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  • Polymer and Materials Science  (55)
  • 2000-2004
  • 1975-1979  (17)
  • 1970-1974  (18)
  • 1955-1959  (20)
  • 1
    Electronic Resource
    Electronic Resource
    Die Anwendung von Titangußteilen im MRCA Triebwerk RB 199 zur Herstellung eines komplexen Zwischengehäuses (1975)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 6 (1975), S. 361-367 
    Details
    ISSN: 0933-5137
    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 Use of Titanium Castings to Produce a Complex Shaped Intermediate Casing of RB 199.This paper describes the present position on a highly stressed casing and its functions in the RB 199-34 R engine. When the parts of the casing are made from solid forged titanium billets, up to 93% of the material used is machined away. For this reason, the most complicated parts of the casing were procured as castings and welded together by TIG welding. The paper describes the present quality standard of the titanium castings. The tests on the materials and their mechanical properties show that the castings are inferior to the forgings only with respect to their HCF behaviour and their elongation at rupture. Macroscopic flaws are not entirely inevitable but can be detected by X-ray tests. The future prospects for titanium castings are considered favourable.
    Notes: Der Bericht beschreibt die Lage eines hochbeanspruchten Gehäuses und dessen Funktionen im Triebwerk RB 199-34 R. Bei der Herstellung der Einzelteile des Gehäuses aus massiv geschmiedeten Titanblöcken wird bis zu 93% des eingesetzten Materials zerspant. Die kompliziertesten Partien des Gehäuses wurden deshalb als Gußteil bezogen und mittels WIG-Schweißung verbunden. Der Bericht beschreibt den heutigen Qualitätsstand der Titangußteile. Die Ergebnisse der Werkstoff- und Festigkeitsuntersuchungen weisen nur im HCF-Verhalten und der Bruchdehnung Nachteile des Gusses gegenüber dem geschmiedeten Material aus. Makroskopische Fehler sind nicht vollständing vermeidbar, aber durch Röntgenprüfung nachzuweisen. Die künftigen Aussichten des Titangusses werden positiv beurteilt.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mawe.19750061102
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  • 2
    Electronic Resource
    Electronic Resource
    Hochtemperatur-Korrosion durch Schwefelverbindungen in der ErdölraffinationVorgetragen am 5. 6. 1958 auf dem II. Kongreß der Europäischen Föderation für Korrosion in Frankfurt/M. (1959)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 10 (1959), S. 74-77 
    Details
    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: High Temperature Corrosion in Petrol Refining by Sulfur CompoundsAt temperatures above 260°C only stainless, highly alloyed steels resist the attack of the most corrosive agent in petrol refining which is hydrogen sulfide. For high temperature corrosion by hydrogen sulfide, the influences of the duration of wear, the concentration of the hydrogen sulfide, the pressure, the properties of the refined petrol and the quality of the steel are of essential importance besides of the effects of temperature. The author reports on last years investigations in BP-research station on the corrosion of stainless steels by hydrogen sulfide at high temperatures. The corrosion of the surface, the inter-crystalline corrosion and the stress corrosion of steels are discussed in detail.
