bluuebunny/crossref_metadata_2025_split huggingface dataset:
Die Kationische ε‐Caprolactam‐Polymerisation. V. Die quantitative Bestimmung der N‐Acyllactam‐Gruppen bei der Initiierung mit wasserfreien Säuren und die Konzentrationsänderung der Endgruppen während der Polymerisation
Authors: Rothe Manfred , Mazánek Jan 
Published: April 2003

AbstractAls Beitrag zur Aufklärung des Mechanismus der kationischen Caprolactam‐Polymerisation mit wasserfreien Säuren (z. B. HCl) als Initiatoren wurde der Gehalt der C‐terminal entstehenden N‐Acyllactam‐Endgruppen und anderer funktioneller Gruppen der gebildeten Oligo‐ und Polyamide quantitative bestimmt. Dies erfolgte auf IR‐spektroskopischem Wege und durch potentiometrische Titration der nach alkalischer Hydrolyse gebildeten Carboxylgruppen.Für die Polymerisation wurde ein verbessertes Verfahren ausgearbeitet, das vollständigen Sauerstoff‐ und Feuchtigkeitsausschluß ermöglicht und damit besser reproduzierbare Ergebnisse liefert.Die Abhängigkeit der Konzentration verschiedener funktioneller Gruppen von den Polymerisationsbedingungen (Temperatur, Reaktionszeit, Initiatorkonzentration) wurde untersucht. Bei Polymerisationsbeginn entstehen Acyllactam‐ und Ammonium‐Endgruppen in genau gleicher Menge, und zwar je eine der beiden Gruppen pro initiierendes Lactamhydrochlorid‐Molekül. Dies bestätigt den früher1–4 nachgewiesenen Mechanismus der Startreaktion unter Bildung von Oligo‐ε‐aminocaproyl‐caprolactamen. Die Acyllactam‐Konzentration verläuft anschließend durch ein Maximum, sinkt infolge von Nebenreaktionen ab und bleibt danach konstant. Die Konzentration der basichen Endgruppen (als Hydrochloride) bleibt bei höheren Temperaturen nach Erreichen des Gleichgewichts während der gesamten Polymerisation etwa gleich der des eingesetzten Initiators. Die Konzentration an Caprolactam‐hydrochlorid sinkt bis zu einem sehr niedrigen Gleichgewichtswert.Der Reaktionsverlauf hängt stark von der Polymerisationstemperatur ab. Oberhalb 170°C treten zunehmend Nebenreaktionen auf, die zum Verschwinden von Acyllactam‐Gruppen und zur IR‐spektroskopisch nachgewiesenen Bildung von Amidin‐ und Carboxyl‐gruppen führen. Der Anteil der Nebenreaktionen hängt auch von der Acidität des Systems ab.
Syntheses and reactions of ferrocene‐containing polymers. Part IV. Cationic polymerization of 1.1′‐divinylferrocene. Influence of the polymerization condition on the polymer structure
Authors: Kunitake Toyoki , Nakashima Toshihide , Aso Chuji 
Published: April 2003

AbstractCationic cyclopolymerizations of 1.1′‐divinylferrocene with LEWIS acids and alkylaluminum catalysts were performed under various conditions. The cyclization constant rc (the ratio of rate constants of the intramolecular cyclization and the intermolecular propagation) was determined by applying the equation previously empolyed for cyclopolymerizations of o‐divinylbenzene. The rc value (0°C, CH2Cl2) was approximately 1 mole/l. with BF3OEt2, SnCl4, and TiCl4, but increased to 1.8 to 2.8 mole/l. with aluminum‐containing catalysts. It also increased (from 0.67 to 1.49 mole/l.) with increasing polarity of polymerization solvents. The intramolecular cyclization was shown to possess an activation energy higher than that of the intermolecular propagation by 1.2 to 1.5 kcal/mole (AlEtCl2/C6H5CH2Cl, CH2Cl2). These data were interpreted as follows: the intramolecular cyclization of the growing carbonium ion pair becomes more favorable, as the tightness of the ion pair decreases, because of the increase in reactivity. Thermal behaviors of several polymers were examined by differential scanning calorimetry and thermogravimetric analysis, and it was suggested that extensive crosslinking occurred in the molten polymer at about 200°C.
General interpretation of intrinsic viscosity – temperature data and application to solutions of polytetrahydrofuran
Authors: Evans J. M. , Huglin M. B. , Stepto R. F. T. 
Published: April 2003

