bluuebunny/crossref_metadata_2025_split huggingface dataset:
Der aufbau einiger homologer reihen von hydroxyphenylenmethylen‐verbindungen und ihr schmelzverhalten
Authors: Kämmerer Hermann , Niemann Wilhelm 
Published: April 2003

AbstractWill man das Schmelzverhalten von Novolaken voraussagen, dann ist es notwendig, die Eigenschaften der Hydroxyphenylenmethylen‐Verbindungen, früher als phenolische Mehrkernverbindungen bezeichnet, zu kennen, welche im Novolak enthalten sind. Daher wurden zur Ermittlung von Struktur/Eigenschaft‐Beziehungen einige homologe Reihen von Hydroxyphenylenmethylen‐Verbindungen hergestellt und ihr Schmelzverhalten untersucht. Dabei stellte sich heraus, daß das Schmelzverhalten der Hydroxyphenylenmethylen‐Verbindungen, das von Endgruppen und vermutlich konformativen Faktoren beeinflußt wird, verwickelt und weitgehend ungeklärt ist. Der Aufbau der streng homologen Hydroxyphenylenmethylen‐Verbindungen (3. Reihe) erfolgte auf zwei verschiedenen Synthesewegen. Außer Elementaranalyse und Molekulargewichtsbestimmung dienten zur Charakterisierung der neu hergestellten Verbindungen die Derivate, die durch vollständige Acetylierung aller phenolischen Hydroxylgruppen im Molekül erhalten wurden.
On the absence of stereoselectivity in the stereospecific polymerization of racemic 5‐methyl‐1‐heptene and 2‐methylbutyl vinyl ether
Authors: Chiellini Emo , Marchetti Massimo 
Published: April 2003

AbstractStereoregular polymers of racemic 5‐methyl‐1‐heptene (I) and 2‐methylbutyl vinyl ether (II), obtained by isospecific polymerization, when supported on poly[(S)‐3‐methyl‐1‐pentene](poly[sec‐butylethylene]) and on poly(L‐dilactide)(poly[L‐oxyethylidencarbonyl]) respectively give, by elution with solvents, optically inactive fractions.On the contrary, optically inactive mixtures of equimolar amounts of stereoregular poly‐[(S)‐] and poly[(R)‐5‐methyl‐1‐heptene] (poly[(3‐methylpentyl)‐ethylene]) as well as of poly[(S)‐] and poly[(R)‐2‐methylbutyl vinyl ether] (poly[(2‐methylbutoxy)ethylene]), can be separated under the same experimental conditions into fractions having optical activity of opposite sign.Even if the efficiency of the last separation is not very high (∼20%), the obtained results indicate that the polymeric products from racemic 5‐methyl‐1‐heptene and 2‐methylbutyl vinyl ether can be considered as random copolymers of the two enantiomers.The comparable cristallinity of polymers from the above racemic monomers and from the corresponding optically active ones must be attributed to an indistinguishable arrangement of R and S monomeric units in the crystalline lattice.
Syntheses and reactions of functional polymers, 74. Syntheses of poly[1‐methyl‐1‐(5‐oxo‐4,5‐dihydro‐1,3,4‐oxadiazol‐2‐yl)‐ethylenes]
Authors: Endo Takeshi , Inoue Takeshi , Okawara Makoto 
Published: April 2003

Abstract2‐Isopropenyl‐5‐oxo‐4,5‐dihydro‐1,3,4‐oxadiazoles (II) were prepared by the reaction methacrylohydrazides (I) with phosgene and their abilities for polymerization and copolymerization were investigated. The monomer reactivity ratios were determined in bulk polymerization. The polymers obtained were soluble in dimethylformamide and dimethylsulfoxide, but insoluble in common organic solvents. Some properties of these polymers were examined.
Polychalkone, IV. Gaschromatographisch‐pyrolytische untersuchungen wärmebeständiger polychalkone
Authors: Caşcaval C. N. , Oleinek Heinz , Zugrăvescu Ion , Schneider I. A. 
Published: April 2003

