bluuebunny/crossref_metadata_2025 huggingface dataset:
Charge transport mechanism in poly(vinyl alcohol) ‐ poly(vinyl pyrrolidone) polyblend films
Authors: Rao V. V. R. Narasimha , Kumar C. Ramesh , Laxminarayana K. , Rao B. Subba
Published: April 2003

Polyblend films of poly(vinyl alcohol) and poly(vinyl pyrrolidone) were prepared from solutions of the homopolymers. The steady‐state electrical conduction was studied in the temperature range from 309 K to 450 K at the field strength of 0.75 to 46.5 · 106 V/m using different electrode materials. The charge transport is attributed to the injection of charge carriers from the electrode materials into the dielectric according to the Richardson‐Schottky mechanism and their subsequent trapping and release according to the Poole‐Frenkel mechanism.
Problems connected with the evaluation of the perfection of polymer crystalline structure with poly(ethylene terephthalate) as an example
Authors: Jeziorny A.
Published: April 2003

The perfection of the crystalline structure of PETP fibres was evaluated by means of two different X‐ray methods. The values of the perfection index of the crystalline structure obtained with the method proposed by Ruland were correlated with the parameters characterizing the fold surface layers of the crystallites, particularly with the free energy of these layers. On the basis of the found correlation, the conclusion was drawn that the value of the perfection index depends on the order of the macromolecules within the fold surface layers of the crystallites.
Liquid crystallinity of main chain polyurethanes based on 4,4′‐azobenzenediisocyanate
Authors: Kossmehl G. , Hirsch B.
Published: April 2003

Polyurethanes were synthesized from 4,4′‐azobenzenediisocyanate with mono‐, di‐, tri‐ and tetraethylene glycol and their thermal properties were investigated. One of the resulting polymers, poly(oxycarbonylimino‐4,4′‐azobenzenediyliminocarbonyloxyethyleneoxyethyleneoxyethylene) shows a liquid crystalline phase higher than 225°C, determined by DSC and polarizing microscopy.
Modification of the physical properties of paper wood pulp by grafting with α,α‐dihydroperfluoroheptyl methacrylate
Authors: Yousef M. A.
Published: April 2003

Paper grade wood pulp was grafted with α,α‐dihydroperfluoroheptyl methacrylate by using a KMnO4 redox system. The effects of different reaction parameters on the grafting process are investigated. The prepared samples exhibit excellent oil and water repellency.
The structural effects of cold crystallization of poly(ethylene terephthalate)
Authors: Jeziorny A.
Published: April 2003

Poly(ethylene terephthalate) fibres of different drawing ratio were investigated. The parameters of cold crystallization were determined from the DSC thermograms. The parameters of the supermolecular structure of the samples were determined by X‐ray technique. On the base of the suitable linear regression relations it was stated that cold crystallization occurs within the fold surface layers of the crystallites. The effects of cold crystallization are changes of the molecular order within the surface layers. Direction and magnitude of these changes decide the initial melting temperature of the sample.
Homo‐ und Copolymerisation von Butadien und Isopren mit Ni/Ti/Al‐ und Ni/B/Al‐Katalysatorsystemen. III. Copolymerisation Butadien/Isopren mit einem Ni/B/Al‐Katalysator
Authors: Gebauer U. , Oberdörfer A. , Schütz M. , Gehrke K.
Published: April 2003

Die Copolymerisation von Butadien und Isoprcn mit dem ZIEGLER‐NATTA‐Katalysator Nickeloctoat‐Bortrifluoridetherat‐Aluminiumtriethyl in Toluen wurde untersucht. Diese Copolymerisationsreaktion ist über den gesamten Bereich der Ausgangsmonomenusammensetzung realisierbar. Dic Bestimmung der Copolymerzusammensetzung erfolgte mittels 1H‐NMR‐Spektroskopie. Die Bestimmung der r1‐ und r2‐Werte erfolgte iiber eine integrierte Form der Grundgleichung nach MEYER und SKEIST. Isopren wirdlangsamer eingebaut als Butadien (rBD > rt), bewirkt eine Abnahme des Umsatzes und hat transregulierende Wirkung.
Zum Einfluß von Gelkörpern auf die Symplexbildung von Na‐Carboxymethylcellulose
Authors: Kötz J. , Borrmeister B. , Philipp B.
Published: April 2003

Mittels turbidimetrischer und konduktometrischer Titration wurde die Symplexbildung zwischen verschiedenen kationischen Polyelektrolyten und Carboxymethylcellulose‐Lösungen unterschiedlichen Gelpartikelgehaltes untersucht. Der Gelgehalt beeinflußt im Falle von Poly‐DMDAAC als kationischer Komponente die Form der Trübungskurve, wobei sich ein Zusammenhang zwischen der Länge des steil verlaufenden Anfangsteils der Kurve und der Höhe des Gelanteils ergibt. Präparative und analytische Anwendungsmöglichkeiten dieser Beobachtungen werden diskutiert.
The governing factors in heterogeneous matrix monequilibrium copolyesterification
Authors: Kuznetsov A. I. , Ignatov V. N. , Vasnev V. A. , Gribova I. A. , Vinogradova S. V. , Gureeva G. I. , Lavrukhin B. D.
Published: April 2003

A systematic study has been carried out on the kinetic and structural matrix effects in acceptor‐catalytic polyesterification conducted in the presence of fillers. The filler exerts a different influence on the reactivity of aromatic and aliphatic hydroxylated compounds, which is reflected in the microstructure of the synthesized copolyesters. Filler introduction at the stage of polymer synthesis is established to raise its molecular mass characteristics and to improve the antifrication properties of filled systems.
Thermal conversion of filled polymer compositions of aminoplast
Authors: Mgeladze B. M. , Sh. Papava G. , Pkhakadze N. S. , Kvantrishvili G. E. , Dokhturishvili N. S. , Maisuradze N. A.
Published: April 2003

