bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Behandlung 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

A 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

Diallyl(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

The 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

5,8‐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

The 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

Nous 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

The 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

Neben 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

The 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

The 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

By 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

Die 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

Cationic 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

The 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

Different poly(vinyl ketone)s
magnified image
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

Durch 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

Le 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:

( 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

Operating 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

A 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

The 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

Unter 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.
Transesterification of poly(methyl acrylate) with optically active alcohols
Authors: Yamaguchi Hidemasa , Fujiwara Yoshiaki , Minoura Yuji
Published: April 2003

Transesterifications of atactic and isotactic poly(methyl acrylate) with optically active alcohols such as (S)‐2‐methyl‐butanol, D‐borneol and L‐menthol were carried out in toluene at 100°C using p‐toluenesulfonic acid as catalyst to obtain optically active polymers. In addition a relationship between the conformation and the optical behaviour of the transesterified poly(methyl acrylate) was investigated. The specific rotation of the transesterified atactic poly(methyl acrylate) increased linearly with increasing introduced optically active groups at the lateral chain, in contrast to that of the isotactic poly(methyl acrylate) which increased nonlinearly with increasing introduced asymmetric groups. Since the specific rotations of the transesterified polymers depend on these tacticities the conclusion was drawn that the optical activity is caused not only by the asymmetric group in the lateral chain but also by molecular dissymmetry in the principal chain.
Poly(2‐vinylquinoline 1‐oxide) and some methyl derivatives: Synthesis and viscometric studies
Authors: Bonsall Colin , Holt Paul
Published: April 2003

The syntheses of poly[1‐(1‐oxy‐2‐quinolyl)ethylene] [poly(2‐vinylquinoline 1‐oxide)] (1a) and of a number of methyl derivatives (1b—f) are described. Some of the polymers are insoluble in water but soluble in aqueous acetone at several pH values. Those polymers that have a methyl substituent in position 4 are soluble in aqueous acetone below pH < 4 and the viscosity rises steeply with decreasing pH. Polymers with no methyl substituent in position 4 are soluble in aqueous acetone at pH > 6 and the viscosity varies but little with the pH.
On the properties and thermal conversion of ladder polymers with conjugated bonds
Authors: Salaurov V. N. , Kryazhev Yu. G. , Yushmanova T. I. , Vakul'Skaya T. I. , Voronkov M. G.
Published: April 2003

The cationic polymerization of vinylacetylenes can be implemented using an excess of catalysts, such as BF3O(C2H5)2, SnCl4, H2SO4, CCl3COOH, CF3COOH (20–50 mol per 100 mol monomer). This is due to the formation of a charge‐transfer complex between the catalyst and the polymer obtained, which was confirmed by UV, ESR and IR spectra.

Polymers with conjugated ladder sequences in the chain (LP) (4) were prepared using vinylacetylene (1a), 1‐hexen‐3‐yne (1b), 2‐methyl‐1,5‐hexadiene‐3‐yne (3a), 2‐methyl‐5‐hexen‐3‐yn‐2‐ol (3b) or 5‐methoxy‐5‐methyl‐1‐hexen‐3‐yne (3c). The polymers obtained (molar mass = 2000–7000) are pale yellow to pale brown powders which display properties characteristic of polymers with conjugated bonds, i.e. thermal stability in vacuum and air, continuous absorption in UV and near visible regions, broad fluorescence spectra, electric conductivity and ESR signals.

The effect of heat treatment in vacuum and air on the structure and some electrophysical properties of LPs was studied by IR, luminescence, ESR and mass‐spectroscopy and also by TGA, DTA, and X‐ray diffraction analyses.

The heat treatment in the temperature range of 150–400°C gives rise to a complete cyclization accompanied by a partial degradation and leads to the formation of polycondensed aromatic structures and to a sharp increase of electroconductivity up to 1.10−5Ω−1cm−1 and to an increase of the concentration of paramagnetic particles up to 1.1020 spin/g at an ESR signal width in vacuum of 0,4 gauss (0,4.10−4 tesla).
Polyélectrolytes optiquement actifs à hydrophobie variable, 1. Copolymères amide‐acide acryliques obtenus par hydrolyse contrǒlée des (±), (+) et (−) poly[N‐(sec‐butyl)‐N‐méthyl‐acrylamides]
Authors: Braud Christian , Vert Michel , Sélégny Eric
Published: April 2003

