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  • 1
    Electronic Resource
    Electronic Resource
    Effect of tensides on gas production in an anaerobic filter (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 21 (1979), S. 333-336 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260210218
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  • 2
    Electronic Resource
    Electronic Resource
    Kinetische und morphologische untersuchungen zur polymerisation von oxacyclischen monomeren im festen zustand, 2.Teil 1: cf. Makromol. Chem. 179, 219 (1978). Zur morphologie der bei der straheleninduzierten polymerisation von trioxan und tetroxan entstehenden poly(oxymethylene) (1978)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 1083-1105 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In order to clarify the reaction mechanism of the solid-state polymerisation of 1,3,5-trioxane and 1,3,5,7-tetroxane as induced by gamma-radiation, the nascent textures and morphology of poly(oxymethylene) crystals were studied with light and transmission electron microscopy, X-ray scattering and differential thermal analysis techniques. In both cases poly(oxymethylene) crystals with fibrous morphology and “twin-structure” are obtained. The polymerization of 1,3,5,7-tetroxane gives rise to the formation of crystals where the preferred orientation of the polymer chain is the monomer b-axis; however, the fibrils showed ripples perpendicular to the main chain direction at a 70-240Å long period that depends extremely on the polymerization temperature. In the polymerization of 1,3,5-trioxane, POM crystals with 60% of the polymer chains in the direction of the monomer c-axis are obtained. The remaining chains are found in the “twin sub-crystals”. Dark field electron micrographs showed the sub-crystals to be an integral part of the fibrils. The material in the twin direction decreases, when the polymerization temperature or the yields increases; it never amounts to less than 30%. These results and the misfit between the lattices of the monomers and the nascent polymer indicate that the reactions which take place occur according to a simultaneous polymerization and crystallization mechanism through the gasphase. The polymerization process occurs easier at higher temperatures near the monomers' melting point due to the increase of monomer vapor pressure and diffusion processes in the monomer crystals. Molecular models of the chain growth are developed on the basis of the morphological observations.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1978.021790422
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  • 3
    Electronic Resource
    Electronic Resource
    Kinetische und morphologische Untersuchungen zur polymerisation von oxacyclischen Monomeren im festen Zustand, 1. Zur Morphologie der bei der Polymerisation von 1,3,5,7-Tetroxocan mittels chemischer Katalysatoren entstehenden Polyoxymethylene (1978)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 219-230 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In order to elucidate the reaction mechanism of the chemically induced solid-state polymerization of 1,3,5,7-tetroxocane, the nascent morphology of poly(oxymethylene), (POM) crystals was investigated. The results show that POM has a lamellar morphology consisting of folded polymer chains. This morphology is different from that of the fibrous morphology obtained by radiation induced solid-state polymerization of 1,3,5,7-tetroxocane. Based on this the reaction takes place according to a crystallization succeeding polymerization mechanism, where the monomer passes through the gasphase to reach the reaction center.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1978.021790122
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  • 4
    Electronic Resource
    Electronic Resource
    Kinetische und morphologische untersuchungen zur polymerisation von oxacyclischen monomeren im festen zustand, 3.Teil 2: cf.17. Zur morphologie der bei der polymerisation von trioxan mit chemischen katalysatoren entstehenden polyoxymethylene (1978)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 2515-2529 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The nascent crystal structure and morphology of poly(oxymethylene) (POM) obtained from 1,3,5-trioxane crystals, induced by gaseous chemical initiators, was studied in order to clarify the solid-state polymerization mechanisms of this monomer. The polymerization starts at the surface of the monomer crystals and propagates towards its interior. The polymerization rate, therefore, depends on the size of the crystals and not on the initiator amount. Hexagonal fibrous crystals without a main orientation were obtained on the surface of the monomer crystal. These crystals orientated themselves along the c-axis of the monomer, due to the polymerization propagation inside the crystals by simultaneous solid-gas polymerization and crystallization mechanisms. The orientation depended on the reactivity of the initiator, the order being: BF3-O(C2H5)2 〉 SnCl4 〉 H2SO4-paraformaldehyde. The orientation was also improved by increasing the polymerization temperature, obtaining POM crystals similar to those found by radiation induced polymerization. At low polymerization temperature folded chain crystals were obtained similar to those encountered by solution polymerization according to crystallization succeeding polymerization mechanisms.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1978.021791016
