bluuebunny/crossref_metadata_2025_split huggingface dataset:
Polymères xylyléniques. II. Homopolycondensation des dérivés bis(chlorométhyl) et bis(1‐chloroéthyl) du benzène en présence de catalyseurs friedel‐crafts
Authors: Iovu M. , Tudorache Elena 
Published: April 2003

AbstractDans cd mémoire nous présentons d'une part les résultats de l'homopolycondensation des dérivés bis(chloromeéthyl) du benzène comme 1,4‐bis(chlorométhyl)benzène, en présence des catalyseurs comme: SnCl4, Ticl4 et d'autre part les résultats de l'homopolycondensation des 1,4‐bis(1‐chloroéthyl)benzène et 1,3‐bis(1‐chloroéthyl)benzètne en présence de AlC13 et d'autres catalyseurs.Les rtsultats montrent l'augmentation de la réactivité des dérivés dichlorométhylés dans l'ordre: 1,4‐bis(chlorométhyl)benzène < 1,4‐bis(chlorométhyl)‐2,5‐diméthylbenzène < 1,3‐bis(chlorométhyl)‐4,6‐diméthylbenzène.Le 1,3‐bis(l‐chloroéthyl)benzène a une réactivité similaire au 1,3‐bis(chlorométhyl)‐4,6‐diméthylbenzene, tandis que le l,4‐bis (1‐chloroéthyl)benzène ne peut pas donner des réactions d'homopolycondensation.
Absolute values of the constants of individual steps in the polymerization of methyl methacrylate
Authors: Zafar M. M. , Mahmood Ruquia , Khan Lal , Jilani H. A. 
Published: April 2003

AbstractThe choice of the KUHN‐MARK‐HOUWINK constants, the different ways of evaluating Mn or v̄ from intrinsic viscosity, the selection of ktc/ktd from the literature values and the magnitude of error (±20%) in kp/kt determination may cause by an additive effect a differences of the values of kp and kt by a factor of three to four. The discrepancies in the reported values of the absolute rate constants of the polymerization of methyl methacrylate have been explained by this fact.
Studies on metal chelating polymers, 1. Preparations and properties of the cationic polymers containing the 3‐formyl‐4‐hydroxybenzyl group in the side chain
Authors: Haruta Masami , Kageno Kenji , Harada Susumu 
Published: April 2003

AbstractDiallyl‐(3‐formyl‐4‐hydroxybenzyl)‐methylammonium chloride (I) was prepared. The homopolymerization of I and the copolymerization or terpolymerization of I and other diallyl compounds and/or sulfur dioxide were carried out under various conditions. The effect of the polymerization conditions on the yields and on the inherent viscosities was studied.The structure of sulfur dioxide containing polymers was discussed by means of the nature of thermal stability.The physico‐chemical properties of the polymers were investigated.
Cationic polymerization of cyclic imines. I. 1,3,3‐trimethylazetidine
Authors: Schacht Etienne H. , Goethals Eric J. 
Published: April 2003

AbstractThe polymerization of 1,3,3‐trimethylazetidine (TMA) under the influence of various cationic initiators has been studied.At room temperature no polymers were formed, but at 60°C or higher, polymerization went to complete conversion. The kinetics of the polymerization were studied with triethyloxonium tetrafluoroborate as initiator and nitrobenzene as solvent. The time‐conversion curves showed that the polymerization is of first order with respect to monomer and initiator. From conductivity measurements and model reactions it was concluded that the initiation reaction (alkylation of monomer) is quantitative and instantaneous. Second monomer addition experiments showed that the polymer is of the “living” type. The absence of a termination reaction is attributed to the high basicity of the monomer compared to that of the polymer. At 78°C the rate‐constant of propagation was found to be 1,4 · 10−4 dm3 · mol−1 · s−1. The energy of activation is 19 kcal · mol−1.
Reaktionskinetische untersuchungen an einem makroporösen unquellbaren polystyrol: Abspaltung von nucleosiden und nucleotiden, die über p‐anisyldiphenylmethylätherbindung an das polymerisat gebunden sind
Authors: Köster Hubert , Cramer Friedrich 
Published: April 2003

