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  • Polymer and Materials Science  (23,333)
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  • 101
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 15 (1984) 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 102
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    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 349-359 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: The Swelling Behaviour of Thermosetting MaterialsThe moisture absorption of moulded materials can endanger a construction because of the change in volume of various parts. Therefore it is necessary to know the maximum possible swelling of the moulded materials employed at different relative humidities. The swelling of modified phenolic resin systems are described. Wood flour (which absorbs moisture) and powdered minerals (which in this case can be considered as inert) were used as fillers.Different methods have been developed to calculate the maximum possible swelling after a relatively short testing time (ca. 1000 h).
    Notes: Die Feuchteaufnahme eines Formstoffes kann durch die damit verbundene Volumenänderung des Formteils die Funktion einer Baugruppe gefährden. Daher muß die maximal mögliche formstoff- und umgebungsfeuchtespezifische Quelldehnung der eingesetzten Formstoffe bekannt sein. Am Beispiel von Ein-, Zwei- und Dreistoffsystemen mit Phenolharz als Matrixwekstoff wird der Einfluß der Harzträger Holzmehl (im Hinblick auf die Feuchteaufnahme „aktiv“) und Gesteinsmehl („inaktiv“) auf die Quellung untersucht. In diesem Zusammenhang werden Methoden aufgezeigt, die eine Abschätzung der maximal möglichen Quelldehnung nach relativ kurzer Versuchsdauer (etwa 1000 h) ermöglichen.
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  • 103
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    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 24-34 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Evaluation of Recent Models for Short Fatigue CracksIn the present study some new procedures for the evaluation of the propagation behavior of small cracks at notches which were originally proposed by T. H. Topper et al. and by K. J. Miller et al. are considered. They are presented in a manner that they can immediately be used for practical applications. The basis of the procedures and their ranges in application are considered and they are compared to conventional fracture mechanics analyses.In a second part of the study still existing limitations in the physical basis of the procedures are outlined and some aspects regarding the extension of the range in application of the procedures to variable amplitude loading histories are given.
    Notes: In der vorliegenden Arbeit werden neuere im Schrifttum mitgeteilte Methoden (Verfahren nach T. H. Topper u. Mitarbeiter und nach K. J. Miller und Mitarbeiter) zur Beschreibung des Ausbreitungsverhaltens kleiner Risse an Kerben betrachtet und in der Weise aufbereitet, daß sie unmittelbar in der Praxis anwendbar sind. Es erfolgt eine ausführliche Darstellung der Grundlagen und des Anwendungsbereichs der Methoden, ferner ein Vergleich mit konventionellen Lösungsansätzen auf der Grundlage der linear-elastischen Bruchmechanik (LEFM).Anschließend werden die derzeit noch bestehenden Beschränkungen in den physikalischen Grundlagen der betrachteten Methoden angegeben. Es werden Weiterentwicklungsschwerpunkte im Hinblick auf die allgemeine Anwendung der Methoden auf Betriebsfestigkeitsprobleme aufgezeigt.
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  • 104
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    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 124-132 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 105
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    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 15 (1984), S. A30 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 106
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    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 15 (1984) 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 107
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    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 172-176 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Long Term Creep Tests of Polypropylene at 120 °CThe mechanism of damage in the pipe wall during the internal pressure creep test of polypropylene-pipes at a test temperature of 120° is described. The resulting consequences from the investigations relating to the test method are shown and a test station with automatic recording of the time of damage is presented.Further on solutions are explained to eliminate the security risks during the tests of big pipes. A practical performance is described. On the basis of the time-temperature-correlation of the long term behavior of polypropylene the mathematical basis to interpolate minimum requirements for quality control are presented.
    Notes: Die Schädigungsmechanismen in der Rohrwand bei der Zeitstand-Innendruckprüfung von Rohren aus Polypropylen und einer Prüftem-peratur von 120 °C werden beschrieben. Die sich daraus ergebenden Konsequenzen hinsichtlich der Prüftechnik werden aufgezeigt und ein Prüfstand mit selbsttätiger Erfassung des Versagenszeitpunkts für die Serienprüfung vorgestellt. Desweiteren werden Lösungsmöglichkeiten zur Beseitigung des Sicherheitsrisikos bei der Prüfung von Großrohren erläutert und eine praktische Ausführung beschrieben.Auf der Basis der Zeit-Temperatur-Korrelation des Festigkeitsverhaltens von Polypropylen werden die mathematischen Grundlagen zur Interpolation von Mindestanforderungen für die Qualitätskontrolle angegeben.
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  • 108
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. A38 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 109
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Resistance of Various Steel Types and Nickel-Base Alloys Under the Influence of Nitriding Gases in Ammonia Syntheses PlantsThe paper describes test results obtained during 5 years of practical trials with heat-resisting steels, steels for hydrogen service, austenitic steels and nickel-base alloys under the nitriding operation conditions found in an ammonia plant at temperatures of more than about 400°C. During the test, nitriding rates and depths at high temperatures and under stresses were established, as well as changes in the mechanical properties as a result of nitriding.Based on the test results and the knowledge of the subject matter, recommendations and service condition limits for material selection are given.The superior behaviour of austenitic materials, especially with increasing nickel contents, could be confirmed.An attempt is made to find an explanation for the reduced resistance to hydrogen attack under the influence of nitridation.
    Notes: Beschrieben werden Versuchsergebnisse einer 5jährigen praktischen Erprobung an warmfesten, druckwasserstoffbeständigen und austenitischen Stählen sowie Nickelbasiswerkstoffen unter den aufnitrierend wirkenden Betriebsbedingungen einer Ammoniak-Synthese oberhalb etwa 400°C.Ermittelt wurden Nitriergeschwindigkeiten und -tiefen unter Temperatur- und Spannungseinflüssen sowie die Veränderungen der mechanischen Eigenschaften durch Nitrierung.Aufgrund der Versuchsergebnisse und gleichartiger Kenntnisse werden Empfehlungen und Grenzbedingungen zur Werkstoffauswahl gegeben.Das bessere Verhalten austenitischer Werkstoffe, insbesondere mit steigenden Nickelgehalten, konnte bestätigt werden.Es wird versucht, eine Deutung der Verschlechterung der Druckwasserstoffbeständigkeit unter dem Einfluß der Aufnitrierung zu geben.
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  • 110
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 214-221 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Die geschilderten Oberflachenschutzverfahren wurden entwickelt, um im Maschinen- und Apparatebau mit billigeren Grundwerkstoffen weiterzuarbeiten, aber bei hohem Verschleiß und Korrosionsbeanspruchungen noch eine technische und wirtschaftliche Nutzungsdauer zu erreichen. Durch die laufende Verknappung und damit Verteuerung der Rohstoffe werden die einzelnen Verfahren in Zukunft noch eine wesentliche Steigerung erfahren.
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  • 111
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 222-222 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 112
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 230-237 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Pickling of Steel Tanks for Use in Biological Water Purification Plants as a Pretreatment to the Application of an Organic CoatingHigh-level tanks made from structural steel, so called BIOHOCH®-Reaktoren for biological purification of chemical waste water, had to be protected against corrosion by an organic coating. After the usual pretreatment, which means cleaning of the steel surface by sand or furnaceslag blasting, pittinglike corrosion was observed in two cases. Therefore, the required grade of surface preparation was not available. Nevertheless, to get good preconditions for a sufficient service life, both tanks with a volume of about 20 000 m3 were pickled in such a manner, that the final furnace blasting operation furnished the presumed white metal state.The problematic nature of organic coatings, which has recommended the pickling of the steel surface, is discussed. The selection, realization and controlling of this treatment are specified.
    Notes: Stählerne Hochbehälter zur biologischen Reinigung von Chemieabwässern sollten mit einer Beschichtung gegen Korrosion geschützt werden. Bei der dazu notwendigen Vorbehandlung mittels Strahlen zeigte der Stahl in zwei Fällen eine lochförmige Vorkorrosion, die es verhinderte, daß sich auf diesem Wege die gewünschte Oberflächengüte erreichen ließ. Um dennoch gute Voraussetzungen für eine hinreichende Lebensdauer der Beschichtung zu schaffen, wurden die beiden Reaktoren mit jeweils etwa 20 000 m3 Inhalt so gebeizt, daß eine anschließende Strahlbehandlung den geforderten metallisch blanken Zustand erbrachte.Es wird auf die Problematik von Beschichtungen eingegangen, die es im vorliegenden Fall nahelegte, eine Beizung vorzunehmen. Die Auswahl, Ausführung und Überwachung dieser Behandlung werden beschrieben.
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  • 113
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 59-64 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Comparison of the Material Damage Progression by Intercristalline Stress Corrosion Cracking in the Laboratory and during Service ConditionsSimulation of the stress corrosion attack on structural steel in nitrate containing elektrolytes under practical service conditions. Description of the material damage process and definition of the different corrosion rates which can be deduced therefrom. The laboratory results permit the statement of a minimum and a maximum destruction rate by stress corrosion cracks.The results of measurements during service confirm the findings in the laboratory while the comparable damage pictures during laboratory testings and during service attribute to the understanding of not clarified phenomena of the damage process during service.
    Notes: Simulation des Spannungsrißkorrosionsangriffs von Baustählen in nitrathaltigen Elektrolyten unter praxisgerechten Prüfbedingungen. Beschreibung des Verlaufs der Werkstoffschädigung und Definition der unterschiedlichen Zerstörungsgeschwindigkeiten, die sich daraus ableiten lassen. Die Laborergebnisse erlauben die Angabe einer minimalen und maximalen Zerstörungsgeschwindigkeit durch Spannungsrißkorrosion.Die Ergebnisse von Betriebsmessungen bestätigen die im Labor ermittelten Befunde, wobei die vergleichbaren Schadensbilder bei der Laborprüfung und im Betriebseinsatz zum Verständnis von nicht geklärten Phänomenen des Schadensablaufs im Betrieb beitragen.
