bluuebunny/crossref_metadata_2025 huggingface dataset:
Studies on maleate/fumarate isomerisation in unsaturated polyesters by infrared spectroscopy
Authors: Gupta S. K. , Thampy R. T.
Published: April 2003

For study of maleate/fumarate isomerisation in unsaturated polyesters infrared technique was used without using model compounds. This was done by solving the following equation for two different polyesters or one polyester with two concentrations for the molar extinction coefficients at 675 cm−1 for maleate and 980 cm−1 for fumarate.

equation image

Percentages of maleate and fumarate are given by following equations:

equation image

The out of plane vibration of CH for maleate appeared at slightly lower frequency, i.e. at 675 cm−1 due to steric hindrance. It was noted that the increase of the ratio of maleate to saturated acid in the polyester enhances the conversion from maleate to fumarate due to coiling tendency of the chain and causing steric compression. This tendency was also shown by phthalic anhydride based polyesters due to ortho carboxylic group compared with adipic acid and isophthalic acid. It is evident from more conversion from maleate to fumarate in case of phthalic anhydride based polyesters than that of isophthalic acid and adipic acid based polyesters.

In case of bisphenol‐A based polyesters, low conversion from maleate to fumarate took place, because of less coiling of between the two segments of the chain which are phenyl groups associated through carboxyl group of maleate. Conversion was more pronounced in polyesters based on 2.2‐di‐(4‐hydroxy‐3.5‐dibromophenyl) propane and 2.2‐di‐(4‐hydroxy‐3.5‐dichlorophenyl)‐propane due to steric hindrance. An alternative explanation for more conversion from maleate to fumarate in case of halogenated bisphenol based polyesters may be due to catalysing effect of the small amount of halogen evolved during polycondensation. Similarly in chlorendic acid (1.4.5.6.7.7‐hexachloro‐5‐norbornene‐2.3‐dicarboxylic acid) based polyesters, the isomerisation from maleate to fumarate increases as the chlorendic acid content in the polyester increases. In this case catalysing effect of chlorine evolved during polycondensation may be more effective because dissociation of halogen from non‐aromatic system is easier than from aromatic system.
Determination of reactivity ratios for the copolymerisation of vinyl acetate with methyl acrylate by proton magnetic resonance spectroscopy
Authors: Kulkarni N. G. , Krishnamurti N. , Chatterjee P. C. , Sivasamban M. A.
Published: April 2003

Reactivity ratios for the copolymerisation of vinyl acetate with methyl acrylate have been determined in bulk at 60°C for conversions smaller than 1% using proton magnetic resonance spectroscopy. The values (rma = 6.3 ± 0.4; rva = 0.031 ± 0.006) thus obtained were compared with the values obtained by other workers using different analytical techniques. The present method appears to be extremely simple and accurate.
Polythiolester. I. Polythioglykolid
Authors: Elias Von Hans‐Georg , Bührer Heinrich G.
Published: April 2003

Thioglykolsäure‐S‐carbonsäureanhydrid wurde mit primären, sekundären oder tertiären Aminen, Natriummethylat, Wasser oder Natriumborhydrid als Initiatoren in Substanz oder in Tetrahydrofuran oder Dioxan gelöst bei Temperaturen zwischen −50 und +200°C zu Produkten mit Gewichtsmitteln Mw des Molekulargewichtes kleiner als 36000 g/mol Molekül und Schmelzpunkten von maximal 160°C polymerisiert. p‐Bromanilin, Thioglykolsäure und Borfluoridätherat initiierten die Polymerisation nicht. Nur Dichloressigsäure und Hexafluoraceton‐Sesquihydrat erwiesen sich als nichtabbauende Lösungsmittel. Säureamide und tertiäre Amine bauen die Polymeren ab. Der Polymerisationsmechanismus wird diskutiert. Die Polykondensation von Thioglykolsäure in Substanz führt unter Bildung ven Dithioglykolid als Nebenprodukt nur zu niedrigen Molekulargewichten. Thioglykolsäuremethylester zeigt mit verschiedenen Umesterungskatalysatoren etwa die gleiche Polykondensationsgeschwindigkeit wie Thioglykolsäure. Die Viskositäts‐Molekulargewichts‐Beziehung ergibt sich für Messungen in Dichloressigsäure bei 25°C im Molekulargewichtsbereich Mw = 5500 bis 36000 zu [η] = 0,018M ml/g.
Étude de la cristallisation des polymères. VI. Structure des mélanges binaires de polyoxyéthylènes de faible masse moléculaire
Authors: Gilg Par B. , Skoulios A.
Published: April 2003

On énumère quelques modèles de structure susceptibles d'illustrer les arrangements possibles des chaînes macromoléculaires dans des mélanges cristallins de deux fractions monodispersées d'un polymère de faible masse moléculaire. On décrit ensuite les résultats d'une étude expérimentale d'une série de mélanges binaires de polyoxyéthylèneglycol.

On montre que, dans tous les cas considérés dans ce travail, les chaînes macromoléculaires se séparent suivant leurs longueurs respectives et se localisent dans des feuillets distincts. Selon le système examiné, ces feuillets sont empilés les uns sur les autres soit d'une manière chaotique, soit alors dans des domaines plurilamellaires (des quasi‐phases) distincts.
Étude par diffusion de la lumière et viscosité du système ternaire: Polyoxyéthylène/tétrachlorure de carbone/méthanol
Authors: Moldovan Par L. , Strazielle Cl.
Published: April 2003

Nous avons étudié par diffusion de la lumière et viscosité le comportement d'un polyoxyéthylène de faible masse moléculaire en solution dans le mélange tétrachlorure de carbone/méthanol.

Nous observons une adsorption préférentielle du tétrachlorure de carbone par le polymère dans tout le domaine de composition étudié. De plus, la viscosité intrinsèque [η] dans les mélanges est supérieure à celle que nous observons dans les solvants purs et passe par un maximum pour le mélange à 75%.

