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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 7 (1971), S. 150-162 
    ISSN: 1432-0827
    Schlagwort(e): Uranium ; Bone ; Distribution ; Fission ; Chemistry
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé Une concentration moyenne de 2.4×10−8 g U/g de cendre a été obtenue à partir de l'os humain normal. La microdistribution de l'uranium dans l'os indique que cet élément est surtout limité à surface de l'endoste et, en particulier, aux surfaces de l'os lamellaire et aux parois des canaux de Havers, ouverts dans l'os corticol. Cette répartition suggère que l'uranium se présente sous une forme chimique impropre à son incorporation dans l'apatite osseux: il ne semble donc pas exister une distribution diffuse significative de l'uranium dans l'os.
    Kurzfassung: Zusammenfassung Eine mittlere Konzentration von 2,4×10−8 g Uran/g Asche wurde in normalen menschlichen Knochen gefunden. Die Feinverteilung von Uran im Knochen zeigt, daß dieses Element hauptsächlich an der endostalen Oberfläche vorkommt, insbesondere an der Oberfläche des trabeculären Knochens und an den Wänden der offenen Haversschen Kanäle im kortikalen Knochen. Diese Verteilung läßt vermuten, daß Uran in einer chemischen Form vorliegt, welche sich für den Einbau in das Knochenapatit nicht eignet. Daraus folgt, daß keine signifikante diffuse Verteilung des Urans innerhalb des Knochens vorliegt.
    Notizen: Abstract A mean concentration of 2.4×10−8 g U/g ash has been obtained for normal human bone The microdistribution of uranium in bone indicates that this element is mainly restricted to endosteal surfaces; in particular the surfaces of trabecular bone and the walls of open Haversian canals in cortical bone. This distribution suggests that uranium is present in a chemical form that is not acceptable for incorporation into bone apatite and consequently there does not appear to be a significant diffuse distribution of uranium throughout bone.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 8 (1971), S. 54-72 
    ISSN: 1432-0827
    Schlagwort(e): Morphology ; Glycosaminoglycans ; Cartilage ; Chemistry ; Audioradiography ; Healing
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé Une perte de substance ostéo-cartilagineuse, de taille limitée et identique, est réalisée chez le lapin adulte et la cicatrisation est étudiée histologiquement et par autoradiographie après marquagein vitro au35S-sulfate. Une analyse microchimique est pratiquée pour le contenu et la composition en glycosaminoglycanes. 1. Entre la première semaine et la 4ème et 8ème semaine, un tissu conjonctif non-métachromatique se différencie en un cartilage métachromatique et la quantité de sulfate de chondroitine augmente de façon significative aux dépens des glycoprotéines. 2. Jusqu'à la 4ème semaine, la perte de substance est surtout comblée par de l'os néoformé: après cette période, la région est comblée au delà de la limite de la surface articulaire. 3. Le cartilage hyalin, ressemblant morphologiquement, autoradiographiquement et chimiquement au cartilage articulaire, en ce qui concerne la distribution en glycosaminoglycanes, constitute la surface articulaire de la perte de substance comblée dans un tiers des cas après 8 semaines. Le cartilage hyalin s'observe surtout dans les régions où de l'os néoformé a comblé la cavité médullaire. 4. Dans les deux tiers des cas, après 8 semaines, les surfaces articulaires des zones comblées comportent, non seulement du cartilage, mais aussi du tissu fibreux se formant essentiellement sur les parties latérales et dans les régions, où la cavité médullaire, fliant face, à la surface articulaire, n'a pas été comblée par du tissue osseux. La fraction glycoprotéique augmente par rapport à la fraction chondroitine sulfate. 5. Dans la majorité des cas, après 20 semaines, le cartilage néoformé subit des phénomènes dégénératifs, qui se traduisent par une diminution en chondroitine sulfate.
    Kurzfassung: Zusammenfassung Bei ausgewachsenen Kaninchen wurde ein begrenzter, standardisierter, osteochondraler Defekt hervorgerufen, und das regenerierte Gewebe wurde histologisch und autoradiographisch durch Markierung in vitro mit35S-Sulfat und durch mikrochemische Bestimmung des Gehaltes und der Zusammensetzung der Glykosaminglykane untersucht. Die wichtigsten Befunde waren: 1. Zwischen 1 und 4–8 Wochen veränderte sich nichtmetachromatisches Bindegewebe zu metachromatisch gefärbtem Knorpel, und der Anteil an Chondroitin-Sulfat nahm auf Kosten der Glykoproteine signifikant zu. 2. Bis zu 4 Wochen war der Hauptteil des defekten Gebietes mit neugebildetem Knochen gefüllt; nach dieser Zeit lag dieser Bezirk oberhalb der Verknöcherungsgrenze in Richtung der Gelenkoberfläche. 3. Nach 8 Wochen bestand die Gelenkoberfläche des defekten Gebietes in einem Drittel der Fälle aus hyalinem Knorpel, der morphologisch, autoradiographisch und chemisch dem Gelenkknorpel in Bezug auf die Verteilung von Glykosaminoglykanen glich. Hyaliner Knorpel wurde hauptsächlich an Stellen beobachtet, wo neugebildeter Knochen die Markhöhle geschlossen hatte. 3. Nach 8 Wochen bestand die Gelenkoberfläche des defekten Gebietes in einem Drittel der Fälle aus hyalinem Knorpel, der morphologisch, autoradiographisch und chemisch dem Gelenkknorpel in Bezug auf die Verteilung von Glykosaminoglykanen glich. Hyaliner Knorpel wurde hauptsächlich an Stellen beobachtet, wo neugebildeter Knochen die Markhöhle geschlossen hatte. 4. Nach 8 Wochen bestanden Teile der Gelenkoberfläche des Defektes in zwei Dritteln der Fälle nicht nur aus Knorpel, sondern auch aus fibrösem Gewebe, welches vor allem in den seitlichen Teilen des Defektes und an Stellen vorlag, wo die Markhöhle gegenüber der Gelenkoberfläche nicht mit Knochengewebe verschlossen worden war. Die Glykoproteinfraktion nahm im Vergleich zur Chondroitin-Sulfatfraktion zu. 5. Nach 20 Wochen zeigten sich in den meisten Fällen bei neugebildetem Knorpel degenerative Veränderungen, welche durch eine gewisse Abnahme des Chondroitin-Sulfats wiedergegeben wurden.
    Notizen: Abstract A limited, standardized osteochondral defect was created in adult rabbits and the regenerated tissue was examined histologically and autoradiographically after labellingin vitro with35S-sulphate, and microchemically for its content and composition of glycosaminoglycans. The principal findings were: 1. Between 1 week and 4 to 8 weeks, non-metachromatic connective tissue differentiated to metachromatically stained cartilage, and the proportion of the chondroitin sulphate increased significantly at the expense of the glycoproteins. 2. Up to 4 weeks, the major part of the defect area was filled with newly formed bone; after this time, the area lay above the level of the “tidemark”, towards the articular surface. 3. Hyaline cartilage with morphological, autoradiographic and chemical resemblance to the articular cartilage in terms of the distribution of glycosaminoglycans constituted the articular surface of the defect area in one-third of the cases at observation times after 8 weeks. Hyaline cartilage was observed mainly in areas where newly formed bone had closed the medullary cavity. 4. In two-thirds of the cases, after 8 weeks, parts of the articular surface of the defect consisted not only of cartilage but also of fibrous tissue, occurring mainly in the lateral parts of the defect and in areas where the medullary cavity facing the articular surface had not been sealed by bone tissue. The glycoprotein fraction increased relative to the chondroitin sulphate fraction. 5. In most cases after 20 weeks, newly-formed cartilage underwent degenerative changes, which were reflected in some reduction of the chondroitin sulphate.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 8 (1971), S. 165-171 
    ISSN: 1432-0827
    Schlagwort(e): Bone ; Ceramic ; Tetracycline ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé Un implant céramique non poreux est testé au niveau du fémur de rat en ce qui concerne son adhésivité à l'os. Un certain nombre de techniques morphologiques sont utilisées pour examiner le rapport entre l'implant et l'os néoformé. La microscopie électronique par transmission et la microscopie par fluorescence après marquage à la tétracycline ont donné les meilleurs résultats. Un rapport étroit entre l'os minéralisé et la céramique a été noté en microscopie électronique. Par marquage à la tétracycline, il semble que l'implant puisse stimuler la formation osseuse.
    Kurzfassung: Zusammenfassung Ein unporöses keramisches Implantat in Rattenfemora wurde auf seine Fähigkeit geprüft, sich mit Knochen zu binden. Eine Anzahl morphologischer Techniken wurde verwendet, um die Beziehung zwischen den Oberflächen von Implantat und neuem Knochen zu untersuchen. Transmissions-Elektronenmikroskopie und Fluoreszenzmikroskopie nach Tetracyclinmarkierung waren die erfolgreichsten Techniken. Eine enge Beziehung zwischen mineralisiertem Knochen und dem Keramikimplantat konnte mit der Transmissions-Elektronenmikroskopie nachgewiesen werden. Das Aussehen der Tetracyclinmarkierung im keramischen Implantat deutet darauf hin, daß dieses wahrscheinlich die Fähighkeit hat, Knochenbildung zu erhöhen.
    Notizen: Abstract A nonporous ceramic implant in rat femora was evaluated as to its ability to bond to bone. A number of morphologic techniques were utilized to examine the interfacial relationship of the implant to new bone. Transmission electron microscopy and fluorescence microscopy after tetracycline labelling were the most successful techniques. An intimate relationship between mineralized bone and the ceramic was demonstrated by transmission electron microscopy. The appearance of tetracycline labelling at the ceramic interface indicates that the implant may have capacity to enhance bone formation.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 8 (1971), S. 228-236 
    ISSN: 1432-0827
    Schlagwort(e): Skin ; Calcinosis ; Keratin ; Chemistry ; X-ray diffraction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé Des études histologiques antérieures ont montré que le follicle pileux est particulièrement susceptible de se calcifier, lorsque la peau de rats hypercalcémiques est lésée. Des analyses chimiques et par diffraction aux rayons X du follicule ont confirmé ce résultat. — En se basant sur l'augmentation du calcium et du phosphore, les calcifications débutent dans le tissue folliculaire 6–12 h après une blessure d'intensité moyenne de la peau de rats, ayant reçu du dihydrotachysterol (DHT), et 24–48 h après une blessure similaire chez des rats non injectés. Les diagrammes de diffraction aux rayons X sont diffus. Trois heures après la blessure, on note une augmentation du calcium du tissu folliculaire qui ne semble pas en rapport avec le DHT qui traduit probablement une liaison de calcium plutôt qu'un dépot minéral.
    Kurzfassung: Zusammenfassung Frühere histologische Untersuchungen haben gezeigt, daß der Haarfollikel besonders anfällig für Verkalkungen ist, wenn die Haut von hypercalcämischen Ratten verletzt wird. Dieses Resultat wurde nun durch direkte chemische Bestimmungen und Röntgendiffraktions-analysen von Follikelgewebe bestätigt. Aufgrund der erhöhten Calcium- und Phosphatwerte kann gesagt werden, daß nach einer leichten Quetschung der Haut von Ratten, die mit Dihydrotachysterol (DHT) behandelt wurden, im Haarfollikelgewebe nach 6–12 Std Mineral-ablagerungen stattfanden, wogegen Kontrollratten mit der gleichen leichten Hautverletzung diese Ablagerungen erst nach 24–48 Std zeigten. Röntgendiffraktionsanalysen ergaben ein diffuses Apatit-Muster. Innerhalb 3 Std nach der Verletzung wurde ein Anstieg des Calcium-gehaltes im Follikelgewebe beobachtet, der nicht im Zusammenhang mit der DHT-Behandlung stand, also nicht eine Mineralablagerung, sondern eher eine Bindung von Calcium widerspiegelte.
    Notizen: Abstract Previous histological investigations have shown that the hair follicle is particularly susceptible to mineralization when the skin of hypercalcaemic rats is injured. Direct chemical and X-ray diffraction analyses of follicle tissue have now confirmed this finding. As judged by increases in both calcium and phosphorus, mineral deposits began to form in hair follicle tissue 6–12 h after a mild crush injury to the skin of rats dosed with dihydrotachysterol (DHT), and 24–48 h after a similar injury to the skin of non-dosed rats. X-ray diffraction gave a diffuse apatite pattern. Within 3 h of injury there was a rise in the calcium content of follicle tissue which was not related to DHT-dosing and which was probably a reflection of calcium binding rather than mineral deposition.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 8 (1971), S. 304-319 
    ISSN: 1432-0827
    Schlagwort(e): Chemistry ; Calcium ; Phosphate ; Solubility ; Computer
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé Un programme d'ordinateur a été mis au point pour calculer les activités ioniques du calcium et l'orthophosphate dans un grand nombre de solutions. Dans le cas de solutions synthétiques, les calculs sont vérifiés en comparant les valeurs de pH, obtenues par ordinateur, avec celles observées expérimentalement. Des essais de ce type, avec des solutions possèdant des concentrations de calcium et d'orthophosphate trouvées dans les liquides biologiques et à des valeurs de pH variant de 3.00 à 10.00, indiquent que le programme est adapté pour des applications biologiques. Le programme n'est pas effectif pour des solutions, dans les lesquelles l'ion bromure est la source principale de la force ionique, sans doute, par manque d'équation étendue de Debye-Hückel dans ces circonstances. Aucune formation de complexe de phosphate de sodium n'a été notée à des concentrations biologiques normales.
