bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the rheology of concentrated dispersions
Authors: Kammer H. W. , Socher M. 
Published: April 2003

AbstractSteady state rheological properties of concentrated dispersions of metallic particles in different polymer solutions are studied both from a theoretical and an experimental point of view. The results obtained with dispersion media with different interaction parameters χ indicate the strong influence of polymer‐solvent thermodynamics on the rheological behaviour of the dispersions. With stable and neutrally stable dispersions only shear thinning occurs whereas in unstable dispersions dilatancy was observed, depending on the particle concentration.
Study on drying process of microcrystalline cellulose materials
Authors: Cristian G. , Oprea C. V. , Toth C. , Toth I. 
Published: April 2003

AbstractThe influence of the drying agent on the drying process of microcrystalline cellulose was studied and distribution curves of the moisture within the material thickness were established. The values of the moisture migration coefficient were obtained. By means of these values an equation for calculating the moisture migration as a function of the moisture content was derived.
IR spectroscopic analysis of changes in the molecular structure of pitch carbon fibre precursor during oxidation
Authors: Sujak K. , Włochowicz A. , Wysocki M. 
Published: April 2003

AbstractChanges occuring during the process of oxidation of precursor pitch carbon fibres have been analyzed by means of IR spectroscopy. It has been established that a crosslinking process takes place, when the fibres are heated to temperatures above 553 K. Oxidation of the fibres depends on kind of oxidizing medium (oxygen, ozone, air) as well as on duration of oxidation.
Analytische Charakterisierung von Methacrylsilan auf Glasseidengewebe mittels FTIR‐remissionsspektroskopie
Authors: Wiedmann G. , Wustmann B. , Maulhardt H. , Kunath D. 
Published: April 2003

AbstractIm Interesse der Herausarbeitung von Struktur‐Eigenschaftsbeziehungen und für die Bestimmung von Parametern der chemischen Technologie bei der Gestaltung des Grenzschichtbereiches bei verstärkten und gefüllten Polymeren benötigt man qualitative und quantitative Nachweisverfahren. Diese wurden über Farbreaktionen und die chemische Analyse funktioneller Gruppen ausgearbeitet, lassen jedoch Wünsche bezüglich der universellen Anwendung und der Genauigkeit offen. Ausgehend von methodischen Entwicklungen bei der Remissionstechnik in Kopplung mit der Fourier‐Transform‐Infrarotspektroskopie werden die Möglichkeiten des Einsatzes zur Bestimmung von bifunktionellen Verbindungen (Haftmittel auf Glasseidenerzeugnissen) beschrieben. Beim vorliegenden Methacrylsilan sind die Banden der Kohlenstoff‐Wasserstoff‐Valenzschwingungen und die Valenzschwingungsbande der Kohlenstoff‐Sauerstoff‐Doppelbindung auswertbar.
Synthesis of thermotropic polyesters
Authors: Markova G. D. , Kešelava R. G. , Vasnev V. A. , Vinogradova S. V. , Koršak V. V. , Borisov G. , Sevriev Ch. 
Published: April 2003

AbstractPolyesters and copolyesters having thermotropic liquid‐crystalline properties were prepared by acceptor‐catalytic polycondensation. It is shown that the temperature region of the mesophase depends on the structure, ratio of the initial components and their distribution in the macromolecules.
Pecularities of the molecular weight distribution at the one‐ and two‐phase synthesis of linear polyquinoxalines by polycondensation in solution
Authors: Koršak V. V. , Pavlova S. ‐S. A. , Timofeeva G. I. , Krojan S. A. , Krongauz E. S. , Travnikova A. P. 
Published: April 2003

AbstractThe molecular weight distribution of a series of polyphenylquinoxalines obtained by polycondensation of 1,4‐(phenylglyoxalyl)benzene with 3,3′,4,4′‐tetra‐aminodiphenyleneoxide in one‐ and two‐phase systems was determined by fractionation, sedimentation and viscosimetry. The molecular weight distribution of the products of homogeneous polycondensation at 20°C is approximated by the most probable distribution. It became broader with increasing the temperature of reaction to 200°C. In the two‐phase polycondensation the molecular weight distribution was found to be narrower than the most probable distribution.
On the separation of C4‐hydrocarbon mixtures by oligomerization and polymerization. Part I: Proton acid complexes as initiators for isobutene oligomerization
Authors: Pape W. , Hartung H. , Heublein G. , Stadermann D. , Sangalov Yu. A. , Yasman Yu. B. , Nelkenbaum Yu. Ya. , Minsker K. S. 
Published: April 2003

