bluuebunny/crossref_metadata_2025_split huggingface dataset:
Poly‐(α‐methyl benzyl methacrylate). Preparation and preliminary observations
Authors: Liu Kang‐Jen , Lignowski J. S. , Ullman Robert 
Published: April 2003

AbstractPoly‐(α‐methyl benzyl methacrylate) (PMBMA) polymers were prepared in isotactic, syndiotactic, and atactic forms using both optically active and racemic monomers. The isotactic material was prepared by anionic polymerization in a hydrocarbon solvent at a low temperature (∼−60°C), the syndiotactic and atactic polymers were synthesized by ultraviolet initiated free radical polymerization at –65 and 32°C, respectively. From the proton magnetic resonance spectrum, it could be determined that the isotactic polymer was of high stereochemical purity. The syndiotactic material was less pure, and the atactic polymer was largely syndiotactic. Racemic and optically active α‐methyl benzyl pivalates were prepared to serve as monomeric analogues of the polymer. The optical activity of the isotactic polymer in dioxane is one‐third greater than that of the monomeric analogue at 5890 Å; the syndiotactic polymer is slightly less optically active than the monomeric analogue, and the atactic polymer is between the syndio‐ and iso‐polymers but much nearer the syndio material. The enhancement or decrease of the optical activity is associated with the orientation correlation of successive chain segments, the specific chemical structure of the optically active group, and on solvent‐polymer interactions. The orientation correlations persist over a short range only.
Über die synthese und das redoxverhalten molekular‐einheitlicher hydrochinon‐phenol‐formaldehyd‐konden‐sate. IV
Authors: Manecke Von G. , Mölleken R. 
Published: April 2003

AbstractEs wird die Darstellung niedermolekularer, molekulareinheitlicher Hydrochinon‐Phenol‐Formaldehyd‐Kondensate beschrieben. Die aromatischen Bausteine sind über Methylenbrücken ausschließlich in 2.5‐Stellung verknüpft. Das Redoxverhalten dieser als Modellsubstanzen für Redoxharze dienenden Verbindungen wurde durch potentiometrische Titration untersucht.
Multimerisation: Assoziation und aggregation von makromolekülen. V. Assoziation „ataktischer”︁ polypropylene
Authors: Elias Von Hans‐Georg , Dietschy Hansjörg 
Published: April 2003

AbstractDas Lösungsverhalten von Polypropylenen unterschiedlicher Konfiguration und verschiedenen Molekulargewichtes wurde untersucht. Die hochmolekularen isotaktischen Polypropylene zeigen zeitabhängige Aggregation. Die niedermolekularen, ätherlöslichen Fraktionen wiesen Konzentrationen an isotaktischen Triaden zwischen 0 und 73% auf. Sie erwiesen sich in allen untersuchten Lösungsmitteln (Benzol, Toluol, Cyclohexan, Methylcyclohexan, Brombenzol, Tetrachlorkohlenstoff und Trichloräthylen) nach dampfdruckosmotischen Messungen als assoziiert. Die Gleichgewichtskonstanten der Assoziation lagen zwischen 20 und 82000 l. mol−1. Die Messungen in Brombenzol folgten der VAN'T HOFFschen Gleichung nicht. Aus den thermodynamischen Daten wurde auf einen Desolvatationsprozeß als treibende Kraft für die Assoziation geschlossen. Die Assoziationskonstanten nehmen mit steigender Konzentration an isotaktischen Triaden ab.
Graft copolymerization of methyl methacrylate onto cellulose
Authors: Namasivaya D. , Patnaik B. K. , Thampy R. T. 
Published: April 2003

AbstractMethyl methacrylate has been grafted onto cellulose pulp using manganic ion as the initiator. The variable parameters studied are initiator and monomer concentrations, temperature and reaction time. The grafting efficiency, degree of grafting and frequency of grafting are found to be dependent on the above mentioned variables.
Polymerization of methyl methacrylate initiated by 3.3.4.4‐tetraphenyl hexane and 1.1.2.2‐tetraphenyl cyclopentane
Authors: Borsig E. , Lazár M. , Čapla M. 
Published: April 2003