AbstractThe general form of the variation of In [η] with temperature which results from the excluded‐volume theories of FLORY, KURATA‐STOCKMAYER‐ROIG, PTITSYN, and FIXMAN, is examined. On the basis of these theories a new analysis of ln [η]T versusT data is presented, which enables both d ln 〈r2〉0/dT and the Ψ‐temperature to be evaluated. The procedure has been applied to polytetrahydrofuran in a large number of solvents, and the applicability of excluded‐volume theories to these systems is discussed.
Synthesis and properties of poly[3.3‐bis(mercaptomethyl)oxetane]
Authors: Du Prez E. , Goethals E. J. 
Published: April 2003

AbstractSeveral derivatives of 3.3‐bis(mercaptomethyl)oxetane (BMMO) have been synthesized and their polymerizations studied. Only those derivatives in which the sulfur atoms are substituted by an electron‐withdrawing group (acetate, carbonate, carboethoxy) gave polyethers under the influence of cationic catalysts such as boron trifluoride etherate or phosphorous pentafluoride. Polymers with a degree of polymerization up to 90 were obtained. By alkaline hydrolysis the polymers could be transformed into poly(BMMO). This polymercaptan was soluble only in alkaline medium (alcohol or water). It was oxidized to an insoluble polydisulfide by means of iodine. The rate of oxidation of poly(BMMO) dissolved in 0.5 N sodium hydroxide by means of oxygen in the presence of metal salts has been compared with the rate of oxidation of low molecular weight model compounds and poly(vinyl thiol). It was found that poly(BMMO) always reacted at the lowest rate whereas poly(vinyl thiol) reacted faster than the model compounds if the reaction was first order with respect to thiol concentration but slower if it was of zero order. The lower oxidation rate for the polymers is attributed to steric factors.
Stereospecific polymerization of asymmetric α‐olefins having different optical purity
Authors: Ciardelli F. , Montagnoli G. , Pini D. , Pieroni O. , Carlini C. , Benedetti E. 
Published: April 2003

AbstractThe polymerization of racemic and optically active α‐olefins having optical purity from 10 to 95% has been investigated by several ZIEGLER‐NATTA catalysts. Especially in the case of 3.7‐dimethyl‐1‐octene (I) the polymerization appears to be stereoselective, the predominant antipode being polymerized with higher specific rate. The stereoregularity of polymers from I and from 4‐methyl‐1‐hexene (II) slightly increases with monomer optical purity as shown by solvents extraction, IR spectra, and optical rotation; however a remarkable role is played by the catalytic system.The distribution of R and S units in polymer fractions having different stereoregularity has been also investigated by polymerizing a mixture of (R)‐II and (S)‐II‐1‐14C and possible relationships between stereoregulation and stereoselectivity are discussed.No particular effect of monomer asymmetric structure on polymerization stereochemistry has been observed in the case of 5‐methyl‐1‐heptene (III).
Polymérisations des acrylates de phényle et de p‐crésyle. Structures des polymères
Authors: Gueniffey H. , Pinazzi C. P. 
Published: April 2003

AbstractLes acrylates de phényle et de p‐crésyle ont été polymérisés dans le toluène à −70°C et à +20°C avec le butyllithium comme amorceur, et dans le benzène à +80°C, par l'α.α′‐azodiisobutyronitrile. Les différents polymères ont été soumis à l'hydrolyse basique, estérifiés par CH2N2 en polyacrylates de méthyle, dont les structures ont été déterminées en RMN, puis comparées aux structures des polymères de départ. Les polyacrylates de phényle et de p‐crésyle ont été réduits avec LiAlH4, en alcools polyallyliques et ceux‐ci transformés en polyacétates par action de l'anhydride acétique.
Polymerisation of ethylene with soluble Ziegler‐natta catalysts
Authors: Höcker H. , Saeki K. 
Published: April 2003