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  • 114
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    Materialwissenschaft und Werkstofftechnik 15 (1984) 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 115
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 88-94 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Hardfacing-Methods and their Application in the Materials-Technology and TribologyDuring the last few years more and more efforts have been made to reduce or even avoid material losses, caused either by mechanical or corrosive attack, by the means of protecting metal surface protection. In fact, the expenses needed in the Plastic-Technology for the disposition of wear-spares in West Germany amount to half a billion DM a year [1]. If all the damages by wear and corrosion are included, the losses world-wide rise to more than 80 billion DM/year. Thus not only technical but most of all economical reasons promote the rapid development of different hardfacing methods. The various methods are presented with ascending temperature of the working materials (s. Fig. 1).
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  • 116
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 96-102 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Influence of Oxygen Traces on the Properties of Tungsten Heavy MetalsInvestigation carried out with differently sintered W heavy metals showed that careful pre-reduction before liquid phase sintering is essential for obtaining satisfactory mechanical properties; otherwise oxide layers at the phase boundaries deteriorate the interface strength and thus cause premature fracture. Understandably, the water vapour content of the furnace atmosphere is of considerable importance. Appropriate sintering anticipated, even severely oxidized green compacts result in highly ductile heavy metals. Addition of scavengers, e.g. Cr or V, instead of the pre-reduction improves the interface strength, the mechanical properties however remain unsatisfactory.
    Notes: Untersuchungen an nach verschiedenen Zyklen gesinterten Schwermetallen zeigten, daß sorgfältige Reduktion vor dem Flüssigphasensintern notwendig ist, um die beträchtlichen Ausgangsmengen an Sauerstoff zu entfernen; andernfalls werden aufgrund der durch Oxidbelegung verschlechterten Haftfestigkeit zwischen W-Körnern und Binderphase nur sehr schlechte mechanische Eigenschaften erhalten. Der Wassergehalt der Ofenatmosphäre spielt naturgemäß eine bedeutende Rolle; bei richtiger Führung der Sinterung werden auch von stark oxidierten Grünlingen ausgezeichnete Schwermetalle erhalten. Zusatz von Scavengern, wie Cr oder V, anstatt der Vorreduktion verbessert zwar die Haftung der Phasen, die Eigenschaften bleiben aber unbefriedigend.
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  • 117
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. I 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 118
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 132-140 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Investigations of the Local Composition of Glass Fibers with the Help of the Scanning Electron MicroanalysisVarious glass-fiber types show different chemical resistance in the surrounding of aggressive media. Through the influence of inorganic acid or alkali media certain elementary glass fibres can be leached. This effect can be seen optically in some kinds of glass-fibers. Other glass-fiber types show no optical change in the surface, although there is an aggressive attack Now it is possible to understand the leaching process in glass-fibers with the help of the scanning electron microanalysis. In that way corrosion procedures of various glass-fiber types can be better described.
    Notes: Verschiedene Glasfasertypen weisen gegenüber aggressiven Umgebungsmedien eine unterschiedliche Chemikalienresistenz auf. Durch die Einwirkung saurer oder alkalischer Medien können einige Elementarglasfasern ausgelaugt werden, was sich optisch verfolgen lassen kann, andere Glasfasern wiederum zeigen kaum optische Veränderungen. Mit Hilfe der Röntgenmikroanalyse besteht nun die Möglichkeit die durch den Auslaugprozeß hervorgerufene chemische Veränderung der Glasfaserzusammensetzung verschiedener Typen quantitativ bzw. semiquantitativ zu erfassen. Dadurch lassen sich Korrosionsvorgänge an einzelnen Elementarglasfasern besser beschreiben als bisher.
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  • 119
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 177-183 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Application of Metallographic Replica Technique on Material Examination and Failure AnalysesFor evaluation of technical facilities with regard to their safety and availability often informations on the microstructure of the components are required without having the possibility for taking a sample. In such cases a non-destructive metallographic examination by application of the replica technique on site has proved useful and indispensable. Although this technique is adequatly known today its evidence is sometimes still discussed amongst experts. As a contribution to this subject performance and interpretation of this special form of metallographic investigation are described below and the application advantages are pointed out by examples from chemical plants.
    Notes: Für die Beurteilung technischer Anlagen hinsichtlich ihrer Sicherheit und Verwendbarkeit werden oft Aussagen über den Gefügezustand der Bauteile verlangt, ohne daß eine Probenahme zur metallographischen Untersuchung möglich ist. In solchen Fällen hat sich eine zerstörungsfreie mikroskopische Untersuchung vor Ort mittels Gefügeabdrücken als nützlich und unentbehrlich erwiesen. Über die Aussagefähigkeit dieses Prüfverfahrens kommt es in der betrieblichen Praxis nach wie vor zu Diskussionen. In vorliegender Arbeit wird über Durchführung und Auswertung dieser Sonderform metallographischer Untersuchungen berichtet und die Anwendbarkeit an Beispielen aufgezeigt.
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  • 120
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 277-287 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Theoretical Foundations for the Application of Fracture Mechanics to Fibre Reinforced CompositesThis work gives a survey of the theoretical problems arising from the application of fracture mechanical concepts to fibre-reinforced composite materials.A classification of existing models into macro- and micromechanical is proposed, the derivation of essential equations outlined and some graphical illustrations of the resulting formulae are shown.
    Notes: Diese Arbeit gibt einen Überblick über die theoretischen Probleme, die sich bei der Anwendung bruchmechanischer Konzepte auf faserverstärkte Verbundwerkstoffe ergeben.Eine Einteilung der existierenden Modelle in macro- und micro-mechanische wird vorgeschlagen, die Herleitung der wichtigsten Gleichungen skizziert und graphische Illustrationen zu den resultierenden Formeln werden gezeigt.
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  • 121
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 122
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 315-323 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Mit Hilfe experimenteller und numerischer, sowie zeichnerischer Verfahren wurden Wege aufgezeigt, die Eigenspannungen bei Verbundkörpern unter Berücksichtigung des nichtlinearen elastoplastischen Material-Verhaltens zu berechnen bzw. zu konstruieren. Es besteht somit die Möglichkeit, das Verhalten der Verbundkörper vorauszubestimmen, insbesonders die Kennwerte der statischen und der dynamischen Beanspruchungen zu berechnen. Die erzielte gute Überein- stimmung von experimentellen und errechneten Werten der Verbundkörper aus Stahl- und Aluminiummaterial ist auf Verbundkombinationen mit anderen Materialien übertragbar. Weiterführungen der zeichnerischen Schnittgrößenermittlung könnten die Konstruktion des Spannungs-Dehnungs-Diagrammes eines Verbundkörpers zum Ziel haben. Hierbei ist von gleichen Überlegungen wie bei der Bestimmung des inneren Gleichgewichtes auszugehen.
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. A75 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 124
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 46-49 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Gewichtsfunktionen und Spannungsintensitätsvergrößerungsfaktoren für elliptische und halbelliptische Fehler unter beliebiger Normalspannung - Teil IIOberflächenfehler unter Spitzenspannungen werden untersucht. Das Berechnungsverfahren basiert auf der allgemeinen Form der Gewichtsfunktion für einen elliptischen Fehler in einem unendlichen Körper. Zwei Punkte auf der Ellipsenkontur werden untersucht. Ein neues, für alle a/t-Werte gültiges Korrekturverfahren für die Übertragung vom eingebetteten auf den Oberflächenfehler wird vorgestellt. Gewichtsfunktionen für beide Punkte mit dem Halbachsenverhältnis a/c als Parameter werden gefunden. Im Falle des Endpunktes der kleineren Achse sind alle Gewichtsfunktionen durch eine Gleichung beschreibbar (Lambda-Funktion von Heuman). Die Spannungsintensitätsvergrößerungsfaktoren für verschiedene a/c-Werte des Oberflächenfehlers werden bei verschiedenen Spannungsverteilungen angegeben.
    Notes: Surface cracks under peak stresses are investigated. The calculational procedure is based on the general form of the weight function for an elliptical crack embedded in an infinite solid. Two points on the contour of the ellipse are investigated. A new correction procedure for transfer from the embedded crack to surface crack configurations is presented, which is valid for all a/t-values. Weight functions for both points have been found with the crack aspect ratio a/c as parameter. For the point at the end of the minor axis all weight functions for embedded cracks are describable by one equation only (using Heuman's lambda function). For various a/c-ratios of the surface crack under different stress distributions the stress intensity magnification factors are given.
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. A15 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 83-87 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Spannungsintensitätsfaktoren für schlanke OberflächenfehlerEs wird ein Berechnungsverfahren für zug- und biegebelastete Platten mit Oberflächenfehler von Halbachsenverhältnissen a/c ≤ 0,2 und verschiedenen relativen Fehlertiefen a/t vorgestellt. Hierbei wird ein weiterentwickeltes “Line-Spring”-Modell verwendet. Die K1-Werte werden entlang der Fehlerkontur berechnet.Die K1-Werte für den tiefsten Punkt eines Oberflächenfehlers werden durch zwei bekannte Grenzkurven eingehüllt: Die obere Grenzkurve ist identisch mit der Lösung für den Randriß (a/c = 0). Die untere Grenzkurve wird nach den Ergebnissen von Newman und Raju für a/c = 0,2 beschrieben. Die ermittelten K1-Werte korrespondieren gut mit beiden Kurven.Bei großen relativen Fehlertiefen a/t liegen die Maxima von K1 zwischen dem tiefsten Punkt Q′ und dem Oberflächendurchstoßpunkt Q″ des Fehlers. Dieses Ergebnis vermag neben anderen Gründen zu erklären, daß beim Wachstum von Oberflächenfehlern die halb-elliptische Form mitunter nicht erhalten bleibt.
