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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 57 (1977), S. 15-27 
    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 viscosity of liquid mixtures exhibits a characteristic temperature dependence near the consolute point. For polymer solutions this phenomenon is well studied in the case of upper critical solution temperatures, whereas no such measurements exist in the vicinity of lower critical solution temperatures.Viscosity measurements were performed for the system cyclohexane/polystyrene (upper critical solution temperature) and for the system orthotrimethylformiate/diethylether/polystyrene (lower critical solution temperature). For the former system qualitative agreement with. the results of Debye and coworkers was found. The investigations in the vicinity of the lower critical solution temperatures also disclosed that an additional function is superimposed to the normal temperature dependence of the viscosity which leads to an increase in viscosity before demixing sets in. This behaviour can be described by an equation analogous to that used for lower solubility gaps.
    Notes: Die Viskosität flüssiger Mischungen zeigt in der Nähe des kritischen Entmischungspunktes eine charakteristische Temperaturabhängigkeit. für Polymerlösungen ist diese Erscheinung bei der oberen kritischen Entmischungstemperatur gut untersucht, während in der Umgebung der unteren kritischen Entmischungstemperatur keine derartigen Messungen vorliegen.ES wurden Viskositätsmessungen im System Cyclohexan/Polystyrol (obere kritische Entmischungstemperatur) und im System Orthotrimethylformiat/Diäthyläther/Polystyrol (untere kritische Entmischungstemperatur) durchgeführt. Beim ersten System ergab sich qualitative Übereinstimmung mit den Ergebnissen von Debye und Mitarbeitern. Die Untersuchungen in der Umgebung der unteren kritischen Entmischungstemperatur zeigten, daß auch hier dem normalen Viskositäts-Temperaturverlauf eine zusätzliche Funktion überlagert ist, die zu einem Viskositätsanstieg vor Eintritt der Entmischung führt. Dieses Verhalten läßt sich mit einer analogen Gleichung beschreiben, wie sie für untere Mischungslücken verwendet wurde.
    Additional Material: 7 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 139 (1986), S. 149-156 
    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: Polymethylmethacrylat (PMMA), Polybutylmethacrylat (PBMA) und Polydecylmethacrylat (PDMA) sind bei Normaldruck mit Toluol im Bereich zwischen Raumtemperatur und Siedepunkt des Lösungsmittels vollkommen mischbar. In Alkanen (C6 bis C10) und Pentanol-1 steigt die Löslichkeit mit der Länge der Seitengruppe des Polymeren: PMMA zeigt stets eine Mischungslücke im oben angegebenen Temperaturbereich, PBMA zeigt obere kritische Lösungstemperaturen (außer bei n-Hexan, das ein Nichtlösungsmittel ist), und PDMA ist mit allen untersuchten Alkanen vollständig mischbar. Alkohole (bis C4) sind Nichtlösungsmittel für PMMA, aber Theta-Lösungsmittel für PBMA und PDMA (außer Ethanol, das ein Nichtlösungsmittel für PDMA darstellt). Die Tieftemperaturentmischung von Ethanol/PBMA wird durch Druck zu tieferen Temperaturen verschoben.
    Notes: Poly(methylmethacrylate) (PMMA), poly(butylmethacrylate) (PBMA), and poly(decylmethacrylate) (PDMA) are completely miscible with toluene at normal pressure from room temperature up to the boiling point of the solvent. In alkanes (C6 to C10) and 1-pentanol the solubility increases with the length of the side chain of the polymer: PMMA always exhibits a solubility gap within the above temperature range, PBMA shows upper critical solution temperatures (except n-hexane, which is a non-solvent), and PDMA mixes completely with all alkanes under consideration. Alcohols (up to C4) are non-solvents for PMMA but theta solvents for PBMA and PDMA (except ethanol which is a non-solvent for the latter). The low temperature demixing of ethanol/PBMA is shifted towards lower temperatures by pressure.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 228 (1995), S. 179-184 
    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: Mit Hilfe der kontinuierlichen Polymerfraktionierung (CPF) wurden 45 g Poly(acrylsäure) (PAA 500) mit einer trimodalen Molmassenverteilung (M̄w = 500 kg/mol, (M̄w/M̄n) -1 = 2,33) in zwei Stufen mit 1,4-Dioxan als Lösungsmittel fraktioniert. Die Gegenstrom-Extraktion wurde in einer Glaskolonne (Länge: 190 cm, Durchmesser: 1,5 cm) durchgeführt, die mit einem Drahtnetzwerk gefüllt war, indem die Lösung 75 cm vom oberen Ende zugeführt wurde. Die Verteilung der Fraktion mit der höchsten Molmasse (M̄w = 760) ist unimodal und vergleichsweise eng ((M̄w/M̄n) -1 = 0,66). Es bestehen Anhaltspunkte, daß die Fraktionierung nicht nur in bezug auf die Molmasse, sondern auch in bezug auf die Taktizität erfolgt.
