bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vinyl polymerization. 280. Anionic polymerization of acryloyl‐ and methacryloyl verdazyls
Authors: Miura Yozo , Kinoshita Masayoshi , Imoto Minoru 
Published: April 2003

Abstract1.5‐Diphenyl‐3‐(p‐methacryloyloxymethylphenyl) verdazyl (I), 1.5‐diphenyl‐3‐(p‐methacryloyloxyphenyl) verdazyl (II), and 1.5‐diphenyl‐3‐(p‐acryloyloxymethylphenyl) verdazyl (III) were synthesized and anionically polymerized with n‐butylmagnesium bromide or sodium naphthalene as an initiator to dark green polymers of a molecular weight of about 2300. III was polymerized with a catalytic amount of initiator, while I needed more initiator than the molar equivalent of the monomers suggesting the formation of intermediate metal salts of monomers and subsequent polymerization of the salts. More reactive double bond of III polymerized directly without the formation of the salt between stable free radical and organometallic compounds. Polymeric verdazyls contained up to 68% stable free radical.
Studies of the polymerization of vinyl compounds in the presence of metal salts. 7. Effect of nitric acid on the polymerization of acrylamide initiated by ceric salt
Authors: Narita Hiroshi , Okimoto Tomoyuki , Machida Seishi 
Published: April 2003

AbstractThe polymerization of acrylamide initiated by ammonium cerium(IV) nitrate was investigated. The rate was found to vary with concentration of nitric acid. One factor for the variation is the change of concentration of active species of ceric ion by the acid and another factor is the decrease in activity of acrylamide, because the equilibrium constant for the complex of acrylamide with ceric ion decreased with increasing concentration of acid. The rate of initiation was decided by the increasing of activity of ceric ion and by decreasing of that of monomer. The rate of termination was found to increase with increasing activity of ceric ion. From these results, the structure of the complex was proposed; the ceric ion is considered to be coordinated to carbonyl oxygen rather than double bond in acrylamide.
Reconstructive denaturation of proteins by sodium by sodium dodecyl sulfate. Circular dichroism of soybean trypsin inhibitor, papain and a mold protease
Authors: Jirgensons Bruno 
Published: April 2003

AbstractCircular dichroism (CD) of solutions of soybean trypsin inhibitor (STI), papain, and an acid mold protease (from Rhizopus chinensis) was determined in the presence and absence of sodium dodecyl sulfate (SDS). The CD bands in the 240–320 nm spectral zone were almost completely eliminated by SDS. This indicated that the tertiary folding was disturbed and the restrictions imposed on the aromatic chromophores were largely removed. The CD bands in the far UV were modified by SDS in a manner that indicated increase of the α‐helix content in these proteins. This specific type of denaturation has been observed also on many other proteins. The term reconstructive denaturation is suggested for this type of denaturation in which the helix content of the polypeptide chain is enhanced by the denaturing agent.
A kinetic study of acrylamide polymerization initiated by 4.4′‐azo‐bis‐4‐cyanopentanoic acid in aqueous solution
Authors: Baer Michael , Caskey Jerry A. , Fricke Arthur L. 
Published: April 2003

AbstractA dilatometer was constructed to study the free radical polymerization kinetics of acrylamide below 0.1 M monomer. The polymerization was initiated by 4.4′‐azo‐bis‐4‐cyano‐pentanoic acid in aqueous solution at 25°C.The fkd value, calculated from dilatometric and viscometric data for a test with initial concentration [M] = 0.093 M and [I] = 2.09·10−3 M, was 2.81·10−8 sec−1. Comparison with an extrapolated literature value for kd at 25°C indicated an efficiency value, f, equal to 0.65. Both fkd and f were comparable in magnitude to results of other cited investigations.The results of a 3/2 order dependency of polymerization rate on [M] substantiated the apparent tendency of acrylamide concentration exponents to increase above 1.0 below 0.1 M monomer. A cage effect theory was offered as an explanation for this phenomenon.
Diffusion of gases in poly(methyl methacrylate)
Authors: Patel V. M. , Patel C. K. , Patel K. C. , Patel R. D. 
Published: April 2003