AbstractIn der vorliegenden Arbeit werden aus gaschromatographisch‐pyrolytischen Untersuchungsergebnissen einige Aussagen über die Wärmebeständigkeit und Struktur von Polychalkonen abgeleitet. Es zeigt sich, daß die Abschwächung der Elektronenwechselwirkung durch Unterbrechung der Konjugation des π‐Elektronensystems in der Hauptkette der Makromoleküle sich in den erhaltenen Chromatogrammen widerspiegelt.
Untersuchungen zum oxidativen abbau nativer cellulose. I. Das anfangsstadium des heterogenen abbaus von alkalicellulose aus baumwolle und eine beziehung zur struktur der elementarfibrillen
Authors: Palma A. , Jovanović S. , Schulz G. V. 
Published: April 2003

AbstractBehandlung nativer Baumwollcellulose mit NaOH verschiedener Konzentration über längere Zeiten unter Reinstickstoff vermindert den STAUDINGER‐Index der Cellulose in CUOXAM und des daraus hergestellten Cellulosetrinitrats (CTN) in Aceton um einen erheblichen Betrag. Lichtstreuungsmessungen zeigen, daß während dieses Prozesses das Molekulargewicht erhalten bleibt, während der Trägheitsradius abnimmt und der 2. Virialkoeffizient zunimmt. Die enge Molekulargewichtsverteilung des nativen Produkts bleibt hierbei erhalten. Schwache Sauerstoffzufuhr erhöht zunächst die Viskosität, um sie erst bei längerem Abbau zu erniedrigen.Diese Phänomene werden folgendermaßen gedeutet : Die Cellulosemoleküle liegen in den Elementarfibrillen in gefalteter Form vor. Während der Alkalibehandlung entstehen chemisch resistente intramolekulare Vernetzungsstellen, so daß aus der linearen Cellulosekette ein mehrfach cyklisiertes Molekül erhalten wird. Die oxidative Aufspaltung der Ringe erhöht zunächst den Trägheitsradius (in Lösung), während das Molekulargewicht noch erhalten bleibt.
Twinning in polyacrylonitrile
Authors: Gohil R. M. , Patel K. C. , Patel R. D. 
Published: April 2003

AbstractA great variety of twinned crystals of polyacrylonitrile (PAN) are grown by Film Formation Method. They have been classified according to their origin. It has been shown that twins of polymer crystals originate by several mechanisms. Habit and orientation of secondary lamellae generated by various mechanisms on twinned crystals have been studied.
Studies on metal chelating polymers, 2. Preparations and properties of cationic polymers containing the 3‐acetyl‐4‐hydroxybenzyl group in the side chain
Authors: Haruta Masami , Kageno Kenji , Harada Susumu 
Published: April 2003

AbstractDiallyl(3‐acetyl‐4‐hydroxybenzyl) methylammonium chloride (I) was prepared. The copolymerization of I with sulfur dioxide, and the terpolymerizations of I with other diallyl compounds and sulfur dioxide were carried out under various conditions. The effect of the polymerization conditions on the yields and the viscosities of the obtained polymers was studied.IR‐spectra, solubilities, and thermal stabilities of the polymers were examined. An apparent dissociation constant for the phenolic proton in the product of terpolymerization of I with diallyldimethylammonium chloride and SO2 was determined by the spectral method.
Polymerization of methacrylaldehyde and crotonaldehyde started by various initiators of anion‐radical type
Authors: Rashkov Ilya B. , Spassov Stephan L. , Panayotov Ivan M. 
Published: April 2003

AbstractThe polymerization of methacrylaldehyde (methacrolein; MAC) and crotonaldehyde (CA) initiated by the anion‐radical type initiators potassium diphenylketyl, potassium dihydronaphthylide and the potassium‐graphite inclusion compounds C8K, C16K, C24, and C32K was investigated with the intention to find polymerization conditions under which side reactions with aldehyde groups in the polymer do not proceed to a considerable degree. The structures of polymethacrylaldehyde (PMAC) and polycrotonaldehyde were determined by IR and NMR spectroscopy. It was established that PMAC has a high content of tetrahydropyran rings. With the aid of quantum chemical methods it was shown that the formation of complexes between the propagating polymer end and the monomer molecule is energetically advantageous and leads to the formation of tetrahydropyran rings in the propagation reaction of MAC.
Über chelat‐bildung monomerer und polymerer derivate des 3‐vinyl‐benz[f]indazol‐4,9‐dions
Authors: Manecke Georg , Graudenz Eckhard 
Published: April 2003