AbstractThe polymerisation of ethylene was carried out in the presence of (C5H5)2TiCl2/(C2H5)2AlCl in benzene (I) and of TiCl4/(C2H5)AlCl2in chlorobenzene (II). In the initial state of the polymerisation with I oligomers with a narrow molecular weight distribution are formed. According to their IR and NMR spectra they were identified as predominantly saturated linear hydrocarbons. The effect of a substitution of the cyclopentadienyl rings by R = CH3and C2H5was studied as well as the influence of aging particularly on the molecular weight distribution. The catalytic system II yields predominantly unsaturated branched oligomers with broad molecular weight distribution. The ligand effect on the structure and on the molecular weight of the polymers obtained is discussed.
Radical terpolymerizations of acrylonitrile, vinyl sulfide and vinyl ether. Evaluation of reactivities of vinyl sulfide and vinyl ether toward polyacrylonitrile radical
Authors: Inoue Hiroshi , Otsu Takayuki 
Published: April 2003

AbstractThe co‐ and ter‐polymerizations involving acrylonitrile (M1), vinyl sulfide (M2) and vinyl ether (M3) were investigated to compare the difference in reactivities of vinyl sulfide and vinyl ether toward attack of polyacrylonitrile radical. From the independent copolymerization results for M1/M2 and M1/M3 systems, the reactivity ratio (k12/k13) was determined as 14.7 at 60°C. This ratio was also obtained, from the treatment of the terpolymerization data, as 8.93. On comparison of these values with the previous observation according to which there was a linear relationship between log (k12/k13) and the e values of the M1 monomers, corresponding to the attacking polymer radicals M1•, the values obtained from terpolymerization were found to fit better than those obtained from simple copolymerization. From the ARRHENIUS plot of log (k12/k13), the activation energy for the reaction of ethyl vinyl sulfide with polyacrylonitrile radical was found to be 2.9 kcal/mole lower than that of ethyl vinyl ether.
Vinyl polymerization 270. Polymerization of methyl methacrylate initiated by azibenzil
Authors: Nakaya Tadao , Tanaka Mamoru , Imoto Minoru 
Published: April 2003

AbstractThe polymerization of methyl methacrylate initiated by azibenzil (AB) was studied kinetically. The initial rate of polymerization (Rp) was found to be expressed by the equation Rp = k[AB]0.47[MMA]0.97. The polymerization proceeded through a radical mechanism. The overall activation energy for the polymerization was estimated as 16.1 kcal/mole. Furthermore, the rate of decomposition of AB was measured in benzene and the following rate equation was obtained: kd[sec−1] = 5.75·1010 exp(‐21.9 kcal/RT). From these results the initiation mechanism was discussed.
Zum einfluß der molekularen uneinheitlichkeit auf molekulargewichtsabhängige eigenschaften von polymeren in lösung
Authors: Sutter Wolfgang , Kuppel Adelbert 
Published: April 2003

AbstractDie bei den verschiedenen Verfahren zur Bestimmung der ungestörten Dimensionen in der Literatur verwendeten Uneinheitlichkeitskorrekturen sowie die Beziehung zwischen Mw, MsD und M[η] werden unter Zugrundelegung der Verteilungsfunktion nach SCHULZ‐ZIMM neu berechnet.Die neuen Werte unterscheiden sich von den bisher gebräuchlichen z.T. erheblich, was eine Neuinterpretation der davon betroffenen Literaturdaten nahelegt.
Untersuchungen zum reaktionsverlauf der kationisch initiierten, ringöffnenden copolymerisation von tetrahydrofuran und dicarbonsäureanhydriden
Authors: Öchsner Waldemar , Reichert Karl‐Heinz 
Published: April 2003