AbstractBRÖNSTED acid‐metal sulfate and BRÖNSTED acid‐LEWIS acid complexes are useful initiators for the oligomerization of isobutene out of C4‐hydrocarbon mixtures. The selectivity of conversion depends on the BRÖNSTED acid content of the complexes, the LEWIS acid and the temperature of oligomerization. The oligomerization is retarded and finally inhibited by increasing amounts of butadiene in the C4‐mixture.
The synthesis and investigation of the properties of copolyimides with six‐membered imide cycles
Authors: Vygodskij Ja. S. , Nagiev Z. M. , Koršak V. V. , Vinogradova S. V. , Urman Ja. G. , Alekseeva S. G. , Slonim I. Ja. , Reinisch G. , Bonatz E. , Jakab Ė. , Till F. , Rafler G. 
Published: April 2003

AbstractThe possibility o f the synthesis of copolynaphthoyleneimides with different microstructure by one step high temperature solution polycyclocondensation is studied. Exchange reactions of polynaphthoyleneimides with different amines are analyzed. It is shown that process of the synthesis of such polyimides is mostly irreversible. Thus, the formation of copolyimides with different block or random microstructures a t high temperatures is possible. Various physicochemical properties of copolyimides with six‐membered imide rings with different microstructure and of corresponding plastics prepared by melt processing are compared.
Thermodynamics of water vapour adsorption by ion‐exchange polyacrylonitrile fibres
Authors: Terlemesian E. , Veleva S. , Arsov A. , Dimov K. 
Published: April 2003

AbstractThe effect of modification of polyacrylonitrile fibres treated with hydrazine hydrate on the thermodynamic parameters of water vapour adsorption is investigated. The size of the monomolecular adsorption layer and the quantity of the bound and free water are determined. They decrease with increasing degree of cross‐linking. The values of the thermodynamic parameters of adsorption are in agreement with the low adsorption power of the investigated materials.
Polymer blends. III. Processing optimization
Authors: Petrovan S. , Rusu M. , Adamescu G. , Lungu M. 
Published: April 2003

AbstractThe paper presents a part of the data obtained in a study on the possibilities of processing optimization of some polymer blends containing polyethylene, polystyrene, poly(vinyl chloride) and ethylene vinylacetate copolymer as compatibility agent. It was found that the screw speed is the most important parameter which influences the melt flow rate and the energy consumption. The maxima of melt flow rate energy consumption at determined energy consumption were determined.
Study of products of hydrolytic copolycondensation of methylvinyl‐ and methylphenyldichlorosilanes by exclusion liquid chromatography method
Authors: Zislina S. S. , Nefedov P. P. , Jul'čevskaja S. D. , Terman L. M. 
Published: April 2003

AbstractBy the method of exclusion liquid chromatography and application of calibration relationship for linear and cyclic individual analoges, the hydrolytic copolycondensation of methylvinyl‐ and methylphenyldichlorsilanes was investigated in dependence on solvent and temperature. Hydrolysis by alcohol leads mainly to the formation of linear high molecular weight oligomers.
Selbstdiffusion von Alkanen in Polyethylen niederer Dichte–Einfluß des Polyethylentyps und der Diffusantgröße
Authors: Fleischer G. , Holstein P. 
Published: April 2003

AbstractMit der Feldgradienten‐Impuls‐NMR wurde die Selbstdiffusion von fünf Alkanen in drei thermisch unterschiedlich vorbehandelten Polyethylenen niederer Dichte untersucht. Die Konzentrationsabhängigkeit des Selbstdiffusionskoeffizienten wurde mit der Theorie des freien Volumens beschrieben. Der Einfluß der unterschiedlichen Kristallinität der Polyethylene drückt sich allein in ihrem freien Volumen aus, das mit wachsender Kristallinität fällt.
Functional polymers. XXX: 2(2,4,6‐trihydroxyphenyl) 2h‐benzotriazole [2(2h‐benzotriazole‐2‐yl)‐1,3,5‐trihydroxybenzene] and benzotriazole‐substituted dihydrocoumarins
Authors: Li Shanjun , Bassett W. , Xi Fu , Vogl O. 
Published: April 2003