    Notes: A calculation procedure for plates with semi-elliptical surface cracks under tension and bending with aspect ratios of a/c ≤ 0.2 and arbitrary relative crack depths a/t is presented. For the computation an improved line spring model is used. K1-values are calculated along the crack contour.For the deepest point of a surface crack the K1-values are terminated by two well known threshold curves: The upper bound curve is identical with the solution for the edge crack (a/c = 0). The lower bound is described by the results after Newman and Raju for a/c = 0.2. The present K1-values are in good agreement with both curves.For high a/t-ratios the maximum K1-value is found between the deepest and the surface edge point (Q′ and Q″) of the crack. This result could explain among others that crack growth does not conserve the semi-elliptical shape sometimes.
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 107-107 
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. A18 
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    Materialwissenschaft und Werkstofftechnik 15 (1984) 
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 386-393 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Applicability of Different Etching Methods for Metals - Comparing Investigation of Metallographic Etching ProceduresThe feasibility of different etching techniques in laboratory practice is mainly appointed by the reproducibility of the metallographic micro-structure, which is dependent on the etching method, the etching time and a practical handling of the etching procedure. Comparing investigations concerning the applicability of chemical, electrolytic and ionic etching methods for metals and alloys in electrotechnical industry - with the aim to estimate efficiency and reproducibility of the micro-structure resulting from the different techniques - have been done. Micro-structure estimation will be done by different methods of light-microscopy.In any case physical ion-etching turns out to be the less problematic etching method - in comparison with chemical and electrolytic techniques. Ion etching shows a good reproducibility and allows the simultaneous etching of different materials. The summarizing valuation of the different etching methods includes a list of optimum etching parameters for copper, brass copper-tin and copper-beryllium alloys.
    Notes: Die Einsatzmöglichkeiten unterschiedlicher Ätzverfahren in der Laborpraxis werden im wesentlichen bestimmt durch die Reproduziorbarkeit der ausgebildeten Gefügestrukturen - als Funktion einer bestimmten Ätzmethode, der Ätzzeit und der problemlosen Handhabung der Ätzprozedur. Zur Anwendbarkeit des chemischen und elektrolytischen Ätzens, sowie des Ionenätzens bei Metallen und Legierungen der Elektrotechnik wurden vergleichende Untersuchungen mit dem Ziel durchgeführt, eine Beurteilung von Güte und Reproduzierbarkeit der nach den verschiedenen Ätzprozessen entstandenen Gefügebilder zu ermöglichen.Die Abbildung der Gefügestrukturen geschieht mit Hilfe unterschiedlicher lichtmikroskopischer Beobachtungsverfahren.Das physikalische Ionenätzen erweist sich gegenüber chemischen und elektrolytischen Ätzverfahren in allen Fällen als die problemlosere Ätzmethode, die neben einer guten Reproduzierbarkeit zudem ein gleichzeitiges Ätzen unterschiedlicher Materialien in einem Werkstoff ermöglicht.Eine zusammenfassende Wertung der verschiedenen Ätzverfahren umfaßt die Angabe optimaler Ätzparameter für die Werkstoffe Kupfer, Messing, CuSn 8 und Kupfer-Beryllium.
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. A59 
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 268-276 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Residual Stresses in Continual, Unidirectional Reinforced Fibre-Composites and Composite-ConstructionsInternal stresses in composite are determining the static or dynamic properties of these elements. These inbuilt stresses are extending or shortening the failure of the individual materials. If the internal stresses in a composite are known the mechanical characters of the composite can be calculated.With aid of experimental, numerical or graphical methods it is shown to calculate or construct the internal stresses of unidirectional, continual reinforced fibrecomposites. The nonlinear material-characteristics of the individual composite-materials are taken account of.The good agreement between experiment and calculation of the residual stresses can be demonstrated with examined stealwire-aluminium-composites. The method how to calculate the residual stresses may be transfered to other combinations of composite by the same way.
    Notes: Eigenspannungen in Verbundkörpern bestimmen deren statisches und dynamisches Festigkeitsverhalten. Innere Spannungen verkürzen oder verlängern die Beanspruchbarkeiten der Einzelkomponenten. Bei Kenntnis der inneren Spannungen lassen sich die Festigkeitskennwerte exakt errechnen.Mit Hilfe experimenteller und numerischer sowie zeichnerischer Verfahren werden Wege aufgezeigt, die Eigenspannungen von unidirektional mit kontinuierlichen Fasern verstärkten Verbundkörpern zu berechnen bzw. zu konstruieren. Hierbei wird das nichtlineare elastoplastische Materialverhalten der Verbundkomponenten berücksichtigt.Die erzielte gute Übereinstimmung von experimentellen und errechneten Werten der exemplarisch untersuchten Verbundkörper aus Stahldrähten und Aluminiummaterial, ist auf Verbundkombinationen anderer Materialien bei gleicher Vorgehensweise übertragbar.
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. A62 
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. A68 
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. A78 
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 363-366 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 367-371 
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    Description / Table of Contents: The Design of Ceramic ComponentsIt is expected that engineering ceramics will be used for components outside the traditional fields of applications for ceramics. Some of the basic methods of production engineering practiced with metals are compared to the production of ceramics.Here the reasons for certain restrictions in designing with ceramics can be detected.Information is given about some basic properties, tolerances and literature discussing the design with ceramics.
    Notes: Allgemein wird erwartet, daß Bauteile aus Ingenieurkeramik Anwendung finden außerhalb der traditionellen Anwendungsgebiete von Keramik. Methoden der Fertigungstechnik von Metall werden verglichen mit denen von Keramik, so daß die Gründe der Beschränkungen beim konstruktiven Entwurf keramischer Bauteile aufgezeigt werden können.Für den Entwurf von Bauteilen aus Ingenieurkeramik wird Information über grundlegende Eigenschaften, Toleranzen und Literatur mit Konstruktionsbeispielen zusammengestellt.
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 399-401 
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Grip °and Specimen Heating-System for Fatigue Tests at the Temperature-Range 20 °C 〈 T 〈 600 °CA grip and specimen heating system for fatigue tests is presented. The equipment is easily to handle, long-time stable and available up to a test-temperature of 600 °C also with inert environment. Specimens can be fixed without bending moments.
    Notes: Es wird eine einfach zu handhabende, momentenfrei spannende, langzeitstabile und bis etwa 600 °C Versuchstemperatur einsetzbare Probeneinspann- und Heizvorrichtung vorgestellt, die sich bei Dauerschwingversuchen auch unter inerten Umgebungsbedingungen vorzüglich bewährt hat.
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. A86 
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 186-189 
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    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Contribution to the Influence of Pressurized Hydrogen on the Mechanical Properties of SteelsThe investigation method of using hollow specimens in tensile tests to examinate steels for hydrogen service is described. Reduction of area after fracture, Z, resulting from these tensile tests with constant strain rates shows not only a significant but also a constant difference between hydrogen and nitrogen when being plotted versus strain rate. Therefore a newly introduced term named “Index of embrittlement” and characterized by the relation of Z with nitrogen and with hydrogen was found to be independent of strain rate. With strain rate ε = 10-6 s-1 chosen for a “critical” one because of lacking in a maximum index of embrittlement several European steels for hydrogen service were tested to find out their individual index of embrittlement. Assisted by light optical microscopy it was found that there is a special correlation between microstructure, index of embrittlement and tensile strength of a given steel grade.
    Notes: Eine Methode zur Durchführung von Zugversuchen an Hohlproben aus Stählen für den Einsatz mit Wasserstoff wird beschrieben. Die Ergebnisse der unter konstanten Dehngeschwindigkeiten durchge-führten Zugversuche zeigten besonders für die Brucheinschnürung Z deutliche und in Abhängigkeit von der Dehngeschwindigkeit konstante Unterschiede zwischen Stickstoff und Wasserstoff als Füllgas der Hohlproben. Ein aus den Wertepaaren der Brucheinschnürung unter Stickstoff bzw. Wasserstoff gebildeter sogen. “Versprödungs-index” I ist daher unabhängig von der Dehngeschwindigkeit eine Konstante für jeden einzelnen Stahl. Dieser Versprödungsindex wurde für verschiedene Vergütungsstähle deutscher und französischer Herkunft bestimmt. Es zeigte sich eine charakteristische Abhängigkeit zwischen Versprödungsindex, Mikrogefüge gemäß Wärmebehandlung und Zugfestigkeit, wodurch eine rangmäßige Zuordnung der Stähle hinsichtlich ihrer Versprödungsneigung möglich ist.
