bluuebunny/crossref_metadata_2025 huggingface dataset:
Reaction of benzyl carbamates with formaldehyde. Resins from formaldehyde. 101
Authors: Takeuchi Shigeya , Kinoshita Masayoshi , Ko Keiun , Imoto Minoru
Published: April 2003

The reaction of p‐substituted benzyl carbamates (BC) with formaldehyde (F) was carried out in dioxane/water solution in the presence of potassium hydroxide yielding N‐methylol derivatives. Their structures were identified by elementary analysis, IR, and NMR spectra. The kinetic study was carried out using potassium hydroxide as a catalyst resulting the following rate equation.

The rate constants for the reaction of p‐substituted benzyl carbamates with formaldehyde fit HAMMETT's equation and the values of ρ were estimated to be +0.6 and +0.3 for lower and higher formaldehyde concentrations, respectively. The kinetics and the mechanism of the reaction are discussed.
Polychalkone III. Polymeranaloge reaktionen der Polychalkone mit hydrazinen
Authors: Oleinek Heinz , Zugrǎvescu Ioan
Published: April 2003

Es wird die polymeranaloge Reaktion zwischen Polychalkonen und Phenylhydrazin, die zu Polypyrazolinen führt, beschrieben. Die Polymeren werden durch Elementaranalyse, IR‐Spektren und Viskositätsmessungen charakterisiert.

Bei der vergleichenden Thermoanalyse zeigen sie eine bessere Wärmebeständigkeit als die entsprechenden Polychalkone.
Polymerization of methyl methacrylate in solution
Authors: Zafar M. M.
Published: April 2003

The polymerization of methyl methacrylate in solvents of different nature and viscosity, has been studied at 60°C using azobisisobutyronitrile as initiator. Kp and Ri have been determined by means of rate and molecular weight and assuming that Kt ≈ 1/ηmix. The propagation coefficient and the rate of initiation, both seems to be affected by the nature of the solvents.
On the existence of electrolysis in ionic polymerization conducted under an electric field
Authors: Tanner J. , Hornof V. , Funt B. L.
Published: April 2003

The experimental conditions employed for rate enhancements by field effects have been examined. An estimate of currents flowing in the systems has been made and the magnitude of electrolytic effects estimated. For living anionic systems, if the passage of electrolytic current is assumed to produce or destroy one living end per electron flowing, the magnitude of the electrolytic effect is significant and may range over 50% of the living end concentration for systems of high dilutions. The differences between electric field effects in living anionic and cationic polymerizations are discussed particularly with reference to the recent controversy over periodic field reversal experiments.
Multimerisation: Assoziation und aggregation. XI. Assoziation von Poly(methylmethacrylat‐co‐äthylenglykolmethylacrylat)
Authors: Vogt Peter , Elias Hans‐Georg
Published: April 2003

Äthylenglykolmethacrylat (EGMA) und Methylmethacrylat (MMA) wurden in Dioxan bei 75°C im Bereich zwischen 0 und 100% EGMA zu kleinen Umsätzen radikalisch copolymerisiert. Die durch Extrapolation auf die Konzentration Null erhaltenen scheinbaren Gewichtsmittel (Mw)extr der Molekulargewichtes hingen bei 25°C noch von der Natur des bei Lichtstreuungsmessungen verwendeten Lösungsmittels ab. Der für eine Probe erhaltene jeweils niedrigste Polymerisationsgrad wurde als das wahre Gewichtsmittel x̄w des Polymerisationgrades angesehen. Das Verhältnis (xw)extr/x̄w nahm in der Reihenfolge Dimethylformamid, Aceton, Dioxan jeweils mit steigendem Gehalt an Äthylenglykolmethacrylat‐Bausteinen zu. In Butanon sank dagegen dieses Verhältnis mit steigendem EGMA‐Gehalt der Copolymeren ab und wurde bei einem EGMA‐Gehalt von ca. 10 Gew.‐% gleich 1.
The crystal structure of polypivalolactone
Authors: Perego G. , Melis A. , Cesari M.
Published: April 2003

A detailed investigation on the crystal structure of polypivalolactone (PPL) has been performed by X‐ray diffraction technique. The dimensions of the monoclinic unit cell are : a = 9.05, b = 11.58, c = 6.03 Å; (fibre axis), β = 121.5°. The space group is P21/b. In a previous work CARAZZOLO proposed, on the basis of a rough approach, a (T2G2)2 chain model with a distortion of about 12° from all trans and gauche conformations, in addition to a statistical occurrence of enantiomorphous macromolecules in the crystal.

Although the (T2G2)2 conformation type has been confirmed, the model is not isodistorted, the distortion beeing related only to the COO and CH2C(CH3)2 bonds (16 and 19° respectively); in addition it is possible to exclude the statistical variance previously proposed.

The details of the conformation are discussed and compared with similar features of the crystal structure of poly(ethylene adipate).

A stabilization of this conformation by a preferred intramolecular arrangement of the main dipoles CO is suggested.
Asymmetric addition catalyzed by optically active polymers. III.
Authors: Ohashi Shin'ichi , Inoue Shohei
Published: April 2003

Asymmetric addition of lauryl mercaptan to various α.β‐unsaturated carbonyl and nitrile compounds was tried with optically active polymeric and low molecular weight amines as catalyst. In the asymmetric addition of lauryl mercaptan to methyl methacrylate and methyl isopropenyl ketone, remarkable diluent effect was observed in the case with polymer catalyst. Especially the effect of alcohols as an additive was very specific.
Vinyl polymerization by metal complexes. IV. Polymerization of vinyl monomers by copper(II)‐oligo(n)ethylene‐(n+1)amine systems
Authors: Inaki Yoshiaki , Ishiyama Masanobu , Takemoto Kiichi
Published: April 2003

Polymerization of vinyl monomers, particularly of acrylonitrile, was studied in the presence of copper(II)chloride, oligo(n)ethylene‐(n+1)amines as multidentate ligands, and carbon tetrachloride. The equimolar copper(II)‐oligo(n)ethylene‐(n+1)amine system could not initiate the polymerization of vinyl monomers. In the presence of excess amount of oligo(n)ethylene‐(n+1)amine, however, the polymerization was much accelerated. These facts suggest that the initiation process involved a reaction between copper(II)‐oligo(n)ethylene‐(n+1)amine complex with free oligo(n)ethylene‐(n+1)amine present in the reaction system.
Anionic polymerization of methacrylic esters. I. Stereoregularity
Authors: Junquera J. , Cardona N. , Figueruelo J. E.
Published: April 2003

In order to study the influence of cation, solvent and ester group on the content of stereoregular units of poly(alkylmethacrylates), methyl, ethyl and n‐butyl methacrylates have been polymerized at −70°C in dimethoxyethane and at −78°C in tetrahydrofuran using biphenyllithium, ‐sodium and ‐potassium as initiators. The poly(alkylmethacrylates) have been transformed into poly(methylmethacrylates) and their content of steric units was determined by NMR.