AbstractDiffusion of helium, oxygen, nitrogen, and carbon dioxide in poly(methyl methacrylate) has been studied. The data are analyzed employing the new modified time‐lag technique developed by PAUL and DIBENEDETTO. Different thermodynamic parameters have been evaluated and the mechanism of gaseous diffusion has been discussed.
Rheologische untersuchungen an polymethylmethacrylat‐Lösungen und ihre interpretation nach dem modell der netzwerk‐Lösung
Authors: Lederer K. , Schurz J. 
Published: April 2003

AbstractViskositätsmessungen an Lösungen von Polymethylmethacrylat in Toluol werden nach dem Modell der Netzwerk‐Lösung ausgewertet. Zum Vergleich wird für dasselbe System eine numerische Berechnung der von BUECHE angegebenen Beziehung durchgeführt; es ergibt sich im η0–M‐Verlauf kein Knick, sondern ein Übergang, dessen Breite unter anderem von dem Schlüpffaktor s abhängt. Der Vergleich von Rechnung und Meßdaten ergibt einen vernünftigen Wert des Segment‐Reibungsfaktors f0. Aus den Meßwerten wird weiter das kritische Molekulargewicht Mc ermittelt und daraus das scheinbare statistische Fadenelement A′m, das mit Werten aus anderen Messungen befriedigend übereinstimmt.
Etude de la cristallisation des polymères VIII. Phénomène d'adsorption à la surface des lamelles de polyoxyéthylènes de faible masse moléculaire
Authors: Mathis André , Thierry Annette , Terrisse Jean , Skoulios Antoine 
Published: April 2003

AbstractOn a étudié le gonflement de l'édifice lamellaire d'un polyoxyéthylène de faible masse moléculaire en présence de divers solvants. La technique employée est la diffraction des rayons X aux petits angles de BRAGG.Lorsque les molécules du polymère sont terminées par des groupes OH, le gonflement est d'autant plus important que le solvant utilisé présente un coefficient plus élevé d'étalement sur l'eau et peut davantage former des liaisons hydrogène.Lorsqu'on remplace les fonctions OH terminales par des fonctions Cl ou OCOCH3, le gonflement s'atténue de façon significative.
Preparation of polyarylates with methyl‐di(p‐carboxyphenoxymethyl)phosphine oxide acid chloride
Authors: Borissov Georgi , Sivriev Hristo 
Published: April 2003

AbstractPolyarylates were prepared from methyl‐di(p‐carboxyphenoxymethyl)phosphine oxide (MCPO) acid chloride and bis‐phenols by the interphase polycondensation method
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The highest molecular weights were obtained at an MCPO acid chloride concentration of 0.1 mole·l−1 and a concentration of the bisphenol of 0.05 mole · l−1. Copolyarylates were also synthesized from 2.2‐bis(p‐hydroxyphenyl)propane, MCPO and terephthalic acid chloride employing different mole ratios of monomers. The homo‐ and copolyarylates obtained possess well expressed self‐extinguishing properties and enhanced thermostability.
Synthese neuer ungesättigter comonomerer und ihre copolymerisation mit acrylnitril
Authors: Bahr Ulrich , Wieden Horst , Rinkler Heinrich‐August , Nischk Günther 
Published: April 2003

AbstractZur Copolymerisation mit Acrylnitril wurden neue Monomere mit einer H2CC(R)CObzw. H2CC(CH3)C6H4‐Gruppe einerseits und einer tertiären Amino‐Gruppe, einem Pyridyl‐Rest, einer Carbonsäure‐hydrazid‐Gruppe CONHNRR′, einer Oxalsäure‐hydrazid‐Gruppe COCONHNRR′ oder einer Semicarbazid‐Gruppe NHCONHNRR′ andererseits hergestellt. Ein Teil dieser Verbindungen wurde durch Umsetzung mit Dimethylsulfat, p‐Toluolsulfonsäuremethylester oder cyclischen Sultonen in entsprechende quartäre Ammoniumsalze bzw. Sulfobetaine überführt. Durch Copolymerisation dieser Monomeren mit Acrylnitril wurden Copolymere mit verbesserter Anfärbbarkeit und erhöhter Wasseraufnahme erhalten.
Spectres de résonance paramagnétique électronique des catalyseurs de polymérisation à base de TiCl3. I. Etude expérimentale
Authors: Girard Y. , Che M. , Guyot A. , Chanzy H. 
Published: April 2003

