bluuebunny/crossref_metadata_2025_split huggingface dataset:
Isotactic poly‐pentene‐1: Polymorphism and some physical properties
Authors: Danusso F. , Gianotti G. 
Published: April 2003

AbstractPreliminary results of a physical study of highly isotactic poly‐pentene‐1 are here reported.This polymer, although crystallizable to a high degree, can be fractionated by a normal fractional precipitation technique. This is due to its capacity of giving metastable solutions in bad solvents, and therefore a liquid‐liquid separation, owing probably to its relatively low crystallization rate. Fractions were thus prepared for further experiments.Isotactic poly‐pentene‐1 is found to be able to crystallize into two modifications: modification 2, so far known, having melting temperature at 80°C.; and the apparently more stable modification 1, with a melting temperature regularly affected by molecular weight, but exceptionally dependent on crystallization temperature. Its maximum melting temperature is estimated, although in a non definite way to be around 130°C.X‐rays diffraction diagram and volumetric and dilatometric data of the two pure modifications are given.The volume‐temperature relationship of the amorphous isotactic phase is eventually drawn from experimental data and three dilatometric isophasic transitions are individualized at −52°, −10° and +13°C.
Experimentelle prüfung der beziehungen zwischen mechanischen konstanten von gelen für dehnung bei konstantem quellungsgrade einerseits, bei konstantem partialdruck des quellungsmittels andererseits
Authors: Kuhn Von W. , Müller S. , Kuhn H. J. , Eisenberg A. 
Published: April 2003

AbstractZwei verschiedene Bedingungen, unter denen eine gequollene Folie elastisch verformt werden kann, sind: 1. Dehnung bei konstanter Zusammensetzung, insbesondere bei konstantem Gehalt des Gelfadens an Quellungsmittel und 2. Streckung bei konstantem Partialdruck des Quellungsmittels. Die Elastizitätsmodule E, E′ und die POISSONschen Zahlen μ, μ′ für diese beiden Dehnungsbedingungen werden definiert und experimentell festgestellt. Eine quantitative beziehung zwischen diesen vier Größen, die in einer früheren Arbeit hergeleitet worden war, konnte experimentell bestätigt werden.
Über die synthese linearer polyester mit OH‐gruppen als kettenständige seitengruppen. 21. Mitt. über polyester
Authors: Batzer Von Hans , Mangold Hugo 
Published: April 2003

AbstractEs werden Versuche beschrieben zur Herstellung eines Polyesters mit OH‐Gruppen an der Molekülkette durch polymeranaloge Hydrierung eines Polyesters aus einer Keto‐dicarbonsäure und einem Diol.
Beitrag zur deutung des infrarotspektrums von nylon 6,6
Authors: Heidemann Von Gerhard , Zahn Helmut 
Published: April 2003

AbstractDurch Grenzflächenpolykondensation wurde aus Hexamethylendiamin‐1,1,6,6,N,N′‐D8 bzw. Adipinsäuredichlorid‐2,2,5,5‐D4 Nylon 6,6 hergestellt, das in α‐Stellung zur Amidgruppe spezifisch auf der Amin‐ oder Säureseite (N‐vicinal und CO‐vicinal) deuteriert ist. Mit Hilfe der Infrarotspektren der aus diesen Proben hergestellten Filme können eindeutig folgende relativ starke Banden des Nylon 6,6‐Spektrums zugeordnet werden:Deformationsschwingung der N‐vicinalen CH2‐Gruppe bei 1474/cm, Deformationsschwingung der CO‐vicinalen CH2‐Gruppe bei 1416/cm, Twistingschwingung der CO‐vicinalen CH2‐Gruppe bei 1198/cm und Twistingschwingung der N‐vicinalen CH2‐Gruppe bei 1179/cm.Die Lage der Deformationsschwingungsbanden dieser Gruppen ist von der Konformation zur Amidgruppe abhängig. Bei Verdrehung aus der idealen trans‐Anordnung fallen δCH2(N) und δCH2(CO) bei 1435/cm zusammen.Die Unterschieden in den Bandenlagen und ‐intensitäten sowie deren Abhängigkeit von der Konformation lassen sich qualitativ erklären. Hieraus ergibt sich die Forderung nach einer intramolekularen Wechselwirkung zwischen CH‐Gruppen auf der Amin‐Seite sekundärer Amid‐Gruppen und deren π‐Elektronensystem.
Model structures for vinyl polymers. I. Polyacrylonitrile
Authors: Clark Howard G. 
Published: April 2003