    Kurzfassung: Zusammenfassung Es wurde ein Computer-Programm ausgearbeitet, um die Ionenaktivitäten von Calcium und Orthophosphat in einer breiten Varietät von Lösungen zu berechnen. Die Berechnungen wurden bei synthetischen Lösungen durch Vergleiche zwischen den auf diese Weise errechneten pH-Werten und den experimentell gefundenen kontrolliert. Diese Art Kontrollen mit Calcium-und Orthophosphatkonzentrationen, wie sie in biologischen Flüssigkeiten gefunden werden, und mit pH-Werten zwischen 3,0 und 10,0 wies darauf hin, daß das Programm für biologische Anwendungen geeignet war. Das Programm konnte nicht benützt werden für solche Lösungen, bei welchen hauptsächlich das Bromidion zur Einstellung der Ionenstärke verwendet wurde, vermutlich weil die erweiterte Debye-Hückel-Gleichung unter diesen Umständen nicht anwendbar ist. Die Bildung eines Natriumphosphat-Komplexes unter normalen biologischen Konzentrationen konnte nicht nachgewiesen werden.
    Notizen: Abstract A computer program has been designed to calculate the ionic activities of calcium and orthophosphate in a wide variety of solutions. In the case of synthetic solutions the calculations were checked by comparing the computed pH values with those observed experimentally. Tests of this type with solutions having the concentrations of calcium and orthophosphate found in biological fluids and with pH values ranging from pH 3.0–10.0 indicated that the program was suitable for biological applications. The program was not effective for solutions in which the bromide ion was a principal source of ionic strength probably because of the failure of the extended Debye-Hückel equation under those circumstances. No evidence for the formation of any sodium phosphate complex at normal biological concentrations could be found.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 8 (1971), S. 197-210 
    ISSN: 1432-0827
    Schlagwort(e): Fluorescence ; Calcium ; Collagen ; Chemistry ; Bone ; Dentine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé Des composants fluorescents de l'os et la dentine sont séparés des hydrolysats alcalins de leur marice sur des colonnes Sephadex C25 CM d'échange cationique. Les concentrations en fluorescence et le spectre d'excitation (λ max 330 nm) et d'émission (λ max 395 nm) sont les mêmes que ceux observés au niveau des matrices intactes et gélatinisées. Les paramètres de fluorescence ne sont pas altérés par hydrolyse. La filtration sur gel à l'aide de colonnes Sephadex G 10 perment de différencier le matériel isolé en deux composants, ayant la même fluorescence et la même absorption UV. La fluorescence est indépendante de pH de 3.5–9.5. Des études de dialyse et de filtration sur gel de matrices gélatinisées indiquent une association étroite du matériel fluorescent avec les chaines polypeptidiques de collagène.
    Kurzfassung: Zusammenfassung Fluorescierende Bestandteile aus Knochen und Dentin wurden in Sephadex C25 CM Kationen-Austauschersäulen von alkalischen Hydrolysaten ihrer Matrices getrennt. Die Fluorescenzintensitäten sowie die Erregungs- (λ max 330 nm) und Emissions- (λ max 395 nm) Spektren waren dieselben wie bei intakten und gelatinisierten Matrices. Die Fluorescenzparameter wurden durch die Hydrolyse nicht verändert. Eine Gelfiltration über Sephadex-G10-Säulen trennte das isolierte Material in 2 Komponenten auf, welche gleiche Fluorescenz- und UV-Absorptionseigenschaften zeigten. Im pH-Bereich zwischen 3,5 und 9,5 war die Fluorescenz unabhängig vom pH. Dialysierversuche sowie Gelfiltrationsexperimente mitden gelatinisierten Matrices zeigten eine starkgefügte Bindung des fluorescierenden Materials mit den Polypeptidketten des Kollagens.
    Notizen: Abstract Fluorescent components in bone and dentine were separated from alkaline hydrolysates of their matrices on Sephadex C25 CM cationic exchange columns. The fluorescence levels, and the excitation (λ max 330 nm) and emission (λ max 395 nm) spectra, were the same as those observed in the intact and gelatinised matrices. The fluorescence parameters were unaltered by the hydrolysis procedure. Gel filtration on Sephadex G. 10 columns further resolved the isolated material into two components with the same fluorescence and UV absorption properties. The fluorescence was independent of pH over the range 3.5–9.5. Dialysis and gel filtration studies on the gelatinised matrices indicated a firmly-bonded association of the fluorescent material with the collagen polypeptide chains.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Calcified tissue international 8 (1971), S. 287-303 
    ISSN: 1432-0827
    Schlagwort(e): Calcification ; Bone ; Matrix ; Apatite ; Nucleation ; Electron microscopy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Physik
    Beschreibung / Inhaltsverzeichnis: Résumé Du collagène d'os compact de mouton est préparé par décalcification dans I'EDTA et à partir de tendons de queux de rats, par extraction dans l'acide acétique et reconstitution dans NaCl. Le dépôt d'apatite dans le collagène osseux de mouton dans une solution de calcification métastable est étudié chimiquement et par microscopie électronique. Le collagène osseux est un bon catalyseur de nucléation pour le dépôt minéral, alors que le collagène de tendons de rat ne l'est pas. Le dépôt minéral du collagène osseux se produit en deux phases cinétiques séparées, une phase rapide de nucléation et une croissance cristalline, donnant naissance à de petits ilots calcifiés et une seconde phase lente de croissance dans des régions ne comportant pas de zones catalytiques. La seconde phase de dépôt minéral paraît être le résultat d'une diffusion inhibée d'ions à travers les fibrilles collagènes alignées, laissant de larges régions de collagène sans minéral, bien que le tampon reste hautement sursaturé. La microscopie électronique permet de penser que les zones de catalyse pourraient avoir un rapport avec la périodicité de 640 Å de collagène, mais l'importance d'un matériel noncollagènique, lié au collagène, n'est pas à exclure. L'activité catalytique faible du collagène reconstitué n'est pas liée à la présence d'inhibiteurs faiblement liés, bien que des inhibiteurs puissent être intimement liés à ce type de collagène, qui pourrait être absent du collagène osseux. La différence d'activité catalytique pourrait intervenir dans la calcification physiologique. Une hypothèse plus générale pour la nucléation de la phase minérale dans les systémes biologiques est nécessaire.
    Kurzfassung: Zusammenfassung Kollagen wurde aus kompaktem Schafsknochen mittels EDTA-Entkalkung und aus Rattenschwanzsehnen durch Essigsäureextraktion und Rekonstitution mit NaCl gewonnen. Die Apatitablagerung aus einer metastabilen Verkalkungslösung auf Schafsknochenkollagen wurde chemisch und im Elektronenmikroskop untersucht. Es zeigte sich, daß das Knochenkollagen ein guter Nukleationskatalysator für die Mineralablagerung ist, was beim Rattenschwanzkollagen nicht zutraf. Im Knochenkollagen erfolgte die Mineralablagerung in zwei getrennten kinetischen Phasen: einer raschen Phase der Nukleation und des Kristallwachstums, welche kleine verkalkte Inseln entstehen läßt, und einer zweiten langsamen Phase, welcher das Wachstum in Bezierken, die keine katalytischaktiven Stellen einschließen, zuzuschreiben ist. Diese zweite Phase der Mineralablagerung wird als Resultat einer verminderten Ionendiffusion durch die enganeinanderliegenden Kollagenfibrillen angesehen, wodurch weite Kollagenbereiche ohne Mineral bleiben, obwohl der Puffer stark übersättigt ist. Elektronenmikrographien ließen vermuten, daß die katalytischaktiven Stellen in einem gewissen Verhältnis zur 640 Å-Periodizität des Kollagens stehen; es konnte jedoch nicht ausgeschlossen werden, daß nicht-kollagenhaltiges Material, welches an Kollagen gebunden ist, ebenfalls eine Rolle spielt. Die schlechte katalytische Aktivität des rekonstituierten Kollagens konnte nicht auf die Anwesenheit von schwachgebundenen Hemmstoffen zurückgeführt werden, obwohl Inhibitoren stark an dieses Kollagen gebunden sein könnten, die jedoch im Knochenkollagen nicht vorhanden sind. Die Unterschiede in der katalytischen Aktivität können mit der physiologischen Verkalkung in Beziehung stehen. Eine allgemeinere Hypothese für die Nukleation einer Mineralphase in biologischen Systemen wäre erforderlich.
    Notizen: Abstract Collagen was prepared from compact sheep bone by decalcification with EDTA and from rat tail tendons by acetic acid extraction and reconstitution with NaCl. The deposition of apatite in sheep bone collagen in a metastable calcification solution was studied chemically and by electron microscopy. The bone collagen was shown to be a good nucleation catalyst for mineral deposition, while rat tail collagen was a poor catalyst. Mineral deposition in bone collagen occured in two separate kinetic phases, a rapid phase of nucleation and crystal growth, giving rise to small calcified islands, and a second slow phase, ascribed to growth in regions not involving the catalytic sites. This second phase of mineral deposition is considered to be the result of impaired ion diffusion through the closely-aligned collagen fibrils, thus leaving large areas of the collagen free of mineral even though the buffer remains highly supersaturated. Electron micrographs suggested that the catalytic sites might be in some relationship to the 640 Å periodicity of collagen, but a role for non-collagenous material bound to the collagen has not been excluded. The poor catalytic activity of reconstituted collagen was not due to the presence of loosely-bound inhibitors, although inhibitors could be strongly bound to this type of collagen and be absent from bone collagen. The differences in catalytic activity may have a bearing on physiological calcification. A more general hypothesis for nucleation of a mineral phase in biological systems is required.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 85-114 
    ISSN: 0449-2978
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Measurements of the small-angle scattering power and the degree of crystallinity in melt-crystallized high-density polyethylene have been used to evaluate the “amorphous” density in situ by the relation, \documentclass{article}\pagestyle{empty}\begin{document}$ (2\pi/V)\int_0^\infty {S\tilde g} (S)dS = (\rho_{\rm c} - \rho_{\rm a})^2 \upsilon_{{\rm er}} (1 - \upsilon_{{\rm er}}) $\end{document} where V is the irradiated volume and ḡ(S) is the “slit-smeared” absolute intensity. The amorphous density is a function of sample history and is always higher than the extrapolated melt density. After slit-height correction, and within the experimental error, the ratio of the two observed long periods is 2:1 at all temperatures (25--126°C). The lamellar thickness and the average interlamellar spacing are obtained from the degree of crystallinity and the first corrected long period. At increasing temperatures between 25°C and 110°C, the lamellae become thinner while the interlamellar zone expands by almost half. Over this range the changes are reversible with temperature. Above 110°C, both the lamellae and the interlamellar region expand with temperature. The thickening is partially reversible upon recooling. Other results obtained include measurements of stacking disorder and of microstructural changes with crystallization temperature and with time at ambient temperature.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 143-160 
    ISSN: 0449-2978
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Work on two sheet organosilicon polymers, one derived from the mineral chrysotile and the other from the mineral apophyllite, is described. This work provides direct evidence that both these polymers are composed of sheets. In addition, it shows that in the chrysotile-derived polymer the sheets curl into scrolls, and that in the apophyllite-derived polymer the sheets are essentially flat.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 209-243 
    ISSN: 0449-2978
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The shear creep and creep recovery behavior of narrow molecular weight distribution polystyrene samples of low molecular weight, 1.1 × 103, 3.4 × 103, and 1.57 × 104 are reported as a function of temperature, near and above the glass temperature. Time-temperature equivalence for the total creep compliance is found to be nonapplicable, and in fact the steady-state recoverable compliance, Je, is a strong function of temperature. The time-scale shift factors for the recoverable compliance are analyzed in the light of free volume theory. Viscosity data are presented for samples with molecular weights between 1.1 × 103 and 6.0 × 105. The temperature dependence of the characteristic time constant ηJe can be explained in terms of free volume concepts whereas that of viscosity η cannot. Effects of residual molecular weight heterogeneity are demonstrated.
    Zusätzliches Material: 18 Ill.
