bluuebunny/crossref_metadata_2025_split huggingface dataset:
The polymerization mechanism of methyl methacrylate initiated with ceric ion
Authors: Narita Hiroshi , Okamoto Susumu , Machida Seishi 
Published: April 2003

AbstractThe polymerization of methyl methacrylate in the presence of ceric ion and pinacol in acetic acid solution has been investigated. Acetone formed in the reaction products has been determined and the mechanism and kinetics of the polymerization have been studied. It has been confirmed that the primary radical formed from pinacol reacts with not only the monomer to produce a monomer radical and initiate the polymerization but also with ceric ion. Under the present experimental conditions, the reaction of the primary radical with ceric ion is about 127 times as fast as that with monomer. The monomer radical produced reacts with another monomer to propagate polymerization. The polymerization is terminated by reaction of the polymer radical with ceric ion. The rate of polymerization was proportional to [pinacol], [monomer]2 and reciprocal to [CeIV].
Studies in polymerisation of vinyl acetate. I.
Authors: Potnis S. P. , Deshpande A. M. 
Published: April 2003

AbstractPolymerisation of vinyl acetate has been studied in bulk and solution at 60°C using benzoyl peroxide as initiator. From the results obtained, it has been shown that, the rate of polymerisation is proportional to the square root of initiator concentration in both the cases. The values of the transfer constants due to the monomer and initiator, (CM), (CI), the overall rate constant (K), the quotient of the rate constant of propagation and the square root of the rate constant of termination (KP/Kt1/2) and the rate constant for the initiation (Ki) have been determined for bulk polymerisation. Utilising some of the constants obtained in bulk polymerisation and studying the polymerisation of vinyl acetate in glacial acetic acid in detail, values of CI, K, (Kp/Kt1/2), Ki at different ratios of solvent (S) and monomer (M) concentration ([S]/[M]) as also chain transfer constant (Cs) for glacial acetic acid have been calculated.
Copolymerization of α‐hydroxyisobutyric acid anhydrosulfite with vinyl compounds1
Authors: Inoue Shohei , Tsubaki Kazumi , Yamada Takeyoshi , Tsuruta Teiji 
Published: April 2003

AbstractPolymerization of α‐hydroxyisobutyric acid anhydrosulfite was carried out in some vinyl compounds in the presence of azo‐bis‐isobutyronitrile at 80°C. In acrylonitrile, a graft copolymer consisting of polyacrylonitrile and polyester[OC(CH3)2CO]x̄chains was obtained. Free radical nature of the grafting reaction is suggested. In methacrylonitrile a polymeric product was formed with polymethacrylonitrile main chains in which the cyano groups partly reacted with one molecule of the anhydrosulfite, introducing the units of [OC(CH3)2CO] into the polymer.
Cyclopolycondensations. XI. Syntheses of alicyclic polybenzoxazinones
Authors: Hagiwara Yoshichi , Ikeda Kojuro , Kurihara Masaru , Yoda Naoya 
Published: April 2003

AbstractAlicyclic polyamic acids and their polybenzoxazinones were prepared by the polycondensation of trans‐ and cis‐1.4‐ and 1.3‐cyclohexane dicarboxylic acid chloride with 4,4′‐diaminobiphenyl‐3.3′‐dicarboxylic acid. Comparing these alicyclic polymers with corresponding fully aromatic polybenzoxazinones, it was demonstrated that the symmetry of the molecules rather than aromaticity is a more important factor for the solubility of polymers. The trans‐1.4‐acid chloride is easier polymerizable than the cis‐1.4‐isomer. The polybenzoxazinone from the trans‐1.4‐isomer shows higher thermal stability than that from the cis‐1.4‐isomer. The reaction variables of the cyclopolycondensation were studied and some of the properties of the resulting polymers are described.
Cationic polymerization of α·β‐disubstituted olefins. Part X. Effect of polymerization conditions on the steric structure of poly(methyl propenyl ether)
Authors: Higashimura Toshinobu , Ohsumi Yukihiko , Okamura Seizo , Chûjô Riichiro , Kuroda Takamune 
Published: April 2003