On hydrolyse progressivement en milieu acide (CH3COOH + HCl) les (±), (+) et (−) poly‐[N‐(sec‐butyl)‐N‐méthylacrylamide] (1) obtenus par polymérisation radicalaire des (±), (−) et (+) N‐(sec‐butyl)‐N‐méthylacrylamides (AAM). On obtient une série de copolymeères (2) consititués de motifs hydrophobes dérivés de AAM et de motifs hydrophiles dérivés de l'acide acrylique (AA) répartis statistiquement et en proportion variable selon le temps d'hydrolyse. La viscosité, le pouvoir rotatoire dans le méthanol, la solubilité dans divers solvants, les spectres IR à l'état solide et la dispersion de la rotation optique (ORD) sont étudiés en fonction du taux d'hydrolyse. Pour interpréter l'évolution de l'ORD et des spectres IR on a supprimé les interactions H entre groupes amide et acide par méthylation de ces derniers au diazométhane. Au cours de la neutralisation des différents copolymères 2 par KOH, on constate que l'augmentation de la proportion des parties hydrophobes par rapport aux parties hydrophiles modifie fortement l'ionisation des groupes COOH des motifs monomères dérivés de l'acide acrylique.
Solution properties and unperturbed dimensions of poly(5‐p‐methyl methacrylate) and poly(2‐tert‐butylphenyl methacrylate)
Authors: Tricot Michel , Bleus Joseph P. , Riga Jean‐Pierre , Desreux Victor
Published: April 2003

The solution properties of poly(5‐p‐menthyl methacrylate) and poly(2‐tert‐butylphenyl methacrylate) are determined by several methods in good and ideal solvents. The flexibilities σ calculated on the basis of the unperturbed dimensions are 3,1 and 2,6, resp. These values are compared with those found for other polymethacrylates with bulky substituents. The influence of a large group in ortho position at the cyclohexyl and the phenyl rings is discussed in terms of steric hindrance and specific interactions.
Crystallinity and polymorphism of 6‐polyamide
Authors: Gurato Giorgio , Fichera Annamaria , Grandi Francesco Zilio , Zannetti Roberto , Canal Pietro
Published: April 2003

By X‐ray diffraction and by density measurements as well as by differential scanning calorimetry, the crystallization phenomena of 6‐polyamide(nylon‐6) samples, obtained under different conditions were investigated.

Particularly we have analyzed a method for the quantitative determination of the α, γ, and δ (amorphous) phases. This was based on the decomposition of the areas of the X‐ray diffraction patterns. These data were related with density and calorimetric measurements and finally gave a good picture of the transitions involving the different phases.

We have used this method for the characterization of nylon‐6 of low and medium viscosity and we have considered the differences of behaviour between the various series of samples.
Detection of tie‐molecules by thermal analysis
Authors: Mehta Aspy , Wunderlich Bernhard
Published: April 2003

New experiments are presented which demonstrate the presence of tie‐molecules in bulk‐crystallized linear polyethylene. The experiments involve analysis by differential scanning calorimetry (DSC) on originally crystallized samples and undissolved residues left behind after partial extraction of these samples.
Approaches towards a comprehensive theory of the cationic polymerisation of olefins
Authors: Plesch Peter H.
Published: April 2003

Some of the factors which influence, or must be contained in, a Comprehensive Theory of the cationic polymerisation of olefins are discussed from new points of view, starting from the author's new theory concerning initiation by metal halides. Alleged determinations of the rate constant k are criticised because they ignored two equilibria which make the concentration of growing polymer chains [P] in general less than the nominal concentration, c0, of initiator. One of them is a binary ionogenic equilibrium involving metal halide MtXn and polymer halide PnX. The other is between metal halide and olefin. An equation relating [P] to c0 is deduced which takes account of these equilibria. The importance of the second equilibrium is illustrated by the way in which it provides simple explanations of hitherto obscure phenomena. Some of these arise during the interaction of aluminium halides with olefins in different circumstances, others concern the different interactions which can take place between titanium tetrachloride and 1,1‐diphenylethylene. The fact that titanium tetrachloride appears to be able to initiate without co‐initiator in some systems, but requires one in others is explained by the self‐ionisation of the metal halide and the effects of impurities.
Über polymere mit phenyltropylium‐ und styryltropyliumsalzgruppierungen
Authors: Manecke Georg , Steudle Ernst
Published: April 2003