AbstractA model dimer of acrylonitrile (2,4 dimethylglutaronitrile) was synthesized and separated into an isotactic (meso) isomer, m.p. −8.8°C., and a syndiotactic (racemic) isomer, m.p. =50°C. Infrared and NMR spectra of the dimers were measured. The methylene protons of the isotactic dimer resonate at a lower magnetic field strength and show a more complex spin‐spin splitting than the syndiotactic methylene protons.
A new catalyst system for the polymerization of epoxides
Authors: Kambara Shu , Takahashi Akio 
Published: April 2003

AbstractVarious epoxides such as ethylene oxide, propylene oxide, epichlorohydrin, isobutylene oxide, 2‐chloromethyl propylene oxide, styrene oxide, and phenylglycidyl ether, can be polymerized to high molecular weight, crystalline polymers with catalyst systems of AlEt3/transition‐metal chelate compound.Poly(propylene oxide) having an intrinsic viscosity up to 11 was obtained by AlEt3/bis(dimethylglyoximo)nickel(II). Crystalline poly(epichlorohydrin), poly(styrene oxide), poly(phenylglycidyl ether) with high molecular weights were formed. The last polymer is insoluble in common solvents at room temperature and can be converted to a strong fiber and a tough film.In addition, the polymerization mechanism by a coordinate propagation process is discussed.
Rate constant of propagation reaction in stationary state of cationic polymerization. Part V1. Copolymerization
Authors: Kanoh N. , Gotoh A. , Higashimura T. , Okamura S. 
Published: April 2003

AbstractIn order to determine the relationship between the relative reactivity of a monomer and that of its propagating species the propagation rate constant of cationic copolymerization was measured. The relative reactivity of the monomer was found in the following order:

for styrene derivative p‐methoxystyrene > p‐methylstyrene > styrene > p‐chlorostyrene; for alkyl vinyl ether: isobutyl vinyl ether > 2‐chloroethyl vinyl ether.
On the other hand, the order of the relative reactivity of the propagating species ending in the styrene derivative and the alkyl vinyl ether was as follows:

for styrene derivative: p‐methoxystyrene > p‐methylstyrene > styrene > p‐chlorostyrene; for alkyl vinyl ether: 2‐chloroethyl vinyl ether > isobutyl vinyl ether.
Preparation of poly(p‐aminostyrene) via the schmidt rearrangement of poly(p‐acetylstyrene)
Authors: Van Paesschen G. 
Published: April 2003

AbstractPoly(p‐aminostyrene) can be prepared by acid hydrolysis of poly(p‐acetaminostyrene), which is obtained in good yield by a SCHMIDT rearrangement of poly(p‐acetylstyrene).The structure of the obtained products has been confirmed by infrared spectra, microanalysis, and organic analysis.
Über die Reaktion von Glykolen mit der olefinischen Doppelbindung bei der Darstellung von ungesättigten Polyestern durch Schmelzkondensation
Authors: Ordelt Von Zdenek 
Published: April 2003