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  • 5
    Electronic Resource
    Electronic Resource
    Crystal structure and morphology of polymers from solid-state reactionsDedicated to Professor Dr. H. Mark on the occasion of his 80th birthday (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 521-558 
    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: Einige Festkörperrcaktionen. die zur Bildung von Polymer-Kristallen führen. werden diskutiert und es wird gezeigt, wie man die Ergebnisse der morphologischen Untersuchungen dazu verwenden kann, den Mechanismus der Festkörperpolymerisation aufzuklären. Beispiele für die folgenden drei Mechanismen werden im einzelnen behandelt: (a) Kristallisation der makromolckularen Ketten nach der Polymerisation, (b) simultane Polymerisation und Kristallisation, (c) Polymerisation in fester Lösung.Als ein Beispiel für Kristallisation nach bereits erfolgter Polymerisation wird die Morphologie von Ziegler-Natta Olefin-Polymerisaten diskutiert. Ein anderes Beispiel dafür liefert die kationische Polymerisation von 1,3,5-Trioxan aus Lösungen. Es wird gezeigt. daß in diesem Fall das System einem thermodynamischen Gleichgewicht zwischen der kristallinen Phase des Polymeren und dem gelösten Monomeren zustrebt. Dabei findet durch Aufbrechen der Kettenfalten und Einbau von Monomereinheiten ein Dickenwachstum der Kristalle statt, das schließlich zur Entstehung von gestrecktkettigen Kristallen durch diese Transacctalisierung führt.Die durch Bestrahlung oder katalytisch induzierte Festkörperpolymerisation von 1,3,5-Trioxan oder 1,3,5,7-Tetroxan stellt ein Beispiel für simultane Polymerisation und Kristallisation dar. Einige molekulare Modelle für das Wachstum der Ketten werden auf Grund der morphologischen Beobachtung entwickelt. Es zeigt sich, daß bei diesen Reaktionen im allgemeinen keine wirklichen gestrecktkettigen Kristalle des Poly(oxymethylen)s. (POM) entstehen; Ursache dafür ist entweder Kettenfaltung (Dichtefluktuation entlang der Faserachse) oder Zwillingsbildung (Orienticrungsfluktuation). Art und Ursprung der Zwillingsbildung von POM aus kristallinem 1,3,5-Trioxan wird im einzelnen erörtert.Die topochemische Polymerisation von Monomeren mit konjugierten Dreifachbindungen gibt ein Beispiel für Polymerisation in fester Lösung. Die Polymerketten wachsen als isolierte Einheiten im Gitter des Monomeren. In einigen Fällen kann das gesamte Monornere ohne Phasentrennung umgesetzt werden. Dadurch entstehen makroskopische Polymer-Einkristalle aus gestreckten Ketten. die bisher noch nicht auf andere Weise dargestellt werden konnten.
    Notes: Some solid-state reactions which give rise to the formation of polymer crystals are discussed and the observation of the nascent polymer morphology is used as a guide-line to learn about the reaction mechanism of solid-state polymerizations. Examples for the following three different mechanisms are treated in detail: (a) crystallization succeeding polymerization, (b) simultaneous polymerization and crystallization, and (c) polymerization in solid solution.The nascent morphology of poly(alkylene)s obtained by Ziegler-Natta catalysis is taken as an example for crystallization succeeding polymerization. Another example is the cationic polymerization of 1,3,5-trioxane from solution. In this case a thermodynamic equilibrium between the phases of the solid crystalline polymer and the dissolved monomer is approached; here, by breaking up chain folds and insertion of monomeric units, an increase in thickness of the crystals takes place, which finally leads to extended chain crystals by this transacetalization.The solid-state polymerization of 1,3,5-trioxane and 1,3,5,7-tetroxane as induced by high-energy radiation or catalysts is described as an example for simultaneous polymerization and crystallization. Possible molecular models of the chain growth are developed on the basis of the morphological observations. Truly extended chain crystals of poly(oxymethylene), (POM), cannot be obtained generally from solid 1,3,5-trioxane or 1,3,5,7-tetroxane; the reason for this is either chain-folding (density fluctuation along the fibre axis) or “twin”-structure formation (orientation fluctuation). The nature and origin of the “twin”-structure of POM from crystalline 1,3,5-trioxane is discussed in detail.Topochemical polymerization of monomers with conjugated triple-bonds is an example for polymerization in solid solution. The polymer chains grow as isolated macromolecules within the monomer lattice. Since quantitative conversion can be reached in some cases without phase separation, this comprises a method to produce macroscopic, extended chain polymer single crystals, which so far could not be prepared by another method.
