bluuebunny/crossref_metadata_2025_split huggingface dataset:
The dependence of excimer formation of polystyrene solutions on solvent and concentration
Authors: Nishihara Toshio , Kaneko Motozo 
Published: April 2003

AbstractThe fluorescence spectra of polystyrene solutions have been measured in various solvents. The ratio of the intensity ID of the excimer (short living excited dimer) band to the intensity IM of the monomer band depends on the solvent. The values extrapolated to diluted solutions may be related to the average density of segments in a polymer molecule. Above concentrations of 0.1 g/100 ml, the ratio ID/IM increases with increasing concentration, and the peak position of the excimer band shifts to a longer wavelength.
On the persulphate‐bisulphite‐Cu2+ initiated emulsion polymerization of vinyl chloride. Kinetics and mechanism in the presence of a complexing agent
Authors: Mørk P. C. , Ugelstad J. 
Published: April 2003

AbstractThe persulphate‐bisulphite‐Cu2⊕ initiated emulsion polymerization of vinyl chloride has been investigated in the presence of a metal‐ion complexing agent (trisodiumcitrate). In the range of concentrations investigated, the rate of radical production from the redox system was found to be 2nd order with respect to the concentration of NaHSO3 and independent of the persulphate concentration. The effect of the concentrations of citrate and copper ions was found to be strongly dependent on the ratio [citrate]t/[Cu]t (index t indicating total added amounts). In borax and phosphate buffer, the rate of polymerization was found to be proportional to [Cu]t1/4·[citrate]−1/2 at ratios larger than about ten. When the ratio approaches unity, an abrupt increase in rate was observed. A kinetic scheme based on the equilibrium reaction

is discussed. The effects of [Cu]t and [citrate]t, as predicted by this scheme, were calculated by computing numerical values of [Cu2⊕] according to the above equilibrium. This proved the theory to be in good agreement with the experimental results.
The use of matrices for a complete description of copolymers
Authors: Tosi Camillo , Allegra Giuseppe 
Published: April 2003

AbstractMathematical formalisms based on the application of matrix techniques were lately applied to multicomponent copolymerizations; they led to expressions giving the fractional distribution of each monomer present in a linear copolymer of a certain degree of polymerization.In this paper an extension of these treatments, which allows us to describe in a conceptually simple way of the whole sequence distribution of copolymers.
The crystal structure of isotactic polyepichlorohydrin
Authors: Perego G. , Cesari M. 
Published: April 2003

AbstractThe crystal structure of poly(chloromethyl ethylene oxide) or polyepichlorohydrin has been carried out, by X‐ray diffraction technique. The parameters of the orthorhombic unit‐cell are:a= 12.16 Å,b= 4.90 Å,c= 7.03 Å, fairly coincident with those given by RICHARDS (Diss. Abstr.22(1961) 1029). Two space‐groups are proposed: Pna21and Pnam, the former being more probable. Chain conformation is exactly like that previously given by the authors for the poly‐propylene‐oxide. The side chloromethyl‐group lies on a plane perpendicular to the chain axis, in accordance with the staggered bonds principle.
Effect of unsaturated hydrocarbons on the polymerization of butadiene with nickel catalyst
Authors: Sakata Ryozo , Hosono Junichi , Onishi Akira , Ueda Kenichi 
Published: April 2003

AbstractEffect of various aliphatic hydrocarbons on the cis‐1.4 polymerization of butadiene with nickel naphthenate/boron trifluoride etherate/triethylaluminum catalyst was investigated. It was observed that vinylcyclohexene, allenes, and acetylenes retarded the initiation and the propagation and enhanced the chain transfer. The retarding effect is stronger in the order: paraffin, monoolefin < vinylcyclohexene ≦ acetylene < allene = butadiene‐1.2 < methylacetylene < vinylacetylene. The microstructure of the polymer is not affected by the presence of these compounds. The retarding effect was discussed in terms of the coordination of the unsaturated hydrocarbons to the catalyst.
Plastic deformation of polypropylene. V. Annealing of drawn polypropylene
Authors: Baltá‐Calleja F. J. , Peterlin A. 
Published: April 2003