Abstract5,8‐Dihydroxy‐3‐vinyl‐1H‐benz[f]indazol‐4,9‐dion (Ia), sein 1‐Methylderivat I d und sein 2‐Methylderivat II bilden mit den zweiwertigen Kationen Mg2+, Cd2+, Ni2+, Zn2+ und Cu2+ polymere 1:1‐Chelate abgestufter Stabilität. Das 5‐Hydroxyderivat Ib bildet 2:1‐Chelate, deren Stabilität in gleicher Weise abgestuft ist. Der Pyrazolwasserstoff reagiert mit Zn2+‐lonen zu schwerlöslichen basischen Salzen.Die mit 3,7‐Divinyl‐pyrazolo[5,4‐f]indazol‐4,8‐d on (VIIa) vernetzten Harze nehmen in der Alkaliform rasch zweiwertige Kationen aus gepufferten Lösungen auf, wobei eine starke Spezifität für Cd2+ und Cu2+‐Ionen festgestellt wird. Trennversuche an den Harzen in einer Säule ergaben scharfe Trennungen für das Gemisch Cu2+/Ni2+.Die Möglichkeit, das Monomere auf der Oberfläche von Kieselgel zu polymerisieren, weist einen Weg zur Verbesserung der Harzeigenschaften.
Mathematical properties of polydisperse systems, 2. Application to light scattering
Authors: Greschner Georg S. 
Published: April 2003

AbstractThe direct and the inverse problem of the light scattering from dilute polymer solutions is solved for GAUssian coils at the theta point. Theoretical scattering functions and their derivatives are analytically calculated for the general gamma distribution of molecular weights as a function of the non‐uniformity and the weight average molecular weight, and also for various ratios of the statistical segment length of the coil to the wave length of the scattered light. The asymptote and the tangent of P are obtained by analysing the operator in the ZIMM equation and their mutual position is compared in the angle range 150° to 180°. The scattering envelopes of microgel systems are analytically calculated and discussed. In order to obtain the molecular weight distribution (MWD) from a given ZIMM diagram of GAUssian coils at the theta point, the corresponding inverse problem is solved analytically, the necessary zero approximation of the segment length being taken from viscometric measurements. With the help of the presented method the MWD and the correct statistical segment length of the coil can theoretically be computed with any reasonable accuracy. However, the calculation shows that for practical use extremely high accuracy of the light scattering measurements is necessary.
Copolymères séquencés de l'époxyéthane avec les épithioalcanes
Authors: Boileau Sylvie , Sigwalt Pierre 
Published: April 2003

AbstractNous avons étudié la réaction de quelques épithioalcanes avec des solutions de poly(oxy‐éthylène) «vivant» prepare anioniquement en utilisant le carbazolyl‐9 potassium comme agent d'amorçage. Il est possible de préparer avec de bons rendements des copolyrméres séquencés de type AB où A représente une séquence de poly(oxyéthylène) et B correspond à une séquence de poly(thioéthylène) ou poly(thio‐diméthyl‐1,1‐éthylène). Par contre, des réactions de transfert interviennent entre les extrémités alcoolate du poly(oxyéthylène) et l'épithio‐1,2‐propane et l'on n'obtient pas de copolymère séquencé dans ce cas.
Use of Zn(C2H5)2 in olefin polymerization catalytic system, 1. Reaction of Zn(C2H5)2 with γ‐TiCl3 and study of the catalyst
Authors: Guyot Alain , Sili Pierre , Agouri Elias , Laputte Robert 
Published: April 2003

AbstractThe gaseous and solid products of the reaction of Zn(C2H5)2 dissolved in heptane with TiCl3 in the presence of Al(C2H5)3 are studied for various conditions using gas liquid chromatography, X‐ray diffraction, BET surface area measurements and chemical analysis.It is shown that, besides the common surface alkylation and reduction one may observe for higher temperatures and higher Al/Ti catalyst ratios a decomposition of Zn(C2H5)2 at the same time as the cristalline organisation of TiCl3 disappears. The products are mostly metallic zinc, hydrogen, ethane, butane and 1‐butene which is subsequently isomerized or polymerized.
Über das 3,4‐diaminostyrol, 2
Authors: Manecke Georg , Rotter Ulrich 
Published: April 2003

