bluuebunny/crossref_metadata_2025_split huggingface dataset:
Properties and role of benzoquinone imines in polymer stabilization
Authors: Pospíšil Jan 
Published: April 2003

AbstractQuinone imines are formed from aromatic amine antidegradants as a consequence of chemical transformations of the latter during the stabilization of hydrocarbon polymers. Quinone imines are deep coloured compounds and contribute to the antidegradant activity of the parent amines. The main interest is devoted to benzoquinone diimines (BQDI), generated from N,N '‐disubstituted 1,4‐phenylenediamines (PD). BQDI are antioxidants in unsaturated hydrocarbons, undergo hydrolytic deamination, addition and cyclization reactions, react with 2,6‐dialkylphenols, thiols and C‐centered radicals. PD are regenerated from BQDI in redox reactions. The active role of BQDI in antifatigue processes in rubbers has been explained using product analysis. BQDI account for staining and discoloring properties of PD but are not harmful to the polymer stability.
New oligomers with isatin. Condensation reactions of thiophene and 2,2′‐bithiophene with isatin
Authors: And Francisco Martinez , Naarmann Herbert 
Published: April 2003

AbstractA systematic study of the well‐known indophenin reaction between isatin and thiophene was extended to embrace bithiophene. The products of the reactions were isolated and characterized by FT‐IR, UV, 1H‐NMR, 13C‐NMR, and GPC. The values of the thus determined molar masses and molar mass distributions differed from the data given in the literature. The reaction conditions – solvent, temperature, and concentration – are of crucial importance for the course of the reaction and the products obtained.New structures suggested for the oligomeric reaction products agree with all the analytical data. The reactions between isatin and thiophene (bithiophene) are explained schematically.
Partikelgrößenanalyse von dispersen farbstoffsystemen, II. Photonen‐korrelations‐spektroskopie an latexsuspensionen und ‚modellblindfärbungen’︁ von polyethylenterephthalat‐fasern
Authors: Brünger Harald , Schollmeyer Eckhard 
Published: April 2003

AbstractAls Vorstufe zur Teilchengrößenanalyse von Farbstoffbädern mittels Photonen‐Korrelations‐Spektroskopie werden Latexsuspensionen untersucht. Eine Simulation einer Färbung von Polyestermaterial mit Dispersionsfarbstoffen wird durch eine ‘Modellblindfärbung’ unter Benutzung von Latexsuspensionen bei unterschiedlichen Farbbadtemperaturen nachgestellt. Die sich innerhalb des ‘Färbebades’ ergebenden Partikelgrößenverteilungen werden mit Hilfe der Photonen‐Korrelations‐Spektroskopie analysiert.
Modification of polyamide 6 with hycar ATBN
Authors: Maroušek Vladimír , Svoboda Petr , Králišek Jaroslav 
Published: April 2003

AbstractThe preparation of block copolymers from 6‐caprolactam and a liquid amine terminated butadiene‐acrylonitrile copolymer Hycar ATBN 1300X21 having higher notched impact strength than ordinary poly(6‐caprolactam) was studied. In the polymerization of 6‐caprolactam initiated by an adduct of phosphoric acid with 6‐caprolactam the influence of initiator concentration (0– 50 mol‐%) and Hycar ATBN 1300X21 concentration (0–5 wt.‐%) in the polymerization charge, of polymerization time (4 – 72 h) and of temperature (200–280°C) on the 6‐caprolactam conversion and on the properties of the copolymers formed were followed. Notched impact strength of the block copolymers prepared under optimized conditions was as high as 13.5 kJ·m−2.
Sphärische ionotrope gele carboxygruppenhaltiger cellulosederivate als trägermaterialien für biologische wirkstoffe, IV. Synthese von carboxycellulose und ionotrope gelbildung mit calciumionen
Authors: Heinze Thomas , Klemm Dieter , Loth Fritz , Nehls Irene 
Published: April 2003