AbstractIsotactic polypropylene samples drawn at 20 and 100°C to a draw ratio 6 and 10 were annealed with free and fixed ends between 40 and 155°C for periods of time between 1 and 103 min. All the annealing effects proceeded farther with unclamped samples free to shrink than with clamped samples. The disorientation of crystal lattice and the shrinkage are extremely fast reaching saturation values characteristic for the temperature of annealing. At higher annealing temperature, one could observe merely the saturation values with the whole transition being completed in less than 1 min. The long period growth, the increase in density, and the intensity of small‐angle X‐ray scattering are linear functions of the logarithm of annealing time and hence persist with gradually decreasing rate long after the completion of disorientation and shrinkage. The observed effects can be well explained on the basis of the two‐stage model of plastic deformation of crystalline polymers which assumes the formation of strong well‐aligned microfibrils connected by interfibrillar tie molecules.
The kinetics of the thermal decomposition of the peroxodisulphate ion in aqueous solutions of various cationic surface‐active agents
Authors: Crematy Edward P. 
Published: April 2003

AbstractA study has been undertaken of the kinetics of the thermal decomposition of potassium peroxodisulphate in aqueous solutions of n‐butyltrimethyl‐, n‐butyltriethyl‐, and n‐octyltriethylammonium chlorides. It has been found that the rate of disappearance of the peroxodisulphate ion is markedly increased in the presence of the cationic surfactants. Experiments with allyl acetate (a free‐radical scavenger) show that there is no direct reaction between peroxodisulfate and surfactant, and that the increased rate of disappearance of the peroxide is due to a free‐radical induced decomposition.The rate law has been elucidated, rate coefficients and activation parameters computed, and free‐radical mechanistic sequence discussed.
Topochemical reactions of monomers with conjugated triple‐bonds. IV. Polymerization of bis‐(p‐toluene sulfonate) of 2.4‐hexadiin‐1.6‐diol
Authors: Wegner Gerhard 
Published: April 2003

AbstractSolid‐state polymerization of the bis‐(p‐toluene sulfonate) of 2.4‐hexadiin‐1.6‐diol was achieved by UV‐irradiation or by annealing the monomer crystals below their melting‐point. Deep red polymer crystals having the original shape of the monomer crystals exhibiting strong dichroism are obtained. Polymerization proceeds by 1.4‐addition to the conjugated triple‐bonds to form a polymer with three cumulated double bonds per baseunit and a fully conjugated backbone. Photopolymerization is rather fast and does not show an induction period. The relationship between ηsp/c‐values and conversion as well as X‐ray work indicates that the formation of nuclei must be an important feature of the reaction mechanism. Thermal (spontaneous) polymerization shows a considerable induction period and very high viscosity‐values are obtained for thermal polymers.
Kinetik der Polymerisationsauslösung mit aromatischen pinakolen
Authors: Braun Dietrich , Becker Knut H. 
Published: April 2003

AbstractVinylmonomere lassen sich durch aromatische Pinakole oberhalb von 40°C radikalisch polymerisieren. Die Polymerisationsauslösung erfolgt durch eine Wasserstoffübertragung der primär durch thermischen Zerfall der Pinakole gebildeten Diarylhydroxymethyl‐Radikale auf die Monomermoleküle. Hieraus ergibt sich theoretisch eine Proportionalität zwischen Polymerisationsgeschwindigkeit vBr und Initiatorkonzentration [I]1/2 sowie Monomerkonzentration [M]3/2; dieses Geschwindigkeitsgesetz kann experimentell bestätigt werden. Es wird aus kinetischen Untersuchungen geschlossen, daß die Wasserstoffübertragung in einem Übergangszustand erfolgt, der aus einem Monomermolekül und einem Initiatorradikal gebildet wurde.
Solvent effects in radical copolymerization III. Methacrylamide
Authors: Saini Guido , Leoni Alvaro , Franco Simone 
Published: April 2003