All the polymers are predominantly syndiotactic and show values of ρ (persistence ratio) close to the unity. The syndiotactic content seems to be enhanced by the cation in the following order : Li+ > Na+ > K+. The solvent does not play a common role, its effect depends on the cation/monomer system. Although the ester side group has not a pronounced stereodirecting effect it seems that syndiotactic positions are favoured in the following order: n‐butyl > ethyl ⋍ methyl. The results are discussed in terms of the two states mechanism of COLEMAN and FOX, and those states are identified as free ions and different types of ion pairs, since the presence of a common cation affects the content of stereoregular units of the polymer.
Synthèse et caractérisation de polystyrènes en étoile à trois branches
Authors: Herz Jean , Hert Marius , Strazielle Claude
Published: April 2003

La réaction de désactivation électrophile d'un polystyrène «vivant» monocarbanionique sur le tris(allyloxy)1.3.5‐triazine, conduit à la formation de molécules en étoile à trois branches dans lesquelles les branches sont liées aux trois atomes de carbone d'un hétérocycle triazine. La détermination des caractéristiques moléculaires de ces polymères par osmométrie, diffusion de la lumière, viscosimétrie et par chromatographie sur gel (GPC), montre que des molécules‐modèle de structure bien définie et de très faible polydispersité ont été obtenues. Les propriétés hydrodynamiques de ces polystyrènes en étoile sont étudiées et comparées aux prévisions théoriques.
The graph‐like state of matter. IV. Ring‐chain competition kinetics in a branched polymerisation reaction
Authors: Temple William B.
Published: April 2003

A kinetic scheme has been developed which accurately describes the kinetics of a simple branched polymerisation, including cyclisation reactions, up to a limited extent of reaction (∼25% conversion). The system adopted was an alternating copolymerisation of a 2‐functional and a 3‐functional monomer. Results were used to test the accuracy of the spanning‐tree approximation (see previous paper). As in the linear case, the approximation was found to give good agreement with the exact results.
Spontane polymerisation von 2‐vinylpyridin in gegenwart von polymethacrylsäure
Authors: Klein Christoph
Published: April 2003

Die spontane Polymerisation von 2‐Vinylpyridin in Gegenwart von Polymethacrylsäure in wäßriger Lösung wurde mit Polymethacrylsäuren verschiedener Taktizität untersucht. Die Polymerisationssysteme waren heterogen, wobei Poly(2‐vinylpyridin) und Polymethacrylsäure fast ausschließlich in der festen Phase gefunden wurden. Die Bruttopolymerisationsgeschwindigkeit hing nur sehr wenig von der Taktizität der Polysäuren ab. Anfallende Poly(2‐vinylpyridin)/Polymethacrylsäure‐Gemische konnten nur in stark saurem Milieu getrennt werden. Die abgetrennten Poly(2‐vinylpyridine) waren nach NMR‐spektroskopischen Messungen vorwiegend syndiotaktisch, die Taktizität hing jedoch nicht von der Taktizität der Polysäure ab.
Vinyl polymerization. 281. Radical polymerization of acrylonitrile initiated by tetramethyltetrazene and nucleic acid bases
Authors: Sugiyama Kazuo , Nakaya Tadao , Imoto Minoru
Published: April 2003

The polymerization of acrylonitrile initiated by the binary systems of tetramethyl‐tetrazene (TMT) and some nucleic acid bases, especially a TMT/adenine system, has been studied in dimethylformamide. The polymerization, initiated by the TMT/adenine system, was free radical in nature. The initial rate of polymerization was dependent on the square root of the concentrations of both TMT and adenine, and on the second power of the monomer concentration. The abnormal rate dependence on the monomer concentration could be explained. The overall energy of activation of the polymerization was found to be 21.5 kcal/mole over the temperature range of 55–75°C. The dimethylamino endgroup was incorporated in the polymer of styrene obtained by initiation with the above system, whereas the adenine group has never been detected. The TMT/adenine interaction in the absence of monomer was measured by a spectrophotometric method. These results were discussed in relation to a possible mechanism for the radical formation.
Vinyl polymerization. 283. Polymerization of acrylonitrile. Initiated by 1.4‐dimethoxycarbonyl‐1.4‐diphenyl‐1‐2‐tetrazene
Authors: Sugiyama Kazuo , Nakaya Tadao , Imoto Minoru
Published: April 2003

The polymerization of acrylonitrile (AN) initiated by 1.4‐dimethoxycarbonyl‐1.4‐diphenyl‐2‐tetrazene (DDT) was investigated in dimethylformamide (DMF) solution. The polymerization proceeds by a radical mechanism. The rate of polymerization is proportional to [DDT]0.63 and [AN]1.52. The apparent activation energy for the polymerization is 15.4 kcal. mole−1 within the temperature range of 65° to 85°C. The chain transfer constants of DDT and DMF were determined. A study was also undertaken on the kinetics of the thermal decomposition of DDT over the temperature range of 104° to 126°C. The kinetic data for the decomposition at 104°C are k1 = 6.0.10−6 sec−1, ΔH≠ = 31.3 kcal. mole−1, and ΔS≠ = −1.87 e. u., respectively. On the bases of these results, the polymerization mechanism is discussed.
Vinyl polymerization. 284. Polymerization of methyl methacrylate initiated by 4.4′‐diazidoazobenzene
Authors: Doiuchi Tooru , Nakaya Tadao , Imoto Minoru
Published: April 2003

The kinetics of the radical polymerization of methyl methacrylate (MMA) with 4.4′‐diazidoazobenzene (DAAB) as initiator was investigated in benzene solution. It was found that the initial rate of polymerization (Rp) can be expressed by the equation:

