at α > for thermal degradation while at α > for the thermo-oxidative degradation. Oxidative degradation involves the disintegration of macromolecules by the action of oxygen on the substrate (oxidation).

Free radicals are formed which react with oxygen-producing oxy- and peroxy-radicals. These, on the other hand, can participate in many reactions: they may react with each other or remove hydrogen from polymer chains.

Abstract. The reaction of products of thermal and thermal oxidative degradation of polyvinyl chloride with barium hydroxide was studied. The degree of binding of chlorine and carbon atoms from polyvinyl chloride in reactions of barium hydroxide with hydrogen chloride and carbon dioxide formed by degradation and oxidation of the polymer was studied in relation to the hydroxide/polymer.

A study was made of the thermal oxidative degradation of linear polydimethylsiloxanes and polydimethylelementosiloxanes.

The degradation process is composed of two reactions: oxidation of the organic groups and degradation of the main chains of the molecule. The insertion of hetero atoms or groups in the dimethylsiloxane chain can sharply increase the thermal oxidative stability of the.

Chapters in this book are contributed by the experts working on thermal degradation and analysis of the wide variety of advanced and traditional materials.

Each chapter discusses the material, its possible application, behavior of chemical entities when exposed to high-temperature environment and mode and the mechanistic route of its decomposition. The oxidative degradation of poly (methyl methacrylate), PMMA, has been investigated at temperatures up to °C.

Molecular oxygen protects PMMA against depolymerization at temperatures below about °C. At higher temperatures oxidative main-chain scission becomes very important as evidenced by molar mass determinations.

Oxidative degradation is an autocatalytic process of attack on the hydrogen atoms, to form hydroperoxides. The stability of polymers is thus inversely proportional to the number of hydrogen atoms with the carbon atoms present in the polymer chain.

The degradation is. Abstract. The perfluoropolyether (PFPE) class of lubricants has been widely used for numerous special tribological applications because of their superb oxidative and thermal stability properties and low vapor pressure.

One of large application includes magnetic recording disks and metal evaporated tapes for computer data storage (Bhushan, ). Commonly used lubricants for topical lubrication include. Chemical degradation of lubricant fluids of perfluoropolyether (PFPE), such as Fomblin Z-DOL, Fomblin AM, Fomblin Z, Demnum SP-3, and Demnum SA, with bivalent metal ions was examined.

The respective reaction mechanisms involve an ether cleavage process which is caused by the coordination of metal ions with oxygen atoms in the main chains of the PFPE. in temperature above 93°C (°F), the rate of oxidation doubles. Thermal Degradation Thermal degradation or thermal cracking is the breaking of carbon–carbon bonds in the fluid molecules by adding heat in excess of the fluid’s recommended maximum bulk temperature.

The reaction may either stop at that point – resulting in smaller. Thermal-oxidative induced degradation behaviour of polyoxymethylene (POM) copolymer detected by TGA/MS March Polymer Degradation and Stability 91(3) Thermal and oxidative degradation of polymers.

Hawkins The rate at which various polymers oxidize and the extent of the reaction is influenced both by the physical and by the chemical structure of the particular polymer. Important morphological changes may also occur as a result of oxidation.

Polymer degradation by oxidative reactions. The intrinsic poor thermal stability of layered LiNixCoyMn1–x–yO2 (NCM) cathodes and the exothermic side reactions triggered by the associated oxygen release are the main safety threats for their large-scale implantation.

In the NCM family, it is widely accepted that Ni is the stability troublemaker, while Mn has long been considered as a structure stabilizer, whereas the role of Co. Thermal and Oxidative Degradation of Poly(methyl metha-crylate): Weight Loss, Macromolecu ().

[4] Atsushi Inaba and Takashi Kashiwagi, A Calculation of Thermal Degradation Initiated by Random Scission. Steady-State Radical Concentration, Macromolecu (). [5] Atsushi Inaba and Takashi Kashiwagi, A. The thermal degradation of sodium hyaluronate, xanthan and methylcellulose was evaluated by thermogravimetric and infrared analysis.

Kinetic parameters such as activation energy and pre. Organic materials undergo degradation reactions in the presence of oxygen. As a result, numerous oxidation products are formed such as, e.g. peroxides, alcohols, ketones, aldehydes, acids, peracids, peresters or y-lactones.

Elevated temperatures, heat, and catalysts, such as metals and metal ions, assist oxidation. High-Shear Reology and Shear Degradation of Aqueous Polymer Solutions,” Thermal Oxidative Degradation Reactions of Linear Perfluoroalkylethers,” Thermal Oxidative Studies of Poly(hexafluoropropene Oxide) Fluids,” Journal of Applied Polymer Science, Vol.

Thermal degradation processes of perfluoropolyethers, Fomblin Y, Krytox, and Demnum, catalyzed by Lewis acid (AlCl3) were examined. 19F NMR analyses of degraded materials revealed that the acid. Mateus Teixeira, Ignácio Del Hoyo, Fernando Wandrowelsti, Vitoldo Swinka-Filho, Marilda Munaro, Evaluation of thermal degradation in isotactic polypropylene films used in power capacitors, Journal of Thermal Analysis and Calorimetry, /s,2, (), ().

This paper describes the effect of surface treatment (nitriding), coating chemistry and architecture in preventing corrosion/oxidation of M50 steel and thermo-oxidative degradation of Fomblin® fluid.

Although thermal degradation is defined as an oxygen free process it is difficult in practise to completely exclude oxygen. Where this is the case thermal oxidation is to be expected, leading to the formation of free radicals by way of hydroperoxides.

These may then participate in thermal degradation reactions, accelerating the rate of breakdown. This work presents a new strategy for industrial flue gas purification with TiO2-based photocatalysis technology, which could be achieved by a novel dual-stage circulating photocatalytic reactor.

A lab-scale fixed bed reactor is utilized to investigate the performance of photocatalytic toluene degradation and inactive catalyst regeneration by thermal/UV treatment. The relationships between. Nevertheless, oxidative degradation in olive oil is the most important cause of an unfavorable sensory perception.

This chapter revises the oxidative deterioration of olive oil considering enzymatic oxidative deterioration, autoxidation, and photosensitized oxidation.

Chemical oxidation using peracetic acid (PAA) can be enhanced by activation with the formation of reactive species such as organic radicals (R–O•) and HO•.

Thermal activation is an alternative way for PAA activation, which was first applied to degrade micropollutants in this study.

PAA is easily decomposed by heat via both radical and nonradical pathways. Our experimental results suggest. The breakdown products can be accounted for by chain scission and transfer reactions. The formation of a large proportion of residue implies that crosslinking reactions play an important part in the degradation.

Lipid oxidation is a free radical chain reaction that leads to the development of unpleasant flavour and taste, loss of nutrients and formation of toxic compounds [7, 8].Consequently, the shelf life and the final use of any lipid depend on its resistance to oxidation or oxidative stability [].The term lipid oxidation usually refers to a three consecutive reactions or stages, known as.The oxidative degradation of isotactic polypropylene films coated on well‐defined Cu(Cu 2 O), CuOand CuO films in a temperature range of 90–°C in a quartz‐spoon‐gauge‐reaction vessel was catalytic reaction has been compared with the oxidation of .