    Notes: Dem Angriff des wesentlichsten korrosiven Agens in Erdölraffinerien, dem Schwefelwasserstoff, bei hohen Temperaturen (über 260°C) widerstehen praktisch ausschließlich rostfreie, hochlegierte Stähle. Bei der Hochtemperatur-Korrosion durch Schwefelwasserstoff sind neben der Temperatur auch Beanspruchungsdauer, Schwefelwasserstoff konzentration, Druck, Beschaffenheit des zu raffinierenden Öles und die Stahlqualität von Einfluß. Verfasser berichtet über die in den letzten Jahren in der BP-Research Station durchgeführten Untersuchungen über die Korrosion von rostfreien Stählen durch Schwefelwasserstoff bei hohen Temperaturen, wobei allgemeine Oberflächen-korrosion, interkristalline Korrosion und Spannungskorrosion der Stähle eingebend behandelt werden.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19590100204
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  • 3
    Electronic Resource
    Electronic Resource
    Electrostatic interactions in polyglutamic acid (1973)
    New York : Wiley-Blackwell
    Biopolymers 12 (1973), S. 845-856 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational energy estimates were made for completely charged polyglutamic acid with different assumptions concerning the placement of side chain charge. Viewed as a helix, the minimum energy structure is somewhat affected by the side-chain charge placement. The average energy of the chain viewed as a random coil is equal to or less than the average energy of the chain viewed as a helix. Unlike the polyacrylate chain, nearest-neighbor charge interaction is shown to increase the chain dimensions. Although the calculations are approximate there is little evidence to suggest that isolated polyglutamate molecules in the absence of added electrolyte should behave as rods or that there are significant amounts of locally ordered structures. Presently no experimental results exist under conditions appropriate to isolated molecular calculations.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1973.360120413
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  • 4
    Electronic Resource
    Electronic Resource
    Effect of residual side chain blocking groups and side chain charge on polypeptide conformation in aqueous solution (1973)
    New York : Wiley-Blackwell
    Biopolymers 12 (1973), S. 835-843 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The circular dichroism (CD) spectrum of poly-L-lysine and poly-L-glutamic acid has been investigated in the presence of a small percent of side-chain blocking groups. The blocking groups benzyl, methyl, and carbobenzoxy show qualitatively similar effects. Less than five mole percent of aromatic blocking groups alters the CD spectrum. Consequently, unsuspected blocking groups may account for the variation observed in CD spectra of these polymers. A weak CD band at 235-240 nm was observed for the disordered unblocked polymer even in the absence of electrolyte. Viscosity data indicate that in salt-free solutions these chains at neutral pH still behave as random coils though with reduced conformational freedom, in contrast to some polyelectrolytes which behave as rigid rods in the absence of electrolyte. The viscosity data bring into question the relevance of isolated molecule conformational calculations to experimental CD spectra.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1973.360120412
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  • 5
    Electronic Resource
    Electronic Resource
    Thermodynamic parameters of the helix-coil transition in polypeptide chains. III. Random copolymers of L-leucine with L-glutamic acidThe preceding two papers of this series are Refs. 1 and 2. (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1739-1753 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Conformational transitions induced by pH changes in random copolymers of leucine and glutamic acid have been studied. Significant differences were observed in the potentiometric titration curves of copolymers with small (up to 4%) and large leucine contents. The helical stability of copolymers with small leucine content, determined from titration curves by the Zimm and Rice method, decreases slightly with an increase in the leucine content, whereas the helical stability of copolymers with large leucine content increases sharply with an increase of the leucine content. It is shown that copolymers with large leucine content aggregate in the region of transition into the helical state, but the increase of their helical state stability is not connected with intermolecular aggregation, as it was also observed for a nonaggregating fraction isolated from one of the copolymers by gel chromatography. A conclusion is made that the helix-coil equilibrium constant s for leucine does not itself exceed the s constant for uncharged polyglutamic acid. The stabilization of the helical state in copolymers with large leucine content is due to intramolecular aggregation of helices in these copolymers. The analysis of the leucine residue distribution between helical and nonhelical regions in globular proteins also gives no real arguments to ascribe special helix-forming properties to leucine.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140814
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  • 6
    Electronic Resource
    Electronic Resource