The overall activation energy for the polymerization was estimated to be 20.5 kcal/mole. The polymer obtained by the polymerization of MMA initiated by the above initiator was found to contain azobenzene fragment, presumably as endgroup. The thermal decomposition of DAAB was also studied in the temperature range 110 to 130°C. The overall activation energy of the decomposition of DAAB was 35.2 kcal/mole. The polymerization mechanism is discussed on the basis of these results.
Synthese und eigenschaften molekulareinheitlicher n‐paraffine bis zum C140H282
Authors: Heitz W. , Wirth Th. , Peters R. , Strobl G. , Fischer E. W.
Published: April 2003

Die Umsetzung von α,ω‐Dihalogenalkanen mit Natrium führt nach anschließender katalytischer Hydrierung zu einem Paraffingemisch mit diskontinuierlicher Molekulargewichtsverteilung. So enthält das aus 1.10‐Dibromdecan hergestellte Produkt nur Paraffine mit 10, 20, 30 usw. C‐Atomen, ein aus 1.20‐Dibromeicosan hergestelltes Produkt dagegen nur die Paraffine mit 20, 40, 60 usw. C‐Atomen. Diese Paraffingemische wurden gelchromatographisch in die molekulareinheitlichen Verbindungen zerlegt und Paraffine bis C140H282 isoliert.

Am Beispiel des C70H142 wurde die Temperaturabhängigkeit der Röntgenkleinwinkelstreuung gemessen. Aus Intensität und Lage der Langperiodenreflexe ließen sich die Änderungen von drei Strukturparametern ermitteln, die zur Charakterisierung der Lamellarstruktur geeignet sind.
Étude de la cristallisation des copolymères triséquencés poly‐ε‐caprolactone/polyoxyéthylène. I. Copolymères dont les séquences ont des longueurs très inégales
Authors: Perret Rémi , Skoulios Antoine
Published: April 2003

On a étudié la structure et la cristallisation de deux copolymères triséquencés poly‐ε‐caprolactone/polyoxyéthylène/poly‐ε‐caprolactone, l'un riche en caprolactone, l'autre en oxyde d'éthylène, dont les séquences sont toutes capables de cristalliser. Les techniques expérimentales utilisées sont la diffraction des rayons X aux petits et aux grands angles de BRAGG et la dilatométrie.

La structure de ces copolymères est lamellaire; elle correspond à l'empilement périodique de couches formées alternativement par les séquences POE et par les séquences PCL. Chaque couche est, elle‐měme, formée, suivant le cas, de sous‐couches comprenant la fraction amorphe et cristalline des polymères.

Le copolymère riche en PCL cristallise dans des lamelles dont l'épaisseur est indépendante de la température de cristallisation ou de recuit; il se comporte donc d'une manière similaire à un PCL homopolymère.

Le copolymère riche en POE fournit en revanche des lamelles dont l'épaisseur augmente avec la température, tant pour la cristallisation directe que pour le recuit; il se comporte donc pratiquement comme un POE homopolymère.

C'est donc la séquence majoritaire qui impose à l'ensemble du système son comportement et sa structure.
On the DSC fusion thermogram of semicrystalline polymers
Authors: Kamide Kenji , Yamaguchi Keiko
Published: April 2003

The characteristic fusion profiles of high polymers obtained by differential scanning calorimetry (DSC) are remarkably influenced by rearrangement and super‐heating of the semicrystalline structures during the heating process. Our intension is to correlate the above mentioned, phenomena with the molecular weight of the polymers. Highly isotactic polypropylene fractions and unfractionated polymers with molecular weights ranging from 5.7 · 103 to 1.6 · 106, were used for this purpose. With extremely low molecular weight polymers, the isothermally grown crystals revealed a distinct, double‐peaked fusion curve. The peak at the lower temperature was mainly assigned to the melting of the crystals originally present in the polymer whereas the second peak was due to the melting of the crystals originating from the recrystallization of the melt of the former. The isothermal rate of melting of the high molecular weight polymers, during annealing, is slow enough to be measured by DSC, and shows a prominent superheating effect. Consequently, a large contribution from the effect of rearrangement is seen in the thermograms of very low molecular weight polymers, but the effect of superheating is negligible. The above strongly suggest that the fusion curve obtained experimentally represents hardly the fine structures of the original polymer. The morphology of the crystals, especially the long loops, as well as the local viscosity around a molecular chain was speculated to be mainly attributable to the occurrence of rearrangement and/or superheating.
Vinyl polymerization. 290. Solvent effects on the decomposition of 1.4‐dimethoxycarbonyl‐1.4‐diphenyl‐2‐tetrazene
Authors: Sugiyama Kazuo , Nakaya Tadao , Imoto Minoru
Published: April 2003

The rate of thermal decomposition of 1.4‐dimethoxycarbonyl‐1.4‐diphenyl‐2‐tetrazene (DDT) has been measured in various solvents by UV spectroscopy. The rate measurements were carried out over a temperature interval from 65 to 85°C. The activation parameters have been calculated from the dependence of the rate constants on the temperature. On the basis of the kinetic data, the influence of the solvent on the decomposition of DDT was discussed. In this connection the solvent effect on the rate of polymerization of styrene initiated by DDT was also examined.
Radiolyse von polyisopren mit hohem gehalt an 1.2‐ und 3.2‐einheiten
Authors: Katzer Hans , Heusinger Helmut
Published: April 2003

Die Radiolyse von Polyisoprenen mit hohem 1.2‐ und 3.4‐Anteil, bei denen die Doppelbindungen in den Seitenketten sind, wurde untersucht.

Zur Festlegung der Veränderungen wurden die Molekulargewichtszunahme im Bereich vor der Gelbildung, die Sol‐Gel‐Fraktionen im Gel‐Bereich, die Abnahme der Doppelbindungen, die Bildung der Diene, die Struktur und die Konzentration der Radikale sowie die Bildung von H2 und CH4 bestimmt.

Die Ergebnisse der Sol‐Gel‐Messungen in Abhängigkeit von der Dosis zeigten, daß bei diesen Polymeren die Vernetzung über eine Kettenreaktion verläuft. Die kettenstartende Spezies wird mit einem G(S)‐Wert von durchschnittlich 2,5 gebildet, die Reaktionskette führt im Mittel zu 4 vernetzten Molekülen. Beide Werte sind etwas vom Molekulargewicht abhängig.