Thermal treatment of polymer compositions of aminoplast on the basis of diatomite leads to the increase of the rate and depth of curing due to the catalytic action of the filler. These polymer compositions are capable to injection moulding and yield plastic materials with good dielectric properties.
Zum Löseverhalten von Polyester‐Polyurethanen
Authors: Hettrich W. , Joel D. , Gnauck R. , Pohl G.
Published: April 2003

Der Einfluß des Hartsegmentgehaltes linearer Toluen‐2,4‐diisocyanat‐Polyester‐PUR mit M̄n < 50000 auf deren Lösungseigenschaften wird untersucht und mit dem thermoanalytisch bestimmten Zustand der Phasensegregation verglichen. Die Morphologie dieser Formstoffe wird durch schwach polare Lösungsmittel signifikant verändert. Zeitliche sowie thermische Alterung unterhalb 70°C bewirkt dagegen keine Veränderung des Entmischungszustandes.
Untersuchungen zur Kondensation von Harnstoff mit Formaldehyd in konzentrierten wäßrigen Lösungen
Authors: Starzyńska K.
Published: April 2003

Zwei‐ und Dreistufenprozesse zur Kondensation von Harnstoff‐Formaldehyd‐Harzen bei Einsatz von Harnstoff bzw. Harnstoff‐Formaldehyd‐Konzentraten wurden untersucht. Die Änderungen des Gehaltes an unreagiertem Formaldehyd, Hydroxymethyl‐, Dimethylenether‐ und Methylengruppen in den einzelnen Stufen der Kondensation wurden bestimmt. Unterschiede im Verlauf des Kondensationsprozesses wurden beim Einsatz eines Gemisches von Harnstoff und Harnstoff‐Formaldehyd‐Konzentrat bzw. eines Gemisches von Harnstoff und Formalin mit ähnlicher Zusammensetzung gefunden.
Macrocyclic compounds as polymer light stabilizers
Authors: Siling S. A. , Margolin A. L. , Ya. Kalontarov I. , Vinogradova S. V. , Niyazi F. F. , Chaiko Yu. V. , Dzhumayev Sh. S.
Published: April 2003

The efficiency and mechanism of light stabilization have been investigated for macroheterocyclic compounds (hexazocyclanes) and for polymers with macroheterocycles in the chain (poly(hexazocyclanes)). The hexazocyclane based on phthalodinitrile and p‐phenylene diamine proved to be the most active UV stabilizer for acetyl cellulose. It acts by the mechanisms of UV screening and photosensitization. The photostabilizing activity depends on the structure of the macrocyclic compound.
Slow reversible collapse of gels based on copolymers of acrylamide and acrylic acid
Authors: Budtova T. V. , Belnikevich N. G. , Buyanov A. L. , Revelskaya L. G. , Petropavlovsky G. A. , Frenkel S. Ya.
Published: April 2003

The behaviour of highly swelling hydrogels based on a copolymer of acrylic acid and acrylamide has been studied in solutions of low molecular weight salts. An explanation of the mechanism for gel collapse and swelling in solutions of various metals is presented. The dependences of the sorption rate and the amount of sorbed copper ions on the particle size of the dry powder and on the swelling coefficient were established.
Lichtinduzierte Polymer‐ und Polymerisationsreaktionen. 40. Untersuchungen zur direkten Photopolymerisation von Methylacrylat durch aromatische Ketone – Wirkung von 1,4‐Diradikalen und Ketylradikalen
Authors: Timpe H.‐J. , Krohfeld K.‐P.
Published: April 2003

Die durch Lichtanregung von Benzophenon (BP), Fluorenon (FI), Xanthon (X), Thioxanthon (TX), 3,6‐Bis(dimethylamino)thioxanthon (BTX), Acridon (Ac) oder N‐Methylacridon (MAc) in Acetonitril/Methylmethacrylat‐Mischungen erhaltenen Polymere wurden isoliert und bezüglich ihrer Endgruppen analysiert. Dazu dienten UV/VIS‐Spektren in Kombination mit Protonierungs‐ und Hydrolysereaktionen. Es konnte bewiesen werden, daß im Falle des Fl ein 1,4‐Diradikal, gebildet durch Addition des Ketontripletts an das Monomer, die Polymerisationskette initiiert. Bei TX, BTX, Ac und MAc ist diese Reaktion im untergeordneten Maße an der Polymerbildung beteiligt. Es überwiegt, bei BP und X ausschließlich, eine Initiierung durch Radikale, die durch Wasserstoffabstraktionsreaktionen des Ketontripletts entstehen. Die so entstchenden Ketylradikale zeigen ein sehr differenziertes Verhalten. Während sie bei Ac und MAc in der Abbruchreaktion Wasserstoffatome übertragen, erfolgt bei Fl überwiegend Radikalkombination.
Untersuchungen zur Bildung wasserlöslicher Cellulosephosphate durch homogene Acylierung im System Cellulose N2O4/DMF. 1. Mitt.: Problemstellung und Ergebnisse zur Acylierung mit POCl3
Authors: Wagenknecht W. , Philipp B. , Nehls I. , Schnabelrauch M. , Klemm D. , Hartmann M.
Published: April 2003

Nach Auflösung in einem N2O4/DMF‐Gemisch unter partieller Bildung des Nitritesters wurde Cellulose unter homogenen Reaktionsbedingungen mit POCl3 in Gegenwart von Triethylamin bis zu DSp‐Werten von etwa 1 phosphoryliert. Wasserlösliche Produkte wurden im DSp‐Bereich zwischen 0,3 und 0,6 nach einer Behandlung des Reaktionsproduktes in einem protischen Medium erhalten.
13C‐NMR‐spektroskopische Untersuchungen zur Phosphatierung von Celluloseprodukten im System H3PO4/Harnstoff
Authors: Nehls I. , Loth F.
Published: April 2003

Auf Basis von gemahlenem Fichtensulfitzellstoff, mikrokristalliner Cellulose und Perlcellulose sowie Carboxymethyl und Hydroxyethylcellulose wurden unterschiedliche Cellulosephosphate hergestellt und mittels 13C‐NMR‐Spektroskopie untersucht. Die Phosphatgruppen wurden in das Cellulosematerial durch trockene Erwärmung mit einer Mischung von Phosphorsäure und Harnstoff eingeführt. Bei allen nach diesem Verfahren erhaltenen Proben wurde eine bevorzugte Substitution der C‐6‐Stellung gefunden.
Theoretical analysis of the processes of heat exchange and relaxation of a polymer melt at the formation of highly oriented polymer films
Authors: Karpov E. A. , Elyashevich G. K. , Neelov I. M. , Ro E. A.
Published: April 2003

