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  • 1
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Résumé Etude par ATD et par spectroscopie infrarouge (IR) de l'effet de la teneur en antioxydant (Néozone D) et en catalyseur d'oxydation (cuivre dispersé) sur l'oxydation du polyéthylène fondu, en conditions non isothermiques (échauffement des échantillons à vitesse constante). L'augmentation de la teneur en antioxydant ou en catalyseur d'oxydation donne des résultats similaires, c'est-à-dire une diminution de l'épaisseur de la couche superficielle oxydée, et, par suite, de la quantité oxydée totale des échantillons de polyéthylène. Ceci est dû à l'augmentation de la vitesse de l'oxydation du polymère.
    Abstract: Zusammenfassung Differentialthermoanalyse (DTA) und Infrarotspektroskopie (IR) wurden zur Untersuchung der Wirkung des Gehaltes an Antioxidantien (Neozone D) und Oxidierungskatalysator (dispergiertes Kupfer) auf die Oxidation von Polyäthylenschmelze unter nicht-isothermischen Bedingungen (unter Aufheizung der Proben mit konstanter Geschwindigkeit) eingesetzt. Die Zunahme des Gehaltes an Antioxidanz oder Oxidierungskatalysator ergibt ähnliche Ergebnisse, d. h. Herabsetzung der Stärke der oxidierten Oberflächenschicht und, dementsprechend, der Gesamtoxidationsmenge in den Polyäthylenproben. Dies ist der Zunahme der Oxidationsgeschwindigkeit des Polymers zuzuschreiben.
    Notes: Abstract Differential thermal analysis (DTA) and infrared (IR) spectroscopy have been used to investigate the effects of an antioxidant (neozone D) and an oxidation catalyst (dispersed copper) on polyethylene melt oxidation under nonisothermal conditions (samples were heated at a constant rate). An increase in the content of the antioxidant or the oxidation catalyst gives similar results: a decrease in the thickness of the oxidized surface layer and accordingly in the total amount of oxidation in polyethylene samples. This is due to an increase in the rate of oxidation of the polymer.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Oxidation of polyethylene (PE) melts in contact with metals (Cu, Pb, Au, Al, Zn, Ag) has been studied by infrared spectroscopy and differential thermal analysis (DTA). These metals may be divided into two groups, depending on their activity for oxidizing PE: namely, high-activity metals (Cu, Pb, Ag, Zn) and low-activity metals (Al, Au). During the oxidation of PE in contact with high-activity metals dissolution of the surface layer of metal is observed with accumulation of metal-containing compounds (salts of carboxylic acids) in the bulk of the polymer. With low-activity metals these phenomena are not observed. The rate of oxidation of PE on low-activity metals approaches the oxidation rate of nonmetals (polytetrafluoroethylene and inorganic glass). With certain high-activity metals (Cu, Pb) the process of oxidation is accelerated only in the early stage of oxidation; then the oxidation rate slows down and the oxidation process ceases. PE films separated from metal after being oxidized on it possess chemical memory, i.e., their oxidation rate depends on the nature of the metal with which they had been in contact, and on the duration of the contact oxidation. The effect of salts of carboxylic acids (metal stearates) on the oxidation of PE melts was also studied. Based on the data obtained, it is concluded that the rate of oxidation of PE melts on high-activity metals is controlled by metal-containing compounds which are the products of contact reactions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung DSC, thermogravimetrische Analyse (TG) und infrarot (IR) Spektroskopie wurden zur Untersuchung der während der thermischen Oxidation von in Belägen und metallgefüllten Filmen enthaltenem Polyäthylen, Polypropylen und Penton stattfindenden chemischen und physikalischen Veränderungen (Kristallinität, Anhäufung stickstoffhaltiger Gruppen usw.) eingesetzt. Hierbei wurden die Stärke der Polymerschicht und die katalytische Aktivität des Metalls in Betracht genommen.
    Abstract: Резюме Методами дифференци альной сканирующей калориметрии, термог равиметриче ского анализа и инфра красной спектроскоп ии изучены химические и физичес кие изменен ия (кристалличность, н акопление кислородс одержащих групп идр.) при термиче ском окисл ении полиэтилена, пол ипропилена и пентона в покрытиях и наполнен ных металлами пленках с учетом толщ ины слоя полимера и каталитической акти вности металла.
    Notes: Abstract Differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and infrared (IR) spectroscopy have been used to examine the chemical and physical changes (crystallinity, accumulation of oxygen-containing groups, etc.) during thermal oxidation of polyethylene, polypropylene and Penton contained in coatings and metalfilled films, taking into account the thickness of the polymer layer and catalytic activity of the metal.
    Type of Medium: Electronic Resource
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