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  • 1
    Electronic Resource
    Electronic Resource
    Theory of thermal decomposition and volatilization of normal alkanes and linear polyethylene (1979)
    Springer
    Polymer bulletin 1 (1979), S. 347-354 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The fragmentation of linear polyethylene of high molecular weight, of normal alkanes, and of other nonbranched poly- α- olefins in a pyrolyzer connected with a gas chromatograph was studied previously. From the evaluation of the fragments longer than C11 or than the respective pentamer random decomposition process was suggested for these polymers. This process was described with characteristic cleavage probabilities for the C-C-bonds in the backbone of the chain. It is not possible to apply this simple model to the decomposition of normal alkanes without consideration of the volatilization. An approach to this problem is presented in this paper.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01045423
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  • 2
    Electronic Resource
    Electronic Resource
    Zur Ermittlung der Äthylen-Sequenzlängenverteilung und der chemischen Uneinheitlichkeit in Copolymeren mit Propylen durch Pyrolyse-Gas-Chromatographie (1975)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 276 (1975), S. 267-277 
    Details
    ISSN: 1618-2650
    Keywords: Untersuchung von Äthylen-Propylen-Copolymeren, Propylen-Äthylen-Copolymeren ; Chromatographie, Gas/Chromatographie, Gel ; Pyrolyse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Äthylen-Propylen-Copolymere wurden hinsichtlich Sequenzverteilung des Äthylens durch Pyrolyse gekoppelt mit Gas-Chromatographie analysiert. Die untersuchten Copolymeren waren mit löslichen Ziegler-Natta-Katalysatoren hergestellt und von verschiedenem Kristallisationsgrad. Bei einer Serie waren die Methylgruppen der Propyleneinheiten radioaktiv markiert. Es war somit möglich, mit dem Flammenionisationsdetektor (FID) und gleichzeitig mit dem parallelgeschalteten Strahlungsdetektor diese Methylgruppen nachzuweisen. Die Auswertung der n-Alkane und der Methylalkane in beiden Detektoren ergab Übereinstimmung mit der Kinetik. Die Methode eignet sich gut für lange Sequenzen. Gel-chromatographische Fraktionierung der Copolymeren ergab eine Heterogenität in der chemischen Zusammensetzung. Die eine Komponente ist hochmolekular, während die andere ein Molekulargewicht von weniger als 1000 besitzt und fast kein Propylen enthält. Es wird diskutiert, wie sich chemische Uneinheitlichkeit bei der Kinetik und bei der Pyrolyse auf die Ermittlung der Sequenzverteilung auswirkt. Ein Mechanismus, bei dem von verschiedenen Zentren Ketten mit verschiedener chemischer Zusammensetzung erzeugt werden, wird als Modell angenommen. Die experimentellen Ergebnisse zeigen, daß die Uneinheitlichkeit sich nicht kritisch auf die Bestimmung der Sequenzverteilung auswirkt.