AbstractNeben einer weiteren Synthese für 4‐Amino‐3‐nitrostyrol wird über die Darstellung und die Eigenschaften einiger C‐Vinylbenzopyrazine berichtet, welche durch Kondensation von 3,4‐Diaminostyrol mit o‐Diketonen erhalten werden. Das 2,3‐Diphenyl‐6‐vinylchinoxalin wird in Lösung polymerisiert sowie mit Styrol und divinylbenzol copolymerisiert.
Polymerization of acrylonitrile with diethyl magnesium
Authors: Dimonie Victoria 
Published: April 2003

AbstractThe polymerization of acrylonitrile, initiated by diethyl magnesium in toluene at low temperatures, was investigated. Some particularities of this process, such as rapid initiation, termination of chain growth, interaction between catalyst and aromatic hydrocarbon medium leading to the formation of active centers, are emphasized. It was found that a temperature increase considerably increases the termination processes. Based on these findings and on the dependence of the polymer yield on monomer and catalyst concentrations, a kinetic scheme of the polymerization process is suggested.
A rotating sector determination of the propagation rate constant for benzyl methacrylate in its radical polymerization
Authors: Yokota Kenji , Kondo Akimasa 
Published: April 2003

AbstractThe unusually large propagation rate constant for benzyl methacrylate reported in the previous paper was studied in more detail. The decomposition rate of 2,2′‐azoisobutyronitrile in this viscous monomer was somewhat smaller than in ordinary solvents. A regular monomer kinetic order could be realized in butanol and in benzyl butyrate whose viscosities were very similar to that of the monomer. A rotating sector experiment in benzyl butyrate gave kp = 1410 dm3 mol−1 s−1 for this monomer, which was essentially identical with the previous result.
Phase diagram and structural study of polystyrene — poly(ethylene oxide) block copolymers, 1. Systems polystyrene/poly(ethylene oxide)/diethyl phthalate
Authors: Gervais Monique , Gallot Bernard 
Published: April 2003

AbstractBy means of low angle X‐ray scattering and differential scanning calorimetry, we have drawn the phase diagrams of poly(ethylene oxide)‐polystyrene block copolymers in the presence of diethyl phthalate as a preferential solvent of polystyrene.Such systems exhibit two liquid‐cristalline structures in terms of temperature and solvent concentration. At temperatures below about 50°C, a lamellar structure (LC) with crystallized poly(ethylene oxide) chains exists. Between 50 and about 170°C, we find a structure with melted poly(ethylene oxide) chains. Like for amorphous block copolymers, the type of the latter structure is governed by the copolymer composition.We have shown that in the LC structure, the poly(ethylene oxide) chains crystallize folding in two superposed layers, and we have studied the number of folds and the crystallinity of the poly(ethylene oxide) blocks as a function of solvent concentration, composition and rel. mol. mass of the copolymer, and of the crystallization temperature.
Temperaturabhängigkeit des quellungsgleichgewichtes bei peroxidvernetzten polymerproben
Authors: Butenuth Gottfried , Wolff Siegfried , Stegmaier Herbert 
Published: April 2003

AbstractDie Quellungsgrade peroxidvernetzter Polymerproben aus Naturkautschuk, Butadien‐Styrol‐Copolymerem und cis‐Polybutadien wurden bis herunter zu einer charakteristischen Temperatur TK experimentell bestimmt. Der Wechselwirkungs‐Parameter χ erreicht bei TK, unabhängig von der Vernetzungsdichte der Proben, den Wert ao = 0,5. Eine Methode zur Bestimmung von Vernetzungsdichten auf dieser Grundlage wird vorgeschlagen.
Polymerization of aromatic aldehydes, 9. Cationic copolymerization of furfural and vinyl ethers
Authors: Kunitake Toyoki , Yamaguchi Katsuhiko , Aso Chuji 
Published: April 2003

