bluuebunny/crossref_metadata_2025 huggingface dataset:
General interpretation of intrinsic viscosity – temperature data and application to solutions of polytetrahydrofuran
Authors: Evans J. M. , Huglin M. B. , Stepto R. F. T.
Published: April 2003

The general form of the variation of In [η] with temperature which results from the excluded‐volume theories of FLORY, KURATA‐STOCKMAYER‐ROIG, PTITSYN, and FIXMAN, is examined. On the basis of these theories a new analysis of ln [η]T versusT data is presented, which enables both d ln 〈r2〉0/dT and the Ψ‐temperature to be evaluated. The procedure has been applied to polytetrahydrofuran in a large number of solvents, and the applicability of excluded‐volume theories to these systems is discussed.
Synthesis and properties of poly[3.3‐bis(mercaptomethyl)oxetane]
Authors: Du Prez E. , Goethals E. J.
Published: April 2003

Several derivatives of 3.3‐bis(mercaptomethyl)oxetane (BMMO) have been synthesized and their polymerizations studied. Only those derivatives in which the sulfur atoms are substituted by an electron‐withdrawing group (acetate, carbonate, carboethoxy) gave polyethers under the influence of cationic catalysts such as boron trifluoride etherate or phosphorous pentafluoride. Polymers with a degree of polymerization up to 90 were obtained. By alkaline hydrolysis the polymers could be transformed into poly(BMMO). This polymercaptan was soluble only in alkaline medium (alcohol or water). It was oxidized to an insoluble polydisulfide by means of iodine. The rate of oxidation of poly(BMMO) dissolved in 0.5 N sodium hydroxide by means of oxygen in the presence of metal salts has been compared with the rate of oxidation of low molecular weight model compounds and poly(vinyl thiol). It was found that poly(BMMO) always reacted at the lowest rate whereas poly(vinyl thiol) reacted faster than the model compounds if the reaction was first order with respect to thiol concentration but slower if it was of zero order. The lower oxidation rate for the polymers is attributed to steric factors.
Stereospecific polymerization of asymmetric α‐olefins having different optical purity
Authors: Ciardelli F. , Montagnoli G. , Pini D. , Pieroni O. , Carlini C. , Benedetti E.
Published: April 2003

The polymerization of racemic and optically active α‐olefins having optical purity from 10 to 95% has been investigated by several ZIEGLER‐NATTA catalysts. Especially in the case of 3.7‐dimethyl‐1‐octene (I) the polymerization appears to be stereoselective, the predominant antipode being polymerized with higher specific rate. The stereoregularity of polymers from I and from 4‐methyl‐1‐hexene (II) slightly increases with monomer optical purity as shown by solvents extraction, IR spectra, and optical rotation; however a remarkable role is played by the catalytic system.

The distribution of R and S units in polymer fractions having different stereoregularity has been also investigated by polymerizing a mixture of (R)‐II and (S)‐II‐1‐14C and possible relationships between stereoregulation and stereoselectivity are discussed.

No particular effect of monomer asymmetric structure on polymerization stereochemistry has been observed in the case of 5‐methyl‐1‐heptene (III).
Polymérisations des acrylates de phényle et de p‐crésyle. Structures des polymères
Authors: Gueniffey H. , Pinazzi C. P.
Published: April 2003

Les acrylates de phényle et de p‐crésyle ont été polymérisés dans le toluène à −70°C et à +20°C avec le butyllithium comme amorceur, et dans le benzène à +80°C, par l'α.α′‐azodiisobutyronitrile. Les différents polymères ont été soumis à l'hydrolyse basique, estérifiés par CH2N2 en polyacrylates de méthyle, dont les structures ont été déterminées en RMN, puis comparées aux structures des polymères de départ. Les polyacrylates de phényle et de p‐crésyle ont été réduits avec LiAlH4, en alcools polyallyliques et ceux‐ci transformés en polyacétates par action de l'anhydride acétique.
Polymerisation of ethylene with soluble Ziegler‐natta catalysts
Authors: Höcker H. , Saeki K.
Published: April 2003

The polymerisation of ethylene was carried out in the presence of (C5H5)2TiCl2/(C2H5)2AlCl in benzene (I) and of TiCl4/(C2H5)AlCl2in chlorobenzene (II). In the initial state of the polymerisation with I oligomers with a narrow molecular weight distribution are formed. According to their IR and NMR spectra they were identified as predominantly saturated linear hydrocarbons. The effect of a substitution of the cyclopentadienyl rings by R = CH3and C2H5was studied as well as the influence of aging particularly on the molecular weight distribution. The catalytic system II yields predominantly unsaturated branched oligomers with broad molecular weight distribution. The ligand effect on the structure and on the molecular weight of the polymers obtained is discussed.
Radical terpolymerizations of acrylonitrile, vinyl sulfide and vinyl ether. Evaluation of reactivities of vinyl sulfide and vinyl ether toward polyacrylonitrile radical
Authors: Inoue Hiroshi , Otsu Takayuki
Published: April 2003

The co‐ and ter‐polymerizations involving acrylonitrile (M1), vinyl sulfide (M2) and vinyl ether (M3) were investigated to compare the difference in reactivities of vinyl sulfide and vinyl ether toward attack of polyacrylonitrile radical. From the independent copolymerization results for M1/M2 and M1/M3 systems, the reactivity ratio (k12/k13) was determined as 14.7 at 60°C. This ratio was also obtained, from the treatment of the terpolymerization data, as 8.93. On comparison of these values with the previous observation according to which there was a linear relationship between log (k12/k13) and the e values of the M1 monomers, corresponding to the attacking polymer radicals M1•, the values obtained from terpolymerization were found to fit better than those obtained from simple copolymerization. From the ARRHENIUS plot of log (k12/k13), the activation energy for the reaction of ethyl vinyl sulfide with polyacrylonitrile radical was found to be 2.9 kcal/mole lower than that of ethyl vinyl ether.
Vinyl polymerization 270. Polymerization of methyl methacrylate initiated by azibenzil
Authors: Nakaya Tadao , Tanaka Mamoru , Imoto Minoru
Published: April 2003