Auf Grund der Vernetzungen ist ein G‐Wert für die Doppelbindungsabnahme von etwa 10 zu gwarten, man findet aber IR‐spektroskopisch G(–db) = 130. Der Unterschied kann dadurch erklärt werden, daß neben intermolekularen Vernetzungen auch intramolekulare Cyclisierungen auftreten. Weiterhin wurde der Einfluß der Dosisleistung, der Bestrahlungstemperatur und verschiedener Additiva (Luft, Anthracen, Hydrochinon) auf die Vernetzung bestimmt.

Die aus unseren Untersuchungen gewonnenen Ergebnisse sprechen für einen kationischen Kettenmechanismus, der im einzelnen diskutiert wird. Hierin unterscheiden sich Polyisoprene mit hohem 1.2‐ und 3.4‐Anteil grundsätzlich von 1.4‐Polyisoprenen, bei denen pro Vernetzung mindestens eine Ionisation oder Anregung benötigt wird („konventionelle”︁, strahlenchemische Vernetzung).
Copolymere aus Vinylhalogeniden und olefinen. III. IR‐spektroskopische Sequenzanalyse an Vinylchlorid/Isobuten‐Copolymeren und Bestimmung der Copolymerisationsparameter aus den gemessenen Diadenkonzentrationen
Authors: Brück Dieter , Hummel Dieter O.
Published: April 2003

In der vorliegenden Arbeit wurden aus den IR‐Spektren der Vinylchlorid/Isobuten‐Copolymeren die Bruttozusammensetzung der Copolymeren, die relative Häufigkeit der Diaden und die mittleren Sequenzlängen experimentell bestimmt. Die durch Auswertung des δ(CH2)‐ und des ρ(CH2)‐Bandenkomplexes erhaltenen Werte zeigten eine gute Übereinstimmung mit solchen, die mit Hilfe der Copolymerisationstheorie berechnet wurden. Die Copolymerisationsparameter des Systems wurden aus den Diadenkonzentrationen ermittelt.
Über die inhibierung radikalischer polymerisationen durch aromatische hydrazyle. 2. inhibierung der styrolpolymerisation
Authors: Braun Dietrich , Peschk Günter
Published: April 2003

α,α‐Diphenyl‐β‐[2,4,6‐tris(methoxycarbonyl)‐phenyl]‐hydrazyl (DPTH), α,α‐Diphenyl‐β‐(2,4,6‐tricyanophenyl)‐hydrazyl (DPTCH) und α,α‐Diphenyl‐β‐pentaphenylcyclopentadienyl‐hydrazyl (DPCPDH) sind Inhibitoren der radikalischen Polymerisation von Styrol. Im Gegensatz zu nitrogruppenhaltigen Hydrazylen wie α,α‐Diphenylpikrylhydrazyl bewirken sie eine echte Induktionsperiode, in der die Hydrazyle verbraucht werden; die anschließende Polymerisation wird nicht durch Folgeprodukte des Inhibitors beeinflußt.

Die mit DPTH erhaltene Induktionszeit ist proportional der verwendeten Inhibitor‐konzentration und wird durch Luftsauerstoff nicht verändert. DPTCH reagiert dagegen in Gegenwart von Sauerstoff sehr rasch mit Styrol, so daß hier mit und ohne Luft unterschiedliche Induktionszeiten erhalten werden. DPTH eignet sich auch zur Bestimmung der Ausbeute an startwirksamen Radikalen beim Zerfall von Azoisobutyronitril in Styrol.
Ring‐opening polymerization of cyclic compounds with bifunctional groups. V. Polymerization of 7‐oxo‐4‐phenyl‐1,4‐azaphosphepane (phospha‐caprolactam)
Authors: Ogata Naoya , Saito Seiichiro
Published: April 2003

7‐Oxo‐4‐phenyl‐1,4‐azaphosphepane (II) (phospha‐caprolactam) and its 3,5‐tetramethyl derivative (IV) containing an amide group and a phosphorus atom in the same ring, have been synthesized and polymerized in the presence of various catalysts. II polymerized with Al(C2H5)2Cl or SnCl4 as catalysts to give polyamide of low molecular weight, whereas IV did not polymerize with satisfactory results. On the other hand, the copolymerization of the tetramethyl substituted “phospha‐caprolactam” IV with other cyclic compounds including lactams, lactones or cyclic ethers took place in the presence of cationic catalysts.
Optically active copolymers of l‐menthyl methacrylate and l‐menthyl vinyl ether
Authors: Matsuzaki Kei , Sugimoto Toshio
Published: April 2003

Optically active copolymers of l‐menthyl methacrylate or l‐menthyl vinyl ether with maleic anhydride or N‐(p‐tolyl)maleimide were prepared. The optical activity of the co‐polymers of l‐menthyl methacrylate was almost proportional to the contents of l‐menthyl methacrylate units in the copolymers, and after removal of the optically active side groups by hydrolysis, the optical activity disappeared. On the contrary, the optical activity of the copolymers of l‐menthyl vinyl ether was considerably lower than the proportionality, and after removal of the side groups, optical activity opposite to the parent copolymers was observed. The cause for asymmetric induction was ascribed to the rigidity of the polymer chain.
Polymérisation de dérivés du cyclopropane. IV. Polymérisation du bicyclopropyle
Authors: Pinazzi Chr. P. , Legeay G. , Brosse J. C.
Published: April 2003

Le bicyclopropyle, isomère du diméthyl‐2,3 butadiène‐1,3, mis en présence d'acides de LEWIS ou de divers catalyseurs de ZIEGLER‐NATTA conduit à des polymères formés d'un enchainement de motifs monocyclohexbniques, comparables à ceux qui sont obtenus par cyclisation du polyisoprbne‐1,4. Les températures d'amorçage peuvent être relativement faibles et les taux de conversion presentent un maximum pour les temperatures voisines de 50°C. Aux temperatures plus Clevees, les taux de conversion dhcroissent du fait même de la nature du monomere. Le mecanisme de polymerisation prockde par ouverture des deux cyclopropanes, suivie d'une riaction de cyclisation entre deux unitis monomères.