AbstractEin makroporöses unquellbares Styrol‐Divinylbenzol‐Copolymerisat (I) wird in ein polymeres Derivat des p‐Anisyldiphenylmethylchlorids (VI) übergeführt, das mit den Nucleosiden dT(Ac) (VIIa), dbz6A(Ac) (VIIb) und dem Dinucleosidmonophosphat dT–dT(Ac) (X) veräthert wird. Die Abspaltungsgeschwindigkeit von nucleotidischem Material vom Träger wird in Abhängigkeit von der Art des geschützten oder ungeschützten Nucleosids bzw. Dinucleosidphosphats, von dem bei der Beladung des Trägers vorliegen den Verhältnis von VI zu X und in Abhängigkeit von der Temperatur untersucht. Um vergleichende Untersuchungen dieser heterogenen Reaktionen durchführen zu können, werden zwei Größen eingeführt: die relative Anfangsgeschwindigkeit v beschreibt vorwiegend die Hydrolyse der p‐Anisyldiphenylmethyläther‐Bindung, die relative Geschwindigkeit nach einer Stunde v das komplexe Diffusionsgeschehen innerhalb des verzweigten Hohlraumsystems des Polymerisates.
SCHOTTEN‐BAUMANN esterification of poly(vinyl alcohol). III. Preparation of some photosensitive polymers and the effects of surface active agents on the interfacial esterification
Authors: Tsuda Minoru , Tanaka Hideaki , Tagami Hiroshi , Hori Fumikazu 
Published: April 2003

AbstractSome of the photosensitive polymers, poly(vinyl p‐azidobenzoate), poly(vinyl p‐nitrobenzoate), poly(vinyl 2‐methyl‐5‐phenyl‐2,4‐pentadienoate), and poly(vinyl cinnamate co vinyl cyanoethyl ester), are prepared by SCHOTTEN‐BAUMANN esterification of poly(vinyl alcohol). The preparations of the acid halides and polymers are reported in details. The study of the effects of surface active agents on the esterification process shows the following results. When nonionic and anionic agents were added into the reaction system, the yield of the product increases with decreasing concentration of surface active agents and becomes a linear function of the concentration ending at the point at which no surface active agent is present. The linearity is observed in a wide range of concentration of the anionic agent, but not in the case of the nonionic one. The cationic agent drastically inhibits the reaction even at very low concentrations. These phenomena are explained on the basis of the reaction mechanism proposed in a previous paper.Applying the esterification process to a polyelectrolyte the reaction occurs only in the presence of salts as KBr, NaNO3 etc. This phenomenon is also explained by the reaction mechanism.
Vernetzte polymere mit spaltbaren netzbrücken. III. Polymerisations‐ und spaltungsreaktionen mit 1,2‐bis(4‐vinylphenyl)‐1,2‐äthandiol
Authors: Braun Dietrich , Brendlein Wolfgang 
Published: April 2003

AbstractDie Polymerisation von 1,2‐Bis(4‐vinylphenyl)‐1,2‐äthandiol (DSG) bei niedrigen und höheren Umsätzen sowie Spaltungsreaktionen mit Bleitetraacetat an den entstandenen Polymeren werden beschrieben. Die Parameter der Copolymerisationen von DSG mit Styrol und Methylmethacrylat werden bestimmt. Eine Reihe von Copolymeren aus DSG und Styrol werden zur Ermittlung des Verzweigungsgrades in Abhängigkeit von Umsatz, Gesamtmonomerkonzentration und Vernetzerkonzentration dargestellt und mit Bleitetraacetat gespalten. Aus den Molekulargewichten vor und nach der Spaltung wird die Konzentration der Verzweigungsstellen ermittelt.
Melting points of chlorinated polyethylenes
Authors: Erä Väinö A. 
Published: April 2003

AbstractMelting points of chlorinated polyethylenes (CPE) of varying chlorine contents have been measured by differential scanning calorimetry (DSC). Linear correlations are found between the chlorine content and the melting points. Deviations from theoretical values predicted by FLORY's theory on the melting point depression of random ethylene copolymers are discussed.
13C‐{1H} and 1H NMR spectra of the polymers of four monosubstituted thiiranes
Authors: Ivin Kenneth J. , Lillie Edwin D. , Petersen Ingo H. 
Published: April 2003