A mathematical model is proposed to describe the processes of cooling and relaxation of an oriented polymer melt on a tempering surface. On the basis of this model an algorithm is established that makes it possible to calculate the temperature distribution in the melt from the given external parameters and characteristics of the material. With the aid of of this algorithm the rate of melt cooling at tempering is evaluated. The relationship between the tempering time and the degree of relaxation of macromolecules under predetermined conditions was established.
Transformations of poly(methacrylonitrile) in solutions at the addition of alkali
Authors: Rumynskaya I. G. , Romanova E. P. , Agranova S. A. , Frenkel S. Ya.
Published: April 2003

The kinetics of changes of electronic spectra of poly(methacrylonitrile) in DMSO on addition of alkali was studied. The spectral picture depends on the amount of alkali corresponding to one chain unit, the amount of water in the solution, and the alkali/water ratio. Besides, the maximal attainable effective length of conjugation of cyclic sequences is all the more the lower is the rate of initiation of cyclization. A slow and unsubstantial decrease of the intrinsic viscosity excludes the occurrence of a sharp coil‐globule transition on alkaline hydrolysis of poly(methacrylonitrile).
Melting of oligo(ethylene terephthalate)‐oligo(oxyethylene) block copolymers
Authors: Bogdanov B. , Mihailov M. , Gavrailova G. , Panev Pl.
Published: April 2003

Results obtained by calorimetric investigations on heating of oligo(ethylene terephthalate) (OETP) and oligo(oxyethylene) (OOE) block copolymers with different contents of the components are presented. The temperatures and enthalpies of melting of the crystalline phases, which are formed by the OETP and OOE blocks, are determined. An additional endothermic peak is observed on the DSC curves in a temperature range depending on the molecular weight of the OOE blocks and on the thermal prehistory of the samples. It is supposed that this transition is due to structural changes of the OETP‐OOE block copolymers on heating.
Bestimmung des Gleichgewichtswassergehaltes von Polycaprolactam
Authors: Schmalz E.‐O.
Published: April 2003

Anhand bekannter Gleichungen wird die Rolle des Gleichgewichtswassergehaltes beim Spinnprozeß von Polycaprolactam abgeleitet und ein isochores Verfahren zu seiner Bestimmung angegeben. Für die isobare Verfahrensführung wird eine Gleichung abgeleitet, mit der sich der mittlere Polymerisationsgrad als Funktion des Wasserdampfpartialdruckes und der Kettenreglerkonzentration berechnen läßt. Die Gültigkeit dieser Gleichung wird experimentell überprüft und ein Verfahren zur isobaren Bestimmung des Gleichgewichtswassergehaltes mitgeteilt. Die Unterschiede zwischen einer isochoren und einer isobaren Reaktionsführung werden anhand experimenteller Ergebnisse diskutiert.
Seeded emulsion polymerization of butyl acrylate
Authors: Capek I.
Published: April 2003

The emulsion polymerization of butyl acrylate initiated by ammonium peroxodisulfate in the presence of poly(ethyl acrylate) seed particles was kinetically investigated. The dependence of the final particle number on the initiator concentration deviates from the predictions of emulsion polymerization. The rate of polymerization decreases with increasing monomer concentration. The polymerization behaviour was explained by the polymerization in both the monomer‐swollen emulsifier micelles and the monomer‐swollen polymer particles.
Graft polymerization of acrylamide onto cellulose acetate initiated by ceric ion
Authors: Egboh S. H. O. , Akonwu L. N.
Published: April 2003

The ceric ion method has been used to graft copolymerize acrylamide onto cellulose acetate. The effects of different reaction conditions on the graft yields were investigated. The activation energy and the order of reaction with respect to monomer and initiator concentration have been determined.
Passive isomers of the active center as its possible dormant states responsible for the retardation of propagation of the macroanion of poly(α‐methylstyren)
Authors: Ye. Eizner Yu. , Ushakova I. L.
Published: April 2003

Quantum chemical calculation shows that apart from the formation of the canonical active center in the reaction of a macroanion with a monomer of α‐methylstyrene the formation of isomers of the active center is also possible. These noncanonical isomers seem to be passive in respect to addition of the next monomer molecule. Some other sequences of the calculation which can be checked experimentally are given.
Synthesis and characterization of some N‐vinyl carbazole containing copolymers
Authors: Curteanu S. , Simionescu C. I. , Talmaciu V.
Published: April 2003

The copolymerization of N‐vinyl carbazole with methyl methacrylate and styrene, respectively, was studied. 1H‐NMR spectra and elemental analysis were used to establish the composition of the copolymers. The composition data confirmed that solution radical copolymerization follows quite well the simple terminal copolymerization model.
Structure and properties of chitosan carboxymethyl ether
Authors: Vikhoreva G. A. , Gladyshev D. Y. , Bazt M. R. , Kuznetsova S. Y. , Gal'Braikh L. S. , Lavut E. E. , Ovsepyan A. M. , Panov V. P.
Published: April 2003

Physical, physicochemical and chemical methods were applied to the study of structure, fractional composition, and properties of carboxymethyl chitosan, a polyampholyte containing carboxyl and amino groups. As a result of the interaction of ionogenic groups in the carboxymethyl chitosan their dissociation degrees increase against the corresponding values in chitosan and carboxymethyl cellulose, which are polyelectrolytes containing only one type of functional groups. The viscosity properties of dilute solutions of carboxymethyl chitosan suggest to the polyampholytic nature of the substituted polysaccharide and to the intra‐salt formation in the pH range 2.5 to 7.5, where the ionization regions of opposite charged ionogenic groups overlap to a great extent.
Neuere Ergebnisse zur Isolierung, Modifizierung und Anwendung von Xylanen (Literaturbericht)
Authors: Stscherbina D. , Philipp B.
Published: April 2003