    Development of blood-compatible elastomers. III. Hematologic effects of avcothane intra-aortic balloon pumps in cardiac patientsThe intra-aortic balloon pump treatment of cardiac patients at the Massachusetts General Hospital was supported in part by U.S. Public Health Service Contract No. PH43-67-1443 (MIRU). (1972)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 6 (1972), S. 129-154 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: As of this date, tri-segmented intra-aortic balloons made from Avcothane-51 elastomer were applied in the counterpulsation treatment of about 80 cardiac patients. The combined effects induced by the implanted elastomer and the hemodynamics of pumping are analyzed by means of hematologic changes observed in a set of 28 patients who were treated at the Massachusetts General Hospital for an average period of about 4 days, and represent a widely diversified group in terms of their clinical conditions. In no case were, any significant adverse hematologic effects induced by this assist device whether the hosts had been anticoagulated or not heparinized at all. While platelet levels were somewhat affected by the assist device, the particular conditions of the patient appear to have an effect of at least, equal magnitude. In addition to platelet levels steadily decreasing with pumping time, changes in platelet levels similar to the pattern of “platelet tide” occurred with about equal frequency. Monitored in terms of erythrocyte counts and plasma hemoglobin levels, no significant degree of hemolysis could be detected. Leukocyte counts in patients having above-normal levels at the beginning of pumping returned to normal while in other cases there were no significant changes. Fibrinogen, one of the plasma proteins most sensitive to foreign surfaces, showed levels increasing from subnormal to normal as a function of pumping time. The overall in vivo performance of Avcothane-51 balloons appers to be consistent with the state of the surfaces of recovered devices, showing only the presence of occasional adherent platelets upon examination by scanning electron microscopy.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820060410
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  • 7
    Electronic Resource
    Electronic Resource
    Poly α-ester degradation studies. IV. Rheological studies of polymer degradation (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 11 (1973), S. 2031-2043 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Farol-Weissenberg rheogoniometer has been used to follow molecular weight changes during the degradation of certain poly-α-esters in the melt state. By observing the change in melt viscosity at low shear rates it had been shown that the decomposition of the poly(isopropylidene carboxylate) is substantially first-order with respect to the molecular weight of the residual polymer. The derived kinetic parameters are in good agreement with those previously obtained by other techniques. This provides a substantial piece of supporting evidence for the view that degradation takes place predominantly by intramolecular ester interchange involving the formation of 1,1,4,4,-tetramethylglycollide. The introduction of β-chlorine atoms into the polymer structure leads to a more complex degradation pattern. Thus the presence of a single β chlorine atom per repeat unit, as in poly(3-chloro-2-methyl-2-hydroxypropionic acid) leads to a substantially similar dependence on molecular weight with the added complication of progressive crosslinking which becomes more apparent in later stages of the reaction. This crosslinking reaction plays an increasingly important part as the extent of chlorination of the polymer is increased. In addition, the presence of chlorine leads to an increased sensitivity of the degradation reaction to the presence of oxygen.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.170110822
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  • 8
    Electronic Resource
    Electronic Resource
    The radical initiation of vinyl polymerization by α.α.α′.α′-Tetrasubstituted dibenzyls (1972)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 157 (1972), S. 279-298 
    Details
    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: Im Temperaturbereich von 60 bis 100°C wird die radikalische Polymerisation von Styrol, Methylmethacrylat und Acrylnitril von α.α′-Dicyanodibenzylen ausgelöst, die in α-und α′-Stellung mit Ester-, Nitril-, Amid- oder Phenylgruppen disubstituiert sind. Bei 100 bis 110°C ist auch das α.α.α′.α′-Tetracarboxymethyldibenzyl aktiv. Vinylacetat und Vinylchlorid werden durch diese Initiatoren kaum polymerisiert.Fur die Polymerisation des Styrols wurden die Bruttogeschwindigkeitskonstanten Kp, für viele Dibenzyle und fur Peroxide vergleichbarer Aktivitat dilatornetrisch bestirnrnt. Norrnalerweise sind die Zeit-Urnsatz-Kurven rnit den Dibenzylen und den Peroxiden vergleichbar; das Tetracyanodibenzyl allerdings bewirkt nur eine unvollstandige Polymerisation.Der große Einfiuß von Substituenten in α-Stellung oder in den Phenylringen der Dibenzyle auf die Polymerisation des Styrols wird diskutiert. Dabei ist auch die Stereochernie wichtig. Die meso-Form des Dinitrildiesters ergibt eine 2.5- bis 3.5 ma1 schnellere Polyrnerisation als das dl-Isornere.Die Dissoziationsgeschwindigkeitskonstanten kd der Initiatoren wurden NMR-spektroskopisch aus der Linienbreite bestirnmt. Die Dinitrildiester sind gute Initiatoren, wahrend die α.α′-Dicyanodibenzyle rnit weiteren Nitril- oder Phenylgruppen in α- und α′-Stellung wenig geeignet sind. SchlieBlich wurde die 1.2-Addition einiger der Dibenzyle an Styrol im Ternperaturbereich von 120 bis 150°C rnit der Methode der chernisch induzierten KernPolarisation (CIDNP) untersucht.