    Materialart: Digitale Medien
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  • 11
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 295-311 
    ISSN: 0449-2978
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A theoretical calculation of the Hv light-scattering patterns for deformed three-dimensional spherulites is presented. Affine deformation is assumed. The optic axis of the scattering element is allowed to lie at an arbitrary angle ß to the radius which is permitted to change in the course of the deformation in a manner that may depend upon the angular location in the spherulite. The consequences of twisting of the optic axis about the spherulite radius are also explored.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 12
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 331-343 
    ISSN: 0449-2978
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The adsorption of polydimethylsiloxane polymers from solution on glass has been studied. The amount of polymer adsorbed depends markedly on the solvent because of specific solvent - surface interactions. The presence of silanol groups in the polymer, particularly as endgroups, markedly increases the amount of polymer adsorbed. Large differences are shown between the adsorption of the commercially available, and fully trimethylsilylated polydimethylsiloxanes of narrow molecular weight distribut on. Possible adsorption mechanisms are discussed.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 13
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 383-384 
    ISSN: 0449-2978
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 14
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 421-430 
    ISSN: 0449-2978
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: A method is given for the analysis of long-chain branching in polymers by using combined GPC and intrinsic viscosity measurements. A computer program was written to evaluate branching indices by a tabular, iterative method. The method was applied to the evaluation of long-chain branching in low-density polyethylene.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 15
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 431-435 
    ISSN: 0449-2978
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The effects of stereoregularity on the low-temperature relaxation processes were studied by dynamic mechanical measurements on isotactic and syndiotactic polyisobutyl methacrylates (iso-PiBMA and syn-PiBMA). The α, β, and γ relaxation processes were observed in both stereoregular forms. Both the α, and β loss peaks were at lower temperatures for iso-PiBMA than for syn-PiBMA. The γ loss peak was observed at about -155°C at 30 Hz for both forms, and the apparent activation energy of this process was same for both samples within experimental error (6.7 ± 0.5 kcal/mole). It was reduced from these results that the α and β processes are both considerably influenced by the isotactic configuration but the γ process is not.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 16
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science: Macromolecular Reviews 5 (1971), S. 385-430 
    ISSN: 0076-2083
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 17
    Digitale Medien
    Digitale Medien
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science: Macromolecular Reviews 5 (1971), S. 431-540 
    ISSN: 0076-2083
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 41 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 18
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 15-26 
    ISSN: 0449-2978
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: The gelation reaction of acetoguanamine with formaldehyde was investigated in the light of the gelation theory for tetrafunctional amino resins described in the previous paper. The gel time and extents of reaction of formaldehyde, amino groups, and imino groups varied with the molar ratio in the feed, but values of K (the ratio of the rate constant for condensation to that for addition) and k (the ratio of the rate constant for addition of the imino group to that of the amino group) were nearly constant. When the catalyst concentration was increased, the gel time, extents of reaction of each functional group, and the values of K and k varied; in particular K increased markedly. From the results of varying the molar ratio and concentration of acidic catalyst, it was found that the number of methylol groups per molecule of acetoguanamine at the gel point was influenced by the reaction conditions but the number of methylene linkages per molecular of acetoguanamine was nearly constant at about 0.6, regardless of reaction conditions. The number-average molecular weights up to the gel point varied with the reaction conditions, but at the gel point they were all nearly constant at about 385.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 19
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 543-555 
    ISSN: 0449-2978
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Photocurrents developed in polyethylene in the wavelength range 360-180 nm have been measured. The action spectra show features which can be related to the corresponding features in the absorption spectrum, and in addition there is electron injection from the metal electrode at a wavelength determined by the electrode material. The time dependence of the response indicates that a long-lived space charge is formed in the material.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 20
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 569-576 
    ISSN: 0449-2978
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Large photocurrents have been observed in films of some simple polymers (containing no π-orbitals), of which poly(vinyl fluoride) is a typical example. Not only are the currents large (up to 10-5 A/cm2) but also they are capable of being excited by light in the visible wavelength region where absorption by the polymer is too low to be detectable. The results indicate that the effects are electronic, rather than ionic, in nature.
    Zusätzliches Material: 4 Tab.
    Materialart: Digitale Medien
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  • 21
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 577-584 
    ISSN: 0449-2978
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: It was previously shown that for a stationary random copolymer of A, B, and C, we have in general p(AB) + p(AC) = p(BA) + p(CA), etc., in place of p(AB) = p(BA) which is valid for a stationary binary copolymer. Here, p(AB) for example, is the probability that a randomly picked pair of consecutive comonomers in the polymer consists of an A followed by a B. For a stationary ternary copolymer produced by a first-order Markovian addition mechanism, we show that PABPBCPCA/PACPCBPBA = k, where k is a constant characteristic of a particular set of three monomers but independent of its composition. Here, PAB is the conditional probability of finding a monomer of B given that its immediate predecessor is an A. We further show that if the individual rate constants of the monomer additions involved take a special form such as used in the Alfrey-Price Q-e scheme, then we have k = 1 irrespective of the kinds of monomers, and in addition we have p(AB) = p(BA), p(AC) = p(CA), etc. Thus, although these latter results were previously proposed by Ham as an alternative basis to supplant the Q-e scheme, they may rather be regarded as mathematical consequences of special assumptions adopted for the form of the individual rate constants. For a stationary random copolymer of four components A, B, C, and D, we have p(AB) + p(AC) + p(AD) = p(BA) + p(CA) + p(DA), etc., in general. For a first-order Markovian four-component copolymer, we show that there are seven different combinations of the conditional probabilities that are constants (k1, k2,…, k1) independent of the monomer composition. Again, if we assume the same special form for the rate constants involved, we find that all the seven constants k1, k2, …, k7 reduce to unity and p(XY) = p(YX) for X,Y, = A, B, C, D.
    Materialart: Digitale Medien
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  • 22
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 9 (1971), S. 717-729 
    ISSN: 0449-2978
    Schlagwort(e): Physics ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Several copolymers as well as homopolymers of vinylidene chloride and vinyl chloride have been examined by Raman spectroscopy. Probabilities of concentrations of monomer sequences have been calculated from known reactivity ratios. Surface scattering intensities at some frequencies were found to be linearly proportional to specific microstructure concentrations. Normalization of scattering intensities was accomplished using the intensity of the CH2 asymmetric stretching mode at 2926 cm-1, which is common to all samples examined. Good correlation was found for the concentrations of comonomer sequences {B}, {BB}, {BBB}, {AA} and {AAAA} in which A denotes vinylidene chloride and B vinyl chloride.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
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  • 23
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 247-250 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 24
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 327-339 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The permeabilities of polyethylene film to vapors of 19 organic compounds at temperatures of 21°C, 38°C, and 49°C were measured by a sorption method. The film was formed into a pouch, which was filled with silica gel, sealed, and suspended in a saturated atmosphere. The permeability was calculated from the steady-state rate of the gain in weight. The permeability data were correlated with the Hildebrand solubility parameters of the organic substances.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 25
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 369-379 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The creeping flow of a highly viscous incompressible fluid through a circular aperture located in an infinitely wide horizontal plate is analyzed by solving Navier-Stokes equations without inertia terms. Solutions for vertical and radial velocities as well as pressure have been obtained in terms of integral equations with an undetermined Kernal function. This function has been evaluated by assuming several different velocity distributions at the aperture, and the corresponding pressure drop for each case has been calculated. The results show that the pressure loss for a given flow rate goes through a minimum as the assumed velocity profile changes from flat to parabolic. Based on the minimum energy dissipation theorem of Helmholtz, the most appropriate velocity distribution is discussed. Experimental data obtained using sharp-edged orifices are compared with theoretical predictions.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 26
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 597-606 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Eastman cellulose acetate membranes (acetyl content = 40%) have been studied by means of dialysis rate experiments with uncharged permeants of selected sizes and shapes. The experimental results show that the high flux membranes exert no molecular size or shape selectivity on the transport of permeants whose molecular weights are less than 1152. The membranes used in desalination, however, are selective as to molecular size and shape. Desalination membranes, therefore, may be useful in separations where differences in size and shape are present.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 27
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 641-659 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The toughness and stress corrosion cracking characteristics of an epoxy resin (DER 332) hardened with hexahydrophthalic anhydride (HHPA) were investigated. The epoxy was studied in both the bulk and bond form, and its properties were compared with an amine-hardened (tetraethylene pentamine, TEPA) system. The toughness, GIc, of the anhydride system varied less as a function of ratio of hardener-to-resin content and postcure temperature than it did in the TEPA-hardened system. Like the latter, however, its toughness in the bulk and bond forms could not be correlated, but GIc of the joints was dependent on tensile modulus and/or yield strength of the bulk epoxy. Both systems were also toughened in the vicinity of the crack tip by water for short-time loading, but their long-time load carrying capability was reduced by a water environment. The anhydride hardened system was more sensitive to strength loss in water than the amine system. The fracture morphology for the two systems was the same, i.e., fast cracking occurred cohesively near the center of the bond, and slow cracking occurred at the interface.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
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  • 28
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 715-729 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The thermal decomposition behavior of rayon yarn which had been treated with various chlorosilanes and boron-phosphorus compounds was determined at temperatures up to 800°C. It was found that 70% of the available hydroxyl groups in rayon would react with dichlorodiphenylsilane and that the treated yarn had an initial decomposition temperature 125°C higher than that of untreated rayon. The weight loss of the treated yarn at 800°C was dependent on the nature of the chlorosilane and the type of posttreatment used. Alkylchlorosilanes produced higher weight losses than did the arylchlorosilane-treated rayons. Treatment of rayon yarn with bis(chlorodiphenyl-phosphine)decaborane (BCDPD) or dimeric chlorophospha(III)-o-carborane (DCPC) resulted in an increase in the char yield of the pyrolyzed yarns. In the case of untreated rayon, weight retention at 800°C was 20%, whereas the treated yarns yielded boronated residues of 42-53%. Carbon yields as high as 28% were obtained with the BCDPD treatment. This treatment also resulted in substantial improvement in the oxidative stability of rayon at temperatures up to 250°C.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
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  • 29
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 747-758 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The effect of N-methyl dithiocarbamate substitution on the radiation stability of poly-(vinyl chloride) (PVC) films was studied. PVC containing between 2 and 11 mole-% N-methyl dithiocarbamate (PMD) was irradiated with γ-rays from a 60Co source at 40°C and the evolved gaseous products were measured and analyzed with a mass spectrometer. The apparent G values for gas evolution for PMD decreased remarkably. For example, a G value of 0.28 was obtained for a PMD which contains 11 mole-% dithiocarbamate group compared with a G value of 10.8 for unmodified poly(vinyl chloride). Furthermore, the mass spectrum of the evolved gas from the same PMD sample (PMD-44) with 10 Mrad irradiation showed no hydrogen chloride to be present. The external protection was studied using polymer-blended films of PVC and PMD-44. The stabilization coefficients for internal protection and external protection in polymer blends were calculated. The ESR spectrum of the irradiated PMD-44 showed a strong anisotropy with high g values which differed significantly from the spectrum of the irradiated PVC. A suggested mechanism for radiation protection of PVC against γ-rays irradiation by the N-methyl dithiocarbamate group is discussed.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 30
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 811-828 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: An attempt has been made to rationalize the variables in the preparation procedure of Loeb-Sourirajan-type reverse-osmosis membranes. The quaternary phase diagram of the system cellulose acetate-acetone-formamide-water was determined and has proved a useful tool in the discussion of membrane structures and properties. A mechanism based on differences in the precipitation rate of the polymer during the membrane formation process has been suggested to explain the observed asymmetry in the membrane structure. The porosity of the membrane has been ascribed to the relative rates of water entering and solvent leaving the cast film. The effects of the casting solution composition, the evaporation time, the wash bath temperature, and the annealing procedure have been studied. X-Ray diffraction and electron microscopy were used to supplement flux and retention data of membranes made from a cellulose acetate-formamide-acetone casting solution.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
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  • 31
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 889-912 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Large sublimed leaflets of titanium trichloride have been observed over a wide range of magnification both by optical and electron microscopy under conditions such that ethylene polymerization was slow enough so that its progress could be observed in detail. After treatment with triethylaluminum, a network of cracks develops on which polymer grows upon introducing ethylene. Polymer also appears on steps, crushed areas, and cleaved edges but not on as-grown edges. The polymer appearing on lateral surfaces was nodular in character while that growing on basal surfaces was fibrous. The physical properties of these two forms may be different, and methods for favoring one or the other are suggested.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
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  • 32
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 403-410 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The inhibitory efficiences of antioxidants (phenols and aromatic amines) were determined under irradiation for elucidation of their behavior in photo-oxidation. We determined the ratio of termination rate constant to propagation rate constant and compared the ratio under irradiation with that in the dark. Phenols are classified into two categories with respect to their behavior under irradiation. The first is as antioxidants that have the same ratios under both conditions; the second, as antioxidants that have smaller ratios under irradiation than in the dark. We assumed the smaller ratios to be due to the following: quinones formed via the excited state of phenols by light absorption, in addition to the original phenols, participate in radical capture. Aromatic amines were also classified into two categories relative to their behavior under irradiation.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
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  • 33
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 419-435 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Cellulose samples modified by iodination, benzhydrylation, and benzhydrylation followed by iodination were pyrolyzed to investigate the potential flame retardance of such treatments. Their effect on crystallinity, rate of thermal degradation, char production, and pyrolysis products was determined. Results indicate that in general the crystallinity index varies inversely with the percentage of substitution, rate of weight loss, and amount of residual char. Although the rates of weight loss of the substituted samples increased from 0.3%/min to 108%/min, depending on the type and percentage of substitution, the overall weight loss pattern of the treated cellulose was similar to that of the untreated samples. Of the three treatments, iodination appears to offer the best flame retardance in that the residual char is increased by a much larger factor for a given weight loss rate. On the other hand, addition of the benzhydryl to the iodinated sample decreases the char. All three treatments drastically reduce the number of degradation products of molecular weights lower than 150; untreated cellulose gave 59 components, whereas the substituted cellulose produced five major compounds: water, acetic acid, furfural, 5-methyl-2-furaldehyde, and 1,5-anhydro-2,3-deoxy-β-D-pent-2-eno-furanose. Of these, water and the furanose derivatives were the major components.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 34
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1365-1375 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: If a low-density polyethylene sheet is treated in a corona discharge and subsequently pressed to a similarly treated sheet at 45°C, the bond formed is much stronger than that between similarly pressed but untreated sheets. Several series of observations have indicated that this enhanced autohesion is not due to surface oxidation or to surface crosslinking (CASING). Evidence is presented that the effect may be related to some type of electret formation induced in the polymer sheet by the corona discharge.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 35
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1231-1235 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: In order to determine the effect of the molecular structure of short side branches in lowdensity polyethylene upon the physical properties of the resin, a study was carried out in which small amounts of various comonomers were added to an otherwise relatively unbranched polymer. It was found that linear short side branches have about the same effect in decreasing stiffness and increasing toughness as the natural short-chain branches of polyethylene have. However, branches containing a tert-butyl group increased resin toughness more than linear branches while decreasing stiffness by about the same amount. Thus, by adding a small amount of branched, short side branches, it is possible to obtain an optimum balance of physical properties not obtainable from low-density ethylene homopolymer.