The polymerization of methyl methacrylate initiated by azibenzil (AB) was studied kinetically. The initial rate of polymerization (Rp) was found to be expressed by the equation Rp = k[AB]0.47[MMA]0.97. The polymerization proceeded through a radical mechanism. The overall activation energy for the polymerization was estimated as 16.1 kcal/mole. Furthermore, the rate of decomposition of AB was measured in benzene and the following rate equation was obtained: kd[sec−1] = 5.75·1010 exp(‐21.9 kcal/RT). From these results the initiation mechanism was discussed.
Zum einfluß der molekularen uneinheitlichkeit auf molekulargewichtsabhängige eigenschaften von polymeren in lösung
Authors: Sutter Wolfgang , Kuppel Adelbert
Published: April 2003

Die bei den verschiedenen Verfahren zur Bestimmung der ungestörten Dimensionen in der Literatur verwendeten Uneinheitlichkeitskorrekturen sowie die Beziehung zwischen Mw, MsD und M[η] werden unter Zugrundelegung der Verteilungsfunktion nach SCHULZ‐ZIMM neu berechnet.

Die neuen Werte unterscheiden sich von den bisher gebräuchlichen z.T. erheblich, was eine Neuinterpretation der davon betroffenen Literaturdaten nahelegt.
Untersuchungen zum reaktionsverlauf der kationisch initiierten, ringöffnenden copolymerisation von tetrahydrofuran und dicarbonsäureanhydriden
Authors: Öchsner Waldemar , Reichert Karl‐Heinz
Published: April 2003

Die kationisch initiierte Reaktion von Tetrahydrofuran (THF) mit Dicarbonsäureanhydriden führt unter ringöffnender Copolymerisation selbst bei Reaktionstemperaturen oberhalb der Ceilingtemperatur des Ringäthers zu Polyätherestern. Der Verlauf der einzelnen Reaktionsschritte der Copolymerisation und der Mechanismus der Wachstumsreaktion wurden durch kinetische Untersuchungen der Copolymerisationsreaktion THF/Bernsteinsäureanhydrid (BSA) sowie einer Modellreaktion THF/Essigsäureanhydrid (ESA) und durch Bestimmung der Zusammensetzung der Reaktionsprodukte ermittelt. Die kinetischen Versuche ergaben, daß der nukleophile Angriff von THF an ein Oxoniumion des Anhydrids die Geschwindigkeit der Wachstumsreaktion bestimmt und daß sich die Reaktivitäten der beiden Anhydrid‐Oxoniumionen gegenüber einem THF‐Angriff um einen Faktor von ca. 25 voneinander unterscheiden (…[−ESA]⊖ > …[−BSA]⊕). Aus der Zusammensetzung der Reaktionsprodukte oberhalb der Ceilingtemperatur von THF konnten die relativen Reaktivitäten der beiden Monomeren, THF und Anhydrid, in den konkurrierenden Anlagerungsschritten an das THF‐Oxoniumion …[−CO‐TH́F]⊕ ermittelt werden. Danach ist BSA um den Faktor 2 reaktiver als ESA.
Asymmetric addition catalyzed by optically active polymers. II.
Authors: Ohashi Shin'Ichi , Inoue Shohei
Published: April 2003

In the asymmetric addition of lauryl mercaptan to methacrylic esters and crotonic esters catalyzed by optically active amine, the optical yield of the products obtained by polymeric amine was higher than that by low molecular weight amines. The influence of the ester residue on the optical yield was remarkable in polymer catalyst system but not so remarkable in low molecular weight catalyst system. The influence of the ester residue on the reaction rate was not so remarkable. The specificity of the polymer catalyst was discussed referring to the reaction mechanism.
Polymerization of styrene by metal acetylacetonate/phenanthroline system
Authors: Kaeriyama Kyoji
Published: April 2003

Phenanthroline accelerates the polymerization of styrene by ß‐diketonate chelates of Mn(II), Mn(III), Fe(III), Cu(II), and Co(III), but has no appreciable effect on Ni(II). Phenanthroline retards the polymerization by acetylacetonate chelate of Co(II). The initiating radical is generated by a ligand exchange reaction of Mn tris‐acetylacetonate with o‐phenanthroline. The rate of polymerization is represented as
Rp ∝ [styrene] {[Mn(acac)3][phenanthroline]}1/2

The activation energy and frequency factor are 15.9 kcal/mole and 1.1·106 mole/1·sec in the presence of o‐phenanthroline. The values are compared with those without additives and in the presence of pyridine. Initiation mechanisms are proposed.
The kinetics and statistics of sequences during polymer analogous reaction as investigated by computer simulation
Authors: Klesper E. , Gronski W. , Barth V.
Published: April 2003

The behavior of sequences of monomer units during the polymer analogous reaction of a homopolymer to a copolymer is investigated with respect to its kinetics and statistics by simulation with a digital computer. Three basic reactions are presupposed with a reacting monomer unit in the chain being surrounded by none, one, or two already reacted units. The change in the probabilities of the monads, diads, triads, tetrads, and pentads with conversion, or with the number of random number events, is recorded in dependence of the probabilities for the three basic reactions. Sequence probabilities and reaction probabilities are discussed in terms of alternation and blockiness of the copolymers. The relation between the kinetics of the sequences obtained by simulation and by an actual polymer analogous reaction is determined. On an actual polymer analogous reaction the ratios of the reaction rate constants are found by fitting computer simulated curves for the triad probabilities to the experimental triad probabilities. The statistics of the sequences is shown to be non‐MARKOVian, in general. Conditional probabilities of different orders are calculated and compared with each other to find the lowest order necessary to calculate longer sequences with reasonable accuracy.
Über die Polymerisation des Isobutylens durch Aluminiumjodid in Anwesenheit einiger Alkylhalogenide
Authors: Lopour Petr , Pecka Jan , Marek Miroslav
Published: April 2003

