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  • 1
    Electronic Resource
    Electronic Resource
    Stability of polymer composites as positive-temperature-coefficient resistors (1974)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 706-716 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This is a study of materials which are positive-temperature-coefficient resistors. Such materials, composed of conductive particles dispersed in a crystalline polymeric matrix, have been found to be of limited stability. An example is carbon black in high-density polyethylene. On repeated cycling through the anomaly temperature or on extensive heating at or above the anomaly temperature, the room temperature resistivity rises and the anomaly height falls to zero. This phenomenon has been shown to be caused by the absorption of oxygen by the polymer matrix which alters the structure, reduces the crystallinity, and induces an unusual form of crosslinking of a reversible nature.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760141009
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of diblock and homopolymer impurities on the morphology of triblock polymers (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 2079-2089 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Commercial triblock polymers (Kratons) consisting of polystyrene and a polydiene were characterized via gel permeation chromatography and small-angle x-ray scattering in order to determine the amount of free polystyrene and diblock material and to clarify the effect of these polymeric impurities on the morphology of solvent-cast samples. Gel permeation chromatography measurements revealed the Kratons to consist of 80-85% triblock, 15-20% diblock, and trace amounts of free polystyrene. Pure triblocks, impurity-doped pure triblocks, the Kratons, and a postpolymerically degraded Kraton were examined with regard to the effect of polymeric impurities on morphology. Small amounts (〈5%) of free polystyrene induce a regularization of the glassy domains, while increased amounts of this homopolymer apparently lead to diffuse phase boundaries. The presence of diblock polymer results in a loss of macrolattice details, indicating the presence of less ordered and more diffuse glassy domains.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1972.070160819
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  • 3
    Electronic Resource
    Electronic Resource
    Glass transition temperature as a guide to selection of polymers suitable for PTC materials (1973)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 13 (1973), S. 462-468 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: It has been shown that the only way to predict the size of the PTC effect displayed by a crystalline polymer when filled with conductive particles is through the knowledge of the glass transition point of the polymer. The size of the PTC anomaly is found to decrease sharply with rise in glass transition temperature and for a polymer to be a useful PTC material its glass transition must be below 0°C. It has not been possible to explain this relationship by any of the current theories of the PTC mechanism in filled polymers.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760130611
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  • 4
    Electronic Resource
    Electronic Resource
    Estimation of molecular weight error for concentration uncertainties in the intrinsic viscosity determination (1972)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 2435-2438 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1972.070160923
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  • 5
    Electronic Resource
    Electronic Resource
    Notiz zum Magnetischen Verhalten von Li3CrO4 (1974)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 408 (1974), S. 15-20 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Notice on the Magnetic Behaviour of Li3CrO4Li3CrO4, a smaragd green powder, is due to powder photographs (Guinier-Simon-technique) isotypic with orthorhombic HT—Li3PO4, a = 6.309, b = 10.851, c = 4.952 Å, Z = 4. Between 298 and 10K the Curie-Weiss-Law is obeyed with μ=1.60 B.M. and Θ=+10 K. Below 5 K ferromagnetism is observed. ESR measurements at 4.2 K and more pronounced at 1.8 K show anisotropy of the ligand field.
    Notes: Li3CrO4, ein smaragdgrünes Pulver, ist nach Guinier-Simon-Aufnahmen isotyp mit HT-Li3PO4, a = 6,309 Å, b = 10,851 Å, c = 4,952 Å, Z = 4. Zwischen 298 und 10 K wird das Curie-Weisssche Gesetz mit μ=1,60 B.M., Θ=+10K befolgt. Unterhalb von 5 K tritt überraschend Ferromagnetismus auf. ESR-Messungen bei 4,2 K und ausgeprägter bei 1,8 K zeigen eine Anisotropie des Ligandenfeldes.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19744080104
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  • 6
    Electronic Resource
    Electronic Resource
    Zur Kenntnis von Dinitrito-kobalt(III)-Komplexen. I Darstellung und Absorptions-Spektren der Dinitrito-di(äthylendiamin)-kobalt(III)-perchlorate (1974)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 408 (1974), S. 275-282 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Dinitrito Cobalt(III) Complexes. I. Preparation and Absorption Spectra of Di(ethylenediamine) Cobalt(III) PerchloratesCis and trans dinitrito diethylenediamine cobalt perchlorates could be prepared starting with carbonato and trans dichloro ethylenediamine cobalt perchlorate. Spectroscopic data are reported and compared with those of the corresponding dinitro complexes.
