bluuebunny/crossref_metadata_2025 huggingface dataset:
Ionic polymerization of cyclic ethers. II. Bulk polymerization of β‐methylglycidaldehyde in the presence of aluminum isopropoxide as a catalyst
Authors: Jedliński Zbigniew , Majnusz Jerzy
Published: April 2003

In the course of further investigations of ring‐opening polymerizations we have studied the bulk polymerization of β‐methylglycidaldehyde (βMG) by aluminum isopropoxide at 20 and 50°C.

The polymerization proceeds in two distinct stages. In the first stage the α.β‐epoxybutyl ester of α.β‐epoxybutyric acid (2.3‐epoxy‐n‐butyl‐1′.2′ ‐epoxybutyrate) (DßMG) is formed by a TISHCHENKO‐CLAISEN reaction.

In the second stage this ester gives a polyether (PßMG) by polymerization of the epoxy groups adjacent to the ester carbonyl. The pendent epoxy‐butyl groups are attached to the polyether by an ester linkage. Mechanisms are proposed for the formation of dimer and polymer.
Kinetik der radikalischen copolymerisation α‐substituierter styrole mit styrol. 1. Teil. Copolymerisation von α‐methylstyrol mit styrol oberhalb der ceiling‐temperatur von α‐methylstyrol
Authors: Fischer J. P.
Published: April 2003

Die radikalische Copolymerisation von α‐Methylstyrol mit Styrol läßt sich im Temperaturbereich von 60–150°C nach Gleichungen beschreiben, die WITTMER unter der Annahme abgeleitet hat, daß die Additionsreaktionen von α‐Methylstyrol reversibel sein können.

Hierbei genügt es, im Temperaturbereich von 60–110°C lediglich die Reversibilität von α‐Methylstyrol‐Additionsschritten an ein Kettenende mit α‐Methylstyrol als letzter Monomereinheit zu berücksichtigen. Für 150°C als Reaktionstemperatur ergibt sich, daß auch die Addition von α‐Methylstyrol an ein Styryl‐Kettenende meßbar reversibel ist, jedoch mit einer Gleichgewichtskonstante, die um einen Faktor 30 unter der für die α‐Methylstyrol‐Homopolymerisation liegt.

Aus der Retardierung der Styrolpolymerisation durch geringe Zusätze von α‐Methylstyrol werden die einzelnen Geschwindigkeitskonstanten und Aktivierungsenergien des Kettenwachstums und der Depolymerisation abgeschätzt.
Long chain branching and solution properties of low density polyethylene
Authors: Hama Tomohiko , Yamaguchi Kinya , Suzuki Tadao
Published: April 2003

The intrinsic viscosity, osmotic pressure and light scattering of solutions of fractionated samples of low density polyethylene (LDPE) were measured to study its long chain branching. The following relation was obtained between the two branching indices:

gη is the ratio of the intrinsic viscosities of the branched and linear polymers with the same molecular weight, and gs is the corresponding ratio of the radii of gyration. The average number of long branches per molecule, nw, was calculated according to the theory of ZIMM and STOCKMAYER derived for random branching, and it was found that the dependence of nw on the molecular weight is expressed by

with α = 0.85.

This relation indicates that the long branching frequency or density decreases gradually with molecular weight for LDPE.
Synthesis of copolymers. I. Copolymers of styrene and of α‐methylstyrene
Authors: Cunliffe A. V. , Hubbert W. J. , Richards D. H.
Published: April 2003

The compositions of copolymers formed by reacting styrene or α‐methylstyrene (M) with lithium in tetrahydrofuran in the presence of varying amounts of alkyl dibromides (RX2) have been studied. Regular copolymers of structure are formed at 2:1 monomer to dibromide molar stoichiometry, but they become less regular and richer in monomer as the proportion of dihalide decreases. α‐Methylstyrene copolymers change systematically with reactant ratios and a series of materials can be prepared with different glass transition temperatures which can be related to the copolymer compositions. The fast rate of anionic homopropagation of styrene after consumption of the dihalide prevented pure copolymer from being prepared free of homopolystyrene. However, it is shown that the composition of the styrene copolymers is much more sensitive to the initial reactant ratios than is that of the α‐methylstyrene copolymers.
Synthesis of copolymers. II. Copolymers of butadiene and of isoprene
Authors: Cunliffe A. V. , Hubbert W. J. , Richards D. H.
Published: April 2003

The compositions of copolymers formed by reacting butadiene or isoprene (M) with lithium in tetrahydrofuran in the presence of varying amounts of alkyl dihalides have been studied. When butadiene was reacted with dibromo‐p‐xylene, it was found that the dihalide predominantly dimerised by a WURTZ condensation mechanism before reacting with butadiene thus giving a copolymer of general form
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the value of q depending on the initial reactant ratio.

Isoprene was reacted with bis(2‐chloroethyl)ether and with dibromodecane. With the former reagent, and to a lesser extent with the latter, there is evidence that some initiation takes place by direct reaction of the halide with lithium. Only very low molecular weight materials were obtained with this monomer and bis(2‐chloroethyl)ether. The reasons for this are discussed.
Anionic copolymerization of acrolein with aldehydes
Authors: Mateo J. L. , Sastre R.
Published: April 2003

Unsaturated copolyacetals have been prepared by anionic copolymerization of acrolein with aldehydes, such as, acetaldehyde, benzaldehyde, propionaldehyde, pivaldehyde and others.

The dependence of the structure of the copolymers on the dielectric constant of the solvent, and on the temperature, the aldehyde, the catalyst and the extension of the reaction has been studied.
Multimerisation: Assoziation und Aggregation. XII. Untersuchungen an Poly(vinylacetat‐co‐vinylalkoholen)
Authors: Elias Hans‐Georg , Vogt Peter
Published: April 2003

Poly(vinylacetat‐co‐vinylalkohole) mit Vinylalkoholgehalten zwischen 0 und 21 Mol‐% wurden durch Alkoholyse von nicht‐esterbrückenverzweigten Polyvinylacetaten hergestellt. Die Copolymeren assoziierten nach Streulichtmessungen bei 25°C nicht in Methanol, Aceton und Butanon. Dieses von dem der Poly(methylmethacrylat‐co‐äthylenglykolmethacrylaten) abweichende Verhalten wird durch die Ausbildung von intermeraren Wasserstoffbrückenbindungen zwischen benachbarten Vinylalkohol‐Gruppierungen erklärt.
Über die reaktionsfähigkeit der vinylgruppen in vernetzten divinylbenzol‐polymeren und styrol/divinylbenzol‐copolymeren II. Über die anlagerung von n‐butyllithium
Authors: Kühnle Dietmar , Funke Werner
Published: April 2003

Es wurden vernetzte Mikrogelpartikel mit anhängenden Vinylgruppen durch radikalische Polymerisation von p‐Divinylbenzol (p‐DVB), technischem DVB und Styrol/DVB‐Gemischen hergestellt.