Es wurde der Einfluß einiger n‐Alkylhalogenide (n‐Butylfluorid, n‐Butylchlorid und n‐Butylbromid) und einiger Benzylhalogenide (Benzylfluorid, Benzylchlorid und Benzylbromid) auf die durch Aluminiumjodid katalysierte Polymerisation des Isobutylens in Heptan studiert. Dabei wurde festgestellt, daß das n‐Butylfluorid und die Benzylhalogenide die Polymerisationsgeschwindigkeit wesentlich erhöhen. Aus der Abhängigkeit der Polymerisationsgeschwindigkeit und der Molekulargewichte der gewonnenen Polymeren von der Konzentration der Alkylhalogenide und des Aluminiumjodids geht hervor, daß die Alkylhalogenide nicht als Cokatalysatoren wirken, sondern daß die Erhöhung der Polymerisationsgeschwindigkeit durch katalytisch aktive Produkte verursacht wird, die durch Halogenaustausch zwischen dem Aluminiumjodid und den Alkylhalogeniden gebildet werden. Die Ergebnisse der vorliegenden Arbeit werden im Zusammenhang mit den Erkenntnissen diskutiert, die über die Polymerisation des Isobutylens mit den aus zwei FRIEDEL‐CRAFTS‐Halogeniden bestehenden Katalysatorsystemen gewonnen wurden.
Annealing behaviour of melt crystallised trans‐1.4‐polyisoprene
Authors: Martuscelli Ezio
Published: April 2003

The annealing behaviour of samples of melt crystallised trans‐1.4‐polyisoprene, containing different percentages of the two solid modifications, was examined. The plots of long‐spacings versus the annealing temperature show a discontinuity at a temperature that has been identified with the melting temperature of the low‐melting modification.

The equilibrium melting point Tm0 and the surface free energy σe of the crystallites of the low‐melting modification of trans‐1.4‐polyisoprene has been calculated thermodynamically using the slope method. A value of 78°C and 102 erg·cm−2 is found for Tm0 and σe, respectively.
Magnetic anisotropy effect on the chemical shift of linear hydrocarbons
Authors: Ando Isao , Nishioka Atsuo
Published: April 2003

Magnetic bond anisotropy effects on the chemical shifts of linear hydrocarbons were calculated for the terminal methyl and the methylene protons of planar zigzag chains with a number of carbon atoms from 3 to 22. It was found that the methylene protons near the chain end appear at a slightly higher field than these at the middle of the chain, and approach an asymptotic value at lower carbon numbers comparing with those of the middle point. It may be proposed that the tendencies of the observed chemical shifts of some linear hydrocarbons in α‐chloronaphthalene may be interpreted by the existence of some extended conformations of the chains in this solvent.
Production of organometallic polymers by the interfacial technique. XXI. A study of some associated reaction variables in the synthesis of poly[imino‐1.4‐phenyleneimino(dibutylstannylene)]
Authors: Carraher Charles E. , Winter Duane O.
Published: April 2003

Polymers of the below form are synthesized via the interfacial polycondensation route.
magnified image

A study has been made of the influence of the nature of the solvents employed and base and reactant concentration. New interfacial solvent systems are presented.
The stabilisation of critically branched polycondensates
Authors: Kálal J. , Gordon M. , Devoy C.
Published: April 2003

The critically branched state of matter (i.e. systems near their gel point), which occupies a central role in biology, is usually observed only fleetingly in synthetic polymers. Well characterised polycondensates of decamethylene glycol (DMG)/benzene 1.3.5‐triacetic acid (BTA) have now been stabilised near gelation by quantitative benzhydrylation of the free carboxyls with diphenyl diazomethane. Such a polymer system, of weight av. mol. wt. about 105 was so stable that it remained unchanged after heating in air to 150°C for two hrs. The bulk viscosity of such liquids is studied as a function of temp. in relation to the WLF transform. The manner in which the isoviscous‐state theory of Tg fails is elucidated. The crystallisation of about two per cent residual DMG causes a sharp a sharp reversible gelation in these liquids, probably because of some sort of interaction between the liquid polycondensate and the crystal surfaces. The tribenzhydryl ester of BTA is a new crystalline compound of mol. wt. about 750.
The alkaline hydrolysis of methyl methacrylate/isoprene copolymers. 1. Influence of copolymer composition on the hydrolysis behaviour
Authors: Bevington J. C. , Ebdon J. R.
Published: April 2003

Methyl methacrylate/isoprene copolymers are hydrolysed in an alkaline medium to different degrees depending upon their compositions. The limiting degrees of hydrolysis can be correlated with the calculated distributions of sequences in the copolymers. A small amount of exchange of methoxy groups between methanol and the copolymer accompanies hydrolysis.
The alkaline hydrolysis of methyl methacrylate/isoprene copolymers. 3. Direct detection of the hydrolysed units
Authors: Bevington J. C. , Ebdon J. R. , Mallard D. J. H.
Published: April 2003

Bromination of methyl methacrylate/isoprene copolymers leads to the formation of γ‐lactone rings between adjacent methacrylate and isoprene units. The limiting degrees of hydrolysis of the methacrylate units in the brominated copolymers are less than those in the untreated samples. This, together with other evidence, provides support for the conclusions about the hydrolysis reached in Part 1.
Die polykondensationsprodukte des phloroglucins mit hexamethylendiamin
Authors: Tokarzewski Ludomir , Pietranek Waclaw
Published: April 2003

Bei der Polykondensation von Phloroglucin und Hexamethylendiamin in Toluol‐ oder Wasserlösung bildet sich unlösliches, dunkelgrün gefärbtes Harz. Es wurden die mechanischen und einige elektrische Eigenschaften untersucht und die Struktur des Harzes ermittelt.
Investigation on branching of polyvinylchloride
Authors: Rigo A. , Palma G. , Talamini G.
Published: April 2003

An investigation was carried out on branching of polymers obtained by lauroyl‐peroxide or by radiation‐initiated polymerization of vinylchloride. As a result, branching shows no dependence on conversion and could be ascribed, at least partially, to the presence of CH2Cl‐side groups.