Es wird ein Überblick über die seit Anfang der 70er Jahre erschienenen Arbeiten zu Isolierung und Strukturaufklärung von Xylanen aus Hölzern und Einjahrespflanzen, ihre chemische Modifizierung einschließlich Abbau sowie die Anwendung von Xylanen und ihren Derivaten gegeben.
A new method for the determination of the chemical composition of poly(ethylene terephthalate‐co‐p‐oxybenzoate)
Authors: Vinklárek Z. , Krejčí J. , Vondruška M. , Klásek A.
Published: April 2003

A new analytical method for the determination of the chemical composition of poly(ethylene terephthalate‐co‐p‐oxybenzoate) is described. The method is based on a acid hydrolysis of the polyester sample, subsequent separation of terephthalic and p‐hydroxybenzoic acids of different solubility, and UV spectrophotometric determination of both acids.
Synergetic effect of tinorganic‐tertiary amine catalytic systems in polyaddition reactions of 2, 4‐tolylene diisocyanate with macrodiols
Authors: Sojecki R.
Published: April 2003

The influence of a catalytic system of a tinorganic compound and tertiary amine on the polyaddition reaction of 2,4‐tolylene diisocyanate with macrodiols was investigated. The reaction rate constants were calculated. The magnitude of the synergetic effect in dependence on the composition of the catalytic system was evaluated. When a large excess of the tertiary amine is present in the catalytic system a decrease of the magnitude of the synergetic effect is observed.
Synthese, Aufbau und Eigenschaften von Poly(phthalidyliden‐1,4‐phenylen‐oxy‐1,4‐phenylen) und seiner Nitro‐, Halogen‐ und Cyan‐Derivate
Authors: Solotuchin M. G. , Šitikov A. V. , Sedova E. A. , Kraikin V. A. , Sultanova V. S. , Salaskin S. N.
Published: April 2003

Die Synthese von Poly(phthalidyliden‐1,4‐phenylen‐oxy‐1,4‐phenylen) (I) in Gegenwart von Friedel‐Crafts‐Katalysatoren wird untersucht. Der Einfluß der Synthesebedingungen auf den Aufbau und die Eingenschaften des Polymers wird diskutiert. Durch Nitrierung und unkatalysierte Halogenierung von 1 wurden nitro‐(1a), chlor‐(1b) und bromsubstituierte (1c) Derivate hergestellt. Durch Reaktion von 1c mit CuCN wurden cyansubstituierte Polymere (1d) synthetisiert. Ausgewählte Eingenschaften der Polymere wurden untersucht.
Kinetics of xanthogenation after high‐temperature mercerization
Authors: Pavlov P. , Valtcheva E. , Makaztchieva V. , Lozanov E.
Published: April 2003

With the increase of the mercerization temperature of the cellulose in the process of viscose production from 20 to 105°C, the quality of the obtained viscose goes through a minimum at 70°C, while 105°C is the most advantageous temperature. The kinetics of the xanthogenation after mercerization at the three indicated temperatures has been investigated. It is established that the kinetic characteristics of the xanthogenation are improved in the same order of temperatures of the preliminary mercerization. This shows that the advantageous effect of the high‐temperature mercerization on the quality of the viscose is in direct connection with the favourable effect of the mercerization on the xanthogenation.
Electrical conduction in pure and doped poly(acrylamide) films
Authors: Rao V. V. R. Narasimha , Rao B. Subba
Published: April 2003

The steady state electrical conduction in solution grown poly(acrylamide) films was investigated in the temperature range 303 to 450 K at different field strengths. It was found that the Richardson‐Schottky and Poole‐Frenkel mechanisms operate simultaneously. In films doped with cosin and rhodamine B, respectively, the electrical conduction was attributed to the formation of charge transfer complexes.
Formation of latex particles during the continuous emulsion polymerization of vinyl chloride
Authors: Boieshan V. , Levitschi D.
Published: April 2003

The dispersion degree of latex particles during the continuous emulsion polymerization of vinyl chloride depends on the emulsifier concentration in the system. The particle sizes of the latex vary around average values in connection with the surface area which can be covered with emulsifier in a state of maximum packing.
Morphometrische Untersuchungen an asymmetrischen Celluloseacetatmembranen
Authors: Hirte R. , Rosin Ch. , Philipp B.
Published: April 2003

Die Porenstruktur asymmetrischer Cellulose‐2,5‐acetat‐Membranen wurde mittels elektronenmikroskopischer Aufnahmen der Oberflächenabdrücke von Schnitten senkrecht zur Membranebene charakterisiert. Unter der Voraussetzung kugelförmiger Poren und einer logarithmischen Normalverteilung der Porengrößen gelangen Aussagen über den der trennaktiven Randschicht unmittelbar benachbarten Bereich der Membran.
Pyroelectric currents in undoped and Fe‐doped polystyrene films
Authors: Sharma A. K. , Sagar D. S.
Published: April 2003

The pyroelectric behaviour of undoped and Fe3+ doped polystyrene films was studied at different polarizing fields, polarizing temperatures, and doping concentrations. The pyroelectric currents were positive throughout and showed a significant increase with increasing dopant concentration, polarizing field and temperature. The origin of pyroelectricity has been attributed to space charge polarization.
Monomers in polymer dispersions. III. Diffusion of monomers in poly(vinyl acetate) films
Authors: Hörnig K. , Hemmelmann K. , Brandt H. , Hergeth W.‐D. , Wartewig S.
Published: April 2003

The diffusion coefficients of monomers (vinyl acetate, styrene) within poly(vinyl acetate) films were measured by means of infrared attenuated total reflection spectroscopy and gravimetry. The diffusion coefficients obtained by the two methods are almost identical. This is interpreted as an indication that the molecular processes of diffusion of small molecules in bulk and in surface layer regions of the polymer take place in a similar manner.
Die Rolle der Endgruppen bei der Herstellung, Verarbeitung und Reibung von graphitgefüllten Poly(phenylchinoxalin)en
Authors: Pavlova S.‐S. A. , Timofeeva G. I. , Gribova I. A. , Gureeva G. I. , Krongauz E. S. , Belomoina N. M. , Lendneva N. P. , Stoljarova E. V. , Potapova E. G. , Anochin V. V. , Rubach H. , Falk B.
Published: April 2003

