bluuebunny/crossref_metadata_2025_split huggingface dataset:
Untersuchungen zum oxidativen Abbau nativer Cellulose, 3. Polymerisationsgrad und Polymerisationsgrad‐Verteilungen im Verlauf des Abbaus von Alkalicellulose durch Sauerstoff
Authors: Jovanović S. , Palma A. , Schulz G. V. 
Published: April 2003

AbstractDer zeitliche Ablauf des oxidativen Abbaus von Cellulose wird unter standardisierten Bedingungen durch Messung des Zahlenmittels, Pn (osmotisch), des Gewichtsmittels Pw (Lichtstreuung, Viskosität) und der Verteilungen des Polymerisationsgrades gemessen. Die Bildung der Spaltstellen verläuft in 2 Stufen mit den unterschiedlichen Geschwindigkeitskonstanten k1 und k2. Diesem Prozeß überlagert sich am Anfang die Bildung intramolekularer Vernetzungsstellen. Unter Verwendung der Statistik vernetzter Moleküle von Stockmayer ergeben sich Beziehungen, welche es erlauben, aus dem Zeitablauf von Pn und Pw die Zahlenwerte von k1, k2 und die Zahl der Vernetzungsstellen zu bestimmen. Pro natives Cellulosemolekül mit Pn=Pw=1,35·104 bilden sich unter den angegebenen Bedingungen durchschnittlich 4 Vernetzungsstellen.Sowohl die Zeitkurven als auch die Verteilungen des Polymerisationsgrades geben keinen Hinweis darauf, daß in der native Cellulose bereits „Lockerstellen”︁ vorhanden sind.
Statistical analysis of experimental data from polymers in dilute solutions, 1. Dependence of linear expansion factors of poly(methyl acrylate) on molecular weight
Authors: Guaita Marino , Chiantore Oscar 
Published: April 2003

AbstractThe theoretical relationships by Flory, Kurata‐Stockmayer, Stockmayer‐Fixman, and Ptitsyn, between the linear expansion factor of polymer coils and molecular weight are applied to poly(methyl acrylate) fractions. By employing statistical procedures, it is shown that the Flory relationship represents only a crude approximation, whereas those by Kurata‐Stockmayer, Stockmayer‐Fixman, and Ptitsyn have to be considered as satisfactory mathematical models.
Polymerization of cis‐ and trans‐7,9‐dioxabicyclo [4.3.0] nonane
Authors: Kops Jørgen , Spanggaard Hans 
Published: April 2003

AbstractThe polymerization of cis‐ and trans‐7,9‐dioxabicyclo[4.3.0]nonane (1a) and (1b) was investigated in bulk and in solution with phosphorus pentafluoride and triethyloxonium hexachloroantimonate as initiators. The cis‐isomer 1a forms in high yield the cyclic dimer 2a. The trans‐isomer 1b polymerizes readily under similar conditions to relatively low molecular weight polymers, whereas in 1,1,2,2‐tetrachloroethane solution predominantly the cyclic dimer 2b is formed. The polymerization of the trans‐isomer 1b in toluene‐d8 solution is of first order with respect to monomer, and the concentration of active species appears to remain constant throughout the reaction. The polymerization of 1b in toluene‐d8 with PF5 as initiator is completely reversible with temperature change, and the standard ceiling temperature T is 118°C (cone.: 1 mol/dm3 in toluene‐d8). The cyclic dimer 2b polymerizes at −25°C to the same equilibrium product composition as the corresponding monomer 1b.
Über poly(1,3,5‐triazin)e und poly(1,2,4‐triazin)e
Authors: Wahl Bernd , Wöhrle Dieter 
Published: April 2003

AbstractDurch Polycyclokondensation von Terephthalamidrazon mit 1,2‐Diketonen wurden in hohen Ausbeuten niedermolekulare und polymere 1,2,4‐Triazine dargestellt. Die Umsetzung von Amidinen wie Terephthalamidin mit Aldehyden ergab in einer Polycyclokondensation niedermolekulare und polymere 1,3,5‐Triazine. Thermische Analysen der Poly(1,2,4‐triazin)e und der Poly(1,3,5‐triazin)e wurden durchgeführt und die Pyrolysemassenspektren dieser Verbindungen aufgenommen.
Polymerizability of methyl substituted 1,3‐dioxolanes
Authors: Okada Masahiko , Mita Koji , Sumitomo Hiroshi 
Published: April 2003