    Additional Material: 28 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.020011975136
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  • 6
    Electronic Resource
    Electronic Resource
    Solution polymerization of 1,3,5-trioxane and 1,3,5,7-tetroxocane, 1. Rate of polymerization, characterization and melting behaviour of as-polymerized poly(oxymethylene) (1976)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 177 (1976), S. 2149-2168 
    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: Die Beziehung zwischen Polymerisationsgeschwindigkeit und Struktur der während der Polymerisation entstehenden Polymerkristalle wurde für die kationische Polymerisation von 1,3,5-Trioxan und 1,3,5,7-Tetroxocan („Tetroxan“) in Lösung untersucht. Es wurden folgende Monomer/Lösungsmittel Paare gewählt : Tetroxan/Nitrobenzol (I), Tetroxan/l,2-Dichloräthan (II), 1,3,5-Trioxan/chloriertes Paraffin (III) und 1,3,5-Trioxan/n-Paraffin (IV). Das in allen Fällen hergestellte Poly(oxymethylen), (POM), wurde nach Molekulargewicht, Röntgenkristallinität und dem Schmelzverhalten mit Hilfe der Differentialkalorimetrie, (DSC), charakterisiert. Für die Systeme I und II, wo die Polymerisationsgeschwindigkeit sehr groß war, wurde auf Grund der mit DSC erhaltenen Ergebnisse eine aus gefalteten Ketten bestehende Struktur gefunden. Bei höherem Umsatz im System II weist das Schmelzverhalten von POM jedoch auf eine gestreckt-kettige Struktur hin. Für die Systeme III und IV, wo die Polymerisationsgeschwindigkeit sehr langsam verläuft, kann aus den DSC-Ergebnissen in beiden Systemen aufzwei Kristallstrukturen geschlossen werden. Eine davon kann auf Grund der Überhitzungserscheinungen und auf Grund von Tempereffekten gestreckt-kettiges POM darstellen. Die andere Kristallstruktur zeigt kein eindeutiges Schmelzverhalten, weshalb aus den DSC-Ergebnissen allein die Struktur nicht zu bestimmen ist.
    Notes: A relationship between the rate of polymerization and the structure of the as-polymerized crystals is investigated in the cationic polymerization in solution of 1,3,5-trioxane and 1,3,5,7-tetroxocane. The monomer/solvent reaction systems chosen were: 1,3,5,7-tetroxocane/nitrobenzene (I); 1,3,5,7-tetroxocane/l,2-dichloroethane (II), 1,3,5-trioxane/chlorinated parafin (III), and 1,3,5,7-trioxane/normal paraffin (IV). The poly(oxymethylene), (POM), obtained in each case was characterized as to molecular weight, X-ray cristallinity and by differential scanning calorimetry (DSC). The data from the DSC curves indicated a folded chain structure for systems I and II, where the rate pf polymerization was very high. However in system II at high polymer conversion a fraction of POM appears with a melting behaviour characteristic of an extended chain structure. For systems III and IV, where the rate of polymerization was very low, the DSC curves indicated the presence of two crystal forms. One of these forms shows a clear response to overheating and annealing treatments, which indicates the presence of an extended chain structure. The second form shows ambiguous melting behaviour and by thermal data alone it is impossible to determine its structure.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1976.021770719
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  • 7
    Electronic Resource
    Electronic Resource
    Solution polymerization of 1,3,5-trioxane and 1,3,5,7-tetroxocane, 2.Part 1: cf.3. Morphology of the as-polymerized poly(oxymethylene) crystals (1976)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 177 (1976), S. 2169-2184 
    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: Die Morphologie von Poly(oxymethylen), (POM), Kristallen, die aus verschiedenen Monomer/Lösungsmittel Polymerisationsystemen hergestellt worden waren, wurden mittels Elektronenmikroskopie untersucht. Die aus 1,3,5,7-Tetroxocan („Tetroxan“) in Nitrobenzol entstehenden POM Kristalle zeigen eine lamellare Morphologie mit undefinierter hexagonaler Form. Andererseits wurden neue rhombische POM Kristalle bei der Polymerisation von Tetroxan in 1,2-Dichloräthan erhalten. Beide Kristallarten zeigen wahrscheinlich eine Struktur mit gefalteten Ketten. Federartige Kristalle mit seitlich fibrillärem Wachstum wurden bei der Polymerisation von 1,3,5-Trioxan in n-Paraffin gefunden. Eine große Zahl von Kristallen verschiedener Morphologien wurde bei der Polymerisation von 1,3,5-Trioxan in chloriertem Parafin erhalten, die in zwei hauptsächliche Gruppen eingeteilt werden können: Eine Gruppe besteht aus veränderten federartigen Kristallen, während die andere mehr geometrisch dreieckige und rhombisch geformte Plättchen umfaßt. Alle diese Kristalle zeigen seitliches fibrilläres Wachstum, so daß am Ende der Polymerisation eine übenviegend fibrilläre Morphologie zu beobachten ist. Es wird angenommen, daß alle diese Kristalle eine gestrecktkettige Struktur aufweisen.