Mittels Sedimentation, Viskosimetrie und Massenpektrometrie wurde der Einfluß der Endgruppen auf die Eigenschaften von Polymerkompositionen auf der Basis von Poly(phenylchinoxalin)en (PPC) und Graphit untersucht. Die Synthese von PPC führt bei nichtäquimolarem Verhältnis der Ausgangskomponenten ohne Füllstoff zu linearen Makromolekülen mit breiter Molmassenverteilung. Auch der Zusatz des Füllstoffs bewirkt weder Verzweigung der Makromoleküle noch Vernetzung und Propfung der Polymerketten auf die Graphitoberfläche. Die Untersuchung der tribochemischen Eigenschaften der komposite zeigt, daß die mit Aminogruppen terminierten PPC im Vergleich zu mit Carbonylgruppen terminierten eine höhere Verschleißestigkeit und einen niedrigeren Reibungskoeffizienten aufweisen. Die besten Werte liefern PPC‐Komposite, die mit einem Überschuß an Tetramin synthetisiert und deren Aminoendgruppen durch Reaktion mit Benzil verkappt wurden.
Chemometrische Bearbeitung von Ausschlußchromatogrammen im niedermolekularen Bereich
Authors: Mikolajczyk L. , Metzner K. , Häusler K. G.
Published: April 2003

Chemometrische Methoden der Chromatogrammbearbeitung gewinnen für die Ausschlußchromatographie im niedermolekularen Bereich an Bedeutung. In der Arbeit werden Verfahren zur Verbesserung der Auflösung (Peaktrennung), zur Erhöhung des Signal/Rausch‐Verhältnisses (Filterung und Akkumulation) sowie zur Peakerkennung diskutiert. Die hohe Leistungsfähigkeit dieser Methoden wird für die qualitative Analyse von Styren‐Acrylnitril‐Cooligomeren mit M < 500g/mol gezeigt.
Chemical modification of acrylonitrile‐butadiene copolymers. I. Characterization and thermal investigations
Authors: Ramesh S. , Rajalingam P. , Radhakrishnan G.
Published: April 2003

An acrylonitrile‐butadiene copolymer was subjected to various chemical modifications. The products were characterized by infrared spectroscopy and gel permeation chromatography. The thermal properties were determined by thermogravimetric analysis. The modified polymers have two to three stages of transition, while the original copolymer exhibits only one transition. In some cases degradation of the polymers was observed.
Preparation and characterization of moulded shapes from Egyptian corncobs‐bisphenol polycondensate resins and aluminium powder
Authors: Sayyah S. M. , Sabry A. I. , Sabbah I. A. , Metwally N. E.
Published: April 2003

Different types of moulded shapes were prepared from Egyptian corncobs‐bisphenol polycondensate resins and aluminium powder. Modifications of the produced resin with phenol‐formaldehyde, naphthalene‐formaldehyde, and anthracene‐formaldehyde, were performed. The electrical conductivity of the samples increases with the increase of temperature and aluminium concent. All samples reveal semiconducting behaviour.
Morphological investigations of mesogenic polyesters
Authors: Minkova L. , Mihailov M. , Jedlinski Z.
Published: April 2003

Two types of main chain mesogenic polyesters were studied by means of polarization microscopy. The morphology of supermolecular structures of as‐obtained polyesters is established. The mesophase textures of the polyesters remain when these are cooled to room temperature. When the polyesters are solved in an appropriate solvent with high concentration, they form optical anisotropic phases. An assumption has been made about the structure organization of crystal phases and of mesomorphous domains at elevated temperature and in solid state after cooling.
Untersuchungen zum thermischen Abbauverhalten von Methylmethacrylat‐Methacrylsäure‐Copolymeren
Authors: Wäsche M. , Kunze R. , Pfeiffer K. , Gnauck R.
Published: April 2003

Die Erhöhung der Strahlenempfindlichkeit von polymeren Resistmaterialien ist für den Einsatz in der Mikroelektronik von großem Interesse. Am Beispiel der thermischen Vorbehandlung von Methylmethacrylat‐Methacrylsäure‐Copolymeren in einer Acetophenon‐Lösung wird gezeigt, daß unter Abspaltung von Wasser und Methanol eine intramolekulare Bildung von cyclischen Anhydridgruppen erfolgt, die bevorzugt durch ionisierende Strahlung gespalten werden. Das thermische Abbauverhalten und die Bestimmung des Anhydridgehaltes werden durch kombinierten Einsatz von TG, MTA, TL und NMR untersucht.
Contribution to covulcanization of elastomers and plastics
Authors: Sain M. M. , Oravec J. , Sain E. , Beniska J.
Published: April 2003

Blends of natural rubber with different types of polyolefins and blends of nitrile rubber with poly(vinyl chloride) have been vulcanized by different vulcanizing systems and at various vulcanizing conditions. The mechanical and thermooxidative properties of the products are tested and compared with each other. On base of the results the vulcanization mechanism is discussed.
Cylinders having rough surface of nanometer size in blend like spherical polymer particles
Authors: Pekcan Ö.
Published: April 2003

The method of direct energy transfer was used to study the internal morphology of colloid particles prepared by nonaqueous dispersion polymerization. The particles contained 97 mole‐% poly(methyl methacrylate) and 3 mole‐% poly(isobutylene). Phenanthrene and anthracene were used as donor and acceptor. The results were interpreted in terms of a cross‐over phenomenon in restricted geometries. A new scheme of the morphology is suggested for the colloid particles.
On the polycondensation of maleic anhydride and poly(ethylene glycol)s
Authors: Nichifor M. , Chitanu G. , Carpov A.
Published: April 2003