    Notes: Abstract Pyrolysis coupled with gas chromatography has been applied to investigate the sequence distribution in copolymers of ethylene and propylene. The copolymers analyzed have been prepared with soluble Ziegler-Natta-catalysts and show different degrees of crystallinity. In one series of samples the methyl group of the propylene units has been labeled with tritium. It was then possible to detect carbons by flame ionization detector and simultaneously the methyl groups by the radio-detector in parallel. Within the errors of these methods the results from both detectors are consistent with the calculations from kinetics. The accuracy of the data is best in copolymers with long ethylene sequences. By GPC fractionation a heterogeneity in the chemical composition can be observed. One component of the copolymers is of high molecular weight, while the other has a molecular weight of less than 1000 and is very rich in ethylene. The influence of chemical heterogeneity on sequence distribution derived from kinetics and pyrolysis has been discussed. A mechanism in which chains with different chemical composition are growing from different species of the catalyst has been proposed. The experimental results show that the heterogeneity is not critical for the sequence analysis by kinetics and pyrolysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00430984
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  • 3
    Electronic Resource
    Electronic Resource
    Radiation induced cis-trans isomerization of swollen polybutadiene networks (1978)
    Springer
    Polymer bulletin 1 (1978), S. 161-165 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The kinetics of the radiation induced cis- trans- isomerization of cis- 1,4- polybutadiene gel swollen in toluene were studied by using diphenyl disulfide as sensitizer. The reaction follows first order kinetics. The values of the pseudo first- order rate constant of the isomerization vary with the crosslink density of the network. After correction for the degree of swelling, however, the isomerization reaction turns out to be independent of the crosslink density and proceeds with the same efficiency as in solution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00283064
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  • 4
    Electronic Resource
    Electronic Resource
    Thermoelastic studies on polybutadiene networks (1978)
    Springer
    Polymer bulletin 1 (1978), S. 211-214 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary An unequivocal correlation between the first coefficient of the Mooney-Rivlin equation and the degree of swelling is concluded from stress- strain measurements of cis- trans isomerized polybutadiene networks of varying cis- contents and from corresponding swelling measurements. The second coefficient turns out to be approximately constant, which means that the polymer network is not affected critically by the irradiation although the crosslink density diminishes. The temperature dependence of the unperturbed dimensions of the network was determined to be positive in the higher cis- region and to be negative at higher trans contents. A linear correlation was found with the amount of trans.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00283072
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  • 5
    Electronic Resource
    Electronic Resource
    Beziehungen zwischen Molekularbewegung und Kettenstruktur in Styrol/Butadien-Copolymeren durch Messungen der 13C-Spin-Gitter-RelaxationHerrn Prof. Dr. H. Mark zum 80. Geburtstag mit den besten Wünschen gewidmet (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 485-490 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: By measurements of the 13C spin lattice relaxation times (T1) of single 13C nuclei in solutions of random and blocklike styrene/butadiene-copolymers, polystyrene, and polybutadiene, it is shown that the segmental motion is influenced by the sequence distribution. The T1-values of 1,4-butadiene monomeric units at boundaries with styrene or with 1,2-butadiene units are different from the T1-values of 1,4-butadiene units in block sequences. Local conformational changes dependent on the structure of succeeding monomeric units must, therefore, contribute to the 13C spin lattice relaxation. In the styrene/butadiene-copolymers, the relaxation of the ortho-phenyl C-atoms is slower than the para-phenyl relaxation. This is interpreted by a rotational motion of the phenyl ring about the C-phenyl bond connecting it to the chain backbone. This rotational motion is about four times slower than the segmental motion.
    Notes: Durch Messung der 13C-Spin-Gitter-Relaxationszeiten (T1) einzelner 13C-Kerne in Lösungen von statistischen und blockartigen Styrol/Butadien-Copolymeren, Polystyrol und Polybutadien zeigt sich, daß die Segmentbewegung durch die Sequenzlängenverteilung beeinflußt wird. Die T1-Werte der 1,4-Butadienstruktureinheiten an Nahtstellen mit Styrolbzw. 1,2-Butadieneinheiten unterscheiden sich von den T1-Werten der 1,4-Butadieneinheiten in Blocksequenzen. Zur 13C-Spin-Gitter-Relaxation tragen daher lokale, von der Struktur aufeinanderfolgender Monomerbausteine abhängige Konformationsänderungen bei. In den Styrol/Butadien-Copolymeren erfolgt die Relaxation der ortho-Phenyl-C-Atome langsamer als die para-Phenyl-Relaxation. Die wird gedeutet durch eine Rotationsbewegung der Phenylringe um die Achse, die durch die Bindung zwischen Phenyl und Kette gegeben ist. Die Rotation verläuft etwa viermal langsamer als die Segmentbewegung.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.020011975133