AbstractBei der Polykondensation des Maleinsäureanhydrids bzw. der Malein‐ oder Fumarsäure mit Äthylenglykol wurde dessen Anlagerung an die Doppelbindung des ungesättigten Dicarbonsäurebausteins und die Bildung von 1‐(2‐Hydroxyäthoxy)‐äthan‐1,2‐dicarbonsäure bzw. deren Ester nachgewiesen. Die Anlagerung ist nicht nur auf alkylsubstituierte 1,2‐Glykole beschränkt, wie von KNÖDLER, FUNKE und HAMANN7 mitgeteilt wurde. Die Anlagerung des Glykols hängt vor allem von der Reaktionstemperatur, der Konzentration der Hydroxylgruppen und der Stärke der im Reaktionssystem anwesenden Säuren ab. Der kationoide Mechanismus der diskutierten Anlagerung läßt annehmen, daß es sich um eine allgemeingültige Umsetzung zwischen Alkoholen und α,β‐ungesättigten Carbonsäuren bzw. deren Estern handelt, die der anionoiden Anlagerung im alkalischen Medium entspricht. Die Anlagerung von Glykolen erklärt Abweichungen vom linearen Aufbau ungesättigter Polyester und die damit im Zusammenhang stehenden Abweichungen ihrer Eigenschaften.
Kinetische Untersuchungen zur alkalischen Umsetzung von o‐Kresol mit Formaldehyd. Zur Phenolharzbildung, 2. Mitt.1
Authors: Schiemann Von Günther , Hartmann Edzard 
Published: April 2003

AbstractMit Hilfe der Papierchromatographie, die in der 1. Mitt. zur quantitativen Bestimmung der in Frage kommenden Verbindungen ausgearbeitet wurde, wird die Kinetik der Umsetzung von o‐Kresol mit Formaldehyd in verdünnter alkalischer Lösung bei 35°C verfolgt. Die Reaktionsgeschwindigkeitskonstanten der Formaldehydanlagerung werden bestimmt. Auch die Stabilität der einzelnen sich bildenden Verbindungen, d.h. besonders einkerniger o‐Kresol‐methylolverbindungen, ihre Abspaltung von Formaldehyd sowie ihre Kondensationsreaktionen werden dabei untersucht.
Anionische Oligomere von Methacrylsäuremethylester. 2. Mitt. Die alkalische Verseifung der Oligomers
Authors: Schreyer Von G. , Völker Th. 
Published: April 2003

AbstractAnionisch hergestellte Oligomere des Methacrylsäuremethylesters verseifen in methanolischer bzw. äthanolischer Kalilauge in der Weise, daß die an den endständigen, tertiären Kohlenstoffatomen gebundenen Estergruppen unabhängig vom Polymerisationsgrad mit konstanter und hoher Geschwindigkeit k1 verseifen. Von den restlichen, an quartären C‐Atomen gebundenen Estergruppen verseift lediglich nur eine mit noch meßbarer Geschwindigkeit k2; k1 und k2 unterscheiden sich etwa um eine Größenordnung.
The thermal degradation of poly(methyl vinyl ketone) and its copolymers with acrylonitrile
Authors: Grassie N. , Hay J. N. 
Published: April 2003

AbstractIt was confirmed that the thermal degradation of poly(methyl vinyl ketone) is a random reaction in which water is liberated from pairs of adjacent units resulting in conjugated sequences of limited length. When methyl vinyl ketone units are incorporated into polyacrylonitrile molecules by copolymerization the rate of thermal colouration is greater than in pure polyacrylonitrile, the rate of elimination of water is greater than from pure poly(methyl vinyl ketone) and the extensive colouration which occurs in polyacrylonitrile is maintained in the copolymer. These features of the thermal degradation of the copolymer are explained in terms of a series of reactions of a similar type to the propagation process of the chain reaction responsible for the colouration of polyacrylonitrile. In support of this it has been shown that by the use of appropriate initiators a chain reaction can be made to occur in poly(methyl vinyl ketone) which results in elimination of water and the production of extensive conjugated sequences.
Two‐stage polymerization of styrene in tetrahydrofuran with Na‐naphthalene
Authors: Wenger Franz 
Published: April 2003

AbstractA two stage process for the anionic polymerization of styrene in THF is described. Initiation by Na‐naphthalene is carried out at room temperature with a small amount of styrene, adding the rest of the monomer by slow distillation at −78°C. The present technique yields relatively homogeneous product of predictable molecular weight. The agreement between measured molecular weights and the ones calculated from the polymerization mechanism by the relation M̄nk = 2M/[Ī] is within 10%. From fractionation, M̄w/M̄n ratios are determined to be < 1.1 for all samples.
Dipole moments and molecular structure of copolymers. II. Dipole moment of methyl acrylate‐styrene copolymers
Authors: Shima Mikiko , Kotera Akira 
Published: April 2003