AbstractThe free radical copolymerization of methacrylamide with styrene and methyl methacrylate has been investigated at 70°C in solvents having different dielectric constants. A strong influence of the solvent on the copolymerization parameters has been observed. Such behaviour is quite similar to that found by the same authors for acrylamide copolymerization and differs completely from that found for N.N‐dialkyl acrylamide. The influence of the solvent properties (polarity, dielectric constant etc.) on the amide‐enol equilibrium is discussed.
The configuration of cellulose dissolved in iron‐sodiumtartrate
Authors: Valtasaari Lea 
Published: April 2003

AbstractViscosity and light scattering data on 10 cellulose samples in the iron‐sodiumtartrate solvent (FeTNa) are presented and examined in the light of the FLORY‐FOX treatment of dilute solution properties. The FLORY factor, Φ, is found to increase with mol. wt. approaching a constant value when M̄w exceeds 500 000. Good linear correlation with the data is found for [η] M̄w as a function of R. Functions proposed for evaluation of the unperturbed dimensions by means of intrinsic viscosity and mol. wt. have been tested on the present data. Good linear fit is obtained for six of these from medium to high molecular weight range. From the slope of the linear part of the STOCKMAYER‐FIXMAN plot, the second virial coefficient is calculated, according to KRIGBAUM, which is in good agreement with the experimental values obtained by light scattering. It is suggested that a decrease of flexibility with decreasing mol. wt. could result from immobilization of monomer‐monomer bonds in the cellulose‐iron complex formed on dissolution.
Vinyl polymerization initiated by the dimethylaniline N‐oxide/tosyl chloride system
Authors: Sato Tsuneyuki , Yoshioka Minoru , Otsu Takayuki 
Published: April 2003

AbstractA study of the vinyl polymerization initiated by the system dimethylaniline N‐oxide (DMAO) in conjunction with tosyl chloride (TsCl) has been performed. According to the kinetic results of the polymerization of methyl methacrylate (MMA) and of the copolymerization of MMA with styrene, the polymerization proceeds via a radical mechanism. The rate of polymerization is given by the following equation:

equation image

and the overall activation energy was calculated to be 14.3 kcal · mole−1. According to the UV spectrum, the poly‐MMA obtained probably contains N‐methylanilinomethyl end groups.A graft polymer was obtained by polymerization of MMA with DMAO and partially chlorosulfonated polyethylene (Hypalon‐30). From the results an initiation mechanism is proposed and discussed.
Equilibrium ring‐opening polymerization of mono‐ and multicyclic unsaturated monomers
Authors: Ofstead Eilert A. , Calderon Nissim 
Published: April 2003

AbstractEquilibrium ring‐opening polymerization theory has been extended to cycloolefin polymerizations. Previous work had established the reversible nature of the olefin metathesis reaction, the basic process whereby cycloolefins undergo ring‐opening. The present work confirms the reversible character of cycloolefin polymerization for the cases of cyclopentene and bicyclo[4.3.0]nona‐3.7‐diene polymerization. Equilibrium conversion data for cyclopentene polymerizations have provided estimates of the enthalpy (−4.4 kcal/mole) and entropy (−14.9 cal/mole·deg) of polymerization. In addition, some factors governing the polymerizability of mono‐ and multicyclic monomers are discussed.
Topochemical polymerization of monomers with conjugated triple bonds
Authors: Wegner G. 
Published: April 2003

AbstractSolid‐state polymerization of monomers with conjugated triple bonds turns out to be a versatile method for synthesis of crystalline polymers of high molecular weight exhibiting a fully conjugated backbone. The reaction is best described as an 1.4‐addition polymerization of the conjugated triple bonds giving rise to a polymer with three cumulated double bonds per repeating unit. The all‐trans configuration of the substituents is a consequence of the solid‐state reaction mechanism and is already predetermined by the packing of the molecules in the monomer lattice. It was shown by X‐ray analysis in the case of poly(2.4‐hexadiin‐1.6‐diol‐bis‐phenylurethane) that the polymer diacetylenes can be described by either a butatriene structure or by a mesomeric en‐in‐structure.
magnified image
Polymerization of the colorless monomer crystals is achieved by irradiation with UV‐ or high‐energy radiation or by simply annealing the monomer crystals below their melting point. Deep red, blue or black polymer crystals are obtained exhibiting strong dichroism with the fibre axis as the direction of main absorption. These crystals possess semiconducting properties (EA = 0.6–1.0 eV, depending on the substituents at the conjugated backbone).
Phase equilibrium of the cellulose derivatives determined by differential thermal analysis. 1. Methylcellulose/water
Authors: Kagemoto Akihiro , Baba Yoshihiro , Fujishiro Ryoichi 
Published: April 2003

