bluuebunny/crossref_metadata_2025 huggingface dataset:
Transition conformationnelle de certains polymères vinyliques en solution dans de solvants binaires
Authors: Gargallo Ligia
Published: April 2003

Le comportément viscosimétrique de poly(vinyl‐1 pyrrolidone‐2), de poly(méthacrylate de p‐tert‐butylphényle) et de poly(méthacrylate de p‐tert‐butylcyclohexyle) a été étudié dans des mélanges de dioxanne‐1,4/chloroforme à des differentes compositions.

Dans le cas du poly(méthacrylate de p‐tert‐butylcyclohexyle), on a trouvé l'existence d'un comportement irrégulier qui a été interprété en termes de transitions conformationnelles de la chaîne polymérique due au changement de la composition du mélange binaire. L'interprétation est basée sur une modification produite par le passage d'une conformation ordonnée, stabilisée par le dioxanne‐1,4 dans un milieu de concentration chloroformique faible, vers une conformation moins ordonnée de la chaîne qui serait plus stable et energétiquement favorisée dans un milieu riche en chloroforme.

Une évidence spectroscopique de ces transformations a été aussi détectée. Le déplacement et modification de l'intensité des bandes d'absorptionne pourraient pas être dues à une interaction du type polymére‐solvant ce qui suggére une interaction intramoléculaire des groupements chromophores du polymére qui sérait différente pour chaque conformation.
Synthèse de copolymères séquencés par réaction entre des polymères ω‐et α,ω‐hydroxylés et des polymères ω‐et α,ω‐oxychloroformylés
Authors: Pinazzi Christian , Esnault Jacques , Pleurdeau Alain
Published: April 2003

La présente étude a pour but la réalisation de copolymères séquencés. Ces derniers sont synthétisés par réaction de condensation entre des homopolymères α‐ ou α,ω‐hydroxylés de motif monomère A et des homopolymères α‐ ou α,ω‐oxychloroformylés de motif monomère B. Les polymères utilisés dans cette étude sont des polyisoprènes, polybutadiènes α‐ ou α,ω‐hydroxylés et des polystyrènes α‐ ou α,ω‐oxychloroformylés. Les séquences des copolymères sont liées entre elles par des liaisons du type carbonate résultant de la réaction des fonctions terminales hydroxyle et oxychloroformyle. La structure de ces copolymères est confirmée par spectroscopie de NMR et IR et par des measures de masses moléculaires moyenne en nombre.
Teilchenbildung und abbruchsreaktion bei der fällungspolymerisation von styrol in methanol
Authors: Hoffmann Martin
Published: April 2003

Zu Beginn und in Gegenwart von nur wenig gefälltem Polymerem entspricht die Kinetik der Fällungspolymerisation von Styrol derjenigen von Lösungspolymerisationen, wobei jedoch das Verhältnis von Abbruchs‐ und Wachstumskonstante bei Molekulargewichten oberhalb 5000 erheblich größer als bei Lösungspolymerisationen ist.

Bei Umsätzen unterhald 0,05% stellt sich eine während der weiteren Polymerisation konstante Teilchenzahl N ein. Bei konstanter Monomerkonzentration steigt N mit dem Quadrat des Molekulargewichtes, sinkt also mit wachsender Initiatorkonzentration ab. Die Theorie der Teilchenbildung muß deshalb neu überdacht werden.

Gefälltes Polymeres vergrößert die Polymerisationsgeschwindigkeit proportional zu seiner Oberfläche, ohne die Polymerisation in der Lösung zu verändern. Nur ein kleiner Teil der entstehenden Polymerradikale lagert sich vor dem Abbruch des Wachstums an Teilchen an und polymerisiert auf deren Oberfläche weiter. Der Abbruch eines adsorbierten Radikals erfolgt um so seltener, je größer die Oberfläche aller Teilchen ist. Deshalb steigt seine kinetische Kettenlänge und damit die Uneinheitlichkeit des gesamten Polymeren mit dem Umsatz. Der Flächenbedarf eines Radikals hat die erwartete Größenordnung.
Bestimmung der langkettenverzweigung von hochdruckpolyäthylen durch streulicht‐ und viskositätsmessungen
Authors: Casper Rudolf , Biskup Ulrich , Lange Heinz , Pohl Uwe
Published: April 2003

Lineares und verzweigtes Polyäthylen wurden durch Lösungsmittel‐Gradienten‐Chromatographie fraktioniert. Die Fraktionen wurden durch Streulicht‐ und Viskositätsmessungen charakterisiert und die Beziehungen zwischen Molekulargewicht und Viskositätszahl bzw. Trägheitsradius in α‐Chlornaphthalin bei 127°Cermittelt. Der Exponent in der Beziehung

zwischen dem Verhältnis 〈gη〉Θ der Viskositätszahlen von verzweigten und linearen Fraktionen gleichen Molekulargewichts Mw und dem entsprechenden Verhältnis 〈gη〉Θ,w der Trägheitsradien für Θ‐Bedingungen ergab sich zu

Durch diese Gleichung kann die Langkettenverzweigung von Hochdruckpolyäthylen aus dem in thermodynamisch guten Lösungsmitteln bestimmten Viskositätszahlverhältnis 〈gη〉, das mit dem im Θ‐Lösungsmittel bestimmten 〈gη〉Θ im Rahmen der Meßgenauigkeit übereinstimmt, ermittelt werden. Für die untersuchten verzweigten Polyäthylen‐Fraktionen ergaben sich nahezu unabhängig vom Molekulargewicht etwa 1,4 Langkettenverzweigungen pro 1000 C‐Atome.
Copolymerization of polar vinyl monomers with butadiene in the presence of Lewis acids
Authors: Kuran Witold , Pasynkiewicz Stanisław , Nadir Riad , Kowalewska Barbara
Published: April 2003

The copolymerization of acrylonitrile (AN), methacrylonitrile (MAN), methyl acrylate (MA), and methyl methacrylate (MMA) with butadiene (BD) in the presence of ethylaluminium dichloride, zinc chloride, and stannic chloride was investigated. The reactivity of polar monomers in the copolymerization was found to decrease in the following order: AN>MAN>MMA>MA. It was also found that AN and MAN form with BD copolymers of essentially 1:1 composition; MMA, and particularly MA were found, however, to form with BD copolymers of a composition different from 1:1.