Nous avons essayé d'interpréter ces résultats en fonction des propriétés thermodynamiques du système ternaire.
Bulk and solution polymerization of vinyl‐monomers in the presence of a chain transfer agent. Part II. Acrylonitrile
Authors: Vidotto G. , Brugnaro S. , Talamini G.
Published: April 2003

The polymerization of acrylonitrile at 50°C in bulk as well as in the presence of ethylene carbonate as a solvent has been investigated to determine the effect of carbon tetrabromide on the reaction. In bulk polymerization the autocatalysis and the initial polymerization rate exhibit a maximum as a function of CBr4 concentration. When the polymerization is carried out in ethylene carbonate, carbon tetrabromide affects the rate of the reaction as well as the molecular weights of the products. From the molecular weights of polyacrylonitrile samples obtained from polymerization in homogeneous medium a transfer constant to carbon tetrabromide of 4 · 10−2 has been deduced. The kinetic features of the reaction occurring in heterogeneous medium and the variations in rate and molecular weight of the products connected with the passage of the reaction system from homogeneity to heterogeneity, are interpreted according to a kinetic picture recently suggested by the authors.
The catalytic activity of the poly‐L‐lysine‐copper(II) complex on the oxidation of 3.4‐dihydroxyphenylalanine
Authors: Hatano Masahiro , Nozawa Tsunenori , Ikeda Sakuji , Yamamoto Takakazu
Published: April 2003

The poly‐L‐lysine‐ (PLL) and poly‐DL‐lysine‐copper(II) complexes were used as the catalysts for the oxidation of 3.4‐dihydroxyphenylalanine. The catalytic activity of poly‐L‐lysine‐copper(II) complex (PLL‐Cu(II)) was found to be larger than that of bis(ethylenediamine)‐copper(II) at both pH 6.9 and 10.5. The catalytic activity was discussed on the basis of some kinetic data. The oxidation was presumed to proceed through the formation of a reaction intermediate between the catalyst and the substrate. It was also revealed that the oxidation was catalyzed asymmetrically when the PLL‐Cu(II) was used as the catalyst at pH over 10.5. The asymmetric oxidation was presumed to be ascribed to the helical structure of PLL‐Cu(II) in the aqueous solution of pH 10.5.
Discussion on the mechanism of alternating copolymerization of styrene and maleic anhydride
Authors: Tsuchida Eishun , Tomono Tsugikazu
Published: April 2003

To clear up the detailed mechanism of the alternating copolymerization of styrene (St) and maleic anhydride (MAn) concerning the initiation species, the propagation species, the tendency of the chain transfer reaction as well as the directional tendency of the reaction between copolymer radicals and monomer complexes, the role of the charge transfer complexes, characterization of end groups and additional donor effects were examined.

The equilibrium constant of the St/MAn (1 : 1) complex was determined to be 0.31 by NMR spectroscopy, that suggested considerable amounts of complexes existing in the system. As expected, a small quantity of initiator (14C‐azobisisobutyronitrile (AIBN)) was incorporated into the St/MAn copolymer. Chlorine atoms were scarcely incorporated into the copolymer synthesized in CCl4 with AIBN or benzoyl peroxide (BPO) as an initiator. Hence the copolymerization was considered to be induced only by attacke of initiator radicals to the monomer or the complexes, contrary to the usual conception of telomerization.

When the electron donor monomer was added to the system, the terpolymerization could be treated as a copolymerization of the two complexes, i.e., St/MAn and Donor/MAn. By adding naphthalene the rate maximum point shifted from higher concentration of MAn to the equivalent concentration of St and MAn. Degradative chain transfer to N.N‐dimethylaniline was observed, confirming the existance of poly‐MAn radicals. It was suggested from these results that the charge transfer complex and uncomplexed MAn took part in the copolymerization of St and MAn. This was proved kinetically. The whole mechanism was discussed.
Dégradation oxydante du polystyrène à 25°C. II. Étude du mécanisme par amorçage radiochimique en solution chloroformique diluée
Authors: Abadie Par Marc , Marchal Jean
Published: April 2003

À 25°C, la peroxydation du polystyrène est accompagnée d'une dégradation oxydante mise en évidence par la fragmentation des macromolécules sans période d'induction mesurable.

L'étude cinétique de cette dégradation a été faite en amorçant les réactions d'oxydation du polymère par irradiation γ (60Co) de ses solutions dans le chloroforme. L'analyse des produits légers par chromatographie en phase gazeuse et la détermination de la cinétique de formation des coupures au hasard par viscosimétrie ont été réalisées simultanément sur les solutions irradiées.

L'hypothèse de la production d'une molécule de styrène lors de la formation de chaque coupure, coupure qui résulterait de la décomposition monomoléculaire de radicaux peroxyles secondaires selon un mécanisme avec état de transition hexagonal, permet de rendre compte des résultats.
The mechanism of the gamma‐ray polymerization of vinyl chloride in bulk. I. Dependence of the degree of polymerization on temperature and conversion
Authors: Russo Saverio , Stannett Vivian
Published: April 2003

The radiation‐induced polymerization kinetics of vinyl chloride in heterogeneous conditions (bulk) has been extensively studied and compared with the chemically‐initiated reaction in bulk and in solution. The main role of monomer chain transfer on the degree of polymerization has been confirmed and the rate constant values CM for homogeneous and heterogeneous conditions have been compared. It has been proved that the heterogeneity of the polymerizing system does not affect the value of CM.