AbstractNatriumcarboxycellulose mit einem Substitutionsgrad bis 0,8 kann durch Oxidation von Cellulose mit einem Polymerisationsgrad im Bereich von 170 bis 1500 mit NaNO2/H3PO4 und anschließender Behandlung mit NaBH4 hergestellt werden. Das Ausmaß der Oxidation steigt mit wachsender Molmasse des Ausgangsmaterials. IR–und NMR‐Untersuchungen zeigen, daß nur das C‐6‐Atom der Anhydroglucoseeinheit oxidiert ist. Die Natriumcarboxycellulosen weisen eine hohe Tendenz zur ionotropen Gelbildung auch in sphärischer Form mit Calciumionen auf. Die mechanisch stabilen Gele werden durch Quellungsuntersuchungen und REM charakterisiert.
Graft polymerization of 4‐vinylpyridine onto cellulosic fibres by the ceric ion method, II. The ph effect
Authors: Leza M. Lourdes , Casinos Ismael , Guzmán Gonzalo M. 
Published: April 2003

AbstractThe effect of pH on the graft polymerization of 4‐vinylpyridine (4‐VP) onto cellulose and on partially carboxymethylated cotton (PCMC) initiated by ceric ammonium nitrate (CAN) in dilute nitric acid was examined. The grafting parameters grafting efficiency (GE), graft yield (G), graft frequency (GF), and ceric ion consumption (Ce(IV)c) were studied as a function of nitric acid concentration. Also the effect of pH on the graft polymerization was examined and the total nitrate ion concentration was maintained high and constant at 0.86 mol/1 by addition of sodium nitrate. Maximum grafting and total conversion occurred at pH 1, but these values were smaller than the ones obtained in the previous case. For comparison some experiments were carried out using ceric sulfate as initiator.
Visco‐Elastic properties of blends of crystalline polymers possessing a weak phase coupling. Studies on blends of poly(ethylene) and poly(oxymethylene)
Authors: Pabst A. , Wendorff J. H. 
Published: April 2003

AbstractThe investigations reported in this paper aimed at evaluating the impact of a weak interfacial strength on visco‐elastic properties in multiphase polymer blends both in the linear and nonlinear deformation regime. Blends of poly(ethylene) and poly(oxymethylene) were used as model systems. The particular choice of the components of the blend was based on the fact that the two components are incompatible, possess strong interfacial energies and thus narrow and weak interfacial layers, and finally that their individual visco‐elastic properties are within the same order of magnitude. This allows to evaluate the contributions of the phase boundaries to the visco‐elastic properties in a transparent way.We investigated the visco‐elastic properties of blends of various compositions by analyzing the stress‐strain behavior, the dynamical torsional behavior as well as by determinating their cyclic stress‐strain behavior. The experimental finding is that most of the properties studied vary linearly with the composition and are not influenced by the weakness of the interfacial strength–contrary to the expectation. An exception is the elongation at break which varies nonlinearly with the composition and which shows a minimum value at intermediate compositions. The impact of a weak phase coupling on visco‐elastic properties is thus rather limited.
Solution properties of polyacrylic esters. I. Light scattering and viscosity measurements in tetrahydrofuran
Authors: Penzel Erich , Goetz Norbert 
Published: April 2003

AbstractDilute THF‐solutions of different fractions of polymers of methyl, ethyl, n‐propyl, n‐, i‐ and t‐butyl, n‐hexyl, 2‐ethylhexyl, and lauryl acrylate, prepared by solution polymerization in benzene, were studied by light scattering and viscosity methods. Poly(acrylic acid) was examined in dioxane. For the different polyacrylic esters the [η]‐Mw‐relations were established and the dependence of the radius of gyration <r2w> on the molecular weight was determined.
Eine spektroskopische Methode zur Messung der Ammoniak‐Permeabilität in Polymerfilmen
Authors: Müller Franz Werner , Schiller Kurt , Marx Jörg 
Published: April 2003