    Notes: The morphology of poly(oxymethylene), (POM), crystals obtained from different monomer/solvent polymerization systems was studied by means of electron microscope techniques. POM obtained from 1,3,5,7-tetroxocane in nitrobenzene had an irregular hexagonoidal shaped lamellar morphology, while rhombic POM crystals were obtained from the polymerization of 1,3,5,7-tetroxocane in 1,2-dichloroethane. Both types of crystals probably have a folded chain structure. POM obtained from 1,3,5-trioxane in normal (unbranched) paraffin represented the feather-like crystals with proliferating lateral growths. POM obtained from 1,3,5-trioxane in chlorinated paraffin presented numerous crystals of different morphologies. Two main groups could be discerned: one consisted of variations of the basic feather-like crystal, while the other comprised more geometrically triangular and orthorhombic morphologies. All these crystals presented lateral growths, and toward the end of the polymerization a fibrous morphology prevailed. Evidence points to their being crystals of an extended chain structure.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1976.021770720
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis of polystyrene containing transition metals (1977)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 178 (1977), S. 659-667 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The synthesis of styrene polymers containing transition metals was achieved by reaction of different polystyrenes with Mt(CO)6 or (CH3—C≡N)3Mt(CO)3, (Mt = Cr, Mo, or W). Atactic, isotactic, and cross-linked polystyrene (with divinylbenzene) were employed. Organometallic polymers with good stability were only obtained by coordination of tricarbonylchromium groups to the phenyl rings of the polystyrene. Tricarbonylmolybdenum- and tricarbonyltungsten complexed polystyrene showed very poor stability and could not be isolated. The amount of chromium incorporated depends on the molecular structure of the polymers, the chromiumcarbonyl complex used in the reaction, and the reaction time. The reactivity of the tris(acetonitrile)tricarbonylmetal-complexes is higher than that of the hexacarbonylmetal-complexes and the addition reactivity of the polymers is in the order: atactic 〉 isotactic 〉 cross-linked polystyrene
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1977.021780303
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  • 9
    Electronic Resource
    Electronic Resource
    Kinetische und morphologische untersuchungen zur polymerisation von oxacyclischen monomeren im festen zustand, 5Teil 4: A. Muñoz-Escalona, G. Wegner, Makromol. Chem. 149, 197 (1971).. Zur morphologie der während der sublimation von trioxan- und tetroxankristallen wachsenden polyoxymethylene (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 713-720 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The polymerization and crystallization of polyoxymethylene obtained by sublimation of trioxane (1,3,5-trioxane) and tetroxane (1,3,5,7-tetroxocane) crystals was investigated. Electron microscopy techniques and thermal analysis were used to characterize the polymer crystals as produced and after annealing. The polyoxymethylene crystals resulting from tetroxane show a regular lamellar folded chain macroconformation similar to those previously reported by polymerization of tetroxane crystals chemically initiated. The polymerization follows a crystallization succeeding polymerization mechanism. Trioxane gives mainly fibrous crystals, showing well oriented electron diffraction diagrams and higher melting points, consisting mostly of extended chains. A “pseudolamellar” morphology was also observed, being established by annealing, that the chain directions are parallel to the edges of the crystals. The strange growing habit seems to be produced by disruption of the electrical field of the trioxane crystals by a water effect. The polymerization seems to follow mainly a simultaneous polymerization and crystallization mechanism. The initiation of the polymerization is in both cases due to the gaseous formaldehyde formed during sublimation.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.021800315
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