A reaction mechanism for this type of branching was proposed.
Studies on formaldehyde‐condensation resins. XV. Gelation theory for phenolic resins
Authors: Uragami Tadashi , Oiwa Masayoshi
Published: April 2003

The gelation of phenol with formaldehyde was investigated theoretically in terms of addition‐condensation reactions; the theoretical kinetic equations involving the relations between the extents of reaction of each functional group and the rate constants, the expression for the gel point etc. were derived by considering the distribution of the structural units.

The ratio of the rate constant for condensation to that for addition is evaluated by applying a theoretical kinetic equation to the experimental measurements. The ratio of the rate constant for addition of para position of phenolic nucleus to that of ortho position is also determined by combining the kinetic equation, stoichiometric relation, and expression for the gel point. The total yield of resin, the yield of sol, and the number‐average molecular weight of the sol fraction are discussed in some detail.
Molecular fractionation during crystallization and its application to the study of lamellar thickening during isothermal crystallization
Authors: Mehta Aspy , Wunderlich Bernhard
Published: April 2003

The increase of average lamellar thickness of polymer crystals occurring during isothermal crystallization has been ascribed by KAWAI, HOSOI, and KAMIDE1 to the phenomenon of molecular fractionation induced by crystallization. This explanation however, is not in agreement with several experimental observations. These observations are discussed and compared with an earlier explanation proposing fractionation during crystallization followed by crystal thickening.
Umsetzung von benzoesäureglycidylester mit primären und sekundären aminen in alkohol als lösungsmittel
Authors: Fiala Vladimír , Lidařík Miloslav
Published: April 2003

Die Umsetzung von Benzoesäureglycidylester mit aliphatischen, aromatischen und heterocyclischen primären und sekundären Aminen in Gegenwart von Isobutylalkohol wurde studiert. Die Reaktion der Glycidylverbindungen mit Aminen verläuft nach einem termolekularen Mechanismus. In Alkohol als Lösungsmittel wird ein pseudobimolekularer Reaktionsverlauf ermittelt. Die basische Dissoziationskonstante des Amins kann zur Bestimmung der approximativen Geschwindigkeitskonstante der Benzoesäureglycidylester‐Amin‐Reaktion verwendet werden. Eine größere Abweichung von der Abhängigkeit zwischen der Dissoziationskonstante des Amins und der Geschwindigkeitskonstante der Umsetzung wurde beim Benzylamin gefunden. Die Aktivierungsenergie für die Reaktion von Benzoesäureglycidylester mit Aminen wurde bestimmt.
Crystallization of ethylene/vinylacetate random copolymers
Authors: Okui Norimasa , Kawai Toru
Published: April 2003

It may be anticipated that uncrystallizable units, if introduced randomely into a crystallizable polymer chain, might strongly prohibit the chain folding and enhance intermolecular crystallization, which will give rise to the fringed micelle structure. In anticipation of this, crystallization and resultant texture were studied for random copolymers of ethylene (E) and vinyl acetate (VAc) as functions of composition and crystallization temperature. Crystallization was carried out isothermally from solution as well as from melt. DTA melting behavior of the melt‐crystallized samples revealed that two types of crystals with different melting temperatures were formed during the isothermal crystallization of the copolymers. Since the height of the peak appearing at the higher temperature T1 decreased and that at the lower temperature T2 increased with the increasing VAc content and crystallization temperature, the former peak may be assigned to the chain folded crystals and the latter to the bundle‐like crystals. In other words, the transition from the chain folding crystallization to the bundle‐like crystallization did not occur sharply at a given composition as expected but the two types of crystallization coexist in a rather wide range of compositions, depending on the crystallization temperature.

It became also apparent that molecular fractionation occurred during the isothermal crystallization with respect to the composition of the copolymer. Electron microscopy could not confirm the existence of the bundle‐like crystals, probably due to the fact that the individual bundle‐like crystal was not large enough to be distinguished from much larger chain‐folded lamellae with more definite shapes. On the other hand, solution grown crystals gave a single melting peak and a single X‐ray long spacing, suggesting only the chain folding crystallization occurred in the whole range of compositions studied. Molecular fractionation was again evident and the material left uncrystallized in the solution increased with the VAc content. These results may imply that the intermolecular bundle‐like crystallization depends strongly on the probability of finding other chain molecules around a given molecule. The X‐ray crystallinity as well as the heat of fusion measured suggest that the thickness of the amorphous surface layer (loose loops) of the solution grown crystals increases with the VAc content.
Rare gas plasma polymerization of benzene at −196°C
Authors: Hollahan John R.
Published: April 2003

Benzene has been polymerized in the solid state at −196°C by a radiofrequency plasma of helium. The resulting polymer shows no sign of aromaticity. Infrared spectra suggest the polymer is a branched, aliphatic hydrocarbon polymer with some unsaturation and crosslinking. The formation of the polymer is best explained by the cission of a bond in the benzene molecule with the formation of the 1.3.5‐hexatriene biradical which polymerizes.
Molecular characterization of polyacrylonitrile polymerized by gamma‐ray irradiation
Authors: Kamide Kenji , Terakawa Toshikazu
Published: April 2003

Polyacrylonitrile prepared by gamma‐ray irradiation to urea‐canal complex of acrylonitrile (U‐PAN) was fractionated from a solution in dimethylsulfoxide (DMSO) at 25°C, using toluene as a precipitant. Viscosities of fractions, thus prepared, in DMSO and in ethylenecarbonate (EC), were measured for elucidating the unperturbed‐chain dimensions together with the long‐range polymer/solvent interaction parameter. In conclusion, U‐PAN which is comparatively isotactic has almost the same value (the K value is 2.95·10−3) of the unperturbed‐chain dimensions as the atactic polyacrylonitrile prepared by conventional, radical polymerization (R‐PAN), whilst the long‐range parameter of U‐PAN is extremely smaller than R‐PAN in a poor solvent. The conclusions reached from these experimental facts are in very good consistence with those of other polymers with less difference in the stereoregularity.
Light scattering of polymethylmethacrylate solutions in binary solvent mixtures. Part 2. In acetone/benzene mixtures
Authors: Fujishige Shoei , Elias Hans‐Georg
Published: April 2003