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  • 6
    Electronic Resource
    Electronic Resource
    Zur strukturbestimmung des 1,4-poly(2,3-dimethyl-1,3-butadien)s durch 13C NMR-spektroskopieHerrn Prof. Dr. H. Kämmerer zu seinem 65. Geburtstag mit unseren besten Wünschen gewidmet (1977)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 178 (1977), S. 557-563 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: cis and trans Configuration of monomeric units in 1,4-poly(2,3-dimethyl-1,3-butadiene), poly(1,2-dimethyl-1-butenylene), has been determined by 13C NMR spectroscopy.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1977.021780225
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  • 7
    Electronic Resource
    Electronic Resource
    Determination of configuration and conformation of polymer segments by low-molecular-weight diastereomeric model compounds (1978)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 823-827 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1978.021790325
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  • 8
    Electronic Resource
    Electronic Resource
    NMR - studies on conformation and dynamics of macromolecules with emphasis on their configuration (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 3 (1979), S. 319-326 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 1Capabilities and limitations of methods for the determination of unperturbed macro - conformations in Θ - solutions as well as in metls and glasses are discussed, especially concerning the consequences for the micro-conformations. Quasi - isoenergetic polymer chains are concluded from thermolastic measurements on a configurätional copolymer.2Temperature dependent NMR- chemical shift measurements - beside those of coupling constants - are proposed for an independent determination of the micro - conformation on at a segemental level. Their populations are calculable from slow as well as from fast exchange spectra. Macro- dimensions as well as their temperature dependence as the consequence of the micro - conformations.3The dynamics of macromolecular chains - especially the anisotropy of motion - are discussed from NMR data.4The mechanism of stereospecific polymerizations as a consequence of conformational arrangements is discussed from NMR measurements.5Approaches to interpret thermal and mechanical data from configuration and conformation are reported.A short survey of the IUPAC lecture is presented, since detailed interpretation of the scientific work discussed either is given in the literature or will be published in the near future.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.020031979116
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  • 9
    Electronic Resource
    Electronic Resource
    One and two component hydrogels, 3Part 2: cf.2. Deswelling and compression measurements on one component hydrogelsDedicated to Prof. Dr. G. Meyerhoff on the occasion of his 60th birthday (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 2605-2613 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The value of the Flory-Huggins interaction parameter for water and poly(N-vinyl-2-pyrrolidone)Systematic nomenclature: Poly[l-(2-oxo-l-pyrrolidinyl)ethylene]. (PVP), networks is determined by combining uni-directional compression measurements in the swollen state with network deswelling measurements. It was found that the dependance of the parameter on crosslink density can be explained by considering the interaction of water with the crosslinking molecule, a very water insoluble compound. Moreover, it was found that the interaction parameter within the swelling range studied is independant of network concentration. The number of elastically effective network chains is overestimated by a substantial margin.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.021801105
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  • 10
    Electronic Resource
    Electronic Resource
    Herstellung radioaktiv markierter äthylen/propylen copolymerer. Berechnung der primärstruktur aus kinetischen datenVorgetragen beim Makromolekularen Kolloquium, Freiburg i. Br. 1971, cf.4.Herrn Prof. Dr. G. V. Schulz zu seinem 70. Geburtstag mit allen guten Wünschen gewidmet (1976)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 177 (1976), S. 1051-1061 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: A synthesis method for ethylene/propylene copolymers labelled with tritium at the α-methyl groups was worked out. The activity is sufficient for a detection of the pyrolysis products in a Geiger counter. The sequence distribution of copolymers prepared with Ziegler-Natta catalysts was calculated from kinetic measurements. Studies on mechanisms of thermal decomposition in such copolymers as well as on the application of pyrolysis to determine the distribution of chemical sequences shall be discussed in further reports.
    Notes: Eine Synthese für an der α-Methylgruppe mit Tritium markierten Äthylen/Propylen-Co-polymeren wurde ausgearbeitet. Deren Aktivität ist für die Messung der pyrolytischen Spaltprodukte in einem Durchfluß-Zählrohr ausreichend. Die Sequenzlängenverteilung der mit löslichen Ziegler-Natta-Katalysatoren hergestellten Copolymeren wurde aus der Kinetik berechnet. Über Untersuchungen der thermischen Spaltungsmechanismen in solchen Copolymeren und die Pyrolyse zur Bestimmung der Sequenzlängenverteilung wird in Kürze berichtet.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1976.021770408
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