The polycondensation of maleic anhydride with poly(ethylene glycol)s of different molecular weights has been examined. At the used reaction conditions the occurrence of some secondary reactions such as polyglycol depolymerization and the addition of glycols to double bonds in the polyesters was established. The possible chemical structure of the obtained unsaturated polyesters is proposed.
Zur übermolekularen Struktur von nativen und isolierten Cellulosen
Authors: Ioelovitch M.
Published: April 2003

Kristallinitätsgrad, Kristallitgröße und Gitterstörungen von nativen und isolierten Cellulosen wurden röntgenographisch ermittelt. Der Kristallinitätsgrad und die Kristallitlänge der nativen Cellulose von Graspflanzen sind niedriger als die von Holz, Flachs und Baumwolle. Die lateralen Kristallitabmessungen der nativen Cellulosen von Graspflanzen und Holz betragen 3,5 bis 4,0 nm, die von Flachs und Baumwollinters 5 bis 7 nm. Bei der Celluloseisolierung durch verschiedene Aufschlußverfahren tritt eine lateral Aggregation der benachbarten Mikrokristallite auf, wodurch die einheitlichen Elementarfibrilen der nativen Cellulose zu Fibrillarbändern zusammengelagert werden.
Besonderheiten der Strukturbildung bei der Koagulation von Polymermischungslösungen. 3. Mitt.: Polymer(A)/Copolymer(AB)/Lösungsmittel‐Systeme
Authors: Albrecht W. , Malsch G. , Weigel Th. , Klug P. , Makschin W. , Gröbe V.
Published: April 2003

Bei der Koagulation von phasenbildenden, unverträglichen Polymermischungslösungssystemen entstehen hochporöse Fällungsstrukturen. Das maximal realisierbare Porenvolumen derart hergestellter Formkörper wird im wesentlichen durch das Volumen der dispergierten Zusatzpolymerlösungsphase in der Polymermischungslösung bestimmt. Wie am Beispiel des Polymermischungslösungssystems PAN/SAN/DMF gezeigt wird, gilt dieses Strukturbildungsprinzip auch im allgemeinen Mischungssystem Polymer(A)/Copolymer(AB)/Lösungsmittel, wenn sowohl die Solvatationsverhältnisse in der Mischungslösung als auch Veränderungen im Verträglichkeitsverhalten berücksichtigt werden.
Zur Verknüpfung von Siloxanen mit Epoxidharzen. 3
Authors: Schickert P. , Rühlmann K.
Published: April 2003

Das Aushärtungsverhalten von quarzgutgefüllten Me‐Ph‐Silicon‐Phenolnovolak‐Epoxidharz‐Formmassen wurde mit Hilfe von Brabender‐Messungen untersucht. Als Katalysatoren wurden Al(acac)3 und Al(benzoat)3 eingesetzt. Das Bindemittel‐Mischungsverhältnis wurde von 60 bis 20% Siliconharz und 40 bis 80% Epoxidharz variiert. Mit dem weniger aktiven Al(benzoat)3 als Katalysator ließen sich technologisch akzeptable Verarbeitbarkeitsdauern tv bei genügender Vernetzungsdichte garantieren. Im Bereich von 40 bis 30% Siliconharz und 60 bis 70% Epoxidharz blieben die Aktivierungsenergien EA gleich. Die EA‐Werte für die Füllstoff enthaltenden Formmassen liegen zwischen 50 und 52 kJ·mol−1 und damit deutlich höher als die Werte für die füllstofffreien Bindemittel, die zu etwa 30 kJ·mol−1 gefunden wurden. Der Gang der EA‐Werte in Abhängigkeit von der Bindemittelzusammensetzung ist jedoch unabhängig vom Füllstoffgehalt. Daraus wird geschlossen, daß die Polymeraufbaureaktionen nur unwesentlich vom Füllstoff beeinflußt werden. Die Ergebnisse zeigen, daß die methodisch einfachen Gelzeit‐ und DSC‐Messungen nicht nur zur Bewertung von Bindemitteln sondern darüber hinaus auch zur Auswahl von Formmassen genutzt werden können.
Thermophysical properties of composite materials on the base of low pressure polyethylene and colloid graphite
Authors: Baranovskij V. M. , Ponomarenko A. T. , Khomik A. A. , Shevchenko V. G. , Kestelman V. N.
Published: April 2003

The results of an investigation of structural and thermophysical properties of polymer composite materials made of low pressure polyethylene and colloid graphite by means of different technological processes are presented. On the base of the obtained results the possibility of prediction and regulation of the thermophysical properties of the studied materials is discussed.
Die charakterisierung der porosität von polyacrylnitril‐faserstoffen im gelzustand
Authors: Grosse I. , Häußler L. , Jacobasch H.‐J. , Schmidt B. , Irlbacher G.
Published: April 2003

Die zur Charakterisierung von Porenstrukturen anwendbaren Meßmethoden Differential‐Scanning‐Calorimetrie, Tieftemperatur‐Gasadsorption, Quecksilber‐Hochdruckporosimetrie, Elektronen‐ und Lichtmikroskopie, Röntgenkleinwinkelstreuung sowie Wasserrückhaltevermögen und scheinbare Dichte werden unter Berücksichtigung der Besonderheiten von Polyacrylnitrilfasern vorgestellt. Die genannten Methoden wurden auf unterschiedlich gereckte und thermisch behandelte PAN‐Fasern im Gelzustand und nach Entwässerung angewendet. Die dabei auftretenden Effekte werden mit der unterschiedlichen Stabilität der Gelfaserstruktur erklärt.
Besonderheiten der strukturbildung bei der koagulation von polymermischungslösungen. 4. mitt.: Membranen aus phasenbildenden, unverträglichen polymermischungslösungen
Authors: Albrecht W. , Klug P. , Makschin W. , Weigel Th. , Gensrich H.‐J. , Gröbe V. , Paul D.
Published: April 2003