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 206-209 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Prestressing of Brick Lined Vessels with Regard to the Thermal Creeping of Mortars Based on Condensating ResinsCeramic linings, applied in steel vessels to protect these from chemical attacks, have a lower thermal expansion coefficient than the steel shell. Moreover ceramic is very sensitive to tensile stress. If temperature in the subsequent operation exceeds very much those during application of the brick lining, the greater expansion of the steel shell put the lining under tensile stress and may cause cracks which nullify its protection effect. Remedy by thicken the brick lining or by external heating of the shell during the application of the masonry is limited only.More effective is a pre-stressing of the brick lining before or whilst the start up. This procedure bases on the property of irreversible thermal creeping, owned by the phenolic and furan resin based mortars, which are used for bedding and pointing of the brick linings. This property of the above mortars formerly has been taken for mere swelling. It was not yet exactly determinable and so making use of it was rather unsave.This treatise contains data about the possible dimensions of the thermal creeping, depending on kind and age of the mortar as well as on the thermal increase and the reached amount of temperature. Reference is given to the practical use of this knowledge for the execution of prestress cooking.
    Notes: Keramische Ausmauerungen in stählernen Behältern, die diese gegen Angriffe durch Chemikalien schützen sollen, haben eine geringere Wärmedehnzahl als der Mantel. Zudem ist Keramik gegen Zugspannungen sehr empfindlich. Bei betrieblicher Erwärmung gegenüber der Ausmauerungstemperatur kann das Mauerwerk infolge der größeren Ausdehnung des Stahlmantels unter so starke Zugbeanspruchung geraten, daß Risse entstehen, die die Schutzwirkung der Ausmauerung zunichte machen. Abhilfe durch dickeres Mauerwerk oder äußeres Erwärmen des Mantels während des Ausmauerns ist nur begrenzt möglich.Wirkungsvoller ist es, der Ausmauerung vor oder bei der Inbetriebnahme eine Druckvorspannung zu geben. Diese Maßnahme beruht auf der Eigenschaft des irreversiblen thermischen Fließens der zum Verlegen und Verfügen der keramischen Ausmauerung dienenden Kondensationsharzkitte. Dieses, bisher als “Quellung” angesehene Kitt-Verhalten war nicht genauer bestimmbar und seine Anwendung deshalb mit Unsicherheiten behaftet.Die Abhandlung enthält Meßdaten über das mögliche Ausmaß des Fließens in Abhängigkeit von Art und Alter des Kittes sowie von der Steigerungsrate und der erreichten Höhe der Temperatur. Hinweise für die praktische Anwendung dieser Erkenntnisse bei Vorspannkochungen werden gegeben.
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 222-222 
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. A49 
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    Description / Table of Contents: Welding Engineering in Chemical Systems Construction - Examples for Selection and Welding Processing of Materials as to Their Operational VerificationWelding manufacturing occupies undoubtedly a key position in the construction of chemical apparatus and systems. It is possible to application-specifically select out of a variety of structural materials and welding fillers. Corrosion resistance, thermal and mechanical characteristics, especially any differences in the time-history of loading are the crucial criteria. In addition, the effects of welding on the material properties must be considered.Below examples will be given as to material criteria concerning specifications and selection, but primarily with respect to the corrodibility of stainless CrNi(Mo) steels and the appropriate welding fillers.
    Notes: Die schweißtechnische Fertigung nimmt beim Bau von Apparaten und Anlagen der chemischen Industrie ohne Zweifel eine Schlüsselposition ein.Aus einer Vielzahl von Konstruktionswerkstoffen und Schweißzusatzwerkstoffen kann, auf den Anwendungsfall bezogen, eine Auswahl getroffen werden. Das Korrosionsverhalten, die thermischen und mechanischen Eigenschaften, insbesondere auch die möglichen Unterschiede im zeitlichen Verlauf der Beanspruchung, sind die Hauptkriterien. Hierzu kommen noch die Einflüsse der schweißtechnischen Fertigung auf die Werkstoffeigenschaften.Werkstoffkriterien im Hinblick auf Anforderungen und Auswahl, besonders das Korrosionsverhalten der nichtrostenden Cr-Ni-(Mo)-Stähle und der entsprechenden Schweißzusatzwerkstoffe, werden beispielhaft aufgezeigt und Problemlösungen vorgestellt.
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 1-9 
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    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: The Damage Line of the WöhlerdiagramSometimes, Wöhlerdiagrams are supplemented by so-called damage lines or French-lines, synonymously. Due to the statistical nature of fatigue events, however, Wöhlerdiagrams more and more are statistically ascertained and described by curves which commonly are referred as to probability-stress-cycle curves (P-S-N). Accordingly, it was to find out, whether the feature “damage” might be described in a similar way, aiming at Pd-S-N curves (Pd = Probability of damage) within the expected damage field.Using the steels Ck 35 and 34 CrMo 4 quenched and tempered, the statistically planned and evaluated investigations showed that within the Wöhlerdiagrams of these steels large damage fields can be defined which extend from far before the ranges of finite life till far into these ranges (of scatter). Pd-S-N curves are given. Satisfactory shortcut-methods for estimating such curves using features as specimens' temperature and deformation during cyclic pre-loading could not be developed.By progressively increasing and - another sample - decreasing load tests to the same account of 0,34 Palmgren-Miner-damage specimens showed remarkable differences when compared within French's concept of damage.
    Notes: Wöhlerdiagramme werden bisweilen durch Schadenslinien ergänzt. Eine gängige Ermittlungsmethode ist mit dem Namen von French verbunden. In den vergangenen Jahrzehnten setzte sich angesichts der teilweise enormen Streuung der Lebensdauer identisch beanspruchter Prüflinge desselben Kollektivs eine zunehmend statistische Auffassung des Wöhlerdiagrammes durch. Diese Auffassung auch bezüglich des Merkmals Schädigung zu entwickeln und einer experimentell abgesicherten Überprüfung zu unterziehen, war naheliegend.Großzahluntersuchungen an Ck 35 und 34 CrMo 4 erwiesen die Existenz von Schadensbereichen, die weit vor dem Lebensdauerstreugebiet beginnen und sich bis weit in dieses hinein erstrecken. Analog zur Lebensdauer läßt sich die Schädigung statistisch beschreiben, jedoch ist das dazu erforderliche Versuchsaufkommen beachtlich. Umfangreiche Bemühungen, über Temperatur-, Verformungs- und Oberflächenuntersuchungen eine weniger aufwendige Kurzzeitmethode der Schädigungsabschätzung zu entwickeln, verliefen unbefriedigend.Zwei Versuchsblöcke, der eine laststeigernd und der andere lasterniedrigend auf gleiche Palmgren-Miner-Schädigung gebracht, zeigten bei einer Überprüfung ihrer Schädigung nach French erhebliche Unterschiede.
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 10-17 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Gewichtsfunktionen und Spannungsintensitätsvergrößerungsfaktoren für elliptische und halbelliptische Fehler unter beliebiger Normalspannung - Teil IOberflächenfehler unter Spitzenspannungen werden untersucht. Das Berechnungsverfahren basiert auf der allgemeinen Form der Gewichtsfunktion für einen elliptischen Fehler in einem unendlichen Körper. Zwei Punkte auf der Ellipsenkontur werden untersucht. Für die Übertragung der Ergebnisse vom eingebetteten auf den Oberflächenfehler wird das Superpositionsprinzip angewendet. Gewichtsfunktionen für beide Punkte mit dem Halbachsenverhältnis a/c als Parameter werden gefunden. Im Falle des Endpunktes der kleineren Achse sind alle Gewichtsfunktionen durch eine Gleichung beschreibbar (Lambda-Funktion von Heuman). Die Spannungsintensitätsvergrößerungsfaktoren für verschiedene a/c-Werte des Oberflächenfehlers werden bei verschiedenen Spannungsverteilungen angegeben.
    Notes: Surface cracks under peak stresses are investigated. The calculational procedure is based on the general form of the weight function for an elliptical crack embedded in an infinite solid. Two points on the contour of the ellipse are investigated. The superposition method is used for transfer from the embedded crack to surface crack configurations. Weight functions for both points have been found with the crack aspect ratio a/c as parameter. For the point at the end of the minor axis all weight functions are describable by one equation only (Heuman's lambda function). For various a/c ratios of the surface crack under different stress distributions the stress intensity magnification factors are given.
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  • 150
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. A7 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 151
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 331-338 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Glassy Carbon Sigradur® - a Material for Chemistry and TechnologyGlassy carbon is a carbon modification characterized by its glasslike fracture behaviour. Raw material, manufacturing, microstructure, and studies on fracture mechanics are discussed and examples for the widespread application of glassy carbon are given.
    Notes: Glaskohlenstoff ist eine Kohlenstofform mit glasartigem Bruchbild. Rohstoffe, Herstellungsverfahren und Struktur des glasartigen Kohlenstoffs werden beschrieben, die Ergebnisse bruchmechanischer Untersuchungen diskutiert und ein Überblick über die zahlreichen Anwendungen und Einsatzmöglichkeiten gegeben.
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  • 152
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 378-386 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Low-Cycle Fatigue of Ductile Steels under Multiaxial DeformationsTo investigate the fatigue behaviour of cyclically softening and hardening steels under multiaxial elastic-plastic strains, axial strain and shear strain controlled fatigue tests under constant amplitude loading were carried out. S-N curves under axial strain and torsional pure shear as well as under combined axial strain and shear, in and out of phase, were obtained for the cyclically softening tempered steel 30 CrNiMo 8 (similar to AlSI-Type 4340) and the cyclically hardening quenched stainless steel X 10 CrNiTi 189 (AISI-Type 321) in the region of low-cycle fatigue.For both steels, used in the design of vessels, pipings, shafts, etc. the fatigue life to crack initiation is reduced by an out of phase (δ = 90°) shearing of the strained specimens in comparison to the in phase loading. The decrease of fatigue life under out of phase strains is caused by changing direction of principal strains resulting in an interaction of the deformations in all directions of the surface. This interaction is taken into account by a calculation procedure deriving an equivalent strain and predicting the fatigue life under combined strain on the base of S-N curves for unaxial strain.