In the very last stages of polymerization the polymer formed presents lower molecular weights, higher long‐chain branching, and larger poly‐dispersity. An interpretation of these results has been proposed.
The mechanism of the gamma‐ray polymerization of vinyl chloride in bulk. II. Polymerization rates and kinetic approaches
Authors: Russo Saverio , Stannett Vivian
Published: April 2003

A study of the occluded and long‐living macroradicals in the radiation‐induced polymerization of vinyl chloride in bulk has been carried out by using the ESR method and the post‐polymerization reaction. Our results show only minor contributions from these species to the polymerization rates. Furthermore, the dose‐rate dependence of the polymerization rate is close to 0.50, in agreement with a bimolecular termination. The ensemble of our results strongly suggests a steady‐state approach to the polymerization kinetics of vinyl chloride. The scheme proposed by TALAMINI et al. [Makromolekulare Chem. 117 (1968) 140] has been adopted and extended to a radiation‐induced polymerization.
An investigation on the mechanism of homogeneous cationic polymerization of methyl vinyl ether by NMR spectroscopy
Authors: Matsuzaki Kei , Sakota Kazuyuki
Published: April 2003

Methyl vinyl ether‐α.β‐d2 was synthesized and polymerized with BF3·OEt2 or stannic chloride‐trichloroacetic acid as catalyst at −78 up to 0°C in toluene or methylene chloride. The NMR spectra of the polymers were determined on nitromethane solutions and the triad tacticity was obtained from the methoxyl absorptions. Pentad resonances were observed on chlorobenzene solutions. Tetrad resonances were assigned from the methylene proton absorptions in the deuterium‐decoupled spectra, assuming that the polymerization proceeded according to the first‐order MARKOVIAN trial. It was found that the proportions of the two meso methylene protons were nearly equal irrespective of polymerization conditions and the mode of double bond opening was discussed.
Solubility parameter and hydrocarbon sorption of low density polyethylene
Authors: Ghosh S. K.
Published: April 2003

A new and quick method, namely, the gaschromatographic technique, has been used to determine the solubility parameter of polyethylene. The calculated quantities of sorption of various pure components in polymer bears a logarithmic relationship to the experimental values.
The cationic polymerization of 1‐isopropylidene‐dicyclopentadiene
Authors: Cesca S. , Priola A. , De Chirico A. , Santi G.
Published: April 2003

1‐Isopropylidene‐dicyclopentadiene (III) has been homopolymerized by means of different cationic catalysts (BF3·OEt2, TiCl4, aluminum ethyl halides) to give amorphous polymers of high mol. wt., generally above 50,000. No oily oligomers or insoluble polymers were obtained under mild conditions.

UV, IR, and NMR analysis showed that the repeating unit of the polymer arises from 1.4 opening of the conjugated diene system and that it contains two double bonds. Pyrolysis results support the proposed structure.

The high value (0.74) of the exponent of the KUHN‐MARK‐HOUWINK equation indicates that the polymer is linear. The polydispersity index, deduced from the integral mol. wt. distribution function, was 1.64. The molecular dimensions in solution were determined by the STOCKMAYER‐FIXMAN and KURATA‐STOCKMAYER treatments. The characteristic constant K⊖ (5.5·10−4) and the parameter C∞ of the polymer were compared with those of other linear polymers.

The cationic copolymerization of III with 1‐isopropylidene‐3a.4.7.7a‐tetrahydroindene (I) gave: r(I) = 1.05 ± 0.6 and r(III) = 2.29 ± 0.68.
Leiterpolymere aus Poly‐(isopropenylmethylketon)
Authors: Kador Ulrich , Mehnert Peter
Published: April 2003

Aus Poly‐(isopropenylmethylketon) wurden bei 300°C Leiterpolymere hergestellt, deren Bildungsreaktion und Struktur untersucht wurde. Mit Hilfe der NMR‐Spektroskopie gelang es, Ringbildungen entlang der Polymerkette direkt nachzuweisen. Der Umsatz der Ringbildungsreaktion konnte aus den NMR‐Spektren bestimmt werden. Weiterhin konnten der Anteil der Einzelringe und der Anteil höher konjugierter Ringsysteme quantitativ ermittelt werden. Der zeitliche Verlauf der Reaktion legt nahe, daß die Kondensationsreaktion statistisch abläuft. Die Bildung höher konjugierter Ringsysteme ist eine Folgereaktion.
Die mit Natriumphenolat katalysierte Addition von Äthylenoxid und Propylenoxid aus ihren Gemischen an Monophenylmonoalkylenglykole. III. Der Druckeinfluß auf die Äthylenoxid‐ und Propylenoxid‐Addition an Monophenylmonoäthylenglykol
Authors: Staude Eberhard
Published: April 2003

Werden Äthylenoxid und Propylenoxid aus Gemischen beider Substanzen mit Natriumphenolat als Katalysator an Monophenylmonoäthylenglykol addiert, dann nimmt das Produkt der Reaktivitätsparameter mit steigendem Druck bis 1000 atm höhere Werte an. Daraus wird auf eine bevorzugte Äthylenoxidreaktion geschlossen. Das Aktivierungsvolumen der reinen Äthylenoxidaddition wird zu −38 ml/Mol bestimmt.
Zur Autoxydation von Polystyrol
Authors: Dulog Lothar , David Karl‐Heinz
Published: April 2003

Die mit Azoisobuttersäuredinitril (AIBN) initiierte Autoxydation von Polystyrol (PS) in Chlorbenzol bei 60°C ist von der Ordnung 0,75, bezogen auf AIBN, und 0,34, bezogen auf PS. Der niedrige Exponent der Polystyrolkonzentration weist neben intermolekularen Wachstumsschritten auf intramolekulare Reaktionsschritte bei der Autoxydation hin.

Die bei der Autoxydation am Polystyrol gebildeten Hydroperoxidgruppen zerfallen in Essigsäthylester als Lösungsmittel mit einer Aktivierungsenthalpie von 19,7 kcal/Mol und einer Aktivierungsentropie von −29 cal/Mol Grad. Das spricht für einen monomolekularen bifunktionellen Zerfallsmechanismus.