AbstractThe dielectric properties of methyl acrylatestyrene copolymers in benzene solution were measured, and it was found that the value of dipole moment, μ, of methyl acrylate monomer unit in the copolymers increased with an increase of styrene content, e.g. from 1.46 D (for polymethyl acrylate) to 1.61 D (for the copolymer of which mole fraction of methyl acrylate is 0.23) at 20°C. The theoretical treatment described in the preceding paper has been applied to the experimental results and the variation in values of μ is discussed from a consideration of the detailed arrangement of polar monomer units in the copolymer molecule.
Das papierchromatographische verhalten zweier homologer reihen phenolischer mehrkernverbindungen mit novolakstruktur
Authors: Kämmerer Von Hermann , Mofachami Schapur , Göbel Ingrid 
Published: April 2003

AbstractEs gelang, Mehrkernverbindungen, die aus über Methylenbrücken verbundenen p‐Kresolbausteinen bestehen, bis zur Siebenkernverbindung papierchromatographisch zu trennen. Die RF‐Werte hängen in regelmäßiger Weise vom Molekulargewicht ab. Darüber hinaus deuten sich Zusammenhänge zwischen Struktur und RF‐Wert an.
Infrared studies on organometallic compounds as polymerization catalysts. I. Diethylzinc‐alcohol system for epoxide polymerization
Authors: Ishimori Michihiro , Tsuruta Teiji 
Published: April 2003

AbstractInfrared spectra of Et2Zn‐alcohol system were measured in a liquid cell with KBr or NaCl windows. The reaction of diethylzinc with alcohol proceeds according to the equations:
magnified imageReaction 1 takes place rapidly, whereas reaction 2 proceeds very slowly. The active species in the polymerization of propylene oxide was confirmed to be zinc dialkoxide in situ. The nature of alcohol and the reaction temperature are important factors in the catalyst activity.
Kristallinität und schmelzbereiche von isotaktischen polystyrolen. VI. Mitt. Über die stereospezifische polymerisation mit alkaliorganischen verbindungen
Authors: Braun Von Dietrich , Hintz Hans , Kern Werner 
Published: April 2003

AbstractEs werden nach verschiedenen Methoden Kristallisationsversuche an isotaktischen Polystyrolen unterschiedlichen Molekulargewichts durchgeführt. Gemische von isotaktischen und ataktischen Polystyrolen werden mit verschiedenen Kristallisationsmedien behandelt und die abgetrennten kristallisierten isotaktischen Anteile durch RÖNTGENdiagramme und Schmelzpunkte charakterisiert.Einige durch Polymerisation von Styrol mit n‐Amylnatrium hergestellte Polystyrole werden nach der Fällungsmethode fraktioniert. Die Verteilung der Polymerisationsgrade ist sehr breit. Die hochmolekularen Polystyrolfraktionen sind durchweg gut kristallisierbar und weisen relativ hohe Taktizität auf, während sehr niedermolekulare Fraktionen aus ataktischen Polystyrolen bestehen. Im mittleren Molekulargewichtsbereich (10 000–20 000) liegen mit großer Wahrscheinlichkeit Mischungen aus ataktischen und isotaktischen Polystyrolen vor, die mit den bekannten Methoden nicht getrennt werden können.
Interfacial polymerization for the preparation of regularly alternating polyesteramides
Authors: Williams J. L. R. , Carlson J. M. , Reynolds G. A. 
Published: April 2003

AbstractPolyesteramides have been prepared by interfacial condensation of hexamethylene glycol‐1,6‐bis(4‐chlorocarbonylbenzoate) and various alkylenediamines. The melting points of these polyesteramides are compared with samples prepared previously by melt condensation of bisesteramides and glycols.
Ultracentrifugal extrapolated molecular weights of polyelectrolytes
Authors: Erlander Stig R. 
Published: April 2003