AbstractEs wird eine neuartige spektroskopische Methode zur Messung der Ammoniak‐Permeabilität in transparenten Polymerfilmen vorgestellt. Sie beruht auf dem quantitativen Nachweis des den Testfilm durchdringenden Ammoniaks in einer darunter befindlichen Sensorschicht mit Hilfe der NH3‐empfindlichen Sonde 4‐Nitrophenol. Aus dem Anstieg der Extinktion mit der Zeit (ΔE/Δt) in der Sensorschicht wird die Permeabilität (P) und aus der Verzögerungszeit (lag time (t1)) der Diffusionskoeffizient (D) berechnet. Die Eignung der Methode wird durch Vergleich mit Literaturwerten belegt. Die aus t1 zugänglichen Diffusionskoeffizienten stimmen sehr gut mit denen überein, die mit der Sorptionsmethode gefunden werden.Die Temperaturabhängigkeiten von P und D in mehr als fünf verschiedenen Polymeren (CDA, PVB, PVAc, PVC und in verschiedenen Polyvinylalkoholen) zeigen, daß Besonderheiten im Temperaturgang der Permeabilität aus dem vom Aufbau des Polymeren stark abhängigen Verhalten der NH3‐Löslichkeit (P/D) resultieren.
Urease immobilized on aminated butyl acrylate‐ethylenedimethacrylate copolymer
Authors: Krajewska Barbara , Leszko Maciej , Zaborska Wieslawa 
Published: April 2003

AbstractUrease was covalently immobilized on a new acrylic enzyme carrier: aminated butyl acrylate‐ethylenedimethacrylate copolymer. The enzyme retained 56% of its original activity. The properties of the free and immobilized urease were determined and compared. The Michaelis constant was found to be higher for the immobilized urease than for the free one, while maximum reaction rate was lower for the immobilized enzyme. The stability of urease against change in pH was considerably improved by the immobilization. The immobilized urease showed very good storage stability and reusability. Resistance of the enzyme against heat inactivation at 70°C, however, was not found to be improved.
Weld lines in injection moulded polypropylene parts. Mechanical properties morphology relationships
Authors: Wenig Werner , Singh Devinder , Botzen Gerald , Moslé Hüter‐Georg 
Published: April 2003

AbstractThe morphology of polypropylene plaques containing a weld line, has been investigated by x‐ray wide and small angle scattering, light scattering and polarization microscopy. The results are correlated to mechanical values obtained from tensile tests. While the lamellar morphology is of neglectable influence, it is found, that the mechanical properties of the samples are strongly influenced by the spherulitic structure. Clustering of β‐type spherulites and strong morphological inhomogeneities in the vicinity of the weld line are the primary reason for the mechanical weakening of the plaques. The temperature of the mould has a strong effect on the spherulitic structure and thus on the tensile properties of the samples.
Syntheses and properties of UV‐autocurable BTDA‐based polyester multiacrylates. II. Effect of polyol type and reactive monomer
Authors: Chiang Wen‐Yen , Chan Shao‐Ching 
Published: April 2003

AbstractSeveral families of UV‐autocurable benzophenone tetracarboxylic dianhydride (BTDA)‐based polyester multiacrylate oligomers containing pendant glycidyl methacrylate (GMA) were synthesized and the effects of acrylic functionality and polyol type on their properties were investigated. The obtained autocurable oligomers possess good pot life and are cured rapidly when exposed to ultraviolet (UV) radiation without the addition of photoinitiator or photosensitizer. Different polyols were used to obtain wide range properties of cured multiacrylate oligomers with a glass transition temperature (Tg) range of 84–130°C. A further modification of the multiacrylate oligomers was obtained by mixing them with reactive monomers having different molecular structure and methacrylic functionality.
The problem of determination of hydroxy groups in poly(oxyethylene) diols by using the phenylisocyanate method
Authors: Novák P. , Ilavský M. , Špašek P. , Bouchal K. , Pavlas P. 
Published: April 2003