Die anhängenden Vinylgruppen reagieren mit n‐Butyllithium (BuLi) in Benzol unter Ausbildung der charakteristischen roten Farbe. Der Reaktionsumsatz wurde aus der Aktivität der markierten Reaktionsprodukte berechnet. Die Abnahme der Vinylintensität bei dieser Reaktion wurde mit Hilfe der IR‐Spektroskopie quantitativ verfolgt.

Die heterogene Reaktion des BuLi mit den anhängenden Vinylgruppen ist nicht auf die Oberfläche der Mikrogelpartikel beschränkt, sondern erfaßt auch Vinylgruppen, die im Innern der Partikel sitzen. Der Umsatz in der Anfangsphase der Reaktion war der spezifischen Oberfläche und dem Vinylgruppengehalt der meisten Polymeren proportional. Bei diesen Polymeren ist also die Konzentration der Vinylgruppen an der Partikeloberfläche annähernd gleich wie im Innern der Partikel. Die Reaktion mit BuLi erfolgt langsamer, und der erreichbare Umsatz ist niedriger als bei der Reaktion mit Hg(II)‐acetat.
Monte‐Carlo‐rechnungen an makromolekülmodellen
Authors: Bruns Wolfgang
Published: April 2003

Für zwei Perlenkettenmodelle im gitterfreien Raum wurden mit Hilfe von Monte‐Carlo‐Methoden unter Berücksichtigung des “ausgeschlossenen Volumens” Zufallsketten bis zu einer Anzahl von etwa 100 Bauelementen erzeugt. Sie dienten zur Bestimmung der Verteilungsdichten des Fadenendenabstands (I), des Trägheitsradius (II) und der Bauelemente um den Schwerpunkt (III). Dabei zeigte sich, daß die GAUSS sche Verteilung – besonders bei den längeren Ketten – im Falle (I) und (III) eine brauchbare erste Näherung darstellt, wenn man mit den “experimentell” bestimmten quadratischen Mittelwerten rechnet. Nicht so befriedigend verläuft die analoge Anwendung der von FLORY für ungestörte Ketten aufgestellten Verteilungsfunktion im Falle (II). Zur genaueren Beschreibung der Verteilungen wurde die Gleichung W(x)dx = Cxϵ exp (–x/xn)tdx herangezogen und über die reduzierten Momente die Parameter ϵ und t bestimmt. Es wurde versucht, diese Werte auch für sehr lange Ketten durch Extrapolation der reduzierten Momente zu ermitteln. Die will‐kürlich zu wählende Extrapolationsmethode beeinflußt jedoch in gewissem Maße die Ergebnisse. Sie können deshalb nicht als sehr zuverlässig angesehen werden. Dessenungeachtet befinden sie sich in grober Übereinstimmung mit den Werten anderer Autoren, die diese für (I) für Gittermodelle ermittelt hatten.
Molekulare Konformation, hydrodynamische, dynamooptische und elektrooptische Eigenschaften von Polymeren mit Leiterstruktur in Lösungen
Authors: Tsvetkov Viktor N.
Published: April 2003

Die Eingentümlichkeit des doppelkettigen Baus von Leiterpolymeren, die zu einer starken Verringerung der Biegsamkeit der Molekülkette führt, erfordert die Ausarbeitung neuer theoretischer und experimenteller Methoden bei der Aufklärung der Struktur und der physikalischen Eigenschaften dieser Polymeren.

Es werden experimentelle Ergebnisse der Untersuchungen von Konformation, hydrodynamischen, optischen und elektrischen Eigenschaften in Lösung für eine Reihe von Leiterpolymeren aus Polysiloxanketten angeführt. Diese experimentellen Ergebnisse werden unter Hinzuziehung moderner Theorien (Theorie von Persistenz‐Ketten, „wurmförmiger”︁ Ketten und Ketten mit nichtgaußschen optischen Eigenschaften) ausgewertet und quantitative Schlußfolgerungen über molekulare Konformation, Biegsamkeit und mögliche Defekte der doppelkettigen molekularen Struktur der untersuchten Leiterpolymeren unterschiedlicher chemischer Struktur gezogen.
Üuber Koordinationspolymere aus Eisen(III)‐Acetylacetonat und Diorganophosphinisäuren
Authors: Golgoţiu T. , Roşa I.
Published: April 2003

Koordinationspolymere aus Eisen(III)‐acetylacetonat und Diäthyl‐, Dibutyl‐, Diäthylthio‐, Diäthyldithio‐, Diphenylthio‐ und Diphenyldithio‐phosphinsäure wurden nach verschiedenen Verfahren hergestellt. Die Produkte sind in organischen Lösungsmitteln nur wenig löslich, sie haben eine relative große thermische Beständigkeit; die Molekulargewichte liegen zwischen 4000 und 12000. Einige der Polymeren haben Halbleitereigenschaften. Die Struktur wird diskutiert.
General statistics of sequences during polymer analogous reactions
Authors: Klesper E. , Johnsen A. , Gronski W.
Published: April 2003

When converting a homopolymer, consisting of monomer units A, by a polymer analogous reaction into a copolymer, composed of monomer units A and B, the reversible reaction A ⇄ B may be kinetically influenced by the two flanking monomer units. The distribution of the blocks along the chain of the copolymer is shown to be random in the sense that the probability of a block of given length does not depend on the length of adjacent blocks. As opposed to the random distribution of the blocks in the chain, the frequency distribution of the block lengths conforms to block probabilities determined by a non‐MARKOVian statistics of monomer units. The exact way to use conditional probabilities for calculating the probabilities of sequences is presented. A method for deriving rate equations of polymer analogous reactions and their use for proving the random distribution of the blocks is described. Model copolymers obtained by Monte Carlo simulation of polymer analogous reactions confirm the random statistics of blocks and the non‐MARKOVian statistics of monomer units.
Production of organometallic polymers by the interfacial technique. XXV. Synthesis of oligomeric silylhydrazines
Authors: Carraher Charles E. , Wang Long‐Shyong
Published: April 2003

Polymers of the form below were prepared by the interfacial method via the condensation of silanes with hydrazines employing a modified nonaqueous system using acetonitrile and liquid hydrocarbons. IR frequency band assignments are given.