In competition with the copolymerization, a Diels‐Alder reaction was shown to occur in the investigated systems. The reactivity of polar monomers in the Diels‐Alder reaction was found to increase in the following order: MAN<AN<MMA<MA. In the presence of aluminium bromide and of antimony chloride these monomers were found to produce with BD the corresponding Diels‐Alder adducts but not the copolymers.

The obtained results are discussed in terms of the electron‐accepting properties of polar vinyl monomers and of the stability of transient charge‐transfer complexes between the monomers involved in the copolymerization and the Diels‐Alder reaction.
Linear oligopeptides, 29. Infrared conformational analysis of homo‐oligopeptides in the solid state and in solution
Authors: Palumbo Manlio , da Rin Silvio , Bonora Gian Maria , Toniolo Claudio
Published: April 2003

The IR spectra of eight series of monodisperse, chemically and optically pure, protected linear homo‐oligopeptides having the general formula Boc(LX)nOMe, where X = Ala, Nva, Val, Leu, Ile, Phe, Met, Cys(Me), and n = 2–7, were investigated by IR absorption spectroscopy in the solid state and in solution. The measurement in the solid state indicate that all pentamers and higher oligomers assume essentially a β‐form; trimers and tetramers present evidence of mixtures of β‐ and unordered structures, while in dimers the unordered structure is largely predominant. The occurrence of the unusual intermolecular β‐parallel conformation was suggested for HCl·H(LX)7OMe, where X = Val, Ile, and Phe. Further, the absorbance in the NH stretching region was determined as a function of concentration in deuterochloroform. This conformational analysis in solution showed that a high content of intramolecularly hydrogen‐bonded forms exist in all homo‐tetramers with the exception of those derived from the β‐branched amino acid residues, valine and isoleucine. The effect of the presence of a sulfur atom or an aromatic ring in the amino acid side chain (S‐methyl cysteine, methionine, and phenylalanine peptides) on the stability of the folded forms is also discussed.
Ein Beitrag zur Teilchenbildung bei der Emulsionspolymerisation von Acrylsäure‐ und Methacrylsäureestern
Authors: Sütterlin Norbert , Kurth Hans‐Joachim , Markert Gerhard
Published: April 2003

Zur Beschreibung der Teilchenbildung bei der Emulsionspolymerisation werden im allgemeinen zwei Denkansätze herangezogen. Gemäß Harkins, Smith und Ewart spielt die mit Monomeren angequollene Emulgatormicelle hierbei die maßgebende Rolle. Nach Fitch und Roe hingegen erfolgt die Teilchenbildung, indem in der Wasserphase gebildete Oligomerenradikale ihr Löslichkeitsgleichgewicht überschreiten.

Die Praxis bei der Emulsionspolymerisation von Acrylsäure‐ und Methacrylsäureestern hat gezeigt, daß die Vorstellungen von Fitch‐Roe den wahrscheinlicheren Fall darstellen. Bei einer Betrachtungsweise über ein Lösungs‐Fällungsgleichgewicht ist es naheliegend, der Monomerengleichgewichtskonzentration in der Wasserphase und damit gleichlaufend der Hydrophilie des Polymeren größere Aufmerksamkeit zu widmen.

Trägt man die mittlere Teilchenzahl ND pro Einheitsvolumen als Funktion der zu Beginn der Polymerisation vorliegenden Emulgatorkonzentration [E] auf, erhält man in doppeltlogarithmischem Maßstab die bekannten S‐fömigen Abhängigkeiten, in denen die kritische Micellkonzentration des verwendeten Emulgators keinen exponierten Kurvenpunkt darstellt. Die Teilchenzahl für eine bestimmte Emulgatorkonzentration ist dabei von der Sättigungskonzentration [M] der Monomeren in der Wasserphase abhängig.

Bei den im allgemeinen viel zu wenig beachteten Agglomerationsvorgängen hat man zwischen einer Primäragglomeration und einer Sekundäragglomeration zu unterscheiden. Besonders bei den hydrophilsten Vertretern der Acrylat‐ bzw. Methacrylatreihe wirken sich diese Agglomerationserscheinungen auf die mittlere Teilchenzahl aus. Eine Ursache dafür dürfte die Emulgatorgleichgewichtskonzentration in der Teilchengrenzenfläche sein, die mit steigender Hydrophilie des Polymerisats abnimmt.
Reaktive mikrogele, 4. Über besonderheiten bei der emulsionspolymerisation von 1,4‐divinylbenzol
Authors: Obrecht Werner , Seitz Ulrich , Funke Werner
Published: April 2003

Es wurde die Emulsionspolymerisation von 1,4‐Divinylbenzol mit Natrium‐dodecylsulfat als Emulgator und Kalium‐peroxodisulfat als Initiator untersucht mit dem Ziel, reaktive Mikrogele mit verschiedenen Teilchen‐Durchmessern zu synthetisieren. Gegenüber der Emulsionspolymerisation von Styrol wurden bei 1,4‐Divinylbenzol die Ausbildung von Koagulat, verschiedene Agglomerationsstufen und schließlich eine wesentlich höhere Partikelzahl gefunden. Die möglichen Ursachen der genannten Besonderheiten werden diskutiert.
Tetraaza[14]annulen‐Derivate und ihre Vorstufen, 2. Bicyclische Verbindungen und polymere Substanzen
Authors: Müller Reinhardt , Wöhrle Dieter
Published: April 2003

3,3′‐Diaminobenzidin (1) und 1,2,4,5‐Tetraaminobenzol (7) reagieren mit 3,3′‐(1,2‐Phenylen‐1,2‐diimino)dipropenal (2) im Molverhältnis 1:2 zu bicyclischen Tetraaza[14]annulenen 3 bzw. 8 und mit Propinal (4) oder Acetylaceton im Molverhältnis 1:2 zu polymeren Tetraaza[14]annulenen 9 bzw. 10. Durch Komplexierung mit Salzen der zweiwertigen Übergangsmetalle Kupfer, Nickel, Kobalt und Eisen wurden die entsprechenden bicyclischen und polymeren Metallchelate 11a—d, 12a—d und 13a—d, 14a—d dargestellt. Alle Verbindungen wurden durch IR‐, Elektronen‐ und Massenspektren sowie durch Elementaranalysen charakterisiert.
Asymmetric synthesis catalyzed by poly‐L‐alanine
Authors: Ueyanagi Kaoru , Inoue Shohei
Published: April 2003