AbstractTraces of potassium acetate present in commercial poly(oxyethylene) diols (Fluka) were shown to catalyze the cyclotrimerization reaction of isocyanates. This reaction interferes with the determination of hydroxy groups by using the phenylisocyanate method. After the removal of potasium acetate (e. g. by means of ion exchangers) the phenylisocyanate method gives reproducible results which can be compared with those obtained by other methods. Reaction conditions suitable for the determination of OH groups in poly(oxyethylene) diols were found.
Alcoholysis of esterlinkages in solution
Authors: Hettrich Wieland , Joel Detlef , Becker Hans , Wehrstedt Carla 
Published: April 2003

AbstractPoly(alkylene adipate)diols having molar masses of 1500, 2000 and 3000 were stored at temperatures of 25 and 60°C in the presence of low amounts of different alcohols and some polyurethane (PUR) catalysts, such as dibutyltindilaurate (DBTL), dibutyltindiethoxide (DBTEO), dibutyltinoxide (DBTO), and 1,4‐diazabicyclo[2.2.2]octane (DABCO). Alcoholysis was studied using either ethyl acetate (EA) or toluene as solvent. The results were compared with those obtained by examining the behaviour of several dialkyl adipates and ethyl acetate under identical conditions. The alcoholysis in the presence of the tin catalysts proceeds at the same reaction rate without significant decomposition of the catalyst, whereas DABCO is practically inactive. The nucleophilic activity of the alcohols depends on their bulk size rather than their basicity. The resistance of polyalkylene adipates to transesterification increases with the increasing alkyl chain length of diol units in polyester. A partial transesterification of dialkyl adipates takes place too, in spite of ethyl acetate being present in excess.
Separation of liquid mixtures by using polymer membranes. II. Water‐alcohol separation by pervaporation through porous PVA membranes
Authors: Hu Chun‐Min , Chiang Wen‐Yen 
Published: April 2003

AbstractThe permeation and separation characteristics of alcohol/water systems through porous PVA membranes were investigated. Porous PVA membranes with different pore size and number were prepared by solution blending of PVA with several synthesized polymers or copolymers, such as polyacrylic acid, polyacrylamide, polyacrylonitrile, and methylmethacrylate‐co‐maleic anhydride, etc. Then casting, and finally extracting the blended polymers or copolymers by solvent from the membranes. The dependency of both permeation and separation on the molecular size and shape of the permeating species was dicussed qualitatively. Moreover, the permselectivity was investigated with attention to the feed composition of alcohol/water mixture and the effect of pore size and number. The selectivity was found to depend on the weight ratio and the molecular weight of polymer introduced to the membrane. When the weight ratio of polymer introduced into the membrane was larger than 0.1, methanol was permeated through membrane preferentially in methanol/water system, and the separation factor increased with increasing the methanol feed concentration. On the other hand, membrane had a selective permeability for water in the other alcohol/water systems. The influence of operating conditions was also studied.
Study of ternary component intermacromolecular complex formation involving Ni(II), phenolic copolymer and acrylic copolymer
Authors: Chatterjee S. K. , Ghosh Sudipta , Yadav D. , Farahani B. V. 
Published: April 2003

AbstractTwo phenolic copolymers and a methacrylic acid‐methacrylamide copolymer have been synthesized and characterized by known methods. The respective comonomer units of the copolymers enter into complex formation through hydrogen bonding and ion‐dipole interactions. The interaction of the intercopolymer complex with a typical transition metal ion (e. g., Ni(II)) has been studied by several experimental techniques, e. g. viscometry, potentiometry, conductometry, IR, and UV spectrophotometry. Formation of metal‐intercopolymer complexes of distinct stoichiometries have been predicted, and some schemes have been suggested to explain the mode of interaction between the components.
The properties of polymer blends of the β‐modification of polypropylene and an elastomer
Authors: Varga József , Garzó Gábor 
Published: April 2003