The products are oligomeric.
The polymerization of furan on surfaces
Authors: Livingston H. K. , Senkus Raymond , Hsieh John Tai‐Tung , Kresta Jiri
Published: April 2003

Furan is a monomer that has but a single conformation and therefore represents a promising candidate for studies of adsorption polymerization with molecules in controlled orientation. It has been adsorbed on a well‐characterized carbon black at known surface concentrations and then polymerized. Spontaneous polymerization occurs to some extent, but irradiation with high‐energy electrons or γ‐rays or the introduction of tin tetrachloride vapors initiates a more complex polymerization.

The polymerization of furan in the solid (glassy) state has been accomplished for the first time, using γ‐ray irradiation. As in the case of γ‐ray‐initiated polymerization of liquid furan or adsorbed furan, this polymerization occurs after several hours at room temperature. All the various radiation‐initiated polyfurans that have been studied are rather similar in composition. Molecular weights are low, and infrared absorption occurs in the same regions.

Furan vapor polymerizes on the surface of aqueous perchloric acid. This polymer, after isolation from acid‐free water, is slightly cross‐linked and has a high concentration of primary hydroxyl groups. It has the composition expected for a cationically polymerized furan after acid hydrolysis.
Über den mechanismus der anionischen polymerisation von acrylnitril mit triphenylphosphin. 7. Mitt. über makrozwitterionen
Authors: Jaacks Volker , Eisenbach Claus Dieter , Kern Werner
Published: April 2003

Die anionische Polymerisation von Acrylnitril mit Triphenylphosphin als Initiator bei 30°C in Dimethylformamid wurde untersucht. Die Polymerisation verläuft sehr langsam; der Polymerisationsgrad nimmt mit zunehmender Reaktionszeit nach Durchlaufen eines Maximums stetig ab.

Der für die Polymerisation von Vinylverbindungen mit nichtionischen LEWIS‐Basen angenommene Zwitterionenmechanismus konnte hierbei nicht bestätigt werden. Mittels IR‐und UV‐Spektroskopie sowie emissionsspektralanalytischer Phosphorbestimmung sowohl bei dem Rohpolymeren als auch bei den durch Umfällungen und Gelchromatographie fraktionierten Polymerproben ließ sich nachweisen, daß keine kovalente Bindung des Phosphors an das Polymere vorliegt, sondern lediglich Phosphoniumionen \documentclass{article}\pagestyle{empty}\begin{document}$\left( {{\rm C}_6 {\rm H}_5 } \right)_3 \mathop {\rm P}\limits^ \oplus - {\rm CH}_2 {\rm CH}_2 {\rm CN}$\end{document} im Rohpolymeren enthalten sind. Deren Entstehung läßt sich so erklären, daß durch das Zwitterion \documentclass{article}\pagestyle{empty}\begin{document}$\left( {{\rm C}_6 {\rm H}_5 } \right)_3 \mathop {\rm P}\limits^ \oplus - {\rm CH}_2 \mathop {\rm C}\limits^ \ominus {\rm HCN}$\end{document}, gebildet aus Triphenylphosphin und Acrylnitril, ein Proton vom Monomeren abstrahiert wird; das so entstandene Anion \documentclass{article}\pagestyle{empty}\begin{document}${\rm CH}_2 \hbox{=\hskip-1pt=} \mathop {\rm C} \limits ^\ominus \hbox{---} {\rm CN}$\end{document} löst das Kettenwachstum aus.

Die durch spektroskopische Endgruppenbestimmung ermittelte Zahl der Polymeranionen steht in guter Übereinstimmung mit den im Rohpolymeren vorhandenen Phosphoniumionen \documentclass{article}\pagestyle{empty}\begin{document}$\left( {{\rm C}_6 {\rm H}_5 } \right)_3 \mathop {\rm P}\limits^ \oplus - {\rm CH}_2 {\rm CH}_2 {\rm CN}$\end{document}.
Pyrolysis‐gas chromatographic studies on the structure of ethylene/propylene copolymers
Authors: Seno Hiroshi , Tsuge Shin , Takeuchi Tsugio
Published: April 2003

Pyrolysis‐gas chromatographic studies of chlorinated ethylene/propylene (Cl‐(E/P)) copolymers have been carried out to obtain informations about the microstructure of the nonsubstituted E/P copolymers. The pyrograms of the E/P copolymers show various olefin peaks, while on the pyrograms of the Cl‐(E/P) copolymers, the main peaks represent aromatic compounds such as benzene, toluene, xylene isomers and trimethylbenzene isomers which give good informations about the microstructure of the nonsubstituted copolymers. The concentration of triads in the E/P copolymers and the thermal decomposition of the Cl‐(E/P) copolymers are discussed.
Some aspects of the metathesis catalyst
Authors: Höcker Hartwig , Jones Frank R
Published: April 2003

The metathesis reaction of cyclooctene was investigated with respect to the solvent, the catalyst, and the ratio of its components. A necessary condition for an active metathesis catalyst appears to be the presence of two transition metal‐carbon bonds in a complex of the transition metal compound with an aluminum halide. A structure for the active complex is proposed.
Photo‐sensitized polymerization by S.S′‐diphenyldithiocarbonate
Authors: Tsuda Kazuichi , Kosegaki Kimio
Published: April 2003

In order to study the thiyl radical, S.S′‐Diphenyldithiocarbonate (DTC) was used as a photo‐sensitizer of radical polymerization of styrene, methyl methacrylate and acrylonitrile, and the rate of decomposition of DTC was also studied. DTC was decomposed into phenyl thiyl radical and carbon monoxide by ultra‐violet light, but it was not decomposed by heat at 60°C. The thiyl radical which derived from the photo‐dissociation of DTC initiated the radical polymerization, and also worked as a terminator or a chain transfer agent.

