bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular weight distribution studies, 2. Radiation‐induced polymerization of solid α‐methylstyrene
Authors: Chawla Attar S. , Huang Robert Y. M. 
Published: April 2003

AbstractThe radiation‐induced post ‐ and “in‐source” solid state polymerizations (the polymerizations occurred after and during the γ‐irradiation, resp.) of α‐methylstyrene were studied. Post‐polymerizations studied at −30°C, occurred only in pure and “dry” monomer. At a constant initial radiation dose of 2,5 Mrad (2,5.104J/kg), the rate of polymerization increased, although slightly, with increasing conversion. With increasing initial radiation dose of up to 7,4 Mrad (7,4.104J/kg) and post‐polymerized for 8 h, resp., the percentage of polymer yield per unit radiation dose decreased with increasing conversion. The GPC chromatograms of the polymer samples obtained showed a peak at 27,4 elution counts resulting from ionic polymerization and a shoulder at 29,0 counts from free radical polymerization.In the case of the “in‐source” polymerization, studied at −30 and −40°C, the “wet” monomer yielded rates of polymerization lower than those from “dry” monomer. GPC analysis of the polymer samples obtained at −40°C from both “dry” and “wet” monomer showed bimodal distributions, the higher molecular weight peak resulting from ionic polymerization. At increased conversions, the positions of both GPC peaks remained unchanged, whereas the heights and hence the ionic and free radical polymerization contribution changed, the ionic contribution decreasing. At −30°C polymerization temperature only one peak at 27,3 elution counts resulting from ionic polymerization was obtained.
Hypochromism of poly(N‐vinylcarbazole) in solution
Authors: Tsuchihashi Nobuaki , Enomoto Takamichi , Tanikawa Kiyoshi , Tajiri Akio , Hatano Masahiro 
Published: April 2003

AbstractAbsorption spectra were measured for poly(N‐vinylcarbazole) (PNVC), fractionated by means of the gel‐permeation chromatographic technique. The intensities of the UV absorption bands of the carbazolyl group diminished with increasing molecular weight of the polymer from 1200 to ca. 104, and were constant when the molecular weight was higher than 104. The diminution of the absorption intensities was regarded as a hypochromism, and the hypochromism was discussed with respect to the local structure of PNVC in solution.
Copolymerization of (−)‐ and (±)‐menthyl acrylates
Authors: Matsuzaki Kei , Hosonuma Kunihiko , Kanai Taiichi , Kobayashi Ken‐ichi 
Published: April 2003

AbstractCopolymerizations of (−)‐ and (±)‐menthyl acrylates were carried out and the optical rotation and the optical density ratio, D1372/D1235, which was an index of stereoregularity, were determined. The optical rotation of radically obtained poly[(−)‐menthyl acrylates] were higher and the optical density ratios were lower than those of anionically obtained polymers. The optical density ratios of the anionically obtained copolymers of (−)‐and (±)‐menthyl acrylates descreased with the decrease of (−)‐monomer content in the starting monomers, indicating the decrease in the isotacticity of the copolymers. Thus, the asymmetric effects of optically active menthyl groups on the main chain configurations in anionic polymerization were ascertained.
Die radikalische Polymerisation des 3,3,3‐Trichlorpropens in Substanz mit Dicyclohexylperoxydicarbonat
Authors: Szafko J. , Turska E. , Lopatina G. P. 
Published: April 2003

AbstractEs wird die Polymerisation des 3,3,3‐Trichlorpropens mit Dicyclohexylperoxydicarbonat als Initiator in Substanz untersucht. Im Temperaturbereich von 303–343 K gehorcht die Anfangsgeschwindigkeit der Polymerisation der Beziehung

Für die Temperaturabhängigkeit der Bruttogeschwindigkeitskonstante gilt:

Die Initiierungsgeschwindigkeiten wurden mit der Inhibitormethode unter Verwendung von Toluchinon (2‐Methyl‐1,4‐benzochinon) als Inhibitor bestimmt; der Radikalausbeutefaktor („efficiency”︁) beträgt 0,25±0,03. Zwischen den Geschwindigkeitskonstanten für Wachstum und Abbruch, kp und kt, besteht die Beziehung:
Zur stereospezifischen Polymerisation von Methylmethacrylat mit Grignard‐Reagens
Authors: Miyamoto Takeaki , Tomoshige Shozo , Inagaki Hiroshi 
Published: April 2003