Anionaustauscherharze mit der Tropyliumgruppe wurden dargestellt. Poly{1‐[4‐(1,3,5‐cycloheptatrien‐7‐yl)phenyl]äthylen} (3) wurde durch thermische Polymerisation von 7‐(p‐Vinylphenyl)‐1,3,5‐cycloheptatrien (2) erhalten. Das schwach gelbgrün gefärbte, lösliche Polymere 3 (rel. mol. Masse=4330) wurde durch sein IR‐Spektrum charakterisiert. Die Dehydrierung von 3 lieferte ein Poly[1‐(4‐tropyliumylphenyl)äthylenperchlorat] (4) in dem 78% der 1,3,5‐Cycloheptatrien‐Reste dehydriert waren. Das polymere Tropyliumsalz 4 tauschte beim alternierenden Behandeln mit 0,1 N NaOH und 25proz. Perchlorsäure reversibel 2,0–2,5 mVal/g Perchlorationen gegen Hydroxylionen aus. Bei der Kondensation von Poly[1‐(4‐formylphenyl)äthylen] (5) mit Methyltropyliumperchlorat (6) wurden schwarze Polymere mit 1‐[4‐(2‐Tropyliumylvinyl)phenyl]äthylen‐Gruppierungen (7) erhalten, die unter den obigen Bedingungen reversibel 1,0–1,5 mVal/g austauschten.

Die polymeren Tropyliumsalze 4 und 7 wurden durch ihre IR‐Spektren charakterisiert.
Modell‐untersuchungen zur struktur eines polyimids aus pyromellithsäuredianhydrid und benzidin
Authors: Brune Hans‐Albert , Horvath Andreas , Vollmert Bruno
Published: April 2003

Anhand geeigneter Modellverbindungen konnte 1H‐NMR‐spektroskopisch nachgewiesen werden, daß sich auch am isolierten, gelösten Molekül des N‐Phenylphthalimids eine zeitlich stationäre sp2‐Hybridisierung mit ebener Anordnung der drei vom Stickstoff ausgehenden σ‐Bindungen einstellt. Diese Bindungsverhältnisse haben für das Polyimid der Pyromellithsäure, Poly(pyromellithdiimido‐4,4′‐biphenylylen) (4), eine streng lineare, stäbchenförmige Struktur des Makromoleküls zur Folge.
Cationic polymerization of cyclic sulfides, 5 Polymerization of propylene sulfide with triethyloxonium tetrafluoroborate
Authors: Van Ooteghem Daniël R. , Goethals Eric J.
Published: April 2003

Time‐conversion curves show that the polymerization of propylene sulfide (1) by triethyloxonium tetrafluoroborate (TEFB) in methylene chloride consists of an initial very fast, non‐stationary stage A and a much slower subsequent stage B which leads to quantitative conversion. The termination reaction of stage A is of first order with respect to initiator concentration and is independent of monomer concentration. The proposed mechanism for this termination is the formation of a (mainly) 12‐membered cyclic sulfonium salt at the end of the polymer chain. The ratio of the rate constant of propagation to the rate constant of termination at 0°C in CH2Cl2 is 9 dm3 mol−1. From the kinetics, it is concluded that stage B is initiated by slow formation of a three‐membered cyclic sulfonium salt by an intramolecular nucleophilic attack of the last sulfide function of the polymer chain on the α‐carbon next to the sulfonium salt. Further evidence for this kind of re‐initiation is obtained from the observation that simple trialkylsulfonium salts are very poor initiators or completely incapable of initiating the polymerization, whereas under identical conditions 2‐thia‐alkylsulfonium salts give polymerizations without stage A which are similar to the stage B of the TEFB‐initiated reactions. A backbiting reaction, similar to the termination reaction, is responsible for the degradation of polymer (mainly) into cyclic tetramer. The molecular weights of the polymers, measured by gel permeation chromatography, are in reasonable agreement with the proposed mechanism.
Étude de la microstructure de polyéthylènes de basse densité chlorés en solution et en suspension
Authors: Humbert Gerard , Quenum Bienvenu M. , Pham Quang T. , Berticat Philippe , Vallet Georges
Published: April 2003

L'analyse par R.M.N. haute résolution de la microstructure de polyéthylènes basse densité chlorés soit en suspension soit en solution est entreprise et fait apparaître une différence fondamentale de constitution entre ces deux catégories de produits.