The kinetic of photo‐sensitized polymerization by DTC coincided with the ordinary radical polymerization mechanism.
Vinyl polymerization initiated by the binary system of tetraphenylborate salts and organic acids
Authors: Sato Tsuneyuki , Kashino Eiichi , Fukumura Naoki , Otsu Takayuki
Published: April 2003

It was found that the binary system of tetraphenylborate (TPB) salts and organic acids could serve as radical initiator of vinyl polymerization. From the effects of structures in TPB salts and acids on the polymerization activity, it was concluded that the reaction between the TPB ion and the proton of the acid was important in the initiating radical production. Using dimethylbenzylanilinium TPB and trichloroacetic acid (TCA), the rate of polymerization of methyl methacrylate (MMA) was found to be proportional to the square roots of the concentrations of both TPB salt and TCA, indicating that the system induced radical polymerization. The copolymerization by this system with styrene resulted in a composition curve which was in agreement with that obtained with ordinary radical copolymerization.

From the product analysis and spin trapping technique for the reaction of sodium TPB with TCA, it was concluded that triphenylboron is produced first and decomposes into the phenyl radical which initiates the polymerization. On the basis of the results obtained, the initiation mechanism is presented and discussed.
Unique polyethylene morphologies produced under extrusion conditions
Authors: Southern John H. , Weeks Norman , Porter Roger S. , Crystal Richard G.
Published: April 2003

Unusual morphologies have been shown to be produced in high density polyethylene near its melting point and under selective conditions of orientation and pressure existing in an Instron capillary extrusion rheometer. Points of study involve the remarkably high optical clarity and tensile moduli for the morphologies produced in these filaments. Details of the crystallization procedure are provided. The morphologies resulting from the Instron procedure have been analyzed by several different techniques. X‐ray, calorimetry, microscopy and modulus data are discussed. The transparent filaments are composed of a large number of microfibers having a high degree of crystalline orientation parallel to the capillary axis. Electron diffraction and calorimetric studies indicate that a portion of the strands have an unusually high degree of order. Structural models for the strands are also proposed.
Organoaluminum catalysts for polymerization reactions. The effect of metal hydroxides on the catalytic activity of the Al(C2H5)3/H2O system
Authors: Aoyagi Takanobu , Araki Takeo , Tani Hisaya
Published: April 2003

The catalytic activity of the system Al(C2H5)3/H2O was investigated. Instead of pure water aqueous solutions of inorganic bases were reacted with Al(C2H5)3 in toluene/diethyl ether media. A uniform soft gel‐like product was readily obtained in this reaction (H2O/Al(C2H5)3 ∼ 1.0–1.5) differing from the heterogeneous nature of the product obtained with pure water. The polymerization of acetaldehyde proceeded with higher stereo‐regularity in this system Al(C2H5)3/aqueous inorganic base. The polymerization behavior and the stoichiometric reaction between the catalyst and the monomer (ethyl acetate formation) indicate that there seem not to be significant differences in the active species of Al(C2H5)3/aqueous inorganic base and Al(C2H5)3/H2O systems. Improved stereospecific polymerization in the presence of inorganic bases is discussed with respect to the formation of a cross‐linked product in the Al(C2H5)3/H2O system in the preparation of the catalyst.
Über die polymerisation des 2‐chlor‐2‐oxo‐1.3.2‐dioxaphospholans
Authors: Vogt Walter
Published: April 2003

Bei der ringöffnenden Polymerisation des 2‐Chlor‐2‐oxo‐1.3.2‐dioxaphospholans (I) besteht prinzipiell die Möglichkeit zur Bildung zweier verschiedenartiger Polymerer: eines polymeren Säurechlorids, dessen hauptkette eine Polyesterstruktur aufweist (II), oder eines β‐Chloräthylesters der Polyphosphorsäure, d.h. eines Polymeren mit rein anorganischer Hauptkette (III).
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Das Experiment zeigt, daß I durch Erhitzen oder schneller und schonender durch verschiedene Katalysatoren (z. B. NaF, AlCl3, N(CH3)4Cl, Tetraphenylphosphoniumsalze, Triphenylphosphin, Triphenylphosphinoxid) in ein Polymers übergeht, das in der Hauptkette zu mindestens 90% die Struktur III und zu höchstens 10% die Struktur II aufweist und das stark vernetzt ist.

Kinetische Messungen zeigen, daß die spontane Polymerisation nach einem anderen Mechanismus als die katalytisch beschleunigte ablaufen muß. Die Ergebnisse stehen mit der Annahme in Einklang, daß die rein thermische Polymerisation im Sinne einer Stufenreaktion durch aufeinanderfolgende, voneinander unabhängige Additionsschritte erfolgt, währ und die katalytisch beschleunigte Reaktion eine über Ionen verlaufende kettenreaktion ist. Die Wirkung der verschiedenen katalytisch aktiven Substanzen besteht darin, direkt oder indirekt freie Chloridionen zur Verfügung zu stellen, die ihrerseits den eigentlichen Katalysator darstellen.
Etude comparée des propriétés mécaniques dynamiques des formes I et II du polybutène‐1. Cinetique de transformation II → I
Authors: Decroix Jean‐Yves , May Jean‐François , Vallet Georges
Published: April 2003

L'étude des propriétés mécaniques et électriques du polybutène lors de la transformation de la forme I1 en forme I montre la présence d'une discontinuité correspondant au temps de demi‐transformation.

