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  • Polymer and Materials Science  (19)
  • segmented liquid crystalline polyure-thanes  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Segmented polyurethanes with 4,4′-bis-(6-hydroxyhexoxy)biphenyl as chain extender. Part 2. Synthesis and properties of MDI-polyurethanes in comparison with 2,4-TDI-polyurethanes (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 34 (1996), S. 33-44 
    Details
    ISSN: 0887-624X
    Keywords: main-chain liquid crystal polymers ; segmented liquid crystal polymers ; synthesis ; characterization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Linear segmented polyurethanes based on poly(butylene adipate)s (PBA) of different molecular weight (Mn 2000, 1000, and 600), 4,4′-diphenylmethane diisocyanate (MDI) and the mesogenic diol 4,4′-bis-(6-hydroxyhexoxy)biphenyl (BHHBP) as well as the unsegmented polyurethane consisting of MDI/BHHBP units have been synthesized and characterized by elemental analysis, 13C-NMR and SEC. The thermal behavior and the morphology were studied by DSC, polarizing microscopy, and DMA. The properties of the MDI-polyurethanes were discussed in relation to the BHHBP chain extended 2,4-TDI-polyurethanes and common 1,4-butanediol chain-extended MDI products. MDI polyurethanes based on PBA (Mn 2000) exhibit a glass transition temperature Tg of about -40°C independent of the hard segment content up to ∼50% hard segments. At higher hard segment contents increasing Tgs were observed. Polyurethanes, based on the shorter polyester soft segments PBA (Mn 1000 or 600), reveal an increase in the glass transition temperatures with growing hard segment content. The thermal transitions caused by melting of the MDI/BHHBP hard segment domains are found at 50 K higher temperatures in comparison with the analogous TDI products with mesogenic BHHBP/TDI hard segments. Shortening of the PBA chain length causes a shift of the thermal transitions to lower temperatures. Polarizing microscopy experiments indicate that liquid crystalline behavior is influenced by both the content of mesogenic hard segments and the chain length of the polyester. © 1996 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Segmented polyurethanes with 4,4′-bis-(6-hydroxyhexoxy) biphenyl as chain extender. I. Synthesis and characterization of 2,4-tdi-polyurethanes (1995)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 33 (1995), S. 1523-1536 
    Details
    ISSN: 0887-624X
    Keywords: main-chain liquid crystalline polymers ; segmented liquid crystalline polyure-thanes ; synthesis ; characterization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Polyurethanes composed of 2,4-toluene diisocyanate (TDI), poly (butylene adipate) diols (PBA) of different molecular weights, and 4,4′-bis-(6-hydroxyhexoxy) biphenyl (BHHBP) were prepared by a two-step solution polymerization process. The polyurethanes were char-acterized by elemental analysis, NMR, and SEC. The thermal properties were investigated by DSC, DMA, and optical polarizing microscopy. Dependent on the molecular weight of the PBA, a shift in the glass transition temperature Tg of the polyurethanes has been observed by DSC and DMA. Polyurethanes based on poly (butylene adipate)s of Mn ∼ 2000 exhibited a Tg nearly independent on the hard-segment content up to 50% LC hard segments, indicating the existence of mainly phase separated soft and hard segments. By shortening the PBA chain length up to 1,000 and further to 600, the Tg of the polyester soft-segment phase increases with growing hard-segment content, a consequence of enhanced interaction between the hard and soft segments. This tendency is observed to the greatest extent at polyurethanes with the shortest, polyester diol and can be interpreted as a partial miscibility or compatibility of hard and soft segments. Although in polyurethanes with PBA 2000 the mesophase can be proven at a hard-segment content of ∼ 40%, its appearance in polyure-thances prepared with PBA 1000 or PBA 600 requires a hard-segment content 〉 60%. © 1995 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1995.080330914
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  • 3
    Electronic Resource
    Electronic Resource
    Untersuchungen zur Plasmaätzung von Polymeren. IV. Selektives Plasmaätzen von Polyethylenen unterschiedlicher KristallinitätTeil III: Acta Polymerica 31 (1980) 59-62 (1980)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 31 (1980), S. 310-315 
    Details
    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: Polyethylenes of different crystallinity and crosslinking were etched plasmachemically for revealing supermolecular structures. Electron microscopic patterns of the etched polymer surfaces show differences in the degree of crystallinity up to 3%.