AbstractPolymers of four monosubstituted thiiranes (R = CH3, butyl, tert‐butyl, C6H5; X = H, D) were prepared using a variety of anionic and cationic catalysts and investigated by 1H and 13C‐{1H} NMR spectroscopy. Four chemical shifts, corresponding to triad structures, were observed for CH carbons with R = tert‐butyl and C6H5, and for CH2 carbons with R = tert‐butyl; also for both CH2 protons with R = tert‐butyl. Two chemical shifts, corresponding to dyad structures, were observed for side‐chain α‐carbons with R = tert‐butyl and C6H5, and for CH carbons with R = CH3 and butyl. For R = CH3 a good correlation was found between the isotactic dyad content determined from the CH carbon spectrum and the CH2 proton spectrum.The proportion of isotactic dyads (σ) varied only slightly with catalyst for R = butyl (σ = 0,5–0,6), more for R = C6H5 (σ = 0,45–0,7), still more for R = CH3 (σ = 0,5–1,0) and yet more for R = tert‐butyl (σ = 0,4–1,0). In the last case the coupling constants for the main‐chain protons in isotactic polymer were JAB(gem) = 12,5, JBC = 11,5 Hz, indicating a preponderance of distorted trans conformations about the main‐chain CC bonds.For R = CH3 the 13C spectrum provides good evidence of a small proportion of head‐head structures in the polymer, about one unit in six being reversed for Mg(ClO4)2 as catalyst and one in twenty‐five for CdCO3 as catalyst. For R = tert‐butyl there was little sign of such structures.The results are discussed in terms of the mechanism.
Solubilization of a polymer in dilute block copolymer solution
Authors: Tuzar Zdeněk , Kratochíl Pavel 
Published: April 2003

AbstractPolybutadiene was solubilized in dilute solutions of styrene/butadiene/styrene block copolymers in selective solvents for polystyrene. The formed mixed micelles gave rise to a permanent turbidity of the solution. The systems were investigated by viscometry and light scattering. Using simplifying assumptions about the shape of the micelles, the micellar weights (up to 1010) and sizes (particle diameter up to 300 nm), as well as the average volume fractions of the polymer in the space occupied by a micelle (≈ 0,8–1,0) were estimated.
Étude de l'interaction eau/poly(L‐proline), 1. Influence de la teneur en eau sur les propriétés électriques de la poly(L‐proline) (forme II)
Authors: Guillet Jacques , Seytre Gerard , May Jean‐François , Vallet Georges 
Published: April 2003

AbstractCe travail donne les résultats sur les propriétés diélectriques de la polyproline II hydratée aux températures de 35, 42,5, 50,5 et 60,5°C dans une gamme de fréquences de 500 Hz à 3 MHz pour des taux d'hydratation compris entre 0 et 10%. On a pu ainsi mettre en évidence l'existence de deux mécanismes de conduction: un mécanisme de conduction électronique entre 0 et 6% d'eau et un mécanisme à contribution ionique prépondérante pour des teneurs en eau supérieures.Les courbes d'absorption présentent deux bandes: l'une associée à la réorientation de dipǒles dans le champ électrique, l'autre à la polarisation de l'eau liée au polypeptide.
Effect of syndiotacticity on the reaction of poly(vinyl alcohol)s with iodine
Authors: Matsuzawa Shuji , Yamaura Kazuo , Noguchi Hiroji 
Published: April 2003