AbstractOn a procédé à l'étude des signaux de résonance paramagnétique életronique (RPE) de catalyseurs de polymérisation industriels à base de TiCl3 avant et après attaque par le triisobutylaluminium (TIBA) en solution dans l'heptane. Selon la nature des échantillons, les spectres comportent un signal étroit à g = 1,94 et éventuellement un signal large à g = 1,84 ± 0,02. Ce dernier paraǐt caractéristique d'une attaque superficielle par l'eau atmosphérique. L'attaque par le TIBA provoque un processus d'extraction et de reprécipitation de composés du titane et une forte alcoylation de la surface, accompagnée par un dégagement important d'hydrocarbures. Elle modifie peu les caractéristiques du signal étroit et fait apparaǐtre, si elle reste modérée, de nouveaux signaux (g = 1,98).Il n'y a cependant pas de corrélation entre ces signaux et l'activité catalytique du solide préalablement lavé et utilisé ensuite avec Al(C2H5)2Cl pour polymériser le propène.
Étude de la cristallisation des copolymères triséquencés poly‐ε‐caprolactone/polyoxyéthylène/poly‐ε‐caprolactone. II. Copolymères dont les séquences ont des longueurs voisines
Authors: Perret Rémi , Skoulios Antoine 
Published: April 2003

AbstractOn a étudié la structure et la cristallisation d'un copolymère triséquencé poly‐ε‐caprolactone/polyoxyéthylène/poly‐ε‐caprolactone, dont les séquences, toutes capables de cristalliser, ont des longueurs équivalentes.Grǎce à la dilatométrie et à la diffractométrie selon DEBYE‐SCHERRER, on a montré que les deux types de séquences cristallisent effectivement et dans un ordre qui dépend de la température de l'expérience. On a défini trois domaines de température: au‐dessous de 51°C, c'est le polyoxyéthylène qui cristallise en premier; au‐dessus de 52°C, c'est au contraire la polycaprolactone qui cristallise en premier; entre 51 et 52°C enfin les deux séquences semblent cristalliser en měme temps.A l'aide de la diffractométrie aux petits angles de BRAGG, on a montré que la structure du copolymère est lamellaire et correspond à l'empilement périodique et alterné de couches de polyoxyéthylène et de polycaprolactone. On a de plus établi que, dans la zone intermédiaire de températures de cristallisation, le système résulte de la juxtaposition de domaines entiers comportant des lamelles soit du type de celles obtenues au‐dessous de 51°C, soit du type de celles obtenues au‐dessus de 52°C.En calculant les taux de cristallinité respectifs des deux séquences du copolymère, on a constaté que ceux‐ci ne sont élevés, et en tout cas comparables à ceux des homopolymères correspondants, que dans la mesure où les séquences considérées ont cristallisé avant les autres.Dans une tentative de description plus détaillée de la structure, on a calculé les épaisseurs respectives des couches de polyoxyéthylène et de polycaprolactone, et, dans chacune d'elles, des sous‐couches de polymère cristallin et amorphe.En étudiant par dilatométrie la fusion du copolymère, on a constaté que les deux types de séquences fondent indépendamment, d'abord les séquences de polyoxyéthylène, puis celles de caprolactone.Dans une dernière partie, on a considéré enfin le phénomène de recuit. Par suite de la fusion précoce du polyoxyéthylène et de la lenteur extrěme de la polycaprolactone à recuire, le copolymère n'évolue guère par chauffage à température élevée.
The synthesis of diols based on the dimer of butadiene
Authors: Burgess F. J. , Cunliffe A. V. , Richards D. H. 
Published: April 2003