En presence du couple TiCl4/Et3Al, la polymerisation s'effectue en partie par ouverture d'un seul cyclopropane : un polymhre lineaire possedant des groupements cyclopropaniques en chafne laterale est alors obtenu.
Polymérisation de diènes conjugués aux hautes pressions. IX. Polymerisation de l'isoprène en presence de HI
Authors: Abdi‐Oskoui Hossein , Jenner Gérard , Brun Claude
Published: April 2003

L'action de HI dans la polymérisation de lisoprbne est très sensible sous pression et dépend de la concentration en eau dans le milieu rCactionnel. En l'absence d'eau, on observe une dimerisation cyclique (formation de limonbne). La présence d'eau augmente la vitesse de rdaction au profit du polymbre. La structure des polymbres n'est pas affectée par les variations de concentration en eau, seule la pression apporte des modifications à la structure en rdduisant l'addition en 1,4 cis et en favorisant de ce fait les unitds 1,4 trans. La dimCrisation et la polymdrisation se font probablement selon d e w mdcanismes differents.
On the bulk polymerization of vinyl chloride
Authors: Ugelstad J. , Fløgstad H. , Hertzberg T. , Sund E.
Published: April 2003

In continuation of our investigations on the kinetics and mechanism of bulk and emulsion polymerization of vinylchloride, the mechanism of bulk polymerization is still further elucidated. A simple approximative method which in the preceding paper was only suggested but not evaluated in detail is given a more comprehensive discussion and it is shown that the method may describe the significant experimental results obtained in bulk polymerization of vinyl chloride. A correction to the more elaborate methods applied in the preceding paper is given.
On the orthorhombic to hexagonal phase transformation in polyethylene single crystals
Authors: Thomas E. L. , Sass S. L.
Published: April 2003

The orthorhombic to hexagonal transformation in polyethylene single crystals was examined at room temperature and 110°C using electron diffraction. The transformation involves an anisotropic lattice expansion and the formation of a projected 6‐fold symmetric atomic potential on a plane normal to the chain axis. The continuous transformation to the hexagonal phase at low temperatures was shown to occur primarily by crosslinks formed between chains during irradiation. At high temperatures, following nucleation of the hexagonal phase by an initial electron dose, further growth of the hexagonal phase without irradiation is believed to occur by the introduction of chain ends (which provides for easy chain rotation) into the crystal interior during annealing.
Solvent effects in radical copolymerization. IV. N‐methyl acrylamide
Authors: Leoni Alvaro , Franco Simone , Saini Guido
Published: April 2003

The influence of different solvents on the copolymerization behaviour of N‐methyl acrylamide with styrene and methyl methacrylate has been investigated. The calculated relative reactivities of N‐methyl acrylamide towards both the polystyryl and poly(methyl methacrylyl) radicals (1/r2) are practically unaffected by the reaction medium; on the contrary, the relative reactivities of both styrene and methyl methacrylate monomers towards the poly(N‐methyl acrylamide) radical (1/r1) are remarkably influenced by the reaction solvents. A comparison both with unsubstituted and disubstituted acrylamides polymerized under the same conditions has been made.
Vinyl polymerization. 294. Decomposition of tetramethyltetrazene in the presence of p‐substituted benzyl chlorides
Authors: Sugiyama Kazuo , Hatanaka Hideo , Nakaya Tadao , Imoto Minoru
Published: April 2003

A study was made of the polymerization of acrylonitrile in dimethylformamide (DMF) initiated by the binary systems of tetramethyltetrazene (TMT) and p‐substituted benzyl chlorides. The polymerization rate increased linearly with the σ‐constants of substituents as electron‐releasing groups were introduced to the phenyl ring of benzyl chloride. In order to elucidate the initiation mechanism of the polymerization, a kinetic investigation was also undertaken of the decomposition of TMT in the presence of p‐substituted benzyl chlorides in DMF. The decomposition rate was first‐order in TMT and first‐order in p‐substituents benzyl chloride. The decomposition rate also increased with the σ constants of substituents as electron‐releasing groups were introduced. On the basis of the results, the initiation mechanism for the polymerization was discussed.
Aqueous polymerization of methacrylamide initiated by the redox system K2S2O8/ascorbic acid
Authors: Misra G. S. , Gupta C. V.
Published: April 2003

The polymerization of methacrylamide initiated by the redox system K2S2O8/ascorbic acid has been studied at 35 ± 0,2°C under the influence of atmospheric oxygen. The molecular oxygen autocatalyses the polymerization rate. The rate of polymerization is independent of the activator (ascorbic acid) concentration within the range 2,83 · 10−3 to 11,3 · 10−3 mol · l−1, this does not hold below or above the given concentration range. The rate varies linearly at low monomer concentration (up to 17,76 · 10−2 mol · l−1). The catalyst exponent decreases from nearly unity (0,94) to 0,57 with increasing concentration of the catalyst probably due to participation of primary radicals in the termination of growing chain. The initial rate is not changed by the addition of a strong acid (H2SO4) within the range 15 · 10−5 to 30 · 10−5 mol · l−1. With the activator (ascorbic acid) alone, an optimum is observed within the pH range 2,9–3,5. The initial rate and the limiting conversion increases with increasing polymerization temperature. The overall energy of activation as calculated from the ARRHENIUS plot has been found to be 16,0 kcal.mol−1 within the temperature range 30–45°C.

Organic solvents (water miscible only) and small amounts of neutral salts, (KCl, Na2SO4) depress the initial rate and the maximum conversion. The addition of small amounts of catalysts like Cu2⊕, Mn2⊕, Agoplus; increases the initial rate but no appreciable increase in the limiting conversion is observed.
Lösungseigenschaften von äthylcellulose. Vergleichende bestimmungen von molekulargewichten und zweiten virialkoeffizienten mittels osmose, lichtstreuung und sedimentation/diffusion
Authors: Sütterlin N. , Meyerhoff G.
Published: April 2003

Es wurden osmotische und Lichtstreuungsmessungen an Äthylcellulose in Aceton, Äthylacetat, Butanol‐(2), n‐Butylchlorid und Benzol (nur Osmose) ausgeführt und die Ergebnisse in einigen Fällen mit Hilfe der Sedimentation/Diffusion kontrolliert. Durch Vergleich der verschiedenen Meßmethoden konnten die von Gelen unbeeinflußten Meßergebnisse gegen die durch Gele verfälschten Werte abgegrenzt werden.