La variation des propriétés mécaniques dynamiques à basses fréquences en fonction de la température a mis en évidence l'existence de deux mécanismes de relaxation: β et γ. Les résultats obtenus sur le pic β confirment les hypothèses émises dans notre laboratoire.
Poly(1.4‐phenylen‐1.1‐diaryläthylene)
Authors: Braun D. , Platzek U.
Published: April 2003

Die vorliegende Untersuchung befaßt sich mit der Bildung, der Struktur und der Fraktionierung von Poly(1.4‐phenylen‐1.1‐diaryläthylenen). Die Darstellung erfolgt aus Diphenyl‐p‐alkylphenyl‐methylhalogeniden und Pyridin durch radikalische Polymerisation der intermediär gebildeten α.α‐Diaryl‐1.4‐chinodimethane. Die Struktur der Polymerisate wird durch NMR‐spektroskopische Untersuchungen und mit Hilfe von Modellverbindungen aufgeklärt. Die Auftrennung der relativ niedermolekularen Produkte erfolgt an Polyvinylacetat‐Gelen. Im Zusammenhang mit früheren Untersuchungen wird ein Polymerisationsschema vorgeschlagen.
Über die inhibierung radikalischer polymerisationen durch aromatische hydrazyle. 1. Reaktionen von triarylhydrazinen und ‐hydrazylen mit radikalen aus azoisobutyronitril
Authors: Braun Dietrich , Peschk Günter
Published: April 2003

Es wird über die Reaktionen berichtet, die zwischen den Radikalen α,α‐Diphenyl‐β‐pikrylhydrazyl (DPPH), α,α‐Diphenyl‐β‐[2,4,6‐tris(methoxycarbonyl)‐phenyl]‐hydrazyl (DPTH), α,α‐Diphenyl‐β‐(2,4,6‐tricyanophenyl)‐hydrazyl (DPTCH) und α,α‐Diphenyl‐β‐pentaphenylcyclopentadienyl‐hydrazyl (DPCPDH) einerseits und Radikalen aus Azoisobutyronitril andererseits in Gegenwart und Abwesenheit von Luftsauerstoff stattfinden. Nur beim DPTH findet dabei praktisch ausschließlich eine Wasserstoffübertragung unter Bildung des Hydrazins statt, während alle anderen genannten Hydrazyle in wechselndem Maße durch angreifende Radikale substituiert oder and der NN‐Bindung gespalten werden.
Substituenteneinfluß auf die kinetik des thermischen zerfalls von unsymmetrischen azonitrilen und azodinitrilen
Authors: Kerber Robert , Nuyken Oskar
Published: April 2003

Unsymmetrische Azonitrile der allgemeinen Form R1C6H4NNC(CN)(R2)(R3) (I), die zum Teil erstmals dargestellt wurden, zerfallen in Lösung zwischen 145 und 170°C mit einer Aktivierungsenergie von 40±2 kcal/Mol nach 1. Ordnung. Eine Beeinflussung der Zerfallsgeschwindigkeit und der Aktivierungsenergie durch Lösungsmittel konnte nicht festgestellt werden. Bei geeigneter Kombination der Substituenten R1, R2und R3variieren die Halbwertszeiten bis zu einem Faktor 10.

Azodinitrile R1C6H4NNC(CN)2(R2) (II) zerfallen in Lösung im Temperaturbereich 70–105°C ebenfalls nach 1. Ordnung, wobei in diesem Falle jedoch, abhängig von den Substituenten, Aktivierungsenergien zwischen 27 und 34 kcal/Mol gemessen wurden. Aufgrund der bei der thermischen Zersetzung entwickelten, nicht stöchiometrischen Stickstoff‐Volumina wird ein Reaktionsmechanismus postuliert, der die nicht synchrone Spaltung der beiden CN‐Bindungen der Azoverbindung voraussetzt.
The addition halogenation of polyalkenamers. III. Existence and interpretation of stereospecificity in chlorine. Addition to polyalkenamer double bonds
Authors: Dall'Asta G. , Meneghini P. , Bassi I. W. , Gennaro U.
Published: April 2003

The addition chlorination of a series of trans and cis polyalkenamers yields poly(1,2‐dichloroalkamer)s characterized by a certain degree of crystallinity. By X‐ray analysis of the polymers and examination of model compounds, the observed crystallinity has been shown to be due to stereoregularity in sequences of monomeric units.

The question whether this stereoregularity has to be attributed to stereospecificity in chlorine addition or to the statistical occurrence of units having the same configuration is examined in view of X‐ray data and of steric induction in model compounds. A hypothesis concerning the mechanism of chlorine addition is proposed.
Identification of free radicals produced by the radiolysis of poly(methyl methacrylate) and poly(methyl acrylate) at 77°K
Authors: Geuskens G. , David C.
Published: April 2003

The evolution of the ESR spectra of poly(methyl methacrylate) (PMM) and poly(methyl acrylate) (PMA) gamma irradiated at liquid nitrogen temperature has been studied as a function of temperature between 100°K and 320°K. In both cases, six radicals have been identified which are already present at 100°K. Some of these are a direct consequence of high energy irradiation while others are due to subsequent hydrogen transfer reactions. The results are discussed on the basis of a mechanism previously proposed for the radioysis of PMM.
Caractérisation de réactions primaires de dégradation oxydante au cours de l'autoxydation des polyoxyéthylènes à 25°C: Étude en solution aqueuse avec amorçage par radiolyse du solvant. IV. Diéthylèneglycol: Produits d'oxydation et schéma cinétique
Authors: Decker Christian , Marchal Jean
Published: April 2003

L'autoxydation du diéthylèneglycol (DEG) en solution aqueuse, amorcée B 25°C par les radicaux HO• provenant de la radiolyse de l'eau, conduit aux produits primaires suivants : hydroperoxydes organiques, eau oxygénée, aldéhyde du DEG, monoformiate de glycol, formaldéhyde, acide formique, éthylèglycol et glycolaldèhyde. La presence de ces produits indique que les réactions d'hydroperoxydation et d'oxydation de la fonction alcool terminale sont en compétition avec des réactions de degradation oxydante provoquant des coupures de la molécule de DEG. Ces coupures résultent de la décomposition monomoléculaire des deux types de radicaux peroxyles secondaires selon des mécanismes à 4 et à 6 centres. Les radicaux alcoxyles primaires libérés par ces réactions participent à la propagation des chaînes d'autoxydation et assurent leur terrninaison.
Solvent systems with required optical and thermodynamic properties and their application in light scattering from dilute solutions of copolymers or polymer mixtures
Authors: Kratochvǐal Pavel , Sedláček Blahoslav , Straková Dagmar , Tuzar Zdeněk
Published: April 2003