Asymmetric addition of dodecanethiol to isopropenyl methyl ketone catalyzed by the terminal amino group of poly‐L‐alanine (PLA) and its terminal models was studied. When PLA was used as catalyst, the [α]D value of the product, 1‐(dodecylthiomethyl)ethyl methyl ketone, was larger than in the case of catalysis by the terminal models of PLA, indicating the importance of conformation of the polymer catalyst in asymmetric reaction. On the other hand, on addition of ethanol to the reaction system, the [α]D of the product was increased in each case.
Cathodic polymerization of maleic anhydride with N‐methylpyridinium iodide
Authors: Bhadani Suraj N. , Prasad Jagdeo
Published: April 2003

The electrochemical homopolymerization of maleic anhydride was investigated at constant electric current in a divided cell. The polymer yield depended markedly on the quantity of current passed through the solution, polymerization time, and on the nature of supporting electrolytes and solvents. The visible spectra of electrolysed solutions and the IR spectra of poly(maleic anhydride) were measured. The polarographic measurements revealed that N‐methylpyridinium iodide, employed as supporting electrolyte for the polymerization of maleic anhydride, was reduced at a smaller cathodic voltage than maleic anhydride. Under the given reaction conditions the electrolytic reduction products of the salt might have initiated the polymerization. An anionic polymerization mechanism is assumed.
Untersuchungen über poly(arylenvinylen)e, 13. Phenylsubstituierte poly‐p‐xylylidene. Durch UV‐licht induzierte photoleitfähigkeit im NIR
Authors: Hörhold Hans‐Heinrich , Opfermann Johannes
Published: April 2003

UV‐Irradiation of phenyl‐substituted poly‐p‐xylylidenes induces photoconductivity in the range of 7000–17000 cm−1. The spectral distribution is identical with that of photoconductivity found in macromolecular radical cations produced chemically by oxidation with antimony pentachloride. This supports the assumption that the induced photoconductivity can be attributed to the photochemical generation (UV) and the optical excitation (VIS/NIR) of macromolecular radical ions.
Vinyl polymerization by metal complexes, 30. On the initiation mechanism of vinyl polymerization by the system copper(II) chelate of poly(vinyl alcohol)/carbon tetrachloride: Spin trapping and gelation studies
Authors: Kimura Keiichi , Inaki Yoshiaki , Takemoto Kiichi
Published: April 2003

The initiation mechanism of vinyl polymerization by a copper(II) chelate of poly(vinyl alcohol) was studied in aqueous solution in the presence of carbon tetrachloride, in order to determine the free radical species formed during the initiation step. Trichloromethyl radicals were ascertained to be the main initiation species, by spin trapping and gelation experiments. Differences in polymerization activity between methyl methacrylate and acrylonitrile are discussed.
Unidirectional compression measurements on swollen polystyrene model‐networks
Authors: Belkebir‐Mrani Ahmed , Herz Jean Edouard , Rempp Paul
Published: April 2003

The elastic behavior of swollen polystyrene model‐networks, prepared by anionic block‐copolymerization of styrene with small amounts of divinylbenzene, has been studied by unidirectional compression measurements.

The compression modulus G* as defined in the present paper, was related to the structural characteristics of the networks and to the interaction parameters of the systems. The influence of these various parameters on the gel behavior has been discussed.

From comparison between uniaxial compression measurements and X‐ray diffraction data on the same gels, it was shown at least qualitatively, that the elastic chain‐interpenetration depends upon the functionality of the crosslinkages.
Partially aromatic polyamides: A calorimetric and dynamic‐mechanical investigation
Authors: Manescalchi Francesco , Pizzoli Maria , Drusiani Annamaria , Zanetti Franca
Published: April 2003

Some partially aromatic polyamides were prepared from hexamethylenediamine and the following dicarboxylic acids: 4,4′‐dimethyl‐4,4′‐p‐phenylenedipentanoic acid, 3,3′‐dimethyl‐3,3′‐p‐phenylenedibutanoic acid, 3,3′‐p‐phenylenedibutanoic acid, and 3‐methyl‐3,3′‐p‐phenylenedipropanoic acid. From the dynamic‐mechanical and thermal investigations it appears that the substitution of H‐atoms with methyl groups adjacent to the phenylene ring very little affects the glass transition temperature of the polyamides, but seems to impede chain packing and thus lowering both melting points and crystallinity. The annealing below the glass transition temperature Tg was also explored. The development of endothermic peaks in the glass transition region is interpreted in terms of localized order.
Study of the mechanism of propagation and transfer reactions in the polymerization of olefins by Ziegler‐Natta catalysts, 4. The kinetic scheme for propagation and chain transfer reactions
Authors: Zakharov Vladimir A. , Bukatov Gennadii D. , Chumaevskii Nikolay B. , Yermakov Yurii I.
Published: April 2003

On the basis of the experimental data on the number of propagation centers, activation energy, and rate constants of propagation and transfer reactions, a kinetic scheme for propagation and chain transfer reactions in the polymerization of olefins in the presence of Ziegler‐Natta catalysts is considered. The main features of this scheme are: (a) monometallic composition of propagation centers; (b) two‐stage mechanism of the propagation reaction: (c) the reversible adsorption of an organoaluminium cocatalyst on the titanium of the propagation center resulting in its temporary deactivation and chain transfer with an organoaluminium compound.
Metalloporphyrins in polymeric matrices and in micelles, 2. Iron porphyrins and cobalt porphyrins in copolymers of styrene and 1‐vinylimidazoles
Authors: Fuhrhop Jürgen‐Hinrich , Besecke Siegmund , Vogt Walter , Ernst Josef , Subramanian Japyesan
Published: April 2003

