bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zur berechnung der ungestörten dimensionen von propylen/vinylcopolymeren
Authors: Biskup U. , Cantow H.‐J. 
Published: April 2003

AbstractFür ataktische und isotaktische Copolymere aus Propylen und 1‐Penten, Styrol oder Vinylchlorid wurden mit dem Modell der rotationsisomeren Zustände von FLORY die ungestörten Dimensionen 〈r〉/nl2 berechnet. Dabei wurde jeweils die chemische Zusammensetzung über den gesamten Bereich variiert. 〈r〉/nl2 ist bei allen Copolymeren kleiner als ein mit den Molanteilen gewichteter Mittelwert von 〈r〉/nl2 der zugehörigen Homopolymeren. Die Abhängigkeit von der Sequenzlängenverteilung, die durch das Produkt rA · rB der Copolymerisationsparameter charakterisiert wurde, erweist sich als gering. Dies gilt insbesondere im Bereich rA · rB < 1.
Asymmetric‐selective polymerization of DL‐leucine N‐carboxy anhydride with optically active amines
Authors: Bührer Heinrich G. , Elias Hans‐Georg 
Published: April 2003

AbstractDL‐Leucine N‐carboxy anhydride was polymerized in dioxane, benzene, tetrahydrofuran, butanone, and N,N‐dimethyl formamide at temperatures between 10 and 55°C using 15 optically active primary and secondary amines as initiators. The optical yield of polymer can be described satisfactorily by an ideal copolymerization equation

for monomer conversions between 3 and 94% (R = const). The highest R was found for the initiation with (—)‐L‐proline methyl ester in dioxane at 25°C (R = 1,30). Ten different models are shown to fit the ideal copolymerization equation depending on whether homopropagation, heteropropagation, homoadsorption, and/or heteroadsorption is taken into account. Most reasonable on the basis of other published evidence seems to be a pure or by far dominating homopropagation (kLL = kDD; kLL[P*L] > kDL[P*D]; kDD[P*D] > kLD[P*L]) with a constant concentration of active chain ends with D‐ and L‐configurations, ([PL*] = const; [PD*] = const′; [PL*]/[PD*] ≠ 1) resp. The present nomenclature in this field is discussed.
Copolymerization of γ‐benzyl‐D,L‐glutamate NCA
Authors: Williams Fred D. , Brown Ronald D. 
Published: April 2003

AbstractThe copolymerization of γ‐benzyl D‐ and L‐glutamates has been investigated in dioxane at 25,35,50, and 65°C using hexylamine as initiator. Temperature changes had remarkably little effect on the overall rate constants indicating an activation energy of less than 1 kcal/mol. The rate curves indicated two stages in the polymerization process: an initial reaction of random coil with monomer which was independent of monomer composition and a final reaction between α‐helical polymer and monomer which occurred stereoselectively. The conclusion was reached that the origin of the stereoselectivity was a specific adsorption of monomer at a site between the α‐helical polymer and the “random” three or so end units of each polymer molecule.
Polymerization of oxiranylalkylamines and thiiranylalkylamines derived from achiral and racemic secondary amines
Authors: Huguet Jovanka , Vert Michel , Spassky Nicolas , Selegny Eric 
Published: April 2003

AbstractThe polymerization of N,N‐diethyl‐N‐(oxirane‐2‐ylmethyl)amine (Ia), by initiator systems such as ZnEt2/H2O, ZnEt2/CH3OH, AlEt3/H2O, and others, gives only low molecular weight polymers with low yields. The corresponding thiirane derivative, N,N‐diethyl‐N‐(thiirane‐2‐yl‐methyl)amine (IIa), with the same type of initiators gives high molecular weight polymers which are non‐crystalline contrary to the case of propylene sulfide. Physicochemical properties (UV and IR absorptions, neutralization and gelation during neutralization) of these polymers are studied. Higher homologues of IIa derived from racemic secondary amines R1R2NH are synthesized and polymerized with ZnEt2/H2O. The influence of the substitu ents R1 and R2 on the physical and chemical properties of the polymers is discussed.
Reactive polymers, 5. Synthesis of a 2,3‐epoxypropyl ethyl maleate/fumarate mixture and its copolymerization with styrene and ethylene
Authors: Kurosaki Toshikazu , Shibata Taiji , Iwakura Yoshio 
Published: April 2003

