bluuebunny/crossref_metadata_2025_split huggingface dataset:
Copolymerisation von Acrylnitril und α‐Chloracrylsäuremethylester
Authors: Dankovics Von A. 
Published: April 2003

AbstractDie Copolymerisation von Acrylnitril und α‐Chloracrylsäuremethylester in Emulsion wurde kinetisch untersucht. Umsatz, Grenzviskosität, spezifisches Gewicht, Zusammensetzung der Copolymeren und Induktionsperiode wurden bestimmt.Die Wahrscheinlichkeit für die Verteilung von Acrylnitril‐ und α‐Chloracrylsäremethylester‐Kettensegmenten wurde in Abhängigkeit von der Zusammensetzung des Monomeren gemisches bestimmt. Es wurde gezeigt, daß die aus den beiden Monomeren aufgebauten Makromoleküle aus unregelmäßig angeordneten, kurzen Sequenzen bestehen.Ferner wurde gezeigt, daß der Umsatz der Quadratwurzel der α‐Chloracrylsäuremethylester‐Konzentration direkt proportional ist. Die Induktionsperiode nimmt mit der Erhöhung der α‐Chloracrylsäuremethylester‐Konzentration ab.Der Umsatz hängt vom pH‐Wert des Reaktionsmediums ab. Bei pH > 7 ist die Reaktionsgeschwindigkeit sehr niedrig.
Umlagerungen bei der durch Lithiumbutyl initiierten Polyreaktion der Diene Isopren und Butadien
Authors: Gebert Wolfgang , Hinz Jürgen , Sinn Hansjörg 
Published: April 2003

AbstractBei der Reaktion von Lithiumbutyl mit Isopren in Diäthyläther entstehen Lithiumnonenyle, die bei der Zersetzung mit Wasser 36% 2‐Methylocten‐(1) und die cis‐trans‐Isomeren des 3‐Methyl‐octens‐(2) im Verhältnis 63:1 ergeben.Nach Entfernung des Diäthyläthers vom Lithiumnonenyl durch Abkondensation nach wiederholterZugabe von n‐Heptan werden die Kohlenwasserstoffe im Verhältnis 26 : 74 gefunden, während nach erneuter Zugabe von Diäthyläther wieder das Verhältnis 36 : 64 auftritt.Das Verhältnis der verschiedenen isomeren Lithiumnonenyle ist vom Lösungsmittel abhängig. Die Isomeren lagern sich reversibel um; auch in Diäthyläther findet in erheblichem Umfange 1.4‐Addition von Isopren an Lithiumbutyl statt.Während bei −10°C für die Polyreaktion des Isoprens mit Lithiumbutyl als Initiator die Geschwindigkeitskonstanten

gefunden werden, betragen die entsprechenden Werte für die Polyreaktion des Butadiens

Das kinetisch erfaßbare Assoziationsverhalten von Lithiumpolyisoprenyl wird durch

beschrieben, während Lithiumpolybutadienyl durch

beschrieben wird.Die Vermutung, daß primär immer 1.4‐Verknüpfung erfolgt, deren Produkt dann unter der Wirkung des Initiators isomerisiert, wird gestützt durch die Zunahme der 1.4‐cis‐Struktur mit fallender Initiatorkonzentration:

Initiatorkonz.
1.4‐cis‐Struktur

Mol/l
Isopren
Butadien

3·10−2
80%
35%

5·10−5
95%
70%

<10−5
98%
–

Die bewiesene Umlagerung löst den Widerspruch zwischen postuliertem Primärschritt und gefundenen Produktstrukturen. Die Initiatorabhängigkeit der Stereoselektivität wird mit Hilfe einer Geschwindigkeitskonstanten ki, cis = 105 ± 10 I/Mol·sec der Isomerisierungsreaktion simuliert.
Feldionen‐ und Elektronenstoß‐Massenspektrometrie von Polymeren und Copolymeren. II. Polyisobuten, Polystyrol, Polypropen, Polystyrolperoxid, Polyvinylchlorid
Authors: Hummel D. O. , Düssel H. J. , Rübenacker K. 
Published: April 2003