AbstractThe extrapolated ultracentrifugal molecular weight for a polyelectrolyte in a polar solvent is shown to be equal to Mext = MP—ZPMB where MP is the true molecular weight of the polyelectrolyte, ZP is its electrostatic charge, and MB is the molecular weight of a low molecular weight electrolyte. This relationship is shown to be true for a polyelectrolyte in the absence or presence of added salt. Hence, the relationship Mext = MP/(1 + ZP) is never obtained for a polyelectrolyte for equilibrium ultracentrifugation in a polar solvent.
Maxima of degree of polymerization in equilibrium systems
Authors: Eisenberg Adi 
Published: April 2003

AbstractPlots of the degree of polymerization vs. temperature may show maxima in systems polymerizing under equilibrium conditions. It is shown that an equation correlating the temperature at which the maximum occurs with the thermodynamic constants of the polymerizing system, which was previously developed for the autoinitiated polymerization of sulfur can also be applied to the most general case of polymerization subject to external initiation. It is pointed out that such maxima are to be expected when the enthalpies of initiation and propagation are positive, and when the former greatly exceeds the latter.
Non‐NEWTONIAN flow of dilute ethyl acetate solutions of high molecular weight cellulose nitrate studied by capillary viscosimetry
Authors: Lohmander Ulv , Svensson Åke 
Published: April 2003

AbstractThe gradient dependence of viscosity has been studied for five fractions of cellulose nitrate (around 13.7% N) in the molecular weight region 0.36–5.5·106. The velocity gradient range covered is 0.5 to 150,000 sec−1. The slope of the ηsp/c vs. concentration curves decreases with increasing gradient but more rapidly for higher molecular weights. The gradient at which this slope becomes zero increases with decreasing molecular weight. For all fractions it was easy to extrapolate the [η] vs. shear rate curves with simple, equilateral hyperbolas. [η]∞ may be considered to be proportional to [η]0 according to the relation [η]∞ = 0.13 [η]0. The experimental results are viewed in the light of various theories based on anisotropy of hydrodynamic interaction, rigidity of the macromolecular coil, and nonuniform expansion of the macromolecular coil.
A determination of the concentration and temperature dependence of the refractive index increment of polydimethylsiloxane in toluene
Authors: Nilsson Rune , Sundelöf Lars‐Olof 
Published: April 2003

AbstractRefractive index increments were determined very accurately for polydimethylsiloxane in toluene for the wavelengths 436 and 546 mß at five different temperatures from 15° to 35°C. Solutions of concentrations ranging from 0.005 to 0.05 g./ml. were used. the temperature and concentration dependence of the increment was obtained. The observed values are compared with those calculated from a Gladstone and Dale expression and the agreement is found to be very good.
Über die polymerisation von acrylnitril mit silbernitrat
Authors: Schnecko Von H. W. 
Published: April 2003

AbstractDie Polymerisation von Acrylnitril mit AgNO3 in Substanz und in Lösung wird untersucht. In orientierenden Kinetischen Versuchen wird gefunden, daß die Reaktion nach einem radikalischen Mechanismus abläuft; sie wird durch Licht katalysiert. Außerdem wird die Aktivität einer Reihe anorganischer Salze und organischer Nitratebei der Initiierung der Polymerisation geprüft. Die Reaktionsmöglichkeiten werden diskutiert.
The kinetics of the polyurethane‐forming reaction between organic diisocyanates and glycols. II
Authors: Okada Hisao , Iwakura Yoshio 
Published: April 2003

AbstractWith the object of clarifying the kinetics of addition reaction between organic isocyanates and alcohols, the rate of reaction between phenyl isocyanate and 1‐butanol in benzene was examined in the presence of butyl phenylurethan, butyl butylurethan, and tributylamine at 20, 30, and 40°C. by the method of differential calculi on the graph of conversion against reaction time, and the effect of these added compounds on the reaction has been investigated. The mechanism and the rate equation for the reaction of organic isocyanates with alcohols, which had been studied by Baker et al.2 and Sato7, were re‐examined and discussed.
Heats of polymeric reactions. III. Methacrylic, acrylic, and vinyl esters, and some alternating copolymerization systems
Authors: Joshi R. M. 
Published: April 2003