AbstractThe polymerization of 4‐methyl‐, 4,4‐dimethyl‐, cis‐4,5‐dimethyl‐, and trans‐4,5‐dimethyl‐1,3‐dioxolanes was investigated with boron trifluoride etherate and the perchloric acid‐acetic anhydride binary system as initiators. The polymerization of 4‐methyl‐1,3‐dioxolane (1) involves an equilibrium between monomer and polymer, and the polymer consists of alternating oxypropylene and oxymethylene units. The thermodynamic parameters for the polymerization were determined from the temperature dependence of the equilibrium monomer concentrations in the temperature range from −20 to 5°C: ΔH1c = −3,2±0,2kcal/mol and ΔS = −12,7±0,8 cal mol−1 K−1. Dimethyl substituted 1,3‐dioxolanes are very reluctant to polymerize: only a liquid oligomer was obtained in poor yield from cis‐4,5‐dimethyl‐1,3‐dioxolane, and neither polymer nor oligomer was produced from 4,4‐dimethyl‐ and trans‐4,5‐dimethyl‐1,3‐dioxolanes at temperatures above −;78°C. The effect of methyl substituents on the cationic polymerizability of 1,3‐dioxolanes is discussed from the thermodynamic point of view.
Effect of molecular weight distribution of the original polymer on separation characteristics in successive solutional fractionation
Authors: Kamide Kenji , Miyazaki Yukio 
Published: April 2003

AbstractAn attempt has been made to clarify the effect of molecular weight distribution (MWD) in the original polymer on the separation characteristics in successive solutional fractionation (SSF) and comparisons were made with successive precipitational fractionation (SPF). Polymers with Schulz‐Zimm distribution and Wesslau distribution of the degree of polymerization (ratio of the weight‐ to number‐average degree of polymerization, X̄/X̄ = 2 to 5) were brought into solution, and cooled to cause precipitation according to the modified simulative procedure of Kamide and Sugamiya, based on the Flory‐Huggins's theory of dilute solutions of polymers. No double‐peak distributions were observed in the fractions obtained by SSF under the conditions which give double‐peak distributions in the case of SPF. The minimum value of X̄w in the fractions obtained in a given run is almost the same for SSF and SPF, the minimum increasing with decreasing X̄/X̄ (the suffix zero denoting the original polymer). The ratio X̄w/X̄n in the fractions is not greatly influenced by X̄/X̄ except for the first few fractions. The standard deviation σ′ of the MWD in the fractions decreases with increasing X̄/X̄ in an initial stage, while this situation is reversed in the later stages. In general SSF furnishes sharp fractions regardless of X̄/X̄.
The Cu‐catalyzed oxidative polymerization of phenols
Authors: Tsuchida Eishun , Nishide Hiroyuki , Nishiyama Toshio 
Published: April 2003

AbstractThe reactivity of phenols in the Cu complex catalyzed oxidation was studied by measuring the oxidation rate, the rate constant of the electron‐transfer step (Ke), and the reduction potential of the Cu complex (Ered). Linear relationships were observed between log Ke and the logarithm of the oxidation rate, Ered, and Hammett's σ value of the phenol. The larger Ke values were obtained in the oxidation of the ε‐conjugated 2,6‐diphenylphenol, and in the oxidations with the Cu complexes involving pyridine derivatives. It was found that for each case there is a most suitable pair of a Cu catalyst and a phenol to produce a polymeric phenylether in high yield, i.e. an oxidation product is predictable from Ered of the catalyst and the σ value of the phenol. On the other hand, p‐substituted phenols could be polymerized only by strong oxidizing agents.
Operating conditions for preparative successive solutional fractionation, 2. Miscellaneous factors including experimental performance, a modified procedure, and repetition of fractionation
Authors: Kamide Kenji , Miyazaki Yukio 
Published: April 2003