Copolymers from styrene and 1‐vinylimidazoles (4a–f), form low spin adducts with iron(II) porphyrins and iron(III) porphyrins, when the content of imidazolyl groups in the polymer is ten mole percent or more. With polymers having a content of imidazolyl groups of less then one mole percent, only high spin adducts are observed. With terpolymers, in which the porphyrin is covalently bound to the copolymer the same phenomenon is observed. Only the high spin Fe(II) porphyrin adducts in the solid state adsorb molecular oxygen like cobalt(II) porphyrins under the same conditions. Adsorptions and desorptions of oxygen are much slower in the cases of iron(II) porphyrins than with the cobalt(II) porphyrins. Electronic and ESR spectra as well as susceptibility measurements were used to characterize the reported spin states.
Pfropfung und vernetzung mittels azogruppen enthaltender copolymerer, 6
Authors: Kerber Robert , Nuyken Oskar , Steinhausen Rainer
Published: April 2003

Copolymers containing styrene and 2‐(4‐vinylphenylazo)‐2‐methylmalononitrile units were grafted with acrylonitrile. It was found that kinetically this reaction behaves similar to the acrylonitrile polymerisation initiated by low‐molecular azocompounds. The reaction products were fractionated into graft‐copolymer, ungrafted backbone‐polymer and polyacrylonitrile. The characteristic values for the grafting reaction (ε, UG, π) were determined.
Synthesis of poly(3‐vinyl‐1,4‐butyrolactone‐co‐acrylonitrile)
Authors: Shimidzu Takeo , Yoshikawa Masakazu , Chiba Hisashi , Murakami Akira
Published: April 2003

Copolymerizations of 3‐vinyl‐1,4‐butyrolactone (1) and acrylonitrile (2) initiated by dibenzoyl peroxide or 2,2′‐azoisobutyronitrile were carried out. The following reactivity ratios were found for the bulk copolymerization at 70°C for 1: r1 = 0,078±0,037 and for 2: r2 = 4,7±0,3. In addition the values Q1 = 0,033 and e1 = 0,053 were obtained. The ring opening and the ring closing of the lactone moiety in the polymer with an alkaline and an acid were found to be reversible.
Interaction between dyes and polyelectrolytes, 7. Metachromatic behavior of methylene blue induced by poly(sodium acrylate) and its homologues
Authors: Shirai Masamitsu , Murakami Yoshihiro , Tanaka Makoto
Published: April 2003

The structural effect of polyanions on the metachromatic behavior of methylene blue (1) was investigated spectrophotometrically. The following polyanions were used: poly(sodium acrylate) (PAA), conventional poly(sodium methacrylate) (a‐PMA), isotactic poly(sodium methacrylate) (i‐PMA), syndiotactic poly(sodium methacrylate) (s‐PMA), and the copolymer poly(sodium maleate‐covinyl alcohol) (1:1) (PMVA). The metachromatic behavior was followed by the changes in the molar absorption coefficient (ε) at 664 nm of methylene blue (1) and in the wave length (λm) of the metachromatic band. Important factors for metachromasy were found to be the flexibility and charge density of the polymer. Differences between OSO and COO⊖ as binding sites are discussed.
Study of the isothermal bulk polymerization of diallyl fumarate and related compounds by differential scanning calorimetry
Authors: Černec Franc , Osredkar Uči , Može Adolf , Vizovišek Ivan , Lapanje Savo
Published: April 2003

Course and kinetics of the isothermal bulk polymerization of diallyl fumarate and the course of the polymerization of diallyl fumarate, diallyl maleate, and diallyl succinate by programmed heating were studied. 2,2′‐Azoisobutyronitrile was used as initiator. The isothermal bulk polymerization was investigated at temperatures between 75 and 96°C and initiator concentrations ranging from 22,5 to 62,5 mmol/dm3 were applied. The bulk polymerization by programmed heating was investigated at temperatures between 40 and 190°C and at constant initiator concentration of 62,5 mmol/dm3. The negative value of the heat of isothermal bulk polymerization of diallyl fumarate at 75°C at the initiator concentration of 22,5 mmol/dm3 was found to be −63,6 kJ/mol and to increase with increasing temperature to −87,9 kJ/mol at 96°C. Also an increase was observed at higher initiator concentrations in the same temperature range. The initial rate constants for the isothermal bulk polymerization of diallyl fumarate were determined and from them the overall activation energy (100,4 kJ mol). It was found that the overall rate of polymerization at low degrees of conversion depends on the square root of the initiator concentration. The heats of the polymerization by programmed heating at constant initiator concentrations for diallyl fumarate, diallyl maleate, and diallyl succinate were found to be −126,4, −82,9, and −90,8 kJ/mol, respectively. In all cases the DSC‐curves display two peaks. On the basis of the results obtained, it was possible to interpret the differences in reactivity of individual functional groups in these compounds observed in programmed heating.
Étude par 13C NMR et 1H NMR du dextrane et de ses dérivés acétylés et benzylés
Authors: Gagnaire Didier , Vignon Michel
Published: April 2003

A 13C NMR and 1H NMR study has been performed on a bacterial dextrane, its triacetylated derivative and a synthetic tri‐O‐benzyldextrane obtained by polycondensation. The main feature of these three products is their regular linearity of glucose residues linked α‐D‐(1→6). In each of them, the proton signals were assigned by homonuclear double irradiation and the 13C signals by selective proton irradiation.

The 13C chemical shifts of isomaltose and gentiobiose are compared with the shifts of the corresponding homopolymers dextrane and pustulane.
Zur fraktionierung von polymeren durch direktextraktion
Authors: Holtrup Wolfgang
Published: April 2003

A method of solution fractionation by direct extraction is described for the purposes of determining molecular weight distributions and preparing almost monodisperse fractions. Unexpectedly, rapid phase equilibration is obtained by vigorous vibrational agitation of powdered polymers in corresponding solvent systems. In the case of high density polyethylene, phase equilibration proceeds within 5 min and is independent of particle size up to a diameter of 1 mm. Molecular weight distributions determined by the direct extraction technique deviate only slightly from those obtained by conventional gel permeation chromatography. Besides polyethylene also other well‐known polymers were fractionated by this method. It is especially well applicable to partially crystalline polymers, but less applicable to amorphous polymers.
Carbon‐13 NMR spectra and reactivities of vinyl compounds in ionic and radical polymerizations
Authors: Hatada Koichi , Nagata Kazuhiko , Hasegawa Toshihiko , Yuki Heimei
Published: April 2003