    Zusätzliches Material: 3 Ill.
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  • 36
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1479-1492 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A rapid iteration method has been developed to correct the molecular weight averages calculated from raw GPC data for dispersion. Though simple in its performance, it covers the general case that the instrumental spreading characteristics (Tung's resolution factor h) depend on the elution volume. Moreover, it is irrelevant whether the calibration curve, being the logarithmic plot of the molecular weight versus the elution volume, is linear or not. The method has been applied to a number of well-characterized polystyrene mixtures and yields molecular weight averages which agree with those predicted theoretically. The effect of asymmetry exerted by the dispersion on both molecular weight averages M̄n and M̄w is also discussed.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 37
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1641-1648 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: By combining a number of theoretical relationships concerning the effect of molecular weight on melt rheology, an equation may be derived for conversion of melt indexer flow rate to “apparent molecular weight.” In spite of certain evident theoretical shortcomings of this derivation, the method was applied to the determination of the molecular weight of highly crystalline insoluble poly(ethylene sulfide), for which no other method appeared to be satisfactory. When applied to polymer specimens of presumably known molecular weight (e.g., certain ionically initiated specimens), reasonable agreement was found.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 38
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1679-1685 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Using carbon blacks of constant specific surface area and surface chemical characteristics, but differing in degree of structure, it is shown that tensile strength, elongation at break and rupture energy are functions of the product av2, where v2 is the volume concentration of carbon black and a is a structure dependent factor. Moreover, reductions of failure data to a common effective filler concentration are accomplished with the identical structure factors used earlier in modulus reductions. The values of the structure factors are linearly related to the dibutyl phthalate (DBP) absorption of carbon black, when care is taken to equalize the packing density prior to conducting the DBP test.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 39
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The Gram-Charlier series was suggested as an empirical instrument spreading function in the first paper (part I) of this series. In the second paper (part II) of this series, the Fourier transform method was used together with the suggested series to solve Tung's integral equation. In this paper, an alternate method for solving Tung's equation is proposed which eliminates some of the limitations of the Fourier transform method. In the approach used in this study, Tung's integral equation is approximated by a set of linear equations. Since no unique least-squares solution can be computed, a closely related problem whose solution closely approximates the original problem is formulated and solved using singular value decomposition. By avoiding the use of the smallest singular values and forcing the equality of the areas of the corrected and the uncorrected chromatograms, an approximate solution to the original problem is obtained in which the oscillations inherently present due to the ill-posed nature of the problem are filtered out. The performance of the method with the experimental data given in Part II is indicated.
    Zusätzliches Material: 9 Ill.
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  • 40
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1729-1736 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A concentric cylinder conductivity cell with guard heaters was constructed and used to determine the thermal conductivity of polymer melts. Thermal conductivity was found to be a linear function of temperature for the melts studied, and the thermal conductivity decreased as the complexity of the polymer chain increased. The polymers studied were a linear polyethylene, branched polyethylene, polypropylene, polystyrene, nylon 6, and nylon 6,10. The measurements are precise to within ±6%.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 41
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1753-1756 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: In an earlier communication1 the preparation of Bisacid A2 was described. This paper describes the attempts at spotting impurities in the products so obtained by subjecting them to thin-layer chromatography. No traces of impurities could be detected since no separation whatever was observed. Infrared spectra of pure Bisacid A2 were found to be identical with the spectrum of Nanu and Boboescu.2 It was also seen that the product obtained by the standard preparation in 70-73% yield with a minimum melting point of 173°C could not be demonstrably improved by esterification and rehydrolysis. Second crops from first mother liquors from the aqueous acetic acid recrystallization of the crude precipitated product of the condensation reaction (as well as ether extracts from these mother liquors) showed that both contained material with phenolic OH groups. These are the inpurities in the crude product which must be completely removed during purification if the final material is to be used for the synthesis of unsaturated polyester resins for ultimate use as crosslinked reinforced plastics, as alkyd varnish bases, or as fiber-forming saturated polyesters and polyamides. The need for adhering to the standard synthetic procedure was confirmed, in particular the need for multistage condensation, giving an effective yield of 70-73% of pure material
    Zusätzliches Material: 4 Ill.
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  • 42
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1649-1655 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The rheological behavior of the two-phase systems consisting of a polystyrene-in-styrene phase distributed in a rubber-in-styrene phase is shown to exhibit increasing non-Newtonian behavior up to the phase inversion point, as a consequence of its two phase nature. The equation \documentclass{article}\pagestyle{empty}\begin{document}$$ \log \frac{\mu }{{\mu _c }} = 2.5\left( {\frac{{\mu _d + a\mu _c }}{{\mu _d + \mu _c }}} \right)\left( {\phi + \phi ^{{\raise0.7ex\hbox{$5$} \!\mathord{\left/ {\vphantom {5 3}}\right.\kern-\nulldelimiterspace} \!\lower0.7ex\hbox{$3$}}} + \phi ^{{\raise0.7ex\hbox{${11}$} \!\mathord{\left/ {\vphantom {{11} 3}}\right.\kern-\nulldelimiterspace} \!\lower0.7ex\hbox{$3$}}} } \right) $$\end{document} is recommended for the prediction of the viscosity of the polymerizing mass up to phase inversion during the production of HIPS by the in situ bulk polymerization of styrene in the presence of dissolved rubber.
    Zusätzliches Material: 3 Ill.
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  • 43
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1703-1708 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A simple, moderately high shear capillary viscometer which can be used up to a shear rate of 150,0000 sec-1 is described. The use of a twin viscometer arrangement has eliminated the need of elaborate pressure control and adjustment units. Experimental results obtained by use of the viscometer to measure the specific viscosities of a charged colloid at two different shear rates are presented.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 44
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1665-1677 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Membranes of graft copolymers of polyethylene with poly(sodium styrene sulfonate), poly(4-vinylpyridinium methyl bromide), and poly(sodium acrylate) were prepared by using the technique of peroxide grafting. The reverse osmosis characteristics of the membranes were examined as a function of grafting yield. In these membranes, the grafting can be considered as a process of introducing ionic sites, and it depends on the conditions of the grafting reaction, such as monomer concentration and temperature. However, the overall reverse osmosis characteristic is not only dependent on the number of ionic sites introduced but also on the swelling capability of the membrane. Consequently, the salt rejection of grafted membrane of a fixed graft yield depends on the conditions of the grafting reaction. All grafted membranes which have grafting yields above a certain value behave as normal ionic polymer membranes, and their interrelationship of salt rejection and water permeability follow the general dependence found for ionic polymer membranes.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 45
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1709-1715 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Axial stresses generated by polyacrylonitrile filaments heated in air at constant length and length changes of filaments heated at constant load were measured. Fibers subjected to loads less than about 0.1 gpd shrank in the temperature range from about 40°C to 160°C. At about 160°C they began to stretch. Fibers that stretched out again to about their original lengths stiffened temporarily before undergoing a further elongation. At a temperature where the oxidation reaction begins to proceed with appreciable rate, elongation was retarded and finally reversed. Shrinkage was recorded during isothermal heating at 270°C, and a final length was approached when the oxygen content approached about 10 wt-%. The tension generated when the fibers were restrained from shrinking increased as temperature increased to 160°C but dropped in the temperature range of 160° to 250°C. Tension again built up during isothermal oxidation at 270°C. In the case of one of the samples, the tension generated below 160°C exceeded the ultimate tensile strength of the fibers above 200°C. This condition leads to tensile failures when the filaments are heated in a steep thermal gradient. The tensile behavior of the filaments is discussed in terms of the helical molecular model.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 46
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1717-1727 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A comparative thermogravimetric study of ten polyimide films of varying composition revealed that thermal and thermo-oxidative stability of the polymers increases directly with increasing imide content. Films degraded more rapidly in air than in vacuo; the insertion of connecting groups within the polymer repeat unit decreased stability in both environments. The effect of inserting “ladder-like” segments in the polymer structure did not enhance resistance to oxidation; but under vacuum, those segments probably operated beneficially in promoting the retention of the carbon-like residue. Infrared spectral measurements showed little loss of imide bands with progressive weight loss in air, indicating unit-by-unit degradation. Conversely, infrared spectra of films heated under vacuum conditions showed that progressive loss of imide bands occurred simultaneously with an increasing development of bands related to carbon-nitrogen double bonds. Dynamic heating under vacuum developed singularly uniform weight loss curves; however, concurrent mass-spectrographic analyses indicated two distinct reactions. Gaseous carbon monoxide and carbon dioxide species accounted for the major weight change, and their periods of maximum evolution occurred at different temperatures for each film. A subsequent minor weight loss period was associated with the liberation of hydrogen cyanide which maximized at the same temperature for all ten films.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
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  • 47
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The degree of branching of a series of ethylene-vinyl acetate copolymers was found to be strongly dependent upon polymerization temperature. The copolymers were prepared by free-radical polymerization and had low molecular weights and molar ratios of ethylene: vinyl acetate greater than 3:1. Nuclear magnetic resonance and infrared studies showed that copolymers prepared at 150°C were highly branched and had little crystallinity. Branches were mainly alkyl groups on the polymethylene backbone segments. There was no evidence of δ-acetoxyalkyl branches. Long branches originating by intermolecular H abstraction from the acetylmethyl groups were also expected but could not be detected. These results were consistent with an intramolecular “backbiting” mechanism similar to that found in ethylene homopolymerizations. There was little or no participation by the vinyl acetate moiety in the branching scheme. Copolymers prepared at about 90°C had very few long or short branches and were more crystalline. Copolymers prepared between these temperatures had intermediate degrees of branching and crystallinity.
    Zusätzliches Material: 3 Ill.
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  • 48
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1769-1775 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Measurements of solubility parameters of a series of chlorinated poly(vinyl chloride) (CPVC) samples were carried out. A maximum value of solubility parameter occurs at a chlorine content of 63-65% and is related to optimum packing.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 49
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1791-1801 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The grafting reactions of styrene (St), methyl methacrylate (MMA), and vinyl acetate (VAc) were investigated in the presence of n-butyl acrylate-acrylonitrile copolymer. Results showed that the nature of monomer and initiator were the major factors influencing the grafting activity. The grafting efficiency was 0.87 for St, 0.26 for MMA, and 0.18 for VAc under the most favorable conditions. Acrylic rubber reduced the rate of polymerization, and the retarding effect increased in the order St, MMA, VAc. The chain transfer constants for acrylic rubber were evaluated to be 4.8 × 10-4 for St, 1.27 × 10-3 for MMA, and 1.45 × 10-3 for VAc. The rate of polymerization and the grafting efficiency decreased with increasing acrylonitrile content in acrylic rubber, while the chain transfer constant of St for acrylic rubber remained practically unchanged.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 50
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1819-1835 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The change of the mixing state of polybutadiene rubber-polyolefin resin blend resulting from remilling and heat treatment was studied. Polyolfin resins studied here were high-pressure polyethylene, low-pressure polyethylene, and polypropylene. As in case of polybutadiene rubber-general purpose polystyrene resin blend, we made use of the results obtained through hardness and compression modulus measurement and microscopic observation. Even in case of polybutadiene rubber-polyolefin resin blend, the change of mixing state and the softening phenomenon by remilling were observed. The hardening phenomenon by heat treatment of the sample softened by remilling was also observed at high polyolefin resin content. But at low polyolefin resin content, the hardness which had increased once often decreased as the heat treating time increased, and in some cases the nonremilled sample was observed to soften with heat treatment. These phenomena attendant on heat treatment show that the intrinsic nature of a heterogeneous blend system also appears in a microheterogeneous polymer blend system.
    Zusätzliches Material: 22 Ill.
    Materialart: Digitale Medien
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  • 51
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1855-1868 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A comparison is made of the composition and properties of the different rubber vulcanizate networks obtained by varying the ratio of sulfur to sulfenamide accelerator and by the thermal aging of vulcanizates containing predominantly polysulfide crosslinks. It is concluded that the changes in network structure which can take place, for example, during the service life of natural rubber tires are not the direct cause of failures of the type associated with rubber fatigue at high temperatures. However, a reduction in the total number of crosslinks can accelerate failure by increasing the amount of heat generated during flexing. More stable networks giving improved resistance to fatigue at high operating temperatures are obtained by the use of higher ratios of accelerator to sulfur than are conventionally employed.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 52
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1903-1909 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A continuum modification of the bead-spring (elastic dumbbell) theory of dilute solutions of linear macromolecules, recently introduced by Gordon and Schowalter, is used to obtain explicit constitutive equations for the stress and polarizability tensors. The stress constitutive equation, closely related to a semiempirical result obtained earlier by Spriggs, is superior in predictive capability to the constitutive equation obtained from the elastic dumbbell theory. Results are presented for steady shearing flow, large-amplitude oscillatory shearing, and stress relaxation following cessation of steady shearing and are compared with the results of the elastic and rigid dumbbell theories. In general, predictions are similar to those of the rigid dumbbell and thus are in qualitative agreement with experiment.