An isotactic and an atactic polymethylmethacrylate have been investigated by light scattering measurements at 25°C in acetone/benzene mixtures in order to see the effects of the difference in the microstructures between the two stereoisomers on the preferential solvation and some other molecular parameters of the polymers. The extreme differences due to the structural effects between the stereoregular and the stereoirregular polymers appear in the mixed solvents with higher content of acetone.
Untersuchung der von anionen‐radikalen aromatischer kohlenwasserstoffe initiierten methylmethacrylat‐polymerisation mit hilfe der infrarotspektroskopie
Authors: Panayotov I. M. , Rashkov I. B. , Berlinova I. V.
Published: April 2003

Die von Anionen‐Radikalen der aromatischen Kohlenwasserstoffe Biphenyl, Naphthalin, 2‐Phenylnaphthalin, Phenanthren, Anthracen und Acenaphthalin initierte Methylmethacrylat‐Polymerisation wurde mit Hilfe der IR‐Spektroskopie untersucht. Aus den IR‐Spektren der Reaktionsgemische sowie aus den UV‐Spektren der Polymeren wurden Schlußfolgerungen über den Initiierungsmechanismus gezogen.
Etude du mécanisme des polymérisations amorcées par les métaux alcalino‐terreux. II. Etude de la copolymérisation du styrène et du méthacrylate de méthyle
Authors: Mathis Claude , François Bernard
Published: April 2003

Dans cet article nous présentons différents résultats qui concernent la copolymérisation du styrène et du méthacrylate de méthyle amorcée par le calcium, le strontium et le baryum en milieu polaire et non polaire. Nous avons déterminé la composition des produits formés en fonction de la composition initiale des monomères et du taux de conversion. En milieu polaire le copolymère formé au début de la copolymérisation est riche en styrène. Nous avons par ailleurs mis en évidence la formation de copolymères séquencés dont l'une des séquences est constituée par du polyméthacrylate de méthyle et l'autre par un enchaǐnement statistique de styrène et de méthacrylate de méthyle. Les séquences de polyméthacrylate de méthyle présentent un nombre de triades isotactiques plus élevé qu'un homopolymère préparé dans les měmes conditions expérimentales. Ces résultats permettent de conclure à l'existence simultanée d'un mécanisme de type anionique et d'un mécanisme de type radicalaire lors de la polymérisation du méthacrylate de méthyle et de sa copolymérisation avec le styrène en présence des métaux alcalino‐terreux.
Synthèse et caractérisation de copolymères séquencés polyoxyéthylène/poly‐ε‐caprolactone
Authors: Perret Rémi , Skoulios Antoine
Published: April 2003

On a montré que les fonctions terminales d'un polyoxyéthylèneglycol disodé sont capables d'amorcer la polyaddition de l'ε‐caprolactone. On a préparé de cette manière une série de copolymères triséquencés poly‐ε‐caprolactone/polyoxyéthylène/poly‐ε‐caprolactone, comportant des séquences de longueur variée.

Les échantillons ont été fractionnés à 34°C par addition progressive d'isooctane à leur solution dans le benzène. Les différentes fractions ont été caractérisées par osmométrie, tonométrie, dosage chimique des extrémités des chaǐnes macromoléculaires, résonance magnétique nucléaire et analyse chimique élémentaire.

On a montré que les copolymères synthétisés contenaient au départ des quantités appréciables de poly‐ε‐caprolactone homopolymère de masse moléculaire peu élevée, mais qu'il était facile de les en débarrasser par simple précipitation fractionnée.
Syntheses and reactions of ferrocene‐containing polymers. V. Polymerization of ethinylferrocene
Authors: Nakashima Toshihide , Kunitake Toyoki , Aso Chuji
Published: April 2003

Polymerizations of ethinylferrocene were carried out with ZIEGLER‐type catalysts. AlR3‐TiCl4 catalysts gave predominantly cyclic trimers, i.e., 1.2.4‐ and 1.3.5‐triferrocenylbenzene, and AlR3‐Ti(OBu)4 catalysts gave linear polymers of comparatively low molecular weight (1000‐3500). Basic organic additives like pyridine or triethylamine showed limited influence on the yield and the product distribution. The polyene may contain some irregular structures. On the other hand, polyethinylferrocene obtained by dehydrative condensation of acetylferrocene was shown by NMR spectroscopy to contain considerable amounts of aliphatic hydrogen.
Radical reactions initiated by chelate complexes of transition metals. VII. Effect of some copper chelates on the decomposition of cumene hydroperoxide in benzene
Authors: Bartoň J. , Horanská V.
Published: April 2003

The kinetics of cumene hydroperoxide (CHP) decomposition in benzene in the presence of bis‐(‐)‐ephedrine copper(II) chelate (Cueph), copper acetylacetonate (Cuac), and copper oxinate (Cuox) was studied by chemical analysis, UV, and ESR measurements. It was found that only Cueph markedly accelerated the CHP decomposition. The course of the CHP decomposition in presence of Cueph may be described by the kinetic equation for bimolecular reactions. From the temperature dependence an activation energy of 17.3 kcal· mole−1 for CHP decomposition has been calculated. For the decay of paramagnetic Cu2⊕ particles concentration during CHP decomposition in the presence of Cueph a reaction order of 1.1 with respect to [CHP] and 0.35 order kinetics for [Cueph] as well as an activation energy of 13.2 kcal·mole−1 were established. It was found on the basis of UV spectroscopy that during CHP decomposition in the presence of Cueph a complex between CHP and Cueph as an intermediate product was formed. Thus for the equilibrium constant of complex formation a value of 32 1 · mole−1 was estimated. The kinetic results obtained have been explained on the basis of supposition that a regeneration cycle for cupric species is operative. The disagreement between the supposed existence of the regeneration cycle and the observed decay of paramagnetic Cu2⊕ particles in the course of CHP decomposition in the presence of Cueph is the discussed.
Molecular weight distribution of “living” polymers generated by a bifunctional initiator
Authors: Höcker Hartwig
Published: April 2003

Different rates of initiation and propagation, e.g., in the case of living polymerization, lead to considerable deviations from a POISSON distribution. Using a bifunctional initiator the distribution obtained is composed of a single distribution and a coupled distribution. The maximum value of x̄w/x̄n never exceeds 1.4 even for a ratio kp/ki = 106.
Untersuchungen von ordnungszuständen in DNA‐Lösungen mit hilfe der lichtstreuung
Authors: Gruber Erich , Gruber Rosl , Schurz Josef
Published: April 2003

Aus der Winkelabhängigkeit der Lichtstreuung von salzhaltigen DNA‐Lösungen kann auf das Vorliegen von Fernordnungen in der Lösung geschlossen werden. Diese Ordnung bildet sich in den ruhenden Lösungen im Verlauf mehrerer Stunden bis Tage aus. Sie kann durch Rühren gestört werden und verschwindet in der Nähe der Schmelztemperatur der DNA.