AbstractThe kinetics of polymerization initiated by mono‐ and biradicals formed by decomposition of 3.3.4.4‐tetraphenyl hexane (TPH) resp. 1.1.2.2‐tetraphenyl cyclopentane (TPCP) have been investigated. The results point to a larger participation of the biradicals from TPCP in the termination reactions than of the monoradicals with TPH. It has been further established that with both above mentioned initiators the usual rate increase in consequence of the gel effect does not occur. On the other hand, in both cases a considerable growth of the average molecular weights takes place in the course of polymerization.
Über probleme der kationischen polymerisation des caprolactams. I. Die polymerisation mit caprolactam‐hydrochlorid
Authors: Doubravszky Von Sándor , Geleji Frigyes 
Published: April 2003

AbstractWir untersuchten die Caprolactampolymerisation mit Caprolactam‐hydrochlorid mit Hilfe der dilatometrischen Methode. Auf Grund des Zusammenhangs zwischen Geschwindigkeitsmaximum und Katalysatoranfangskonzentration sollten beide funktionelle Gruppen der bei der Initiierungsreaktion entstandenen Produkte am Kettenwachstum teilnehmen. Nach dem Maximalwert zu Reaktionsbeginn sinkt die Polymerisationsgeschwindigkeit bis zu einem Minimum und wächst dann wieder bis zum Erreichen eines stationären Wertes. Der Gesamtcharakter der kinetischen Kurven deutet darauf hin, daß der Polymerisationsmechanismus verwickelt ist und sich wahrscheinlich das Kettenwachstum nicht auf dem Wege ein und desselben Elementarschrittes abspielt.
A theoretical interpretation of the BUECHE‐HARDING master curve
Authors: Conti W. , Gigli I. 
Published: April 2003

AbstractThe extension of the BUECHE theory to heterogeneous polymers is performed by assuming that (a) the maximum relaxation time of the fractions is proportional to the 4.5 power of the molecular weight and (b) the same mixing rule for the fractions is valid at every shear rate. For bulk polymers the Mn and Mw mixing rules are considered. For values of η/η0 ≥ 0.2 and 3 ≥ Mw/Mn ≥ 1.2 the flow curves of the heterogeneous polymers may be expressed by means of the following equation:

where the δ and K values are dependent on the heterogeneity ratio Mw/Mn, the mixing rule, and the type of molecular weight distribution. (erfc = complementary function to error function).The BUECHE‐HARDING standard curve is very close to an erfc function and by comparing it with our theory it can be proved that the BUECHE‐HARDING curve is the flow curve of a polymer with Mw/Mn = 1.20. Consequently we have MR = Mw or MR = 0.58 Mw whether the Mw or Mn mixing rule is considered.Experimental data is compared with the theoretical results and this comparison is discussed.
Étude de la cristallisation des polyèmres. III. Détermination de la température de fusion et cinétique de fusion isotherme des polyoxyéthylènes de faible masse moléculaire
Authors: Spegt Par P. A. , Terrisse J. , Gilg B. , Skoulios A. 
Published: April 2003

AbstractOn décrit dans ce travail une étude dilatométrique de la fusion isotherme de polyoxyéthylénes de faible masse moléculaire. On a interprété les données expérimentales en supposant que seule la vitesse d'évacuation de la chaleur gouverne la cinétique de fusion.On a déterminé la temipérature de fusion des polyoxyéthylénes en fonction de la masse moléculaire et on en a déduit le rapport de l'énergie de surface et de l'enthalpie de fusion.
Monodisperse polymers by anionic polymerization
Authors: Guzmán G. M. , Bello A. 
Published: April 2003

AbstractNearly monodisperse styrene and methyl methacrylate polymers of high molecular weight have been prepared by anionic polymerization at low temperatures. A. single‐stage vapour addition method has been used to mix the catalyst and monomer. Styrene was polymerized by Na‐biphenyl in tetrahydrofuran, and methyl methacrylate by Li‐biphernyl in dimethoxyethane as the solvent. The poly(methyl methacrylate) was syndiotactic. Deviations from ideal monodispersity and the appearance of bimodal distributions have been interpreted in terms of two kinds of active centers during polymerization: ion‐pairs and free anions. A quantitative estimate of both kinds has been carried out.
Über substituierte polystyrol‐phenyl‐disulfimide
Authors: Koch Von Ursula , Wolf Friedrich , Skilandat Peter 
Published: April 2003