AbstractIt has been shown that the reaction of equimolar quantities of butadiene and epoxide with alkali metal in tetrahydrofuran results in the formation of the dimer diol

on subsequent hydrolysis. Yields up to 70% have been obtained with lithium metal, but with sodium the reaction is less efficient.
The thermal degradation of poly(oxycarbonylethylene) (poly‐β‐propiolactone)
Authors: Iwabuchi Susumu , Jaacks Volker , Galil Fahmy , Kern Werner 
Published: April 2003

AbstractThe thermal degradation of poly(oxycarbonylethylene) (poly‐β‐propiolactone) has been investigated within a temperature range of 180–220°C and under various pressures. The degradation begins with a considerable decrease in molecular weight, followed by an accelerating formation of acrylic acid. The reaction involves the following steps:

Random chain scission of polymer chains by typical ester pyrolysis with the formation of fragments one of which containing a carboxylic group the other one a CC‐double bond at the chain end (Eq. (1)).
Formation of the volatile acrylic acid by scissions at the chain end, the amount of acrylic acid or the weight‐loss increasing with the number of fragmentations (Eq. (2)).
Autocatalysed acidic cleavage of the polyester fragments into an α,β‐unsaturated ester and an acid as shown with low molecular model compounds (Eq. (8)).
Substitution of the labile α‐hydrogen atoms in poly(oxycarbonylethylene) by methyl groups—such as in poly(oxycarbonyl‐1,1‐dimethylethylene)—reduces the rate of degradation drastically. This observation together with the results obtained in the pyrolysis of the low‐molecular model compounds, ethyl β‐acetoxypropionate and β‐acetoxypropionic acid, support the postulated mechanism.
Kinetics and mechanism of the polymerization of cyclic acetals initiated by stable carbenium salts. II. Confirmation of the initiation mechanism for triphenylmethyl hexachloroantimonate in the polymerization of 1,3‐dioxolan
Authors: Penczek Stanisław , Kubisa Przemysław 
Published: April 2003

AbstractThe interaction of triphenylmethyl hexachloroantimonate (I) with 1,3‐dioxolan (II) gives the corresponding dioxolenium salt IV which decomposes into β‐chloroethyl formate (V) and antimon pentachloride (VI) (Eq. (2)) or acts as initiator by reacting with 1,3‐dioxolan (Eq. (3)). Triphenylmethyl tetrachloroantimonate does not initiate polymerization of 1,3‐dioxolan but forms exclusively β‐chloroethyl formate. SbCl5, formed according to Eq. (2), reacts with 1,3‐dioxolan to produce again the dioxolenium salt IV together with HCl and non‐initiating by‐products: SbCl3 and (CH3OCH2CH2O)n SbCl5hyphen;n, in proportions depending on the reaction conditions.β‐Chloroethyl formate has been found to be present in the polymerization mixture at concentrations close to those calculated on the assumption that the reaction between the original initiator (I, IV, VI, triethyloxonium hexachloroantimonate or triphenylmethyl tetrachloroantimonate) and 1,3‐dioxolan as well as the further decomposition of IV go to completion.All the initiators (In) give the same polymerization rates which are proportional to [In]0 in toluene solution and proportional to [In]20 in dichloromethane solution.Considering the competitive consumption of the initiator and the formation of the true initiating species these results can be rationalized by the analysis of the kinetics according to the reaction scheme.Polymerization has been found to be of first order in monomer and to proceed without an induction period. Thus, initiation is fast, in agreement with the previously measured rates of hydride transfer to the triphenylmethyl cation and the fast decomposition of the dioxolenium salt in the presence of 1,3‐dioxolan.
Zur copolymerisation von α‐methylstyrol und butadien. II. Das NMR‐spektrum der sequenzen mit zentraler butadieneinheit
Authors: Elgert K. F. , Seiler E. , Puschendorf G. , Cantow H.‐J. 
Published: April 2003