AbstractA mixture of 2,3‐epoxypropyl ethyl maleate and fumarate (4) was obtained from ethyl potassium maleate and 1‐chloro‐2,3‐epoxy propane.Copolymerization of 4 with styrene was carried out and the monomer reactivity ratios were found to be r1 = 0,30 and r2 = 0,05 (M1: styrene, M2: ester 4). Q and e values were found to be 0,55 and 1,28, respectively. Copolymerizations of 4 with ethylene were performed to improve the chemical reactivity of polyethylene, and the reactivity was studied by means of a homogeneous reaction with dibutylamine. The observed kinetic data may be divided into two parts: ko (non‐catalytic rate constant) = 1,75 · 10−5 dm3 mol−1 s−1, kc (product‐induced catalytic rate constant) = 2,25 · 102 dm6 mol−2 s−1 in DMF at 70°C.
Vinyl polymerization, 298. Polymerization of methyl methacrylate initiated by 4‐cyano‐1‐phenyl‐4,5‐dihyro‐1H‐v‐triazole
Authors: Bando Yoshihumi , Nakaya Tadao , Imoto Minoru 
Published: April 2003

AbstractUsing 4‐cyano‐1‐phenyl‐4,5‐dihydro‐1H‐v‐triazole (1) as initiator, the polymerization of methyl methacrylate (MMA) in benzene solution was performed at 75°C. The initial rate of polymerization was proportional to [1]0,43 and [MMA]1,27. The polymerization proceeded by a radical mechanism. The overall activation energy for the polymerization was 71,8 kJ mol−1 (at 65–85°C). The chain‐transfer constant of 1 for MMA was estimated as 0,0 at 75°C. The rate of thermal decomposition of 1 was also measured and the following rate equation was obtained: kd = 6,79 · 1014 exp (−121/RT) s−1 (E in kJ) (at 60–80°C). Based upon the experimental evidence, a mechanism is discussed for the initiation of the polymerization.
Operating conditions for successive precipitational fractionation of macromolecules, 1. Preparative fractionation
Authors: Kamide Kenji , Miyazaki Yukio , Yamaguchi Keiko 
Published: April 2003

AbstractOperating conditions, such as initial concentration, vpo, fraction size, p, in successive precipitational fractionation (SPE), based on solubility, are studied on various polymers having SCHULZ‐ZIMM and WESSLAU distributions, the ratio of weight‐ to number‐average degree of polymerizations, X̄w/X̄n, ranging from 1,1 to 5. The vpo dependence of X̄w/X̄n in the fraction is larger, for the fractions having smaller p and for the fractions which are separated from a broader whole polymer. As p increases, X̄w/X̄n of the polymer remaining in the polymer‐rich phase decreases, passing through a minimum at a specific value of p, pmin, then increases, irrespective of vpo, the type, and breadth of the molecular weight distribution (MWD) of the original polymer. For SCHULZ‐ZIMM type polymers, the standard deviation, σ', of MWD in the polymers in both phases behaves just like X̄w/X̄n with an increase in p. For the WESSLAU type polymers, on the other hand σ' decreases monotonically with increasing p.By SPF it is theoretically impossible for WESSLAU type polymers that the fractions have a smaller σ' compared to that of the original polymer. The X̄w/X̄n of the polymer in a polymerlean phase, separated from a 1,0% solution of a polymer with the WESSLAU distribution (X̄w/X̄n = 5, X̄w = 300) under the conditions of p = 99/100, is extremely small. The fractionation of polymers with large X̄w in a solvent exhibiting a negative concentration dependence of χ is equivalent with that from a more concentrated solution.
Kinetik der umsetzung von butadien mit sec‐butyllithium unter modellbedingungen
Authors: Sgonnik Vladimir , Schadrina Elena , Kalninsch Karl , Erussalimsky Boris 
Published: April 2003