AbstractEs wurden Polystyrol‐phenyl‐disulfimide hergestellt, die im Phenylkern durch Methyl‐Chlor‐ oder Carboxylgruppen substituiert waren. Die Bestimmung der thermischen Beständigkeit ergab keine Verbesserung gegenüber dem unsubstituierten Polymeren.
Bemerkung zur molekulargewichtsbestimmung nach TRAUTMAN
Authors: Sutter Von W. , Burchard W. 
Published: April 2003

AbstractAn verschiedenen Systemen werden Messungen mit Hilfe des TRAUTMAN‐Verfahrens vorgenommen und die Ergebnisse mit denen von Sedimentationsgleichgewichts‐ und Sedimentationsgeschwindigkeitsmessungen verglichen. Während die Ergebnisse der YPHANTIS‐ und Sedimentationsgeschwindigkeitsmethode gut übereinstimmen, ergeben sich nach dem TRAUTMAN‐Verfahren große Unterschiede sowohl im Molekulargewicht als auch in der Konzentrationsabhängigkeit des scheinbaren Molekulargewichts.
Cyclopolycondensations. IV. Investigation of the polymerization mechanism of aromatic diaminodicarboxylic acid in polyphosphoric acid and the thermal stability of aromatic polyamide amino acids
Authors: Kurihara Masaru , Yoda Naoya 
Published: April 2003

AbstractIn order to elucidate the reaction mechanism of the polyphosphoric acid solution Polymerzation of aromatic diaminodicarboxylic acid, a model reaction with anthranilic acid in Polyphosphoric acid was studied. It was established that the polymerization procceds via the formation of phosphorylated reaction intermediates followed by self‐polycondensation to form high molecular weight aromatic polyamides containing benzoxazinone rings along the polymer main chain. The effect of additives such as benzidine and naphthalene was studied, and the mechanism of polymerization is discussed based on the elementary analyses and on infrared spectral and proton magnetic resonance spectral data. Furthermore, the thermal stability of aromatic polyamides was determined by thermogravimetric and differential thermal analyses, and the crystallinity of the polymer was measured by X‐ray diffraction.
The mechanism of dispersion of starch by urea and by guanidinium and lithium salts
Authors: Erlander Stig R. , Tobin R. 
Published: April 2003

AbstractThe ability of various aqueous salt solutions to disperse high‐amylose corn starch (70 % apparent amylose) was examined. The results were interpreted in light of a proposed theory concerning the structure and properties of hydrated ions and molecules. In those solutions where both cation and anion have negative hydration (possess only B‐regions) such as guanidinium thiocyanate, the solubility of starch continues to increase to the saturation point of the salt. On the other hand, if the cation has positive while the anion has negative hydration, then the solubility of starch goes through a maximum (at 6 M LiBr or 6 M LiSCN). It is proposed that only the negatively hydrated domains of a salt disperse starch. The negatively hydrated domains of an anion or cation disperse starch granules in one of two ways. If the effective dielectric constant of the ion is greater than that of water, then the dispersion occurs by swamping out the electrostatic forces involved in a hydrogen bond. If the effective dielectric constant of the negatively hydrated ion is less than that of water, then the ion can disperse starch granules only when it becomes unhydrated as in the case of 9 M LiCl. In other words, dispersion occurs by hydrating the hydroxyl groups to the ions. Such electrostatic interactions may be involved in some proteinpolysaccharide complexes.
Polymerisation von Lactonen 7. Mitt.: Polymerisation von β‐trichlormethyl‐β‐lactonen
Authors: Ohse Von Helmut , Cherdron Harald 
Published: April 2003