    Notes: Um das Kurzzeitschwingfestigkeitsverhalten von zyklisch entfestigenden und verfestigenden Stählen unter mehrachsigen elasto-plastischen Beanspruchungen zu untersuchen, wurden dehnungs- und scherungsgesteuerte Schwingfestigkeitsversuche unter Einstufenbeanspruchung durchgeführt. Für den zyklisch entfestigenden Vergütungsstahl 30 CrNiMo 8 und zyklisch verfestigenden austenitischen Stahl X 10 CrNiTi 189 wurden Anrißwöhlerlinien unter reiner Dehnung, reiner Scherung sowie unter kombinierter phasengleicher und phasenverschobener Beanspruchung ermittelt.Bei beiden Stählen, die im Behälter und Rohrleitungsbau häufig verwendet werden, tritt durch die phasenverschobene Beanspruchung (δ = 90°) gegenüber der phasengleichen eine deutliche Minderung der Anrißlebensdauer auf. Diese Minderung erfolgt durch eine Veränderung der Hauptdehnungsrichtungen und durch eine gegenseitige Beeinflussung von Verformungen in verschiedenen Richtungen der Oberfläche. Dieses Verhalten wird durch ein Berechnungsverfahren erfaßt, mit dem eine Vergleichsdehnung abgeleitet wird. Auf der Basis von unter einachsiger Belastung ermittelten Dehnungswöhlerlinien wird anschließend die Anrißlebensdauer für kombinierte Beanspruchung abgeschätzt.
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  • 153
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Thermomechanical Properties of Castable Refractories with Embedded Scaleresistant Steel FibersIn the last years steel fibers were embedded in castable refractories for certain application to increase the thermomechanical properties of refractory concrete.When cheap carbon steel fibers were used, the less oxidation resistance in the high temperature range was a serious disadvantage. Stainless steel fibers were oxidation resistant only up to about 1000 °C when practical used at long time.Now, stainless steel fibers with high chromium (24-26%) and high nickel content (34-36%) were put on the market for embedding in castable refractories. The thermomechanical properties of these composites will be compared with those of earlier investigations. Their will be used steel fibers not only fabricated by cutting of drawn wires but also by melt extraction processing. The interfacial area steel fiber/refractory matrix will be examined and the reaction or oxidation products analyzed by microprobe.
    Notes: Für bestimmte Anwendungen werden in jüngster Zeit Stahlfasern in Feuerbetone eingelagert, um das thermomechanische Verhalten der Feuerbetone zu verbessern.Beim Einsatz preisgünstiger. Kohlenstoffstahlfasern war deren ungenügende Oxidationsbeständigkeit bei hohen Temperaturen von Nachteil. Edelstahlfasern (Cr Ni 18/10) genügten auf Dauer auch nur Temperaturen um 1000 °C.Neuerdings sind hochchromhaltige (24-26%) und hochnickelhaltige (34-36%) Stahlfasern auf dem Markt, die in Feuerbetone eingelagert werden. Die thermomechanischen Eigenschaften dieser Verbundwerkstoffe werden mit denen früherer Untersuchungen verglichen. Dabei werden auch Stahlfasern eingesetzt, die nicht durch Ablängen von gezogenem Draht hergestellt werden, sondern nach dem Melt-extraction-Verfahren aus der Schmelze ausgeschleudert werden. Dabei werden in Abhängigkeit von der Temperatur auch der Grenzbereich Stahlfaser/Feuerbetonmatrix mit Hilfe der Elektronenstrahlmikrosonde untersucht und auftretende Reaktions- bzw. Oxidations-produkte analysiert.
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  • 154
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    Materialwissenschaft und Werkstofftechnik 15 (1984) 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 155
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 420-426 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Investigations to Determine the Size of Corrosion CracksFor determining the size of corrosion cracks with ultrasound a multifrequency test method is described. By applying this procedure corrosion cracks of a size smaller than 2 mm are correctly evaluated independent of their position and of the reflection factor. Examples are presented and discussed for some practical applications.
    Notes: Zur Bestimmung der Größe von Korrosionsrissen bei der manuellen Ultraschallprüfung wird ein Mehrfrequenzenverfahren erfolgreich eingesetzt. Dieses liefert - unabhängig von der absoluten Echoamplitude (Reflexionsfaktor) des Risses und ohne Einschränkungen hinsichtlich der axialen Auflösung - selbst bei geneigten Fehlern Genauigkeiten in der Tiefenbestimmung, die bisher speziell bei kleinen Rißtiefen unter 2 mm nicht realisierbar waren. Beispiele werden vorgestellt und praktische Anwendungen diskutiert.
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 157-172 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Methods to Determine the Behavior of Polyolefines in Contact with Chemical AgentsTwo test methods to determine the behavior of thermoplastics in contact with chemicals were compared. These are the immersion test and the internal pressure creep test of pipes filled with a chemical agent. Concerning the immersion test the mechanical properties of tensile bars after the test procedure were determined. The results only are valid for constructions without any load.In the internal pressure creep tests the influence of a chemical agent and the stress is considered simultaneously. By comparison with the long term behavior under the influence of water the chemical resistance factor is given.The test procedure and the evaluation of the results of the immersion tests were strown at two examples. A test station for internal pressure creep tests with pipes which are filled with a chemical agent is described. Many resistance factors were listed up and their application in two examples explained.
    Notes: Zwei Prüfmethoden zur Ermittlung des Verhaltens von thermoplastischen Kunststoffen bei der Einwirkung von Chemikalien werden gegenübergestellt. Dies sind der Immersionsversuch und der Zeit-stand-Innendruckversuch an Rohrproben mit Mediumfüllung. Beim Immersionsversuch wird die Veränderung der mechanischen Eigenschaften von Zugproben nach der Lagerung im Medium gemessen. Die Ergebnisse sind nur auf mechanisch nicht belastete Bauteile anzu-wenden.Dagegen wird beim Zeitstand-Innendruckversuch mit mediumgefüllten Rohren der kombinierte Einfluß von Medium und Spannungen gleichzeitig erfaßt. Durch Vergleich mit der Zeitstandfestigkeit bei Wassereinwirkung erhält man den Resistenzfaktor, der den Einfluß des Mediums quantifiziert.Die Durchführung und Auswertung von Immersionsversuchen werden an Beispielen gezeigt. Eine Prüfeinrichtung für die Durchführung von Zeitstand-Innendruckversuchen an Rohrproben mit Mediumfüllung wird beschrieben sowie eine große Anzahl von Resistenz-faktoren mitgeteilt und deren Anwendung an zwei Rechenbeispielen erläutert.
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    Materialwissenschaft und Werkstofftechnik 15 (1984), S. 190-190 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 158
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    Polymer Engineering and Science 24 (1984), S. 169-174 
    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: Water-ground Phlogopite micas were classified into narrow particle-size distributions containing flakes with well-defined diameters and thicknesses in order to evaluate the influence of particle size and flake aspect ratio on the mechanical properties of mica-filled polypropylenes, For the purposes of comparison, most of the injection-molded specimens contained 40 percent (by weight) mica. As expected, the flexural and tensile modulus values increased in proportion to the aspect ratio over the range from 30 to 60 to a maximum of 8 GPa. The measured tensile strengths of the mica-filled polypropylenes increased substantially as the flake diameter became smaller, but did not correlate with the flake aspect ratio. The attainable properties were frequently dependent upon the method of mixing, and considerable care was necessary to ensure proper dispersion and adequate coupling. Intensive mixing, as in a Gelimat Mixer, may cause in situ delamination and particle-size reduction of the mica filler particles, leading to a marked increase in tensile strength of the resulting composite. The mica-filled compounds could be reprocessed many times without significant loss of properties, particularly compounds having mica particles less than 40 μm in diameter. The fracture energies (notched Izod) and the heat-distortion temperatures were not appreciably influenced by the size or aspect ratios of the mica within this range. Increased fracture toughness could be achieved by reducing the mica concentration or employing a polypropylene copolymer. Guidelines are presented to indicate the preferred characteristics of mica fillers and the influence of mixing conditions on performance.
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    Polymer Engineering and Science 24 (1984), S. 30-41 
    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: A mathematical model has been developed to compute the molecular weight distribution (MWD) in the polyethylene terephthalate (PET) manufacturing process. Unlike the previous efforts, this model takes into account the influence of side reactions and various interchange reactions on MWD. The process of blending of molten polyester chips has also been simulated with a view to calculate the equilibrium MWD as well as the time required to reach the equilibrium MWD. The1 significance of the results has been discussed in terms of industrial operations involving PET polymerization and PET blending.
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    Polymer Engineering and Science 24 (1984), S. 541-543 
    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
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    Polymer Engineering and Science 24 (1984), S. 555-562 
    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: Methods of preparation and of determining miscibility limits for partially miscible binary polymer blends are described. An equation-of-state, theoretical description of this behavior is introduced and the terms describing interactions within the system discussed, Values of these interaction terms are obtained by fitting the models to measured cloud point curves, heats of mixing data, etc. The use of neutron scattering experiments to obtain molecular conformation and interaction parameters is described and a comparison made with values extracted from the thermodynamic measurements.
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    Polymer Engineering and Science 24 (1984), S. 163-168 
    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: Dextran-g-poly(acrylamide-co-sodium acrylates) were prepared by partial hydrolysis of dextran-g-poly(acrylamides) with controlled numbers and lengths of grafted chains. This hydrolysis route proved to be more effective than Ce(IV)-induced cografting of acrylamide and sodium acrylate comonomers onto dextran in producing the desired graft-copolymer structures. The resulting copolymers were characterized and the effects of composition, temperature, ionic strength, and shear rate on dilute solution rheological properties were studied.
