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  • Polymer and Materials Science  (92)
  • lattice distortions  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cellulose 2 (1995), S. 51-70 
    ISSN: 1572-882X
    Keywords: X-ray scattering ; crystallite dimensions ; lattice distortions ; microfibrils ; manmade fibres ; native cellulose ; alkalization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract This paper gives an overview of our recent research activities on the lateral supramolecular order of a variety of native and man-made cellulosics considering respective results from the literature. Wide-angle X-ray scattering (WAXS) was the main investigation technique used. Lateral root mean squared lattice strains between 2 and 3% were determined for the materials investigated. Crystallite sizes obtained without considering lattice distortions usually do not deviate by much more than −10% from the real, i.e. fully corrected values. This means that it is sufficient to use the simple Scherrer equation for determining lateral crystallite sizes for most routine investigations of cellulosic materials. The possible superposition of WAXS peaks of the triclinic Iα and monoclinic Iβ lattice types, however, has to be considered in crystallite size determinations for Valonia cellulose. It could be shown that neglecting this fact can lead to crystallite sizes being about 20% below the true ones. Lateral crystallite dimaensions for native celluloses vary between 4nm (dissolving pulps) and 10-15 nm (Valonia). Except for bacterial cellulose, the WAXS crystallite sizes are distinctly smaller than the microfibril dimensions obtained from electron microscopy. The man-made fibres investigated showed lateral crystallite dimensions between 3 and 5nm. The importance of lateral crystallite dimensions for the properties of man-made fibres and for the alkalization process of native cellulose id demonstrated.
    Type of Medium: Electronic Resource
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  • 2
    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 effect of the charge density on the composition of symplex precipitates was investigated using a series of cationically modified polyacrylamides and poly(dimethyl-diallyl-ammonium chloride) as cationic component and two carboxymethyl celluloses with different degree of substitution, cellulose sulfate and two maleic acid copolymers as anionic component. The formation of 1:1 symplexes is obviously possible even at considerable differences of the average charge distance of the constituting components if the mobility of the charge centres is sufficient.
    Notes: Der Einfluß der Ladungsdichte auf die Zusammensetzung von Symplexfällungen wurde unter Verwendung einer Serie kationisch modifizierter Polyacrylamide bzw. von Poly(dimethyl-diallyl-ammoniumchlorid) als kationischer Komponente, von unterschiedlich hoch substituierten Carboxyethylcellulosen sowie von Cellulosesulfat und von zwei Maleinsäurecopolymeren als anionischer Komponente untersucht. Die Bildung von 1:1-Symplexen ist offensichtlich auch bei erheblichen Unterschieden im mittleren Ladungsabstand für die beteiligten Komponenten möglich, wenn die Ladungszentren eine ausreichende Beweglichkeit aufweisen.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 31 (1980), S. 662-667 
    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 effect of preactivation of beech sulfite pulp by liquid ammonia on the solubility of carboxymethylcellulose at DS values between 0.3 and 0.4 has been investigated. No essential effect was found with purely aqueous reaction systems. By using an ethanol/water mixture as reaction medium the preactivation resulted in a distinct decrease of the insoluble residue of the reaction product.
    Notes: Es wurde geprüft, inwieweit die Löslichkeit von Carboxymethylcellulosen bei DS-Werten zwischen 0,3 und 0,4 durch eine Voraktivierung des eingesetzten Buchensulfitzellstoffs mit flüssigem Ammoniak beeinflußt werden kann. Bei Verwendung rein wäßriger Reaktionssysteme wurde kein wesentlicher Einfluß der Voraktivierung gefunden. Bei Verwendung eines Ethanol/Wasser-Gemisches als Reaktionsmedium führte eine Voraktivierung zu einer deutlichen Verminderung des unlöslichen Rückstandes beim Reaktionsprodukt.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 32 (1981), S. 730-732 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: No Abstracts.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 30 (1979), S. 229-230 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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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: Based on various principles of preparing cellulose particles for ion exchangers a technique of preparation of spheric cellulose particles having narrow pore size distribution is described. With respect to the morphological parameters the properties of the pearl cellulose thus obtained are characterized. Various possibilities of subsequent modification of the chemical and morphological structure are considered. With some selected examples the large field of possible application of pearl cellulose is outlined.
    Notes: Ausgehend von den verschiedenen Prinzipien zur Herstellung von Cellulosepartikeln für Ionenaustauscher wird ein Verfahrensweg zur Herstellung von kugelförmigen Cellulosepartikeln mit enger Größenverteilung beschrieben. Unter Betonung morphologischer Parameter wird das Eigenschaftsbild der so erhaltenen Perlcellulosen dargestellt. Über die verschiedenen Möglichkeiten einer nachträglichen Modifizierung der chemischen und morphologischen Struktur dieser Produkte wird berichtet. Abschließend wird anhand einiger ausgewählter Beispiele die breite Palette der Einsatzmöglichkeiten von Perlcellulose umrissen.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 34 (1983), S. 105-108 
    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: 13C-NMR investigations were performed with cellobiose and two cellulose samples characterized by DP 35 and 285 in the mixed solvents N-methylmorpholine-N-oxide, dimethylsulfoxide/paraformaldehyde and calcium rhodanide/formaldehyde/water. In the calcium rhodanide/formaldehyde/water mixture, similar as in paraformaldehyde/DMSO, the methylation proceeds preferentially at the C6 atom, while no specific interaction was observed between the rhodanide ion and cellulose. In all mixed solvents investigated a signal, not having been described before, was observed in the 87 to 90 ppm range. The assignment is discussed with respect to formaldehyde-containing systems.
    Notes: 13C-NMR-spektroskopische Untersuchungen wurden an Cellobiose und an zwei Celluloseproben mit DP 35 und DP 285 in den Lösungsmittelsystemen N-Methylmorpholin/N-oxid, Dimethylsulfoxid/Paraformaldehyd und Calciumrhodanid/Formaldehyd/Wasser durchgeführt. Im Calciumrhodanid/Formaldehyd/Wasser-System erfolgt ähnlich wie im Paraformaldehyd/DMSO-System eine Methylolierung bevorzugt am C-Atom 6, während zwischen Rhodanidion und Cellulose offenbar keine spezifischen Wechselwirkungen auftreten. In allen drei Lösemittelsystemen wird ein bisher nicht beschriebenes Signal im Bereich zwischen 87 und 90 ppm beobachtet; Möglichkeiten einer Deutung werden für die formaldehydhaltigen Systeme diskutiert.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 31 (1980), S. 388-393 
    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 effect of mercerisation and the state of swelling on amount and DP of residues in enzymatic degradation of linters cellulose by the enzyme system of Gliocladium spec. has been investigated. The time-dependence of the amount of residues can be described by a first order equation while the DP of residues passes a minimum value as the time of degradation increases. The effect of crystalline modification (cellulose I or II) on the degradation process is obviously smaller than the effect of the state of swelling (water retention value).
    Notes: Der Einfluß von Quellungszustand und Mercerisierung auf Rückstandsmenge und Rückstands-DP beim enzymatischen Abbau von Linterscellulose durch das Enzymsystem von Gliocladium spec. wurde untersucht. Der zeitliche Verlauf der Rückstandsmenge ließ sich durch ein Zeitgesetz 1. Ordnung beschreiben, während der Rückstands-DP mit fortschreitender Abbauzeit ein Minimum durchlief. Gegenüber dem entscheidenden Einfluß des Quellungszustandes (WRV-Wert) tritt der Einfluß des Gittertyps (Cellulose I bzw. Cellulose II) auf den Abbauverlauf offensichtlich zurück.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 32 (1981), S. 225-226 
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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