AbstractGegenstand unserer Untersuchungen war die Konfiguration von Polymethylmethacrylat (PMMA), das aus Methylmethacrylat mit Butylmagnesiumchlorid in Toluol bei −50°C einmal in Abwesenheit (Blank‐Polymerisation) und einmal in Gegenwart von vorgelegtem isotaktischem PMMA (Replica‐Polymerisation) dargestellt wurde.Es zeigte sich, daß bei der Blank‐Polymerisation eine Beziehung besteht zwischen dem Monomer‐Umsatz und der Konfiguration der erhaltenen Polymerisate: die bei niedrigen Umsätzen (<10%) erhaltenen Polymerisate waren hauptsächlich isotaktisch und mit zunehmendem Umsatz nahm die Isotaktizität zunächst ab, und nahm dann einen konstanten Wert an. Ferner wurden die acetonunlöslichen Fraktionen der Produkte mittels einer konkurrierenden Adsorptionsmethode in präparativem Maßstab in ihre Komponenten aufgetrennt. Der Anteil isotaktischer Triaden in der isotaktischen Kompo+nte war bemerkenswert hoch (etwa 85%), während der Anteil syndiotaktischer Triaden in der syndiotaktischen Komponente etwa 60 bis 70% betrug. Das Molekulargewicht der syndiotaktischen Komponente war beträchtlich niedriger als dasjenige der isotakti+hen Komponente. Aus dem Verhalten der acetonlöslichen Fraktionen bei der Dünn+hicht‐Chromatographie ging hervor, daß sie ataktisch waren.Die Polymerisate, die bei der Replica‐Polymerisation erhalten wurden, sind in scharfem Gegensatz zu den durch Blank‐Polymerisation gewonnenen Produkten besonders dann +berwiegend syndiotaktisch, wenn das Mengenverhältnis von entstandenem zu zugegebe+em Polymeren niedriger als etwa zwei ist. Der Unterschied zwischen den beiden Polymerisationsgeschwindigkeiten liegt innerhalb der experimentellen Fehlergrenze.
The proton chemical shifts and the conformations of the unbranched paraffin hydrocarbon C44H90 in solution
Authors: Ando Isao , Nishioka Atsuo 
Published: April 2003

AbstractThe temperature dependence of the proton chemical‐shift difference between the methyl and methylene groups in the unbranched paraffin hydrocarbon C44H90 was calculated by using Pople's approximation and the Monte Carlo method, and the calculated results could interpret the experimental behavior in carbon tetrachloride solution. From these results, it was estimated that the energy difference between the trans and gauche states is 1880–2300 J/mol, and the four‐bond interaction energy is 5270–6275 J/mol. The estimated values agree with those obtained from comparison of the calculated and observed average‐dimension and its temperature coefficient by Abe et al. Further, the calculated chemical‐shift difference was associated with the unperturbed dimension and its temperature coefficient.
Vinyl polymerization by metal complexes, 21. Initiation mechanism of vinyl polymerization by amine‐copper(ii) complexes in the presence of carbon tetrachloride
Authors: Inaki Yoshiaki , Ishiyama Masanobu , Hibino Kunio , Takemoto Kiichi 
Published: April 2003

AbstractIn order to elucidate the initiation mechanism of the vinyl polymerization by amine‐copper(II) complexes in aqueous solution, in the presence of carbon tetrachloride, the reaction of amine‐copper(II) complexes with carbon tetrachloride was studied by ESR, visible spectroscopy, and the spin trapping method. The ESR signal of copper(II) disappeared during the reaction, suggesting the reduction of copper(II) to copper(I) in the initial step of the reaction. This reduction was also ascertained both by visible spectral changes and by the cuproin coloration method. The initiation mechanism is discussed based on these results and the information about the initiating free radical species by the spin trapping method.
Synthèse et caractérisation de copolymères séquencés poly(méthacrylate d'alkyle)/poly(oxyéthylène)
Authors: Seow Pin Kwong , Gallot Yves , Skoulios Antoine 
Published: April 2003