Abstract2(2 H‐Benzotriazole‐2‐yl)‐1‐3,5‐trihydroxybenzene was synthesized by improved reactions as the sole product of 2‐nitrobenzenediazonium or 4‐methoxy‐2‐nitrobenzenediazonium chloride condensation and phloroglucinol followed by reductive cyclization of the azo compound. Attempted esterification of the 5‐hydroxy group did not yield the expected 5‐acryloxy compound, but rather 6(2 H‐benzotriazole‐2‐yl)‐5,7‐dihydroxy‐3,4‐dihydrocoumarin, and 6(2H‐4′‐methoxy‐benzotriazole‐2‐yl)‐5‐7‐dihydroxy‐3,4‐dihydrocoumarin, through a Michael‐type condensation of the methylene group of the acrylate to the carbon in 3 position; the dihydrocoumarin was characterized and hydrolyzed to 3(2 H‐benzotriazole‐2‐yl)‐2,4‐dihydroxymelilotic acid. The model compound 5,7‐dihydroxy‐3,4‐dihydrocoumarin and 7‐hydroxy‐3,4‐dihydrocoumarin was also synthesized from resorcinol and phloroglucinol and characterized.
Mechanismus und Kinetik der Imidisierung von Maleinamidsäure‐Copolymeren
Authors: Rätzsch M. , Krahl K. 
Published: April 2003

AbstractDie Cyclisierungsreaktionen (Imidisierung) von Maleinamidsäure‐Copolymeren aus Propen‐und Styren‐Maleinsäure‐amid‐Copolymeren in Dimethylformamid‐Lösung unter Einwirkung von Essigsäureanhydrid werden untersucht. Der unstete Verlauf der Cyclisierungsgeschwindigkeiten mit der Zeit kann auf die als Nebenreaktion ablaufende Bildung von Isoimiden und deren nachfolgende Umwandlung zu den Imiden zurückgeführt werden. Die Zugabe von Natriumacetat beschleunigt die Isoimid‐Imid‐Umwandlung. Aromatische Amine stabilisieren auf Grund des I‐Effektes die Ketoform des Amids, so daß bevorzugt das Imid gebildet wird, während Alkylgruppen auf Grund ihrer Elektronen‐donatorwirkung die Enolform induzieren.
Zur experimentellen Bestimmung breiter Teilchengrößenverteilungen mittels Laserbeugung an elektronenmikroskopischen Aufnahmen
Authors: Büchtemann A. , Dautzenberg H. , Müller I. 
Published: April 2003

AbstractEin früher theoretisch abgeleiteter Algorithmus zur Bestimmung der Parameter breiter Teilchengrößenverteilungen aus dem optischen Beugungsbild elektronenmikroskopischer Aufnahmen wurde an mehreren Modellobjekten experimentell getestet. Die theoretischen und die experimentell ermittelten Parameterwerte stimmen mit guter Genauigkeit überein. Mögliche Fehlerquellen werden eingehend diskutiert.
On heat effects and kinetics of precipitation of polyamide‐6
Authors: Janeczek H. , Turska E. 
Published: April 2003

AbstractHeat effects of precipitation of polyamide‐6 from m‐cresol solutions on adding methanol were measured by means of a microcalorimeter. The heat of precipitation depends on composition of the precipitating system. By means of weight method the kinetics of precipitation was investigated.
Ultrasonic relaxation of poly‐(N‐vinylcarbazole) in solutions. Part I. Solution in 1,2‐dichlorethane
Authors: Juszkiewicz A. , Janowski A. , Ranachowski J. , Wartewig S. , Hauptmann P. , Alig I. 
Published: April 2003

AbstractThe ultrasonic attenuation of PVCz in 1,2‐dichloroethane solution was investigated as a function of temperature and frequency. The relaxation observed is assigned to segmental motions of the chain. The activation enthalpy of this process and the enthalpy difference between the two states are ΔH2* = 14.2 kJ/mol and ΔH0 = 39 kJ/mol, respectively. The high enthaply difference ΔH0 hits at high thermal “stiffness” of the PVCz‐chains. This can be explained by the formation of intramolecular sandwich complexes in PVCz by conformational changes of the relevant carbazole side groups.
Oligomeranaloge Reaktionen. II. Zur Umsetzung von carboxylterminiertem Oligobutadien mit Diandiglycidether
Authors: Härtel E. , Fedtke M. 
Published: April 2003