AbstractA DTA apparatus suïtable for measuring polymer solutions has been constructed. By using this apparatus the phase equilibrium of the system methylcellulose/water was studied. The precipitation temperature was determined from the DTA curve which shows a sigmoidal shape. The thermodynamic parameters for entropy Ψ1 = 2.11 and enthalpy, χ1 = 2.13 (at 328.8°K) and the theta temperature, Θ = 59.5°C were estimated.
New completely aliphatic anionic membranes from polymers of unsaturated tertiary amines. Part I. Preparation and properties
Authors: Credali Lino , Chiolle Antonio , Parrini Paolo 
Published: April 2003

AbstractNew anionic membranes of completely aliphatic structure have been prepared starting from homopolymers and copolymers of unsaturated aliphatic tertiary amines.These membranes have an exchange capacity ranging from 0.5 to 4.0 meq/g dry substance and a permoselectivity exceeding 90%.Using reversible Ag/AgCl electrodes, the membrane potential for these membranes has been measured in various NaCl solutions, in order to determine the transport number. Moreover, the membrane conductivity has been determined as function of the concentration of the electrolyte in the external solution.These membranes, since they do not contain the arylalkyl‐trimethylammonium group, offer greater resistance to alkaline conditions than conventional ones.
Plastic deformation of nylon 6 single crystals and thin membranes
Authors: Sakaoku K. , Peterlin A. 
Published: April 2003

AbstractThe deformation of single crystals shows two preferential directions for crack formation at 60° to each other. The cracks open very little on crystals lying directly on the Mylar substrate and substantially more on the higher layers of a multilayer crystal. The primary crack direction is parallel to the plane of hydrogen bridges. The microfibrils bridging the cracks are too short for a good dark field electron micrograph. Deformed thin membranes occasionally show a lamellar structure. After annealing at 215°C well oriented single crystal blocks belonging to microfibrils can be observed.
Polymere aus Nitrilen. I. Anionische Polymerisation von Bernsteinsäuredinitril
Authors: Wöhrle D. 
Published: April 2003

AbstractBernsteinsäuredinitril wurde in Gegenwart von anionisch angreifenden Katalysatoren zu Polymeren umgesetzt. Die Polymerisation des Nitrils z. B. mit Natriummethylat in Methanol führt zum Poly(1‐pyrrolin‐2‐yl‐5‐ylidennitrilo), welches Halbleitereigenschaften mit σ300°K ∼ 10−8Ω−1cm−1 aufweist. Bei der Umsetzung von Bernsteinsäuredinitril mit Kalium‐tert‐butylat in Substanz erhält man dagegen Poly[(4‐amino‐2.5.6‐pyrimidintriyl)‐2.6‐dimethylen], welches Isolatoreigenschaften hat. Die Ergebnisse der thermischen Analysen werden mitgeteilt.
A novel method of determination of reactivity ratios in binary and ternary copolymerizations
Authors: Jaacks Volker 
Published: April 2003