Sometimes, it is desirable in light scattering measurements on copolymers (or polymer mixtures) that the solvent has definite refractive and thermodynamic properties. Such solvents can, e.g., mask optìcally one copolymer component and be theta solvents for the polymer system studied. This enables the other copolymer component to be measured directly by light scattering. These solvent systems have to be generally ternary mixtures. Some optical and thermodynamic properties of mixed solvents are discussed. The application of ternary solvent systems is illustrated by measurements of butadiene/styrene block copolymers ((poly)butadiene‐b‐styrenes)) in acetophenone/cyclohexane/ethanol mixtures. The experimental limitations of this approach are demonstrated on the example of poly(styrene‐co‐methyl methacrylate).
The reactions of hydroxymethylated 2‐methoxy‐4,6‐diamino‐s‐triazine in an acidic aqueous solution
Authors: Tashiro Tatsuo
Published: April 2003

The kinetics of the reaction of hydroxymethylated 2‐methoxy‐4,6‐diamino‐s‐triazine (II) was studied at 35°C in aqueous solution at pH‐values between 2,8 and 1,8. The average degree of formaldehyde substitution of II was 3,39. The reactions were found to proceed through both cleavge and methylene bond formation of the methylol groups under elimination of formaldehyde and water, respectively. The reaction rates were determined by measuring methylol groups and liberated formaldehyde with iodometric and sodium sulfite methods. The rate constant km of methylene bond formation became maximum at [H3O⊕] = [H2O]/K1 (K1: the equilibrium constant of the conjugated acid formed from the reaction of II with acid). The rate constant kc of cleavage increased with decreasing pH. The activation energies of cleavage (Ec) and of methylene bond formation (Em) were calculated at 20,4 and 21,4 kcal·mole−1, respectively.
The structure of molecular aggregates in dilute solutions of poly(vinyl chloride) in tetrahydrofuran
Authors: Lyngaae‐J∅︁rgensen J∅︁rgen Helge
Published: April 2003

The structure of the aggregates found in dilute solutions of PVC with tacticity 0,53 in THF has been investigated. It is shown that a model of an aggregate describing it as a composition of 10 to 15 single molecules bound together by a crystalline nucleus, is in accordance with the experimental evidence from light‐scattering and GPC analysis.
The interactions between polymerization initiators and inhibitors in solution V. The reaction between benzoyl peroxide and p‐benzoquinone in carbon tetrachloride; some observations on the induced decomposition of the peroxide
Authors: Yassin Ahmady. A.
Published: April 2003

The reaction between benzoyl peroxide and p‐benzoquinone in CCl4 was investigated by isolation and identification of the reaction products. At peroxide/quinone ratios ≥ 3 only quinonoid products of the spontaneous decomposition of the peroxide are formed. At ratios < 3 the peroxide undergoes induced decomposition by both trichloromethyl and phenyl radicals. The induced decomposition involves the formation of radical intermediates which undergo intermolecular disproportionation, but not intramolecular rearrangement to form p‐trichloromethylbenzoyloxy radicals, p‐phenylbenzoyloxy radicals, and their corresponding acids. The p‐trichloromethylbenzoyloxy radicals are captured by benzoquinone to form 2‐(p‐trichloromethylbenzoyloxy)‐1,4‐benzoquinone and a considerable amount of quinonoid resins. A correlation between the electron‐donating or accepting property of a radical and its capability to induce the decomposition of the peroxide was developed.
On the possibility of molecular weight fractionation during isothermal crystallization
Authors: Kamide Kenji , Ogata Takashi
Published: April 2003

An attempt is made to clarify the possibility of molecular weight fractionation during isothermal crystallization studied by computer simulation technique and experiments on Marlex 50 by differential scanning calorimetry. The basic equation: [dC(t)/dt]t=τ = F(τ) of the KAWAI theory (where, dC(t)/dt is the rate of crystallization, F(τ) is the distribution function of retardation time τ) can only be valid when the broadness of F(τ), as defined by the ratio of maximum τ to minimum τ is 102 or greater. The isothermal crystallization curve (ICC) was calculated for Marlex 50 at various temperatures Tc assuming different degree of fractionations, x, which is the weight fraction of the polymer obeying the complete fractionation. When partial fractionation occurs, even to a very small extent, during isothermal crystallization, (1) ICCs are not superimposable, even when the exponent n in the AVRAMI's equation is identical for mono‐disperse polymer components having different molecular weight, and (2) n decreases with time, this tendency becomes more significant at higher Tc for larger x and at the final stage of crystallization. By comparing the experimental data with the theoretical curves, x = 0,15–0,25 was obtained. This implies that the fractionation with respect to molecular weight occurs, though partially, during isothermal crystallization.
Conformational studies of optically active poly(oxyisobutylidenecarbonyl) [poly(L‐α‐hydroxyisovaleric acid)] and its oligomers
Authors: Matsuo Shunji , Tohara Akifumi , Iwakura Yoshio , Iwata Kaoru
Published: April 2003

Optical rotatory dispersion (ORD) and circular dichroism (CD) of poly(oxyisobutylidenecarbonyl) (II) were investigated and compared with those of its optically active oligomers (III). The two‐term DRUDE equation was applied to analyze the ORD curves using n‐π*‐ and π‐π*‐transition bands as the critical wavelengths, λ0 and λ1, respectively. No drastic difference in ORD curves between the polymer and oligomers was detected in chloroform, which suggests that the polymer has no special conformation. On the other hand, in dioxane and acetonitrile λ1 of the polymer II shows a red shift in comparison with that of its oligomers.
Structure of oligourethane, 5. Micro structure of solution grown crystals
Authors: Nagura Masanobu , Tagawa Hiroyuki , Wada Eiichi
Published: April 2003

To study the dependence of the micro structure of oligomer crystals on the degree of polymerization, the small and wide angle X‐ray scattering of the oligomer α‐acetoxy‐ω‐methoxyoligo(oxypentamethyleneiminocarbonyl), CH3CO[O(CH2)5NHCO]nOCH3, having strictly homogeneous molecular weight, and of the corresponding polymer were investigated, together with the IR absorption spectra, the density and the thermal properties.