Aus den gemessenen Extremwerten der Streufunktion läßt sich formal ein BRAGGscher Wert von 6000 Å errechnen, aber auch Periodizitäten von 2000 Å bzw. 3300 Å sind möglich. Zwischen 1 · 10−4 bis 3 · 10−4 g/ml läßt sich keine eindeutige Abhängigkeit von der Konzentration feststellen, wodurch man hier ein einfaches Parallelstranggitter ausschließen kann. Unmittelbar nach der Filtration durch Flächenfilter der Porenweite 0,5 μm zeigen die DNA‐Moleküle stark gestörte, knäuelartige Struktur.
Lithium based coordination catalysts for the hydrogenation of diene and vinylaromatic polymers
Authors: Falk John Carl
Published: April 2003

A new method is described to hydrogenate polymeric unsaturation. The hydrogenation of polybutadiene, polyisoprene and polystyrene is effected with coordination catalysts derived from alkyl or aryl lithiums and transition metal salts of 2‐ethylhexanoic acid. The catalyst activity is discussed as a function of lithium‐transition metal ratio, catalyst concentration, temperature, and hydrogen pressure.
Photopolymerization of methyl methacrylate induced by trithiocyanatotripyridine iron(III) complex
Authors: Sakota Naokazu , Takahashi Kazunobu , Nishihara Koji
Published: April 2003

The photopolymerization of methyl methacrylate (MMA) in the presence of trithiocyanatotripyridine iron(III) complex (Fe(SCN)3Py3) was kinetically studied. The overall rate of photopolymerization (Rp) in ethanol at 35°C was shown as following:

The obtained value of kp/k was satisfactorily consistent with those reported for the radical polymerization of MMA hitherto. The overall activation energy of the polymerization was calculated to be 3.0 kcal/mole, and the value of Ep − 1/2 Et obtained from the log kp/k versus l/T curve was 3.1 kcal/mole.

These kinetic data and the composition curve of the copolymerization of MMA and styrene showed that the photopolymerization with the iron(III) complex proceeded via a free radical mechanism and that the monomer participated in the initiation step.
Estimation of chemical inversions of monomer placement in polypropylene by pyrolysis gas chromatography
Authors: Seno Hiroshi , Tsuge Shin , Takeuchi Tsugio
Published: April 2003

A unique method of estimating the amount of chemical inversions in monomer placement of isotactic and atactic polypropylene was developed by means of pyrolysis gas chromatography of its chlorination products. The molar proportion of mesitylene/pseudocumene was determined from the chromatograms of the pyrolysis products. The isomers of trimethylbenzene which are formed during the pyrolysis gave good information about the triads in the original polypropylene.
Sedimentation of dissolved macromolecules in the terrestrial gravitational field near the critical locus
Authors: Wolf B. A.
Published: April 2003

The present paper demonstrates theoretically as well as experimentally, that the gravitational field of the earth produces very pronounced changes in the equilibrium concentration of dissolved macromolecules with height, under near critical conditions.

Thus it could be observed for the system polystyrene/cyclohexane that the equilibrium concentration at the bottom of a tube is approximately three times that at a height of 10 cm, under such conditions. In the case of polymolecular samples the sedimentation is associated with a corresponding fractionation.
Die spektroskopische untersuchung einer cyclischen, tetrameren verbindung aus p‐kresol und formaldehyd
Authors: Kämmerer Hermann , Happel Günter , Caesar Friedrich
Published: April 2003

In Anlehnung an den Syntheseweg von HAYES und HUNTER wurde eine cyclische, tetramere Verbindung (VII) über eine linear 4‐Kernverbindung (VI) (aus p‐Kresol und Formaldehyd) hergestellt. Ihre Struktur wurde spektroskopisch untersucht. Mittels UV‐ und IR‐Spektren läßt sich VII von der Ausgangsstufe VI und einem Konkurrenzprodukt VIII unterscheiden. Die H‐NMR‐Spektren der Ringverbindung und ihrer Ausgangsverbindung (VI) stimmen vollständig mit den angegebenen Strukturformeln überein; sie geben, bei 20 und 60°C aufgenommen, Hinweise auf bestimmte Konformere der Ringverbindung. Das massenspektrometrisch bestimmte Molekulargewicht (480) stimmt mit dem berechneten (480,6) überein.
Polymerization mechanism of N‐carboxy‐α‐amino acid anhydride by organometallic compounds. IV. Stereospecific association of diisobutylaluminum 4‐methyloxazolidonate as a model compound of intermediate of the polymerization
Authors: Makino Tetsuya , Inoue Shohei , Tsuruta Teiji
Published: April 2003

In the copolymerization of D‐ and L‐alanine N‐carboxy anhydride (NCA) with an excess of L‐antipode by triethylaluminum, a polyalanine containing an equal amount of L‐ and D‐residues was obtained in the early stage of the polymerization.

Initiation of the polymerization was the hydrogen abstraction from NH group of the NCA by the trialkylaluminum.