AbstractOn a synthétisé à l'aide de la technique de polymérisation par voie anionique des copolymères séquencés poly(méthacrylate d'alkyle)/poly(oxyéthylène). On a opéré sous vide, en milieu tétrahydrofuranne; l'initiateur utilisé était le diphénylméthylpotassium.Dans le cas des copolymères poly(méthacrylate d'éthyle)/poly(oxyéthylène), les échantillons ont été fractionnés par addition progressive de triméthyl‐2,2,4 pentane à leur solution dans le benzène. On a caractérisé les différentes fractions par résonance magnétique nucléaire diffusion de la lumière. On a montré que les copolymères bruts ainsi préparés ne renfermaient pas d'homopolymère et que les fractions recueillies présentaient une faible polydispersité en masse moléculaire et en composition.
Caesium as counter‐ion in the anionic polymerization of ethylene oxide, 3. Dimethyl sulfoxide as solvent
Authors: Nenna Sergio , Figueruelo Juan E. 
Published: April 2003

AbstractThe anionic polymerization of ethylene oxide in dimethyl sulfoxide using the caesium 3,6‐dioxa‐1‐octanolate as initiator was studied at 50°C. Conductivity measurements have shown that the living polymer exists as free ion or contact ion pair. The reaction rates were found to be first order with respect to monomer and 1,9 order with respect to initiator with a mean value for the propagation rate constant of 60 mol −1, 9l1, 9s−1. Based on the experimental findings a polymerization mechanism is proposed.
Contribution à l'étude de la sorption de dioxanne‐1,4 par un film amorphe de poly(téréphtalate d'éthylène glycol) et des modifications physiques du polymère engendrées par cette sorption, 1. Étude de la sorption du dioxanne‐1,4 dans le polymère amorphe
Authors: Moser Daniel , Gavet Louis , Chabert Bernard , Berticat Philippe , Vallet Georges 
Published: April 2003

AbstractLes méthodes radiochimiques utilisées permettent de suivre la pénétration du dioxanne‐1,4 dans un film de poly(téréphtalate d'éthylène glycol) (PETP) amorphe, par dosage du taux de reprise de ce solvant et par estimation de la profondeur de pénétration de ce dernier dans l'échantillon polymérique. Elles contribuent également à l'étude de la désorption du dioxanne‐1,4 retenu par le polymère dans différentes conditions de séchage, ou par échange avec un autre solvant dont la sorption permet de caractériser des modifications morphologiques survenues au cours du séchage du film prétraité au dioxanne‐1,4.La cinétique de sorption du dioxanne‐1,4 en milieu liquide étant excessivement rapide, une étude gravimétrique de sorption de vapeurs de dioxanne‐1,4 a montré le rǒle plastifiant de ce solvant ainsi que l'existence d'un phénomène de rejet de celui‐ci, par suite d'une cristallisation contrǒlée par la plastification du PETP. La sorption du dioxanne‐1,4 est fortement exothermique et des interactions polymère‐solvant peuvent se produire en entraǐnant la fixation de dioxanne‐1,4 dans le polymère.
Solubilisation de polystyrène dans la phase lamellaire d'un copolymère biséquencé polystyrène/polyisoprène
Authors: Ptaszynski Bogdan , Terrisse Jean , Skoulios Antoine 
Published: April 2003

AbstractOn a étudié par diffraction des rayons X aux petits angles de Bragg la solubilisation d'une série de polystyrènes de masse moléculaire variable dans la phase lamellaire d'un copolymère biséquencé polystyrène/polyisoprène.On a d'abord montré que la solubilisation correspond à un état d'équilibre véritable du système et non pas à un état métastable dǔ à l'insertion accidentelle de l'homopolymère dans l'édifice.On a corroboré ensuite les conclusions énoncées précédemment: l'homopolymère se solubilise tant que sa masse moléculaire ne dépasse pas une masse comparable à celle des séquences parentes; il se localise à l'intérieur des microdomaines de ségrégation qui contiennent les séquences de měme nature; il s'y distribue enfin de manière assez uniforme.On a observé, enfin, un phénomène de fractionnement, lié sans doute à la polydispersité non négligeable des échantillons.
Dehydrochlorination of poly(sulfonyl‐co‐2‐chloroethylene)
Authors: Cais Rudolph E. , O'Donnell James H. 
Published: April 2003