Les produits préparés en suspension peuvent schématiquement être considérés jusqu'à 65% de chlore comme des copolymères semi‐cristallins séquencés polyéthylène–polychlorure de vinyle et, au‐delà, comme des copolyméres amorphes de chlorure de vinyle, dichloro‐1,1 éthylène, dichloro‐1,2 éthylène et trichloro‐1,1,2 éthylène.

Les produits préparés en solution sont pratiquement chlorés de façon statistique et deviennent très rapidement amorphes. Au début de leur chloration la formation de groupement dichlorométhylène domine. Pour des teneurs en chlore plus élevées apparaissent des séquences polychlorure de vinyle qui deviennent prédominantes à 60% de chlore. Au‐delà de 60% de chlore se forment des unités dichloro‐1,2 éthylène.
Chemische synthese eines phagenspezifischen DNA‐fragments
Authors: Schott Herbert
Published: April 2003

Die Synthese eines Decadesoxyribonukleotids wird beschrieben, dessen Basensequenz dA‐G‐A‐A‐A‐T‐A‐A‐A‐A im Minus‐Strang der DNA des Phagen ϕX 174 vorkommt. Mit Hilfe dieses synthetischen Primers sollen weitere Bereiche der DNA des Phagen ϕX 174 sequenziert werden. Das Decanukleotid wird nach der Methode von Khorana et al. aus den geschützten Nukleotidblöcken

d(MeOTr)bzA‐ibuG, dpbzA‐bzA(Ac), dpbzA‐T(Ac) und dpbzA‐bzA‐bzA‐bzA(Ac) unter Verwendung von TPS als Kondensationsmittel in drei Kondensationsschritten aufgebaut.
Cationic polymerization of 3‐methylenecyclohexene and 2‐methyl‐1,3‐pentadiene
Authors: Imanishi Yukio , Kanagawa Shuichi , Higashimura Toshinobu
Published: April 2003

To investigate the effect of a cyclic structure on the reactivity of conjugated dienes in cationic polymerization, a cyclic diene 3‐methylenecyclohexene (1) and the corresponding linear diene 2‐methyl‐1,3‐pentadiene (2) were synthesized and polymerized. Cationic polymerizations and copolymerizations showed that 1 was more reactive than 2. The conjugated double bonds in 1 were proved to be less resonance‐stabilized than that in 2. However, the conjugate cation 1 was found to be more stable than that of 2. The combination of these two factors made the cyclic diene more reactive than the linear d+. Cationic polymerizations of 2 were fast and non‐stationary, giving low molecular weight polymers. The polymerizations proceeded mainly by the 1,4 route and to a smaller extent by the 1,2 route. A brief discussion on the stereochemistry in some electrophilic addition reactions of methyl‐substituted butadienes is also given.
Redoxharze auf der basis von 5,6‐dichlor‐3‐vinyl‐4,7‐dihydro‐1H‐4,7‐indazoldion
Authors: Acosta Francisco , Storck Winfried , Manecke Georg
Published: April 2003

Es wurde der Inhibierungseffekt von 5,6‐Dichlor‐3‐vinyl‐4,7‐dihydro‐1H‐4,7‐indazoldion (1a) auf die thermische Styrolpolymerisation, die Homopolymerisation von 1‐Acetyl‐4,7‐diacetoxy‐5,6‐dichlor‐3‐vinylindazol (2a) und von 4,7‐Diacetoxy‐5,6‐dichlor‐1‐vinylindazol (2c) sowie die vernetzende Copolymerisation von 2a mit 4,7‐Diacetoxy‐5,6‐dichlor‐1,3‐divinylindazol (2b) untersucht. Durch Verseifung und Propansulfonierung der vernetzten Polymeren wurden stabile Redoxharze dargestellt. Ihre Austausch‐ (1,8–2,2 mäq/g) und Redoxkapazität (2,5–4,0 mäq/g) sowie ihre Mittelpunktspotentiale (467–475 mV bei pH 1,66) wurden ermittelt.
Preparation of vinyl polymers as pH indicator
Authors: Hatanaka Hideo , Sugiyama Kazuo , Nakaya Tadao , Imoto Minoru
Published: April 2003