The 13C‐chemical shift of β‐carbon in the vinyl group of monomers was correlated with the relative reactivity of the monomer in the cationic copolymerizations of substituted styrenes, benzyl vinyl ethers, and phenyl vinyl ethers and also in the copolymerization of substituted styrenes by Ziegler catalysts. It was found that the β‐carbon resonates at the higher field, the higher the reactivity of the monomer is. The reverse was the case in the anionic addition reaction of substituted styrene to living polystyrene. The relations were also studied between the 13C‐chemical shift and the e‐value of the monomer and some direct evidence was obtained for the validity of the Q–e scheme. From these results it was revealed that the 13C‐chemical shift of vinyl compounds is an important tool for the examination of the mechanism of polymerization reaction.
Vernetzte polymere mit spaltbaren netzbrücken, 5. Homopolymerisation von 4‐vinylbenzoesäureanhydrid
Authors: Braun Dietrich , Brendlein Wolfgang , Jung Jin Chul
Published: April 2003

The kinetics of the crosslinking homopolymerization of symmetrical diolefines with independent double bonds is described. Experiments are carried out with 4‐vinylbenzoic anhydride. The experimental results are compared with the theory and the discrepancy is discussed.
Über den thermischen abbau des poly(ε‐caprolacton)s
Authors: Lüderwald Ingo
Published: April 2003

The thermal and electron impact induced degradation reactions of poly(ε‐caprolactone) {poly[oxy(1‐oxohexamethylene)]} were investigated in a mass spectrometer. It can be shown that the favorated thermal degradation reaction is the cleavage of the ester bond and formation of ω‐hydroxyl and ketene endgroups (Eq. (iii)) and with a lower intensity the cleavage of the OCH2‐bond and formation of carboxyl‐and pentenyl endgroups (Eq. (vii)). After electron impact and fragmentation of the pyrolysis products to carboxonium ions an elimination of caprolactone via a “zip”‐mechanism can be observed (Eq. (v)).
Evaluation of the rate constant for primary radical termination in free radical polymerization
Authors: Mahabadi Hadi K. , O'Driscoll Kenneth F.
Published: April 2003

Styrene and methyl methacrylate were polymerized with azodiisobutyronitrile (AIBN) at 50, 60, and 70°C. The average degree of polymerization was kept constant while changing the initiator concentration, by using 1‐butanethiol as a chain transfer agent. In these polymerizations, a deviation from the simple kinetic rate law was noticed. This deviation was explained in terms of primary radical termination considering the effect of size dependence of the termination rate constant on the kinetics of free radical polymerization and taking into account the fraction of thermal polymerization. The temperature dependence of the characteristic constant, Ktpr/KpKi, was estimated to be 5,408 · 10−5 exp (12915 cal mol−1/RT) and 7,52 · 10−3 exp (7791 cal mol−1/RT) for styrene/AIBN and methyl methacrylate/AIBN, respectively.
Thermal decomposition of γ‐ray irradiated poly(vinyl fluoride)
Authors: Hagiwara Miyuki , Ellinghorst Guido , Hummel Dieter O.
Published: April 2003

The thermal decomposition of γ‐irradiated poly(vinyl fluoride) has been investigated by means of thermogravimetry (TG), differential thermal analysis (DTA) and mass spectral analysis of the evolved gas. The polymer was found to lose its weight in two main steps. The first step was the elimination of hydrogen fluoride; during the second step various unsaturated hydrocarbons were evolved as a consequence of main chain scission. The kinetical analysis of TG for dehydrofluorination under N2 showed that the apparent overall activation energy decreases with increasing irradiation dose. Considerable heat release during the decomposition was observed when DTA was performed in the presence of air. This behaviour was attributed to a crosslinking reaction catalyzed by O2. The addition of potassium salts or CsCl markedly diminished dehydrofluorination. On the other hand, dehydrofluorination was accelerated by CuF2.
Aqueous polymerisation of acrylonitrile initiated by the V(V)‐ethylene glycol redox system
Authors: Nayak Padma L. , Mohanty Trijama R. , Samal Rajani K.
Published: April 2003

The kinetics of acrylonitrile polymerisation initiated by the redox system V(V)‐ethylene glycol were investigated in aqueous sulfuric acid in the temperature range 40–50°C. The rate of polymerisation, of V(V) disappearance, and the chain lengths of polyacrylonitrile were measured. The effect of certain water miscible organic solvents and certain neutral salts on the rate of polymerisation was investigated. The kinetics are consistent with the formation of an intermediate complex between the diol and the oxidant whose decomposition leads to the initiating radical. A suitable kinetic scheme is proposed and the various rate and energy parameters are computed.
Baker‐Williams fractionation of high molecular weight polyisobutylene and its evaluation by gel permeation chromatography
Authors: Mokhtari‐Nejad Esfandiar , Berger Knud C. , Hammel Reinhart , Lederer Klaus
Published: April 2003

A sample from commercially available polyisobutylene with a viscosity average molecular weight of M̄v = 320 000 is fractioned according to Baker‐Williams. 9 Fractions are recovered and are characterized by viscometry and gel permeation chromatography (GPC). Molecularly very homogeneous fractions with an inhomogeneity U = (M̄w/M̄n)−1 ≈ 0,05 can be obtained in the range of molecular weights up to M̄v = 600 000. Inversion of molecular weight occurs in the last three fractions. A 3 wt.‐% portion with M̄v>106 is lost during the fractionation.
Chemische synthese verzweigter polysaccharide, 5. Kopplung von oligosacchariden und amylose an verschiedene träger durch hydrazonbindung
Authors: Andresz Holger , Richter Gabriele C. , Pfannemüller Beate
Published: April 2003