AbstractAls Beispiele für verschiedene Abbaumechanismen wurden Polyisobuten, Polystyrol, Polypropen, Polystyrolperoxid und Polyvinylchlorid in einem Massenspektrometer mit kombinierter Feld‐ und Elektronenstoßionenquelle pyrolysiert. Aus der Zusammensetzung der Primärfragmente lassen sich Abbaumechanismen herleiten, die teilweise noch nicht bekannt waren oder über die bekannten hinausgehen. Der Abbau von Polyisobuten und Polystyrol geschieht durch statistische Kettenbrüche und Retropolymerisation. Die mannigfaltigen Primärfragmente des Polypropens lassen sich durch statistische Kettenbrüche, «back‐biting» und Retropolymerisation erklären. Die thermische Spaltung des Polystyrolperoxids geschieht jeweils zwischen zwei Sauerstoffatomen; die Fragmente stabilisieren sich durch Sekundärreaktionen. Alterungsvorgänge, an diesem Beispiel studiert, lassen sich massenspektrometrisch nachweisen, bevor sie IR‐spektrometrisch manifest werden. Beim PVC wurde gezeigt, daß zahlreiche schwerere Bruchstücke, überwiegend Aromaten und Alkylaromaten, als «Primär»‐Fragmente anzusehen sind.
Calculation of particle sizes in emulsion polymerization systems
Authors: Watterson John Grant , Parts Adolf Gustav 
Published: April 2003

AbstractCalculations of the particle size number distribution resulting from emulsion polymerization have been carried out for a model of the system used previously by the authors. The sum of the lifetimes of the growing molecules which a particle has contained, is used as the measure of its size. The resulting curves indicate an increase in the breadth of the distribution with increasing time.
The influence of irradiation and hydration on the transport properties of isotropic and anisotropic membranes
Authors: Williams J. L. , Schindler A. , Peterlin A. 
Published: April 2003

AbstractThe influence of quaternization on the transport properties of water and sodium chloride under reverse osmosis conditions has been examined for alternating copolymers of styrene and 4‐vinyl pyridine. These results demonstrate quite clearly a linear relationship between log P as a function of salt rejection or reciprocal hydration. Such a relationship seems to be quite general for ionic polymers. Also, results with irradiation demonstrate that tensile properties of these copolymers can be improved by about 60% at an optimum dose of about 9 megarads. In addition, the directional permeability of graded membranes has been demonstrated for an alternating copolymer where a gradient of quaternization was imposed on the membrane. Both the water and salt flux were higher along the quaternization gradient than in the reverse orientation of the membrane.
Etude en solution diluée des propriétés du polystyrène ramifié en étoile
Authors: Meunier Jean‐Claude , van Leemput Robert 
Published: April 2003

AbstractThe solution properties of monodisperse four and six branch star‐polystyrene samples have been investigated by viscosimetry, osmometry and light‐scattering.The ⊖ temperature measured by the temperature dependence of the second virial coefficient in cyclohexane is lower than 34.8°C and the expansion of the coil is decreased by branching.The behaviour of the branched polymer is controlled by the number and the length of the branches and no unique relation exists between hydrodynamic and geometric parameters.Average molecular weight data measured by light‐scattering are systematically lower than those obtained by osmometry.
Vinyl polymerization with dimethylaniline/cupric nitrate system
Authors: Sato Tsuneyuki , Takada Masaki , Otsu Takayuki 
Published: April 2003

AbstractA study of vinyl polymerizations initiated with the system of dimethylaniline (DMA) and cupric [Cu(II)] nitrate has been made. This initiator system was found to induce the polymerization of vinyl monomers having an electron‐attracting substituent such as methyl methacrylate (MMA) and acrylonitrile, but it does not initiate the styrene and vinyl acetate polymerizations. The rate of polymerization (Rp) of MMA with this system was expressed by the following Eqs., depending upon the Cu(II) concentration used:

The apparent activation energy for this polymerization was found to be 16.5 and 14.4 kcal/mole for the above two Cu(II) concn. ranges, respectively. The polymer of MMA obtained by this system was found to contain an endgroup similar to dimethylaniline, probably a methylanilinomethyl group, from the determination of its UV spectrum.
Üuber poly‐[3 (bzw. 5)‐vinyl‐pyrazol‐derivate] und ihr metallionenbindungsvermögen
Authors: Schenck Hans‐Uwe , Manecke Georg 
Published: April 2003

AbstractDurch radikalische Lösungspolymerisation wurden Homopolymere von 3(bzw. 5)‐Vinylpyrazol‐derivaten erhalten und deren Eigenschaften untersucht. Durch Copolymerisation von 2,5 Mol‐% Bis‐[3(bzw. 5)‐vinyl‐5(bzw. 3)‐pyrazolyl]‐keton mit 3(bzw. 5)‐Vinyl‐5(bzw. 3)‐pyrazol‐carbonsäureäthylester (I) bzw. 3(bzw. 5)‐Vinyl‐4.5(bzw.3)‐pyrazol‐dicarbonsäuredimethylester (II) wurden Harze dargestellt, die nur begrenzt quellbar sind und die durch Verseifung in Poly‐[vinyl‐pyrazol‐carbonsäure]‐harze (Harz A1 und Harz A2) überführt wurden. Diese Harze stellen hochkapazitive Chelatharze dar. Es wurde das Metallionenbindungsvermögen für Cu2⊕, Ni2⊕, Zn2⊕ und Mg2⊕ und die Aufnahmegeschwindigkeit in Abhängigkeit vom pH‐Wert im Bereich von pH 1 bis pH 5,5 untersucht.
Intramolecular phase transitions of block copolymers in solution from viscosity — temperature studies
Authors: Urwin J. R. , Girolamo M. 
Published: April 2003

AbstractIntrinsic viscosity against temperature plots for two sequence block copolymers of isoprene and styrene in decalin and methyl cyclohexane confirm the general behaviour of these polymers in preferential solvents. The operative parameters are the mol. wt., composition and ⊖ temperature of the less soluble polymer in the particular solvent. The STOCKMAYER‐FIXMAN relation [η]M = Φ0(A + 0.51 BηM)is obeyed, for a particular composition, at all temperatures, but the unperturbed dimensions in the block appear to drop significantly at temperatures below the transition temperature. Since the constant Φ0 is influenced by the segmental distribution, the drop in unperturbed dimensions may be considered to reflect the conformation change from the phase‐mixed to phase‐separated form. The characteristic ratio, C∞ = 〈r2〉0/nl2, which is calcd. from K in the KUHN‐MARK‐HOUWINK Eq. determined directly from [η]0 (⊖ = 44°C in methyl ethyl ketone) is identical with that obtained by extrapolation using the STOCKMAYER‐FIXMAN relation at 46°C. Moreover, C∞ may be calcd. directly from C∞Block = xC∞PS + (1 − x) C∞PI after taking account of the isomeric composition of the polyisoprene.
Effects of triphenyl phosphite on the radical polymerization of acrylonitrile
Authors: Ogawa Takeshi , Taninaka Takumi , Takada Hiroshi , Minoura Yuji 
Published: April 2003

AbstractIn the polymerization of acrylonitrile initiated with α,α′‐azobisisobutyronitrile, triphenylphosphite exhibited two different effects on the rate of polymerization, a decreasing effect and an increasing effect. The decrease is due to the phosphoranyl radical formed by the addition of a 2‐cyanopropyl radical to triphenylphosphite. The increase is due to the formation of a weak n‐π complex between triphenylphosphite and acrylonitrile, which was confirmed from the UV absorption spectra. Triphenylphosphite had no significant effect on the molecular weight of the polymer. The phosphorus content in the polymer was small (0.02–0.06%), the number of phosphorus units in one polymer chain being 1–4.
Imidazole catalyses in aqueous systems. VII. Enzyme‐like catalytic hydrolyses of phenyl esters by copolymers containing imidazole and carboxylate functions
Authors: Kunitake Toyoki , Shinkai Seiji 
Published: April 2003