AbstractThe effect of polymerization conditions on the steric structure of the polymer was studied for the polymerization of methyl propenyl ether (MPE) catalyzed by BF3·O(C2H5)2. The steric structure of the α‐ and β‐carbon atoms of the polymers were measured by NMR spectroscopy. The threo‐meso configuration of the α‐ and β‐carbons of the polymer obtained from mixtures of cis‐ and trans‐MPE increased with increasing amount of trans‐isomer in the monomer mixture. We conclude that the pure trans‐isomer would give a threo‐di‐isotactic polymer. As the polarity of the solvent increased, the proportion of threo‐meso structure decreased in the polymer obtained from trans‐rich monomer, but it increased in the polymer obtained from cis‐rich monomer. The effect of the solvent on the steric structure of the polymer obtained from the cis‐isomer was greater than on that of the polymer from trans‐isomer. An interaction between the β‐methyl group of the attacking monomer and that of the penultimate unit was recognized on the basis of the change in the steric structure of the polymer with polymerization temperature. The α‐carbons of the polymer obtained were found to have the racemic configuration whilst the β‐carbons are hardly ever racemic. The mechanism of the propagation reaction is discussed on the basis of these results.
Die chemische Heterogenität von Copolymerisaten. 5. Sequenzlängenverteilung
Authors: Markert Von Gerhard 
Published: April 2003

AbstractDie bekannten Gleichungen zur Berechnung von Sequenzlängen gelten für chemisch einheitliche Copolymerisate. Es wird eine Methode beschrieben, wie man die Sequenzlängenwahrscheinlichkeiten für chemisch heterogene Copolymerisate ermitteln kann, wenn die Häufigkeitsverteilung der chemischen Zusammensetzung bekannt ist. Das Verfahren wird am Beispiel des Monomerenpaares Methylmethacrylat/Äthylacrylat demonstriert und diskutiert.
Mechanochemische Synthesen durch Polykondensation mit Polyestern als Grundsubstanz. 1. Mechanochemische Polykondensation von polyäthylenterephthalat mit Äthylendiamin
Authors: Oprea Von Cleopatra Vasiliu , Neguleanu Claudia , Simionescu Cristofor 
Published: April 2003

AbstractEs wird erstmals untersucht und bestätigt, daß die Auslösung von Polykondensationsvorgängen auf mechanochemische Weise möglich ist, wobei als polymerer Träger das Polyäthylenterephthalat und als Kondensationspartner Diamine (Äthylen‐ und Hexamethylendiamin) sowie zweibasische Säuren (Adipinsäure) verwendet werden. Der Einfluß der Dauer der mechanischen Beanspruchung und des Mischungsverhältnisses der Reaktionspartner auf den Umsatz wird diskutiert. Die Kondensationsprodukte werden durch chemische und spektroskopische Methoden sowie durch Bestimmung von Löslichkeit und Schmelzpunkt gekennzeichnet.Die Existenz mechanochemischer Umsetzungen wird auch an anderen Systemen (Polyamiden/zweiwertigen Alkoholen) nachgewiesen.
Über das 3.4‐diamino‐styrol. I
Authors: Manecke Von G. , Rotter U. 
Published: April 2003

AbstractBei der Darstellung von 3.4‐Diamino‐styrol aus 1‐[3′.4′‐Diamino‐phenyl]‐äthanol sowie aus 3.4‐Diamino‐zimtsäure entsteht 3.4‐Diamino‐äthyl‐benzol als Nebenprodukt. 3.4‐Diamino‐styrol wird ohne Nebenprodukt durch Reduktion von 3‐Nitro‐4‐amino‐styrol erhalten; es läßt sich zu entsprechenden Vinylheterocyclen kondensieren.
Kinetic studies on the polymerization of 1.3‐dioxepane: Initiated with triethyl oxonium tetrafluoroborate
Authors: Okada Masahiko , Kozawa Shigeyuki , Yamashita Yuya 
Published: April 2003