AbstractPoly(sulfonyl‐co‐2‐chloroethylene)s were shown to have an enhanced tendency to undergo dehydrochlorination compared with poly(vinyl chloride). Dehydrochlorination was observed under the following conditions: (a) during preparation of the copolymers by γ‐radiation initiated copolymerization of vinyl chloride and sulfur dioxide, (b) by γ‐irradiation of the polymer, (c) during ageing, (d) on heating and (e) in solution in basic solvents, such as DMSO. The dehydrochlorination was studied by microanalysis, by IR and UV spectroscopy and by 1H and 13C NMR. Hydrogen chloride was eliminated preferentially from chloroethylene units occurring between two sulfonyl units. The proportion chloroethylene units: sulfonyl units in poly(sulfonyl‐2‐chloroethylene) decreased from ≈ 2:1 at a copolymerization temperature of 0°C to ≈ 1:1 at a temperature of −78°C. The results show, that dehydrochlorination of copolymers prepared at low temperatures is a serious problem, especially with initiation by γ‐irradiation.
Über Polyamide mit 2,4‐Imidazoldiyl‐Bausteinen
Authors: Manecke Georg , Carl Brigitte 
Published: April 2003

Abstract2,4‐Bis(aminophenyl)imidazole 1a, 2a und 3 werden mit aromatischen und aliphatischen Dicarbonsäure‐dichloriden zu linearen, thermostabilen Polyamiden mit 2,4‐Imidazoldiyl‐Bausteinen umgesetzt. Durch Verwendung von Imidazolderivaten mit methyliertem bzw. unsubstituiertem Stickstoff im Imidazolring wird gezeigt, in welchem Maße die Thermostabilität der resultierenden Polyamide erhöht wird, wenn die Möglichkeit zur Ausbildung von NHN‐Wasserstoffbrücken zwischen den Ketten vorhanden ist. Die Polyamide 10c, 11c, 12c, die mit 4,4′‐Oxydiphenylen‐dicarbonsäuredichlorid (9c) bereitet werden, zeigen ausgezeichnete Thermostabilität, faserige Beschaffenheit und hohe Werte für die inhärente Viskosität.
Darstellung und eigenschaften der koordinationsverbindungen von poly(vinylpyridin)en mit den chloriden von Ru, Rh und Pd
Authors: Roda Jan , Hrabák František 
Published: April 2003

AbstractEs wurden die unlöslichen Koordinationsverbindungen von Ru, Rh und Pd mit den amorphen Polymeren des 2‐, 3‐ und 4‐Vinylpyridins sowie mit dem isotaktischen und dem syndiotaktischen Polymeren des 2‐Vinylpyridins dargestellt. Das Molverhältnis zwischen dem Metallchlorid und der Monomereinheit des Vinylpyridins in den Ausgangsgemischen wurde mit dem in den resultierenden Koordinationsverbindungen verglichen und die chemische Zusammensetzung der letzteren bestimmt. Anhand der gefundenen Daten wird der wahrscheinliche Charakter der isolierten Koordinationsverbindungen der Poly(vinylpyridin)e diskutiert.
The thiol/dimethyl sulfoxide system as initiator of polymerization in benzene medium, 2. Kinetic studies
Authors: Roy Kamal Kumar , Palit Santi Ranjan , Pramanick Dinabandhu 
Published: April 2003