AbstractPreparative successive solutional fractionation (SSF) of macromolecules has been rigorously computerized on the basis of a modified Flory‐Huggins polymer dilute solution theory. The polymers having Schulz‐Zimm and Wesslau distributions with the weight‐to number‐average degree of polymerization X̄0w/X̄0n = 2–5 and X̄0w = 300 have been employed for this purpose. Accurate control of amount of fractions, Q, and separation of two solution phases (i.e., a polymer‐lean phase and a polymer‐rich phase) were much more easy in SSF as compared to successive precipitational fractionation (SPF). Effect of the concentration dependence parameter p of the polymer/solvent thermodynamic interaction parameter χ on the molecular weight distribution (MWD) of the fractions have been examined in detail. A new modified SSF procedure was proposed in order to reduce the volume of solvent necessary for a single run. The relationships between initial concentration, amount of fraction Q and X̄w/X̄n for the first fractions isolated by SSF were established for the case where the original polymer had Schulz‐Zimm and Wesslau distributions. In SSF repetition of fractionation was absolutely ineffective in contrast to SPF.
X‐ray structural studies of the atactic polymers poly(1‐methylhexamethylene), poly(1‐methyloctamethylene), poly(1‐methyldecamethylene), and poly(1‐methyldodecamethylene), model polymers of ethylene/propene‐copolymers
Authors: Bassi Ivano W. , Scordamaglia Raimondo 
Published: April 2003

AbstractPoly(1‐methylhexamethylene) (1a), poly(1‐methyloctamethylene) (1b), poly(1‐methyldecamethylene) (1c), and poly(1‐methyldodecamethylene) (1d) were studied by high‐angle X‐ray diffraction methods. The polymers reveal a partial intramolecular and intermolecular order and may be considered as ethylene/propene copolymers containing, along the chains, regular sequences of 2,3,4, and 5 ethylene units every propylene unit, respectively.Configurational disorder at the tertiary carbon atoms was evidenced so that the polymers are atactic. In the ordered regions, the backbone chains assume planar zig‐zag conformations. The packing of the macromolecules is conditioned by the side methyl groups, and their influence increases going from 1d to 1a.An intermolecular “long range order” was evidenced for the backbone chains, while + an intermolecular “short range order” is present for the methyl side groups. The structures proposed for these polymers seem to be possible also for ethylene/propene +dom copolymers having similar compositions.The low and high‐temperature structures of propene/butadiene alternating copolymers are also described.
The thermodynamics of polymerisation of aldehydes and cyclic ethers, 4.1,3‐dioxocane and 1,3,6‐trioxocane
Authors: Busfield W. Kenneth , Lee R. Martin 
Published: April 2003

AbstractThe equilibrium between gaseous monomer (g) and amorphous polymer (c) has been studied for 1,3‐dioxocane and 1,3,6‐trioxocane between 100 and 137°C. From the equilibrium pressures of monomer, the ΔH and ΔS values have been calculated. Thermodynamic data for the vaporisation of each monomer have also been measured so that values of ΔH and ΔS for the polymerisations could be calculated (l: liquid phase).
For 1,3‐dioxocane:

For 1,3,6‐trioxocane:
Study on the possibility of reverse‐order fractionation in successive precipitational fractionation
Authors: Kamide Kenji , Miyazaki Yukio 
Published: April 2003

AbstractAn attempt has been made to account for the occurrence of reverse‐order fractionation (ROF) phenomena in successive precipitational fractionation (SPF) in terms of the newly established rigorous fractionation theory, assuming complete thermodynamic equilibrium conditions between a polymer‐rich phase and a polymer‐lean phase and to throw light on operating conditions under which ROF occurs. For this purpose, the simulation technique was employed. ROF occurs not only between 1st and 2nd fractionation steps but also between two successive higher order steps even under thermodynamic equilibrium state. The molecular weight distribution of the original polymer contributes very sensitively to ROF: For the Schulz‐Zimm type polymer ROF is highly observed at a large amount of fraction Q in a narrow range of initial concentration v whereas for the Wesslau type polymer large ROF occurs at small Q over a relatively wide v range. In general, there exist appropriate ranges of the weight‐average degree of polymerization of the initial polymer X̄ the solvent nature expressed by the concentration dependence of the polymer/solvent interaction parameter p, and the initial polymer concentration v for ROF. A broad original polymer gives rise to large ROF. The theoretical predictions obtained here can explain very clearly the experimental results by Fujisaki and Kobayashi concerning the effect of X̄, p, and v on ROF in SPF of polyacrylonitrile.
Orientierungsmessungen an uniaxial verstreckten polyacrylnitrilfilmen
Authors: Siesler Heinz Wilhelm 
Published: April 2003