AbstractDie Umsetzung zwischen Butadien (M) und sec‐Butyllithium (BuLi) in einem Isooctangemisch wurde bei hohem BuLi/M‐Verhältnis im Temperaturbereich von −20°C bis +25°C untersucht; die Reaktionskinetik wurde mit Hilfe von IR‐Spektren untersucht. Für die Aktivierungsenergie der Startreaktion ergab sich ein Wert von 50 ± 17 kJ/mol (12 ± 4 kcal/mol), die Geschwindigkeitskonstante der Initiierung wurde bei 10°C zu 1,5 · 10−3 dm3 mol−1 s−1 bestimmt.Die Reaktionsordnung in bezug auf BuLi liegt zwischen 0,8 und 0,9. Dafür scheinen die Mischassoziate vom Typ (BuLi)n · (BuMLi)m verantwortlich zu sein. Ihre Bildung wurde durch die IR‐Spektren einer künstlichen Mischung von sec‐BuLi mit Oligobutadienyllithium bestätigt.
Polymers containing stable free radicals, 4. Preparation of 2,4‐diphenyl‐6‐(3‐maleoyliminophenyl)‐3,4‐dihydro‐s‐tetrazin‐1(2H)‐yl and its anionic polymerization
Authors: Miura Yozo , Kinoshita Masayoshi 
Published: April 2003

Abstract2,4‐Diphenyl‐6‐(3‐maleoyliminophenyl)‐3,4‐dihydro‐s‐tetrazin‐1(2H)‐yl (6) was synthesized and anionically polymerized with a catalytic amount of sodium 1,4‐dihydro‐1,4‐naphthalenediide, with a conversion up to 96%. The polymer was a dark green powder with a content of radical groups of about 58% (based on unit mol), and its relative molecular mass was about 4 800, corresponding to 12 monomeric units.
The dissociation constants of N‐hydroxymethyl‐2,4,6‐triamino‐s‐triazines(methylol melamines) and methylated analogues
Authors: Tashiro Tatsuo , Shimura Yukio 
Published: April 2003

AbstractThe dissociation constants (pKb) of N‐(hydroxymethyl)‐2,4,6‐triamino‐s‐triazines (methylol melamines) (1) and N‐methoxymethyl‐2,4,6‐triamino‐s‐triazines (methylated methylol melamines) (2) were determined by electrometric titration. The pKb values of 1, having an average degree of formaldehyde substitution of n < 3, and of 2, having an average degree of methoxymethyl group substitution of m = 0,2—6,0, were constant in the region between the initial pH and the half neutralization point or its vicinity. On the other hand, the pKb values of 1 having n > 3 increased with decreasing pH. Thus, a different behavior of protonation between 1 and 2 was observed, and the causes were discussed. Linear correlations were found between pKb and n as well as m.
Separation of trans‐1,4, cis‐1,4 and 1,2‐vinyl polybutadienes by thin layer chromatography
Authors: Donkai Nobuo , Murayama Nobumichi , Miyamoto Takeaki , Inagaki Hiroshi 
Published: April 2003

AbstractA study on thin layer chromatographic (TLC) separation of polybutadienes with three different microstructures, namely, trans‐1,4, cis‐1,4, and 1,2‐vinyl, was carried out. An experimental procedure to separate three possible binary mixtures of these polymers into each component species is established in an alternate use of carbon tetrachloride and amyl chloride as developer. Further it is shown that this procedure combined with a two‐dimensional TLC development technique allows to separate the ternary polymer mixture into components. In addition, the chromatographic behavior of so‐called “equibinary” polybutadienes has been investigated using the technique established so far.
Synthèse de polymères étoiles par réaction de polymères ω‐fonctionnels sur des polyisocyanates
Authors: Pinazzi Christian , Esnault Jacques , Lescuyer Gilles , Villette Jean‐Paul , Pleurdeau Alain 
Published: April 2003

AbstractLa présente étude a pour but la réalisation de réseaux macromoléculaires possédant des propriétés viscoélastiques. La synthèse de ces réseaux implique deux étapes: synthèse de polymères fonctionnels possédant des extrémités actives et réaction de condensation sur des agents polyfonctionnels. Afin de déterminer les conditions de ces réactions de condensation, une étude préalable a été réalisée sur des polymères ramifiés en étoile. Ces polymères sont obtenus par réaction d'un polymère ω‐fonctionnel avec un tri‐, tétra‐ ou pentaisocyanate. Les polymères utilisés dans cette étude sont des polyisoprène, polybutadiène, polystyrène, copolymères séquencés diène‐styrène possédant tous une extrémité hydroxyle. La réaction de polymère liquide ω‐monohydroxylé avec des isocyanates conduit, par formation d'uréthanes, à des polymères ramifiés en étoile. La structure de ces polymères étoiles est confirmée par spectrographie de NMR et par détermination des masses moléculaires.
Stabile Polyphenoxyle, 2. Polymerisationsverhalten von Monomeren mit sterisch behinderter, freier oder geschützter phenolischer Hydroxylgruppe
Authors: Braun Dietrich , Meier Bertold 
Published: April 2003