AbstractThe determination of reactivity ratios is simplified by using an excess of one monomer (M1) at a time large enough that the copolymers will have a very small content of the other monomer (M2). In this case chain propagation takes place almost exclusively by addition to polymer radicals with a terminal M1‐unit (P) and monomer consumption by propagation of P may be neglected. One reactivity ratio (r1) is obtained from monomer conversions by means of a simple integrated equation which is valid up to high conversions. A calculation is proposed in order to account for the neglected propagation via P. The other reactivity ratio (r2) is obtained from copolymerizations with excess M2.As the new method uses an integrated form of the MAYO equation it permits the determination of monomer conversions directly by gas chromatography of unreacted monomers. Thus, if desired, analysis of copolymers can be avoided. The gas chromatographic method has been tested with the radical copolymerization of styrene and methyl methacrylate.In ternary and quaternary copolymerizations the new method offers particular advantages.
Radikalbildung und Kettenbruch bei der Radiolyse von Polypropylensulfid
Authors: Raven A. V. , Hesse P. , Heusinger H. 
Published: April 2003

AbstractDie Radiolyse von Polypropylensulfid mit Mercapto‐ und Thioätherendgruppen wurde untersucht. Die Ergebnisse der Molekulargewichtsveränderung mit der Dosis ergeben, daß statistischer Kettenbruch auftritt (GBruch = 0,4–0,7). Folgende Radikale konnten ESR‐spektroskopisch identifiziert werden:
magnified image
Es wird ein Mechanismus aufgezeigt, der die Radikalbildung mit dem Kettenbruch in Zusammenhang bringt. Hieraus geht hervor, daßB bevorzugt Spaltung von CC und nicht von CS‐Bindungen stattfindet.
Untersuchungen über den einfluß der ladungsdichte auf die gegenseitige desaktivierung von polyion‐makroradikalen
Authors: Görlich Werner , Schnabel Wolfram 
Published: April 2003

AbstractMittelständige Makroradikale R• wurden in wäßriger Lösung bei Raumtemperatur durch H‐Abstraktion (•OH + RH → H2O + R•) aus folgenden Polymeren erzeugt: Polyvinylalkohol (PVA), partiell mit Glyoxylsäure acetalisierter PVA, Copolymere aus Vinylpyrrolidon/Acrylsäure und Vinylalkohol/Acrylsäure. Die biomolekulare Geschwindigkeitskonstante kR der Reaktion R• + R• wurde mit der Methode der Pulsradiolyse gemessen. Im Falle des PVA ist kR im Polymerisationsgradbereich 2·103 bis 2·104 unabhängig vom Polymerisationsgrad der Makroradikale. Im Falle von Polyelektrolyten mit Kettenlängen zwischen 4·103 und 2·104 ergab sich folgendes: Beträgt der Gehalt xi an ionisierten Grundbausteinen weniger als 0,5 Mol‐%, so steigt kR mit zunehmendem xi an (maximal um den Faktor 4). Diese Zunahme wird auf die Knäuelexpansion zurückgeführt, die eine Folge der intramolekularen COULOMBschen Abstoßung ist. Im Bereich xi > 0,5 Mol‐% kommt die intermolekulare Abstoßung voll zur Wirkung, und kR fällt um etwa drei Größenordnungen ab.
Essais d'interprétation du gonflement à l'équilibre de réticulats‐modèle préparés par voie anionique
Authors: Haeringer Arnaud , Hild Gerard , Rempp Paul , Benoit Henri 
Published: April 2003

AbstractUne série homologue de gels de polystyrène a été préparée par voie anionique dans des conditions standard. Seule varie d'un échantillon à l'autre la masse moléculaire des éléments linéaires compris entre deux noeuds successifs. La fonctionnalité de ces derniers n'est pas accessible à l'expérience. Le taux de gonflement à l'équilibre de ces gels a été étudié et il a été établi que le modèle du gel gaussien idéal, décrit par DUSEK et PRINS peut leur ětre appliqué, moyennant quelques hypothèses concernant l'état de relaxation et le paramètre d'interaction avec le solvant. La fonctionnalité des noeuds est de l'ordre de 4, pour cette série de gels.
Photo‐sensitized polymerization of styrene under high pressure
Authors: Ogo Yoshiaki , Yokawa Masaru , Imoto Tatsuya 
Published: April 2003