AbstractAus dreidimensionalen Untersuchungen von uniaxial verstreckten Polyacrylnitrilfilmen mit linear polarisierter IR‐Strahlung werden Orientierungsparameter der v(CN)‐ und δ(CH2)‐Absorptionsbanden in den drei Filmkoordinatenrichtungen abgeleitet. In Verbindung mit Röntgenbeugungsaufnahmen werden Rückschlüsse auf den Typ und Grad der bei der Verstreckung auftretenden molekularen Orientierung gezogen.
Darstellung und spektroskopische analyse von oligo{[4‐(1,1,3,3‐tetramethylbutyl) (bzw. 4‐octyl)‐2‐hydroxy‐1,3‐phenylen]methylen}en und ihrer Ausgangsverbindungen
Authors: Kämmerer Hermann , Eberle Klaus , Böhmer Volker , Großmann Max 
Published: April 2003

Abstract4‐(1,1,3,3‐Tetramethylbutyl)phenol und 4‐Octylphenol, erhalten durch Friessche Verschiebung der entsprechenden Phenylester und anschließende Reduktion der Carbonylgruppe, wurden in ortho‐Stellung monobromiert und mit Formaldehyd hydroxymethyliert. Aus diesen Verbindungen konnten sechs 2,2′‐Methylendiphenole (2a–f) sowie sieben 2,6‐Bis(2‐hydroxybenzyl)phenole (3a–g) dargestellt werden, die in 4‐Stellung zu den phenolischen Hydroxygruppen Methyl‐, 1,1,3,3‐Tetramethylbutyl‐ und Octyl‐Substituenten in verschiedenen Verhältnissen enthalten. Die IR‐ und 1H‐NMR‐spektroskpischen Analysen bestätigten die angegebenen Strukturen der dargestellten phenolischen Mehrkernverbindungen.
High resolution 1H‐NMR study of association of polymers in solution. Poly(methyl methacrylate) and poly(vinyl chloride)
Authors: Spěváček Jiří , Schneider Bohdan 
Published: April 2003

AbstractA procedure for the determination of the contents and the thermal stability of associated structures in solutions of polymers is described, making use of the anomalous values and changes of integrated band intensities in high‐resolution 1H‐NMR spectra. In this way, associated structures in solutions of isotactic and syndiotactic poly(methyl methacrylate), (PMMA), were detected and characterized. The associated structures in solutions of isotactic PMMA are much more stable than the aggregates in solutions of the syndiotactic PMMA. Two types of aggregates differring in stability were also observed in solutions of atactic poly(vinyl chloride).
Enthalpies of dilution of poly(1‐vinyl‐2‐pyrrolidone) + aqueous methanol solution
Authors: Murakami Sachio , Kimura Fumio , Fujishiro Ryoichi 
Published: April 2003

AbstractEnthalpies of dilution of poly(1‐vinyl‐2‐pyrrolidone), (poly[1‐(2‐oxopyrrolidin‐1‐yl)ethylene]), in aqueous methanol solutions of different methanol contents were measured at 298 K. The molecular weight of the polymer was 10000 and 40000, respectively.The experimental results were analysed with a modified Tompa formula containing an interaction parameter dependent on concentration; so the interaction parameter at infinite dilution between the polymer and the mixed solvent was derived.The influence of methanol on the interaction between polymer and water molecules was discussed from the change of the interaction parameter at infinite dilution for the transfer process from water to aqueous methanol solvent.
Infrared spectroscopic studies on polyethylene, 2. The characterisation of specific types of alkyl branches in low‐branched ethylene polymers and copolymers
Authors: McRae Margaret A. , Maddams William F. 
Published: April 2003