The solution grown crystals of oligomers and of the polymer are composed of the two‐phase structure. One is the crystalline phase having the ordered high density, and the other one is the intercrystalline phase of low density occupied by mobile molecular chain ends. The structure of the crystalline phase above trimer is similar to that of the dimer crystal, and the molecular motion in the intercrystalline phase is the local mode motion. This twophase structure could be illustrated by one dimensional density distribution having trapezoidal profile.
Mathematical properties of polydisperse systems, 1. General relations
Authors: Greschner G. S.
Published: April 2003

In the present paper the connection between an arbitrary polydisperse property and the molecular weight distribution is investigated using exact mathematical methods. On the basis of the superposition principle a general equation is derived which can be applied e.g. to the polydispersity problems connected with the Gel Permeation Chromatography, to the light scattering from dilute solutions of high polymers, or the ultracentrifuge. From this point of view, each of these phenomena is described by help of a linear operator with a special kernel, the analytical or numerical inversion of the operator yielding the molecular weight distribution of the system by help of an uniform algorithm.
Berechnung der ungestörten dimensionen von vinylpolymeren mit unterschiedlichen seitenketten. Poly(propyläthylen), poly(äthyläthylen), polystyrol
Authors: Biskup U. , Cantow H.‐J.
Published: April 2003

Für Poly(propyläthylen) (Poly‐n‐penten‐1), Poly(äthyläthylen) (Poly‐n‐buten‐1) und Polystyrol wurden mit dem FLORY‐Modell der rotationsisomeren Zustände die ungestörten Dimensionen 〈r〉/nl2 sowie deren Temperaturkoeffizienten berechnet. Sowohl für ataktische wie auch für isotaktische Konfigurationen stimmen die berechneten Werte von 〈r〉/nl2 gut mit den in der Literatur angegebenen Meßwerten überein. Die zur übereinstimmung mit den experimentellen Daten einzusetzenden Parameterwerte des Modells ändern sich in sinnvoller Weise mit der Länge der Seitenkette. Die experimentall ermittelten Temperaturkoeffizienten werden nur für ataktische Polypentene und Polybutene durch das FLORY‐Modell befriedigend beschrieben.
Über aziridinylchinone und ihre polymeren
Authors: Manecke Georg , Kretzschmar Hans‐Jürgen
Published: April 2003

Durch Addition von Aziridin an Mono‐ und Divinyl‐p‐chinone unterschiedlichen Redoxpotentials werden N‐substituierte Aziridinverbindungen dargestellt. Die Redoxpotentiale der Monomeren, ihr Polymerisationsverhalten und die Eigenschaften der Redoxpolymeren werden untersucht.
Polymérisation par ouverture de cycle, 1. Polymérisation du bicyclo[6.1.0] nonène‐4
Authors: Pinazzi Chr. P. , Cattiaux J. , Brosse J. C.
Published: April 2003

Le bicyclo[6. 1. 0]nonène‐4 soumis à l'action des catalyseurs de métathèse, conduit avec des rendements quantitatifs, à des polymères de masse moléculaire moyenne en nombre 5000. Les études spectroscopiques montrent que la structure des polymères correspond à celle d'un poly(butadiène‐1,4) dont une double liaison sur deux est remplacée par un cyclopropane. Une faible proportion de motifs de structure différente a été mise en évidence dans certains des polymères obtenus. L'étude systématique de la polymérisation du bicyclo [6. 1. 0] nonène‐4 en milieu cationique et en présence des complexes des métaux de transition, a permis de montrer que ces motifs correspondent à une polymérisation transannulaire qui apparait comme réction secondaire au cours de la polymérisation par métathèse.
Vinyl polymerization, 297. Polymerization of acrylonitrile initiated by the system of tetramethyl‐2‐tetrazene and pyruvic acid
Authors: Sugiyama Kazuo , Hatanaka Hideo , Nakaya Tadao , Imoto Minoru
Published: April 2003

The polymerization of acrylonitrile (AN) initiated by the system of 1,1,4,4‐tetramethyl‐2‐tetrazene (TMT) and pyruvic acid (PA) was investigated in dimethylformamide (DMF). The TMT/PA system could polymerize AN more easily than TMT alone. The polymerization was confirmed to proceed by a radical mechanism. The rate of polymerization was proportional to [TMT]0,52, [PA]0,59, and [AN]1,63. The over‐all energy of activation of the polymerization was found to be 7,7 kcal · mol−1 within the temperature range of 50 to 70,5°C. The reaction of TMT with PA in benzene gave products whose analysis corresponded to nitrogen, hydrogen, carbon dioxide, tetramethylhydrazine, and N,N‐dimethylacetamide. From these results and from the data of the ESR measurement of the TMT/PA system, a possible initiation mechanism is proposed.
A nuclear magnetic resonance study on the conformation and molecular interaction of polyelectrolyte model compound in alcohol/water mixtures
Authors: Miyamoto T. , Cantow H.‐J.
Published: April 2003

The conformation and molecular interaction of polyelectrolyte model compound (2,4‐dimethylglutaric acid) in alcohol/water mixtures were investigated by using high resolution NMR spectroscopy.

It is shown that the local conformation of meso‐isomer in alcohol/water mixtures slightly changes with the mole fraction of ethanol. The difference in the chemical shifts of two methylene protons and the chemical shift of carboxyl protons are comparably dependent of the mole fraction of ethanol. These results, however, do not always mean that the change in the viscosity of poly(acrylic acid) or poly(methacrylic acid) in alcohol/water mixtures is due to the change of such local conformation as estimated by NMR. On the contrary, it is probably true that such change in the viscosity curve is mainly due to the long‐range interaction between non‐adjacent segments.

It is also shown that the local conformation of meso‐isomer depends upon the use of the solvents, leading to the conclusion that its local conformation varies with the solvent.
Polymerisation of ethylene by catalysts formed from π‐ and σ‐bonded transition metal carbon compounds and silanols
Authors: Ballard D. G. H. , Heap N. , Kilbourn B. T. , Wyatt R. J.
Published: April 2003

Soluble halogen free polymerisation catalysts have been prepared by reacting tetrabenzyl zirconium and related compounds with silanols. The combination of tetrabenzyl zirconium and 1,1,3,3‐tetraphenyldisiloxane‐1,3‐diol (VI) was found to be particularly active. Structural analysis of VI shows that the SiOSi angle is linear, which may account for this compound behaving as a monodentate ligand. The relationship between structure and activity in these soluble systems and the transition metal polymerisation centres, prepared by reacting transition metal alkyls with silica and alumina, is discussed.
Cationic copolymerization of tetrahydrofuran with diketene. NMR analysis of copolymer microstructure
Authors: Okada Masahiko , Yokoyama Yasuaki , Sumitomo Hiroshi
Published: April 2003