4‐(p‐Aminophenylazo)phenyl methacrylate (1a) and 4‐(p‐dimethylaminophenylazo)‐phenyl methacrylate (1b) were synthesized and characterized. These monomers were polymerized with 2,2′‐azoisobutyronitrile. The properties of these monomers and polymers as pH indicators are described.
Some anomalies in the kinetics of heterogeneous oxidative condensation reactions
Authors: Brooks Brian W. , Smith Roy M.
Published: April 2003

The rate of thiophenol oxidation in a catalysed gas‐liquid reaction is found to depend on the initial concentration of thiophenol but is independent of the changes in thiophenol concentration which occur during the course of the oxidation. The reaction rates have been used to construct a Lineweaver‐Burk plot. These results are compared with those which have previously been obtained in the oxidative condensation of 2,6‐dimethylphenol. The kinetic similarities between catalysed oxidative condensation reactions and enzyme reactions are discussed. It is shown that the linearity of the Lineweaver‐Burk plots does not ensure that the absorption of oxygen is chemically controlled. It is suggested that deductions which previous workers have made from the use of Lineweaver‐Burk plots must be treated with caution.
Polymerization of acrylonitrile by a ternary catalyst: FeCl3/2,2′‐dipyridyl/epoxypropane
Authors: Ikeda Masanori , Hirano Tsuneo , Uchida Akira , Tsuruta Teiji
Published: April 2003

The ternary system FeCl3/2,2′‐dipyridyl (1) (Dip)/epoxypropane (2) was found to be active as catalyst for the polymerization of acrylonitrile (4). The lack of one of the catalyst components makes the system inactive for polymerization. The active species is concluded to be partially alkoxylated ferric chloride complexed with 1, and the polymerization might be initiated by the alkoxy group of the complex. Copolymerization of 4 and styrene indicates that the polymerization is anionic at 30°C. At 50 and 80°C, however, both anionic and radical polymerizations seem to take place.
Vinyl polymerization by metal complexes, 14. Synthesis of 2‐substituted and 2,4‐disubstituted imidazole‐copper(II) complexes as initiator systems for vinyl polymerization
Authors: Shirai Hirofusa , Inaki Yoshiaki , Takemoto Kiichi
Published: April 2003

A series of the copper(II) complexes of the type CuL4X2 (L: ligand, X: anion) was prepared with the following substituted imidazoles as ligands 2‐ethyl‐ (1a), 2‐ethyl‐4‐methyl‐ (1b), 2‐phenyl‐ (1c), 2‐undecyl‐ (1d), and 2‐heptadecylimidazole (1e). The structures of these complexes were confirmed by elemental analysis, reflection spectra of the crystals as well as IR‐spectroscopy. Polymerization of acrylonitrile was tested in the presence of each imidazole‐copper(II) complex in dimethyl sulfoxide solution.
Étude des systèmes ternaires polymère/mélange de solvants en équilibre thermodynamique avec le solvant binaire correspondant
Authors: Hert Marius , Strazielle Claude
Published: April 2003

Nous avons obtenu l'équilibre thermodynamique entre les solutions ternaires de polymères en mélanges de solvants et les solvants binaires, en réalisant une dialyse de la solution ternaire par rapport au mélange de solvants. La solvatation préférentielle du polymère par un des deux solvants, qui se manifeste par des variations de composition du solvant binaire de part et d'autre de la membrane imperméable aux macromolécules, a été mise en évidence par réfractométrie différentielle et par mesures de densités, pour des solutions diluées et modéremment concentrées en polymère. Nous avons étudié un certain nombre de systèmes, ce qui nous a permis de discuter des avantages de ces moyens d'étude et de confronter les résultats aux prévisions théoriques.
Structural and thermodynamic characteristics of chlorinated polyethylenes, 2
Authors: Erä Väinö A.
Published: April 2003

A series of suspension chlorinated and chlorosulfonated polyethylenes (CPE and CSPE resp.) of varying chlorine contents were investigated. The ß‐ and γ‐relaxation processes are related to motions of CH2CHClCH2 and CH2 units in the chains of CPE and CSPE polymers, respectively. In isothermal crystallization, the fine structures of the polymers change gradually, as is shown by the variation in the pattern of the DSC curve and the shift of the melting peak.
Steric and electrostatic factors on the formation and the structure of polymeric cobalt(III) complexes
Authors: Tsuchida Eishun , Nishide Hiroyuki , Takeshita Michitaka
Published: April 2003