AbstractFür die Umsetzung von carboxylterminiertem Oligobutadien mit Diandiglycidether werden Geschwindigkeitskonstanten in Abhängigkeit von der Reaktionstemperatur und in Lösungsmitteln unterschiedlicher Polariät bestimmt. N, N‐Dimethylanilin, N,N‐Dimethylbenzylamin und Pyridin werden als Beschleuniger eingesetzt. Es werden Aussagen zum Mechanismus der Säure‐Epoxid‐Reaktion unter den verschiedenen Reaktionsbedingungen getroffen.
Fine structure of the glass transition in amorphous polymers. Part 1. Interpretation of shear curves with the aid of the fluctuation dissipation theorem
Authors: Donth E. , Schneider K. 
Published: April 2003

AbstractThe phenomenological interpretation of shear curves is refined by application of the fluctuation dissipation theorem and the WIENER‐KHINTCHIN theorem. The loss peaks of shear modulus and compliance near the glass transition of amorphous polymers can be attributed to two different molecular motions. An interpretation of the two peaks by one kind of molecular motion (uniform model) would imply that its flanks two logarithmic frequency decads away from the center were significantly more intensive than other molecular motions at these frequencies.
Polycaprolactam filled with short glass fibres and microbeads. I. Preparation of composites by anionic activated adiabatic polymerization
Authors: Horský J. , Kolařík J. 
Published: April 2003

AbstractPolycaprolactam containing glass fillers was prepared by activated anionic adiabatic polymerization. The fillers and coupling agents used reduce the polymerization rate, crystalline fraction and size of supermolecular structures. The reported procedure is suitable for a one‐stage preparation of bulky objects from composite materials.
Untersuchung von intensiv‐verformten Polypropylenfaserstoffen mittels Annihilation von Positronen
Authors: Zaslavskij B. I. , Tatur A. O. , Šantarovič V. P. , Kuznecov Ju. A. , Zelenev Ju. V. , Budnickij G. A. 
Published: April 2003

AbstractDie Spektren der Positronenlebensdauer und der Richtungskorrelation der Annihilationsstrahlung von deformierten Hohlfasern aus Polypropylen wurden im Vakuum, in Luft und in Sauerstoff registriert. Die Analyse der Daten führt zu der Schlußfolgerung, daß unter der Wirkung der Sauerstoffmoleküle große Poren in den deformierten Polypropylenfasern entstehen.
Main features of polypropylene crystallization from the quenched state
Authors: Poddubny V. I. , Lavrentyev V. K. , Sidorovich A. V. , Mikhailova N. V. , Baranov V. G. 
Published: April 2003

AbstractThe structure formation during transition from the quenched into the crystalline state has been studied for isotactic polypropylene by wide‐angle X‐ray scattering. Based on the temperature dependence of the shape of the curve of amorphous scattering the composition of samples with different degrees of crystallinity and different content of paracrystalline form was determined quantitatively. By means of IR spectroscopy it was shown that stretching of quenched polypropylene leads to the freezing of the conformational array in macromolecules. This freezing hinders the transition into the crystalline state upon heating.
Ferrous cellulose thiocarbonate‐persulphate redox system induced graft polymerization of methacrylic acid onto cotton fabric
Authors: Bayazeed A. , El‐Rafie M. H. , Hebeish A. 
Published: April 2003

AbstractGraft polymerization of methacrylic acid onto cotton using ferrous cellulose thiocarbonate‐persulphate redox system was investigated under a variety of conditions. The graft yield was significantly favoured in acidic media as well as by increasing persulphate concentration, methacrylic acid concentration and reaction time. Further, the graft yield obtained by applying of conventional padding methods in the synthesis of the copolymers was investigated.
Kinetics of free radical polymerization of N,N‐dimethyl‐N,N‐diallyl‐ammonium‐chloride in concentrated aqueous solution
Authors: Topčiev D. A. , Malkanduev Ju. A. , Koršak Ju. V. , Mikitaev A. K. , Kabanov V. A. 
Published: April 2003