    Notes: The radical polymerization of styrene, methyl methacrylate and acrylonitrile is initiated by α.α′-dicyanodibenzyls α.α′-disubstituted with ester, nitrile, amide or phenyl groups in the temperature range 60 to 100°C and by α.α.α′.α′-tetracarboxymethyldibenzyl at 100 to 110°C. Vinylacetate and vinylchloride show a low reactivity.The overall polymerization rate constants Kp have been determined dilatometrically for styrene initiated by a large number of dibenzyls and comparable peroxides. The styrene polymerization curves are generally comparable with those of peroxides. A notable exception is tetracyanodibenzyl.The strong influence of α- and ring-substituents in the dibenzyls on the styrene polymerization rate is discussed. The stereochemistry is also important : the meso α.α′-dicyanodibenzyls α.α′-disubstituted with ester groups give a 2.5 to 3.5 fold faster polymerization than their dl isomers.The initiator efficiency is related to the kd values, determined from NMR line width measurements. The α.α′- dicyanodibenzyls α.α′-disubstituted with ester groups are good initiators, while those with phenyl groups and nitrile groups are inefficient.Relevant to initiation and termination, the 1.2-addition of some of the dimers to styrene at 120 to 150°C has been studied with chemically induced dynamic nuclear polarization (CIDNP).
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1972.021570128
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  • 9
    Electronic Resource
    Electronic Resource
    On the coagulation of polymer latices by freezing and thawing (1959)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 37 (1959), S. 499-514 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The particle size characteristics of coagulates obtained by freezing and thawing emulsions of polymers which are hard and glassy at normal temperatures, particularly polystyrene and styrene copolymers, have been studied. It is shown that for a given polymer the particle size distribution is principally determined by the macrostructure of the frozen mass, such as the size of the ice crystals formed and the concentration of polymer in the initial emulsion. The effect of chemical structure of the polymer on the freezethaw coagulation process is discussed and from the results it is suggested that the usual concept of a second-order (glass) transition is not applicable to very fine latex particles of rigid polymers. This may also explain the formation of continuous films from fine latices at temperatures below the transition temperature of the bulk polymer.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1959.1203713219
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  • 10
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    Electronic Resource
    Effect of chemical structure on the softening point of substituted polystyrenes and related materials (1959)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 37 (1959), S. 515-532 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The concept of a limiting softening point, defined in relation to a partictilar standard test method (B. S. 1493) but otherwise only a function of the repeat unit structure of the polymer, is discussed. An approximate correlation of results obtained from different standard methods is given and its limitations analyzed. Limiting softening point data are given for polystyrene and 25 different substituted polystyrenes. Analysis of the results suggest the following: (1) the elevating effect of non-polar nuelear substituents is greatest in the o-position, and increases with the size of the substituent (2) in the p-position, large rigid groups elevate the softening-point whereas the reverse is true of flexible (articulated) groups; (3) effects of substituents are additive only where they produce the same hindrance to molecular motion, e.g., the effect of two Similar o-substituents is additive; in other cases, the softening point elevation is determined by the biggest single energy barrier which has to be overcome. (4)Inchlorine-substituted polystyrenes the L.S.P. can [in accordance with (3)] be determined by either polar or stenic factors, depending on the number and position of the substituents. It is also possible to classify the mechanisms by which substitution can elevate the L.S.P. of polystyrene, these being: (1) stiffening of the main-chain backbone; (2) intramolecular steric hindrance (e.g., o-substitution); (3) increased intermolecular steric hindrance; and (4) dipolar attraction. From a qualitative consideration of structural features in copolymers of styrene with substituted styrenes, it is deduced that many such copolymers should show a roughly linear variation of L.S.P. with composition.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1959.1203713220
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