Bei der Koagulation von phasenbildenden, unverträglichen Polymermischungslösungen entstehen durch das Zusatzpolymer bedingte, bemerkenswert hochporöse Fällungsstrukturen. Die dargestellten Untersuchungen haben das Ziel, einen möglichen Einfluß der Zusatzpolymere auf die Porosität der Fällungsprimärschicht zu erfassen. Anhand von Permeationsuntersuchungen konnte an den auf fester Unterlage hergestellten Flachmembranen im Gegensatz zur Hohlmembran eine erhöhte Porosität der Fällungsprimärschicht nachgewiesen werden. Hierfür wird ein Porenbildungsmechanismus vorgeschlagen.
Dielectric properties of poly(vinyl formal) films
Authors: Das N. Narsing , Dasaradhudu Y. , Rao V. V. R. Narasimha
Published: April 2003

Poly(vinyl formal) films have been grown from solution. The dielectric properties of the films have been studied in the frequency range 100 Hz to 1 MHz at temperatures from 300 K to 450 K. The plots tan δ versus temperature show two relaxation peaks which are discussed in terms of the molecular structure.
Application of rheological models for the description of the flow characteristics of some polymer systems
Authors: Lungu M. , Petrovan S. , Rusu M. , Apetroaiei A. , Lungu A.
Published: April 2003

The parameters of a generalized rheological model for the description of the flow characteristics of some fluid polymeric systems are determined. Nonlinear regression analysis is used for the fitting of the experimental viscosimetric data. The behaviour of the investigated polymer melts, suspensions and solutions obeys the general equation \documentclass{article}\pagestyle{empty}\begin{document}$ \sigma ^{1/n} = \sigma _o^{1/n} + (\mu \dot \gamma )^{1/m} $\end{document}, where n, σo, μ and m are parameters which characterize the different types of flow behaviour.
Metallic derivatives of cellulose
Authors: Pašteka M.
Published: April 2003

Sodium cellulosate with degree of alkalization 0.59 was used as intermediate for the preparation of silver cellulosate with degree of metallization 0.430, mercury(II) cellulosate with degree of metallization 0.386 and ferric cellulosate with degree of metallization 0.190. Three times repeated alkalization and subsequent metallization yielded ferric cellulosate with degree of metallization 0.589. The metallic cellulosates are stable in water and in aqueous alkaline solutions. In the acidic range of pH from 6 to 4 the stability of the bonds of metallic atoms to the glucose units of cellulose decreased with pH value of the solutions as was established by treating ferric cellulosate with buffered aqueous solutions.
Kinetics of the thermal degradation of polypropylene fibres
Authors: Gambiroža‐Jukić M. , Čunko R.
Published: April 2003

The kinetics of the thermal decomposition of polypropylene fibres has been investigated on the basis of determining the TGA and DTGA curves at various heating‐up speeds in the temperature range from 100 to 600°C. The activation energy E as a kinetic parameter of the decomposition has been defined by means of the Flynn‐Wall and Freeman‐Carroll methods, respectively. It has been established that the activation energy necessarily grows with growth of the conversion level.
Micro‐FTIR studies on cellulose nitrate fibres of different degrees of substitution
Authors: Ludwig M. , Fengel D.
Published: April 2003

Cellulose nitrate fibres of different degrees of substitution were analyzed by micro‐FTIR technique. A suspension of the fibres in Nujol resulted in improved recording conditions. An approach to quantification of the degree of substitution was reached by applying a deconvolution function to the absorbance range of the OH valency vibrations. The relative band height at 3500 to 3535 cm−1was found to be a measure of the nitration degree of cellulose fibres. The influences of the original cellulose as well as the kind of nitration and pretreatment on the spectra of individual fibres were studied.
Characterization and determination of surface charge density of a polymer latex
Authors: El‐Hakim A. A. Abd
Published: April 2003

Potentiometric and conductometric titrations were carried out to get information on the surface charge density of styrenebutyl acrylate copolymer latex. It was established that there are two types of acidic groups present in the polymer latex particles. The effect of electrolyte concentration on the stability of the latex was studied. The values of the critical coagulation constant for the polymer latex have been investigated.
Study of the electric properties of cellulose derivatives
Authors: Marianiová D. , Lapčik L.' , Pisárčik M.
Published: April 2003

The temperature and frequency dependences of electric conductivity of hydroxyethylcellulose, carboxymethylcellulose, 2.5 cellulose acetate, and cellulose triacetate have been investigated in the temperature range from 20°C to 150°C and in the frequency range from 0.5 to 100 kHz. The studies are completed by DTA measurements. The glass transition temperature and the values of the activation energies have been determined and discussed with respect of the structure of the cellulose derivatives.
Polyanion‐polycation interactions in concentrated aqueous systems 1th comm.: Interactions between poly(ethylene imine) and poly(acrylic acid) in dependence on polymer concentration
Authors: Kötz J. , Kosmella S. , Ebert A.
Published: April 2003

Polyanion‐polycation interactions between the free base poly(ethylene imine) and poly(acrylic acid, sodium salt) were investigated in dependence on polymer concentration of the components. At very low polymer concentration between 0.003% and 0.15% we observed a small range of phase separation, because of predominantly non‐Coulombic interactions, determined by using a method combination, consisting of potentiometry, conductometry and turbidimetry. By increasing the polymer concentration no phenomena of phase separation could be observed but a significant viscosity increase above the level of the components in dependence on the molar ratio of cationic to anionic functional groups as well as the molecular weight of the components. The results of NMR spectroscopic investigations in combination with density measurements are discussed with regard to a model of interaction at high concentrations.
Physical properties of poly‐D(—)(3‐hydroxybutyrate)/poly(epichlorohydrin) blends
Authors: Tsukada M. , Romanò M. , Seves A.
Published: April 2003

Physical properties of a new polymer blend obtained by mixing poly‐D(—)(3‐hydroxybutyrate) (PHB), a crystalline polymer with interesting properties of biodegradability and biocompatibility, with uncrystallizable atactic poly(epichlorohydrin) (PECH) were studied. PHB/PECH blends, obtained by casting solution, were analysed by thermomechanical and X‐ray analysis, viscoelastic measurements, and on the basis of strength and elongation measurements. It was concluded that the crystalline region of PHB plays an important role of crosslinks, and amorphous PECH filled between the crystalline regions plays a role of plasticizer. A single dynamic loss modulus, corresponding to the glass transition temperature, implies the miscibility between crystalline PHB and amorphous PECH.
Separation properties and surface morphology of polyacrylonitrile membranes
Authors: Paul D. , Kamusewitz H. , Hicke H.‐G. , Buschatz H.
Published: April 2003