AbstractRadical polymerization kinetic of N,N‐dimethyl‐N,N‐diallylammoniumchloride was investigated in concentrated aqueous solutions ([MI] = 2 to 5 mol/l, 60°C ) a t low conversions. It was shown that under choosen conditions there was no degradation transfer to monomer reactions in this case and polymerization had square order on persulfate ammonium concentration ([PSA] = 5 · 104 to 5 · 103 mol/l). The viscosity of the initial monomer solution influences greatly the bimolecular termination constant, which leads to sharp and nonlinear increase of the rate of polymerization with increasing monomer concentration.
Bestimmung der kritischen Oberflächenspannung der Adsorption fester Polymere mittels Flüssigkeitsspreitungsdruck
Authors: Kammer H. W. , Gräfe F. 
Published: April 2003

AbstractBenetzungsphänomene werden häufig zur Abschätzung der Oberflächenspannung fester Stoffe herangezogen. ZISMAN führte dazu das Konzept der kritischen Oberflächenspannung der Benetzung γc ein. Die kritische Oberflächenspannung ist ein Charakteristikum der Festkörperoberfläche in bezug auf ihren Kontakt mit Flüssigkeiten. In Analogie dazu wird eine auf der Adsorption basierende kritische Oberflächenspannung γcπ empfohlen und deren experimentelle Bestimmung an Beispielen gezeigt.
Supermolecular organization in liquid crystalline polymers
Authors: Tsukruk V. V. , Shilov V. V. , Lipatov Yu. S. 
Published: April 2003

AbstractFeatures of supermolecular organization in liquid‐crystalline polymers with mesogenic side groups and mesogenic groups in the main chains are described. The nematic and cholesteric mesophase in polymers are shown to be macroscopic ordered phases similar to low‐molecular liquid crystals. Smectic polymers are microheterogeneous systems with complicated levels of supermolecular structures: layered packs and their aggregates.
Molecular weight distribution functions of polystyrene polymerized to high conversion degrees
Authors: Matuszewska‐Czerwik J. , Polowiński S. 
Published: April 2003

AbstractPolymerization of styrene to high degrees of conversion (up to 99.8%) was carried out. The obtained polystyrene was fractionated by distribution between two liquid phases and also by fractionating precipitation. Molecular weights of the fractions were determined and the molecular weight distribution functions were plotted. Bi‐ and trimodal distribution functions were obtained. The results are discussed on the basis of the mechanism of polymerization to high degrees of conversion.
13C‐NMR‐spektroskopische strukturafklärung von Isobuten‐Oligomeren mit Hilfe der APT‐(Attached proton test)‐Technik
Authors: Schütz H. , Radeglia R. , Heublein G. 
Published: April 2003

AbstractAm Beispiel der 13C‐NMR‐spektroskopischen Strukturaufklärung von Oligomeren (n = 2 bis 4) des Isobutens wird ein einfaches Impulsverfahren (APT) vorgestellt. Diese Methode gestattet die eindeutige Zuordnung der Dimer‐, Trimer‐ und Tetramer‐Fraktionen der Isobuten‐Oligomere, die unter speziellen Polymerisationsbedingungen entstehen.
Zur Bestimmung der Mikrostruktur von Trioxan‐1,3‐Dioxolan‐Copolymeren. V. Sequenzanalyse der Struktureinheiten Oxymethylen und 1,4‐Dioxapentamethylen zur Charakterisierung von Transacetalisierungsreaktionen
Authors: Opitz G. 
Published: April 2003

AbstractTrioxan‐1,3‐Dioxolan‐Copolymere wurden mittels 1H‐NMR‐Spektroskopie untersucht, um die Sequenzverteilung der Struktureinheiten Oxymethylen (M) und 1,4‐Dioxapentamethylen (D) festzustellen. Durch Bestimmung von Auftretens‐ und Übergangswahrscheinlichkeiten, Blockzahlen sowie mittleren Sequenzlängen lassen sich Fortgang und Richtung von Transacetalisierungsreaktionen an den Copolymeren quantitativ erfassen.
Investigations on aromatic polyesters with polynaphthalene system in the main chain. XII. Study of copolyesters obtained by the high temperature solution method
Authors: Sęk D. , Zukowski J. 
Published: April 2003