AbstractPoly(vinyl alcohol)s derived from poly(vinyl trifluoroacetate), obtained by free radical polymerization of vinyl trifluoroacetate in various kinds of solvents at temperatures between 60 and −40°C, are reacted with iodine in aqueous solution, and UV‐spectra of the solutions were measured after the reaction. The absorption maximum in the UV‐spectrum appears at 600 nm for the polymers obtained in ketones, alkanes, and esters or at 590 nm in aldehydes. The absorbance of the maximum increases with increasing syndiotacticity up to a content of syndiotactic diads of Xs ≈︁ 55,5–58,5% or of triads of Xss ≈︁ 34,2–39,3%, then it passes through a maximum value and decreases with increasing Xs or Xss. It is considered that the increases is due to the stereoregularity of the PVA molecules and that the decrease is due to the formation of microgels in solution.
Synthesis of poly[4(5)‐vinylimidazole‐co‐γ‐vinyl‐γ‐butyro‐lactone] and its catalytic activity in ester hydrolysis
Authors: Shimidzu Takeo , Furuta Akihiro , Watanabe Tadanori , Kato Shigekí 
Published: April 2003

AbstractCopolymerizations of 4(5)‐vinylimidazole (1) and γ‐vinyl‐γ‐butyrolactone (2) initiated by 2,2′‐azoisobutyronitrile or benzoyl peroxide were carried out. The initiators did not affect the radical reactivity ratio (r). In addition, the reactivity ratio was not influenced by methanol as solvent. The following ratios were obtained r1 = 20,0 ± 0,8 and r2 = 0,030 ± 0,002.The catalytic activity of the copolymers in the hydrolyses of p‐nitrophenyl acetate (4) and 3‐acetoxy‐N,N,N‐trimethylanilinium iodide (5) at pH = 8,0 was found to be more than twice as high as that of a random terpolymer containing imidazole, carboxylic acid, and hydroxy moieties.
Crystallization of polypeptides in the course of polymerization, 5. Effect of the steric hindrance on the crystal growth by the side chains
Authors: Kōmoto Tadashi , Kim Kea Yong , Ōya Masanao , Kawai Tōru 
Published: April 2003

AbstractIn order to examine the effect of the steric hindrance by the polypeptide side chains on the growth mechanism of polypeptide crystals in the course of polymerization, we studied kinetics of the heterogeneous polymerization of L‐valine N‐carboxy anhydride (NCA), L‐isoleucine NCA, and L‐leucine NCA initiated by butylamine in acetonitrile and the structures and morphologies of the resultant polymers. In the early stages of polymerization, oligomers formed crystallized into thin ribbon‐like crystals with the antiparallel β‐conformation. The molecular arrangements in the crystals were studied by electron diffractions. In the later stages, the grown chains of poly(L‐valine) and poly(L‐isoleucine) continued to take the β‐structure and their active ends were occluded in the crystals formed, which resulted in the levelling off of the conversion at a low value. On the other hand, poly(L‐leucine) seemed to give the extended chain crystal, which made the conversion very high. This can not be accounted for without assuming the formation of β‐helical chains onto the β‐skeleton crystals formed in the early stages of polymerization as in the case of poly(L‐alanine) reported previously.
Increase of the crystallite size by application of tensile stress for highly oriented polymer
Authors: Kaji Keisuke 
Published: April 2003

AbstractThe change of the crystallite size in the chain‐axial direction by application of tensile stress was investigated for highly oriented nylon 6 (α and γ) fibers. The crystallite sizes were determined from the line widths of the X‐ray meridional reflections using the method of HOSEMANN and WILKE.In both, the α‐ and γ‐forms the crystallite size increases with the applied stress and levels off when it approaches the initial long spacing. This result can be interpreted by the fringed micell fibrillar model with crystalline regions alternating between amorphous regions; the crystallites grow at the expense of the amorphous regions retire into the intercrystallite regions in the fibril with the applied stress. In fact this was supported by the analysis of the small angle X‐ray scattering intensities.
Mechanochemische Synthesen durch Polykondensation mit Polyestern als Grundsubstanz, 3. Einige kinetische Aspekte der Mechanochemischen Polykondensation durch Schwingmahlung des Poly(oxyäthylenoxyterephthaloyl)s mit aliphatischen Diaminen
Authors: Neguleanu Claudia , Oprea Cleopatra Vasiliu , Simionescu Cristofor 
Published: April 2003