AbstractThe kinetics of the polymerization of 1.3‐dioxepane by triethyl oxonium tetrafluoroborate has been studied in methylene chloride. The polymerization was preceded by a long induction period characteristic of the polymerization of cyclic formals by this initiator. The degree of polymerization of the polymer was rather high from the outset of the polymerization, increased linearly with increasing conversion up to about 50% and then leveled off. The formation of a polymer in an equimolar reaction of the monomer and the initiator can be explained by initiation being rather slow compared with propagation. It was found that addition of a small amount of isobutyl vinyl ether accelerated the rate of polymerization and shortened the induction period markedly.
The structural effects of annealing time and temperature on the paracrystal‐crystal transition in isotactic polypropylene
Authors: Zannetti Roberto , Celotti Giancarlo , Fichera Annamaria , Francesconi Romolo 
Published: April 2003

AbstractThe influence of different annealing treatments on the crystalline order of isotactic paracrystalline polypropylene is described.The result support an intramolecular transformation mechanism based on a rewinding of hellcal segments of different lengths having opposite senses of spiralization. Such a mechanism is in agreement with the annealing time dependence of a particular order parameter and is sensitive to the temperature and not to the annealing time once the saturation order value is reached. This saturation phenomenon occurs very quickly at the higher temperatures.
Poly(2‐[α‐3H]vinylpyridine 1‐oxide)
Authors: Gregson Leslie , Holt Paul 
Published: April 2003

AbstractPoly(2‐vinylpyridine 1‐oxide), when injected into animals, counteracts the pathogenic effects of inhaled silica dust. To study its distribution in the cells, a specifically labelled polymer has been synthesised by reducing 2‐acetylpyridine with tritium, dehydrating, polymerising then oxidizing the polyvinyl product. Some of the tritium (17%) enters the aromatic ring by exchange and there is a small loss of tritium by exchange with solvents. At the stage of reduction, there is preference for CT bond formation rather then CH.
Theoretical relationships between parameters in the KUHN‐MARK‐HOUWINK‐SAKURADA equation
Authors: Kamide Kenji , Kataoka Akira 
Published: April 2003

AbstractSome general theoretical relationships between Km and a in the KUHN‐MARK‐HOUWINK‐SAKURADA equation:

have been derived on the basis of the treatments of UEDA‐KAJITANI (UK) and SHIOKAWA‐OYAMA (SO) which relate viscosity expansion factor αη to excluded volume effect z, combining with the FLORY‐FOX (FF) intrinsic viscosity equation.The combination of the treatments of FLORY‐FOX and UEDA‐KAJITANI (FF‐UK) led to

and of the FLORY‐FOX and SHIOKAWA‐OYAMA (FF‐SO) to

In these equations K is FLORY's K value and M0 is a molecular weight representative of the molecular weight range covered by the intrinsic viscosity/molecular weight study.It has appeared that the upper limit of a applicable in the treatments including the FF‐UK and FF‐SO thus obtained follows the order:

where Fi is FIXMAN, KSR, KURATA‐STOCKMAYER‐ROIG, KY, KURATA‐YAMAKAWA.The Km‐a relations predicted by the theoretical treatments mentioned above has been examined by the experimental data on atactic polypropylene, polyhexene‐1 sulphone, polyvinyl acetate, polymethyl methacrylate, polystyrene, and polyacrylonitrile.
Polymer synthesis by 1.3‐cycloaddition reaction. II
Authors: Gilliams Y. , Smets G. 
Published: April 2003

AbstractAliphatic bisazides, 1.5‐bis‐azidopentane, 1.4‐bis‐azidobutane and bis‐(β‐azidoethyl)‐ether have been condensed with hexamethylene, m‐ and p‐phenylene bismaleimides and give poly‐Δ2‐1.2.3‐triazolines. Similarly 1.4‐ and 1.5‐bisazidoalkanes were condensed with m‐ and p‐diethinylbenzene, and afford the corresponding triazole polymers. With 1.6‐bis‐diazohexane, the diethinylbenzene give pyrazolenine or pyrazole polymers depending on the reaction conditions.The structures of these new polymers were demonstrated on the basis of their infrared and NMR spectra, and comparison with those of their low molecular weight model substances.
Polymerization of styrene initiated by trichloroacetyl chloride and water
Authors: Sakota Naokazu , Nakamura Hiroshi , Nishihara Koji 
Published: April 2003