Abstract2,6‐Di(tert‐butyl)‐4‐vinylphenol (1 a), 2,6‐Di(tert‐butyl)‐4‐isopropenyl‐phenol (1 b) und 2,6‐Di(tert‐butyl)‐4‐isopropenylanisol (1 c) sind nur kationisch polymerisierbar. Als Initiatoren können alle Protonen‐ und LEWIS‐Säuren verwendet werden. Eine radikalische oder anionische Polymerisation dieser Monomeren ist erwartungsgemäß nicht möglich.Von den drei untersuchten Monomeren polymerisiert 1 a bei −78°C in Methylenchlorid in sehr kurzer Zeit nahezu vollständig. 1 c kann man unter gleichen Bedingungen nur bis zu Umsätzen von höchstens 28% polymerisieren. Am schlechtesten polymerisiert 1 b, aus dem nur 1 bis 3% hochmolekulare Produkte erhalten werden.Bei der kationischen Copolymerisation von 1 a und von 1 b mit Styrol werden die Phenolmonomeren bevorzugt in die Polymerketten eingebaut. Dieses Verhalten drückt sich in den Copolymerisationsparametern aus: 1 a /Styrol: r1 = 3,4 und r2 = 0,046, 1b/Styrol: r1 = > 1 und r = 0,076.1 a und 1 b zeigen sowohl bei der Homo‐ als auch bei der Copolymerisation immer dann eine Tendenz zur Bildung von vernetzten Polymerisaten, wenn aus den Monomeren bzw. Comonomeren während der Wachstumsreaktion sec‐Carboniumionen gebildet werden können. Dagegen führt die Homopolymerisation von 1 c und 1 b immer zu in Benzol löslichen Polymerisaten. Als Ursache der Vernetzung wird eine Kettenübertragungsreaktion von wachsenden sec‐Makrocarboniumionen mit den Hydroxylgruppen anderer Polymerketten angenommen.
Electrochemically initiated bulk polymerization of trioxane
Authors: Mengoli Giuliano , Vidotto Graziano 
Published: April 2003

AbstractThe electroinitiated bulk polymerization of trioxane containing tetrabutylammonium perchlorate as background electrolyte has been investigated at the temperature of 66,5°C.The polymerization can be started by a very small charge initially supplied and does not present significant termination features.The resulting polymers have high molecular weights, which are dependent on the current amounts, and show satisfactory thermal stability. The species initiating the polymerization is perchloric acid, which is produced by anodic oxidation of the perchlorate ion, followed by hydrogen atom abstraction from trioxane.Bulk trioxane polymerizations catalyzed by added perchloric acid, show in fact similar features as to kinetic chain length, molecular weight of the polymers and polymerization rate, with respect to the electroinitiated trioxane polymerizations.
Cationic polymerization of cyclic sulfides
Authors: Goethals Eric J. 
Published: April 2003

AbstractThe mechanism of the cationic polymerization of cyclic sulfides, initiated with triethyloxonium salts is reported. Differences due to changing the counter‐ion from BF to SbCl are discussed. Initiation consists of the alkylation of monomer forming a cyclic sulfonium ion which is the active species in the propagating step. A generally occurring termination reaction is the formation of non‐strained (linear or cyclic) sulfonium ions. In the case of epithiopropane (propylene sulfide) these can slowly re‐initiate the polymerization by an intramolecular reaction forming the 3‐membered cyclic sulfonium salt. This re‐initiation is not possible with the thietanes because of the greater difficulty to form 4‐membered cyclic sulfonium salts. When SbCl is the counter‐ion, an additional, more drastic termination can occur most probably by reaction of the growing chain with the counter‐ion, thereby forming an alkyl chloride and SbCl5. After the polymerization of propylene sulfide with BF as the counter‐ion, the polymer degrades to low molecular weight oligomers, predominantly the cyclic tetramer. This degradation is a back‐biting reaction occuring via sulfonium salts. With SbCl as the anion, the sulfonium salts are destroyed by the termination reaction and degradation does not occur.It was possible to follow the concentration of the growing species (4‐membered cyclic sulfonium salt) during the polymerization of 3,3‐dimethylthietane by means of 300 MHz NMR spectroscopy. By measuring the rate constants of propagation for different initiator concentrations or in the presence of different amounts of an indifferent electrolyte, it was possible to calculate separate rate constants for propagation via free ions (k) and via ion‐pairs (k). The ratio k/k was about 60 when BF was the anion and 35 when it was SbCl.
13C‐NMR spectra of polyalkenylenes and of some diolefin polymers and copolymers
Authors: Gatti Giuseppe , Carbonaro Antonio 
Published: April 2003