AbstractHeats of polymerization of several methacrylic, acrylic and vinyl esters were measured on an isothermal distillation calorimeter working at 74.5°C. Size and other structural variations in the ester group of methacrylic esters appear to have small but distinct effect on the energies of the bonds involved in polymerization and hence on the heat of polymerization. The esters in the other two series are less susceptible to such influence. In methacrylic esters the increase in ester length caused a progressive increase in the slope of the (linear) plots of initial rates of polymerization vs. (initiator)1/2, which may be attributed to the shielding effect of the ester group on the propagating free radical, affecting termination more than the propagation.In the alternating copolymerization systems the average heat of cross propagation was found to be considerably higher than the average of the two heats of self addition, accounting for the essentially 1:1‐molar composition of the copolymer and the high rates of copolymerization.
A light scattering study on hydroxyethyl cellulose in binary mixtures of water‐dimethyl sulphoxide and water‐formamide
Authors: Friedberg F. , Brown W. , Henley D. , Öhman J. 
Published: April 2003

AbstractStudies have been made on hydroxyethylcellulose in binary mixtures of water/dimethylsulphoxide and water‐formamide. Light scattering and viscosity measurements were made in the mixture ranges 0–100% dimethyl sulphoxide Me2SO and 0–80% formamide (vol.‐%).For both solvent systems, somewhat anomalous results were obtained. Water and dimethyl sulphoxide are both solvents for hydroxyethyl cellulose. However, light scattering and viscosity results reveal polymer aggregation in the mixtures containing 30–75% dimethyl sulphoxide. This behaviour is a consequence of strong dipole‐dipole interactions between water and dimethyl sulphoxide, leading to a solvent structure that greatly diminishes interactions with the polymer. Formamide is a non‐solvent (at 25°C.) for hydroxyethyl cellulose, although water‐formamide mixtures ( < 80% formamide) are thermodynamically good solvents. Light scattering data show uniformily high coil extensions in this range, and also that the solvent environment of the polymer is that of the bulk solvent. Such behaviour is interpreted by the associated structure of pure formamide, which is substantially altered by the presence of water.
Dimerisation and trimerisation of 2,4 tolylene di‐isocyanate
Authors: Davis A. 
Published: April 2003

Abstract2,4 tolylene di‐isocyanate can form a dimer (TDID) and a trimer (TDIT). For bulk polymerisation at temperatures in the range 40°C. to 100°C. the initial rates of these processes are given by the expressions,

equation image
At each temperature the rate of trimerisation remained essentially constant over the conversion range examined, but the rate of dimerisation decreased gradually to zero. The equilibrium concentrations of TDID at 78°C. and 100°C. were 8.5 per cent and 7.1 per cent respectively.Experimental evidence indicated that under the conditions examined (i) only oligomers resulting from interaction between isocyanate groups in the 4‐position were important in dimerisation and trimerisation, and (ii) the trimerisation process was independent of the dimerisation process.Assuming the kinetics of dimerisation to be represented by

equation image
This investigation shows that the dimerisation and trimerisation of 2,4–TDI are not important competing processes in the cure of a polyurethane. However as appreciable amounts of TDID and TDIT can be formed as a result of prolonged storage at elevated temperatures it is important that the purity of the isocyanate is determined immediately before use.
Polycarbodiimides and their derivatives
Authors: Lyman Donald J. , Sadri Nasser 
Published: April 2003

AbstractSeveral polycarbodiimides were prepared by the solution condensation of aromatic and aliphatic diisocyanates in the presence of 1‐phenyl‐3‐methyl‐3‐phospholene‐1‐oxide. In general, the polymers had high melting temperatures and were insoluble in all solvents examined. Water, hydrogen sulfide, alcohols, or primary amines, were reacted with the polycarbodiimide prepared from methylene bis(4‐phenyl isocyanate) to give polyureas, polythioureas, poly‐O‐alkylpseudoures, and polyguanidines respectively.