Since sarcosine NCA (N‐methylglycine NCA) was not polymerized with trialkylaluminum, alanine NCA is considered to be polymerized through the form of the metalated NCA. A stereochemical study on diisobutylaluminum 4‐methyloxazolidonate (BAO) as a model compound of the metalated NCA showed that BAO was associated with each other forming preferentially a meso‐dimeric structure. From this result, the metalated NCA is also considered to form preferentially a meso‐dimeric structure in conformity with the observed fact that the NCA polymerization produced in the early stage the polyalanine consisting of practically the same amount of L‐ and D‐residues.
Beitrag zur Auswertung der Molekulargewichtsverteilung von Polypropylen
Authors: Pechočová Marie , Pechoč Vladimír
Published: April 2003

Durch Auswerten von Fraktionierdaten verschiedener Polypropylene und Polypropylenfasern wurde festgestellt, daß die untersuchten, handelsüblichen Polymeren eine logarithmische Normalverteilung der Molekulargewichte nach WESSLAU, die schwach abgebauten Polymeren eine korrigierte logarithmische Normalverteilung nach DAVIS, TOBIAS und PETERLI und die stark abgebauten Polymeren eine exponentielle Verteilung nach TUNG aufweisen.
Poly(1.4‐phenylen‐1.1‐diphenyläthylen) durch WURTZ‐synthese
Authors: Braun D. , Platzek U.
Published: April 2003

Durch Reduktion von Diphenyl‐(4‐carboxy‐phenyl)‐methanol mit LiAlH4 gelangt man zum Diphenyl‐(4‐hydroxymethyl‐phenyl)‐methanol, das mit Thionylchlorid in Diphenyl‐(4‐chlormethyl‐phenyl)‐methylchlorid übergeführt wird. Die WURTZ‐Synthese mit Natrium in Toluol ergibt Poly(1.4‐phenylen‐1.1‐diphenyläthylen) mit einem Molekulargewicht Mn = 2030 (P̄n = 8). Der Polymerisationsgrad wird durch Bildung monofunktioneller Verbindungen wie Diphenyl‐(4‐chlormethyl‐phenyl)‐methan und durch die Spaltung der Polymerketten mit Natrium beeinflußt.
Photodegradation behavior of some vinyl ketone copolymers
Authors: Kato Masao , Yoneshige Yasuo
Published: April 2003

Photodegradation behavior for copolymers of styrene (St), α‐methyl styrene (α‐MSt) and methyl methacrylate (MMA) with methyl vinyl ketone (MVK) and phenyl vinyl ketone (PVK) in the presence of air was investigated in the solid state and in solution.

Photolysis of St/MVK and St/PVK copolymers proceeded smoothly and an increase of the ketone in the copolymer resulted in an increase of the rate of degradation. Generally, the rate of degradation is faster in St/PVK copolymers than in St/MVK copolymers. It is likely that the degradation of the copolymers takes place mainly through NORRISH type II reaction.

It was found that the photolysis of α‐MSt/PVK copolymers was retarded considerably as compared with St/PVK copolymers.

An unexpected behavior was observed in the case of MMA/MVK or MMA/PVK copolymers. These copolymers were expected to degrade with slow rates; they degraded, however, rapidly. Some experiments were done to explain this phenomenon.
Heterophases in block‐copolymer/solvent systems in the liquid and in the solid state
Authors: Sadron Charles , Gallot Bernard
Published: April 2003

A general review of the observed isothermal phase diagram (structure as a function of the concentration) of a number of (A–B)/S systems is given where A–B is a linear blockcopolymer containing the long sequences A and B and S is a preferential solvent for one of the sequences.

Special attention is devoted to the third region of the diagram (large concentration of A–B) where periodic and regular (mesomorphic) structures are observed.

The effect of the concentration on the structure (cubic, hexagonal and lamellar) and on the values of the structural parameters as they are observed by X‐ray diffraction or electron micrography is discussed.

It is shown that the type of structure of a given A–B copolymer in a given solvent S is determined mainly by the ratio of the volumes of the phase containing the insoluble sequence and the volume of the phase formed by the solution, a fact which can be considered as a generalization of a law given by G. E. MOLAU.
Cyclopolymérisation du diméthacrylate de dihydroxy‐2,2′‐diméthyl‐5,5′‐diphénylméthane
Authors: Guéniffey Henri , Kämmerer Hermann , Pinazzi Christian
Published: April 2003

La cyclopolymérisation du diméthacrylate de dihydroxy‐2,2′‐diméthyl‐5,5′‐diphénylméthane (II) a été réalisée en milieu benzène à 80° avec l'azobisisobutyronitrile comme amorceur, en milieu toluène à −500°C avec le butyllithium comme amorceur et en tétrahydrofuranne (THF) avec le naphthalène sodium. Les polymères obtenus ont été soumis à l'hydrolyse basique, les polyacides résultants traités par le diazométhane donnent les polyméthacrylates de méthyle correspondants dont la tacticité a été étudiée en NMR (100 MHz). La réduction des polymè;res a été effectuées par LiAlH4 en milieu THF. Des alcools polyméthylallyliques ont été isolés. Les résultats semblent montrer l'influence de la matrice II sur le degré de tacticitt du polyrnéthacrylate de méthyle.
Solvent effects on stereoregularity of poly(vinyl trifluoroacetate) obtained by radical polymerization
Authors: Matsuzawa Shuji , Yamaura Kazuo , Noguchi Hiroji , Hayashi Hiromichi
Published: April 2003

Vinyl trifluoroacetate was polymerized by free radicals in various kinds of solvents at temperatures between +60 and ‐40°C. The syndiotactic and isotactic diad contents of the polymer were determined via the triad content, which was obtained by their NMR‐spectra.

The differences of the activation enthalpies and those of the activation entropies between isotactic and syndiotactic arrangements were calculated from the temperature dependence of the ratio of isotactic to syndiotactic diads formed in the different solvents. A compensation effect exists between the two differences. The syndiotacticities of the polymers synthesized in alkanes in which the polymers were insoluble were higher than those in esters and ketones in which the polymers were soluble.