    Materialart: Digitale Medien
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  • 53
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 1941-1948 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The failure criterion developed by Harwood et al. between energy input to break and hysteresis at break for amorphous rubbers has been related to the fatigue and cut growth properties of the rubber which are based on the tearing energy theory. It is found that the constant K in the hysteresis failure criterion is a function of the cut growth constant G and the inherent flaw size C0. The effect of adding fine particulate fillers to amorphous rubbers on the hysteresis and fatigue properties is considered and shown to be in agreement with the theory.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 54
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 2317-2319 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 55
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 2321-2333 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A computer technique ultimately yielding, from GPC data, both differential and integral molecular weight distributions of macromolecular products with unknown composition and structure has been worked out, based on a “universal” calibration method previously proposed by other authors to calculate average molecular weights. The technique involves as sole assumption the validity of the “universal” calibration for the kind of sample under investigation. The GPC output data are handled through a realtime computer program and punched on paper tape. Together with two experimental parameters of the polymer (average molecular weights, limiting flow number) and the “universal” calibration of the columns set, the tape is used as input for the off-line programming. Examples are presented, showing the accuracy which can be expected.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 56
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 2371-2380 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The intermolecular cyclization reaction is investigated in highly crosslinked epoxy systems, where diepoxides with different mobilities between terminal epoxy groups were crosslinked with ethylene diamine. Based on the measured values of the Clash-Berg 10-sec modulus in the rubbery region, the correlation between the mobility and the cyclization reactivity of the diepoxides is discussed. The epoxide with higher mobility is found to have a higher rubbery modulus than that with lower mobility, as was expected. This is tentatively explained by the difference in the reactivity of the formation of the 11-membered ring. Dynamic mechanical measurements were also run on a forced vibration apparatus. The higher β-transition peak of the polymer of bisphenol-A diglycidyl ether was interpreted in terms of its higher free volume as well as lower density and lower glassy modulus. The higher modulus in the glassy region of ethylene glycol diglycidyl ether-ethylenediamine was explained on the basis of hydrogen bonding.
    Zusätzliches Material: 3 Ill.
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  • 57
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 2417-2424 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The catalyst comprised of triisobutylaluminum, zinc acetylacetonate, and water was used to prepare homopolymer of epichlorohydrin; copolymers of epichlorohydrin with propylene oxide, ethylene oxide, and allyl glycidyl ether; and terpolymers of epichlorohydrin, propylene oxide, and allyl glycidyl ether and of epichlorohydrin, ethylene oxide, and allyl glycidyl ether. The vulcanizates of these rubbers provide variations of stressstrain and dynamic properties, freeze point, hardness, and solvent resistance depending on the type and amount of comonomer. In general, these rubbers have excellent heat, ozone, and oxidation resistance as well as oil and solvent resistance.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 58
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 2453-2460 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: At lower than the glass transition temperature, the cleavage of the molecular chains of extended vulcanized rubbers will occur. The crosslinking density of vulcanized rubbers, which were placed at room temperature for about 4 hr in nitrogen atmosphere, increased about 17% after extension of 200% at -76°C. This may be due to the recombination of cleft chains, and this can be shown by the Maxwellian type of curves between crosslinking density and forced strain. Considering the decreasing proportion of crosslinking density by the radical acceptors included in the rubbers and the fact that crosslinking density increases because of recombination of cleft chains, this was attributed to the recombination of unstable chains produced by the added mechanical stimulus.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 59
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 2103-2114 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Terpolymers of ethylene and propylene with 4-phenyl-, 4-o-tolyl, 4-p-tolyl, and 4-(1-naphthyl)-1-butenes were vulcanized with bisbenzylic halides in the presence of highly acidic clays. The halides include bischloromethyldurene, p-bischloromethylbenzene, and p-bisbromomethylbenzene. Since the polymers contain no olefinic unsaturation, the crosslinking is achieved by electrophilic attack of the halide on the pendant aromatic rings. The order of activity is naphthyl 〉 tolyl 〉 phenyl. The new curing system also reacts with olefinic unsaturation. Thus, an EPDM elastomer and SBR rubber, the latter containing both aromatic rings and double bonds, were also readily crosslinked.
    Zusätzliches Material: 8 Tab.
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  • 60
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 2123-2140 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The ultraviolet stability of polyimides and polyamide-imides was determined in both a wet and dry environment. Films have been exposed to these environments for 3000 and 6000 hr, respectively. The polymers are not stable to UV radiation (2900-4000 Å); serious deterioration of the mechanical properties occurs under both wet and dry conditions with the former giving rise to greater damage. The polyamide-imide polymer is more unstable to UV radiation than the two polyimides evaluated; however, it is more resistant to hydrolysis as indicated from rate data obtained from a kinetic analysis of the mechanical property degradation curves. The electrical properties of the polymers are relatively unaffected in the dry environment but begin to deteriorate as the polymer becomes brittle. In the wet environment these properties begin to deteriorate more rapidly. Dissipation factor and dielectric strength are the properties most affected.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
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  • 61
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 2199-2210 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The pressure-driven transport of liquids employed in reverse osmosis has been shown to occur by a solution-diffusion mechanism in highly swollen polymer membranes. A theory based on this mechanism was successfully used earlier to correlate permeation fluxes for such membranes. Positive confirmation of this theory is provided here by direct measurement of the proposed concentration gradient. A study of the temperature dependence of the liquid diffusion coefficient in the polymer membrane has provided additional evidence of a hydrodynamic regime of diffusion in highly swollen membranes. It is also shown that the proposed ceiling flux in reverse osmosis is equal to the pervaporation flux.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
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  • 62
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 2219-2236 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Diene polymers (i.e., polyisoprene, polybutadiene, and butadiene - styrene copolymers) were hydroxylated in tetrahydrofuran by hydroboration with diborane and subsequent alkaline oxidative hydrolysis. The strong, broad infrared absorption of the product at 3340 cm-1 shows the introduction of hydroxyl group. The properties of hydroxylated diene polymers depend upon the extent of hydroxylation. The less hydroxylated polymers are rubbery. As the extent of hydroxylation increases, the product becomes a white thermoplastic which is soluble in alcohol. The hydroboration of diene polymers with diborane is very rapid. However, if the reaction is continued further, the extent of hydroxylation decreases because of side reactions. The results of acetylation and formylation of the hydroxylated products and the grafting of vinyl monomers onto hydroborated diene polymers are also presented.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 63
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 2567-2577 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Two slit dies have been designed, having aspect ratios of 10 and 20. Three melt pressure transducers were flush-mounted on the long side of the rectangular slot, along the longitudinal centerline of each die. The dies were then used to measure wall normal stresses along the longitudinal direction of polymer melts flowing through the thin slit. The polymeric materials investigated were high-density polyethylene, low-density polyethylene, polypropylene, and polystyrene. The measurement of wall normal stresses were used to determine the rheological properties of melts, namely, the melt viscosity from the slope of axial pressure profiles and the melt elasticity from exit pressures. The present study shows that the rheological properties determined from the slit rheometer are in good agreement with those from the capillary rheometer reported in the author's earlier papers. Therefore it may be concluded that a slit die also may be used as a means of characterizing polymeric materials by their viscous and elastic properties in the molten state.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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  • 64
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 2597-2599 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Zusätzliches Material: 2 Tab.
    Materialart: Digitale Medien
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  • 65
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The hydrochloride salt of 1,1-dimethyl-1-(2-hydroxypropyl)amine methacrylimide (DHA) was synthesized and shown to readily homo- and copolymerize with styrene to produce soluble polymers containing pendent quaternary ammonium groups. These polymers may be treated with base to provide modified polystyrenes containing pendent aminimide residues. The latter polymers may be thermolyzed in solution or in the solid phase to produce modified polystyrenes containing pendent isocyanate groups. If the thermolysis is carried out in the presence of “isocyanate reactive” moieties, high molecular weight, crosslinked polymers may be synthesized. The reactivity ratios of DHA · HCl with styrene were determined: r1 = 0.33 and r2 = 0.35. The Alfrey-Price Q and e values were also calculated: Q = 0.88 and e = 0.67.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 66
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Seven monomers, which varied widely in water solubility and ionic charge, were graft polymerized onto both unswollen starch and starch that had been swollen by heating in water to 60°C. Polymerizations were initiated with ferrous ammonium sulfate hexahydrate-hydrogen peroxide and, where applicable, with ceric ammonium nitrate. Graft copolymers were freed of ungrafted homopolymer by solvent extraction and were characterized by weight percentage of synthetic polymer incorporated in the graft copolymer, molecular weight of grafted branches, and grafting frequency. The influence of starch granule swelling on graft copolymer structure varied with the monomer used and could not be predicted on the basis of water solubility of monomer or its resulting polymer. With acrylonitrile and acrylamide, swollen starch gave higher molecular weight and less frequent grafts than unswollen starch. However, methyl methacrylate, N,N-dimethylaminoethyl methacrylate · HNO3, N-t-butylaminoethyl methacrylate. HNO3, and 2-hydroxy-3-methacryloyloxypropyltrimethylammonium chloride produced less frequent graft of higher molecular weight when starch was unswollen. With acrylic acid, graft molecular weight was independent of starch granule swelling, although grafting was less frequent when swollen starch was used.
    Zusätzliches Material: 6 Tab.
    Materialart: Digitale Medien
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  • 67
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 2687-2697 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Investigations of glass transition phenomena were carried out on vinylidene chloride - acrylonitrile copolymers, purified commercial samples of known composition. With a view to analyzing this effect, the following physical parameters were investigated: specific volume Vs,25, Tg, and volume expansion coefficients αL, αg, and Δα. The experimental results were analyzed on the basis of semiempirical and theoretical equations describing transitions to the glassy state. It was found that Tg dependence on weight fraction C2 of acrylonitrile may be described by Wood's equation, with k = 5.88. Applying Gibb's and Kanig's theories as well as relations given by Hirai and Small, the energies associated with intermolecular interactions (A*AB, E0, Eh, CED), and intramolecular interactions (stiffness energy ε) were calculated for copolymers of different composition. The copolymer Tg was found, above all, to depend on the stiffness energy ε, which increases with increasing acrylonitrile content in the copolymer.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
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  • 68
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 2277-2292 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The polymerization (polymer deposition) rate of styrene in an electrodeless glow discharge from styrene vapor and a mixture of styrene vapor and gas (H2, He, A, and N2) was investigated. The rate of polymerization, R, was found to be independent of the discharge power. The rate of polymerization of the pure monomer was found to be proportional to the square of monomer pressure pM. The addition of gas increased the rate of polymerization depending upon the partial pressure of the gas, px, and R can be generally expressed by R = a[pM]2{1 + b[px]}. The value of b is dependent of the type of gas and follows the order of N2, 〉 A 〉 He 〉 H2. The distribution of polymer deposition was found to be nearly independent of the partial pressure of the gas and of the discharge power with N2 and H2 as plasma gas; however, with He and A, the distribution is highly dependent on the partial pressure of the gas and on the discharge power. The study strongly suggests that polymerization occurs in the vapor phase and that the growing polymer radicals deposit on the surface of the discharge vessel, yielding highly crosslinked polymer deposition.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
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  • 69
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 2303-2315 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The mechanical behavior of three kinds of organic foams, each at two different densities, was experimentally investigated under conditions of pulsed one-dimensional strain shock loading. The input pulse width in each experiment was nominally 0.1 μsec, and the input stress level (as referenced to quartz) was varied between 10 and 23 kbar. The materials studied were polyurethane foam at bulk densities of 0.33 and 0.21 g/cc, syntactic foam (phenolic microballoons dispersed in a resin binder) at 0.66 and 0.23 g/cc, and polystyrene bead foam at 0.091 and 0.049 g/cc. Specimen thicknesses varied between 1.0 and 6.5 mm. It was found that the pulse duration was greatly lengthened and that the peak stress was decreased (accounting for both impedance mismatch and attenuation effects) by factors of between about 8 and 500, depending upon the type of foam, its thickness, and its density.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 70
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 2357-2369 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Using the Weissenberg rheogoniometer, a technique has been developed which facilitates the measurement of shear stress data and which substantially overcomes the problem of sample loss that normally occurs at high shear rates. Using this technique, the apparent viscosities of PVC pastes based upon four different PVC paste polymers plasticized with dialphyl phthalate have been determined at a number of shear rates up to 9000 sec-1 and the viscosity aging characteristics of these paste polymers have been compared. The effect of several common plasticizers upon PVC paste viscosity and viscosity aging have been studied at shear rates of the order of 10 sec-1 and 1000 sec-1.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 71
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 2645-2650 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: A new synthesis for carboranesiloxane polymers has been discovered. It involves the alcoholysis of the bischlorodimethylsilylcarborane monomers and the generation of the HCl catalyst in situ. Alcoholysis is applicable to the synthesis of most carborane-siloxane polymers, with the probable exception of the SiB-1 homopolymers of the larger carboranes. The attack of the B—H moieties in the carborane cage can be minimized both by the utilization of a tertiary alcohol and by the addition of excess acid when a primary alcohol is employed.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 72
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 2439-2445 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Criteria for establishing a universal GPC calibration for poly-1,2-butadiene on the basis of polystyrene standards are considered. The number-average molecular weights of the two polymers are related by a linear expression on the assumption that their respective Mark-Houwink exponents are equal. The coefficient Cn of this expression, determined from GPC and viscosity measurements, remained constant for a considerable range of molecular weights and polydispersities. The applicability of Cn beyond the interval of present measurements is considered on the basis of results in the literature. The results are comparable to those obtained from a universal calibration based on the unperturbed dimension of polymer chains, but do not agree with those obtained from a model based on extended length.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 73
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: The temperature dependence of the shear modulus G′ and of the damping tan δ of poly-(vinyl chloride), poly(vinylidene chloride), copolymers of vinyl chloride-vinylidene chloride, PVC chlorinated in solution and suspension, and chlorinated polyethylene was measured. Secondary relaxation process of PVC and its derivatives are being explained as vibration of methylene groups polarized by neighboring CCl dipoles. This process, being suppressed by lowering the concentration of the methylene groups in the PVC chain (e.g., by chlorination), remains, however, unaffected by the growth of crystalline content. The achieved results show that in the α-transition region there occurs, in accordance with Andrews' theory, a loosening of the bonds between the CCl dipoles, whereas in the β-transition region a loosening of the weaker bonds among the dipoles of the polarized methylene.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
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  • 74
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 15 (1971), S. 3109-3116 
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: Nylon fibers tested in tension at -196°C show ductile strains up to 75%. The ductility is a complicated function of draw ratio, because decreasing work hardening with decreasing draw ratio leads to a point of instability where necking begins. The necks presumably initiate fracture, have the appearnce of cracks, and have been previously seen on fibers drawn in various organic liquids. Recovery experiments showed that molecular motions involved in low temperature deformation differ from those involved in ambient temperature deformation.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 75
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Die Beziehung zwischen der Struktur der Übergangsmetall-Allyl-Verbindungen und ihrer Fähigkeit, Äthylen zu polymerisieren, wurde untersucht. Von Ti, Zr, Hf, Cr und V abgeleitete isoleptische Allylverbindungen sind sämtlich aktive Polymerisationskatalysatoren. Die Abwandlung der Allylgruppe durch Substitution mit Methyl erhöht die Aktivität, während ein Phenylsubstituent sie vermindert. Der Austausch von Allylgruppen durch Halogenatome erhöht die Aktivität merklich; der aktivste Katalysator war hier Zr(allyl)Br3. Liganden wie Cyclopentadienyl, CO, OH etc. machen diese Verbindungen als Initiatoren unwirksam. Wichtige Schlußfolgerungen im Bezug auf die strukturellen Bedingungen für eine koordinative anionische Polymerisation dieser Art werden gezogen. Kinetik und Mechanismus der Polymerisation werden diskutiert.