Als flüchtige Produkte bei diesem Hydroperoxidzerfall werden Phenol, Benzaldehyd und Acetophenon gebildet. IR‐Spektren von oxydiertem Polystyrol zeigen Banden wie Modellverbindungen mit Hydroperoxidgruppen in 1.3‐Stellung.
Association phenomena of PMMA in solutions and gels
Authors: Borchard Werner , Pyrlik Manfred , Rehage Günther
Published: April 2003

Stereocomplex formation of isotactic and syndiotactic polymethylmethacrylate (PMMA) could be demonstrated using X‐ray, NMR, and viscosity techniques. In this paper it is shown by measurements of viscosity and investigation of swelling properties that the association of isotactic and syndiotactic sequences of the polymer occurs as well in the solutions and gels of atactic PMMA. From the temperature dependence of the reduced specific viscosity and the swelling it can be deduced that association causes network formation due to microcrystalline regions which have a melting point range. In solutions of toluene with mixtures of isotactic and syndiotactic PMMA an intermolecular association, with atactic PMMA an intramolecular association is discussed. In chloroform no association could be observed.
Discussion on the mechanism of polymerization of α‐olefins with Ziegler‐Natta catalysts
Authors: Allegra G.
Published: April 2003

A monometallic mechanism of monomer complexation and addition to the growing chain for the isotactic polymerization of an α‐olefin in the presence of α‐, γ‐ or δ‐TiCl3 is proposed, which avoids the back‐jump of the Ti‐R bond required by the COSSEE‐ARLMAN mechanism. The overall activation energy for propagation involved in the latter mechanism should be higher than that allowed by the mechanism proposed here, which may be more easily reconciled with the figure found for polypropylene (∼ 5 kcal/mole). The steric requirement for a Ti atom on the side surface of a crystal to be catalytically active is that monomer complexation must be possible on both the Ti valencies pointing outside: this requires the active site to be slightly protruding above the two neighbouring layers. Each active site is intrinsically chiral; the cis‐opening of the double bond is in agreement with the mechanism.
Calculation of molecular weights in emulsion polymerization systems
Authors: Watterson John Grant , Parts Adolf Gustav
Published: April 2003

Calculations of the polymer molecular weight distribution are carried out using a model of emulsion polymerization, which fundamentally derives from the early work of HARKINS, and which, in its general features, is to‐day accepted. The distributions are actually presented as functions of the kinetic chain lifetime and time of reaction, although, under certain assumptions set out in the following work, the lifetime is directly proportional to the molecular weight.
Fluoreszenzspektroskopische Untersuchungen an Polyacenaphthylen und Copolymeren aus Styrol und Acenaphthylen
Authors: Schneider F. , Springer J.
Published: April 2003

Polyacenaphthylen zeigt sowohl im Festzustand als auch in Lösung bei Raumtemperatur eine Excimerenfluoreszenz, die bei Copolymeren aus Acenaphthylen und Styrol nicht auftritt. Bei diesen Copolymeren erfolgt eine Wanderung der Anregungsenergie von den Styrol‐ zu den Acenaphthylenbausteinen, so daß bei Raumtemperatur selbst aus festen Copolymeren mit geringem Acenaphthylengehalt bei Anregung der Styrolbausteine nur die Fluoreszenz der Acenaphthylenbausteine emittiert wird. In 2‐Methyltetrahydrofuran‐Lösungen bei 77 und 298°K wird der Wanderungseffekt ebenfalls, jedoch wesentlich schwächer, beobachtet. Die Mechanismen der Energieübertragung werden diskutiert.
Polymères thermostables. XII. Les poly‐benzothiazin‐1.4‐ones‐2 et leur transformation en polybenzothiazoles
Authors: Rabilloud Guy , Sillion Bernard , De Gaudemaris Gabriel
Published: April 2003

On a étudié la condensation de la dithio‐3.3′ benzidine sur les acides arylènediglyoxyliques ou leurs esters, soit dans des solvants organiques, soit dans l'acide polyphosphorique. Dans le premier cas, on obtient des prépolymères contenant des cycles benzothiazoline qui, à température élevée, donnent des polybenzothiazoles. Dans le second cas, on prépare de nouveaux polymères hétérocycliques: les poly‐benzothiazin‐1.4‐ones‐2, qui se transforment en polybenzothiazoles par un traitement thermique à 400°C. Ces différentes transformations ont été étudiées sur des composés modèles préparés à partir de l'o‐aminothiophénol et de l'acide phénylglyoxylique ou son ester de méthyle.
Syntheses and reactions of functional polymers. LVIII. Polymerization of N‐vinyl‐2‐oxazolidone in the presence of polymethacrylic acid
Authors: Endo Takeshi , Numazawa Ryozo , Okawara Makoto
Published: April 2003

The polymerization of N‐vinyl‐2‐oxazolidone (NVOx) in the presence of polymethacrylic acid (PMAA) was studied and the following results were obtained: (1) NVOx decomposed to 2‐oxazolidone and acetaldehyde in acidic aqueous solution (pH < 4.0) and the rate of decomposition increased as the acidity increased in this pH range. (2) The radical polymerization of NVOx was carried out at pH 4.0 and the rate equation,

was obtained. (3) The rate increased in the presence of PMAA and attained maximum at 1:1 molar ratio of NVOx to PMAA. The activation energies and frequency factors in the presence and absence of PMAA were estimated. (4) The rate decreased as pH increased and was constant above pH 5.0, but was independent of ionic strength.
Die Übertragungsreaktion von polychloropren‐ und polyvinylacetat‐radikalen mit 14C‐markierten niedermolekularen modellen der polychloroprenkette
Authors: Bezděk Milan , Exner Josef , Kříž Jaroslav , Hrabák František
Published: April 2003

Es wurden niedermolekulare, mit 14C markierte Modeller der Polychloroprenkette dargestellt und in ihrer Gegenwart die homogene Polymerisation von Chloropren und Vinylacetat bei 50°C durchgeführt. Als Modelle für die aktiven Radikale aus dem Initiator dienten Polyvinylacetatradikale. Aus der Beziehung zwischen dem Zahlenmittel des Polymerisationsgrades des Polymeren und dem molaren Verhältnis des Modells und des Monomeren wurden die relativen Übertragungskonstanten der Modelle in beiden Monomeren bestimmt. Aus der gemessenen Radioaktivität der Polymeren wurde die Gesamtmenge der Modellverbindung bestimmt, die sowohl durch Übertragung als auch durch Addition der polymeren Radikale in die Polymerkette eingebaut wird. Aus den Daten wurden die individuellen Geschwindigkeitskonstanten der Übertragung und der Addition der Polyvinylacetat‐ und der Polychloroprenradikale durch die beiden Modelle berechnet und die Anteile der Reaktion der Polychloroprenradikale und der Radikale aus dem Initiator an der Bildung der Wachstumszentren am Polymeren bewertet.
Über die elektrische leitfähigkeit oligomerer und polymerer 2.5‐Dimethoxyphenylen‐vinylene
Authors: Manecke G. , Zerpner D. , Kossmehl G.
Published: April 2003