The formation of polyacrylonitrile membranes by phase inversion has been studied. The surface morphology, as investigated by atomic force microscopy, and the separation performance in ultrafiltration were correlated with the concentration of the polymer in the casting solution and a post‐treatment by annealing.
Determination of domain sizes in heterogeneous polymers by solid‐state NMR
Authors: Clauss J. , Schmidt‐Rohr K. , Spiess H. W.
Published: April 2003

Advanced solid‐state NMR techniques exploiting 1H spin diffusion are described, which rely on selecting 1H magnetization of one of the components on the basis of 1H chemical shift or mobility differences under multiple‐pulse irradiation. To monitor the progression of 1H spin diffusion, the higher resolution of 13C CP MAS spectra is exploited for NMR detection. For evaluation of the data, full quasi‐analytical solutions of the diffusion equation as well as initial‐rate approximations are derived, applied and discussed. In order to obtain quantitative results, the 1H spin‐diffusion constant has to be determined. To this end, the domain sizes in poly(styrene)‐poly(methyl methacrylate) systems including symmetrical diblock copolymers have been measured. The comparison of the NMR results with SAXS and TEM data yields the spin‐diffusion coefficient for PS and PMMA. The resulting value of D=0.8 nm2/ms is expected to be typical for rigid organic systems. The domain sizes investigated range from approximately 1 nm to ca. 100 nm.
A Diels‐Alder ladder polymer bridged by imino and ether groups
Authors: Löffler M. , Schlüter A.‐D. , Enkelmann V.
Published: April 2003

The synthesis of a Diels‐Alder ladder polymer with imino and ether bridges is described. The structure proof is based upon a comparison of its high resolution 13C‐NMR spectrum with those of model compounds. The molecular weights can reach values as high as M̄n = 52000 which are the highest ones observed so far for a double stranded polymer. The X‐ray structure of model compound 8 is also presented.
Detection of ferroelectric to paraelectric phase transition in copolymers of vinylidene fluoride by magnetic susceptibility
Authors: Flores A. , Ania F. , Cabarcos E. López , Calleja F. J. Baltá
Published: April 2003

The diamagnetic susceptibility of a series of random copolymers of vinylidene fluoride (VF2) with trifluoroethylene containing 60 to 100 mole‐% VF2 has been investigated, both as a function of composition and of temperature. Results show that at room temperature the molecular susceptibility of the series linearly decreases with VF2 content. Furthermore, the diamagnetic susceptibility for each composition rises gradually at the beginning of the Curie transition, reaching a plateau which characterizes the diamagnetism of the paraelectric phase. The percent increase in diamagnetism when passing from the ferroelectric to the paraelectric phase is primarily due to the changes occurring from the planar all‐trans polar conformation into the disordered molecular conformation of the high temperature phase. The reduced final increase in diamagnetism detected at the melting point suggests that conformational transformations occurring from the paraelectric phase into the molten state are small.
The influence of hydroxyethylcellulose on the diffusion of acetylsalicylic acid trihydromagnesium salt in aqueous solution
Authors: Pisárčik M. , Mikula M. , Marianiová D. , Lapčik L'.
Published: April 2003

The mean mutual diffusion coefficient of acetylsalicylic acid trihydromagnesium salt in water and in hydroxyethylcellulose aqueous solution is studied using optical refractometric Philpott Svensson method. It was found that the presence of the polymer increases the diffusion coefficient of the magnesium salt in the three‐component system. The self‐diffusion coefficient of hydroxyethylcellulose aqueous solution with and without addition of the magnesium salt was also measured using dynamic light scattering. The possible diffusion mechanism of the magnesium salt in aqueous solution with presence of the polymer is explained. Assuming the experimental data of the two‐component system with respect to the addition of a third component, it was found that the jumping distance of magnesium salt increases approximately linearly with the hydroxyethylcellulose concentration.
Thermal stability of poly(2‐acrylamido‐2‐methylpropanesulphonic acid) and polymer complexes of 2‐acrylamido‐2‐methylpropanesulphonic acid with some transition metal salts
Authors: Aggour Y. A.
Published: April 2003

Poly(2‐acrylamido‐2‐methylpropanesulphonic acid) and polymer complexes of 2‐acrylamido‐2‐methylpropanesulphonic acid with nickel(II), copper(II), iron(III) chlorides and cobalt (II) sulphate, respectively, were prepared and characterized by spectroscopic techniques. Thermal stability of the formed polymer complexes was determined by means of thermogravimetric analysis. It was found that the thermal stability of the homopolymer is less than that of the polymer complexes. The activation energies of the degradation of the polymer complexes were determined by using the Arrhenius equation.
Investigations about dissolution of cellulose in the LiCl/N,N‐dimethylformamide system
Authors: Morgenstern B. , Berger W.
Published: April 2003

Using various cellulose samples, the conditions of cellulose dissolution in N,N‐dimethylformamide with added lithium chloride were established. The way of activation of cellulose influences decisively the dissolution. Complete dissolution of microcrystalline cellulose can only be achieved after treating with liquid ammonia. The required salt concentration amounts to approximately 10 wt‐%. Degree of polymerization and crystallinity of the cellulose influence significantly the solubility behaviour.
Biodegradable polymers. 7th comm. On the mechanism of ring‐opening polymerization of cyclic esters of aliphatic hydroxycarboxylic acids by means of different tin compounds
Authors: Dahlmann J. , Rafler G.
Published: April 2003

To elucidate the effect of tin compounds in the ring‐opening polymerization of lactides and lactones, D,L‐dilactide was taken as an example, and its reaction with different tin compounds at a molar ratio of 1:1 as well as the polymer formation and degradation in dependence of its concentration has been investigated. Two entirely different reaction courses were observed which are consequently influenced by compounds with alcoholic and/or carboxylic OH groups in different ways.