AbstractDie kationisch initiierte Reaktion von Tetrahydrofuran (THF) mit Dicarbonsäureanhydriden führt unter ringöffnender Copolymerisation selbst bei Reaktionstemperaturen oberhalb der Ceilingtemperatur des Ringäthers zu Polyätherestern. Der Verlauf der einzelnen Reaktionsschritte der Copolymerisation und der Mechanismus der Wachstumsreaktion wurden durch kinetische Untersuchungen der Copolymerisationsreaktion THF/Bernsteinsäureanhydrid (BSA) sowie einer Modellreaktion THF/Essigsäureanhydrid (ESA) und durch Bestimmung der Zusammensetzung der Reaktionsprodukte ermittelt. Die kinetischen Versuche ergaben, daß der nukleophile Angriff von THF an ein Oxoniumion des Anhydrids die Geschwindigkeit der Wachstumsreaktion bestimmt und daß sich die Reaktivitäten der beiden Anhydrid‐Oxoniumionen gegenüber einem THF‐Angriff um einen Faktor von ca. 25 voneinander unterscheiden (…[−ESA]⊖ > …[−BSA]⊕). Aus der Zusammensetzung der Reaktionsprodukte oberhalb der Ceilingtemperatur von THF konnten die relativen Reaktivitäten der beiden Monomeren, THF und Anhydrid, in den konkurrierenden Anlagerungsschritten an das THF‐Oxoniumion …[−CO‐TH́F]⊕ ermittelt werden. Danach ist BSA um den Faktor 2 reaktiver als ESA.
Asymmetric addition catalyzed by optically active polymers. II.
Authors: Ohashi Shin'Ichi , Inoue Shohei 
Published: April 2003

AbstractIn the asymmetric addition of lauryl mercaptan to methacrylic esters and crotonic esters catalyzed by optically active amine, the optical yield of the products obtained by polymeric amine was higher than that by low molecular weight amines. The influence of the ester residue on the optical yield was remarkable in polymer catalyst system but not so remarkable in low molecular weight catalyst system. The influence of the ester residue on the reaction rate was not so remarkable. The specificity of the polymer catalyst was discussed referring to the reaction mechanism.
Polymerization of styrene by metal acetylacetonate/phenanthroline system
Authors: Kaeriyama Kyoji 
Published: April 2003

AbstractPhenanthroline accelerates the polymerization of styrene by ß‐diketonate chelates of Mn(II), Mn(III), Fe(III), Cu(II), and Co(III), but has no appreciable effect on Ni(II). Phenanthroline retards the polymerization by acetylacetonate chelate of Co(II). The initiating radical is generated by a ligand exchange reaction of Mn tris‐acetylacetonate with o‐phenanthroline. The rate of polymerization is represented as
Rp ∝ [styrene] {[Mn(acac)3][phenanthroline]}1/2The activation energy and frequency factor are 15.9 kcal/mole and 1.1·106 mole/1·sec in the presence of o‐phenanthroline. The values are compared with those without additives and in the presence of pyridine. Initiation mechanisms are proposed.
The kinetics and statistics of sequences during polymer analogous reaction as investigated by computer simulation
Authors: Klesper E. , Gronski W. , Barth V. 
Published: April 2003

AbstractThe behavior of sequences of monomer units during the polymer analogous reaction of a homopolymer to a copolymer is investigated with respect to its kinetics and statistics by simulation with a digital computer. Three basic reactions are presupposed with a reacting monomer unit in the chain being surrounded by none, one, or two already reacted units. The change in the probabilities of the monads, diads, triads, tetrads, and pentads with conversion, or with the number of random number events, is recorded in dependence of the probabilities for the three basic reactions. Sequence probabilities and reaction probabilities are discussed in terms of alternation and blockiness of the copolymers. The relation between the kinetics of the sequences obtained by simulation and by an actual polymer analogous reaction is determined. On an actual polymer analogous reaction the ratios of the reaction rate constants are found by fitting computer simulated curves for the triad probabilities to the experimental triad probabilities. The statistics of the sequences is shown to be non‐MARKOVian, in general. Conditional probabilities of different orders are calculated and compared with each other to find the lowest order necessary to calculate longer sequences with reasonable accuracy.
Über die Polymerisation des Isobutylens durch Aluminiumjodid in Anwesenheit einiger Alkylhalogenide
Authors: Lopour Petr , Pecka Jan , Marek Miroslav 
Published: April 2003