AbstractBlends of β‐polypropylene with elastomers have been prepared under laboratory and processing technological conditions. As a result of the elastomer addition the temperature interval favourable for the formation of the β‐modification became narrower. Blends have spherulitic structure like pure β‐PP. The elastomer has negligible effects on the size of spherulites and on the rate of crystallization. Optical microscopy and DMA measurements revealed that the blends were two‐phase systems in the solid state.The mechanical properties of the blends are close to those of β‐PP in the investigated composition range. Increasing elastomer content reduced the strength characteristics but considerably improved cold impact resistance, the most beneficial combination containing about 8–12% of elastomer. A mathematical relationship has been proposed describing the relationship between impact strength and elastomer content. The dependence of the structural characteristics and macroscopic properties of elastomer‐modified β‐PP blends on the composition and on the temperature is similar to that of the identical β‐PP blends.
Anwendung diskreter diffusions‐adsorptions‐modelle auf das färben von polyacrylnitrilfasern mit kationischen farbstoffen
Authors: Engelmann Uwe , Schmidt‐Naake Gudrun , Pippel Winfried , Flath Hans‐Joachim 
Published: April 2003

AbstractAuf der Grundlage eines Zellenmodells der Faser mit transienten und adsorbierenden Zuständen wurden ein Diffusions‐Adsorptions‐Modell mit nach jedem Zeitschritt eingestelltem Adsorptionsgleichgewicht sowie ein Färbeprozeßmodell mit zeitabhängigem Diffusions‐ und Adsorptionsprozeß abgeleitet. Für das Färben einer Polyacrylnitrilfaser mit 6 verschiedenen kationischen Farbstoffen bei 93°C und 98°C erfolgte die Bestimmung der Modellparameter — Diffusionskoeffizienten und kinetische Konstanten von Ad‐ und Desorption — durch Anpassung an experimentelle Aufziehkurven unter Verwendung der Parameter der Adsorptionsisotherme nach Langmuir. Die erhaltenen Diffusionskoeffizienten liegen in der Größenordnung von 10−9 cm2/s. Der geringe Unterschied der Ergebnisse der beiden unterschiedlichen verwendeten Färbemodelle stützt die Annahme, daß die Diffusion den geschwindigkeitsbestimmenden Schritt darstellt. Beim Färben mit Crypurrot GTL bei 93°C zeigte sich jedoch, daß die Adsorptionsgeschwindigkeit nicht in jedem Fall vernachlässigt werden kann.
Thermische und mechanische eigenschaften von polyurethanen mit mesogenen diolkomponenten
Authors: Lorenz R. , Els M. , Haulena F. , Schmitz A. , Lorenz O. 
Published: April 2003

AbstractEs wurden thermische und mechanische Eigenschaften von nichtsegmentierten und segmentierten Polyurethanen untersucht, die als Diolkomponente 4,4′‐Di(ω‐hydroxyalkoxy)biphenyle mit unterschiedlicher Spacerlänge enthalten. DSC‐Messungen zeigten, daß die bei den nichtsegmentierten Polyurethanen auftretenden thermischen Übergänge auch bei den segmentierten beobachtet wurden, allerdings unter Verschiebung zu tieferen Temperaturen. Polarisationsmikroskopische Untersuchungen an den nichtsegmentierten Polyurethanen weisen auf das Vorliegen von LC‐Phasen hin.Die Spannungswerte von Filmen segmentierter Polyurethane nahmen mit steigender Spacerlänge insbesondere bei Temperaturen ≤40°C zu. Dies wird auf eine mit steigender Spacerlänge erfolgende Entkopplung der Bewegungen von mesogenem Bereich und Urethanteil zurückgeführt. Die Entkopplung fördert gleichzeitig die Bildung größerer Domänen des Mesogens. Oberhalb eines temperaturabhängigen kritischen Spannungswertes treten Fließvorgänge auf.Eine chemische Vernetzung unterhalb der thermischen Übergänge führt zu einer Verbesserung der mechanischen Filmeigenschaften, da sich die durch Domänen des Mesogens bewirkte physikalische Vernetzung der chemischen überlagert. Die Untersuchung erfolgte an einem Polyurethan mit COOH‐Gruppen, das bei Temperaturen unterhalb bzw. oberhalb der thermischen Übergänge mit einem Melaminharz vernetzt wurde.
Molar mass distribution determination of natural rubber and masticated natural rubber by gel permeation chromatography
Authors: Bartels Holger , Hallensleben Manfred L. , Pampus Gottfried , Scholz Günter 
Published: April 2003