    Notes: 45 g of poly(acrylic acid) (PAA 500) with a trimodal molar mass distribution (M̄w = 500 kg/mol, (M̄w/M̄n) -1 = 2.33) were fractionated by means of CPF (continuous polymer fractionation) in two steps using 1,4-dioxane as solvent. The counter-current extraction was performed in a glass column (length: 190 cm, diameter: 1.5 cm) filled with a network of wires, introducing the feed 75 cm from its upper end. The distribution of the highest molar mass fraction (M̄w = 760 kg/mol) is unimodal and comparatively narrow ((M̄w/M̄n) -1 = 0.66). Indications exits that fractionation is not only taking place with respect to molar mass but also with respect to tacticity.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 161 (1988), S. 157-173 
    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: Poly(n-decylmethacrylat), ein statistisches Copolymeres aus Ethylen und Propylen, und ein Zweiblockcopolymeres aus Styrol und hydriertem Butadien wurden repräsentativ für verschiedene Arten von Viskositätsindex-Verbesserern untersucht. Essomarcol 52 und AF 1 von Schindler dienten als öle; Toluol und 1 Phenyldodecan wurden ebenfalls untersucht. Mit Hilfe von Viskositätsmessungen im Temperaturbereich von 37,8 bis 98,9°C und bis zu einer Polymerkonzentration von 1 Gew.-% wurden die Viskositätsindizes und die entsprechenden Grenzviskositätszahlen, Huggins-Koeffizienten sowie Fließ-Aktivierungsenergien, E≠, verschiedener Systeme bestimmt. Die Erörterung der experimentellen Ergebnisse zeigt, daß der Viskositätsindex von öl auf zwei unterschiedliche Arten erhöht werden kann: (i) durch Erhöhung der Viskosität aufgrund der blolßen Anwesenheit von Polymeren ohne Veränderung von E≠ und(ii), weniger häufig, durch Verringerung von E≠ als Folge der thermodynamischen Wechselwirkung. Es werden Gleichungen angegeben, die es erlauben, diese beiden Beitrlge zu berechnen .
    Notes: Poly(n-decyl methacrylate), a statistical copolymer of ethylene and propylene, and a diblock copolymer of styrene and hydrogenated butadiene were studied as representatives of various kinds of viscosity-index (VI) improvers. Essomarcol 52 and AF 1 from Schindler served as base-oils, toluene and 1-phenyl dodecane were also studied. By means of viscosity measurements in the temperature interval from 37.8 to 98.9°C up to a concentration of typically 1 wt.-% polymer, the viscosity indices of the different systems and the corresponding intrinsic viscosities, Huggins coefficients, and activation energies of flow, E≠, were determined. The discussion of the obtained experimental material demonstrates that the VI of a base-oil can be raised in two clearly distinguishable ways: (i) via an increase in the viscosity due to the mere presence of the polymer, without a change in E≠ and (ii), less general, via an additional reduction of E≠ as a consequence of thermodynamic interactions. Formulae are given from which these two contributions can be calculated.
    Additional Material: 10 Ill.
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  • 5
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Fragmentation Reactions of Carbonyl Compounds with Electronegative β-Substituents, XXXII: Reaction of 2,2-Dialkyl-1-cyclohexyl-3-tosyloxy-1-propanone with NucleophilesTosylates 6 and 12 are synthesized starting from ketones 4 and 10,6 and 12 react with CH3Li to yield the oxetanes 17 and 20. LiBH4 reduction of 6 and 12 leads to the oxetanes 16 and 19, as well as to the tosyloxy alcohols 21 and 22. The neopentyl substitution products 7 and 13 are obtained from 6 and 12 with KCN in DMSO, whereas from 6 the cyano oxetane 18 was isolated too. With potassium tert-butoxide 6 reacts to give the enol ether 23, whereas 12 leads to the cyclo-butanone 25. The triflate 14 react with NaOCH3 to give the substitution product 15.
    Notes: Ausgehend von den Ketonen 4 und 10 werden die Tosylate 6 und 12 dargestellt, die mit CH3Li zu den Oxetanen 17 bzw. 20 reagieren. LiBH4-Reduktion von 6 bzw. 12 führt zu den Oxetanen 16 bzw. 19. daneben werden die Tosyloxy-alkohole 21 bzw. 22 isoliert. setzt man 6 bzw. 12 mit KCN in DMSO um, so werden die Neopentylsubstitutionsprodukte 7 bzw. 13, daneben aus 6 auch das Cyan-oxetan 18 erhalten. Mit Kalium-tert-butylalkoholat erhält man aus 6 den Enol-äther 23, dagegen aus 12 das Cyclobutanon 25. Das Triflat 14 reagiert mit NaOCH3 unter Substitution zu 15.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 197 (1996), S. 2961-2972 
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Cloud point curves were measured turbidimetrically for blends (upper critical solution temperatures; UCSTs) of poly(ethylmethylsiloxane) (PEMS) and four different samples of poly(dimethylsiloxane) (PDMS); the weight average molar masses in kg/mol are 31.2 for PEMS and 10.4, 15.5, 18.1 and 24.0 for PDMS; all components have polydispersity indices D (= M̄w/M̄n) within the range from 1.82 to 2.67. Corresponding calculations on the basis of the Flory-Huggins theory (three adjustable parameters) account for the poly-dispersity; molecular weight distributions are represented by the generalized Schulz-Flory equation. Calculated cloud point curves agree very well with those measured, if individual sets of parameters are admitted for each of the different mixtures. Even for an identical set of parameters the maximum deviations remain moderate. Realistic model calculations concerning the influences of D on cloud points and on critical points were performed with this set of parameters. For the present (only slightly endothermal) system, the precipitation threshold increases from 318 to 558.6 K as DPEMS is raised from 1.87 to 4.00, keeping the number average degree of polymerization constant.
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  • 7
    Electronic Resource
    Electronic Resource
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 6 (1985), S. 21-27 
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 4 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 1 (1980), S. 231-234 
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 3 (1982), S. 17-21 
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 4 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 8 (1987), S. 461-466 
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
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