AbstractEs wurde der Einfluß einiger n‐Alkylhalogenide (n‐Butylfluorid, n‐Butylchlorid und n‐Butylbromid) und einiger Benzylhalogenide (Benzylfluorid, Benzylchlorid und Benzylbromid) auf die durch Aluminiumjodid katalysierte Polymerisation des Isobutylens in Heptan studiert. Dabei wurde festgestellt, daß das n‐Butylfluorid und die Benzylhalogenide die Polymerisationsgeschwindigkeit wesentlich erhöhen. Aus der Abhängigkeit der Polymerisationsgeschwindigkeit und der Molekulargewichte der gewonnenen Polymeren von der Konzentration der Alkylhalogenide und des Aluminiumjodids geht hervor, daß die Alkylhalogenide nicht als Cokatalysatoren wirken, sondern daß die Erhöhung der Polymerisationsgeschwindigkeit durch katalytisch aktive Produkte verursacht wird, die durch Halogenaustausch zwischen dem Aluminiumjodid und den Alkylhalogeniden gebildet werden. Die Ergebnisse der vorliegenden Arbeit werden im Zusammenhang mit den Erkenntnissen diskutiert, die über die Polymerisation des Isobutylens mit den aus zwei FRIEDEL‐CRAFTS‐Halogeniden bestehenden Katalysatorsystemen gewonnen wurden.
Annealing behaviour of melt crystallised trans‐1.4‐polyisoprene
Authors: Martuscelli Ezio 
Published: April 2003

AbstractThe annealing behaviour of samples of melt crystallised trans‐1.4‐polyisoprene, containing different percentages of the two solid modifications, was examined. The plots of long‐spacings versus the annealing temperature show a discontinuity at a temperature that has been identified with the melting temperature of the low‐melting modification.The equilibrium melting point Tm0 and the surface free energy σe of the crystallites of the low‐melting modification of trans‐1.4‐polyisoprene has been calculated thermodynamically using the slope method. A value of 78°C and 102 erg·cm−2 is found for Tm0 and σe, respectively.
Magnetic anisotropy effect on the chemical shift of linear hydrocarbons
Authors: Ando Isao , Nishioka Atsuo 
Published: April 2003

AbstractMagnetic bond anisotropy effects on the chemical shifts of linear hydrocarbons were calculated for the terminal methyl and the methylene protons of planar zigzag chains with a number of carbon atoms from 3 to 22. It was found that the methylene protons near the chain end appear at a slightly higher field than these at the middle of the chain, and approach an asymptotic value at lower carbon numbers comparing with those of the middle point. It may be proposed that the tendencies of the observed chemical shifts of some linear hydrocarbons in α‐chloronaphthalene may be interpreted by the existence of some extended conformations of the chains in this solvent.
Production of organometallic polymers by the interfacial technique. XXI. A study of some associated reaction variables in the synthesis of poly[imino‐1.4‐phenyleneimino(dibutylstannylene)]
Authors: Carraher Charles E. , Winter Duane O. 
Published: April 2003

AbstractPolymers of the below form are synthesized via the interfacial polycondensation route.
magnified imageA study has been made of the influence of the nature of the solvents employed and base and reactant concentration. New interfacial solvent systems are presented.
The stabilisation of critically branched polycondensates
Authors: Kálal J. , Gordon M. , Devoy C. 
Published: April 2003