AbstractDie 220‐MHz‐Protonenresonanzspektren von Copolymeren aus α‐Methylstyrol und Butadien wurden untersucht. Die Modellsubstanzen wurden in einer durch Lithiumbutyl initiierten Polyreaktion bei ‐75°C in Tetrahydrofuran hergestellt. Unter diesen Bedingungen wird das Butadien bevorzugt in 1,2‐Stellung verknüpft. Bei der Analyse des NMR‐Spektrums der seitenständigen Vinylgruppe wurde keine Aufspaltung durch Sequenzen unterschiedlicher Taktizität gefunden. Durch Verwendung von 2,3‐Dideuterobutadien gelingt die Deutung des Spektrums im Resonanzbereich der Methin‐ und Methylen‐Protonen durch Triaden und Pentaden mit zentraler Butadieneinheit. Die gemessenen Partialkonzentrationen stimmen mit den aus der Copolymerisationsgleichnng berechneten gut überein. Der Grad der 1,4‐Verknüpfung des Butadiens ist nicht konstant, sondern hängt von der α‐Methylstyrolkonzentration in der Ausgangsmischung ab.
Vibrational spectra of some new deuterated polypropyleness
Authors: Wolfsgruber C. , Cabassi F. , Tosi C. 
Published: April 2003

AbstractThe IR spectra of six atactic and five isotactic deuterated polypropylenes are reported. The vibrational assignment is discussed based on a careful mutual comparison of the spectra in addition to a comparison with those already known from the literature.
Studies of the polymerization of diallyl compounds. XVI. Copolymerizations of diallyl esters of aromatic dicarboxylic acids with methylallyl benzoate
Authors: Matsumoto Akira , Sasaki Hiromi , Oiwa Masayoshi 
Published: April 2003

AbstractRadical copolymerizations of diallyl phthalate (DAP), diallyl isophthalate (DAI), and diallyl terephthalate (DAT) with methylallyl benzoate (MABz) have been carried out in bulk at 60°C, using benzoyl peroxide as initiator.In the copolymerization of DAP with MABz the residual unsaturation of the copolymer decreased with increasing mole fraction of MABz in the feed. In the case of DAI it was nearly constant, regardless of the molar feed ratio, whereas with DAT it tended to increase with increasing mole fraction of MABz in the feed. These results were interpreted by considering the difference of the mode of cyclization in the case of DAP, DAI, and DAT.The following monomer reactivity ratios γ1 (of the uncyclized radical), γc (of the cyclized radical) and γ2 (of the MABz radical) were estimated on the basis of the cyclocopolymerization mechanism. DAP: 0,84; 0,61; 1,08; DAI: 0,76; 0,52; 1,06. For the copolymerization of DAT with MABz the apparent monomer reactivity ratios based on the general copolymer composition equation were obtained as γ1 = 0,79 and γ2 = 1,06.
Vernetzte polymere mit spaltbaren netzbrücken. II. kinetik der vernetzenden copolymerisation
Authors: Braun Dietrich , Brendlein Wolfgang 
Published: April 2003

AbstractBei der Copolymerisation von Diolefinen mit Monoolefinen entstehen im allgemeinen vernetzte Polymere. In der vorliegenden Arbeit wird die Kinetik derartiger Copolymerisationen beschrieben. Es wird ein numerisches Rechenverfahren angegeben, das die Zahl der Vernetzungsstellen in Abhängigkeit vom Umsatz und von den Copolymerisationsparametern liefert. Die Ergebnisse werden anhand einiger Beispiele erläutert.
Fractionation of cellulose acetate by thin‐layer chromatography
Authors: Kamide Kenji , Manabe Sei‐Ichi , Osafune Etsuko 
Published: April 2003