    Notes: Polyethylenproben unterschiedlicher Kristallinität und Vernetzung wurden zur Freilegung übermolekularer Strukturen plasmachemisch geätzt. Die elektronemikroskopischen Aufnahmen der geätzten Polymeroberflächen zeigten, daß sich Unterschiede im Kristallinitätsgrad bis zu 3% im Ätzrelief widerspiegeln.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1980.010310506
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  • 4
    Electronic Resource
    Electronic Resource
    Untersuchungen zur Plasmaätzung von Polymeren. VI. Veränderungen an der Oberfläche von PolypropylenTeil V: Acta Polymerica 32 (1981) 48 (1981)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 32 (1981), S. 337-343 
    Details
    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: As detected by photoelectron spectroscopy (ESCA) no saturation in concentration of N-containing groups occurs on the surface of polypropylene up to 50 minutes exposition in NH3 plasma. Under the particular conditions of the plasma the presence of amino groups is suggested. No large changes in structure of layers under the surface (up to 100 μm) were observed. The surface was roughed strongly by O2 plasma treatment. The etching patterns correspond to those of a predominantly monoaxialy stretched polymer.
    Notes: Bei der Behandlung von Polypropylenfolien im NH3-Plasma trat nach photoelektronenspektroskopischen Untersuchungen bis mindestens 50 min Behandlungszeit keine Sättigung der Konzentration an N-haltigen funktionellen Gruppen an der Polymeroberfläche ein. Bei den speziell gewählten Plasmabedingungen kann auf das Vorliegen von NH2-Gruppen geschlossen werden. Strukturelle Veränderungen in tieferliegenden Schichten traten kaum auf. Durch O2-Plasmabehandlung wurde die Folienoberfläche stark aufgerauht. Die Ätztruktur entsprach einem überwiegend monoaxial gereckten Polymer.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1981.010320609
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  • 5
    Electronic Resource
    Electronic Resource
    Untersuchungen zum Einfluß einer Oberflächenmodifizierung von Fasermaterialien im nichtthermischen Plasma einer Hochfrequenz-Entladung auf die Adhäsionsfestigkeit zu Epoxidharz. Teil III: Ergebnisse der Behandlung von Kohlenstoff-Fasern im NH3-PlasmaTeil II: siehe [6] (1983)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 34 (1983), S. 171-177 
    Details
    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: Carbon fibres were modified by different N containing groups at the surface in a nonthermal NH3-plasma. This was estimated by means of photoelectron spectroscopy. During the plasma exposition a layer of low molecular hydrogenated products formed at the surface. By plasma exposition the wetting of fibres with epoxy resin was increased.
    Notes: Kohlenstoff-Fasern wurden in einem nichtthermischen NH3-Plasma an der Oberfläche mit verschiedenartigen Nhaltigen Gruppen funktionalisiert, was mit Hilfe der Photoelektronenspektroskopie nachgewiesen wurde. Im Verlaufe der Plasmabehandlung entstand an der Faseroberfläche eine Schicht niedermolekularer, hydrierter Produkte. Die Benetzung der Fasern mit Epoxidharz wurde durch die Plasmabehandlung verbessert.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1983.010340311
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  • 6
    Electronic Resource
    Electronic Resource
    Röntgen-photoelektronenspektroskopische Untersuchungen zur Ermittlung der Schwachstelle in Polyamid-6/Silan/Glas-Verbundmodellen (1983)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 34 (1983), S. 260-264 
    Details
    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: Both sides of interfaces were investigated by XPS after peeling polyamide 6 off the glassy substrates. The fracture was found to proceed through the polymer and the weak boundary layer, consisting of γ-mercaptosilane and PA-6, between polymer and glass. The influence of γ-mercaptopropyltrimethoxysilane on the shear strength was examined and interpreted as complex result of several factors acting against one another.
    Notes: Röntgen-photoelektronenspektroskopische Untersuchungen der Trennflächen von Glas/Polyamid-Verbunden zeigten, daß die Bruchfläche teilweise durch das Polymer und durch eine schwache Zwischenschicht, die aus dem γ-Mercaptosilan und dem Polyamid-6 besteht, verläuft. Der Einfluß des γ-Mercaptopropyltrimethoxysilans auf die Scherfestigkeit wurde untersucht und als komplexe Wirkung mehrerer gegenläufig wirkender Faktoren interpretiert.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1983.010340504
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  • 7
    Electronic Resource
    Electronic Resource
    Untersuchungen zur Plasmaätzung von Polymeren. Teil II. Einfluß der Plasmaparameter auf die Abbaugeschwindigkeit und die Freilegung übermolekularer PolymerstrukturenTeil I siehe [10] (1980)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 31 (1980), S. 52-58 
    Details
    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: An unmodified uncovering of structural inhomogeneities in polymers depends essentially on the selectivity of plasma etching by which weakly bound regions can be etched off. To a certain degree the selectivity of degradation can be controlled by plasma parameters. Further, the structural changes caused by plasma UV radiation (crosslinking, formation of radicals and double bonds) can be reduced by appropriate etching techniques. Considering these facts the plasma etching method can be applied for preparing highly characteristic etching patterns of the polymer structure.