Die osmotisch und hydrodynamisch bestimmten A2‐Werte sind hoch im Vergleich zu denen von Vinylpolymeren. Im Gegensatz dazu steht der niedrige Exponent ε der Trägheitsradius‐Molekulargewichtsbeziehung

der sich für negative Exponenten ε nur durch Geleinfluß deuten läßt. für die zweiten Virialkoeffizienten wurde eine nur wenig ausgeprägte Lösungsmittelabhängigkeit beobachtet.
Study of organized structures of polystyrene/polybutadiene/polystyrene block copolymers
Authors: Douy André , Gallot Bernard
Published: April 2003

Using both monochromatic low angle X‐ray scattering and electron microscopy, we have shown that polystyrene/polybutadiene/polystyrene (SBS) block copolymers exhibit, in the presence of a preferential solvent for one block, liquid crystalline structures, before and after polymerization of the solvent. These structures are of three types: hexagonal, lamellar and reversed hexagonal.

We have shown that the structural type adopted by SBS copolymers is governed by the composition of the copolymer. Inside the domain of stability of each structure, we have studied the variation of the structural parameters with different factors: concentration and nature of the solvent, composition and molecular weight of the copolymer, temperature, polymerization of the solvent.

The properties of SBS and BSB copolymers are compared.
The direct conversion of 6‐aminocaproic acid vapor into polymer single crystals
Authors: Macchi E. M.
Published: April 2003

Specimens of Nylon 6 obtained by reaction of the monomer in the vapor phase onto surfaces of crystalline substrates are investigated by electron microscopy and electron diffraction.

The specimen is found to consist of lamellar spherulites of Nylon 6, as it was already reported, and a small proportion of single crystals displaying the structure known as the Gamma‐form.
Über die polykondensation von isothiocyanatocarbonsäuren, DTE‐aminosäuren und 5‐oxo‐2‐thioxo‐oxazolidinen (2‐thioxo‐oxazolidonen‐(5))
Authors: Kricheldorf Hans R.
Published: April 2003

Aliphatische wie aromatische Isothiocyanatocarbonsäuren werden in hoher Reinheit und guten Ausbeuten aus ihren Trimethylsilylestern gewonnen; dabei cyclisieren die 2‐Isothiocyanatocarbonsäuren sofrt zu den isomeren in 4‐Stellung substituierten 5‐Oxo‐2‐thioxo‐oxazolidinen (2‐Thioxo‐oxazolidonen‐(5)). Aliphatische und aromatische Isothiocyanatocarbonsäuren lassen sich über 150°C polykondensieren, in Gegenwart basischer Katalysatoren bereits bei Raumtemperatur, wobei unter Abspaltung von COS Polyamide entstehen. Bei 3‐ und 4‐Isothiocyanatocarbonsäuren verhindert die Cyclisierung der Isothiocyanat‐Endgruppe bzw. die Bildung von γ‐lactamen das Zustandekommen höherer Polymerisationsgrade. 5‐Oxo‐2‐thioxo‐oxazolidine lassen sich ebenfalls, thermisch oder basisch katalysiert, durch ionische, ringöffnende Polymerisation in Polypeptide überführen. DTE‐Aminosäuren bilden primär die entsprechenden Isothiocyanatocarbonsäuren, deren Verhalten den weiteren Reaktionsverlauf bestimmt.
Polymerization of methyl methacrylate with alkyllithium in the presence of N,N,N′,N′‐tetramethylalkylenediamines or ω‐dimethylaminoalcohols as catalysts
Authors: Matsuzaki Kei , Nishida Yoshiki , Kumahara Hiromi , Miyabayashi Toshio , Yasukawa Tamio
Published: April 2003

Methyl methacrylate was polymerized with alkyllithium in the presence of N,N,N′,N′‐tetramethylalkylenediamines or ω‐dimethylaminoalcohols as catalysts. The effects of the catalysts on the stereoregularity and the yield of the polymers were investigated. The presence of N,N,N′,N′‐tetramethylethylenediamine or 2‐dimethylaminoethanol resulted in a decrease of yield and isotacticity of the polymers, especially in toluene. The decrease was attributed to the formation of stable five‐membered ring chelates in the reaction of alkyllithium with N,N,N′,N′‐tetramethylethylenediamine or 2‐dimethylaminoethanol.
Kinetic effects of surfactants on a polymer reaction in a nonaqueous system: Nucleophilic substitution of poly(vinyl chloride) with the azide ion
Authors: Takeishi Makoto , Kawashima Riichiro , Okawara Makoto
Published: April 2003

Cationic surfactants such as laurylpyridinium chloride and tetrabutylammonium chloride catalyze the nucleophilic substitution of poly(vinyl chloride) with sodium azide in tetrahydrofuran, dioxane and cyclohexanone in which sodium azide is insoluble. An anionic surfactant, sodium laurylbenzenesulfonate, does not catalyze the reaction. It was assumed that a quarternary cation exchanges a chloride ion for an azide ion and then transfers it to the reaction site of poly(vinyl chloride) through the solvent. The reaction of poly(vinyl chloride) with laurylpyridinium azide was also investigated, and a saturation phenomenon in the relationship between the rates and the concentrations of laurylpyridinium azide was observed. The kinetic data are discussed in terms of an “adsorption” of the quarternary salts on a poly(vinyl chloride) chain.
Methods for treating data of excluded volume effects in dilute polymer solutions
Authors: Nakata Mitsuo
Published: April 2003

A method for estimating the free‐energy parameter B appearing in the excluded volume parameter z defined by z=(4π)−3/2B(M/〈s20〉)3/2M1/2 was proposed based on the semiempirical equation of STOCKMAYER N0B/2A2 = 1 + Sz/a3 (S = 2,865) for the second virial coefficient A2, where N0 is the AVOGADRO number and a is the expansion factor. When the temperature dependence of B is given by B = B0(1−Ω/T) the definition of z and the STOCKMAYER equation yield the relation

The plot of (1−Ω/T)/A2 versus M2(1−Ω/T)〈s2〉−3/2 due to this equation was made for the existing experimental data on the theta solvent and was found to give a straight line. The values of B0 and S obtained by this plot agreed with the value determined by BERRY's method and the theoretical value S = 2,865 respectively. In order to investigate the behaviour of a at small z, the data of a near the theta temperature were analyzed with an approximate equation a5 ‐ a2 = 1,914z which fits to the perturbation theory and to the YAMAKAWA‐TANAKA equation of a in the region 0<z<5.
Korrektur der kollimationseinflüsse bei röntgenweitwinkelmessungen
Authors: Glatter Otto
Published: April 2003