AbstractKinetik und Mechanismus des mechanochemischen Polykondensationsvorganges von Poly(oxyäthylenoxyterephthaloyl) (Polyäthylenterephthalat) mit aliphatischen Diaminen (äthylen‐ und Hexamethylendiamin) wurden untersucht. Es wurde gefunden, daß die Reaktion nach einer Kinetik erster Ordnung abläuft, daß eine äußerst geringe thermische Aktivierungsenergie benötigt wird und daß die Diamine als Radikalakzeptoren auftreten können.
Neuere Erkenntnisse zur Polymerisation von Blausäure
Authors: Lotz Werner , Donner David B. , Ferris James P. 
Published: April 2003

AbstractFür die Polymerisation der Blausäure werden zwei grundsätzlich verschiedene Mechanismen diskutiert, von denen einer den schrittweisen Aufbau des Polymeren, ausgehend von Blausäure als Monomerem, vorsieht, während der andere auf dem Dimeren der Blausäure als dem eigentlichen polymerisierenden „Monomeren”︁ beruht. Für die „Dimerpolymerisation”︁ wird neben dem anionischen noch ein carbenoider Mechanismus in Betracht gezogen.Es wurden verschiedene N‐Alkyl‐substituierte Blausäuredimere hergestellt. Sie zeigten keinen Carbencharakter und waren relativ stabil. Ihre Umsetzungen mit Blausäure wurden studiert. Dabei wurde eine Reihe von Additionsprodukten erhalten, die weitgehend den schrittweisen Polymerisationsmechanismus favorisieren.
Studies on the mechanism of redox polymerization initiated by N‐haloamines and iron(II)
Authors: Banthia Ajit K. , Mandal Broja M. , Palit Santi R. 
Published: April 2003

AbstractThe mechanism of the redox polymerization of methyl methacrylate in aqueous medium in the dark was studied for the redox initiator systems N‐halodiethylamine + Fe(II) and triethylamine + halogen + Fe(II), by analysis of the polymer end groups using the dye partition method. In the case of chlorine, both these initiator systems incorporate only the amino group into the polymer to an extent of about one group per polymer molecule. The polymers are found to be free from chlorine. Furthermore, a large portion of the total amino groups introduced into the polymer, using the initiator system triethylamine + halogen + Fe(II) are quaternary in nature. In the case of bromine, both the initiator systems introduce only a bromine atom and no amino group into the polymer. The initiator systems containing chlorine prove to be useful for the preparation of polymers containing amino groups at the one end only.
Die Bildung von Dimetalloalkylenen, eine unvermeidliche Nebenreaktion homogener ZIEGLER‐Katalysatoren
Authors: Kaminsky Walter , Vollmer Hans‐Jürgen , Heins Erhard , Sinn Hansjörg 
Published: April 2003

AbstractDurch konsequente Massenbilanzierungen, Quenchversuche mit Deuteriumchlorid, kinetische Untersuchungen und Kernresonanz‐Messungen konnten in den homogenen ZIEGLER‐Katalysatorsystemen auf der Basis von Bis(cyclopentadienyl)zirkon‐ bzw. ‐titan‐Verbindungen und Aluminiumtrialkylen Kondensationsreaktionen aufgezeigt werden, die im Sinne von Schema 1 unter β‐Wasserstoffübergang und Alkanabspaltung zu Dimetalloalkylenen führen. Zumindest ein Teil der Alterungsvorgänge von homogenen wie heterogenen ZIEGLER‐Katalysatoren läßt sich mit Hilfe dieser Reaktion erklären.
Free radical polymerization of unconjugated dienes, 14. Divinyl ketone in acetone solution at 50°C
Authors: Guaita Marino , Camino Giovanni , Chiantore Oscar , Revellino Mario , Trossarelli Luigi 
Published: April 2003

AbstractThe free radical polymerization of divinyl ketone at 50°C in acetone solutions was investigated. The results are compared with those already reported for the free radical polymerization of other 1,4‐dienes. It is shown that divinyl ketone undergoes bicyclic cyclopolymerization in a similar way as divinyl ether and divinyl sulfide. The cyclization ratios are computed and the polymer composition, in terms of linear, monocyclic and bicyclic structural units, is calculated as a function of the monomer concentration at which the polymerization was carried out.
Emulsion polymerization of styrene with sodium hexadecyl sulphate/hexadecanol mixtures as emulsifiers. Initiation in monomer droplets
Authors: Ugelstad John , Hansen Finn Knut , Lange Svein 
Published: April 2003