    Notes: Eine wirklichkeitsgetreue Freilegung von Strukturinhomogenitäten in Polymeren hängt stark von der Selektivität der Plasmaätzung ab, mit der schwächer gebundene Polymerbereiche herausgeätzt werden können. In gewissem Umfang kann durch die Wahl der Plasmaparameter die Selektivität des Abbaus gesteuert werden. In gleicher Weise lassen sich auch die strukturverändernden Wirkungen der Plasma-UV-Strahlung (Vernetzung, Radikalbildung, Bildung von Doppelbindungen usw.) durch geeignete Ätzbedingungen verringern. Bei Beachtung dieser Gesichtspunkte liefert die Plasmaätzmethode sehr charakteristische Ätzreliefs der Polymerstruktur.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1980.010310110
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  • 8
    Electronic Resource
    Electronic Resource
    Untersuchungen zum Einfluß einer Oberflächenmodifizierung von Fasermaterialien im nichtthermischen Plasma einer Hochfrequenz-Entladung auf die Adhäsionsfestigkeit zu Epoxidharz. Teil II. Veränderungen der Struktur von Glasfasern nach PlasmabehandlungTeil I: siehe [1] (1981)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 32 (1981), S. 36-40 
    Details
    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: Fibres of boron-silicate-glass are destructed at the surface by ion bombardment from plasma of a radio-frequency glow discharge. The alkaline elements are sputtered away, but partly readsorbed as hydroxides. The strength of fibres decreases strongly on shorttime of plasma exposition. In a plasma of ammonia N-containing groups are formed on the surface of fibres.
    Notes: Borsilicatglasfasern werden durch den Beschuß mit Ionen aus dem Plasma einer Hochfrequenz-Glimmentladung oberflächlich umstrukturiert. Die Alkalielemente werden bevorzugt herausgesputtert und z. T. in Hydroxidform wieder abgelagert. Die Fasern verlieren auch nach nur kurzer Plasmabehandlungszeit stark an Eigenfestigkeit. Bei Behandlung im NH3-Plasma bilden sich an der Faseroberfläche N-haltige funktionelle Gruppen.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1981.010320109
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  • 9
    Electronic Resource
    Electronic Resource
    Untersuchungen zur Plasmaäzung von Polymeren. Teil III. Plasmamodifizierung von Polymeroberflächen zur Verbesserung der Hafteigenschaften der PolymereTeil II siehe [8] (1980)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 31 (1980), S. 59-62 
    Details
    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: Surface modification as well as nickel-plating using nickel tetracarbonyl in the plasma result in excellent adherence between polymers and copper surface coatings. Roughening the surface combined with chemical and structural changes as well as the formation of functional groups depending on the etching gas at the surface are suggested to cause the amelioration of adherence.
    Notes: Sowohl die Oberflächemodifizierung als auch die Vernickelung über Nickelteracarbonyl im Plasma führten jeweils zu ausgezeichneten Haftfestigkeitswerten zwischen Polymer und Kupferdeckschichten. Oberflächenaufrauhung, chemische und strukturelle Änderungen des Polymergefüges an der Oberfläche und die Schaffung ätzgasspezifischer funktioneller Oberflächengruppen werden als Ursache der Verbesserung der Hafteigenschaften angesehen.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1980.010310111
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  • 10
    Electronic Resource
    Electronic Resource
    Imprägnierung von Papieren mit Phenolharzlösungen. Teil III. Modelluntersuchungen zum Imprägnierprozeß an CellulosehohlfasernTeil II: Acta Polymerica 33 (1982) 561-566. (1982)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 33 (1982), S. 667-671 
    Details
    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 impregnation of cellulose fibres with phenolic resins are influenced by viscosity (degree of condensation and concentration of solution), surface tension and diameter of capillaries qualitatively (laws of HAGEN POISEUILLE and capillaries). After drying the cellulose fibres involve pores. The film of resins at the walls of fibres is not homogeneous. It is possible that during the impregnation the polymers and the solvent are separated.
    Notes: Der Imprägnierprozeß von Hohlen Cellulosefasern mit Phenolharzlösung wird qualitativ von der Viskosität (vom Kondensationsgrad bzw. vom Molgewicht und von der Konzentration der Lösung), der Oberflächenspannung sowie dem verwendeten Kapillarradius (HAGEN-POISEUILLESCHES Gesetz, Kapillargesetz) beeinfulßt. Nach dem Trocknen verbleibt im Inneren der Cellulosehohlfasern ein Hohlraum. Die Wandbeschichtung mit Harz ist nicht homoge. Während des Imprägnierozesses tritt vermutlich eine Auftrennung in Harz und Lösungsmittel ein.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1982.010331111
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