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    Polymer Engineering and Science 24 (1984), S. 194-204 
    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: The formation of polyethylene terephthalate (PET) has been modeled to have reactions with monofunctional compounds, redistribution, and cyclization reactions in addition to the usual polycondensation step. In the final stages, the overall polymerization is mass-transfer controlled and solution of the reactor performance equations have been determined through the orthogonal collocation technique. This technique is found to be considerably more efficient for PET reactors compared to the finite difference method; the use of ten collocation points gives results which are close to the exact solution.
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    Polymer Engineering and Science 24 (1984), S. 218-225 
    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 review focuses on a new type of para-catenated aromatic polymer being used in the preparation of high-performance films and fibers of exceptional strength, thermal stability, and environmental resistance, including inertness to essentially all common solvents. Polymers of this type include cis and transpoly(p-phenylene benzobisoxazole) (PBO), and the cis and trans forms of the corresponding poly(p-phenylene benzobis-thiazole)(PBT). The purpose of this paper is to summarize the authors' theoretical work on the structures, conformational energies, intermolecular interactions, and electronic properties of PBO and PBT chains, including the protonated forms known to exist in strong acids. The emphasis is on how such studies provide a molecular understanding of the unusual properties and processing characteristics of this new class of materials.
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  • 165
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    Keywords: Chemistry ; Chemical Engineering
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    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Poly(p-phenylene terephthalamide) (PPD-T) films have been prepared by continuous extrusion of liquid crystalline 17 percent PPD-T/sulphuric acid solutions through an annular die followed by coagulation, Films extruded without drawdown exhibit some polymer chain orientation in the machine direction. This is increased by uniaxially drawing down films. Films produced with a lubricated conical mandrel sitting between the die and the coagulation bath exhibit an equal biaxial orientation. The uniaxially oriented films exhibit highly anisotropic mechanical properties, while the mandrel-produced film exhibits balanced properties. Heat treatment at 350°C results in significant enhancement of the tensile strength of the mandrel film. Void structures in the films have been investigated by mass density, scanning electron microscopy (SEM), and small-angle X-ray scattering (SAXS). Density measurement indicate a void content decreasing with decreasing film thickness and heat treatment. SEM locates micron-size voids in the thickest films, apparently caused by rapid coagulation. SAXS indicates much smaller void sixes which are roughly prolate ellipsoids (long axis in machine direction) for uniaxial films and oblate ellipsoids (short axis in thickness direction) for the mandrel produced films. Various techniques are used to estimate mean void size.
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    Polymer Engineering and Science 24 (1984), S. 278-286 
    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: Poly(vinyl chloride) (PVC) and its blends with polybutadiene-acrylonitrile (NBR) (containing 21.7 weight-percent acrylonitrile (AN), a heterogeneous two-phase system; and containing 41.6 weight-percent of AN, a homogeneous one-phase system) and with polyethylene-vinyl acetate (EVA) (containing 45 weight-percent of vinyl acetate (VA), a heterogenous two-phase system; and containing 65 weight-percent VA, a homogeneous one-phase system) were UV-irradiated (at 3500 Å UV-light (solar spectrum)). After UV irradiation the kinetics measurements were made of the formation of hydroperoxy (OOH) and carbonyl (CO) groups and the changes of mechanical properties: tensile strength, elongation to break, and impact energy. As a result of the photooxidative degradation of PVC blends, decreases of mechanical properties were observed. The effects are more severe in PVC/NBR blends, which contain unsaturated bonds (polybutadiene segments) than in the case of PVC/EVA. The phase structure plays an evident role on the UV degradation only of PVC/NBR blends. The photostability of PVC blends can be slightly improved by introducing Tinuvin P or Ni-chelates photostabilizers.
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    Polymer Engineering and Science 24 (1984), S. 292-292 
    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
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    Polymer Engineering and Science 24 (1984), S. 319-327 
    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: An investigation was carried out in order to study the effect of prestrain on the subsequent crystallization of a specific copolyester based on lactic and glycolic acid. This polymer, which can be easily quenched into an amorphous glass, has a Tg of 43°C and when in crystalline form has a melting point of 210°C. Using amorphous films, samples were prestrained to various levels at temperatures not far above Tg. In some cases films were immediately quenched at the prestrain level so as to retain the elongation while others were allowed to immediately retract whereby they showed a relatively small degree of permanent Set. Utilizing birefringence, quenched samples whose initial elongation was maintained showed linear behavior with prestrain while those that retracted showed essentially zero birefringence until a prestrain of about 150 percent after which a small degree of positive birefringence resulted. Wide angle x-ray diffraction (WAXS) showed no signs of crystallinity in all cases. These same films were then quickly taken to 150°C and rapidly crystallized. Again, one series of the prestrained samples were in the elongated state during crystallization whereas the second series was unrestrained during crystallization. Using microscopy and small angle light scattering (SALS), the morphological textures of these crystallized films were investigated. In all cases, spherulitic textures were observed of equivalent size up to a value of about 200 percent elongation the spherulite size systematically decreased with the prestrain an increase in clearly showing that prestrain had a pronounced effect upon the nucleation density. Increasing draw rate displayed a similar effect on nucleation density. Since spherulite size was noted to be the same in either series, it indicated that nucleation was induced as a result of the prestrain and remained irrelevant of whether the sample was allowed to relax or not. The morphology above the transitional state was similar to row structure common to polymers crystallized in the oriented state. WAXS and birefringence was applied to the crystallized materials and it was found that up until the transitional zone, no crystal orientation was observed in either series indicating that although nucleation density was strongly affected up until that point, no orientation was retained within the sample upon crystallization. A simplified model is used to explain the observed results.
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    Polymer Engineering and Science 24 (1984), S. 965-973 
    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: A method based on network theory is developed for characterizing molecular orientation in amorphous polymers. The proposed procedure gives not only the orientation distribution function for the chain segments in the polymer network (and hence the average orientation) but also a quantitative measure of how this orientation is distributed among the various types of entanglement junctions. The orientation of chain segments can be characterized by two parameters, one which gives the average orientation and another which reflects how much orientation is concentrated in long time entanglement junctions. The new method of characterizing orientation is used to interpret tensile strength data for both brittle and ductile failures.
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    Polymer Engineering and Science 24 (1984) 
    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
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  • 171
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    Polymer Engineering and Science 24 (1984), S. 1025-1025 
    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
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  • 172
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    Polymer Engineering and Science 24 (1984), S. 1035-1042 
    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: A study of the crystalline orientation, light transmission, and surface roughness of polyethylene tubular film prepared in our laboratories is presented. The present studies were primarily carried out on low-density (LDPE) and linear-low-density (LLDPE) polyethylene films. The optical properties of a few films of high-density polyethylene (HDPE) prepared for a previous study of morphology were characterized for comparison to the LDPE and LLDPE films. Wide angle X-ray diffraction and birefringence were used to characterize orientation. Both the LDPE and LLDPE films exhibited crystalline texture in which the b-axes tended to be perpendicular to the film surface and the a-axes had some tendency to align with the machine direction. The c-axes tended to be concentrated in the plane of the film with nearly equal biaxial orientation with respect to the machine and transverse directions. Little variation in the crystalline orientation was found with changes of process conditions in the range studied. Birefringence results indicate that the amorphous regions developed an orientation in which the chains tend to be normal to the film surface. The majority of light scattering from these films and a series of HDPE films was from the surface and not from the film interior. The transmission coefficient for the surface contribution was found to be a monotonic decreasing function of the standard deviation of the surface height obtained from surface profiles measured by profilometer. The surface asperites were largest for the HDPE and smallest for the LDPE samples. The intensity of both the surface and interior contributions to the scattering increased with increasing frostline height, i.e., a slower cooling rate. As draw-down ratio and blow-up ratio increase the scattering contribution from the film interior decreases but the contribution from the surface increases somewhat. These effects are discussed in terms of the changes in crystalline morphology and surface roughness produced by flow defects generated during extrusion.
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  • 173
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    Polymer Engineering and Science 24 (1984), S. 1064-1070 
    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: Stress-corrosion data for poly(ethylene terephthalate) reinforced with short glass fibers are provided under various environments and the microscopic observations are compared with the lifetime data. It is concluded that the lifetime behavior coincides with the microstructural features; this aspect is quantified by the statistical analysis.
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  • 174
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    Polymer Engineering and Science 24 (1984), S. 442-454 
    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: The two major problems encountered in industrial liquid-phase addition polymerization are: the heat released by highly exothermic reactions and the great increase in viscosity with conversion. The high rate or heat generation, coupled with the low thermal diffusivity of the reacting system, often lead to thermal runaway. Even with the process kept under marginal control, large temperature variations broaden the product molecular-weight distribution. Temperature control is particularly difficult in the Trommsdorff region, where reaction rate rapidly increases as temperature rises and viscosity builds up. A two-stage process is developed in this work to attack these problems and to achieve continuous operation of poly(methyl methacrylate) bulk polymerization. This process utilizes a continuous stirred-tank reactor (CSTR) as a first-stage prepolymerizer and a spray tower as the second-stage finishing reactor. Use of a CSTR offers good temperature control and product uniformity during the early stages of reaction and eases delivery of the reacting system to the second stage at the desired conversion and molecular-weight level. Spraying the partially polymerized mixture into the tower as fine droplets prior to the onset of gel effect eliminates the problems of transporting, agitating, and mixing a reacting system with a rapidly increasing viscosity. Heat of reaction is efficiently removed by a countercurrent stream of nitrogen in the tower, in direct contact with the falling droplets. The high surface-to-volume ratio of these small droplets facilitates heat transfer, and the problem of heat buildup can be efficiently controlled. Products from the bottom of the tower can then be melt-processed by conventional methods, such as extrusion. Experiments performed in the laboratory have demonstrated the feasibility of this proposed concept. Process optimization was in no way achieved due to serious space and equipment limitations. The process was thus further examined by computer simulation and model parameter sensitivity study. A practical design was recommended based on the model predictions.