    Notizen: The relationship between the structure of transition metal allyl compounds and their ability to polymerise ethylene has been studied. Isoleptic allyl compounds derived from Ti, Zr, Hf, Cr, Nb, and V are all active as polymerisation catalysts. Substituents in the allyl group such as methyl increase the activity whereas substituents such as phenyl decrease it. Replacement of some of the allyl groups by halogen atoms increase activity markedly, the most active catalyst being Zr(allyl)Br3. Ligands such as cyclopentadienyl, CO, OH, etc., render these compounds inactive in polymerisation.Important conclusions are drawn concerning the structural requirements for coordinated anionic polymerisation of this kind, and kinetics and mechanisms of polymerisation are discussed.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 76
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 144 (1971), S. 183-192 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: The polymerization of 2.5-dioxopiperazine (DOP) can be initiated with SnCl4/C2H5MgBr, C2H5SnCl3, (C2H5)2SnCl2 or (C2H5)3SnCl in dimethylsulfoxide at temperatures between 40 and 120°C. Infraredspectroscopic measurements of the reaction products between DOP and ethyltin-chlorides point to the primary formation of tin-nitrogen bonds. The hydrogenchloride deliberated in this reaction is the true initiator for the polymerization. The polymerization in bulk is also possible with the salt of hexamethylenediamine and adipic acid (200°C) or 2.5-dioxopiperazine dihydrochloride (160°C) as initiators. In no case monomer conversions greater than 8% have been found.
    Notizen: 2.5-Dioxopiperazin (DOP) läßt sich mit SnCl4/C2H5MgBr, C2H5SnCl3, (C2H5)2SnCl2, (C2H5)3SnCl in Dimethylsulfoxid bei Temperaturen zwischen 40 und 120°C sowie in Substanz mit dem Salz aus Hexamethylendiamin und Adipinsäure (200°C) oder 2.5-Dioxopiperazin-dihydrochlorid (160°C) als Initiatoren zu Umsätzen von maximal 8% polymerisieren. Infrarotspektroskopische Untersuchungen an den Reaktionsprodukten aus DOP und Äthylzinnchloriden sprechen für die primäre Ausbildung von Zinn-Stickstoff-Bindungen. Der abgespaltene Chlorwasserstoff ist der eigentliche Initiator der Polymerisation.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 77
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 144 (1971), S. 169-182 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: 1.3-Dioxolan (DiOX) reagiert mit SbCl5 unter Bildung von 1.3-Pioxoleniumhexachlor-antimoniat (Dn), HCl und SbCl3. Dn zersetzt sich in Losung zu β-Chlorathylformiat unter Rückbildung von SbCl5: Wenn DiOX mit (C6H5)3C⊕ SbCl6⊖ reagiert, bilden sich nach der MEERWEINschen Reaktion Dn und (C6H5)3CH trotz des Gleichgewichts zwischen SbCl5 mit dem Triphenylmethylsalz. Obwohl weder HCl allein noch HCl + SbCl3 (HSbCl4) die Polymerisation von DiOX initiieren, reagiert HC1 rasch mit DiOX und gibt erwartungsgemäß,Äthylenglykolmonomethyl-äther. Die Polymerisation kann also initiiert werden, wenn dieser Äther weiter mit SbCl5reagiert oder wenn sich H⊕ SbCl6 (HCI + SbCl5) direkt mit DiOX umsetzt. Als eine Alter- native sollte PLESCHS Ringerweiterungsmechanismiis mit einem protonierten Monomeren in Betracht gezogen werden.Läßt man eine Modellverbindung, das Äthoxycarboxoniumhexachlorantirnoniat (CH3CH2OCH2⊕ SbCl6⊖), mit DiOX reagieren, verschwindet ein Teil der SbCl6⊖-Anionen, und es bildet sich SbCl3, wodurch die Reaktion zwischen SbCl5 und DiOX auch in diesem Fall bewiesen wird. Wird jedoch das Äthoxycarboxoniumhexach1orantimoniat vorher durch Zusatz eines linearen Acetals (z.B. CH30CH20CH3) „stabilisiert“, wobei sich das entsprechende tertiare Oxomiumion bildet: dann wird seine Reaktion mit DiOX von keiner Wasserstoffübertragungsreaktion begleitet, und das SbCl6⊖ bleibt vollstandig unangegriffen.Eine ins Einzelne gehende UV-Untersuchung des Reaktionsgemisches und aller Komponenten, die darin enthalten sind, machte es uns möglich, λmax und εmax des größten Teils der Zwischenprodukte zu bestimmen, die sich im Verlaufe der Initiierung bilden, d.h. in dem Zeitabschnitt, in dem der Vorlaufer des Initiators (C6H5)3C⊕ SbCl6⊖ oder SbCl5) sich in den eigentlichen Initiator umwandelt.
    Notizen: 1.3-Dioxolan (DiOX) reacts with SbCl5 giving 1.3-dioxolenium hexachloroantimonate (Dn), HCl and SbCl3. Dn decomposes in solution, forming β-chloroethylformate and reproducing SbCl5. When DiOX is reacted with Ph3C⊕ SbCl6⊖ Dn and PhCH are formed according to MEERWEIN's reaction in spite of SbCl5 being in equilibrium with the trityl salt. Although neither HCl alone ner HCl + SbCl3 (HSbCl4) initiate the polymerization of DiOX, HCl readily reacts with DiOX, giving ethylene glycol monochloromethylether according to expectations. The polymerization can thus be initiated when this ether reacts further with SbCl5 or when H⊕ SbCl6⊖ (HCl + SbCl5) reacts directly with DiOX. As an alternative PLESCH's ring expansion mechanism, involving a protonated monomer, should be considered.When a model compound, ethoxycarboxonium hexachloroantimonate (CH3CH2OCH2⊕ SbCl6⊖), is reacted with DiOX some of the SbCl6⊖ disappears and instead SbCl3 is formed, indicating the interaction between SbCl5 and DiOX also in this case. If however, prior to this reaction, the ethoxycarboxonium hexachloroantimonate, is “stabilized” by addition of a linear acetal (e.g. CH3OCH2OCH3) and formation of the corresponding tertiary oxonium ion: then its reaction with DiOX is not accompanied by any hydride transfer reaction and [SbCl6⊖] is fully preserved.A detailed UV study of the reaction mixture and all the components involved enabled us to determine λmax and εmax for the majority of intermediate compounds formed in the course of initiation, i.e., when the initiator precursor (Ph3C⊕ SbCl6⊖ or SbCl5) is transformed into the true initiator.
    Zusätzliches Material: 3 Ill.
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  • 78
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Die Kinetik der mit Fluorenyltetrabutylammonium initiierten Polymerisation von Propylensulfid in Tetrahydrofuran wurde bei -30°C untersucht. In diesem Lösungsmittel ergeben sich für die Wachstumskonstanten der freien Ionen und Ionenpaare 6 bzw. 2,5 l/Mol sec. Der letzte Wert ist etwa 1000 mal größer als der entsprechende Wert bei -30°C, wenn Natrium als Gegenion vorliegt. Die sehr großen Geschwindigkeitskonstanten der mit quartären Ammoniumsalzen initiierten Polymerisation ergeben sich aus der großen Wachstumskonstante der Ionenpaare und aus ihrer starken Dissoziation.
    Notizen: La cinétique de polymérisation du sulfure de propylène amorcée par le fluorényltétrabutylammonium a été étudiée en solution dans le tétrahydrofuranne à -30°C. Dans ce solvant, les constantes de vitesse de propagation sur les ions libres et sur les paires d'ions sont respectivement égales à 6 et à 2,5 l · mole-1 · sec-1. Cette dernière valeur est environ mille fois plus grande que la valeur correspondante sur les paires d'ions thiolate de sodium à -30°C.La très grande valeur de la constante de propagation sur les paires d'ions ainsi que la valeur assez élevée de la constante de dissociation sont les facteurs qui déterminent les vitesses très grandes des polymérisations amorcées par les sels d'ammonium quaternaire.
    Zusätzliches Material: 6 Ill.
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  • 79
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 149 (1971), S. 135-152 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Die Reaktionen zwischen Methyl-α-chloracrylat (MCA) und zinkorganischen Verbindungen wurden untersucht. Es konnte gezeigt werden, daß es sich bei den ersten Reaktionsschritten zwischen MCA und Zink-di-n-butyl (n-Bu2Zn) in Toluol und Tetrahydrofuran (THF) um Additionsreaktionen an eine konjugierte Doppelbindung und une Carbonyladditionsreaktionen handelt. Zink-n-butyldimethylmalonat (n-BnZnDMM) unterliegt andererseits lediglich einer Addition an konjugierte Doppelbindungen. Einige Teile der konjugierten Additionsverbindungen lagerten sich zu Derivaten des Cyclopropans um.Es konnte gezeigt werden, daß α-Chlormethylacrylat in Toluol und THF mit n-Bu2Zn und n-BuZnDMM als Initiator polymerisiert. Sowohl die Ergebnisse einiger Copolymerisationsreaktionen als auch kinetische Untersuchungen weisen darauf hin, daß der Mechanismus der Polymerisation in Toluol oder THF radikalischer Natur ist. In Hexamethylphosphorsäuretriamid (HMPT) jedoch polymerisiert dieses Monomere über einen anionischen Mechanismus. überhaupt kein Anzeichen bezüglich der Bildung von Cyclopropan konnte, sofern HMPT als Lösungsmittel verwendet wurde, gefunden werden, nicht einmal dann, wenn die Reaktion mit einem überschuß an zinkorganischen Verbindungen durchgeführt wurde.
    Notizen: The reactions of methyl α-chloroacrylate (MCA) with organozinc compounds were studied. The elementary reactions of MCA with di-n-butylzinc (n-Bu2Zn) in toluene and tetrahydrofuran (THF) were found to be conjugate addition and carbonyl addition reactions. n-Butyl(dimethyl malonato)zinc (n-BuZnDMM), on the other hand, underwent only conjugate addition reaction. Some parts of the conjugate addition products were transformed to cyclopropane derivatives.Methyl α-chloroacrylate was found to be polymerized in toluene and THF with n-Bu2Zn and n-BuZnDMM as initiator. Results of some copolymerization reactions as well as kinetic studies indicated the mechanism of the polymerization in toluene or THF to be radical type. In hexamethylphosphoric triamide (HMPT), however, this monomer was polymerized through anionic mechanism. Any sign of the cyclopropane formation was not detected in HMPT as solvent even in the reaction with an excess of the organozinc compounds.