AbstractThe kinetics of butanethiol/dimethylsulfoxide (DMSO) initiated polymerization of methyl methacrylate in benzene medium was studied gravimetrically. The thiol acts as the reducing component of the initiator system and also as a transfer agent. The order with respect to [Butanethiol] is 0,48. In the lower concentration region between 4,69.10−4 and 9,38.10−2mol 1−1, DMSO behaves simply as the oxidant of the initiator system, and the rate of polymerization has the usual square root dependence on [DMSO]. But above the concentration of 9,38.10−2mol 1−1 and up to 1,40mol 1−1, DMSO acts both as an oxidizing agent and as a retarder, forming an adduct with the growing radicals, which propagates the reaction with a retarded rate. The order with respect to monomer concentration is 1,04, when DMSO is used in the lower concentration range and it increases to 1,25 when [DMSO] is higher than 9,38.10−2mol 1−1. Thiols of different structures affect the rate significantly. The rate of polymerization is also dependent on the polarity and viscosity of the solvent being a maximum in benzene and a minimum in ethyl acetate. The efficiency of initiation of the initiator system is 60–80% and the overall activation energy is 72,45 kJ mol−1. An appropriate kinetic expression was derived to explain the results.
Cristallisation du poly(oxyéthylène) dans des copolymères séquencés, 2. Étude de la structure et de la texture
Authors: Seow Pin Kwong , Gallot Yves , Skoulios Antoine 
Published: April 2003

AbstractA l'aide de la diffraction des rayons X aux petits angles, on a étudié la structure lamellaire d'une série de copolymères biséquencés poly(oxyéthylène)/poly(méthacrylate d'éthyle) et poly(oxyéthylène)/polystyrène, soit en fonction de la température de cristallisation, soit en fonction de la température de recuit.L'épaisseur des lamelles croît avec la température, l'indice de repliement des chaînes cristallisées variant apparemment de façon continue. L'augmentation brusque de l'épaisseur observée à 40°C pour les expériences de recuit a été interprété en termes de débloquage des séquences amorphes au‐dessus de la température de transition vitreuse.Par microscopie optique en lumière polarisée, on a examiné la texture sphérolithique des échantillons.
Synthesis of (styrene‐p‐chlorostyrene) tri‐block copolymers and their properties in dilute solutions
Authors: Shima Mikiko , Ogawa Etsuyo , Konishi Kazue 
Published: April 2003

AbstractTwo series of well‐characterized (styrene‐p‐chlorostyrene) tri‐block copolymers of BmAnBm‐ and AmBnAm‐types (A: styrene monomeric unit, B: p‐chlorostyrene monomeric unit. n = 2m denotes the number of units) were synthesized by anionic polymerization technique. Their intrinsic viscosities in toluene, 2‐butanone, and cumene were studied over a wide range of molecular weights. The data were analyzed on the basis of two‐parameter theories. The unperturbed dimensions of the block copolymers are expressed by those of the parent homopolymers and the composition. The conformational behaviours of the BmAnBm and AmBnAm copolymers are similar in the non‐selective solvents, toluene and 2‐butanone, whereas in the selective solvent, cumene, which is a Θ solvent for poly‐p‐chlorostyrene and a good solvent for polystyrene, a molecule of the AmBnAm copolymers takes a more extended chain conformation and a greater value of the longrange interaction parameter than the BmAnBm copolymers of the same composition. However, an anomaly which suggests “Intrachain phase separation” was not observed in the viscosity behaviours of the block copolymers in cumene as well as in toluene and 2‐butanone.
Structure lamellaire des copolymères séquencés: Paramètres structuraux et coefficient de partage du solvant dans le gonflement du copolymère biséquencé polystyrène/polyisoprène
Authors: Ionescu Maria‐Livia , Skoulios Antoine 
Published: April 2003

AbstractOn a étudié en présence de divers solvants et par diffraction des rayons X aux petits angles la structure lamellaire d'un copolymére biséquencé polystyrène/polyisoprène.Grâce à l'analyse de l'intensité des raies de diffraction, on a mesuré le coefficient de partage des solvants entre les microdomaines de ségrégation.On a examiné l'évolution des paramètres structuraux en fonction de l'affinité de chaque solvant à l'égard de l'une ou l'autre des séquences. On a montré que le gonflement de l'édifice lamellaire s'effectue essentiellement dans le sens de l'épaisseur des lamelles lorsque le solvant est nettement préférentiel de l'une des séquences, alors qu'il s'effectue parallèlement aux interfaces lorsque le solvant se localise également dans tous les microdomaines.
Free radical copolymerization of butadiene and vinylferrocene
Authors: George Maurice H. , Hayes Gerard F. 
Published: April 2003