The coupling of glucose and maltooligomers by hydrazone linkage to carriers by means of acid hydrazide groups was investigated. The following carriers were used: (1) linear polymers such as (a) poly(ethylene glycol) with carboxymethyl (CM) end groups, (b) CM‐amylose and CM‐cellulose, 6‐COOH amylose and 6‐COOH cellulose, pectic acid, alginic acid, poly(acrylic acid); (2) multifunctional centers such as (c) CM‐cyclodextrin, 1,3,5‐benzenetricarboxylic acid, 1,3,4,5‐benzenetetracarboxylic acid, crosslinked poly(acrylamide) (BIO‐GEL). The hydrazone linkage which is formed preferably in borate buffer at pH 8,5 was stable above pH 6 and could be split by mild acid treatment at pH 4. Maltooligomeric grafts of degree of polymerization DP ≧ 4 may be extended enzymatically by phosphorolytic synthesis to amylose chains of variable length. Primer activity of the bound maltooligomers for phosphorylase was obviously not hindered by the hydrazone linkage, by free hydrazide groups, or by synthetic polymers as carriers. ABA‐Block copolymers may be derived from(a), comb‐like molecules from (b), and different kinds of star‐like molecules from (c).
Elektrokinetische untersuchungen an Fasern, 4. Über ein Adsorptionsmodell von ionen an ionenaustauschenden Polymeren
Authors: Aichele Wilfried , Schollmeyer Eckhard , Herlinger Heinz
Published: April 2003

In this part of our series, a thermodynamic description of the zeta‐potential is proposed, which leads under special conditions to the application of Nernst's equation on the Gouy‐Chapman‐layer. Thus the behaviour of the streaming current can be explained by adsorption of different electrolytes at solids. Finally, a relation of electrokinetic effects with redox electrodes is proposed, which might be able to result in the determination of absolute thermodynamic normal potentials.
Synthesis of block copolymers containing polybutyramide blocks
Authors: Nitadori Yoshiaki , Franta Emile , Rempp Paul
Published: April 2003

Several methods were employed to synthesize block copolymers of a polyamide and polystyrene (or polyisoprene). The polystyrenes (or polydienes) were obtained anionically and were fitted with terminal acyllactam functions. In a second step the acyllactam groups were used as promoters for the polymerization of the corresponding lactam. The best results were obtained when the functionalization was carried out with toluene diisocyanate, followed immediately by protonation by means of the lactam itself. This method yields, the highest degrees of functionalization and low coupling rates; the subsequent polymerization of the lactam in the bulk leads to block copolymers which were characterized as such; they were found to contain only small amounts of homopolystyrene, easy to remove.
Dissociation behaviour of some mixtures of synthetic phenolic oligomers in nonaqueous media
Authors: Chatterjee S. K. , Chatterjee Nandita
Published: April 2003

Some phenolic oligomers of uniform structure, molecular weight, and with additional functional groups have been prepared by stepwise synthesis. These synthetic novolaks when mixed in various molecular proportions resemble p‐cresol formaldehyde condensation polymers. A study has been made on the titration curves of the mixtures of synthetic compounds in nonaqueous media. A large number of breaks have been observed in the titration curves, and they occur in simple multiples of the calculated amount of base required to neutralize each acidic group in the various novolak molecules independently. An attempt has been made to interpret some of these observations in terms of intramolecular hydrogen bonding, ion‐association, and homoconjugation.
Deux phases »amorphes« dans les multifilaments préorientés de polyester. Essai d'interprétation à partir de l'analyse calorimétrique différentielle
Authors: Hagège Raoul , Mamy Catherine , Thiroine Claude
Published: April 2003

The reliability of a base‐line correction method—with the use of a computerized calculation—is considered in the case of Differential Scanning Calorimetry (DSC) of preoriented amorphous polyester yarns (POY); the method allows to measure the enthalpies of crystallization and fusion of those materials.

An interpretation of the decrease of the enthalpy of crystallization with the increase of the amorphous orientation is then given; according to this interpretation, POY would be of a two‐phase character, with an oriented amorphous and a disoriented amorphous phase; the crystallization of the disoriented amorphous phase, which occurs at higher temperature, would require a part of the thermal energy liberated by the crystallization of the oriented phase, which takes place at lower temperature. Quantitative results are in good agreement with our working hypothesis, but they have to be supplemented by new experiments.
Effect of amine structure on the photopotential induced by dye / polyamine systems
Authors: Kaneko Masao , Sato Shunichi , Yamada Akira
Published: April 2003

It was found that the photoredox system, dye/poly(iminoethylene) (PEI) induces a remarkably higher photopotential than the corresponding dye/monoamine system. The relationship between the photopotential induced by thionine (TH)/PEI and the number of amino or imino groups in the amine molecule is characterized by an alternating pattern. From the dependencies of the photopotential and the ionic species of the amine on pH, it was concluded that the active species of the amine is the half‐protonated one. As a possible mechanism for the high photopotential induced by the polyamine system, an interaction between the dye and the half‐protonated species is proposed, based on the bifunctional behavior of the adjacent protonated and unprotonated imino groups of PEI.
Structure of polyethylene produced at high pressure by simultaneous ionic and radical mechanisms
Authors: Constantin Didier , Hert Marius , Machon Jean‐Pierre
Published: April 2003

Polyethylene samples of intermediate density were prepared by high‐pressure polymerization with some Ziegler catalysts derived from titanium tetrachloride. These polymers were studied by characterization techniques (fractionation, gel permeation chromatography, viscometry, infrared spectroscopy, differential scanning calorimetry) and three types of macromolecules were identified.
On the polymerization of crystalline 1,4‐diethynylnaphthalene, 1 the structure of the photopolymer
Authors: Rohde Ottmar , Wegner Gerhard
Published: April 2003

Upon irradiation with UV light crystalline 1,4‐diethynylnaphthalene (1) readily polymerizes in the solid state. The purple polymer formed has a polyene polymer backbone and a molecular weight of 9000. Only one ethynyl group of the monomer participates in the polymerization process, whereas the second ethynyl group remains unreacted. The structure of the photopolymer was proven by spectroscopic methods, and direct evidence was obtained from resonant Raman spectra by comparing the photopolymer of the title compound to poly(1‐ethynylnaphthalene) prepared by complex catalysis.
Strukturuntersuchung von Polyestern durch direkten Abbau im massenspektrometer, 5. Polyester aus Terephthalsäure und/oder Bernsteinsäure und Hydrochinon
Authors: Aguilera Carlos , Lüderwald Ingo
Published: April 2003