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  • 175
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    Polymer Engineering and Science 24 (1984), S. 473-481 
    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: An experimental study was conducted on the injection molding of a thermosetting polyester resin. For the study, a general-purpose unsaturated polyester resin was used, with benzoyl peroxide as initiator. A differential scanning calorimeter (DSC) was used for studying the curing kinetics, under isothermal curing conditions. A plunger-type injection-molding apparatus was constructed, and a rectangular mold cavity with glass windows on both sides was constructed, which permitted us to record on a film the changes in stress birefringence patterns in the mold cavity during the molding operation (i.e., during the isothermal cure, post cure, and subsequent cooling), using a crossed circular polariscope. The injection-molded specimens were used to determine the distribution of the degree of cure at various positions in the flow direction, and to relate the degree of cure to the dynamic mechanical properties.
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  • 176
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    Polymer Engineering and Science 24 (1984), S. 1240-1244 
    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: Standard test specimens of mortar were cured under water for 15 days to achieve satisfactory strength. They were dried without allowing dehydration reactions to occur, evacuated to 40 millimeters (mm) Hg, and impregnated with a styreneacrylonitrile comonomer, which gives the highest strength after polymerization. Positive pressure of 0.6 N/mm2 was applied and thermal catalytic polymerization was carried out. Optimum initiator concentration was found to be 2 percent. Strength (compressive and tensile) increases with polymerization temperature up to 120°C, above which rapid deterioration occurs due to monomer loss, production of short chains with high polymerization rates, and the possibility of polymer degradation at high temperature. Optimum polymerization period of' 10 hours was selected. Inexpensive methods for field polymerization were tried at 95°C. Hot water yields a strength more than double that obtained with a, flow of hot air and about 80 percent of that obtained radiolytically. While hot air accelerates evaporation, hot water forms a hydraulic head above the capillaries and decreases the monomer losses tremendously.
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  • 177
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    Notes: The absorption of water vapor by propellants based on hydroxy-terminated polybutadiene and an isocyanate from atmospheres of increasing relative humidities, and the swelling index of the propellant which had absorbed various proportions of water, were measured in an attempt to establish the extent of hydrolytic damage. The method was found incapable of assessing such damage, but it was shown that there was no measurable absorption of vapor below 92 percent relative humidity (RH). The MEK/polymer and toluene/polymer interaction parameters were determined.
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    Polymer Engineering and Science 24 (1984), S. 673-685 
    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: The hierarchy of mathematical models of injection molding is reviewed. Compatibility of the models of the hierarchy, usefulness of simultaneous applications of models formulated on several different levels of the hierarchy and compatability between physical approximations leading to the formulation of a model, and mathematical approximations used to solve numerically the governing equations of the model are discussed. This review is intended to facilitate the search for a model that is best suited to a given need and to indicate future research.
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    Polymer Engineering and Science 24 (1984), S. 716-721 
    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
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  • 180
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    Polymer Engineering and Science 24 (1984), S. 737-749 
    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 paper discusses some new mechanical and small angle neutron scattering (SANS) data on glassy polymers, both thermoplastics and thermoset resins, from the point of view of dislocation-like defects introduced in the molecular chain arrangement by deformation. In the pre-yield stage, a new parameter, the work-hardening rate K is introduced and its measurement is defined. Experiments are reported which show that K can be used as a very sensitive probe for microstructural changes during physical aging or curing. In one hand, the theory of yielding is revisited to make clear how dislocations and their propagation in polymers depend on specific features like entanglements and chain stiffness. On this basis, experimental internal stresses and activation volumes at yield (i.e., the temperature slope of yield stress) are accounted for. On the other hand, SANS data provide us with experimental evidence at the scale of 10 to 20 Å of the dislocation nature of the molecular “shear defects” introduced in the polymer by deformation. Finally, temperature is known to have a pronounced influence on yield processes. It is shown that two distinct deformation modes exist below and above a critical temperature Tc. Above Tc, a dislocation climb, which probably involves β-processes, gives rise to a “diffusional” deformation mode where chains within a (diffuse) shear band are no longer oriented. A tentative formalization of this behavior, and its relation to the small strain creep of polymers, are then presented.
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    Polymer Engineering and Science 24 (1984), S. 724-736 
    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: The deformation behavior of three polymers, polyethylene terephthalate (PET), polymethylmethacrylate (PMMA), and linear polyethylene (LPE) is considered in terms of two key factors, the stretching of a molecular network and the influence of thermally activated processes. In PET the observation of a natural draw ratio leads to studies of shrinkage, shrinkage force, and optical birefringence to define the nature of the network. The network is further exemplified by measurements of the molecular reorientation in deformation bands, spectroscopic studies of molecular orientation in drawing, and the concept of a true stress-strain curve. Yield and plastic deformation are also to be considered as thermally activated processes, but it appears that a major part of the flow stress is associated with the stretching of the molecular network. In PMMA the concept of a true stress strain curve also appears to be valuable, but the possibility of network breakdown during deformation has to be admitted as an extra complexity. In LPE the concept of a molecular network embracing both crystalline and non-crystalline material is helpful in understanding the drawing behavior. There is also direct evidence for the existence of a network from measurements of shrinkage and shrinkage force, and the existence of a true-stress strain curve. However, the dominant contribution to the flow stress now appears to come from thermally activated processes, with a key contribution from a small activation volume process which is tentatively associated with slip in the crystalline regions.
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  • 182
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    Polymer Engineering and Science 24 (1984), S. 886-894 
    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: Internal friction has been measured by torsion at 1 Hz during tensile tests performed on glassy polycarbonate at room-temperature. Steady-state flow and transient effects have been studied during continuous tensile tests and strain-rate changes. During steady-state, internal friction and flow-stress vary in a similar way with strain-rate. But during transients, internal friction varies continuously while flow-stress passes through a maximum (or a minimum). These results are interpreted assuming that non-elastic deformation of glassy polymers requires some microscopic discontinuous processes such as motion of defects. Two parameters are considered: the velocity v and the density ρ of mobile defects. Assuming that the former is directly related to the flow stress, it has been shown that internal friction is related to the density of mobile defects ρ. This feature is used to interpret the different stages of a tensile test curve. Activation volumes for both velocity and density of mobile defects are calculated from experimental data.
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  • 183
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    Polymer Engineering and Science 24 (1984), S. 915-920 
    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: The molecular kinetic theory near the glass transition, bused on the existence of free volume distribution, is extended to incorporate the effects of stress and stress rate. The fundamental equations for the volume relaxation and recovery in stressed amorphous polymers are derived in accordance with the balance of nonequilibrium statistical entropy. Using these kinetic equations, an earlier nonequilibrium criterion for the glass transition temperature, Tg, is generalized to include the effects of stress and stress rate. In contrast to the prevalent thinking toward free volume theories, an explicit expression between Tg and stress is developed and reveals that Tg does not continue to increase at all pressures but levels off to a “universal” asymptote at very high pressure (〉10 K bars). The expression is applicable to any tension and compression stress conditions. A comparison between theory and experiment under constant stresses determines the activation volume tensor which reveals the molecular mechanism relating Tg and the plastic yield of glassy polymers.
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  • 184
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    Notes: Paper properties of the thermochemical pulp modified by ozonation and grafting with styrene, acrylamide or their mixtures have been studied. Paper sheets, prepared by hot pressing from ozonated and grafted pulps showed improvement in: wet breaking length; dry breaking length; burst and dimensional stability.
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    Polymer Engineering and Science 24 (1984), S. 608-611 
    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: A commercial polyarylate (PAr), a copolyester of Bisphenol-A with 50 percent terephthalate-50 percent isophthalate, has been characterized by means of a combination of gel permeation chromatography and viscometry. It has been studied as first component of a series of polymer blends. The presence of either one glass transition temperature (Tg) or two has been used as a criterion to determine the miscibility of each blend. In some cases, the possible incidence of transesterification reactions has been considered.
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    Polymer Engineering and Science 24 (1984), S. 624-625 
    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
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  • 187
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    Polymer Engineering and Science 24 (1984), S. 645-651 
    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: The residence time distribution (RTD) in a fully intermeshing, corotating twin screw extruder was determined with a stimulus-response technique. In addition to varying three process parameters (i.e. throughput, screw rotational speed, and barrel temperature), two screw configurations were also studied: one containing four kneading block mixing sections, and the other consisting only of regular screw bushings. Although screw configuration was an important variable, it was found that for both configurations the throughput had the largest effect on RTD. The screw rotational speed was second in importance, and the barrel temperature change produced no effect.A fluid mechanical model based on the fluid flow in a partially-filled rectangular channel was used to explain the experimentally observed dependence of RTD on the process parameters. Reaction engineering approaches were adopted to compare the RTD results of two screw configurations with two idealized flows.