AbstractThe catalytic hydrolysis of phenyl esters — 3‐acetoxy‐N‐trimethylanilinium iodide (ANTI), 3‐nonanoyloxy‐N‐trimethylanilinium iodide (NNTI), and p‐acetoxybenzoic acid (ABA) — was conducted at 30°C in an aqueous system using polymer catalysts containing a phenylimidazole unit. The hydrolysis of ABA with a negatively charged polymer catalyst followed second‐order kinetics, whereas the catalytic hydrolysis of the cationic substrates proceeded according to MICHAELIS‐MENTEN kinetics. The cationic substrates appear to be bound at the polymer catalytic site by electrostatic forces when the polymer contained the imidazole and carboxylate functions. The substrate binding behavior of the polymer catalysts was explicable by considering the conformational characteristics of the catalytic site. NNTI showed a binding tendency greater than that of ANTI because of its enhanced hydrophobic character due to the long acyl chain. The presence of the carboxylate group at the catalytic site facilitates the intra‐complex reaction for the cationic substrates.
Syntheses and reactions of functional polymers. LXIII. Syntheses of phenyl polystyryliodonium salts
Authors: Yamada Yorinobu , Okawara Makoto 
Published: April 2003

AbstractThe syntheses of polystyrenes containing iodonium structure were investigated. It was found that phenyl polystyryliodonium bisulfate was quantitatively prepared from polystyrene iodosoacetate and benzene in the presence of conc. sulfuric acid. In a similar way, cross‐linked phenyl‐ and thienyl‐polystyryliodonium salts were synthesized. Anion exchange reaction of phenyl polystyryliodonium bisulfate with sodium bromide and potassium thiocyanate was also studied.
Application of dye techniques in the study of chain‐transfer properties of thiols
Authors: Roy Kamal Kumar , Pramanick Dinabandhu , Palit Santi R. 
Published: April 2003

AbstractDye techniques (dye partition technique in particular) have been found to be simple and sensitive methods for studying the chain transfer properties of substituted thiols containing ionic or ionogenic groups (amenable to dye test). These are: 2‐Mercapto ethanol, 2‐mercapto ethylamine hydrochloride, and thioglycolic acid. Ctr values obtained by this method are found to agree fairly well with those obtained from conventional DP methods. ARRHENIUS parameters and some thermodynamic functions have been evaluated from experimentally determined Ctr values. Existence of a negative temperature coefficient is found for the transfer process of the thiols with PMMA radicals. Transfer potency of the thiols is found to be dependent on their structure. Thus Cs value for 2‐mercapto ethylaminehydrochloride with MMA is found to be least in the present series which can be accounted for the presence of a strong electron accepting group in the thiol which vehemently opposes the electron transfer from the thiol to the electron accpeting PMMA radical in the transition state.
Universal calibration procedures in gel permeation chromatography. Examination of poly(dimethyl siloxane) in a theta solvent
Authors: Dawkins John V. , Hemming Malcolm 
Published: April 2003

AbstractGel permeation chromatography calibrations for polystyrene standards and poly‐(dimethyl siloxane) fractions have been obtained with polystyrene gel using o‐dichlorobenzene at 87°C. Intrinsic viscosity‐molecular weight data show that, at this temperature, o‐dichlorobenzene is a theta solvent for poly(dimethyl siloxane) but a good solvent for polystyrene. The KUHN‐MARK‐HOUWINK exponents are 0.50 and 0.73 for poly(dimethyl siloxane) and polystyrene respectively. This significant difference in polymer/solvent interaction allows assessment of various universal calibration procedures. Comparison of the experimental poly(dimethyl siloxane) data with curves calculated from a polystyrene calibration suggests that the most suitable calibration procedures use the hydrodynamic volume or the perturbed dimensions given by the FLORY‐FOX equation. Calibration procedures based on the unperturbed dimensions or on the perturbed dimensions derived from the PTITSYN‐EIZNER equation are not valid when the difference in the KUHN‐MARK‐HOUWINK exponents is large. For experimental calibrations with fractions, the position of molecular weight and hydrodynamic volume calibrations may depend on the choice of average molecular weight. The influence of fraction polydispersity on the plots is discussed.
An electron spin resonance study of the radiation damage of polysulphone
Authors: Lyons Arthur R. , Symons Martyn C. R. , Yandell John K. 
Published: April 2003