AbstractThe free radical copolymerization of butadiene and vinylferrocene was studied at 60°C in 1,4‐dioxane. Copolymerization occurs readily to give low molecular weight random copolymers. The reactivity ratios are r1 (butadiene) = 3,5±0,5 and r2 (vinylferrocene) = 0,30±0,10 and the Q and e values for vinylferrocene are 0,68 and −1,05, respectively. The copolymers are shown to contain a paramagnetic species which is identified as a high spin Fe(III) complex.
Infrared spectroscopic studies on polyethylene, 3. The bromination of unsaturated groups
Authors: McRae Margaret A. , Maddams William F. 
Published: April 2003

AbstractResults for the rates of bromination of vinyl, vinylidene, and trans vinylene groups in various types of polyethylene are reported and interpreted. It is shown that for two Phillips type vinyl‐containing polymers, one near‐linear and the other ethyl branched, the uptake of vapour phase bromine at ambient temperature is rapid, because the unsaturation lies largely in amorphous regions. Plots of log (At/A0) against time, where A0 and At are the absorbances at 910 cm−1 initially and after time t, are linear until bromination is almost complete, indicating that it is a diffusion controlled process. The subsequent slower bromination is tentatively interpreted in terms of vinyl groups sited in defective surface layers of the crystalline lamellae. Both types of bromination occur more readily with the ethyl branched polymer than with the linear material. Bromination of the residual unsaturation in wholly crystalline regions occurs only in the molten state. X‐ray diffraction measurements confirm that the majority of the vinyl groups are sited in amorphous regions.Similar conclusions are drawn for vinylidene and trans vinylene groups, but the rate of bromination of polymers containing the latter type of unsaturation does not wholly correlate with the amorphous content. From this evidence and from measurements on a thicker film of the ethyl branched vinyl polymer it is concluded tentatively that there are differences in the amorphous regions which lead to varying rates of diffusion of bromine vapour.
Melting and degradation behaviour of needle‐like poly(oxymethylene) crystals
Authors: Iguchi Masatoshi 
Published: April 2003

AbstractDSC/TG (differential scanning calorimetry/thermal gravimetry) simultaneous measurements have been carried out for needle‐like and other poly(oxymethylene) crystals and the occurrence of degradation, overlapping the melting, has been confirmed for needle‐like and fibrous extended‐chain crystals. A theory to analyze the DSC curves with reference to the corresponding TG has been formulated and the contributions from the melt and the degradation have been resolved by means of computer curve‐fitting. For needle‐like crystals, the heat of fusion, 2260 cal/mol (9450 J/mol) and the melting point, 183–184°C (as well as the heat of degradation, 13,17 kcal/mol [55,05kJ/mol]) have been obtained and discussed with reference to the data from other samples. Systematic experiments for the effect of running conditions on the shape of DSC curves have been made and described in the Appendix.
Synthèse d'acides à structures terpéniques par oligomérisation anionique
Authors: Bormann Sylvie , Brossas Jean , Clouet Françoise 
Published: April 2003

AbstractNous décrivons la synthèse de diacides à structures terpéniques par la méthode de dimérisation anionique que nous avons déjà utilisée lors de la préparation d'hydrocarbures et d'alcools ter péniques. L'étude des différents isomères obtenus a été réalisée par chromatographie en phase gazeuse et par spectroscopie NMR. Nous avons observé que pour obtenir de bons rendements la dimérisation doit être réalisée à température ambiante et suivie d'une désactivation de la solution “vivante” sur de la carboglace. De l'analyse structurale des isomères, il ressort que deux formes limites mésomères A et B ont un poids prépondérant dans la représentation de l'anion‐radical isoprène en phase homogène. Les acides isomères majoritaires sont ceux qui possèdent un enchaînement terpénique 1–4, 4–1.