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  • Polymer and Materials Science  (15)
  • STRUCTURAL MECHANICS  (3)
  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 49 (1961), S. 238-240 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Tab.
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  • 2
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: 2,3,6-Glucose-tricarbanilate prepared by degradation of cellulosetricarbanilate in 1-hydroxy-2-methoxy-ethane in presence of p-toluenesulfonic acid was condensed with phosphorpentoxide in a mixture of chloroform-dimethyl sulfoxide. Light scattering measurements gave degrees of polymerization up to 640. Contrarily to cellulose- and amylosetricarbanilates there was no definite relation between the STAUDINGER-Indices and molecular weights. Also no angular dependence of the scattered light was found. The products therefore are branched. The side chains are bound to the carbanilate groups, for after alkaline saponification of the polyglucosans the degrees of polymerization decrease to about 60. Degradation experiments with α-amylase and cellulase, optical rotation in tetraethylammoniumhydroxide and viscosity measurements of polyglucosans compared with those of different cellodextrins showed clearly that only 1,4-β-glucosidic linkages are present in the synthetic polysaccharides and that the products are not branched.
    Notes: 2,3,6-Glucosetricarbanilat  -  aus Cellulosetricarbanilat durch Alkoholyse in 1-Hydroxy-2-methoxy-äthan in Gegenwart von p-Toluolsulfosäure hergestellt  -  wurde in Chloroform/Dimethylsulfoxid durch Phosphorpentoxid kondensiert. Streulichtmessungen der Polykondensate ergaben Polymerisationsgrade bis 640. Zum Unterschied von Cellulose- und Amylosetricarbanilaten wurde keine eindeutige Beziehung zwischen STAUDINGER-Indices und Molekulargewichten gefunden. Die Streulichtintensität ergab keine Winkelabhängigkeit. Die Produkte müssen daher verzweigt sein. Die Seitenketten sind an die Carbanilatgruppen gebunden, denn nach alkalischer Verseifung lagen die Polymerisationsgrade bei ca. 60. Aus Abbauversuchen mit α-Amylase und Cellulase, Drehwerten in Tetraäthylammoniumhydroxid und vergleichenden Viskositätsmessungen an den Polyglucosanen und verschiendenen Cellodextrinen geht hervor, daß nur 1,4-β-glucosidische Bindungen in den synthetischen Polysacchariden vorliegen und daß die Produkte unverzweigt sind.
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  • 3
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: The radiotracer technique as a means to investigate the corrosion of zirconium, tantalum, and a Ta-40Nb alloy in fluoride containing azeotropic nitric acidZirconium and tantalum as well as the tantalum 40% niobium alloy are of considerable technical importance due to their high corrosion resistance against numerous corrosive media. With respect to corrosion testing in analytically pure azeotropic nitric acid in the temperature range between 20 and 121°C, corrosion rates were determined for zirconium: 7 · 10-6 to 5 · 10-4 mm/y, for tantalum: 10-8 to 4 · 10-6 mm/y, and for the Ta-40Nb alloy: 2 · 10-7 to 8 · 10-6 mm/y [1]. These corrosion rates will be markedly increased by adding small amounts of fluorides or by fluoride impurities.The radiotracer method after neutron activation was applied to determine the corrosion rates in azeotropic fluoride containing nitric acid. Even minute additions of fluorides strongly affect the corrosion resistance of zirconium. In the range between 0.15 and 10 ppm F- and at a temperature of 108°C, corrosion rates between 5.3 · 10-3 and 3.1 mm/y were measured. It was impossible to establish a limit for the fluoride concentration, below which the corrosion rate of zirconium will not be adversely influenced.The corrosion rates of tantalum and the Ta-40Nb alloy are considerably increasing above a fluoride concentration of 10 ppm. The highest corrosion rates measured were between 8.4 · 10-3 mm/y at 50°C/280 ppm F- and 1.4 · 10-2 mm/y at 110°C/320 ppm F-. Within the range of this investigation, the corrosion resistance of tantalum was higher than that of the Ta-40Nb alloy by one order of magnitude.The corrosion resistance of zirconium and tantalum was not influenced by any treatment of the samples before testing.