The syndiotactic diad contents of the polymer synthesized in alkanes and ketones at −40°C amount to 60∼63% and 52∼56% respectively.
Zur copolymerisation von α‐methylstyrol und butadien III. Das NMR‐spektrum der sequenzen mit zentraler α‐methylstyroleinheit
Authors: Elgert K. F. , Seiler E. , Puschendorf G. , Cantow H.‐J.
Published: April 2003

Die 220‐MHz‐Protonenresonanzspektren von Copolymeren aus α‐Methylstyrol und Butadien werden untersucht. Die Modellsubstanzen stellt man in einer durch Lithiumbutyl initiierten Copolymerisation bei −75°C in Tetrahydrofuran dar. Das NMR‐Spektrum der Phenyl‐ und α‐Methylgruppe wird durch die Signale konfigurativer Triaden und Triaden mit zentraler α‐Methylstyroleinheit erklärt. Die chemische Verschiebung der Triaden mit zentraler α‐Methylstyroleinheit erfolgt im α‐Methyl‐Bereich soweit zu niedrigerem Feld, daß keine starke Überlappung mit den Signalen der konfigurativen Triaden auftritt. Im Bereich der Phenylprotonen sind konfigurative Triaden und Triaden mit zentraler α‐Methylstyroleinheit überlagert. Bei Verwendung von 3,4,5‐Trideutero‐α‐methylstyrol ist es möglich, die Zuordnung von konfigurativen Triaden und Triaden mit zentraler α‐Methylstyroleinheit im Spektrum der ortho‐Phenylprotonen zu treffen.
Caractérisation de réactions primaires de dégradation oxydante au cours de l'autoxydation des polyoxyéthylènes à 25°C: Étude en solution aqueuse avee amorçage par radiolyse du solvant. II. Arguments pour un mécanisme monomoléculaire de décomposition des radicaux peroxyles
Authors: Crouzet Claude , Marchal Jean
Published: April 2003

Des coupures statistiques sans période d'induction sont observées au cours de I'autoxydation du polyoxyéthylène étudiée dans l'eau 1 25°C et à l'abri de la lumikre. L'homolyse des hydroperoxydes formés sur le polymère ne peut pas expliquer les coupures car elle est trop lente dans ces conditions. La décornposition de radicaux alcoxyles secondaires produits par la réaction bimoltculaire non terminante des radicaux peroxyles formts sur le polymère ne fournit pas non plus l'explication de ces coupures. En effet, pour que les cinttiques théorique et expérimentale de production des coupures soient en bon accord, il faudrait, contrairement aux propriétés connues des radicaux peroxyles secondaires, que la réaction bimoléculaire de terminaison des radicaux peroxyles soit négligeable par rapport à leur réaction bimoléculaire non terminante. Un mode de décomposition des radicaux peroxyles selon un mécanisme monomoléculaire restant à définir doit donc être responsable de la dégradation oxydante ainsi caractérisée.
Zur kinetik der radikalischen fällungspolymerisation von methyacrylonitril in substanz unter anfangsbedingungen
Authors: Engel F.
Published: April 2003

Die durch AIBN initiierte Polymerisation von Methacrylonitril wurde bei 50–75°C in Substanz untersucht. Die Reaktionsordnung ist in bezug auf die Initiatorkonzentration 1/2. Die Bruttoaktivierungsenergie beträgt 22,9 kcal . mol−1. Wird K2w/ka (Kw = Wachstumskonstante, ka = Abbruchskonstante) aus dem Zahlenmittel des Polymerisationsgradaes (P̄n) und der Bruttogeschwindigkeit zur Zeit t = 0 (vbr,0) bestimmt, darf bei Polymeren mit bimodaler Molekulargewichtsverteilung nur der kurzkettige Anteil berücksichtigt werden. Für 60°C wird unter Anfangsbedingungen k2w/ka = 1,75.10−5 dm3.mol−1. s−1 und der Radikalausbeutefaktor f = 0,58 gefunden. Die kinetischen Konstanten unterscheiden sich nicht von denen der Lösungspolymerisation.
The addition halogenation of polyalkenamers. IV. X‐ray structures of the crystalline chain segments of chlorinated cis‐ and trans‐1,4‐polybutadienes
Authors: Bassi I. W. , Scordamaglia R.
Published: April 2003

The addition chlorination products of trans‐1,4‐polybutadiene and cis‐1,4‐polybutadiene are slightly crystalline. The interpretation of the X‐ray fibre patterns has shown that the crystalline segments obtained from trans‐1,4‐polybutadiene are diisotactic poly(erythro‐1,2‐dichloro butamer) while the crystalline segments obtained from cis‐1,4‐polybutadiene are disyndiotactic poly(threo‐1,2‐dichloro butamer).
Recherche de polymères «Absorbeurs UV». Synthèse et polymérisation de nouveaux monomères du type vinyl‐4 benzophénone méthoxylée
Authors: Pinazzi Chr. P. , Fernandez A.
Published: April 2003

Les p‐vinyl benzophénones méthoxylées ont été synthétisées par action du chlorure de p‐vinyl phényl magnésium sur les benzaldéhydes méthoxylés suivie de l'oxydation des p‐vinyl benzhydrols obtenus. Les monoméres ont été polymérisés par procédure radicalaire en solution. Cette réaction conduit, dans le cas de la benzophénone diméthoxylée, à des polyméres de grandes masses. Ces polymères seront partiellement déméthoxylés dans un prochain travail afin de faire apparaître les propriétés d'absorbeurs UV.
Thermodynamic parameters of the helix → coil transition of poly(L‐tyrosine) in mixed organic solvents
Authors: Quadrifoglio Franco , Giancotti Vincenzo , Crescenzi Vittorio
Published: April 2003

The helix → coil transition of poly(L‐tyrosine) in dimethylsulfoxide/trimethylphosphate and in dimethylsulfoxide/dimethylformamide solution, induced by either changing the solvent composition (at 25°C) or by changing the temperature was studied calorimetrically (heat of dilution experiments) and by means of optical activity measurements, respectively. The calorimetric enthalpy of transition, in particular, and the VAN'T HOFF heat of transition of poly(L‐tyrosine) at 25°C resulted, dependent upon the mixed solvent considered. As a consequence, the σ parameter of the theory of ZIMM and BRAGG appeared solvent dependent in the case studied by us.