Die bereits beschriebenen oligomeren und polymeren 2.5‐Dimethoxyphenylen‐vinylene1 wurden im Bereich von Raumtemperatur bis etwa 120°C auf ihre elektrische Leitfähigkeit untersucht. Die Werte für σ298°K erreichen maximal 2,0Ω10−6·−1·cm−11 bei einer Aktivierungsenergie von 0,34 eV. Gegenüber den 1.4−1verknüpften Verbindungen zeigen die entsprechenden mit 1.3‐Verknüpfung eine geringere elektrische Leitfähigkeit. Die 2.5‐Dimethoxysubstitution der Phenyleneinheiten bewirkt eine erhebliche Leitfähigkeitssteigerung im Vergleich zu den unsubstituierten Phenylen‐vinylenen.
Einfluß der quellung in aceton auf das kernresonanzspektrum von polyäthylenterephthalat
Authors: Eichhoff U. , Zachmann H. G.
Published: April 2003

Die Kernresonanzspektren isotherm kristallisierter Proben von Polyäthylenterephthalat wurden vor und nach der Quellung in deuteriertem Aceton als Funktion der Temperatur gemessen. Anschließend wurde jedes Spektrum in eine breite und eine schmale Komponente zerlegt. Es zeigt sich, daß durch die Quellung der Einfrierbereich verbreitert und die Einfriertemperatur erniedrigt wird. Diese Erniedrigung ist von den Kristallisationsbedingungen unabhängig. Die Linienbreite der schmalen Komponente wird durch die Quellung leicht erhöht, was für eine Zunahme der Kettenverspannung in den nichtkristallinen Bereichen spricht. Das zweite Moment der breiten Komponente wird durch die Quellung erniedrigt. Daraus wird geschlossen, daß das Quellmittel auch in die Kristallite eindringt.

Des weiteren wurde eine Probe unmittelbar durch Quellung kristallisiert. Bei dieser Probe beobachtet man eine besonders kleine Linienbreite der schmalen Komponente. Dies wird durch den höheren Quellmittelgehalt der Probe sowie durch eine relativ geringe Verspannung der Ketten in den nichtkristallinen Bereichen erklärt. Beides ist eine Folge des besonderen Mechanismus der Quellungskristallisation.
Influence de la température et de la nature du solvant sur les dimensions du poly‐p‐bromostyrène. Observation d'une transition conformationnelle
Authors: Karayannidis Petros , Dondos Anastasios
Published: April 2003

We have investigated the dilute solution properties of poly‐p‐bromostyrene, in a number of solvents, at temperatures ranging from 15 to 70°C. It was found that the unperturbed dimensions of this polymer are depending upon the nature of the solvent, as it was already observed for several polar polymers. The largest values of K⊖were found in solvents tightly associated with the polymer chain, increasing thus the chain stiffnes.

Poly‐p‐bromostyrene exhibits in benzene and in dioxane around 20°C a conformational transition which affects the unperturbed dimensions. This transition brings with it a rapid increase of the chain flexibility, as it could be shown from measurements of limiting viscosity number and of light‐scattering.

Around 50°C in the same solvents, another transition was observed, which is affected by the solvent‐polymer (long range) interactions.

Addition of a solvent (as DMF) able to give rise to specific interactions with the polar groups of the polymer chain inhibits all these transition phenomena.

It is however difficult to claim that the two observed transition phenomena are really distinct. It may well be that in a rather broad temperature range only one transition affecting both short and long range interactions takes place.
Rheological properties of poly‐α‐olefin melts
Authors: Shirayama Kenzo , Matsuda Tadashi , Kita Shin‐Ichiro
Published: April 2003

In order to investigate the influence of the side‐chain‐length on the melt viscoelasticity of the hydrocarbon polymers, dynamic viscosity η′, dynamic rigidity G′ and apparent viscosity ηa of a series of six different poly‐α‐olefins have been measured with a rotating cylinder‐type rheometer.

The molecular weight dependence of η′ and ηa was relatively greater at lower shear rate. At fixed shear rate and temperature, η′, G′, and ηa for each polymer sample were expressed by the form of KM. The values of K decreased with increasing side‐chain length and the values of α were approximately 3–4 for all the samples studied.

η′ vs. ω G′ vs. ω and ηa vs. γ curves at different temp. (130–230°C) could be superposed according to the usual time‐temperature superposition method, and the shift factors aT obtained from η′, G′, and ηa were practically the same.

The flow activation energies obtained from aT first increased with increasing side‐chain length in going from polyethylene to polyhexene‐1, and thereafter decreased in going from polyhexene‐1 to polyoctadecene‐1. They were all lower than that of high pressure polyethylene.