    Notes: Wegen ihrer hohen Korrosionsbeständigkeit gegenüber zahlreichen Angriffsmitteln sind Zirconium und Tantal sowie die Legierung Tantal-40Niob von großer technischer Bedeutung. Die bisher in azeotroper Salpetersäure p.a. zwischen 20 und 121°C gemessenen Abtragungsraten liegen für Zirconium zwischen 7 · 10-6 und 5 · 10-4 mm/a, für Tantal zwischen 10-8 und 4 · 10-6 mm/a und für die Legierung Ta-40Nb zwischen 2 · 10-7 und 8 · 10-6 mm/a [1]. Diese Abtragungsraten werden durch geringe Fluoridzustände oder -verunreinigungen wesentlich erhöht.Mit der Radiotracermethode nach Neutronenaktivierung wurden die Abtragungsraten in azeotroper, fluoridhaltiger Salpetersäure bestimmt. Zirconium ist schon gegen kleinste Fluoridspuren sehr empfindlich. Im untersuchten Bereich von 0.15 bis 10 ppm F- liegen bei 108°C die Abtragungsraten zwischen 5.3 · 10-3 und 3.1 mm/a. Eine Grenzkonzentration, unterhalb der das Fluorid die Korrosionsgeschwindigkeit nicht mehr beeinflußt, kann für Zirconium nicht angegeben werden.Bei Tantal und der Legierung Ta-40Nb nimmt oberhalb einer Grenzkonzentration von 10 ppm F- die Korrosionsgeschwindigkeit stark zu. Die höchsten Abtragungsraten liegen zwischen 8.4 · 10-3 mm/a bei 50°C/280 ppm F- und 1.4 · 10-2 mm/a bei 110°C/320 ppm F-. Dabei ist Tantal über den gesamten erfaßten Bereich um etwa das Zehnfache beständiger als die Legierung Ta-40Nb.Sowohl bei Tantal als auch bei Zirconium stellt sich die Abtragungsrate unabhängig von Vorbehandlungen ein.
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  • 4
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A model system was developed to study the influence of the rubber formulation and/or the aging conditions on the adhesion between brass and rubber. The bonding compounds were vulcanized on thin, homogeneous brass layers that had been prepared by sputtering onto special polymeric substrates; some of these compounds were steam-aged under controlled conditions subsequently. After the separation of the polymeric film, combined analytical electron microscopy (transmission electron microscopy/energy dispersive spectroscopy; TEM/EDS) and sputter neutral mass spectrometry (SNMS) analyses were performed. While the TEM/EDS studies offer a detailed insight into the morphological structure of the interphase, the SNMS depth profiles allow a rapid and reliable differentiation between various rubber formulations. With these model samples the beneficial effect of boric acid esters on the adhesion of cobalt-containing bonding compounds, which is observed in a typical short-term adhesion test after steam-aging, can be explained: boric acid esters act with cobalt salts as corrosion inhibitors for brass, preventing the growth of a thick intermediate ZnO/Zn (OH)2 layer that is the starting point for delaminations.
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  • 5
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The short chain branching in low density polyethylene obtained under various conditions were determined by γ-irradiation followed by gaschromatography of the gaseous scission products. The pressure and temperature of polymerization were found to affect the kind and number of branchings. The branching structure and reaction parameters are related and discussed on a kinetic concept.
    Notes: Die Kurzkettenverzweigung von unter verschiedenen Bedingungen synthetisierten Hochdruckpolyethylenen wurde mit Hilfe der γ-Bestrahlung und nachfolgender gaschromatographischer Analyse der Spaltgase bestimmt. Es wurde experimentell belegt, daß Reaktionsdruck und Polymerisationstemperatur Art und Anzahl der Seitenzweige beeinflussen. Verzweigungsstruktur und Reaktionsparameter werden zueinander in Beziehung gesetzt und auf der Grundlage kinetischer Überlegungen diskutiert.
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  • 6
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The Ti5Ta alloy shows interesting corrosion behaviour and is becoming technologically important, e.g. for chemical plant construction. Welding and further mechanical tests gave good mechanical properties. Therefore, the corrosion of this alloy was studied in comparison with the corrosion of unalloyed Ti and Ta. The samples were corroded for up to 24 days in hot 67.5% nitric acid.The resulting surface layers were investigated with SEM, transmission electron microscopy (TEM), energy dispersive x-ray microanalyses (EDX), AES and sputtered neutral mass spectrometry (SNMS). Under these conditions, the oxide growth seems to be dependent on the orientation of the crystallites at the surface, which was not observed under milder attack. When Ti5Ta samples were immersed for 5 days in boiling HNO3, the oxide layer was ∼300 nm thick and a particular crack pattern developed on some grains during drying in air at room temperature. This was observed only for oxide layers thicker than 300 nm.After corroding Ti5Ta in boiling HNO3 we observed a TaTi atomic ratio of up to 1:1 using ESCA and up to 5 μm thick Ta oxide-rich scales. The selected area diffraction pattern in the TEM indicates that the oxide film may contain mixed Ti/Ta oxides. The extraordinary Ta oxide enrichment, which is due to the selective dissolution process of Ti, is believed to cause the good corrosion resistance of the alloy. It was not observed after heat treatment in air up to 800 °C or after corrosion tests in HNO3 at room temperature.