The structure and thermal degradation behaviour of polyesters from terephthalic and/or succinic acid and hydroquinone were investigated by pyrolysis mass spectrometry. Poly(oxysuccinyloxy‐1,4‐phenylene) (2) undergoes cleavage of the ester bond (Eq. (vii)) as a very selective pyrolysis mechanism at 310°C, whereas the thermally more stable poly(oxyterephthaloyloxy‐1,4‐phenylene) (1) starts to degrade above 400°C and yields pyrolysis products with phenyl (Eq. (iv)), p‐hydroxyphenyl (Eq. (iii)), benzoyl (Eq. (iiv)) and carboxylic end groups. A calibration curve of the intensities of monomer specific fragments, obtained from pyrolysis mass spectra of polyesters from terephthalic acid, succinic acid, and hydroquinone provides the exact determination of their compositions.
Darstellung und eigenschaften von chelatharzen mit pyrazol‐3,4‐dicarbonsäure bzw. 1,2,3‐triazol‐4,5‐dicarbonsäure als ankergruppen
Authors: Manecke Georg , Rühl Christian‐Steffen
Published: April 2003

N‐vinylation of pyrazolecarboxylates and 1,2,3‐triazolecarboxylates with vinyl acetate leads to the formation of the N‐vinylpyrazoles and N‐vinyl‐1,2,3‐triazoles. The structures are determined by mass and NMR spectra. The syntheses of crosslinked poly[1‐(3,4‐dicarboxypyrazol‐1‐yl)ethylene] (12) and poly[1‐(4,5‐dicarboxy‐1,2,3‐triazol‐2‐yl)ethylene] (13) are described. The swelling behaviour, the time dependence of the uptake of Cu2+‐ions and the pH‐dependence of the uptake of Cu2+‐, Zn2+‐, and Mg2+‐ions of these resins were investigated.
The role of co‐operativity in determining the binding behaviour of hetero‐charged polyanions with metachromatic dyes
Authors: Cundall Robert B. , Lawton John B. , Murray David , Phillips Glyn O.
Published: April 2003

The binding of acridine orange to carboxyl and sulfate containing polyanions has been investigated by fluorescence spectroscopy. Particular attention has been given to solutions containing both carboxyl and sulfate groups in two different situations, first where both types of site are present attached to the same polymer backbone in a regular repeating structure (heparin), and secondly where individual polymer chains carry exclusively one type of site (hyaluronic acid/K‐carrageenan mixtures). Greatly differing behaviour of the binding profiles as the concentrations of components were reduced have been explained in terms of the strong co‐operativity of the dye‐binding process. The carboxyl and sulfate sites of heparin appear to be equivalent in binding strength, while those of the polycarboxylate polysulfate mixture are no longer equivalent, binding profiles being dominated by the strong binding sulfate group.
Polymerization of 5,6‐anhydro sugar derivatives, 2. Anionic polymerization of 5,6‐anhydro‐1,2‐O‐isopropylidene‐α‐D‐glucofuranose and synthesis of 5,6‐glucan
Authors: Uryu Toshiyuki , Kitano Kissho , Matsuzaki Kei
Published: April 2003

Poly(5,6‐anhydro‐1,2‐O‐isopropylidene‐α‐D‐glucofuranose) (1) the main chain structure of which is poly(oxyethylene) was obtained by anionic ring‐opening polymerization of 5,6‐anhydro‐1,2‐O‐isopropylidene‐α‐D‐glucofuranose (2) which contains a pendent oxirane ring. Polymerization by strong bases such as sodium hydroxide, potassium hydroxide, cesium hydroxide, and potassium tert‐butoxide gave polymers with degrees of polymerization up to sixteen in high yield. The specific rotations of the polymers were almost constant, being mostly in the range from −44° to −40°. The factors affecting this polymerization were examined in order to elucidate the best conditions for polymerization. The polymer was hydrolyzed to 5,6‐glucan (3) with trifluoroacetic acid‐water at room temperature. The structures of the original polymer 1 and the hydrolyzed one were compared with those prepared by cationic ring‐opening polymerization of 2.
Chelation ion‐exchange properties of poly(8‐hydroxyquinolinediylethylene)
Authors: Patel Bhupendra S. , Patel Shanti R.
Published: April 2003

The polymer prepared from 8‐hydroxyquinoline and 1,2‐dichloroethylene by Friedel‐Craft's condensation, showed to be a selective chelating ion‐exchange resin for certain metal ions. A batch equilibration method was employed in the study of the selectivity of metal ion uptake. This method involved the measurement of distribution of a given metal ion between the polymer sample and a solution containing the metal ions. The study was carried out over a wide pH range and in media of various ionic strengths.
Polyoxirannes et polythiirannes comportant un centre chiral dans la chaine latérale, 1. Synthèse et pureté optique de diastéréoisomères des époxy‐1,2 méthyl‐3 pentane et épithio‐1,2 méthyl‐3 pentane
Authors: Goguelin Michel , Sepulchre Maurice
Published: April 2003

In order to study the polymerization of oxiranes and thiiranes containing an asymmetric carbon atom in the side chain a mixture (mole ratio 1:1) of the diastereoisomers 2R,3S and 2S,3S 1,2‐epoxy‐3‐methylpentane (1a et 2a) and 2R,3S and 2S,3S 1,2‐epithio‐3‐methylpentane (1b et 2b) as well as the almost pure diastereoisomers 2R, 3S (1b) and 2S, 3S (2a) were prepared. The diastereoisomeric composition of these compounds was established by 1H NMR spectroscopy, at 250 MHz for the thiiranes and at 90 MHz for the oxiranes (in the presence of a chiral shift reagent). The optical activities of the different pure diastereoisomers were determined, and the chiroptical properties of these new monomers were studied.
Synthesis of polyamide‐sulfonamides by ring‐opening polyaddition of 2,2′‐disubstituted bis(thiazetidinone 1,1‐dioxides) with aliphatic diamines
Authors: Imai Yoshio , Ueda Mitsuru , Okuyama Kazuo
Published: April 2003