AbstractESR studies of γ‐irradiated polysulphone (prepared from 2.2′‐bis(4‐hydroxyphenyl)‐propane and 4.4′‐dichlorodiphenyl sulphone) and its model compounds (diphenyl sulphone, 2.2′‐diphenyl propane, diphenyl ether), suggest that the majority of radicals produced in the polymer are formed by the subsequent reactions of hydrogen atoms released from the pendant methyl groups by the action of the γ‐radiation. Cyclohexadienyl‐type radicals are produced in quantity together with phenoxy and ArṠO2 radicals. Supporting evidence for the mechanism is obtained from studies of the hydrogen atom bombardment of the polymer.
Aqueous polymerization of acrylamide initiated by acidic thiourea/potassium bromate redox system
Authors: Shukla J. S. , Misra D. C. 
Published: April 2003

AbstractThe aqueous polymerization of acrylamide initiated by bromate/thiourea redox system has been studied in acidic media at 25 ± 0.2°C in a nitrogen atmosphere.The rate of polymerization has been found to vary with the first power of the potassium bromate concentration within the range 0.75·10−2 to 2.0·10−2 mole·1−1 and nearly with the first power of the hydrochloric acid concentration within the range 2.85·10−2 to 8.55·10−2 mole·1−1. However, the rate of polymerization is independent of the thiourea concentration, but varies with the first power of the monomer concentration within the range 6.0·10−2 to 10.0·10−2 mole·1−1. The initial rate increases but the maximum conversion decreases as the temperature increases within the range 19 to 35°C.The over all energy of activation has been found to be 22.9 kcal·mole−1 within the temperature range mentioned above. Water miscible organic solvents and mono‐ and dibasic salts show the same effect as given by MISRA et al. The effect of cationic and anionic surfactants has been found to increase and decrease the rate of polymerization (Rp) respectively, however non‐ionic detergents have no effect on the (Rp).
The asymmetrically selective hydrolysis of phenylalanine esters catalyzed by poly‐L‐lysine/copper(II) complexes
Authors: Nozawa Tunenori , Akimoto Yoshihiro , Hatano Masahiro 
Published: April 2003

AbstractThe poly‐L‐lysine/copper(II) complex was found to exhibit the asymmetrically‐selective catalysis on the hydrolysis of phenylalanine esters at pH 7. The reaction rate showed a first order dependence on the ester concentration for the initial part of the hydrolysis. Tetraaquocopper(II) ion and bis(bipyridyl)copper(II) ion had no catalytic activity on the hydrolysis at pH 7. The catalytic activity was discussed on the basis of the stability constant data of these complexes.
Untersuchungen zur copolymerisation von pyrrolidon und caprolactam
Authors: Schirawski Günter 
Published: April 2003

AbstractPyrrolidon und Caprolactam werden im Temperaturbereich von 70–200°C in Masse anionisch copolymerisiert. Die mit steigender Polymerisationstemperatur abnehmende Polymerisationsneigung des Pyrrolidons führt trotz hoher Monomerkonzentrationen zu immer niedriger liegenden Pyrrolidongehalten. Für 70, 110, 150 und 2OO°C werden die Copolymerisationsparameter ermittelt.
Sequenzanalyse bei trioxocan/dioxolan‐copolymeren durch NMR‐spektroskopie unter zusatz von lanthaniden‐komplexen
Authors: Fleischer Dietrich , Schulz Rolf C. 
Published: April 2003