AbstractThe polymerization of styrene initiated by trichloroacetyl chloride (TAC) and water was investigated. The reaction proceeded by an ionic mechanism and polymers of relatively low molecular weight were formed. From the analytical results of the polymer, it was suggested that the ionic decomposition of an intermediate complex formed by TAC and water yielded chloroformic acid which induced cationic polymerization of styrene.
Polymers containing intra‐molecular crosslinks
Authors: Longi P. , Greco F. , Rossi U. 
Published: April 2003

AbstractPrevious research on polymer intra‐molecular crosslinks has been pursued in order to obtain copolymers containing very stable intra‐molecular crosslinks in amounts of 1.5–3 mole‐%.From viscometric and osmotic molecular weight determinations of the obtained copolymers, it can be inferred, as theoretically expected, that formation of intra‐molecular crosslinks remarkably reduces the size of random coiled macromolecules in diluted solutions, regardless of chemical structure of such crosslinks and such macromolecules.
The determination of the distribution of molecular weight of polymer samples
Authors: Carraher Charles E. , Brandt Thomas W. 
Published: April 2003

AbstractA new method is presented for the determination of the molecular weight distribution from intrinsic viscosity and weight fraction data obtained for a series of fractions. A GAUSSian distribution of molecular weights for the individual fractions is assumed. The experimental intrinsic viscosity of the individual fractions is identified with the maxima of the differential mass distribution of the individual fraction. The weight fraction as a function of molecular weight for the individual fractions are summed to give a molecular weight distribution curve characteristic of the unfractionated sample. Theoretical relationships for the approach are presented. The corresponding computer program is given in Fortran IV. The method is tested using literature data and original measurements on a polyurea.
Gelchromatographie. 9. Mitt.: Polymethacrylatgele1
Authors: Heitz Von Walter , Winau Herbert 
Published: April 2003

AbstractDer Einfluß der Herstellungsbedingungen auf die gelchromatographischen Eigenschaften von Polymethylmethacrylatgelen, die mit Glykoldimethacrylat vernetzt sind, wurde untersucht.Homogen‐vernetzende Copolymerisation führt zu Gelen mit Ausschlußmolekulargewichten bis ca. 6000. Durch Copolymerisation in Gegenwart von Inertkomponenten entstehen heterogene Strukturen. Durch heterogen‐vernetzende Copolymerisation können Gele mit Ausschlußmolekulargewichten, die formal 1010 und mehr entsprechen, erhalten werden.Die Änderung der Vernetzerkonzentration und des Solvatationsvermögens der Inertkomponente erlaubt es, die Ausschlußmolekulargewichte der Gele in weiten Grenzen zu variieren.Die Polymerisation der Dimethacrylate von Polyäthylenoxiden führt zu hydrophilen Gelen, die keine Hydroxylgruppen enthalten. Sie sind zu Trennungen in Wasser und in organischen Lösungsmitteln geeignet.
Oligomere als modelle für poly‐p‐xylyliden. Untersuchungen über stilbene. XLIX.1
Authors: Drefahl Von Günther , Kühmstedt Rolf , Oswald Hermann , Hörhold Hans‐Heinrich 
Published: April 2003

AbstractDie folgenden durch π‐Elektronen bedingten Eigenschaften einer Reihe von wohldefinierten Oligoxylylidenen mit trans‐Doppelbindungen der allgemeinen Struktur I
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werden untersucht: UV‐Spektren in Lösung, UV‐Spektren der Festkörper (Reflexionsspektren), Festkörperfluoreszenzspektren und die spektrale Abhängigkeit der Photoleitfähigkeit. Mit einem quantenmechanischen Näherungsverfahren werden die π–π*‐Anregungsenergien für die Glieder der Reihe berechnet. Es wird gefunden, daß die betrachteten elektronischen Eigenschaften sehr schnell gegen einen Grenzwert konvergieren, der praktisch schon mit n = 3 erreicht wird. Hieraus ist die Extrapolation auf entsprechende Eigenschaften des Polyxylylidens möglich.
Viscosity of polyelectrolyte solutions
Authors: Vink Hans 
Published: April 2003