Polymeric cobalt(III)‐complexes (2a, b, c, e, f, g, h, i, j) were prepared by a substitution reaction between a polymeric ligand (1a or 1b) and a Co(III)‐chelate. They were characterized by elemental and spectroscopic analyses. The complexation rates of the Co(III)‐en‐ and Co(III)‐trien‐chelates were found to be smaller than those of the non‐charged Co(III)‐chelates. This retardation effect was explained by an electrostatic repulsion of the cationic polymeric complexes 2a, b or 2c. The degree of coordination (x) was found to reach a constant level of about 0,65 under the reaction conditions. This experimental x‐value of saturation was nearly equal to the value which was calculated statistically.
Kinetics of polymerization of 1,3‐dioxepane with the Al(C2H5)3/H2O catalyst system
Authors: Donescu Dan
Published: April 2003

The kinetics of the polymerization of 1,3‐dioxepane (DH) with the catalytic system Al(C2H5)3/H2O was studied. The dependence of the polymerization rate R0 of the monomer DH(M) may be represented by the equation:

The kinetic scheme which verifies the obtained results is that which takes into consideration in the starting period of the polymerization the existence of chain transfer to the monomer. The decrease of the polymerization rate and the diminishing of the intrinsic viscosity at high conversions points to the existence of chain transfer to the polymer in this stage of the reaction. The reaction rate constants of the chain transfer to the monomer are one order of magnitude higher than those of the transfer reaction to the polymer.
Untersuchungen von polymeren im massenspektrometer, 3. Fragmentierungsreaktionen oligomerer benzyle
Authors: Lüderwald Ingo , Montaudo Giorgio , Przybylski Michael , Ringsdorf Helmut
Published: April 2003

Beim thermischen Abbau von Polybenzylen im Massenspektrometer werden oligomere Benzylbruchstücke mit gesättigten (Phenyl‐, Alkyl‐) und ungesättigten (Chinonmethid)‐Endgruppen gebildet. Zur Differenzierung der thermischen und elektronenstoßinduzierten Abbaureaktionen wurden die Fragmentierungsreaktionen oligomere Benzyle vom Typ1a, bim Massenspektrometer untersucht. Bei Anwendung niedriger Elektronenstoßenergien wurden als Hauptfragmentierungsreaktionen Alkyl‐, α‐Benzyl‐ und β‐Benzylspaltung sowie die für 1,2‐disubstituierte Benzyle strukturspezifischeortho‐Umalgerung gefunden, die eine Differenzierung stellungsisomerer Oligobenzyle ermöglicht. Die genannten Reaktionen wurden durch Hochauflösungsmessungen und Registrierung zahlreicher metastabiler Zerfälle mit der “Defocusing”‐Technik nachgewiesen. Der Einfluß unterschiedlicher Substitution der Phenylringe und Methylengruppen auf das Fragmentierungsverhalten der oligomeren Benzyle wird diskutiert.
Cationic copolymerisation of 1,3‐dioxolane with 5‐methyl‐2,3‐dihydro‐2‐furanone initiated with triethyloxonium tetrafluoroborate
Authors: Yokoyama Yasuaki , Okada Masahiko , Sumitomo Hiroshi
Published: April 2003

The copolymerization of 1,3‐dioxolane (1) with 5‐methyl‐2,3‐dihydro‐2‐furanone (2) which has two functional groups, a CC double bond and a γ‐lactone ring, was carried out in nitrobenzene, dichloromethane, and toluene at 0 C with triethyloxonium tetrafluoroborate as initiator. NMR analysis of the microstructure of the copolymer disclosed that a random copolymer was formed in this system, and that the exclusive addition of the growing chain end of 1 to the CC double bond occurred in the cross‐propagation from 1 to 2. The highly selective reactivity of the growing species of 1 was discussed.