AbstractEs wurde die Polymerisierbarkeit folgender, nunmehr leicht zugänglicher, β‐Lactone untersucht: β‐Trichlormethyl‐β‐propiolacton (TCPL), β.β‐Bis(trichlormethyl)‐β‐propiolacton (HCPL) und α.α‐Dimethyl‐β‐trichlormethyl‐β‐propiolacton (DMTCPL). Lediglich von TCPL und DMTCPL konnten Polymere erhalten werden, und zwar nur mit kationischen Initiatoren. HCPL dagegen polymerisierte unter den gleichen Bedingungen nicht.
Sur le mécanisme du gonflement des hauts polymères cristallins par les solvants
Authors: Descamps‐Carlier J. , Homès G. A. , Point J. J. 
Published: April 2003

AbstractSpecimens of polyethylene laminated at room temperature and annealed at 110°C were swelled at 85°C by biphenyl and then quickly allowed to cool to room temperature.X‐ray diffraction studies at large and low angles revealed that during the cooling process, biphenyl crystallizes into flat crystals of about 10 Å thickness, located between the polyethylene single crystals. The swelled specimens are friable. It is possible to desaggregate them into single crystals as shown by electron diffraction. Swelling does not affect the texture of the initial polyethylene specimens which is that of a b̄ axis fibre. Further more during the cooling process the orientation taken by the biphenyl crystals depends only on the polyethylene texture. The texture of biphenyl is that of a b̄ axis fibre parallel to the polyethylene fibre.
Condensation polymerization of N‐dithiocarbonyl alkoxyearbonyl amino acids. Part V. Studies on reaction mechanism
Authors: Kato H. , Higashimura T. , Okamura S. 
Published: April 2003

AbstractN‐Dithiocarbonyl ethoxycarbonyl amino acids (DTE‐amino acids) (I) are easily converted to high molecular polypeptides by heating in dioxane. To elucidate the reaction mechanism, the formation of by‐products or intermediates in the polymerization of DTE‐glycine and ‐alanine were studied. Thiazolid‐2.5‐dione (IV) and 2‐thio‐oxazolid‐ 5 ‐one (III) were isolated as by‐products. (III) is unstable and changes to polypeptide and (IV). The IR‐absorption of a isothiocyanate group is observed keeping (I) and (III) in KBr disks at room temperature and in the initial stage of the polymerization of (I). These results suggest the following predominant mechanism for the formation of poly‐peptides proceeding via the isothiocyanate carboxylic acid (II):
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Osmometry with membrane‐permeating solutes of low molecular weight
Authors: Coll H. 
Published: April 2003

AbstractExperimental osmotic pressure (p)‐time (t) curves for several low‐molecular weight Solutes in toluene were studied by means of a recording automatic osmometer. The results for a monodisperse solute can be expressed by p = r π exp (−αt), with π the theoretical osmotic pressure. In the case of more than one solute the pressures are additive. for a given set of experimental conditions, the parameters r and α depend on the molecular weight of the solute, but to some extent also on its structure. It is shown how an approximate estimate of molecular weight and concentration of a polymer additive can be made from p versus t plots in the course of a molecular weight determination of the polymer.The results could not be brought in agreement with the equation of HOFFMANN and UNBEHEND. Also, the assumptions underlying the theory of LAIDLER and SHULER do not seem to be adequate in the general case to relate α to r.
Mechanical relaxation in poly(2.6‐dimethyl‐1.4‐phenylene oxide) in the glassy state
Authors: de Petris S. , Frosini V. , Butta E. , Baccaredda M. 
Published: April 2003

AbstractDynamic mechanical properties (sound velocity, v, and damping factor, Q−1) have been determined in poly(2.6‐dimethyl‐1.4‐phenylene oxide) over a wide range of temperature (from 80 to 500°K) at acoustic frequencies.The examined polymer exhibits two mechanical relaxation effects, one, α, at temperatures above 480°K, characterized by a sudden strong drop of the elastic modulus and by a rapid increase of the damping factor with increasing temperature, and another, β, below the glass transition point, Tg, characterized by a small drop of the elastic modulus, between 290 and 370°K, and by a damping maximum at about 370K (fm = frequency corresponding to the maximum ⋍ 7000 Hz).The α relaxation effect has been attributed to the thermal excitation of cooperative motions in the chain, while the secondary β relaxation has been interpreted as due to oscillation of aromatic rings around COC bond. The damping maximum, for the lateer, is shifted toward higher temperatures with increasing frequency, following an ARRHENIUS‐type equation with an apparent activation energy of about 20 kcal/mole.
On the polymerization and copolymerization of sulfolenes
Authors: Goethals E. J. 
Published: April 2003