AbstractBands characteristic for some specific branches have been found in two regions of the IR spectra of near linear polyethylenes made by the Phillips process. Polymers with methyl branches give a band at 935 cm−1, probably the methyl rocking mode. The intensity of this band is proportional to the methyl branch content, thus providing a quantitative method for its estimation. No band specific for ethyl branches has been found, but propyl and longer branches show one at 890 cm−1 and this is also assigned to the rocking mode. This band is observed more readily if the polymers are brominated at ambient temperature, to remove interfering unsaturation bands. The results for methyl and ethyl branched near linear polymers differ significantly from those obtained with polypropylene, poly(1‐butene), and ethylene copolymers with high concentrations of methyl and ethyl branches. This is very probably the result of the presence of blocks of the repeating unit CH2CH(R) in the latter materials. Methyl branched polymers show a band at 1150 cm−1, assigned to the methyl wagging mode of branches present in the crystalline phase. Its intensity is proportional to the methyl branch content and it may be used for quantitative purposes. Ethyl and longer branches do not give a methyl wagging band of detectable intensity.
Metallkomplexe mit polymeren liganden, 13. Poly(4‐pyridyläthylen) als ligand in metallkomplexen mit einem oder zwei zentralmetallen
Authors: Biedermann Hans‐G. , Seidl Peter 
Published: April 2003

AbstractAtaktisches Poly(4‐pyridyläthylen) (1) bildet mit zahlreichen Metallchloriden in Äthanol Komplexe mit verschiedenen Koordinationszahlen in Abhängigkeit vom eingesetzten Metallion. Komplexierungsreaktionen mit zwei Metallchloriden gleichzeitig führen je nach Reaktionsbedingungen zu Komplexen unterschiedlicher Zusammensetzungen. IR‐Spektren, elektrische Leitfähigkeit und das magnetische Verhalten werden diskutiert.
Polymerization of acrylonitrile initiated by 2‐tetrazene/haloacetic acid systems
Authors: Sugiyama Kazuo 
Published: April 2003

AbstractThe polymerization of acrylonitrile initiated by binary 2‐tetrazene/haloacetic acid systems was studied in N,N‐dimethylformamide (DMF). A kinetic investigation was also undertaken of decomposition of 2‐tetrazenes in the presence of various haloacetic acids in DMF. The decomposition rate decreased with increasing halogen‐carbon bond energy of the haloacetic acid.
Kinetik der bromierung von phenolen und phenolischen mehrkernverbindungen, 2. Die reaktionsfähigkeit isomerer zweikernverbindungen
Authors: Böhmer Volker , Niemann Wilhelm 
Published: April 2003

AbstractDie Geschwindigkeit der Bromierung von 6 isomeren Zweikernverbindungen mit jeweils einer reaktionsfähigen Stelle (Hydroxydimethylbenzyl‐methylphenole 1, 2 und 3) wurde in Eisessig bei 22°C UV‐spektroskopisch bestimmt. Für die Reaktion in ortho‐Stellung zur phenolischen Hydroxy‐Gruppe ergibt sich eine Verminderung der Geschwindigkeit um den Faktor 3–3,5 wenn zwischen den Hydroxy‐Gruppen der beiden Phenolbausteine eine intramolekulare Wasserstoffbrücke sterisch möglich ist (1a). In den anderen Fällen (1b, 2a, 2b) verläuft die Bromierung ungefähr ebenso schnell wie bei 2,4‐Dimethylphenol. Die schneller verlaufende Reaktion in para‐Stellung (3a, 3b) wird durch eine Wasserstoffbrücke um den Faktor 1,4 verlangsamt. Das Verhältnis der Geschwindigkeitskonstanten für den Term dritter und zweiter Ordnung, k3/k2, ist bei allen Verbindungen annähernd gleich. Man mußannehmen, daß durch eine Wasserstoffbrücke zwischen den phenolischen Hydroxy‐Gruppen Elektronenpaare am Sauerstoffatom des reagierenden Bausteins blokkiert werden, was über einen geringeren + M‐Effekt zu einer Verminderung der Elektronendichte dieses aromatischen Systems führt.
The conformational transition in poly(methacrylic acid) and butyl vinyl ether/maleic anhydride copolymers studied by 1H NMR linewidth measurements
Authors: Kay Peter J. , Kelly David P. , Milgate Geoffrey I. , Treloar F. Edward 
Published: April 2003