    Zusätzliches Material: 15 Ill.
    Materialart: Digitale Medien
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  • 80
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 149 (1971), S. 169-175 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Die relativen Geschwindigkeiten von Spaltung und Vernetzung beim thermischen Abbau von Polymethylacrylat bei 210 und 243°C wurden nach der Methode von CHARLESBY und PINNER bestimmt. Die relative Häufigkeit der Vernetzung gegenüber der Spaltung nimmt zu, wenn der Anteil an Verzweigungen in den eingestzten Proben ansteigt.
    Notizen: By using the treatment of CHARLESBY and PINNER the relative rates of scission and crosslinking during the thermal degradation of poly(methyl acrylate) at 210 and 243°C have been determined. It is shown that the relative frequency of crosslinking to scission increases as the degree of branching in the sample increases.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
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  • 81
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 149 (1971), S. 177-183 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Die Mikrotaktizität von radikalisch polymerisierten Polymethacrylaten, die in der Seitenkette des Monomeren immer größere Gruppen haben, wird durch die dochaufgelösten Kernresonanzspektren der entsprechenden Polymethylmethacrylate bestimmt.Die Syndiotaktizität vermindert sich schrittweise von Polymethylmethacrylat bis zu Polytriäthylmethylmethacrylat in der Reihe der gesättigten Polymeren. Die aromatischen Polymethacrylate haben eine geringere Syndiotaktizität als die entsprechenden gesättigten Polymeren. Polytritylmethacrylat stellt den Extremfall dar.Die Mikrotaktizität der Polymeren folgt sowohl aus der Größe und der Polarisierbarkeit der Estergruppe als auch aus der Wirkung, die die aromatischen Ringe aufeinander ausüben.
    Notizen: The microtacticity of polymethacrylates prepared by radical initiated polymerization of monomers with side groups of increasing bulkiness is determined by high resolution nuclear magnetic resonance of the corresponding poly(methyl methacrylates).The syndiotacticity decreases systematically from poly(methyl methacrylate) to poly(triethylmethyl methacrylate) in the series of the saturated polymers.The aromatic polymethacrylates have a lower syndiotacticity than the corresponding saturated polymers and poly(trityl methacrylate) is the extreme case.The microtacticity of the polymers is undoubtedly determined by the bulkiness and the polarisability of the ester group as well as by specific interaction between the aromatic rings.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 82
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Es wurden Polymerisation in Gegenwart von Alkoholen und Benzol als Polymerlösungsmittel (mixed-solvent system) untersucht. Die Kettenübertragungsfähigkeit aliphatischer Alkohole nimmt mit der Größe der Alkylkette in folgender Ordnung zu: Methylalkohol 〈 Äthylalkohol 〈 n-Propylalkohol 〈 Isopropanol. Nach den Ergebnissen ist eine Ablösung von α-Wasserstoff aus dem Substrat übertragend wirksam. Die durch die übliche Auftragung von 1/P̄ gegen [S]/[M] erhaltenen Kettenübertragungskonstanten stimmen gut mit Werten überein, die aus den mittels der Farbverteilungstechnik gemesse nen Hydroxylendgruppengehalten berechnet wurden. Die steigenden Werte der übertragungskonstante mit wachsender Zahl der Kohlenstoffatome im Alkohol wird durch die Wahrscheinlichkeit zugänglicher Wasserstoffatome in der Alkylgruppe erklärt. Die Kettenübertragungswerte werden durch die Fällung der Polymeren beeinflußt. Es wurden aus den Kettenübertragungswerten der Alkohole für verschiedene Temperaturen thermodynamische Parameter berechnet.
    Notizen: Studies on Polymerization in the presence of alcohols has been carried out using mixed solvent system. It is observed that chain transferring capacity of the aliphatic alcohols do increase with the size of the alkyl group, the order being methyl alcohol 〈 ethyl alcohol 〈 n-propyl alcohol 〈 iso-propyl alcohol. The results indicate that α-hydrogen abstraction from the substrate is effective. The chain transfer constants obtained from the conventional plot of 1/P̄ against S/M is in fair agreement with the values computed from the estimation of hydroxyl end group in the polymer by dye-partition technique. The increasing transfer constant values in the alochol series with increase in the number of carbon atoms is explained on the basis of probability of available hydrogen atom in the alkyl group. It is also observed that the chain transfer values are affected due to precipitation of polymer. Thermodynamic parameters have been computed from the chain transfer values of alcohols at different temperatures.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 83
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 149 (1971), S. 185-195 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Acht Fraktionen von Poly-4-chlorophenylmethacrylat, dargestellt durch radikalische Polymerisation, wurden durch Viskositätsmessungen in verschiedenen Lösungsmitteln, durch Sedimentation, osmotischen Druck und Lichtstreuung in Benzol untersucht. Die mittlere ungestörte Dimension wurde auf verschiedene Weise mit guter übereinstimmung erhalten, obgleich der Molekulargewichtsbereich groß war. Die Ergebnisse wurden mit den für andere ähnliche Polymethacrylsäureester gefundenen Werten verglichen und zeigen, daß para-Substitution in der Phenylgruppe wenig Einfluß auf die Kettenbeweglichkeit hat.
    Notizen: Eight fractions of poly-4-chlorophenylmethacrylate prepared by radical polymerization have been studied by viscosity in various solvents, by sedimentation, osmotic pressure and light-scattering in benzene.The average unperturbed dimension was obtained in different ways with a good agreement, although the molecular weight range is large. The results as compared with those given for other polymethacrylic esters of the same type show that the effect of a para-substitution in the phenyl group has little effect on the flexibility of the chain.
    Zusätzliches Material: 6 Ill.
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  • 84
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 149 (1971), S. 221-229 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Die durch Azibenzil (AB) initiierte Polymerisation von Methylmethacrylat wurde kinetisch untersucht. Die Polymerisationsgeschwindigkeit (Rp) folgt der Gleichung Rp = k[AB]0.47[MMA]0.97. Die Polymerisation verläuft nach einem radikalischen Mechanismus. Die Bruttoaktivierungsenergie für die Polymerisation wurde zu 16.1 kcal/Mol bestimmt. Die Zersetzungsgeschwindigkeit von AB wurde in Benzol gemessen; es gilt die Gleichung: kd[sec-1] = 5.75·1010 exp(-21.9 kcal/RT). Auf Grund dieser Ergebnisse wird der Startmechanismus diskutiert.
    Notizen: The polymerization of methyl methacrylate initiated by azibenzil (AB) was studied kinetically. The initial rate of polymerization (Rp) was found to be expressed by the equation Rp = k[AB]0.47[MMA]0.97. The polymerization proceeded through a radical mechanism. The overall activation energy for the polymerization was estimated as 16.1 kcal/mole. Furthermore, the rate of decomposition of AB was measured in benzene and the following rate equation was obtained: kd[sec-1] = 5.75·1010 exp(-21.9 kcal/RT). From these results the initiation mechanism was discussed.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 85
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 149 (1971), S. 243-251 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Kettenübertragungskonstanten von aromatischen Aminen bei der Polymerisation von Methacrylsäuremethylester mit Benzol als Verdünnungsmittel (mixed-solvent method) wurden bestimmt. Die Übertragungskonstanten nehmen in folgender Reihe ab: Anilin 〈 N-Methylanilin 〈 N-Dimethylanilin. Die Kettenübertragungsfähigkeit der Amine wird auf Grund einer polaren Struktur im Übergangszustand erklärt. Eine Substitution, welche die Elektronenabgabe des Amino-Stickstoffs fördert, gibt eine größere Übertragungsfähigkeit. Die durch die Amine bedingte Abnahme der Polymerisationsgeschwindigkeit ist von der gleichen Ordnung wie jene der Kettenübertragungsfähigkeit und wird auf Grund einer Hyperkonjugation erklärt. Die Bestimmung der Aminoendgruppen im Polymeren mittels der Farbverteilungstechnik stützt den für die Übertragungsreaktion der Amine angenommenen Mechanismus.
    Notizen: Chain transfer constants of amines have been determined in the polymerization of methyl methacrylate using the mixed-solvent method. The transfer constants are in the order of aniline 〈 methyl aniline 〈 dimethyl aniline. The chain transferring ability of amines has been explained in the light of the polar structure of the transition state. Substitution enhancing electron donating capacity of the amine nitrogen results in higher transferring ability. The decrease in the rate of polymerization due to amines, is in the same order as that of chain transferring capacity and is explained on the basis of hyperconjugation. The estimation of amino end group in the polymer by dye-partition technique supports the mechanism suggested for transfer reaction of amines.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 86
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: The radiation induced solid-state polymerization of tetroxane and trioxane was investigated. The influence of radiation-dose, reaction-time and temperature on yield and molecular weight was studied. Post-polymerization of both monomers shows a limiting conversion which increases with increasing reaction temperature. The activation energy of the post-polymerization was determined to 24 ± 2 (kcal/mole) in the case of tetroxane and was 36-38 (kcal/mole) in the case of trioxane. Time(t)-conversions(x)-curves for tetroxane could be described by the empirical equation: \documentclass{article}\pagestyle{empty}\begin{document}$$x = k_1 t/(1 + k_2 t)$$\end{document} whereby k1 and k2 are constants which could be evaluated by an appropriate plotting of the experimentally obtained data. Contrary to the post-polymerization of trioxane a pro-portionality between molecular weight, conversion and polymerization temperature was found in the case of tetroxane such that with increasing conversion higher molecular weights were obtained and an increase of reaction-temperature gave rise to higher molecular weights at constant conversion. The highest molecular weight obtained by post-polymerization of tetroxane was of the order of 8·105 and ca. 4·105 in the case of trioxane. The probability of chain-transfer is considerably higher with the polymerization of trioxane as compared with tetroxane.The morphology and texture of the originating polymers can be connected - at least qualitatively - with the reaction kinetics. It is highly probable that the kinetics of the polymerization of tetroxane are governed to some extent by relaxation processes of the growing polymer chains.
    Notizen: Die strahlungsinduzierte Polymerisation von kristallinem Tetroxan und Trioxan wurde untersucht und der Einfluß von Strahlendosis, Reaktionszeit und -temperatur auf den Umsatz und das Molekulargewicht der entstehenden POM, insbesondere bei der Nachpolymerisation, studiert. Die Zeit-Umsatz-Kurven für die Nachpolymerisation laufen bei beiden Monomeren asymptotisch gegen einem Grenzwert des Umsatzes, der mit steigender Reaktionstemperatur ansteigt. Die Aktivierungsenergie der Nachpolymerisation wurde zu 24 ± 2 kcal/Mol für Tetroxan und zu 36-38 kcal/Mol für Trioxan bestimmt. Die Zeit(t)-Umsatz(x)-Kurven für Tetroxan lassen sich durch die empirische Gleichung: \documentclass{article}\pagestyle{empty}\begin{document}$$x = k_1 \cdot t/(1 + k_2 t)$$\end{document} beschreiben, wobei k1 und k2 Konstanten sind, die durch geeignete Auftragung der Meßwerte ermittelt werden können. Im Gegensatz zu Trioxan findet man bei Tetroxan eine Proportionalität zwischen Molekulargewicht, Umsatz und Polymerisationstemperatur in der Weise, daß mit steigendem Umsatz höhere Molekulargewichte beobachtet werden und bei konstantem Umsatz mit steigender Temperatur auch höhere Molekulargewichte auftreten. Bei der Nachpolymerisation von Tetroxan lagen die höchsten erreichbaren Molekulargewichte bei 8·105, während bei Trioxan nur Werte von 4·105 erreicht wurden. Die Wahrscheinlichkeit für übertragungsschritte ist bei der Polymerisation von Trioxan wesentlich höher als bei Tetroxan.Zwischen der morphologischen Beschaffenheit und Textur der entstehenden Polymeren und den kinetischen Befunden lassen sich qualitative Beziehungen herstellen. Danach wird die Reaktionskinetik im Fall der Polymerisation von Tetroxan wesentlich durch Relaxationsvorgänge an den sich bildenden Polymerketten beeinflußt.
    Zusätzliches Material: 13 Ill.
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  • 87
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 149 (1971), S. 253-260 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: The chromatogrphic separation of nucleosides, mononucleotides, and dinucleosidephosphates on column of polymer gels containing covalently attached nucleoside residues was studied.In the presence of water nucleosides interact more strongly with the polymer gels thus allowing quantitative separation of nucleosides from mononucleotides and dinucleosidephosphates. In the presence of aqueous buffer solutions, however, nucleosides and dinucleosidephosphates are eluted together thus allowing the separation of mononucleotides from nucleosides and dinucleosidephosphates.
    Notizen: Die säulenchromatographische Trennung von Nukleosiden, Mononukleotiden und Dinukleosidphosphaten an Polymergelen mit kovalent eingebauten Nukleosidresten wurde untersucht.In Wasser treten Nukleoside so stark mit den Nukleosidgelen in Wechselwirkung, daß eine quantitative Trennung der Nukleoside von Mononukleotiden und Dinukleosidphosphaten möglich ist. Dagegen werden in einer wäßrigen Pufferlösung Nukleoside und Dinukleosidphosphate gemeinsam eluiert, so daß eine Trennung der Mononukleotide von Nukleosiden und Dinukleosidphosphaten gelingt.
    Zusätzliches Material: 11 Ill.