New bifunctional, four‐membered heterocyclic monomers, 2,2′‐m‐xylylenebis(4,4‐dimethyl‐1,2‐thiazetidin‐3‐one 1,1‐dioxide) (1a) and 2,2′‐oxydi‐p‐phenylenebis(4,4‐dimethyl‐1,2‐thiazetidin‐3‐one 1,1‐dioxide) (1b), were synthesized from 2‐chlorosulfonyl‐2‐methylpropionyl chloride and the corresponding diamines. The ring‐opening polyaddition of these monomers 1a and 1b with aliphatic diamines in polar aprotic solvents afforded polyamide‐sulfonamides having inherent viscosities of 0,1–0,2 dl·g−1 in excellent yields. These polymers were soluble in polar aprotic solvents and both acidic and basic media. They began to lose weight at around 300°C in nitrogen under thermogravimetry.
Trans‐poly(butadiene‐co‐piperylene): Influence of temperature and molecular weight on bulk crystallization
Authors: De Chirico Aurelio
Published: April 2003

Bulk isothermal crystallization kinetics of a trans‐poly(butadiene‐co‐piperylene) sample (35 mol‐% of piperylene

Systematic name: 1,3‐pentadiene.

) and of its fractions were examined by dilatometry. Crystallization rates increase as crystallization temperature and molecular weight decrease. A solid/solid transition temperature, increasing with crystallization temperature, was observed. The nucleation free energy decreased with the crystallization temperature. This might be attributed to formation of less stable crystallites during the crystallization process.
Polystyrene as an inert medium in the synthesis of the styrene/divinylbenzene/acrylonitrile copolymers
Authors: Drăgan Stela , Nichifor Marieta , Petrariu Ioan
Published: April 2003

Samples of styrene/divinylbenzene/acrylonitrile macroporous copolymers were prepared, using polystyrene as inert medium. The initial viscosity average molecular weight of the polystyrene samples were: M̄v.i=87000, 98000, 117000 and 218000. The polystyrene samples with the initial molecular weights M̄v.i=87000 and M̄v.i=117000 were reused as inert media, for many times, until they lost their capacity to produce permanent porosity of the copolymers. The macroporous copolymers were characterized by their permanent porosity and volume swelling. If a polystyrene sample is used for many times, the molecular weight of the polystyrene removed (extracted) is gradually diminished and therefore the permanent porosity of the macroporous copolymers decreases step by step. The reasons responsible for this behaviour are:

during the copolymerization process a polystyrene with a smaller molecular weight is formed.

polystyrene parts of high molecular weights are included in the network structure of the macroporous copolymers.

The evidence for this was given by plotting the differential and integral molecular weight distribution curves for six samples of polystyrene.
Mechanismus der photopolymerisation des styrols, 1. Zur desaktivierung elektronisch angeregten styrols durch chemische konzentrations‐löschprozesse: Photooligomere und photopolymere
Authors: Kauffmann Harald Friedrich
Published: April 2003

Electronically excited styrene—in bulk or in concentrated solution—via intermolecular fluorescence self quenching processes undergoes a series of parallel and consecutive chemical reactions, leading to photooligomers and photopolymers. The oligomeric photoproducts, as shown by gas chromatography analysis, consist of dimers (M2) and trimers (M3) of styrene, whereby the quantity of M2 exceeds M3 by a factor of 20. The dimer fraction is built up of (a) 4 non olefinic cyclic C16‐hydrocarbons: cis‐1,2‐diphenylcyclobutane (c‐CB, 45–50 wt.‐%), trans‐1,2‐diphenylcyclobutane (tr‐CB, 8–10 wt.‐%), 1‐phenyl‐1,2,3,4‐tetrahydronaphthalene (1‐PhT, 7–9 wt.‐%), and 2‐phenyl‐1,2,3,4‐tetrahydronaphthalene (2‐PhT, 3–5 wt.‐%), (b) an open chain unsaturated compound–1‐vinyl‐2‐(2‐phenylethyl)benzene (VPEB, 5–7 wt.‐%), and (c) 5 highly unsaturated mono‐, bi‐, and/or tricyclic C16‐valence isomers (19–32 wt.‐%) which are considered to be the result of the participation of the aromatic benzene system in 1,2‐, 1,3‐ or 1,4‐photocycloaddition reactions, respectively. Among the numerous phototrimers, two saturated C24‐hydrocarbons were identified: 1‐phenyl‐4‐(1‐phenylethyl)‐1,2,3,4‐tetrahydronaphthalene (T1) and 2‐phenyl‐4‐(1‐phenylethyl)‐1,2,3,4‐tetrahydronaphthalene (T2). Under conditions where simultaneous thermal processes could be excluded (−20⩽T/°C⩽25), the presence of 1‐PhT, 2‐PhT, T1 and T2 gives strong evidence for the involvement of two 4π + 2π‐photointermediates, viz. 1‐phenyl‐1,2,3,8a‐tetrahydronaphthalene (1) and 2‐phenyl‐1,2,3,8a‐tetrahydronaphthalene (1′), which undergo two consecutive reactions: (a) a unimolecular, photo‐induced 1,3‐sigmatropic rearrangement (1‐PhT, 2‐PhT) and (b) a bimolecular, photo‐induced ene‐reaction with styrene as enophilic component (T1, T2). Because of the non‐concerted, stepwise nature of this photo‐ene‐process, the trimers have to be interpreted as the products of a cage reaction between two radical pairs |R1…R2| and |R1…R2′|. Their presence therefore gives strong evidence that the non‐concerted ene‐reaction is the most probable pathway for the production of the free radicals, which are responsible for the initiation of photopolymerization.
Einfluß einer orientierung der moleküle auf die kinetik der kristallisation von polyethylenterephthalat
Authors: Althen Gaby , Zachmann Hans Gerhard
Published: April 2003

Amorphous samples of poly(ethylene terephthalate) were oriented by drawing at 92°C to different drawing ratios as well as by cold drawing. The kinetics of isothermal crystallization was determined in the range from 70°C to 115°C. The orientation of the samples was measured by the birefringence before crystallization. With increasing orientation also the rate of crystallization increases and the Avrami exponent n decreases from 3 to 1. The density obtained at the end of the crystallization process almost is not affected by the orientation. The results also indicate that some sort of order occurs already during the orientation process. The results are discussed. The birefringence does not change monotonically during crystallization.