Die bei Röntgenweitwinkelmessungen mit Lochblendensystem, zylindrischem Präparathalter und spaltförmigem Detektor entstehenden Kollimationseinflüsse werden mathematisch erfaßt. Die so erhaltene Integralgleichung wird unter Verwendung orthonormierter Funktionensysteme gelöst. Die Lösungskurve wird zur Fehlerkontrolle nach einer getrennten und von dem Lösungsverfahren unabhängigen Methode rückintegriert. An Hand einer experimentell bestimmten Streukurve wird die Leistungsfähigkeit des Verfahrens gezeigt. Sämtliche Rechnungen wurden mit einem eigens erstellten FORTRAN‐IV‐Programm durchgeführt.
Thermal degradation of copolymers of methyl methacrylate and butyl acrylate, 2. Identification and analysis of volatile products
Authors: Grassie N. , Fortune J. D.
Published: April 2003

The volatile products of thermal degradation of copolymers of methyl methacrylate and butyl acrylate covering the entire composition range have been identified. 1‐Butene and carbon dioxide are the main gaseous products. Other products, methane, ethane, propane, butane, ethylene, propylene, cis and trans 2‐butene, hydrogen and carbon monoxide are also present in very small amounts which tend to increase with the butyl acrylate content of the copolymer. The liquid products are butanol, methyl methacrylate, butyl acrylate and butyl methacrylate.

Products have been estimated quantitatively for all the copolymers at intervals during the course of the reaction and detailed mass balance tables drawn up.

The yields of carbon dioxide and 1‐butene and the molar ratio of carbon dioxide to 1‐butene all increase with increasing acrylate content of the copolymer. Methyl methacrylate is the only liquid product from high methacrylate copolymers. Butyl acrylate and methacrylate begin to appear in 16,3 mole‐% butyl acrylate copolymer although butanol is still absent. From high acrylate copolymers butanol is the only liquid product.
Addition of chlorine and nitrogen dioxide to linear polybutadienes reaction mechanism
Authors: Royo Joaquín , González Luis , Ibarra Luis , Barbero Miguel
Published: April 2003

The reaction of chlorine or nitrogen dioxide with polybutadienes consists mainly in their addition to the double bonds of the polymer, but it is often followed by a number of secondary reactions, such as crosslinking and cis‐trans isomerization.

The effects of polymer microstructure, nature of the solvent, solution concentration, temperature, and various additives, are studied. To explain the experimental facts several reaction mechanisms are proposed.

The chlorination reaction is thought to follow an ionic and radical mechanism simultaneously. The former, which is always predominant, gives only soluble addition products without secondary reactions, whereas the latter can give rise to crosslinked and isomerized products, besides the addition product. Under certain experimental conditions the radical reaction can be avoided and only soluble addition products are obtained.

The reaction with nitrogen dioxide is predominantly of radical character, and consequently it is always followed by isomerization and crosslinking reactions. Only under special conditions these ancillary reactions can be avoided.
The interaction between polymerization initiators and inhibitors in solution. III. The reaction of benzoyl peroxide with 2,5‐dichloro‐1,4‐benzoquinone and 2,3,5,6‐tetrachloro‐1,4‐benzoquinone (chloranil) in chlorobenzene
Authors: Yassin A. A. , Rizk N. A. , Ghanem N. A.
Published: April 2003

The reaction of benzoyl peroxide with 2,5‐dichloro‐1,4‐benzoquinone and 2,3,5,6‐tetrachloro‐1,4‐benzoquinone (chloranil) in chlorobenzene was studied by isolation and identification of the reaction products.

In dilute solution (0,02 mol peroxide/dm3), both phenyl and benzoyloxy radicals interact with 2,5‐dichloro‐1,4‐benzoquinone to form the corresponding quinonoid derivatives by substitution of hydrogen atoms in the quinone nucleus. Chloranil does not react under these conditions.

In concentrated solution (0,5 mol peroxide/dm3), both 2,5‐dichloro‐1,4‐benzoquinone and chloranil are attacked by radicals of the spontaneous as well as the induced decomposition of the peroxide. Aryl radicals (but not benzoyloxy radicals) can substitute only one chlorine atom of the chloranil molecule. The difficulty is due to the steric hindrance of the chlorine atoms and the instability of the radical intermediate. This probably accounts for the tendency of chloranil to react with polymeric radicals through O‐ rather than C‐atoms.
Reaktionskinetik und gleichgewichtsumsätze bei der PF5‐initiierten homopolymerisation von tetrahydrofuran in 1,2‐dichloräthan
Authors: Hoene Richard , Reichert Karl‐Heinz W.
Published: April 2003

Die kationische Polymerisation von Tetrahydrofuran in 1,2‐Dichloräthan mit Phosphorpentafluorid also Initiator wurde mittels gaschromatographischer Bestimmung des Monomergehaltes unter reaktionskinetischen und thermodynamischen Gesichtspunkten untersucht.

Kinetische Versuche ergaben, daß die Polymerisationsgeschwindigkeit nicht linear mit der Initiatorkonzentration zunimmt. Der Einfluß der Initiatorkonzentration auf die Polymerisationsgeschwindigkeit nimmt vielmehr mit wachsender Initiatorkonzentration ab, was auf die Anwesenheit von Solvatationsgleichgewichten der aktiven Spezies zurückgeführt wird. Die Aktivierungsenergie der Polymerisation in Lösung wurde nach ARRHENIUS zu 15,2 kcal/mol bestimmt.

Durch Messung der Temperaturabhängigkeit der Gleichgewichts‐Monomerkonzentrationen wurden die thermodynamischen Größen ΔHp und ΔS0p und die Ceiling‐Temperaturen bei zwei verschiedenen Ausgangs‐Monomerkonzentrationen ermittelt. Die Gleichgewichts‐Monomerkonzentrationen liegen in Lösung höher als bei der Polymerisation in Substanz. Infolgedessen werden für die gewählten Ausgangs‐Monomerkonzentrationen in Lösung Ceiling‐Temperaturen beobachtet, die um 20–25°C tiefer liegen als die diesen Gleichgewichts‐Monomerkonzentrationen entsprechenden Temperaturen der Substanzpolymerisation. Für die Abhängigkeit der thermodynamischen Größen vom verwendeten Lösungsmittel werden Solvatationseffekte verantwortlich gemacht.