AbstractPart 1 describes the emulsification of styrene with mixtures of sodium hexadecyl sulphate (SHS), and hexadecanol (HD). Addition of HD led to a much better emulsification than with the anionic emulsifier alone. The effect of the fatty alcohol depended strongly upon the method of preparation of the emulsion. To obtain a fine dispersion of styrene it was necessary to treat the anionic emulsifier and the fatty alcohol with water at an elevated temperature prior to the addition of styrene. In this way emulsions with droplet sizes in the range of 0,5–1 μm could be prepared with relatively small amounts of fatty alcohol and with moderate stirring. The finely dispersed monomer emulsions produced by this method were capable of adsorbing the major part of the anionic emulsifier.Part 2 describes emulsion polymerization experiments with mixtures of SHS and HD. With emulsifier systems providing the most effective emulsification, the monomer droplets became the main loci for particle initiation and polymerization. Evidence for this hypothesis was provided by the bimodal dispersion of the latex particles, the major part being particles with a size distribution similar to that of the monomer droplet emulsion. The results of the kinetic investigations provided additional arguments for a mechanism involving initiation and polymerization in monomer droplets.
Copolymer statistics during esterification of syndiotactic poly(methacrylic acid) with diazomethane
Authors: Klesper Ernst , Strasilla Dieter , Regel Walter 
Published: April 2003

AbstractSyndiotactic poly(methacrylic acid) is partially esterified as such or in its neutralized form with diazomethane. The extent of reaction and the triad distribution of the resulting cosyndiotactic methyl methacrylate‐methacrylic acid copolymers and their fractions are determined by 1H‐NMR spectroscopy. Unneutralized poly(methacrylic acid) yields copolymers which are heterogeneous with respect to conversion, the fractions of the copolymers possessing an approximate BERNOULLIan triad distribution. Neutralized poly(methacrylic acid) results in homogeneous copolymers whose triad distribution is BERNOULLIan within accuracy of measurement. A kinetic neighboring group effect is therefore not operative during the esterification with diazomethane. Copolymers may thus be prepared which are of simple configurational and compositional statistics, not obtainable at present by copolymerization of monomers. The polyelectrolyte character of the copolymers may be eliminated by consecutive, complete esterification with a second diazoalkane, the statistics of the derived copolymers being identical with that of the precursor copolymers.
Copolymer statistics during esterification of syndiotactic poly(methacrylic acid) with diazotoluene and diazodiphenylmethane
Authors: Strasilla Dieter , Klesper Ernst 
Published: April 2003

AbstractSyndiotactic poly(methacrylic acid) has been partially esterified with diazotoluene or diazodiphenylmethane in extension of work carried out with diazomethane1. The sequence statistics of the resulting cosyndiotactic benzyl methacrylate–methacrylic acid and diphenylmethyl methacrylate–methacrylic acid copolymers have been studied with 1H‐NMR spectroscopy, by relating the triad probabilities obtained by employing different NMR solvents. For both types of copolymers BERNOULLIan triad statistics were found within accuracy of the NMR measurements. Therefore, these polymer analogous reactions, like the reaction of diazomethane with syndiotactic poly(methacrylic acid)1, are not influenced by a kinetic neighboring group effect, despite the greater space requirement of the two diazoalkanes when compared to diazomethane. The copolymers possess therefore a simple, and defined configurational and compositional structure which cannot be obtained at present by the copolymerization of monomers. The polyelectrolyte character of the copolymers could be eliminated without altering the configurational and compositional statistics by complete esterification with a second diazoalkane. Thus the diphenylmethyl methacrylate–methacrylic acid copolymers were converted with diazomethane to diphenylmethyl methacrylate–methyl methacrylate copolymers and with diazotoluene to diphenylmethyl methacrylate–benzyl methacrylate copolymers. Furthermore, it appears that the reaction with syndiotactic poly(methacrylic acid) may also be utilized to prepare defined cosyndiotactic copolymers composed of three or four different types of monomeric units by successive partial esterification with different diazoalkanes.