AbstractCationic copolymerizations of furfural were carried out with several vinyl monomers. No copolymers were obtained with some hydrocarbon comonomers. At low temperatures furfural copolymerized with vinyl ethers selectively through the aldehyde group. On the other hand, deeply‐colored copolymers of complex structures were formed at higher temperatures (ca. 0°C). Three typical vinyl ethers (p‐tolyl vinyl ether, dihydropyran, and divinyl ether) were selected as comonomers, and their copolymerization behaviour studied in detail. The monomer reactivity ratios for furfural (M1) and p‐tolyl vinyl ether (M2) were r1 = 0,15 ± 0,15, r2 = 0,25 ± 0,05. The furfural (FF) contents were fairly independent of the monomer feeds when dihydropyran (DHP) and divinyl ether (DVE) were used as comonomers: 37–47% for FF‐DHP copolymers and 40–50% for FF‐DVE copolymers. More than half of the second vinyl groups were consumed in the FF‐DVE copolymers indicating the formation of 1,3‐dioxane rings as in the case of benzaldehyde‐DVE copolymers.
Determination of stability constants of complex formation of poly(N‐vinylcarbazole) and N‐ethylcarbazole with electron acceptors
Authors: Boudevska Hrisanta , Velinov Georgi , Tchobanova Ivanka 
Published: April 2003

AbstractThe complex formation in chloroform solution of poly(N‐vinylcarbazole) and N‐ethylcarbazole with the electron acceptors tetracyanoethylene, tetrachloro‐p‐benzoquinone (chloranil) and 1,3,5‐trinitrobenzene was studied. The stability of the donor‐acceptor complexes with mole ratios of 1:1 was determined spectrophotometrically by a modified method of successive dilution.A mathematical method was developed for a simultaneous determination of the extinction coefficient and of the stability constant by conversion of a quadratic relation into a linear form and by application of the least square method. The experimental results were treated by a computer program.The values obtained by this method for the extinction coefficients and for the stability constants of N‐ethyl carbazole complexes are higher than those of poly(N‐vinylcarbazole) complexes. The change of the electron affinity of the acceptors does not affect considerably the stability constants of the complexes.
Reduction of poly(vinyl ketone)s into secondary poly(allyl alcohol)s
Authors: Merle‐Aubry Liliane , Merle Yves , Selegny Eric 
Published: April 2003

AbstractDifferent poly(vinyl ketone)s
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in which R is an alkyl or phenyl radical were reduced by lithium aluminum hydride or by potassium tetrahydroborate.The influences of the substituent R, of the nature and quantity of the hydride, and of the duration of the reaction on the degree of reduction are described. Amine derivatives of the polyalcohols are prepared.
Über eine beziehung zwischen verdünnungsentropie und verdünnungsenthalpie in lösungen von polystyrol und polymethylmethacrylat
Authors: Lechner M. D. , Schulz G. V. 
Published: April 2003

AbstractDurch Lichtstreuungsmessungen wurde der Entropieanteil und der Enthalpieanteil des 2. osmotischen Virialkoeffizienten (A2) von athermischen und exothermischen Lösungen von Polystyrol (PS) und Polymethylmethacrylat (PMMA) bei 25°C und Normaldruck bestimmt. Zur Auffindung von athermischen und exothermischen Lösungsmitteln für diese Polymeren wurde die Temperaturabhängigkeit des STAUDINGERindex verwendet. Die ermittelten thermodynamischen Größen A2, A2,S und A2,H ergeben zusammen mit früheren Messungen eine beziehung, die nahezu unabhängig vom speziellen System ist.
Comportement de polystyrènes ramifiés en étoile et en peigne dans quelques mélanges de solvants. Influence du degré de ramification sur l'adsorption préférentielle
Authors: Hert Marius , Strazielle Claude , Benoit Henri 
Published: April 2003

AbstractLe coefficient d'adsorption préférentielle en solution diluée d'un polymère en mélange de solvants, est une fonction de la densité moyenne en segments intramoléculaire. Cet effet, déjà mis en évidence pour des polystyrènes linéaires en solvants binaires, a été observé pour des polystyrènes ramifiés à structure en étoile et en peigne, pouvant atteindre des densités locales importantes, dans le mélange benzène/méthanol. Une relation du type:

(<v3> étant la fraction en volume moyenne intramoléculaire du polymère), établie à partir des théories thermodynamiques de l'équilibre de solvatation, permet de rendre compte des résultats expérimentaux.Une étude comparative des coefficients d'adsorption de polystyrènes ramifiés et des polystyrènes linéaires de měme masse moléculaire, a permis dans certains cas particuliers, de déterminer le paramètre de structure g du polystyrène ramifié.
Operating conditions for successive precipitational fractionation of macromolecules, 2. Analytical fractionation
Authors: Kamide Kenji , Miyazaki Yukio , Yamaguchi Keiko 
Published: April 2003

AbstractOperating conditions, including the initial concentration, the total number of fractions, n, and some refractionation procedures, in the successive precipitational fractionation (SPF) are investigated as well as the reverse‐order fractionation phenomena in the case of analytical fractionation. SPF is ineffective for determining of the molecular weight distribution of the original polymer if its polydispersity is very small. The SCHULZ plot, obtained from the data for the total number of fractions, n = 4, is practically indistinguishable from the corresponding plot for n = 20 to 30. In contrast to this, the KAMIDE plot approaches the true distribution with increasing n. The breadth in the molecular weight distributions remains effectively constant for n ≥ 10, compared with the same weight‐average molecular weight. The reverse‐order fractionation hardly occurs, from the theoretical point of view, provided that the polymer‐rich and polymer‐lean phases are in thermodynamic equilibrium. The ratio of the weight‐ to number‐average degree of polymerization, X̄w/X̄n, in the fractions obtained by refractionation procedures does not approach an asymptotic value even if the refractionation is repeated five times. The refractionation with the fraction size, ρ = 1/2 is found to be very effective. For a given pair of polymer and a solvent, the minimum value of X̄w/X̄n attainable from a solution of a given initial concentration, by SPF, can be calculated by a computer simulation technique.
Model calculation of the gas diffusion through the polymer bulk
Authors: Jagodic Franc , Borštnik Branko , Ažman Andrej 
Published: April 2003

AbstractA model calculation of the diffusion of a noble gas (Ar) through the polyethylene bulk is performed on the molecular scale. The amorphous phase of the polymer chains is generated by computer calculation and the potential field due to the penetrating atom is evaluated. The diffusion process across the barriers is simulated to obtain the value of the diffusion constant.
An apparent cocatalytic effect of hydrogen fluoride during the polymerization of isobutene with lewis acids
Authors: Lopour Peter , Pecka Jan , Marek Miroslav 
Published: April 2003

AbstractThe effect of hydrogen fluoride on the polymerization of isobutene in heptane catalyzed with various FRIEDEL‐CRAFTS halides (TiCl4, TiBr4, TiJ4, VCl4, WCl6, PCl5, BCl3, SnCl4, SiCl4, GeCl4, and AsCl3) was investigated. It was found that hydrogen fluoride and the first eight halides form catalytic systems which are effective initiators of the polymerization of isobutene. From the experimental results it follows, that the catalytically active compounds are products arising from an exchange of the halogen atom between the individual FRIEDEL‐CRAFTS halides and hydrogen fluoride.
Statistische thermodynamik von lösungen unter berücksichtigung der verhakung von makromolekülen
Authors: Hoffmann Martin 
Published: April 2003

AbstractUnter der Annahme, daß große Moleküle eines amorphen Polymeren in der unverdünnten Schmelze und ebenso bei der Polymerkonzentration φ Verhakungsnetzwerke mit athermischen Konformationen bilden, kann man eine Entropiedifferenz Sφ—Sφ = 1 berechnen, die daher rührt, daß das Molekulargewicht Mc der Netzbögen nach BUECHE von der Konzentration abhängt. Benutzt man dazu die bekannten Gleichungen für die Entropie von Hauptvalenznetzwerken und führt Sφ—Sφ = 1 in die bekannten Formeln für die freie Mischungsenthalpie ein, so erhält man die experimentell gefundenen und bisher nicht verstandenen Gesetze und Konstanten der Konzentrationsabhängigkeiten von osmotischem Druck, Lichtstreuintensität und Diffusionsgeschwindigkeit großer Moleküle bei mittleren Konzentrationen. Man erkennt ferner, daß die maximale Quellung vernetzter Polymerer den Quotienten der Anzahl an Verhakungen zu der Anzahl Vernetzungen liefert.