Abstract3‐Sulfolene is not polymerizable at temperatures below 80°C with radical or ionic catalysts. At 100°C or higher and in the presence of AIBN polybutadienesulfone is formed. Attempts to copolymerize 3‐sulfolene with various vinyl compounds were unsuccessful. Likewise 2‐sulfolene is not polymerizable; but it was possible to copolymerize it with acrylonitrile or vinyl acetate. The reactivity ratios were found to be: r (vinyl acetate) = 1.52 ± 0.12; r (2‐sulfolene) = 0.0 ± 0.1. A transfer mechanism with 2‐sulfolene is discussed.
Studies on polymers from cyclic dienes. VII.. Cationic polymerization of methylcyclopentadiene
Authors: Aso Chuji , Ohara Osamu 
Published: April 2003

AbstractPolymerization of methylcyclopentadiene was carried out with FRIEDEL‐CRAFTS catalysts. The monomer contained 1‐methyl and 2‐methyl isomers only. No isomerization of the monomer occurred during polymerization. All the polymers obtained were soluble in organic solvents such as toluene. The rate of polymerization and the intrinsic viscosity of the polymer decreased with increasing concentration of 1‐methylcyclopentadiene in the monomer feed. The structure of the polymer was determined by NMR spectroscopy and it was shown that most of the 1‐methylcyclopentadiene units were incorporated as the 3.4‐structure, 70 to 95% of the 2‐methylcyclopentadiene units as the 1.4‐structure and the residual part as the 3.4‐structure. The ratios of the 1.4‐ and 3.4‐structures of the 2‐methylcyclopentadiene units changed with polymerization conditions but not with monomer composition.
Über den einbau von chlor bei der polymerisation von methacrylsäuremethylester XV. Mitteil. Polymerisationen und polymerisationsinitiatoren
Authors: Bredereck Von Hellmut , Franz Raimund , Krämer Botho 
Published: April 2003

AbstractBei der Polymerisation von Methacrylsäuremethylester in Gegenwart von methyleneaktiven Initiatoren sowie Chlorid und Luftsauerstoff wird Chlor in das Polymere eingebaut. Der Einbau wurde radiochemisch bestimmit. Der in Gegenwart von α‐Benzoyl‐propionitril gefundene, von der Chlorid‐Konzentration abhängige Chlor‐Einbau wird durch einen durch Chlorid bewirkten Zerfall des intermediär gebildeten Hydroperoxids gedeutet. In Gegenwart von N‐Äthyl‐bis‐(p‐toluolsulfonylmethyl)‐amin bzw. 1.3.5‐Trimethyl‐barbitursäure ist der Chlor‐Einbau von der Chlorid‐Konzentration unabhängig. Es wird ein bevorzugt thermischer Zerfall des intermediären Hydroperoxids angenommen.
Gemische von polymeren durch cofällung, III. Mitt. Untersuchung der binären polymersysteme: Polyacrylnitril/acetylcellulose, polyvinylacetat/acetylcellulose und polyvinylacetat/polyacrylnitril
Authors: Vasile Von Cornelia , Sandru Florica , Schneider I. A. , Asandei N. 
Published: April 2003