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  • 88
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: In the literature, different heterogeneity corrections are used to determine the undisturbed dimensions by the various methods.These corrections as well as the correlations between Mw, MsD, and M[η] are recalculated on the basis of the SCHULZ-ZIMM distribution function.The new values are in some cases remarkably different from those used so far. Thus a reinterpretation of certain corresponding literature data should be considered.
    Notizen: Die bei den verschiedenen Verfahren zur Bestimmung der ungestörten Dimensionen in der Literatur verwendeten Uneinheitlichkeitskorrekturen sowie die Beziehung zwischen Mw, MsD und M[η] werden unter Zugrundelegung der Verteilungsfunktion nach SCHULZ-ZIMM neu berechnet.Die neuen Werte unterscheiden sich von den bisher gebräuchlichen z.T. erheblich, was eine Neuinterpretation der davon betroffenen Literaturdaten nahelegt.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 89
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 149 (1971), S. 261-269 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: By assistance of nucleoside gels, it was possible to separate in aqueous environment not only mixtures of mono-, di- and trinucleotides but also mixtures of these three species one with another. The results of separation show, that the strength of retardation for the nucleotides on nucleoside-gels increased if the purine share increased. Therefore the formation of base pairs between the nucleoside residues which are bound at the gel and the nucleotides followed predominantly the rule of base stacking. From this reason can be formed also base pairs not in the sence of WATSON and CRICK.
    Notizen: Mit Hilfe von Nukleosidgelen war es in wäßrigem Milieu möglich, nicht nur Gemische von Mono-, Di- und Trinukleotiden, sondern auch Gemische dieser drei Spezies untereinander zu trennen. Die Trennergebnisse zeigen, daß die Stärke der Retardierung von Nukleotiden an Nukleosidgelen mit steigendem Purinanteil ansteigt. Daher erfolgt die Basenpaarung zwischen den am Gel gebundenen Nukleosidresten und den gelösten Nukleotiden vorwiegend über den Stapeleffekt. Aus diesem Grund können auch Basenpaare entgegen dem Sinne von WATSON und CRICK gebildet werden.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
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  • 90
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 149 (1971), S. 291-294 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 91
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 149 (1971), S. 295-301 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 92
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 149 (1971), S. 303-308 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
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  • 93
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 149 (1971), S. 309-312 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
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  • 94
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 150 (1971), S. 41-50 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: SO3 is a vigorous initiator of the cationic polymerization of ethylene sulfide in anhydrous medium. Kinetic data, chemical analysis of the end groups and IR-spectroscopic investigation of the polymer are in accordance with a direct, zwitterionic initiation step yielding and disprove the cocatalysis mechanism. The episulfonium ions are quickly deactivated by forming unreactive acyclic sulfonium ions with the sulfide groups of the oligomers. This explains the low kinetic chain lengths and the insolubility due to branching or crosslinking of the reaction product.
    Notizen: SO3 verursacht eine heftige Polymerisation von Äthylensulfid in wasserfreien, inerten organischen Lösungsmitteln. Die kinetischen Daten, die chemische Analyse der Endgruppen und die IR-spektroskopische Untersuchung des Polymerisats sprechen gegen eine Cokatalyse und für einen direkten zwitterionischen Initiierungsschritt unter Bildung von Die kationischen aktiven Zentren werden rasch durch Reaktion mit den Sulfidgruppen des Oligomeren unter Bildung nicht wachstumsfähiger, acyclischer Sulfoniumionen desaktiviert; dadurch bleiben die kinetischen Kettenlängen klein, und es entsteht ein verzweigtes oder vernetztes, unlösliches Produkt.
    Zusätzliches Material: 1 Ill.
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  • 95
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Homopolymers of 3(resp. 5)-vinyl-pyrazolderivates were obtained by radical solution polymerisation and their properties were examined. Resins of limited swelling were prepared by copolymerisation of 2.5 mole-% bis-[3(resp. 5)-vinyl-5(resp. 3)-pyrazolyl]-ketone with 3(resp. 5)-vinyl-5(resp. 3)-pyrazolecarboxylic acid ethyl ester (I) or 3(resp. 5)-vinyl-4.5(resp. 3)-pyrazoledicarboxylic acid dimethyl ester (II). By saponification they were converted to poly-vinyl-pyrazole-carboxylic acid resins (resin A1 and resin A2). The latter are chelating resins of high capacity. The possibility of binding the metal ions Cu2⊕, Ni2⊕, Zn2⊕, and Mg2⊕ and the sorption rate was studied in the pH range 1-5.5.
    Notizen: Durch radikalische Lösungspolymerisation wurden Homopolymere von 3(bzw. 5)-Vinylpyrazol-derivaten erhalten und deren Eigenschaften untersucht. Durch Copolymerisation von 2,5 Mol-% Bis-[3(bzw. 5)-vinyl-5(bzw. 3)-pyrazolyl]-keton mit 3(bzw. 5)-Vinyl-5(bzw. 3)-pyrazol-carbonsäureäthylester (I) bzw. 3(bzw. 5)-Vinyl-4.5(bzw.3)-pyrazol-dicarbonsäuredimethylester (II) wurden Harze dargestellt, die nur begrenzt quellbar sind und die durch Verseifung in Poly-[vinyl-pyrazol-carbonsäure]-harze (Harz A1 und Harz A2) überführt wurden. Diese Harze stellen hochkapazitive Chelatharze dar. Es wurde das Metallionenbindungsvermögen für Cu2⊕, Ni2⊕, Zn2⊕ und Mg2⊕ und die Aufnahmegeschwindigkeit in Abhängigkeit vom pH-Wert im Bereich von pH 1 bis pH 5,5 untersucht.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 96
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: The cationically initiated reaction of tetrahydrofuran (THF) with dicarboxylic acid anhydrides yields poly ether esters in a ring-opening copolymerization even at reaction temperatures above the ceiling temperature of the cyclic ether. The course of the individual steps of the copolymerization and the mechanism of the propagation reaction were investigated measuring the kinetics of the copolymerization THF/succinic anhydride (BSA) and of a model reaction THF/acetic anhydride (ESA) and determining the overall composition of the reaction products. The kinetic experiments showed, that the nucleophilic attack of THF on the anhydride oxonium ion determines the rate of the propagation reaction and that the reactivities of the two anhydride oxonium ions towards THF differ by a factor of about 25 (…[-ESA]⊖ 〉 …[-BSA]⊕). From the composition of the reaction products obtained above the ceiling temperature of THF the relative reactivities of the two monomers THF and anhydride in the competitive additions to the oxonium ion … - CO[-THF]⊕ have been calculated to the result, that BSA is about two times as reactive as ESA.
    Notizen: Die kationisch initiierte Reaktion von Tetrahydrofuran (THF) mit Dicarbonsäureanhydriden führt unter ringöffnender Copolymerisation selbst bei Reaktionstemperaturen oberhalb der Ceilingtemperatur des Ringäthers zu Polyätherestern. Der Verlauf der einzelnen Reaktionsschritte der Copolymerisation und der Mechanismus der Wachstumsreaktion wurden durch kinetische Untersuchungen der Copolymerisationsreaktion THF/Bernsteinsäureanhydrid (BSA) sowie einer Modellreaktion THF/Essigsäureanhydrid (ESA) und durch Bestimmung der Zusammensetzung der Reaktionsprodukte ermittelt. Die kinetischen Versuche ergaben, daß der nukleophile Angriff von THF an ein Oxoniumion des Anhydrids die Geschwindigkeit der Wachstumsreaktion bestimmt und daß sich die Reaktivitäten der beiden Anhydrid-Oxoniumionen gegenüber einem THF-Angriff um einen Faktor von ca. 25 voneinander unterscheiden (…[-ESA]⊖ 〉 …[-BSA]⊕). Aus der Zusammensetzung der Reaktionsprodukte oberhalb der Ceilingtemperatur von THF konnten die relativen Reaktivitäten der beiden Monomeren, THF und Anhydrid, in den konkurrierenden Anlagerungsschritten an das THF-Oxoniumion …[-CO-TH́F]⊕ ermittelt werden. Danach ist BSA um den Faktor 2 reaktiver als ESA.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 97
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: The polymerization of vinyl monomers in the presence of an amino acid ester and cupric ion in dimethyl sulfoxide at 50°C was studied. The polymerization was found to follow the free radical mechanism, the rate being proportional to the monomer concentration and to the square root of the initiator concentration. Using an amino acid in conjunction with cupric ion, no polymerization was observed. The overall activation energy for the polymerization of methyl methacrylate was found to be ca. 9.5 kcal/mole. Effects of the nature of cupric salts, of the monomer, and of solvents on the polymerization were examined.
    Notizen: Die Polymerisation von Vinylmonomeren wurde mit dem System Aminosäureester/Kupfer(II)ion in Dimethylsulfoxidlösung bei 50°C untersucht. Es ergab sich, daß die Polymerisation radikalisch verläuft und die Geschwindigkeit der Anfangskonzentration des Monomeren und der Quadratwurzel aus der Initiatorkonzentration proportional ist. Mit dem System Aminosäure/Kupfer(II)ion konnte keine Polymerisation beobachtet werden. Die Aktivierungsenergie der Polymerisation des Methylmethacrylats beträgt ca. 9,5 kcal/Mol. Ferner wurden die Effekte von verschiedenen Kupfersalzen, Monomeren und Lösungsmitteln geprüft.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 98
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 150 (1971), S. 57-62 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: The preparation and the free radical polymerization of N-(4-diphenylamino)acryl amide and of the analogous methacryl amide are described. By oxidation of the poly-N-(4-diphenylamino)acryl amide with lead dioxide a polyradical with diphenylnitroxyl units was obtained instead of the expected polymeric diphenylnitrogen radical.
    Notizen: Die Herstellung und die radikalische Polymerisation von N-(4-Diphenylamino)-acrylamid und N-(4-Diphenylamino)-methacrylamid werden beschrieben. Durch Oxydation des Poly-N-(4-diphenylamino)-acrylamids mit Bleidioxid erhält man nicht das erwartete polymere Diphenylstickstoffradikal, sondern ein Polyradikal mit Diphenylstickoxidgruppen.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 99
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 150 (1971), S. 63-71 
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: The structure of glycogen and of starlike molecules with grafted amylose chains and glycogen as kernel is studied by the uptake of iodine and by light scattering measurements of carbanilate derivatives.The structure of four branching models, partly used by ERLANDER and FRENCH in previous studies was calculated on the basis of the theory of cascade processes developed by GOOD and by GORDON. By comparison of the experimental data with these four models the number of grafted chains, the chain length, and the structure of glycogen could be determined. The results indicate strongly a regular structure for the glycogen kernel.The weight fraction of the grafted chains, determined by light scattering, is for the high molecular weight compounds in good agreement with the ratio of iodine uptake of the branched product to linear amylose. Both values deviate, however, with decreasing molecular weight.
    Notizen: Die Struktur von Glykogen und von Sternmolekülen mit aufgepfropften Amyloseketten und Glykogen als Kern wurde durch die Jodaufnahme und durch Lichtstreuungsmessungen an den Tricarbanilaten untersucht.Unter Anwendung der von GOOD und von GORDON entwickelten Theorie der Kaskadenprozesse wurden für vier verschiedene Verzweigungsmodelle, die teilweise auf einer früheren Arbeit von ERLANDER und FRENCH basieren, Strukturberechnungen durchgeführt. Aus einem Vergleich der experimentellen Werte mit diesen vier Modellen konnte die Zahl der aufgepfropften Ketten, ihre Kettenlänge und die Struktur des Glykogenkerns bestimmt werden. Die Ergebnisse lassen auf eine sehr regelmäßige Struktur des Glykogenkerns schließen.Zwischen dem aus der Lichtstreuung bestimmten Gewichtsanteil der aufgepfropften Ketten und dem aus der potentiometrischen Jodtitration ermittelten Wert (Verhältnis der Jodaufnahme der verzweigten Produkte zu Amylose als Bezugssubstanz) besteht bei den hochmolekularen Substanzen eine gute Übereinstimmung; mit abnehmendem Molekulargewicht treten jedoch zunehmend Abweichungen auf.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 100
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Beschreibung / Inhaltsverzeichnis: Linear oligourethanes with phenylurethane endgroups and cyclic oligourethanes were prepared from diethylene glycol and hexamethylene diisocyanate. The largest ring synthesized contains seven units of each, i.e., 119 ring atoms, with a molecular weight of 1920.An effective separation of the oligomers was achieved by adsorption column chromatography. An eluting solvent with solvent gradient was applied successfully. Melting points, transitions, long periods, and X-ray diffraction of the oligomers prepared are discussed with regard to their structure.
    Notizen: Es wurden lineare Oligourethane mit Phenylendgruppen und cyclische Oligourethane aus Diäthylenglykol und Hexamethylendiisocyanat dargestellt. Der größte bisher isolierte Ring enthält je sieben Grundbausteine und besitzt 119 Ringglieder bei einem Molekulargewicht von 1920.Eine gute Trennung der Oligomeren wurde durch Adsorptionssäulenchromatographie erzielt. Hierbei wurde ein Elutionsmittel mit Lösungsmittelgradient verwendet. Schmelzpunkte, Umwandlungserscheinungen, Langperioden und Weitwinkeldiagramme der Oligomeren werden im Hinblick auf ihre Struktur diskutiert.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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