AbstractThe viscosity behaviour of polyelectrolytes in solutions of low ionic strength has been investigated. The dependence of the viscosity on the degree of substitution, the molecular weight and the velocity gradient was studied in detail. The measurements were carried out in solutions of different ionic strength and the limiting intrinsic viscosity at zero ionic strength was determined by extrapolation. It was found that at zero ionic strength the exponent in the KUHN‐MARK‐HOUWINK equation has the value a = 1.1. It was further found that the intrinsic viscosities in the low and medium molecular weight region were considerably higher than those expected for rigid rodlike molecules of comparable size. The exceptionally high values of the intrinsic viscosity in solutions of low ionic strength indicate the presence of a pronounced “electroviscous effect” in these solutions.
Application of proton magnetic resonance spectroscopy to phenol novolak: Chemical shift in pyridine of methylene protons of phenol novolaks
Authors: Yoshikawa Toshio , Kumanotani Ju 
Published: April 2003

AbstractThe NMR spectroscopy of cresols, benzylphenols, and di‐, tri‐, and tetra‐nuclear phenolformaldehyde condensates using pyridine as solvent proved that their methyl or methylene groups which have ortho‐phenolic hydroxyl groups show their signals at much lower τ‐values as compared with those compounds having no ortho‐phenolic hydroxyl groups. Thus, the signals of ortho‐ortho, ortho‐para, and para‐para methylene types in novolak compounds could be separately observed in pyridine solution. Due to this specific properties of pyridine as NMR solvent, various phenol novolak resins could be characterized according to their modes of methylene links.
Fold structure of solution grown crystals of alkyl‐branched copolymers of polyethylene
Authors: Kawai Tōru , Ujihara Közaburo , Maeda H. 
Published: April 2003

AbstractAccording to the hypothesis that uncrystallizable units are excluded from the crystalline lattice into the surface of the crystals and concentrated in the folds, morphologies and textures of solution grown crystals of branched polyethylenes have been studied as functions of content and length of the branches by means of various techniques.Methyl, ethyl, and propyl branches were introduced into polyethylene chains by polymerization of mixtures of diazomethane and the corresponding higher diazoalkane. The crystals of these branched polymers grown from dilute solutions were treated with a selective oxidizing agent, fuming nitric acid. The degraded products were examined as regards the changes during the oxidation in molecular weight, weight‐loss, layer thickness (by low angle X‐ray studies), branch content (by IR analysis), unit cell dimensions, density and X‐ray crystallinities and morphology (by electron microscopy), with the aim of clarifying the nature of disordered material in polymer single crystals. It emerges that the thickness of the surface layer increases with the content and length of the branches and that the folds may be considered as irregular loose loops for crystals of polymers with a branch content beyond ca. one per 100 carbon atoms. The results also revealed less perfect order of the crystal lattice for polymers with higher degree of branching. Thus, the branches seemed to be concentrated in the loose loops in the surface layer and within the crystal defects, both of which are accessible to oxidation. The concentration of the branches within the folds was discussed in terms of the content and the length of the branches. It was also found that the thicker the surface layer, the poorer the morphology of the crystals.
Thermal degradation of poly‐4‐methylpentene‐1. Part 1. The products of degradation
Authors: Reginato Luigi 
Published: April 2003