Homopolymerizability of 2 was also studied by using various cationic and radical initiators.
Ethylene‐propylene based terpolymers containing tricyclo[5.2.1.02,6]deca‐2,5,8‐triene
Authors: Cesca Sebastiano , Arrighetti Sergio , Priola Aldo , Duranti Publio V. , Bruzzone Mario
Published: April 2003

Tricyclo[5.2.1.02.6]deca‐2,5,8‐triene (1) (trivial name: dehydro‐isodicyclopentadiene) or a mixture of its methyl derivatives were used as termonomers to obtaine ethylene‐propylenetriene terpolymers (EPTM's) having unusual properties in the curing process, even at low levels of triene (ca. 1 wt‐%). Three types of catalyst systems have been investigated, i. e. based on VCl4, VO[O(CH2)3CH3]3, or V(acac)3 and (C2H5)2AlCl. Several parameters of the terpolymerization process were studied (e.g. Al/V mole ratio; catalyst and termonomer concentration; polymerization time; presence of a Lewis base or chain transfer agent) and their influence on Mv and EPTM composition were evaluated. Fractionation data and the use of model compounds allow to conclude that 1 enters EPTM chains randomly and by selective opening of the norbornenic double bond, whereas the conjugated diene system is involved in side‐reactions if the catalyst has some acid character or the concentration of the triene is above some critical values.
Kristallisations‐ und schmelzverhalten von copolymeren aus 3,3‐bis(chlormethyl)oxetan und ß‐propiolacton
Authors: Wiemers Norbert , Wegner Gerhard
Published: April 2003

Einkristalle von Copolymeren aus 3,3‐Bis(chlormethyl)oxetan und ß‐Propiolacton wurden bezüglich Schmelzverhalten, Schmelzenthalpie, Dichte und Langperiode untersucht. Aus der Messung der Schmelzenthalpie und der Dichte berechnen sich Kristallisationsgrade von 50—60% in guter Übereinstimmung mit einem Modell, welches den Ausschluß der aus ß‐Propiolacton (PL) entstandenen Grundbausteine von dem aus Sequenzen der 3,3‐Bis(chlormethyl)oxetan (BCMO‐)Einheiten aufgebauten Gitter verlangt. Im Vergleich zu reinem Poly‐BCMO wird die Dicke der Copolymereinkristalle nur wenig durch Änderung der Kristallisationstemperatur beEinflußt. Wegen des blockartigen Aufbaus der Copolymeren bestimmt die mittlere Sequenzlänge der BCMO‐Einheiten die Kristallitdicke. Im Bereich der Schmelztemperatur treten typische Rekristallisationsvorgänge auf. Das dabei stattfindende Langperiodenwachstum und seine Auswirkung auf den Schmelzvorgang wurden durch Untersuchungen an getemperten Einkristallen geklärt. Der PL‐Gehalt der Copolymeren beEinflußt deren Rekristallisationsgeschwindigkeit. Die beobachteten Schmelzpunktdepressionen von Einkristallen unterschiedlichen PL‐Gehalts können durch Kristallitgrößeneffekte beschrieben werden. In der Schmelze der Copolymeren +heinen die reinen BCMO‐ und die BCMO‐PL‐Sequenzen entmischt vorzuliegen. Beim Auflösen der Einkristalle tritt jedoch eine Mischung der verschiedenen Sequenzen und Grundbausteine des Copolymeren ein. Daher wird eine Depression der Lösungstemperatur beobachtet, die durch die zugehörige Mischungsentropie bedingt ist.
Chemical modification and conformation studies on bence jones protein
Authors: Liaw Wen‐Yi Vicki , Nakagawa Yasushi , Jirgensons Bruno
Published: April 2003

A λ‐type Bence Jones protein was chemically modified by carbamaylation of the ε‐amino groups of its lysine side chains and by nitration and reduction of its tyrosine residues. All 30 ε‐amino groups were carbamylated, but only 6 of the 14 tyrosine side chains were nitrated. The gross conformation of the macromolecules (shape) was not altered in these reactions, as tested by intrinsic viscosity and sedimentation coefficient determinations. Also, the immunoprecipitability was not affected by the chemical modification. However, circular dichroism (CD) spectra revealed slight to moderate changes in the conformational details within the macromolecules. The appearance of a positive CD band at 240 nm on nitration was caused by 3‐nitrotyrosine residues, whereas the new band at 300 nm was probably due to change of asymmetric environment of tryptophan chromophores.
Darstellung und charakterisierung von einigen neuen bis(1‐phenylvinyl)‐verbindungen
Authors: Lattermann Günter , Höcker Hartwig
Published: April 2003

Einige neue Bis(1‐phenylvinyl)‐Verbindungen (1b, c und 2a–d) wurden aus den entsprechenden Diacetylverbindungen und Phenylmagnesiumbromid dargestellt. Ihre IR‐, NMR‐und Massenspektren werden diskutiert.