These results appear to support the idea that the branching structure of high pressure polyethylene is much more complicated than the side‐chain structure of poly‐α‐olefins.
Über die aktivität von katalysatorgemischen aus metallorganischen verbindungen und thalliumtrichlorid bei der trioxanpolymerisation
Authors: Glavčev I. , Kabaivanov V. , Natov M. , Šperov I.
Published: April 2003

Die Untersuchung der katalytischen Aktivität von Gemischen aus unterschiedlichen metallorganischen Verbindungen und Thalliumchlorid bei der Trioxanpolymerisation ergab, daß sie vom Ionencharakter bzw. von der Art der metallorganischen Verbindung abhängig ist. Die aktivsten Katalysatorgemische bilden sich aus Thalliumchlorid und organischen Verbindungen von Magnesium und Aluminium mit 22–34% Ionencharakter. Beim Vermengen von Thalliumtrichlorid mit metallorganischen Verbindungen bilden sich Komplexe mit dem unbeständigen Tl3⊕, deren Konzentration zeitlich abnimmt. Am schnellsten vollzieht sich die Konzentrationsabnahme von Tl3⊕ in den katalytisch aktivsten Gemischen. Untersucht wurde ferner der Einfluß des Wassergehalts im Monomeren auf den Polymerisationsvorgang.
The polymerisation of propylene oxide by organomagnesium compounds
Authors: Stafford J. W.
Published: April 2003

Diethyl magnesium as a diethyl etherate‐dioxanate complex polymerises propylene oxide in a diethyl ether solution to very high molecular weight crystalline polymer. Magnesium dibromide diethyl etherate polymerises propylene oxide in diethyl ether to low polymer. Ethyl magnesium bromide diethyl etherate polymerises propylene oxide in diethyl ether in four distinct kinetic stages. In the first two kinetic stages, polymer similar to that produced by diethyl magnesium is obtained in very low yield. Polymer of Mv ≈ 10,000 to 15,000 in yields up to 50% is produced in the next two stages. Above a certain catalyst concentration, the second stage is characterised by gel formation and precipitation. The third kinetic stage, during which most of the eventual polymer yield is produced, occurs with breakdown of the gel and redissolution of the precipitate, a similarity with polymerisation of propylene oxide by magnesium dibromide. With the ethyl magnesium bromide polymerisation, above the aforementioned catalyst concentration, change of catalyst concentration or solvent affects only the initial polymerisation stage kinetically.
Synthese und chemische Eigenschaften einiger Copolymerisate von 8‐Hydroxy‐5‐vinyl‐chinolin‐Derivaten. 2. Teil: Amphotere Kationenaustauscher
Authors: Manecke Georg , Aurich Hans‐Peter
Published: April 2003

5‐Vinyl‐8‐benzyloxy‐chinolin bzw. ‐chinaldin wurden mit Divinylbenzol copolymerisiert. Die vernetzten Produkte wurden mit verdünnter Salzsäure entbenzyliert. Durch polymeranaloge Bromierung wurde ein Teil der Harze modifiziert. Die Aufnahmefähigkeit der Harze für Cu2⊕‐, Ni2⊕‐ und Zn2⊕‐Ionen wurde untersucht, und die hohe Austauschkapazität für diese Ionen wird diskutiert.
L'isocaoutchouc. Etude des paramètres de cyclisation et d'isomérisation
Authors: Pinazzi C. P. , Brossas J. , Clouet G.
Published: April 2003

Cette étude présente une nouvelle préparation du méthylènecyclobutane qui permet d'obtenir avec une grande pureté ce monomère. La polymérisation du méthylènecyclobutane suivant un processus de Ziegler‐Natta ternaire y est étudiée en détail, ce qui a permis de mettre en évidence que le polymère à double liaison exo passait par le stade endo avant de se cycliser. Enfin, nous avons commencé une modification chimique de l'isocaoutchouc et notamment une ozonisation qui a donné une polycétone linéaire.
Influence of the stereoselectivity of the polymerization process on the optical activity of isotactic copolymers of enantiomeric α‐olefines
Authors: Bonsignori Osvaldo , Luisi Pier Luigi , Suter Ulrich
Published: April 2003

The molar optical activity [Φ]D of isotactic copolymers of enantiomeric α‐olefins as a function of the monomer optical purity P has been calculated for a particular kinetic model of stereoselectivity. According to this model, the catalyst is considered a racemic mixture of dissymmetric enantiomeric catalytic centers, able to discriminate between the two enantiomeric comonomers.

The calculations have been performed for copolymers of (S)‐ and (R)‐4‐methyl‐1‐hexene and of (S)‐ and (R)‐3.4‐dimethyl‐1‐pentene. The stereoselectivity has been related to the auxiliary parameter c, defined as the ratio between the two rate constants which determine the insertion of (R) and (S) monomers to the catalytic centers. The patterns of [Φ]D versus P calculated for different c values are rather close one to the other in the region of low stereoselectivity (c > 0.6). These results confirm that optical activity is not very sensitive to the features of the stereoselectivity of the copolymerization process. It is pointed out, however, that more useful information could be obtained from the study of the temperature coefficient of optical activity, particularly if more suitable polymeric structures are chosen.
Physical properties of poly‐1‐methyloctamer, a model of the ethylene/propylene copolymer
Authors: Gianotti G. , Dall'asta G. , Valvassori A. , Zamboni V.
Published: April 2003

Investigation of ethylene/propylene random copolymers of constant overall composition has shown that some physical properties strongly depend on the intramolecular distribution of the monomeric units. In order to elucidate the relationships between monomer distribution and properties, a copolymer model was prepared by ring‐opening homopolymerization of 3‐methylcyclooctene and successive hydrogenation of the double bonds. Its structure
magnified image
may be considered as that of a copolymer in which one propylene and three ethylene units regularly alternate. Some physical, in particular thermodynamic properties of the model compound were investigated and compared with those of a random copolymer of the same overall composition.
Hydrodynamic properties and unperturbed dimensions of poly‐4‐chlorophenylmethacrylate in various solvents
Authors: Tricot M. , Desreux V.
Published: April 2003

Eight fractions of poly‐4‐chlorophenylmethacrylate prepared by radical polymerization have been studied by viscosity in various solvents, by sedimentation, osmotic pressure and light‐scattering in benzene.