AbstractAn attempt is made to evaluate the distribution of acetyle content (ACD) and of molecular weight distribution (MWD) of cellulose acetate by means of thin‐layer chromatography (TLC). A binary mixture of methylene chloride (MC)/methanol is useful for ACD evaluation, and ternary mixtures of MC/tetrahydrofuran (THF)/methanol and MC/acetone/methanol are suitable for evaluating MWD. The step‐wise composition method is powerful in eliminating a tailing effect as well as to improve the separation efficiency. For MC/THF (or acetone)/methanol (or butanol) a series of ridges is observed in the diagram of rate of flow (Rf)‐composition of the mixture. This can be explained reasonably in terms of variation of polarity of the mixture together with variation of solubility of the polymer in the mixture. Separation with respect to the acetyl content or molecular weight is due to the two different mechanisms: an adsorption‐desorption mechnism and a phase‐separation mechanism. Which plays the predominant role for a given TLC experiment depends on the mixture composition and the developing conditions i. e., mixtures having a methanol content less than 5–10% are mainly controlled by the adsorption‐desorption mechanism and mixtures with a methanol content higher than 50–60% by the phase‐separation mechanism.
The origin of the initiating activity of (C2H5)3O+PF for the polymerization of N‐vinylcarbazole
Authors: Turchi Gino , Matera Felice , Magagnini Piero L. 
Published: April 2003

AbstractIn the presence of (C2H5)3O+PF (1) N‐Vinyl carbazole (NVC) can polymerize rapidly and completely especially in methylene dichloride. A study of this polymerization, with 14C‐labelled (C2H5)3O+PF and with living polytetrahydrofuran as apparent initiators, has shown that oxonium ions are not responsible for the initiation. The true initiator is most probably PF5 formed by the decomposition of the salt. The necessary co‐initiator is provided by an impurity in the monomer. The initiation by a solution of living poly‐THF, containing PF−6 ions, is explained by the formation of traces of PF5 in a termination reaction of the THF polymerization.
Thermal analysis of poly(1,3,4‐oxadiazole‐2,5‐diyl‐1,4‐phenylene) and poly 1,3‐phenylene‐1,3,4‐oxadiazole‐2,5‐diyl‐1,4‐phenylene
Authors: Varma I. K. , Sambandam R. M. , Varma D. S. 
Published: April 2003

AbstractPoly(1,3,4‐oxadiazole‐2,5‐diyl‐1,4‐phenylene) (I) and poly(1,3‐phenylene‐1,3,4‐oxadiazole‐2,5‐diyl‐1,4‐phenylene) (II) and its nitroderivative have been prepared by condensation polymerization using fuming H2SO4and different quantities of terephthalic acid (TA), isophthalic acid (IA), nitrophthalic acid (NA), and hydrazine sulphate (HS) respectively. Homopolymers of TA and HS, and copolymers of TA, IA, HS and TA, NA, and HS of different intrinsic viscosities were prepared by varying the reaction conditions. The polymer structures were investigated by visible range spectra, UV spectra, IR spectra and elemental analysis. The existence of poly(1,3,4‐oxadiazolediyl‐phenylene)‐ and poly(hydrazoterephthaloyl)‐structures was revealed by these studies. These polymers were thermally stable and most of them did not show any loss in weight below 360°C. The maximum weight loss was in the temperature range of 460–480°C. The activation energyEand the frequency factorAfor the thermal degradation were evaluated. Linear relationships betweenEand the intrinsic viscosity and between the “integral procedural decomposition temperature” and the intrinsic viscosity were observed. The polymers I showed a higher stability than the copolymers II of similar molecular weights.
Vinyl polymerization by metal complexes, 10. Initiation by polyvinylamine–copper (II) chelate
Authors: Inaki Yoshiaki , Kimura Keiichi , Takemoto Kiichi 
Published: April 2003

AbstractThe polymerization of acrylonitrile, methyl methacrylate and styrene initiated by copper(II) chelates was studied in the prescence of carbon tetrachloride. A polymeric amine and a monomeric diamine, that is, polyvinylamine and 1,3‐diaminopropane, were chosen as ligands. The activity of the polymeric chelate was found to be specific and higher than that of the 1,3‐diaminopropane chelate. It was compared with that of the 1,3‐diaminopropane chelate, by changing pH values of the system and the reaction temperature. Plots of conversion against pH afforded a peak at pH 8, and trends of increasing of conversion were observed above pH 10. The apparent activation energy of the polymerization initiated by the polymeric chelate was higher than the apparent activation energy of the polymerization initiated by the 1,3‐diaminopropane chelate. The fact was attributed to the difference of their chemical structures.