    Notes: Ausgehend von Carbonato- und trans-Dichloro-diäthylendiaminkobalt(III)-perchlorat konnten cis- und trans-Dinitrito-diäthylendiamin-kobalt(III)-perchlorate dargestellt werden. Ihre Spektren im sichtbaren Gebiet und UV werden mitgeteilt und mit den Spektren der entsprechenden Dinitrokomplexe verglichen.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19744080308
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  • 7
    Electronic Resource
    Electronic Resource
    Zur Kenntnis von Dinitrito-kobalt(III)-Komplexen. II Kinetik der Isomerisierung und der Umsetzung von cis- und trans-Dinitrito-di(äthylendiamin)-kobalt(III)-perchloraten mit Stickstoffwasserstoffsäure (1974)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 408 (1974), S. 283-292 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Dinitrito Cobalt(III) Complexes. II. Kinetics of Isomerisation and Reaction of Cis and Trans Dinitrito Di(ethylenediamine) Cobalt(III) Perchlorates with Hydrazoic AcidAfter a reinvestigation of the kinetic data of the nitrito-nitro isomerisation of cis and trans dinitrito-di(ethylenediamine) cobaltic perchlorate, the kinetics of the reactions between both coordination compounds and hydrazoic acid, to yield the diaquo compounds, nitrogen and dinitrogen oxide, has been studied by gasvolumetric measurements in the temperature range from 1 to 15°C. In azide buffer solutions both reactions proceed independently of pH, in two stages bimolecular with regard to the complex ion and hydrazoicacid. In both cases the first stage velocity constant is five times greater than the second constant. The cis-compounds react approximately three times faster than the trans-compounds. Possible reasons for the observed facts are discussed.
    Notes: Nach nochmaliger Ermittlung der kinetischen Daten der Nitritonitro-Isomerisierung von cis- bzw. trans-Dinitrito-di(äthylendiamin)-kobalt(III)-perchlorat wurde die Kinetik der Umsetzung der beiden Komplexverbindungen mit Stickstoffwasserstoffsäure zu den Diaquo-di(äthylendiamin)-Komplexen, Stickstoff und Distickstoffmonooxid gasvolumetrisch im Temperaturbereich von 1—15°C untersucht. In Azidpufferlösungen verlaufen die Reaktionen unabhängig vom pH in zwei Stufen bimolekular in bezug auf das jeweils vorliegende Komplexion und Stickstoffwasserstoffsäure, wobei die erste Geschwindigkeitskonstante etwa fünfmal größer ist als die zweite. Die cis-Verbindungen reagieren in beiden Stufen etwa dreimal rascher als die trans-Komplexe. Mögliche Gründe für diese Beobachtungen werden diskutiert.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19744080309
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  • 8
    Electronic Resource
    Electronic Resource
    Zur Bildung und Konzentration der aktiven Spezies löslicher Ziegler-Natta-Katalysatoren (1970)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 12 (1970), S. 175-183 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The rate of polymerisation of ethylene by the soluble ZIEGLER-NATTA-catalyst (C5H5)2Ti(C2H5)Cl/Al(C2H5)Cl2 was investigated in toluene as solvent. From the dependence of the initial rate of the polymerisation follows, that the primary complex, formed by the catalyst components, is not the active species of this system. The obtained dependences rather suggest, that the active species is to be viewed as an equilibrium product and the location of this equilibrium is determined by the ratio of the catalyst compounds in that manner, that only at high Al/Ti-ratios the charged Ti(IV)-compound is equal to the initial concentration of the active species. The existence of such an equilibrium is also suggested by the increase of the rate, occuring at lower Al/Ti-ratios, when polymer is falling out. The desactivation of propagating chains is of complex nature. Considerable desactivation of the active species by the aluminiumorganic compound is obtained.