AbstractLinewidth measurements on the 1H NMR spectra of D2O solutions of poly(methacrylic acid), (PMA), and the hydrolyzed form of butyl vinyl ether/maleic anhydride copolymer show a sharp decrease in the linewidths of side chain resonances at a degree of neutralization α ≈ 0,2. This is the region in which potentiometric titrations previously have shown a conformational transition to occur. Such a change does not occur in poly(acrylic acid) on the one hand and methyl vinyl ether/maleic anhydride copolymer on the other. The nature of the transition is discussed in terms of the freedom of rotation of the side chains about the main chain.
UV‐photometrisch bestimmte relative molare massen von anionisch erzeugten polyäthylenoxiden mit unterschiedlichen endgruppen
Authors: Kämmerer Hermann , Grover Pran Nath 
Published: April 2003

AbstractÄthylenoxid wurde mit Kalium‐4‐(phenylazo)benzylalkoholat (1f) polymerisiert, die gereinigten Produkte fraktioniert und anschließend acyliert. Die UV‐photometrische Bestimmung der Endgruppen ergab, daß HO‐Endgruppen, verglichen mit den Starterendgruppen, in großem Überschuß vorhanden waren. Aus den Endgruppenwerten ließen sich Zahlenmittel des Molekulargewichts (M̄n) ableiten. Sie wurden mit osmotisch bestimmten M̄n‐Werten und Viskositätsmittel (M̄η)‐verglichen und bestätigten die angenommene Struktur der Polyäthylenoxide.
Kinetic investigations on biosynthesis of bacterial cellulose, 2. Distribution of the degree of polymerization for different numbers of bacterial generations
Authors: Marx‐Figini Marianne , Pion Beatriz 
Published: April 2003

AbstractThe chain length distribution of polymer analogous nitrates of two native bacterial celluloses is investigated. The polymerization times of the latter differend in the numbers of generation of the bacteria produced during the fermentation of acetobacter xylinium. The resulting distribution curves show that polydispersity and number of maxima increase with increasing number of generation. This result supports the hypothesis deduced from former kinetic investigations that each generation of bacteria initiates a certain number of molecules and that chain growth takes place without termination step.
Zur deutung der sogenannten a‐orientierung in polyäthylenterephthalat
Authors: Biangardi Harald J. , Zachmann H. Gerhard 
Published: April 2003

AbstractBei der Kristallisation von schwach orientierten Polyäthylenterephthalat‐Folien erhält man eine Struktur, für die in der Röntgenweitwinkelstreuung der 100‐Reflex am Meridian und der 010‐Reflex am Äquator liegt. Die Röntgenkleinwinkelstreuung zeigt ein Intensitätsmaximum am Meridian.Man kann diese Befunde mit einem Modell aus tordierten Lamellen erklären, deren Torsionsachsen bevorzugt senkrecht zur Verstreckrichtung liegen. In einer solchen tordierten Lamelle liegen die (001)‐Ebenen der Kristallite parallel zur Lamellenoberfläche und die b‐Achsen in Richtung der Torsionsachse. Die bei dieser Struktur auftretende negative Doppelbrechung kann mit diesem Modell ebenfalls erklärt werden.
Effects of salts, solvents, and substituents on the reaction of cellulose with epoxy compounds
Authors: Tanaka Yoshio , Shimura Yukio , Shiozaki Hideki 
Published: April 2003

AbstractEffects of salts, solvents, and substituents on the reaction of cellulose with epoxy compounds were re‐investigated and compared with the published data. The salt effect could be described mainly by the electronegativity or the acidity of the cations, and also by the nucleophilicity or the basicity of the anions. The variation of the reaction with solvents for epoxy compounds could be explained by the solubility parameter of the solvents. The substituent effect of the epoxy compounds on this addition reaction was elucidated by the modified Taft's equation, (logk−logk0)/σ*=(Qp–QsEs)/σ*. The mechanism for the reaction was discussed in the light of the reinvestigated phenomena.
Über polymere Alloxazine, 2
Authors: Manecke Georg , Reuter Peter 
Published: April 2003

Abstract7‐Vinylalloxazin (4) wurde auf einem neuen Weg dargestellt. Es konnte weder in DMSO noch in DMF polymerisiert werden. Poly(7‐vinylalloxazin) (7) wurde durch polymeranaloge Reaktionen von Poly(4‐aminostyrol) ausgehend dargestellt; seine Eigenschaften bei der Komplexierung mit Ag+‐ und Hg2+‐Ionen wurden untersucht.