The average unperturbed dimension was obtained in different ways with a good agreement, although the molecular weight range is large. The results as compared with those given for other polymethacrylic esters of the same type show that the effect of a para‐substitution in the phenyl group has little effect on the flexibility of the chain.
Studies in addition polymerization in mixed solvent system part V. Chain transfer of short chain aliphatic alcohols in the polymerization of methyl methacrylate and styrene
Authors: Bhattacharyya Bhupati Ranjan , Nandi Uma Shankar
Published: April 2003

Studies on Polymerization in the presence of alcohols has been carried out using mixed solvent system. It is observed that chain transferring capacity of the aliphatic alcohols do increase with the size of the alkyl group, the order being methyl alcohol < ethyl alcohol < n‐propyl alcohol < iso‐propyl alcohol. The results indicate that α‐hydrogen abstraction from the substrate is effective. The chain transfer constants obtained from the conventional plot of 1/P̄ against S/M is in fair agreement with the values computed from the estimation of hydroxyl end group in the polymer by dye‐partition technique. The increasing transfer constant values in the alochol series with increase in the number of carbon atoms is explained on the basis of probability of available hydrogen atom in the alkyl group. It is also observed that the chain transfer values are affected due to precipitation of polymer. Thermodynamic parameters have been computed from the chain transfer values of alcohols at different temperatures.
Carbon‐13 nuclear magnetic resonance spectroscopy of polypropylene
Authors: Inoue Yoshio , Nishioka Atsuo , Chûjô Riichirô
Published: April 2003

The proton decoupled natural abundance 13C (designated as 13C‐{1H}) high resolution nuclear magnetic resonance spectra were measured for polypropylene at 25.1 MHz. The samples used were 4 polymers of different tacticity. The spectra of methylene carbon split corresponding to diad and partially tetrad placements. The spectra of methyl carbon of stereoblock type polymer clearly split corresponding to pentad placements. These splittings were tentatively assigned. The relation between the relative intensities of pentad placements, namely,

was not satisfied. As the causes of this inequality, several possibilities were pointed out.

The triad microtacticity of highly isotactic polymers determined from 13C‐{1H} spectra were compared with the results of n‐heptane extraction and good correspondence within experimental error were obtained. The discrimination of configurational sequences of polypropylene by 13C‐{1H} spectra at 25.1 MHz is equal or superior to that possible in 1H spectra at 220 MHz. However, the two peaks assigned to methine carbon showed abnormal intensities.
Reaction products of diphenyl sulfide with formaldehyde. Formaldehyde resins. 98
Authors: Kunieda Norio , Suzuki Akira , Kinoshita Masayoshi , Imoto Minoru
Published: April 2003

The acid‐catalyzed condensation of formaldehyde and diphenyl sulfide was carried out in benzene in the presence of p‐toluene sulfonic acid. From the products, four poly(methylene diphenyl sulfides) of the following structures were isolated.
magnified image
Synthesis and thermal characterization of cross‐linked Ti, Zr and Hf polyesters from poly(acrylic acid)
Authors: Carraher Charles E. , Piersma John D.
Published: April 2003

The synthesis of cross‐linked polyesters from the condensation of poly(acrylic acid) with Group IV B dicyclopentadiene dichlorides via the interfacial and solution techniques is described. The polyesters are believed to contain the following repeating units:
magnified image
Thermal properties of the polyesters were studied by Differential Scanning Calorimetry and Thermal Gravimetric Analysis.
Evaluation of the hydrocarbon condensation polymerisation reaction by means of model compounds. I. The reaction with n‐alkyl‐bromides
Authors: Davis A. , Richards D. H. , Scilly N. F.
Published: April 2003

The title polymerisation involves the reaction in tetrahydrofuran of α‐methylstyrene (M) with lithium in the presence of an alkyl dihalide (RX2) to form copolymers. This paper describes a method of studying the effect of changing the experimental parameters on the structure of these copolymers by replacing the dihalide with the corresponding monohalide (HRX). The study is confined to n‐alkyl bromides and the relative amounts of the molecules HR–RH and HRMnRH (where n = 1, 2, and 3) have been determined by g.l.c. By this means it is shown that the reaction is diffusion controlled and the rate proportional to lithium surface area. At 1 : 1 monomer : monohalide stoichiometry (equivalent to 2 : 1 monomer : dihalide in the polymer system) the product is ∼ 90% HRM2RH indicating that the copolymer under these conditions is highly regular with the repeat unit [M–M–R] predominating. The system is extremely sensitive to the reactant ratio and small deviations from stoichiometry result in significant reductions in dimer yield.
Evaluation of the hydrocarbon condensation polymerisation reaction by means of model compounds. II. The reaction of with n‐alkyl chlorides and iodides, and sec‐ and tert‐alkyl bromides
Authors: Davis A. , Richards D. H. , Scilly N. F.
Published: April 2003

The title polymerisation involves the reaction in tetrahydrofuran of α‐methylstyrene (M) with lithium in the presence of an alkyl dihalide (RX2) to form copolymers. Replacement of the dihalide by the analogous monohalide RX gives small molecules, the relative amounts of which furnish information on the polymerisation process and the resulting structures of the copolymers. This paper describes the use of n‐alkyl iodides and chlorides, and sec‐ and tert‐bromides in this regard.

n‐Alkyl iodides were found to behave in a similar manner to n‐alkyl bromides (Part I) with high yields of the dimer HRM2RH being obtained at 1 : 1 M stoichiometry. On the other hand, n‐alkyl chlorides gave a variety of additional products under these conditions and a structural analysis of these materials showed that they resulted from reactions involving n‐alkyl lithium which was formed by the chloride reacting directly with the lithium. This difference in behaviour is explained in terms of the high strength of the carbon‐chlorine bond and implies that copolymers prepared with dichlorides are less regular than those obtained with dibromides.

sec‐ and tert‐bromides also gave a variety of products at equimolar stoichiometry and this was shown to be due to the β‐hydrogen elimination reaction becoming significant. Elimination was most prominent with the tert‐bromides, accounting for about 60% of der termination reaction of the dimer.
Polymerization of methyl methacrylate in the presence of ferric nitrate
Authors: Narita Hiroshi , Sakamoto Yoshiaki , Machida Seishi
Published: April 2003

The polymerization of methyl methacrylate in the presence of ferric nitrate was studied. In spite of the conventional concept that the ferric salt is an inhibitor, the rate of polymerization was found to increase with increasing concentration of ferric nitrate in the range below 1.0·10−3 mole·1−1, and is represented by