AbstractPoly‐4‐methylpentene‐1 was degraded in the temperature range 291–341°C. The decomposition products were determined and their rate of evolution followed. Their formation is explained on the basis of a free radical chain mechanism in which hydrogen transfer plays an important role. A free radical abstracts a hydrogen on a tertiary carbon atom by a “back‐biting” mechanism, although there is also evidence of the abstraction of secondary hydrogen atoms. A split in the chain follows and a volatile fragment is formed. Isobutene and propane are the main components of the fraction volatile at room temperature, which accounts for about 9% of the total loss of weight. The rest consists of higher molecular weight branched hydrocarbons and olefins. The energy of activation for the loss of weight was found to be 53.5 kcal/mole.
ÜBer die aktivität von katalysatorgemischen aus metallorganischen verbindungen und TiCl4 bei der trioxanpolymerisation
Authors: Kabaivanov Von V. , Glavcev I. , Natov M. 
Published: April 2003

AbstractDie Geschwindigkeit der Trioxanpolymerisation, die Ausbeute an Polyoxymethylen und das Molekulargewicht des Polymeren wurden als Funktion des Ionencharakters der MeC‐Bindung in einer Reihe von Katalysatorsystemen aus TiCl4 und (C2H5)4Pb, (C2H5)4Sn, (C2H5)3Al, C2H5MgBr und n‐C4H9Li untersucht. Es ergab sich, daß die Aktivität der Katalysatorsysteme vom Ionencharakter der MeC‐Bindung abhängt. Die größte Aktivität bei TiCl4 als Cokatalysator weisen die metallorganischen Verbindungen mit 15–20% Ionencharakter auf.
Thermal properties of an ethylene/1‐butene block copolymer
Authors: Glegg G. A. , Gee D. R. , Melia T. P. 
Published: April 2003

AbstractA precision, adiabatic vacuum calorimeter and a differential scanning calorimeter have been used to measure the heat capacity of an ethylene/1‐butene block copolymer over the temperature range 80–450°K. An estimate has been made of heat capacity values below 80°K. Values of the heat capacity, entropy, enthalpy, and free energy are listed at 10°K intervals. A glass transition (200°K), a transition of unknown origin (335°K) and a melting transition (400°K) were observed.
Free rotation dimensions of linear polymers and application to polyalkylene oxides and polyalkylene sulphides
Authors: Huglin M. B. , Stepto R. F. T. 
Published: April 2003

AbstractA general expression has been derived for the mean square end‐to‐end distance 〈r2〉0f of linear polymers in the unperturbed freely rotating state. For a chain having q bonds per segment, a degree of polymerisation p and a total of N (= pq) bonds in the chain, the expression may be written 〈r2〉0f = N[A0/q + AB/pq]. Here A0 is the sum of scalar products of the bond vectors within a segment and A is the corresponding sum for pairs of bond vectors in adjacent segments. B denotes a series having a value dependent on p and the bond angles. The formula has been applied to the particular cases of [(CH2)m−X−]p where X = oxygen, X = sulphur and m = 1, 2, 3, 4, 6, and 10. Calculations of [〈r2〉0f/N]1/2 have been made for values of p in the range 1 ⩽ p ⩽ ∞, and the variation of [〈r2〉0f/N]1/2 with both chain length and chain structure discussed.
Ein beitrag zur kenntnis der N‐vinylimide
Authors: Hopff Von Heinrich , Becker Gert 
Published: April 2003

AbstractDie Darstellung von N‐Vinylsuccinimid, N‐Vinylphthalimid und 4‐Trimethylsilyl‐N‐vinylphthalimid durch Umvinylierung der Imide, durch alkalische Bromwasserstoffabspaltung aus N‐2‐Bromäthylimiden sowie durch katalytische Dehydratation von N‐2‐Hydroxyäthylimiden wurde untersucht; dabei wurden durchlaufene Zwischenstufen aufgeklärt.Die Copolymerisationsparameter der folgenden Monomerenpaare wurden bestimmt und die Q‐ und e‐Werte berechnet: N‐Vinylsuccinimid/N‐Vinylcarbazol, N‐Vinylsuccinimid/Maleinsäureanhydrid, N‐Vinylsuccinimid/Maleinsäuredimethylester, N‐Vinylphthalimid/Maleinsäureanhydrid, 4‐Trimethylsilyl‐N‐vinylphthalimid/Styrol.