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    Polymer Engineering and Science 24 (1984), S. 686-691 
    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: Some aspects of injection-molding dynamics were studied using a laboratory injection-molding machine operated under the control of a microprocessor-based servocontrol system. Two types of experiments were performed: deterministic tests which introduced step changes in the servovalve opening and stochastic tests using pseudo-random binary sequence (PRBS) perturbations of the servovalve. Deterministic models were written for the hydraulic and nozzle pressures which were in good agreement with the experimental data. A stochastic transfer function-noise model was obtained for the nozzle pressure, but an adequate model was not found for the hydraulic pressure. The agreement between the nozzle pressure stochastic model and the corresponding step test model was satisfactory.
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    Polymer Engineering and Science 24 (1984), S. 707-715 
    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: A general-purpose finite element program has been used to simulate the flow of Newtonian, power-law, and viscoelastic fluids in the entry and exit regions of a slit die. It was found that shear-thinning increases the entrance correction while it decreases the exit correction. Shear-thinning reduces the size of the small corner vortex that forms in the entry flow of a Newtonian fluid. The swelling ratio had a value of 1.196 for Newtonian fluids and decreased as the value of the power-law index decreased. Viscoelastic calculations were performed using the Criminale-Ericksen-Filbey (CEF) constitutive equation. Convergence of the iterative scheme was unattainable for Deborah numbers above 1.0. The results showed a decrease of the entrance correction and an increase of the exit correction with elasticity. Extrudate swell first decreased slightly and further increased with the Deborah number.
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    Polymer Engineering and Science 24 (1984), S. 761-769 
    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: As crazes grow in areal extent they also increase in width. The areal growth involves craze tip advance which has been shown to occur by the Taylor meniscus instability. Craze widening, at least for air crazes, occurs by drawing more fibrillar material from the craze-bulk polymer interfaces at essentially constant extension ratio. Simple arguments will be given to predict the scale of the fibrillation in terms of the stress S at the craze tip and interfaces and an effective polymer surface energy (Γ) where:\documentclass{article}\pagestyle{empty}\begin{document}$$ {\Gamma = \gamma + {\raise0.5ex\hbox{$\scriptstyle 1$}\kern-0.1em/\kern-0.15em\lower0.25ex\hbox{$\scriptstyle 4$}}d \cdot v_E U_b} $$\end{document} which assumes that all entangled chain crossing the surface are broken [γ represents the van-der-Waals (intermolecular) surface energy, d is the entanglement mesh size, vE is the entanglement density, and Ub is the energy required to break a single backbone bond]. These arguments also give the rate of fibrillation as a function of S, a nominal plastic resistance σy and Γ and can explain the fact that the stress for crazing increases relative to that for shear deformation as the entanglement density of the polymer is increased. The geometrically necessary entanglement loss (either by scission as assumed above or by disentanglement- at temperatures just below Tg) that accompanies fibril formation has important consequences for fibril stability. The probability p that a given entangled chain is lost can be computed from simple geometrical considerations knowing the fibril diameter D, its extension ratio λ and the mesh size d; p increases rapidly as Dλ½ becomes comparable to or less than d. These concepts can be tested in blends of high molecular weight polymer with chains of the same polymer that are too short to entangle.
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    Polymer Engineering and Science 24 (1984), S. 1174-1179 
    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: Critical strains causing environmental stress cracking of injection-molded poly(acrylonitrile-butadiene-styrene) (ABS) and poly(styrene-acrylonitrile) (SAN) plaques were determined upon exposure to methanol. Measurements were obtained for samples strained either parallel or perpendicular to the melt flow direction and for samples located at various distances from the mold gate. Critical strains were significantly higher in the direction parallel to the melt flow compared to the transverse direction. The degree of anisotropy increased with increasing rubber content. For ABS containing 46 percent rubber, the critical strain at one point was determined to be 2.99 percent in the direction of melt flow, but only 0.47 percent in the orthogonal direction. For this material, critical strains determined parallel to the melt flow decreased with distance from the gate; whereas, critical strains for SAN and ABS containing 30 percent rubber remained essentially constant. Orientation of the plaques was assessed using shrinkage determinations and a thermal conductivity technique. Though a straightforward correlation of orientation with critical strain is observed for ABS, a similar relationship is not observed for SAN. These results suggest that although stress cracking occurs in the glassy matrix of ABS, it is the dispersed rubbery phase which controls the magnitude of strain required to initiate cracking.
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    Polymer Engineering and Science 24 (1984), S. 1185-1201 
    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: A basic study of the kinematics, dynamics, and heat transfer occuring during tubular film extrusion of polyethylene is outlined. Three rheologically characterized polyethylenes, a low-density polyethylene (LDPE), a linear-low-density polyethylene (L-LDPE), and a high-density polyethylene (HDPE) were used in this study. The kinematics and stability of the tubular film process were investigated over a wide range of blow-up ratios, drawdown ratios, and frost-line heights. Local deformation rates along the bubble have been determined. Regions of stability and instability are described. Tensions and inflation pressures have been measured and expressed in terms of locol elongational viscosities. Temperature profiles along the bubble were determined and interpreted in terms of local heat transfer coefficients. Positions of crystallization and temperature profiles have been noted and used to estimate rates of crystallization. The characteristics of the LDPE, LLDPE, and HDPE are contrasted.
    Additional Material: 47 Ill.
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  • 193
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984) 
    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
    Type of Medium: Electronic Resource
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  • 194
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1020-1020 
    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
    Type of Medium: Electronic Resource
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  • 195
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1026-1034 
    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: A mathematical analysis of bubble growth in an expanding foam is presented. The analysis is based on a cell model whereby the foam is divided into spherical microscopic unit cells of equal and constant mass, each consisting of a liquid envelope (or shell) and a concentric spherical gas bubble. Expansion occurs by diffusion of a dissolved gas from the supersaturated envelope into the bubble. This cell model is capable of describing important qualitative features of a real system of numerous bubbles growing in close proximity to one another, and is intended as the building block of a global analysis of macroscopic foam expansion. The coupled algebraic and differential equations governing the growth of a cell are derived and solved numerically. Five dimensionless parameters are identified for the case of constant temperature and pressure outside the cell, and their effects are demonstrated through computer simulations of the system. Of these parameters, surface tension and initial radius prove to be of relatively little importance in the practical cases considered. The other parameters are the thermodynamic driving force, the cell mass (inversely proportional to the number density of bubbles), and the ratio of characteristic times for mass and momentum transport.
    Additional Material: 7 Ill.
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  • 196
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1277-1282 
    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 paper outlines the development of an acoustical technique for measuring the dispersion of an additive in a polymer melt. It included a justification of the use of sound over other interrogating methods and an analysis of the acoustical system's operation. Results for dispersions of liquid or solid additives were shown. It was demonstrated that this system could detect the presence or absence of large particles in melts filled with small particles.
    Additional Material: 15 Ill.
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  • 197
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984) 
    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
    Type of Medium: Electronic Resource
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  • 198
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    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 24 (1984), S. 1284-1290 
    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: We discuss the free-energy expressions for homogeneous melts and their blends, based on our hole theory. Equation of state (PVT) and free energy of mixing (ΔGm) are considered from a common point of view without the introduction of additional parameters to pass from the first to the second set of properties. Practical problems arise from the fact that ΔGm represents a difference between large quantities. As illustrations we analyze two typical systems. One is the n - C6 + n - C16 pair where PVT and ΔGm, the latter at atmospheric pressure only, have been studied experimentally. The other is n - C6 with a low and high molecular weight respectively of polyethylene as solute. Here the PVT relations of the components only are known. The effects of intercomponent attractions, temperature, pressure, and molecular weight on phase behavior are investigated. Critical coordinates, lower critical-solution temperatures (LCST) and their pressure dependence are computed. An iso-free volume condition obtains for this dependence where free volume is defined by the hole fraction inherent in the theory. Comparisons with experimental observations and other theoretical computations for different molecular weights are limited by the effect of polydispersity. Moreover, cloud point curves are shown. We finally compute the composition and pressure dependence of the χ-parameter which is implicit in the theory. We conclude with some comments regarding polymer blends.
    Additional Material: 6 Ill.
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  • 199
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    Polymer Engineering and Science 24 (1984), S. 1312-1318 
    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: Blends of polycarbonate/polystyrene (PC/PS), polycarbonate/polypropylene (PC/PP) and ternary blends of the three components (PC/PS/PP) were studied. Extrudate swell of the molten blends increased with increasing concentrations of the minor components and leveled off at characteristic blend compositions. These compositions corresponded to the limits of compatibility as judged by the onset of brittleness in tensile tests. Both PS and PP appear to have some limited practical compatibility with PC. The change in extrudate swell behavior with concentration may be a rapid and convenient test for the effective concentration limits of partially miscible polymers.
    Additional Material: 17 Ill.
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  • 200
    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: An experimental study of the development of phase morphology in incompatible polymer melt blends of polyethylene/polystyrene (PE/PS), polyethylene/polycarbonate (PE/PC), and polyethylene/nylon-6 (PE/N6) is presented. Different temperatures (180°C, 240°C) of mixing and polyethylene molecular- weight levels were used in the PE/PS studies. Little variation in the cross-sectional phase morphology of the PE/PS extrudates was observed with these variables, though the morphology became finer with increased shear rate/stress in capillary die flow. Variations in the longitudinal morphology are observed with continuous filaments of dispersed phase only arising when the dispersed phase has an equal or lower viscosity than the continuous phase. The PE/N6 and PE/PC, especially the former, give coarser morphologies when the N6 and PC are the continuous phases. This was attributed to larger inter-facial tensions. The effect of viscoelasticity was also discussed.
    Additional Material: 24 Ill.
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