An interaction between methyl methacrylate and ferric salt was detected by means of visible and infrared absorption spectra. As the effect of ferric salt shows up in the CO band rather than CC band, the ferric salt is considered to coordinate to the oxygen of the carbonyl group of methyl methacrylate to form a complex. The polymerization reaction proceeds via a radical mechanism, and probably is initiated by the decomposition of the complex. On the copolymerization of methyl methacrylate with styrene and methacrylamide, no effect of ferric salt is observed with respect to the compositions of the resulting copolymers. It is considered that the ferric salt initiates the polymerization only within a range of its lower concentrations. At higher concentrations, the ferric salt terminates the polymerization.
The development of a cryoscopic apparatus
Authors: Stepto R. F. T. , Waywell D. R.
Published: April 2003

The development and use of a cryoscopic apparatus are described. Temperatures are simply measured by means of a thermistor and WHEATSTONE bridge. However, the thermal conditions within the cryoscopic cell during freezing were closely controlled with the result that a quick and accurate method for determining a series of freezing points without supercooling was made possible. The apparatus and method have been tested using solutes of molecular weights up to 2000.
Radical terpolymerization of vinyl sulfide, vinyl ether, and maleic anhydride. Evaluation of the reactivities of vinyl sulfide and vinyl ether alternative copolymerization. IV
Authors: Inoue Hiroshi , Otsu Takayuki
Published: April 2003

The terpolymerizations of maleic anhydride (MAn), vinyl sulfide (VS) and vinyl ether (VE) initiated by α.α′‐azobisisobutyronitrile were investigated in order to evaluate the reactivities of VS and VE toward poly(MAn) radical. Since both VS and VE undergo alternative copolymerization with MAn, these terpolymerizations were approximately treated on the basis of the free propagation and complex propagation mechanisms. From the treatment of the free propagation mechanism in which only three free monomers can participate, the reactivity of the free VS toward attack of the poly(MAn) radical was found to be 4.24 to 6.63 times higher than that of free VE, and the difference in activation energy was 1.5 kcal/mole. The higher reactivity of VS than VE might be explained by the 3 d orbital resonance between the propagating radical and the adjacent sulfur atom in VS. According to the complex propagation mechanism in which only two complexed monomers can participate, the reactivity ratios of the MAn/VS and MAn/VE complex monomers were also determined. It was found that the former complex was more reactive than the latter complex toward the poly(MAn) radical.
Fließverhalten und molekulare struktur von polymeren und ihren lösungen eine systematik quantitativer beziehungen
Authors: Hoffmann M.
Published: April 2003

Viskositäten bei kleinen und hohen Schubspannungen, kritische Schubspannungen der Strukturviskosität, Gummimoduli verhakter Polymerer, Konzentrationen beginnender Verhakung und Grenzviskositätszahlen hängen von Strukturparametern in quantitativer (Molekulargewicht, Uneinheitlichkeit, Konzentration, chemische Natur bzw. Kettendicke) oder in bisher erst qualitativ erkannter Weise (verschiedene Verzweigung, chemische Uneinheitlichkeit, Sequenzstruktur, Phasentrennung und Kristallisation) ab.

Mehrere neue Gesetze werden mitgeteilt. Alle Beziehungen sind stärker untereinander verknüpft als bisher angenommen wurde und liefern einige phänomenologisch vergeblich gesuchte Gesetze für das Verhalten von Mischungen und Lösungen.
Synthese, thermostabilität und elektrische eigenschaften von tiefgefärbten polymeren mit anellierten phthalocyaninartigen systemen
Authors: Wöhrle Dieter , Kossmehl Gerhard , Manecke Georg
Published: April 2003

2.5‐Diamino‐3.4‐dicyanthiophen wurde mit Terephthalsäuredichlorid zu einem Polyamid und mit Thiophen‐2.5‐dicarbaldehyd zu einem Polyazomethin umgesetzt. An beide Polymere konnte durch Reaktion mit Phthalodinitril und Kupferacetylacetonat ein phthalocyaninartiges System anelliert werden. Durch diese Anellierung wurde die thermische Stabilität der Polymeren gesteigert. Die elektrische Leitfähigkeit der beschriebenen Polymeren wurde mit einer neuen Meßzelle gemessen, die die Messung in jeder beliebigen Atmosphäre oder im Vakuum bei Drücken bis zu 5000 kp · cm−2 und bei Temperaturen bis zu 150°C gestattet.
Crystal structure of oligourethane. III. Crystal structure of acetoxy(pentamethyleneurethane) dimer
Authors: Tagawa Hiroyuki , Wada Eiichi , Sakurai Tosio
Published: April 2003

The crystal structure of acetoxy(pentamethyleneurethane) dimer,

was studied by the X‐ray diffraction method. The crystal is triclinic with

The diffraction patterns clearly show the existence of a subcell which is also triclinic with two (CH2)2 units in the unitcell. The subcell structure was determined by use of special non space group extinctions. The proposed crystal structure is that each of the two molecular chains in the main unit cell is connected side by side with other chains in the neighbouring cells by two hydrogen bonds to form molecular sheets parallel to the bs cs plane.
Condensation polymerization of nucleotide analogues
Authors: Seita Toru , Yamauchi Kiyoshi , Kinoshita Masayoshi , Imoto Minoru
Published: April 2003

3‐(9‐Adenyl)‐, 3‐(3‐adenyl)‐, 3‐(9‐hypoxanthyl)‐ and 3‐(3‐hypoxanthyl)‐2‐hydroxypropyl dihydrogenphosphates were condensed in the presence of a large excess of N.N′‐dicyclohexylcarbodiimide (DCC). The major part of the oligomeric products is soluble in water and has a molecular weight of more than 1000 according to gel‐filtration measurement. The absorption spectra show 3% of hypochromism for mixtures of the oligo‐3‐(9‐adenyl)‐2‐hydroxypropyl phosphate with denaturated yeast RNA or sperm DNA.