AbstractDie Änderung der Aktivierungsenergie des thermischen Abbaues von Polymergemischen mit ihrer Zusammensetzung kann zu wertvollen Hinweisen auf die Verträglichkeit oder Unverträglichkeit von Homopolymeren führen. Durch Messung dieser Aktivierungsenergie können sowohl geringe Abweichungen von der Additivitätsregel hervorgehoben und Bereiche maximaler Verträglichkeit abgegrenzt, als auch die thermische Stabilität der gebildeten Pseudolösungen im Vergleich zu den entsprechenden Homopolymeren vorausgesagt werden.Beim Mischen von pseudoverträglichen Polymeren sind im allgemeinen zwei entgegengesetzte Tendenzen zu beobachten: (a) ein Anwachsen der Aktivierungsenergie infolge von Assoziatbildung und somit ein Anstieg der Thermostabilität, (b) ein Abfall der Aktivierungsenergie infolge Bildung fester Lösungen mit Eutektikum, die durch eine geringere thermische Stabilität charakterisiert sind.So bestehen bei AcC/PAN‐Cofällungsgemischen negative Abweichungen der Aktivierungsenergie, wobei sich für das Eutektikum ein Wert von ΔE = −14,8 kcal/Mol ergibt. Tatsächlich sinken die Anfangszersetzungstemperaturen der Cofällungsgemische bis zu 25°C unter die entsprechenden Temperaturen bei den Homopolymeren. Dagegen weisen PAN/PVA‐Cofällungsgemische positive Abweichungen auf, wobei sich für ein 1:1‐Gemisch ein Wert von ΔE = 12,3 kcal/Mol ergibt; entsprechend liegt die Anfangszersetzungstemperatur um 15°C höher als die der Homopolymeren.Bei AcC/PVA‐Gemischen sind keine Abweichungen von der Additivität zu beobachten, was auf das Fehlen von Wechselwirkungskräften hindeutet und somit für Unverträglichkeit dieser Polymergemische spricht.Es wird versucht, eine strukturelle Erklärung für die beobachteten Erscheinungen zu geben.
Vinyl polymerization 177. Polymerization of acrylonitrile initiated with the imidazole — carbon tetrachloride system
Authors: Imoto Minoru , Takemoto Kiichi , Otsuki Takeki , Ueda Nasuo , Tahara Seiichiro , Azuma Heiichi 
Published: April 2003

AbstractAcrylonitrile, methyl methacrylate, styrene, methyl acrylate, acrylic acid, and methacrylic acid were found to be polymerized by the system of imidazole and carbon tetrachloride. The polymerization proceeded through radical mechanism. In spite of the presence of carbon tetrachloride, the molecular weight of the polymer obtained was very high. The polymer contained chlorine, and from the reaction product Cl− could be extracted by water. From these results and the data of NMR measurements, an initiation mechanism was proposed. Also some polymers of N‐vinyl compounds, such as poly‐4‐vinylpyridine or poly‐2‐ethyl‐N‐vinylimidazole, were found to be active. However, the initiation mechanism seemed to differ from that by the above imidazole‐carbon tetrachloride system.In the polymerization initiated by imidazole and carbon tetrachloride, various macromolecules, such as cellulose, poly‐N‐vinylpyrrolidone or poly‐N‐vinylcarbazol, could accelerate the polymerization of acrylonitrile. A matrix mechanism is still in question for this interesting reaction.
A rapid method for the determination of Θ‐conditions of polymer solutions
Authors: Talamini G. , Vidotto G. 
Published: April 2003

AbstractA method for the rapid determination of the Θ‐conditions of polymer solutions is proposed. According to this method the Θ‐conditions are determined by using an equation, obtained theoretically, which relates the temperature (for binary systems) or composition (for ternary systems) for incipient phase separation, to the molecular weight of the polymer.The values of the Θ‐conditions obtained using this method are in very good agreement with that determined by other methods.
Copolymerization of vinyl and cyclic monomers in the solid state
Authors: Herz J. H. , Stannett V. , Turner D. T. 
Published: April 2003

AbstractA study has been made of the polymeric product obtained by exposure to γ‐rays of carefully dried eutectic mixtures of styrene and β‐propiolactone which were sealed in vacuum and maintained at a few degrees below the melting point. No copolymer was formed, only a mixture of homopolymers. However, evidence was obtained which supports an earlier claim that a copolymer is formed by γ‐irradiation of a solid mixture of acrylonitrile and β‐propiolac tone.
The polymerization of acrylamide initiated with ceric ion in the presence of ferric ion
Authors: Narita Hiroshi , Okamoto Susumu , Machida Seishi 
Published: April 2003

AbstractIn the presence of ferric ion, polymerization of acrylamide initiated with ceric ion was studied. The resulting polyacrylamide was found to contain cerium and iron, and the total metal content of the polymer corresponded to one atom per macromolecule. Experimental data of paper electrophoresis, polarography and IR spectroscopy suggested that the metals combined chemically with the polymer molecule. A probable mechanism of introduction of the metal into the polymer chain is discussed.