AbstractZusatz des paramagnetischen Lanthanidenchelats Eu(DPM)3 zur Meßlösung eines Trioxocan/Dioxolan‐Copolymeren ermöglicht im kernmagnetischen Resonanzspektrum die Bestimmung der Bruttozusammensetzung und verschiedener Sequenzen. Das sehr reaktionsfähige Trioxocan (TOC) polymerisiert zu Beginn bevorzugt (rTOC = 78, rDOL = 1,7); Dioxolan (DOL) wird im weiteren Verlauf der Reaktion wahrscheinlich durch Transacetalisierungsreaktionen in das Polymere eingebaut bis zu einer nahezu statistischen Verteilung der Grundbausteine.
Über die Wechselwirkung des Katalysators und Cokatalysators mit dem Monomeren und Polymeren bei der kationischen Polymerisation des Isobutylens. I. Modellstudium der primären Deuterierung und isomerisierung des triisobutylens durch das system AlBr3/DBr
Authors: Kříž Jaroslav , Marek Miroslav 
Published: April 2003

AbstractDer zeitliche Verlauf der Isomerisierung und der Deuterierung in verschiedene Stellungen des 1.1‐Dineopentyläthylens durch das System AlBr3/DBr in Heptan entspricht der Konkurrenz zwischen der Reaktion des Deuterons und der des AlBr3 allein mit dem Substrat. Es wird diskutiert, in welcher Weise dieser Effekt bei der kationischen Polymerisation des Isobutylens zur Geltung kommen kann.
Some reaction variables in the aqueous solution synthesis of titanium polythioethers
Authors: Carraher Charles E. , Nordin Robert J. 
Published: April 2003

AbstractTitanium polythioethers of the form below were prepared from Cp2TiCl2 and dithiols by the solution method.
magnified imageThe following reaction variables were studied and reported on: molar ratios of the base, Cp2TiCl2 and dithiols and concentration of the reactants, stirring time and volume of the aqueous phases.Polymer yield seeks a maximum around a molar ratio of Cp2TiCl2:dithiol:base of 1:1:2.
Electrochemically initiated cationic polymerization of trioxane in acetonitrile. Part I
Authors: Mengoli Giuliano , Vidotto Graziano 
Published: April 2003

AbstractTrioxane, dissolved in acetonitrile solvent containing tetrabutylammonium perchlorate as background electrolyte, has been polymerized under continuous current supply at the anode of an electrolytic cell with separated anodic and cathodic compartments. The polymerization rate and the molecular weight of the polymers obtained are functions of the current intensity and the reaction temperature.At 20°C the reacting system presents a poor autocatalytic trend and may be described by the hypothesis of the steady state for the active species.The thermal stability of the polyoxymethylenes obtained in acetonitrile solvent is improved by the electrochemical copolymerization of trioxane with 1,3‐dioxolane.
Polymerisation of vinyl monomers by transition metal benzyl compounds. Part II. Polymerisation of styrene by tetrabenzyl zirconium
Authors: Ballard D. G. H. , Dawkins J. V. , Key J. M. , Van Lienden P. W. 
Published: April 2003

AbstractThe polymerisation of styrene by tetrabenzyl zirconium in toluene in the dark at 30 and 40°C has been studied using kinetics, spectroscopic and radiochemical techniques. From the data obtained, together with information derived from molecular weight measurements, a mechanism has been obtained which is in accord with the experimental findings. The polymerisation is of the coordinated anionic type in which only one of the four zirconium benzyl bonds is activated for polymerisation. Each active metal centre grows only one chain and is terminated by a β‐hydrogen abstraction process or by a bimolecular reaction involving monomer. Transfer reactions are absent. Only a small fraction of the catalyst participates in polymerisation and the concentration of active polymerisation centres is very low. A complex between tetrabenzyl zirconium and coordinated monomer could not be detected experimentally. Values for the velocity constants for initiation, propagation and termination are determined.
Redox polymerisation, 2. Kinetics of the reaction initiated by the system cyclohexanone/Mn(III)
Authors: Devi N. Ganga , Mahadevan V. 
Published: April 2003

AbstractPolymerisation of acrylonitrile and methyl methacrylate initiated by the system cyclohexanone/Mn(III) has been investigated at 30–35°C in perchloric acid and sulphuric acid media. The kinetics are consistent with the formation of an intermediate complex between the ketone and the oxidant whose decomposition leads to the initiating radical. In perchloric acid the termination is effected by the oxidant whereas in sulphuric acid primary radicals terminate growing chains. Rate and equilibrium constants have been determined and their significance discussed.