AbstractA procedure for analyzing natural rubber via gel permeation chromatography without separating any gel was elaborated. Natural rubber and masticated natural rubber were studied by Mooney‐viscosity, solution viscosimetry and gel permeation chromatography. We show that the determination of the molecular mass distribution can easily and quickly be done by this method and it is urgently needed for the inquiry into the mechanisms of mastication and as a method of quality control of natural rubber in rubber industry.
A staining procedure for the detection of oxidized sites in polyolefins
Authors: da Costa Ricardo Aurélio , Coltro Leda , Galembeck Fernando 
Published: April 2003

AbstractOxidized areas in polyolefin (PE, PP, EPDM) solids can be located by immersion in a warm isopropanolic solution of Sudan III and methylene blue, followed by observation of the solid discoloration pattern. Oxidized sites are stained blue, nonoxidized sites are stained pink. UV/Vis transmission and photoacoustic spectra can be obtained from the stained samples.
Oberflächenstrukturierung polymerer fasern durch UV‐laserbestrahlung. 8. Schwellenverhalten der laserinduzierten oberfläauchenstrukturierung von poly(ethylenterephthalat)
Authors: Kesting W. , Bahners T. , Knittel D. , Schollmeyer E. 
Published: April 2003

AbstractBei UV‐Excimer‐Laserbestrahlung von biaxial verstreckten Poly(ethylenterephthalat) (PETP)‐Folien durch einen Spalt oder durch kreisförmige Blenden entstehen unter geeigneten Bestrahlungsbedingungen die bekannten charakteristischen Strukturierungen, welche durch Fresnelsche Beugungserscheinungen modifiziert sind. Die Beugung des Laserlichtes führt zu lokalen Intensitätsunterschieden auf der PETP‐Oberfläche. Unter Ausnutzung dieses Beugungseffektes wurde eine higher nicht gemessene Grenzenergie für die laserinduzierte Ausbildung der Oberflächenmorphologie von PETP bestimmt. Wesentlich ist hierbei, daß diese Strukturschwellenenergie deutlich unterhalb der extrapolierten Ablationsschwellenenergie von PETP liegt. Darüber hinaus wird an Elastomerfasern aufgezeigt, daß die Grenzenergie zur Strukturbildung auch von der Größe eines extern aufgebrachten Spannungsfeldes abhängt.
Synthesis of pyrrones based on the reduction and cyclization of their o‐nitrosubstituted polyimides precursors
Authors: Sideridou‐Karayannidou Irini , Karayannidis Giorgos 
Published: April 2003

AbstractPyrrones derived from 1,2,4,5‐tetraaminobenzene and pyromellitic dianhydride or 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride were prepared by catalytic reduction and cyclization of the poly(o‐nitro)imides, obtained by polycondensation of 1,3‐dichloro‐4,6‐dinitrobenzene with the dipotassium salt of pyromellitic diimide or 3,3′,4,4′‐benzophenonetetracarboxylic diimide. These polymers were characterized by slightly better thermal stability as compared with the polymers of the same structure obtained by conventional methods. The model compound for these polymers has been also synthesized by catalytic reduction and cyclization of 1,3‐bis(phthalimido)‐4,6‐dinitrobenzene.
Separation of iridium from platinum using a modified glycidyl methacrylate copolymer with diethylamino groups
Authors: Kálalová E. , Thuy Pham 
Published: April 2003

AbstractA macroporous glycidyl methacrylate — ethylene dimethacrylate copolymer with sorption‐active diethylamino groups proved to suit well for the separation of two component mixtures of chloro complexes [lrCl6]2‐ and [PtCl6]2‐. A method for the separation was worked out, based on the reduction of the two complex ions with an aqueous solution of SO2, after which iridium(III) is easy to elute (1 M HCI) where as platinum(II) is only eluted with 5 M HCI. The reaction patterns are given, supported by spectroscopic evidence.