AbstractThe polymerization of styrene, photosensitized by azocyclohexane‐1,1′‐dinitrile, was studied at 30°C over a pressure range of 1 to ca. 1000 bar. The average lifetimes of the growing polymer chains were determined by the rotating‐sector method. By measuring the effect of pressure on the individual reactions of styrene polymerization, the activation volumes for the propagation and the termination were obtained as −17,9 cm3/mol and 13,1 cm3/mol, respectively. The overall activation volume was also measured as −17,9 cm3/mol and was nearly equal to that calculated from the individual activation volumes (−17,8 cm3/mol). The propagation rate constant increases exponentially with pressure, whereas the termination rate constant decreases rapidly up to 500 bar and then decreases slowly as the pressure increases further.
Über mehrparameterkorrelationen der kationischen polymerisation von vinylmonomeren: Einfluß des katalysatorsystems
Authors: Heublein Günther , Dawczynski Horst 
Published: April 2003

AbstractFür die kationische Polymerisationp‐substituierter Styrole wurden unter Standardbe‐+gungen die Einflüsse der Lewiskatalysatoren sowie der Cokatalysatoren auf die Bruttopolymerisationsgeschwindigkeit (kBrutto) und den Durchschnittspolymerisationsgrad (DP) der erhaltenen Polymeren untersucht. Als Parameter wurden Leitfähigkeitswerte (χKat.) sowie Glaselektrodenpotentiale (εGlas/Kat.) neu eingeführt. Ihre Korrelation mit logkBruttobzw. logDPliefert lineare Abhängigkeiten.
The grüneisen constant of polymers
Authors: Warfield R. W. 
Published: April 2003

AbstractA method based on the pressure dependence of the bulk modulus was developed for determnining the Lattice Grüneisen Constant, γL, of polymers. This technique was applied to a series of polymers and the results indicated that γL for most polymers lies between 4 and 9. These results were discussed in terms of the anharmonic properties of polymers and, in particular, in terms of the interchain specific heat.
Infrared spectroscopic studies of polymer transitions, 4. A second‐order transition of cellulose triacetate in the vicinity of 30°C
Authors: Ogura Katsuyuki , Miyachi Yuko , Sobue Hiroshi , Nakamura Shigeo 
Published: April 2003

AbstractA second‐order transition of cellulose triacetate at approximately 30°C was studied by polarized infrared spectroscopy. The temperature dependences of infrared dichroismus were examined for the 900cm−1 (C1H bending vibration) and 600 cm −1 (acetyl group frequency) bands. The former changed at about 30°C, whereas the latter did not show any remarkable change. These results suggest that the transition observed here is probably related to the conformational change of the pyranose ring. The transition mechanism is supposed to be associated with the chair (C 1)‐boat (B) transformation of the pyranose ring at the folding of the cellulose molecule.
Sequenzspezifische Cooligokondensation von Nucleinsäure‐Bausteinen mit Affinitäts‐Schutzgruppen, 2. Cooligomere von 5′‐O‐[p‐Anisyldiphenylmethyl]thymidin und Desoxynucleotiden
Authors: Seliger Hartmut , Schütz Helmut , Philipp Manfred 
Published: April 2003

AbstractDie Cooligokondensation von 5′‐O‐[p‐Anisyldiphenylmethyl]thymidin mit Thymidylsäure und Derivaten der Desoxycytidylsäure und Desoxyguanylsäure wurde untersucht. Die Cooligomeren MMTrdT(pdN)n (N = Nucleosid) wurden von den Homooligomeren und nicht umgesetztem Nucleotid durch Chromatographie auf einer Tritylcellulose‐Säule abgesondert und anschließend auf einer Diäthylaminoäthylcellulose‐Säule nach Kettenlänge getrennt. Im bestuntersuchten Beispiel, der Cooligokondensation mit N‐Isobutyryl‐desoxyguanosin‐5′‐phosphat, wurde die Nucleosidkomponente vollständig in Cooligomere eingebaut: die Ketten der Länge 2, 3, 4 und 5 wurden in 77‐, 18‐, 3‐ und 2proz. Ausbeute erhalten. Die erzielbare mittlere Kettenlänge kann u. a. durch Variation der Schutzgruppen und des Komponentenverhältnisses beeinflußt werden.