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  • 7
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The wave number at maximum intensity, half width and integral absorption of model polyethylenes were determined. The line shape profiles of the δs(CH3)-vibration are statistically evaluated by momentum analysis. The measured and calculated spectral parameters are correlated with the kind of branching. The consequences for the analysis of the distribution of side chains having different length in high pressure polyethylene are discussed.
    Notes: Von methyl-, ethyl-, butyl- und hexylverzweigten Modellpolyethylenen werden die Wellenzahlen am Intensitäts-maximum, die Halbwertsbreiten und die integralen Absorptionen gemessen. Die Linienformprofile der δs(CH3)-Schwingung werden auf der Grundlage einer Momentanalyse einer statistischen Auswertung unterzogen. Der Verlauf der gemessenen und berechneten spektralen Parameter wird mit der entsprechenden Verzweigungsart korreliert. Die Konsequenzen für eine Analyse der Verteilung der im Hochdruckpolyethylen enthaltenen unterschiedlich langen Seitenketten werden diskutiert.
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  • 8
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Solutions and low molecular fractions of the reaction products of thermosetting epoxides based on bisphenol-A-diglycidylether (BADGE) and butane-1,4-diol (BD) with Mg(ClO4)2. 2H2O as accelerator were investigated by means of GPC, FTIR, and high resolution 13C-NMR. Conclusions concerning the development of the structure were drawn.
    Notes: Mittels GPC, FTIR und hochauflösender 13C-NMR wurden Lösungen sowie niedermolekulare Fraktionen der bei der Heißhärtung von Epoxiden auf der Basis von Bisphenol-A-Diglycidethern (BADGE) mit Butan-1,4-Diol (BD) in Gegenwart von Mg(ClO4)2. 2H2O als Beschleuniger entstehenden Reaktionsprodukte untersucht und Aussagen über die Strukturbildung getroffen.
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  • 9
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Based on an appropriate line shape function the superposition of CH3 and CH2 absorptions of polyethylene between 1330 and 1400 cm-1 was separated into five constitutive bands, two of them being assigned to methyl vibrations. The different length of short branches in high pressure polyethylene enables this separation. Additional characteristics of the line shape and, thus, the fraction of contributing structures are discussed. As a result, the overall branchings and the fraction of ethyl branchings are discerned.
    Notes: Die überlagerten CH3/CH2-Absorptionen der Polyethylenkette im Bereich von 1330 bis 1400 cm-1 werden durch Vorgabe einer geeigneten Linienformfunktion in die Einzelkomponenten zerlegt. Der Komplex besteht aus fünf Teilbanden, zwei werden den Schwingungen der Methylgruppe zugeordnet. Ursache dafür ist die unterschiedliche Länge der kurzen Seitenketten im Hochdruckpolyethylen. Weitere spektrale Größen, die das Bandenprofil und damit auch die Konzentration der anteiligen Strukturen im Komplex bestimmen, werden mitgeteilt. Im Ergebnis der Untersuchungen erhält man neben der Aussage über die Gesamtverzweigung eine weitere Information über den Anteil an Ethylverzweigungen im Produkt.
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  • 10
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The extinction coefficients of the CH3 deformation vibrations of short chain branchings in saturated polymeric hydrocarbons was determined in dependence on the length of side chains in model substances. The number of CH2 groups arranged between the main chain and methyl group of alkyl branchings affects essentially the intensity of the absorption at 1378 cm-1. The results were applied in the quantitative evaluation of CH3 vibrations for the calculation of the number of branchings in high pressure polyethylene.
    Notes: Die Extinktionskoeffizienten der CH3-Deformationsschwingung von kurzen Kettenverzweigungen in gesättigten polymeren Kohlenwasserstoffen wurden in Abhängigkeit von der Seitenkettenlänge an Modellsubstanzen ermittelt. Die Zahl der CH2-Gruppen, die sich zwischen Hauptkette und Methylgruppe der Alkylverzweigung befinden, beeinflußt wesentlich die Intensität der Absorption bei 1378 cm-1. Die Ergebnisse werden auf die quantitative Auswertung der CH3-Schwingung zur Berechnung von Verzweigungszahlen im Hochdruckpolyethylen angewendet.
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