Cationic copolymerization of tetrahydrofuran and diketene (4‐methylene‐2‐oxo‐oxetane) with triethyloxonium tetrafluoroborate as initiator was carried out and the microstructure of the products was investigated. The diad fractions determined by NMR analysis showed that both monomer units were distributed randomly along the copolymer chain, and that the propagating species of tetrahydrofuran added to both the carbon‐carbon double bond and the ring‐oxygen atom of diketene. The fraction of the former mode of addition was estimated to be 0,37–0,41, in notable contrast to the corresponding values observed in the copolymerization of 1,3‐dioxolane with diketene. The difference in the selective reactivities of the growing ions was discussed.
Eine blockierungsmethode zur darstellung molekular‐einheitlicher hydroxyphenylenmethylen‐verbindungen
Authors: Kämmerer Hermann , Rausch Werner , Söhle Ingrid
Published: April 2003

Hydroxyphenylenmethylen‐Verbindungen wurden nach verschiedenen Verfahren dargestellt. Dabei wurden folgende Ausgangsprodukte verwendet: p‐Kresol und Formaldehyd (Gl. (i)) oder p‐Kresol und 2,6‐Bis(hydroxymethyl)‐p‐kresol (4) (Gl. (ii)), (Duplikations‐Verfahren), 2‐Chlor‐6‐(3′‐chlormethyl‐2‐hydroxy‐5′‐methylbenzyl)‐p‐kresol (5) und 2‐Chlor‐p‐kresol (Gl. (iii)), (schrittweise Synthese) oder 2‐Chlor‐6‐chlormethyl‐p‐kresol (8) und p‐Kresol (Gl. (iv)) (Blockierungsmethode). Die nach den verschiedenen Methoden entstandenen Reaktionsprodukte wurden papierchromatographisch aufgetrennt und identifiziert unter Berücksichtigung der bei der Analyse auftretenden Nebenreaktionen.
Investigations on conformational transitions in polymer chains in dilute solution
Authors: Dondos Anastasios , Rempp Paul , Benoit Henri
Published: April 2003

Temperature dependence of light scattering and viscosity data was studied on three polymers: poly(4‐bromophenylethylene) [poly‐p‐bromostyrene], poly[1‐(methoxycarbonyl)‐1‐methylethylene] [poly(methyl methacrylate)] and poly(2‐pyridylethylene) [poly(vinylpyridine)] in dilute solution. It was observed that over a narrow range of temperature sharp changes of second virial coefficients, unperturbed dimensions and scattered intensities do occur. This phenomenon can be accounted for by assuming that in the chosen solvents the conformation of the chain undergoes changes, increasing temperature causing a higher flexibility.

These conformational changes disappear entirely on addition of minute amounts of well solvating, polar solvents, which confirms that the observed transition is only concerned with short range interactions along the chain.
Über den photochemischen abbau von polyurethanen
Authors: Schultze Hartmut
Published: April 2003

Einwirkung von Licht und Sauerstoff bei Raumtemperatur auf Polyurethane, die aus aromatischen Diisocyanaten und Diolen hergestellt wurden, führt zur Bildung von primären aromatischen Amino‐ und Hydroperoxy‐Gruppen. Oxidation der NH2‐Gruppen und Radikalreaktionen beim Zerfall der HOO‐Gruppen führen zur Verfärbung des Hochpolymeren. Die Bildung der NH2‐Gruppen und HOO‐Gruppen kann durch die Qualität der Ausgangs‐verbindungen, Reaktionsführung und geeignete Zusätze eingeschränkt werden. Diese Gruppen lassen sich durch Alkylierungsmittel bzw. Trioxo‐s‐triazin (Isocyanurat) abfangen. Polyurethane, die aus aliphatischen Diisocyanaten hergestellt wurden, unterliegen ebenfalls der Alterung.
Radical reactions initiated by chelate complexes of transition metals, 11. Effect of pyridine on the styrene polymerization initiated by the system bis[(—)‐ephedrine]copper(II) chelate/carbon tetrachloride
Authors: Bartoň Jaroslav. , Werner Peter , Vlčková Jana
Published: April 2003

The ability of the system bis[(—)‐ephedrine]copper(II) chelate (Cueph)/carbon tetrachloride/pyridine (Py) to initiate the styrene polymerization was studied. In the region near to an equal mole ratio [CCl4] : [Py] the rate of polymerization depends linearly on the concentration of pyridine. At a mole ratio [CCl4] < [Py] an inhibition period is observed which is inversely dependent on the concentration of CCl4. The rate of polymerization decreases with increasing inhibition period. On the basis of spectrophotometric investigations in the UV region the formation of an adduct of Cueph with Py is to be assumed. The effect of this adduct on the course of the styrene polymerization initiated by the system Cueph/CCl4/Py is discussed.
Zur kinetik der anionischen polymerisation von methyl‐methyacrylat in tetrahydrofuran bei −75°C
Authors: Löhr G. , Schulz G. V.
Published: April 2003

Die anionische Polymerisation von Methylmethacrylat (MMA) in Tetrahydrofuran (THF) verläuft bei −75°C mit Cumylcäsium bzw. oligomerem α‐Methylstyrylcäsium als Initiatoren ohne erkennbare Nebenreaktionen analog der anionischen Polymerisation von unpolaren Monomeren in ätherischen Lösungsmitteln. Als Beweis wird hauptsächlich die enge Molekulargewichtsverteilung der unter diesen Bedingungen hergestellten Polymethylmethacrylate angeführt.

Bei −75°C betragen die Geschwindigkeitskonstanten für die Monomeranlagerung an das Ionenpaar kw(±) = 80 dm3 mol−1 s−1 und an das freie Anion etwa kw(−) ≈︁ 6 · 104 dm3 mol−1 s−1. Leitfähigkeitsmessungen ergeben, daß die Dissoziationskonstante des Polymethylmethacrylcäsiums bei dieser Temperatur bei 10−9 mol dm−3 liegt.
Polymer modification and synthesis using sulphenyl derivatives, 1. Preparation of poly(ß‐chlorothioethers)
Authors: Cameron G. Gordon , Stachowiak Stephen A.
Published: April 2003

The preparation and characterization of some novel poly(ß‐chlorothioethers), from reaction of 4,4′‐biphenyldisulphenyl chloride (1) or benzene‐1,3‐disulphenyl chloride (2) with diolefins, are described.