AbstractThe examination of 13C‐NMR spectra of some unsaturated homopolymers (polyalkenylenes and polypentadienes) has shown that it is possible to distinguish beween 1,2‐and 1,4‐structures and between cis‐ and trans‐configuration of the double bonds along the chain. By using this technique, it has been possible to obtain evidences on the structure and the relative orientation of monomeric units in alternating copolymers of isoprene with acrylonitrile or propene. Copolymers of butadiene with these two latter comonomers were also examined by this method.
Synthesis and properties of N‐hydroxymethylcarbamates and their derivatives
Authors: Takeuchi Shigeya 
Published: April 2003

AbstractThe dicarbamates 3a–d were synthesized by the method of Kraft. Their reaction with formaldehyde in the presence of alkali or acid afforded in one case the mono‐N‐hydroxymethyl derivative 4 and with 3a–c the N,N′‐bis(hydroxymethyl) derivatives 5a–c. These were transformed into the corresponding N,N′‐bis(alkoxymethyl) derivatives 6a–f by reaction with alcohols at pH 2,2. The reaction of the N‐hydroxymethylcarbamates with urea afforded urea derivatives of type 9 and 10.
Addition of chlorine and nitrogen dioxide to linear polybutadiene. Degree of isomerization
Authors: Hernández Luis González , Rueda Luis Ibarra 
Published: April 2003

AbstractThe reaction of chlorine or nitrogen dioxide with polybutadiene consists mainly in their addition to the double bonds of the polymer, but it is often followed by a number of secondary reactions, such as crosslinking and cis‐trans isomerization. The addition reaction of nitrogen dioxide is always accompanied by cyclisation.The cis‐trans isomerization, the effect of the solvent nature and catalyst, and the CCl trans‐gauche configuration in the reaction with chlorine were studied by IR spectroscopy.The cis‐trans isomerization, the degree of cyclisation, and the proportion of crosslinked double bonds, in the reaction of nitrogen dioxide were also studied by IR spectroscopy.
Reaction of excited oxygen species with polymer films
Authors: MacCallum James R. , Rankin Clive T. 
Published: April 2003

AbstractThe reaction of atomic oxygen and singlet oxygen molecules with films from various polymeric substrates was studied. The polymers used were poly(vinyl chloride), polyacrylonitrile, polystyrene, nylon 66, and poly(ethylene terephthalate). Atomic oxygen reacted readily with all of these polymers. The reaction was confined to the surface layers which results in the polymer films becoming more hydrophilic. No change was observed in the contact angle of water with films of poly(vinyl chloride) and polystyrene after they had been exposed to singlet oxygen molecules for several hours.
Thermal degradation of some model compounds of PVC
Authors: Varma I. K. , Grover S. S. 
Published: April 2003

AbstractThe liquid phase dehydrochlorination of 1‐chlorododecane (1‐DDCl), 2‐chlorododecane (2‐DDCl), 1,1,3‐trichlorononane (TCN), and dichlorononene (DCN) was investigated in the temperature range of 202—262°C in a nitrogen atmosphere. On the basis of the decomposition rate constant and activation energy the stability order for the dehydrochlorination in liquid phase was found to be 1‐DDCl>2‐DDCl>TCN>DCN. The influence of the solvents methyl salicylate and eugenol on the dehydrochlorination of these chloro compounds was different from their influence on the dehydrochlorination of PVC. Therefore, a molecular mechanism for dehydrochlorination believed to be operating in these chloro compounds may not be operating in PVC degradation.
Die rolle des zentralatoms bei der ringöffnenden polymerisation. Vergleich zwischen wolfram und molybdän
Authors: Lehnert Günther , Maertens Dieter , Pampus Gottfried , Zimmermann Manfred 
Published: April 2003