AbstractThe relationship between the reactivity of bisphenolic comonomers, the conditions of high temperature solution copolycondensation reaction, and the chain structure of the resulting terephthalic copolyesters of 4,4′‐dihydroxydinaphthyl‐1,1′ and 2,2‐bis(4‐hydroxyphenyl)propane are investigated.
Vernetzung und Oxidation bei der Elektronenbestrahlung von Polyethylenfolien
Authors: Schipschack K. , Bartl A. , Wuckel L. 
Published: April 2003

AbstractVernetzung und Oxidation sind Konkurrenzreaktionen bei der Bestrahlung von Polyethylen an Luft. Als Kettenreaktion ist die Oxidation auch bei der Elektronenbestrahlung nicht zu vernachlässigen, insbesondere wenn es sich um dünnwandiges Bestrahlungsgut handelt. HDPE ist bei Bestrahlung infolge höherer Stabilität der Radikale und Postoxidation sauerstoffempfindlicher als LDPE. Ausgehend von den bekannten Mechanismen der Strahlenoxidation werden die Bildung und der Zerfall der Peroxyradikale quantitativ beschrieben.
Synthesis, structure and properties of poly[bis‐(4‐vinylphenyl) ether]
Authors: Zaitsev B. A. , Lukasov S. V. , Kiseleva R. F. , Kaliuzhnaya L. M. , Pogodina T. E. , Ushakova I. L. , Sidorovich A. V. 
Published: April 2003

AbstractBis‐(4‐vinylphenyl) ether (BVPhE) was obtained by the polycondensation of bis‐[4‐(1‐hydroxyethyl)phenyl] ether and subsequent dehydration of the resulting polyether. The kinetics of three‐dimensional polymerization of BVPhE in an inert medium and in the presence of air have been investigated by IR spectroscopy and differential scanning calorimetry. It is shown that poly‐BVPhE is a highly crosslinked glassy polymer exhibiting high thermal stability and having a softening point of ≈ 460°C.
Untersuchungen zur radikalischen Copolymerisation von Acrylnitril mit α‐Olefinen. 7. Mitt.: Bestimmung der r‐Werte bei niedrigem und höherem Umsatz ‐ Versuch einer Modellselektion für das System α‐Methylstyren/Acrylnitril
Authors: Schmidt‐Naake G. , Schmidt H. , Berger W. 
Published: April 2003

AbstractDie Quantifizierung der r‐Werte erfolgt durch nichtlineare optimale Anpassung verschidenster ausgewählter Copolymerisationsgleichungen an die experimentellen Daten bei niedrigem und höherem Umsatz mit der Zielstellung einer Modellselektion. Alle diskutierten Zweiparametermodelle liefern r‐Werte, die von der Comonomerzusammensetzung und vom Umsatz abhängig sind. Dreiparametermodelle, wie das „Penultimate Modell”︁, und besonders die Annahme der am Reaktionsort reduzierten Olefinkonzentration können den Modelldefekt in mittleren Zusammensetzungsbereichen der Monomermischung beheben.
Formation of new particles in seeded emulsion copolymerization
Authors: Hagiopol C. , Deleanu Th. , Georgescu M. , Deaconescu I. 
Published: April 2003

AbstractThe synthesis of styrene‐acrylonitrile copolymers by seeded emulsion copolymerization on polybutadiene has been studied. The influence of the emulsifier concentration and of the size of the supporting area on the formation of new particles is demonstrated. Kinetic studies and particles size measurements indicate the development of the reaction after the formation of new particles.
Investigation of the radiation‐induced oxidation of thick polyethylene samples by measuring the self‐diffusion coefficient of macromolecules
Authors: Belousova M. V. , Skirda V. D. , Zgadzai O. E. , Maklakov A. I. , Potapova I. V. , Romanov B. S. , Rumyanthev D. D. 
Published: April 2003

AbstractLayer‐by‐layer study of commercial polyethylene samples, γ‐irradiated in air, was carried out by measuring the selfdiffusion coefficient Ds of macromolecules by means of pulsed field gradient NMR. On the basis of chemical reactions of the radicals an equation is obtained, describing the dependence of Ds on the layer depth in the kinetic and diffusive oxidation regions. The effect of crystallinity, radiation intensity and temperature on the thickness of the oxidized layer is examined.