    Notes: Es wurde die Geschwindigkeit der Polyreaktion von äthylen mit dem löslichen ZIEGLER-NATTA-Katalysator (C5H5)2Ti(C2H5)Cl/Al(C2H5)Cl2 in Toluol als Lösungsmittel untersucht. Aus der Abhängigkeit der Anfangsgeschwindigkeit der Polyreaktion von der Aluminiumalkylkonzentration ergibt sich, daß der aus den Katalysatorkomponenten sich bildende Primärkomplex nicht die aktive Spezies dieses Systems ist. Vielmehr sprechen die ermittelten Abhängigkeiten dafür, daß die aktive Spezies als Gleichgewichtsprodukt anzusehen ist und die Gleichgewichtslage vom Verhältnis der Katalysatorkomponenten bestimmt wird, derart, daß erst bei sehr hohen Verhältnissen Al/Ti die insgesamt eingesetzte Titan(IV)-Verbindung momemtan als aktive Spezies vorliegt. Für das Vorliegen eines solchen Gleichgewichtes spricht auch der für kleine Verhältnisse Al/Ti stets zu beobachtende Geschwindigkeitsanstieg nach dem Ausfallen des Polymeren. Die Desaktivierung der wachsenden Ketten ist komplexer Natur. Es zeigt sich, daß das Aluminiumorganyl in starkem Maße an der Desaktivierung der aktiven Spezies beteiligt ist.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1970.050120114
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  • 9
    Electronic Resource
    Electronic Resource
    Über eine anomale Teilchenbildungsphase bei der Emulsionspolymerisation von SBRHerrn Prof. Dr. Heinrich Hellmann zum 60. Geburtstag gewidmet (1974)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 39 (1974), S. 167-174 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: In the course of emulsion polymerization of SBR the rate of polymerization during the stage of particle formation is running through a significant maximum, if initiation takes place with a redox-system, consisting of the partially oil-, partially water-soluble components pinenehydroperoxide, ethylenediamine-tetraacetic acid, ferrous sulfate and rongolite. This anomaly is discussed by means of a reaction scheme, which, among other steps, postulates radical formation directly in the micelles themselves.
    Notes: Bei der Emulsionspolymerisation von SBR durchläuft die Polymerisationsgeschwindigkeit während der Teilchenbidungsphase ein ausgeprägtes Maximum, wenn als Initiator das aus den teils öl-, teils wasserlöslichen Komponenten Pinanhydroperoxid, Äthylendiamintetraessigsäure, Eisensulfat und Rongalit bestehende Redoxsystem eingesetzt wird. Diese Anomalie wird an Hand eines Reaktionsschemas diskutiert, das u. a. von einer Radikalbildung unmittelbar in den Mizellen ausgeht.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1974.050390114
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  • 10
    Electronic Resource
    Electronic Resource
    Zur nachkondensation von polyamiden im teilkristallinen zustandHerrn Prof. Dr. H. HELLMANN zum 60. Geburtstag gewidmet (1973)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 34 (1973), S. 165-175 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The molecular weight of polyamides can be changed by postcondensation in the solid state. The equilibrium molecular weight distribution in the partially crystalline polyamide can be calculated using reasonable assumptions. Under equal post-condensation conditions the calculation yields a higher molecular weight average for the partially crystalline material as compared with the amorphous one, while the type of the distribution function (SCHULZ-FLORY) remains nearly unchanged.
    Notes: Das Molekulargewicht von Polyamiden kann durch Nachondensation im festen Zustand verändert werden. Unter naheliegenden Annahmen läßt sich die Molekulargewichtsverteilung berechnen, die sich dabei im teilkristallinen Polyamid als Gleichgewichtszustand einstellt. Bei sonst gleichen Bedingungen ergibt sich ein höheres mittleres Molekulargewicht als in völlig amorphem Material, während sich der Typ der Verteilung (SCHULZ-FLORY) praktisch nicht ändert.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1973.050340111
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