AbstractDie beiden Katalysatorsysteme aus MoCl5, (ClC4H8)2O, Sn(C2H5)4 und WCl6, (C2H5)2O, Sn(C2H5)4 sind zur ringöffnenden Polymerisation von Cycloolefinen gut geeignet. Anhand der Versuchsergebnisse wird der Einfluß der Zentralatome auf die Bildung der aktiven Spezies erörtert. Zur Erklärung unterschiedlicher Reaktionsweisen wird unter anderem die Raumerfüllung der Metallhybridorbitale diskutiert.
Fonctionalisation des polyalcadiènes: Étude sur molécules modèles des structures accessibles à partir des polymères de l'isoprène par utilisation de l'isocyanate de chlorosulfonyle
Authors: Pinazzi Christian P. , Noireaux Patrick , Reyx Danièle 
Published: April 2003

AbstractLa réaction de l'isocyanate de chlorosulfonyle (1) avec les alcènes permet d'envisager la réalisation de lactames et d'amides N‐chlorosulfonées qui constituent des intermédiaires de synthèse.Dans le but d'obtenir des composés macromoléculaires fonctionnels, nous avons envisagé l'utilisation de cette réaction pour la modification chimique de polyisoprènes de microstructures‐1,4 ou 3,4 prédominantes. Afin de définir les modifications de microstructures provoquées par action de ce réactif, sur ces polymères, nous avons étudié la réaction envisagée sur leurs molécules modèles.Ainsi, il nous a été possible de déterminer les pourcentages de formation de microstructures lactames et amides N‐chlorosulfonées pour chaque type d'enchaînements polyisopréniques. D'autre part, nous avons étudié les transformations des lactames N‐chlorosulfonées en lactames libres, en hydrochlorures d'amino‐acide et en nitriles insaturés.Ce travail permet de définir les références spectrales des microstructures susceptibles de se former lors de l'application aux polymères. Il nous autorise en outre à sélectionner le type d'enchaînement polyisoprénique qu'il conviendra de choisir pour conduire avec plus hauts rendements et la meilleure sélectivité aux composés macromoléculaires fonctionnels recherchés pour des applications spécifiques.
Study of photopolymer, 10. Cationic polymerization of vinyloxyethyl acrylate
Authors: Nishikubo Tadatomi , Kishida Masahiko , Ichijyo Taro , Takaoka Tsuneo 
Published: April 2003

AbstractCationic polymerizations of vinyloxyethyl acrylate (VEA) catalyzed by boron trifluorideether complex were carried out in toluene at 10, −10, and −30°C. In this system, a critical catalyst concentration (C0) exists; when the catalyst concentration is below this concentration, the polymerization of VEA cannot be initiated. The rate of polymerization is expressed as –d[M]/dt=kp(C*)·[M]a, where a was found to be 0,44 (at 10°C), 0.51 (at −10°C), and 0,63 (at −30°C), respectively.From these results, it is concluded that the rate of polymerization of VEA is proportional to the first power of catalyst concentration and to 0,44–0,63 power of monomer concentration between 10 and −30°C, respectively.Furthermore, it is recognized that an increasing monomer concentration tends to decrease the degree of polymerization.
Vinyl polymerization by metal complexes, 17. Effect of nitriles on the vinyl polymerization initiated by imidazole‐copper (II) complex
Authors: Inaki Yoshiaki , Shirai Hirofusa , Takemoto Kiichi 
Published: April 2003

AbstractPolymerization of vinyl monomers initiated by the imidazole‐copper(II) complex was studied in dimethyl sulfoxide solution. Different from the case of acrylonitrile, the polymerization of styrene and methyl methacrylate did not proceed, even in the presence of various sort of nitriles. From these findings and the copolymerization behaviour of acrylonitrile with styrene and methyl methacrylate, together with the spectroscopic data, the presence of acrylonitrile monomer is essential for generating active species to initiate the polymerization.