AbstractThe critically branched state of matter (i.e. systems near their gel point), which occupies a central role in biology, is usually observed only fleetingly in synthetic polymers. Well characterised polycondensates of decamethylene glycol (DMG)/benzene 1.3.5‐triacetic acid (BTA) have now been stabilised near gelation by quantitative benzhydrylation of the free carboxyls with diphenyl diazomethane. Such a polymer system, of weight av. mol. wt. about 105 was so stable that it remained unchanged after heating in air to 150°C for two hrs. The bulk viscosity of such liquids is studied as a function of temp. in relation to the WLF transform. The manner in which the isoviscous‐state theory of Tg fails is elucidated. The crystallisation of about two per cent residual DMG causes a sharp a sharp reversible gelation in these liquids, probably because of some sort of interaction between the liquid polycondensate and the crystal surfaces. The tribenzhydryl ester of BTA is a new crystalline compound of mol. wt. about 750.
The alkaline hydrolysis of methyl methacrylate/isoprene copolymers. 1. Influence of copolymer composition on the hydrolysis behaviour
Authors: Bevington J. C. , Ebdon J. R. 
Published: April 2003

AbstractMethyl methacrylate/isoprene copolymers are hydrolysed in an alkaline medium to different degrees depending upon their compositions. The limiting degrees of hydrolysis can be correlated with the calculated distributions of sequences in the copolymers. A small amount of exchange of methoxy groups between methanol and the copolymer accompanies hydrolysis.
The alkaline hydrolysis of methyl methacrylate/isoprene copolymers. 3. Direct detection of the hydrolysed units
Authors: Bevington J. C. , Ebdon J. R. , Mallard D. J. H. 
Published: April 2003

AbstractBromination of methyl methacrylate/isoprene copolymers leads to the formation of γ‐lactone rings between adjacent methacrylate and isoprene units. The limiting degrees of hydrolysis of the methacrylate units in the brominated copolymers are less than those in the untreated samples. This, together with other evidence, provides support for the conclusions about the hydrolysis reached in Part 1.
Die polykondensationsprodukte des phloroglucins mit hexamethylendiamin
Authors: Tokarzewski Ludomir , Pietranek Waclaw 
Published: April 2003

AbstractBei der Polykondensation von Phloroglucin und Hexamethylendiamin in Toluol‐ oder Wasserlösung bildet sich unlösliches, dunkelgrün gefärbtes Harz. Es wurden die mechanischen und einige elektrische Eigenschaften untersucht und die Struktur des Harzes ermittelt.
Investigation on branching of polyvinylchloride
Authors: Rigo A. , Palma G. , Talamini G. 
Published: April 2003

AbstractAn investigation was carried out on branching of polymers obtained by lauroyl‐peroxide or by radiation‐initiated polymerization of vinylchloride. As a result, branching shows no dependence on conversion and could be ascribed, at least partially, to the presence of CH2Cl‐side groups.A reaction mechanism for this type of branching was proposed.
Studies on formaldehyde‐condensation resins. XV. Gelation theory for phenolic resins
Authors: Uragami Tadashi , Oiwa Masayoshi 
Published: April 2003

AbstractThe gelation of phenol with formaldehyde was investigated theoretically in terms of addition‐condensation reactions; the theoretical kinetic equations involving the relations between the extents of reaction of each functional group and the rate constants, the expression for the gel point etc. were derived by considering the distribution of the structural units.The ratio of the rate constant for condensation to that for addition is evaluated by applying a theoretical kinetic equation to the experimental measurements. The ratio of the rate constant for addition of para position of phenolic nucleus to that of ortho position is also determined by combining the kinetic equation, stoichiometric relation, and expression for the gel point. The total yield of resin, the yield of sol, and the number‐average molecular weight of the sol fraction are discussed in some detail.
Molecular fractionation during crystallization and its application to the study of lamellar thickening during isothermal crystallization
Authors: Mehta Aspy , Wunderlich Bernhard 
Published: April 2003

AbstractThe increase of average lamellar thickness of polymer crystals occurring during isothermal crystallization has been ascribed by KAWAI, HOSOI, and KAMIDE1 to the phenomenon of molecular fractionation induced by crystallization. This explanation however, is not in agreement with several experimental observations. These observations are discussed and compared with an earlier explanation proposing fractionation during crystallization followed by crystal thickening.