Weiterhin kann aus den Ergebnissen entnommen werden, daß im Bereich der Ceiling‐Temperatur die thermodynamischen Größen geringfügig vom Polymerisationsgrad abhängen.
The crystal structure of polylauryllactam (nylon 12)
Authors: Cojazzi Gianna , Fichera Annamaria , Garbuglio Carmine , Malta Viscardo , Zannetti Roberto
Published: April 2003

The crystal structure of nylon 12 was determined from the X‐ray diffraction patterns of uniaxially oriented specimens. The unit cell is monoclinic (pseudo‐hexagonal) with the following dimensions: a = 4,79 Å, b = 31,9 Å (fiber axis), c = 9,58 Å, β = 120°. There are four monomeric units in the unit cell and the space group is P21/c. The structure presents a distortion of the amide group from the planar chain conformation and it is rather similar to γ‐nylon 6. The hydrogen bond length is about 2,80 Å and the molecular packing is characterized by alternate, “up and down”, highly disordered sheets of parallel chains, linked by hydrogen bonds. The agreement between observed and calculated intensities has been improved by introducing a statistical disorder.
Polyethylene ionomers. The effect of annealing
Authors: Marx Curtis L. , Cooper Stuart L.
Published: April 2003

The effect of annealing on the morphological structure and properties of a poly(ethylene‐co‐methacrylic acid) ionomer is discussed. The density of samples annealed at different temperatures was measured and compared with densities calculated from calorimetry measurements assuming additivity of component volumes. At intermediate annealing temperatures, densities calculated from calorimetry are higher than densities experimentally measured. Also, at intermediate annealing conditions the X‐ray scattering associated with separation of ionic groups changes, and the multiple DSC melting endotherms merge into a single endotherm. These effects are thought to be caused by a thickening of polyethylene lamellae to a uniformly large fold distance which causes strain of the non crystallizable polymer segments and void formation.
Der aufbau einiger homologer reihen von hydroxyphenylenmethylen‐verbindungen und ihr schmelzverhalten
Authors: Kämmerer Hermann , Niemann Wilhelm
Published: April 2003

Will man das Schmelzverhalten von Novolaken voraussagen, dann ist es notwendig, die Eigenschaften der Hydroxyphenylenmethylen‐Verbindungen, früher als phenolische Mehrkernverbindungen bezeichnet, zu kennen, welche im Novolak enthalten sind. Daher wurden zur Ermittlung von Struktur/Eigenschaft‐Beziehungen einige homologe Reihen von Hydroxyphenylenmethylen‐Verbindungen hergestellt und ihr Schmelzverhalten untersucht. Dabei stellte sich heraus, daß das Schmelzverhalten der Hydroxyphenylenmethylen‐Verbindungen, das von Endgruppen und vermutlich konformativen Faktoren beeinflußt wird, verwickelt und weitgehend ungeklärt ist. Der Aufbau der streng homologen Hydroxyphenylenmethylen‐Verbindungen (3. Reihe) erfolgte auf zwei verschiedenen Synthesewegen. Außer Elementaranalyse und Molekulargewichtsbestimmung dienten zur Charakterisierung der neu hergestellten Verbindungen die Derivate, die durch vollständige Acetylierung aller phenolischen Hydroxylgruppen im Molekül erhalten wurden.
On the absence of stereoselectivity in the stereospecific polymerization of racemic 5‐methyl‐1‐heptene and 2‐methylbutyl vinyl ether
Authors: Chiellini Emo , Marchetti Massimo
Published: April 2003

Stereoregular polymers of racemic 5‐methyl‐1‐heptene (I) and 2‐methylbutyl vinyl ether (II), obtained by isospecific polymerization, when supported on poly[(S)‐3‐methyl‐1‐pentene](poly[sec‐butylethylene]) and on poly(L‐dilactide)(poly[L‐oxyethylidencarbonyl]) respectively give, by elution with solvents, optically inactive fractions.

On the contrary, optically inactive mixtures of equimolar amounts of stereoregular poly‐[(S)‐] and poly[(R)‐5‐methyl‐1‐heptene] (poly[(3‐methylpentyl)‐ethylene]) as well as of poly[(S)‐] and poly[(R)‐2‐methylbutyl vinyl ether] (poly[(2‐methylbutoxy)ethylene]), can be separated under the same experimental conditions into fractions having optical activity of opposite sign.

Even if the efficiency of the last separation is not very high (∼20%), the obtained results indicate that the polymeric products from racemic 5‐methyl‐1‐heptene and 2‐methylbutyl vinyl ether can be considered as random copolymers of the two enantiomers.

The comparable cristallinity of polymers from the above racemic monomers and from the corresponding optically active ones must be attributed to an indistinguishable arrangement of R and S monomeric units in the crystalline lattice.
Syntheses and reactions of functional polymers, 74. Syntheses of poly[1‐methyl‐1‐(5‐oxo‐4,5‐dihydro‐1,3,4‐oxadiazol‐2‐yl)‐ethylenes]
Authors: Endo Takeshi , Inoue Takeshi , Okawara Makoto
Published: April 2003

2‐Isopropenyl‐5‐oxo‐4,5‐dihydro‐1,3,4‐oxadiazoles (II) were prepared by the reaction methacrylohydrazides (I) with phosgene and their abilities for polymerization and copolymerization were investigated. The monomer reactivity ratios were determined in bulk polymerization. The polymers obtained were soluble in dimethylformamide and dimethylsulfoxide, but insoluble in common organic solvents. Some properties of these polymers were examined.
Polychalkone, IV. Gaschromatographisch‐pyrolytische untersuchungen wärmebeständiger polychalkone
Authors: Caşcaval C. N. , Oleinek Heinz , Zugrăvescu Ion , Schneider I. A.
Published: April 2003

In der vorliegenden Arbeit werden aus gaschromatographisch‐pyrolytischen Untersuchungsergebnissen einige Aussagen über die Wärmebeständigkeit und Struktur von Polychalkonen abgeleitet. Es zeigt sich, daß die Abschwächung der Elektronenwechselwirkung durch Unterbrechung der Konjugation des π‐Elektronensystems in der Hauptkette der Makromoleküle sich in den erhaltenen Chromatogrammen widerspiegelt.