bluuebunny/crossref_metadata_2025 huggingface dataset:
Starch size in loomstate cotton fabric accelerates grafting of methacrylic acid induced by KMnO4/citric acid system
Authors: El Sisi F. , Hafiz S. A. Abdel , El Rafie M. H. , Hebeish A.
Published: April 2003

The use of loomstate cotton fabric (starch sized fabric) as a substrate for grafting of methacrylic acid using KMnO4/citric acid as initiator provided an effective method with greater potentiality. Presence of starch size on the fabric helps the deposition of MnO2 over the fabric with subsequent acceleration of the grafting reaction. Major factors affecting polymerization of MAA, such as KMnO4, citric acid and MAA concentrations, as well as reaction time and temperature of polymerization were studied. A tentative mechanism for the polymerization reaction is suggested.
Biologisch abbaubare polymere. 1. Mitt. Viskositäts‐molmassen‐beziehung für poly‐d,l‐lactid und poly(glycolid(50)‐co‐lactid(50))
Authors: Rafler G. , Dahlmann J. , Wiener K.
Published: April 2003

Durch Ringöffnungspolymerisation hergestellte Poly‐D,L‐lactide wurden durch Viskosimetrie, Osmometrie, Streulichtphotometrie, Gelchromatographie und Endgruppenbestimmung umfassend charakterisiert. Auf der Grundlage membranosmometrisch ermittelter M̄n‐Werte wurden die Viskositäts‐Molmassen‐Beziehungen für Polylactid in Chloroform und Dimethylformamid sowie für ein äquimolar zusammengesetztes Lactid‐Glycolid‐Copolymer in Dimethylformamid bestimmt. Für Polylactid wurde das M̄w/M̄n‐Verhältnis zu ca. 2 bestimmt.
Photooxidation retardants. II. Spectra‐structure correlations of new additives from 3‐oxo‐3‐phenyl‐N‐(2‐pyridyl)propanamide for use as photooxidation retardants in polymers
Authors: Hanna M. A. , Girges M. M.
Published: April 2003

The synthesis of 3‐oxo‐3‐phenyl‐N‐(2‐pyridyl)propanamide and twelve of its arylhydrazone derivatives for use as additives to resist photooxidation in polymers is described. The structure of these compounds is dominated by the presence of double hydrogen bonding. Intramolecular charge transfer occurs through the nonbonding electrons on the amino nitrogen atom of the hydrazone moiety as donor rather than through the amide group, and the benzoyl carbonyl group as acceptor. The mode of action of these products as UV absorbers is discussed.
Mechanism of deformation at large strains in semicrystalline polymers‐LDPE
Authors: Mayer J. , Schrodi W. , Heise B. , Kilian H. G.
Published: April 2003

Crystallinity, mean crystal thickness, thickness distribution of crystal, and mean thickness of the amorphous layers in LDPE are deduced by treating it as a eutectoid copolymer. This knowledge is transferred into a van der Waals network theory which includes plastic shear deformation of crystals. The fit of stress‐strain pattern at different temperatures and of temperature induced relaxation and shrinkage informs about the deformation mechanism in semicrystalline polymers.
Poly(oxyethylen)‐poly(oxypropylen)‐poly(oxyethylen)‐triblockcopolymere. Struktur und dynamik
Authors: Wartewig S. , Alig I. , Bloss P. , Hergeth W.‐D. , Lange J. , Lochmann J. R. , Scherzer T.
Published: April 2003

Das Löslichkeitsverhalten und die physikalische Natur des Trübungspunktes eines POE‐POP‐POE‐Triblockcopolymers in wäßriger Lösung werden mit verschiedenen experimentellen Methoden (Viskosimetrie, Grenzflächenspannungsund Dichtemessungen, Ultraschallgeschwindigkeits‐ und ‐absorptionsmessungen, statische und dynamische Lichtstreuung, Infrarot‐ und Ramanspektroskopie, DSC‐Messungen) untersucht. Die Hydratisierung der Moleküle und die Dimensionen der Molekülassoziate werden diskutiert. Experimentelle Befunde belegen, daß der Trübungseffekt mit kritischen Erscheinungen verbunden ist. Der Vergleich der spektroskopischen Ergebnisse mit Konformationsenergierechnungen zeigt, daß Konformationsübergänge das Verhalten am Trübungspunkt bestimmen.
Optical studies of chain orientation by thermal treatment and mechanical stretching of Teflon PFA foil
Authors: Kułek J. , Kroupa J.
Published: April 2003

The effect of thermal treatment and uniaxial stretching on the temperature dependence of optical birefringence, degree of crystallinity, thermally stimulated depolarization, and isothermal discharge of electrets obtained of Teflon PFA foil has been studied. The increase in stability of charge is related to changes in the polymer structure.
Dynamic mechanical anisotropy of undrawn polypropylene films
Authors: Sadiku E. R.
Published: April 2003

Undrawn isotactic polypropylene films were studied for dynamic anisotropy. The rations of the loss moduli and of the loss tangent in the parallel and perpendicular directions, respectively, gave a better picture of the anisotropy effect than the ratio of the storage moduli. In both the loss moduli and loss tangent ratios a very sharp γ‐transition was observed at‐60°C. Two γ‐transitions at 15 and 60°C, respectively, which are not very strongly marked in the tests in the individual directions, showed up fairly sharp in the anisotropic parameters used for the characterization. A weak γ‐transition was observed in both test directions. The results are discussed with respect t o anisotropy of crystal imperfection and stability.
Einfluß der Temperung auf die Eigenschaften von modifizierten Polymeren
Authors: Kardanov Ch. K. , Ivanovskij V. A. , Ch. Kardanov A. , Zelenev Ju. V.
Published: April 2003

Der Einfluß der Temperung auf die änderung der Eigenschaften von Polymeren wird mit Hilfe der Relaxationsspektrometrie untersucht. Als neuartige Untersuchungsmethode wird die Messung der elektrischen Fluktuationen bei Temperaturänderungen angewandt. Die Messungen wurden an Poly(methylmethacrylat) durchgeführt.
Water‐insoluble polyelectrolytes. 1. Polyampholytes by aminolysis of poly(acrylonitrile) with dicyandiamide
Authors: Gohlke U. , Dautzenberg H.
Published: April 2003

By aminolysis of poly(acrylonitrile) with dicyandiamide and a subsequent reaction with hydroxylamine, polyampholytes are formed, which exhibit different ranges of insolubility around the isoelectric point. The reason for the improved solubility of the twice modified polymer is its higher concentration of dissociable functional groups. The aggregation behaviour of the polyampholyte is discussed on base of the intrinsic viscosities measured in dependence on the pH value.
Athermische und thermische Keimbildung bei sphärolithischer Kristallisation
Authors: Dobbert P. , Fabry F.
Published: April 2003

Anhand von Modellrechnungen wird gezeigt, wie sich athermische und thermische Keimbildung auf den zeitlichen Verlauf der Hauptkristallisation von Polymeren auswirken, wenn unterschiedliche Sphärolithmodelle zugrunde gelegt werden. Die Überlegungen machen deutlich, daß die aus Meßkurven α(t) zu ermittelnden Parameter Keimdichte, Sphärolithform und radiale Wachstumsgeschwindigkeit komplex über die Kristallisationszeit miteinander verknüpft sind. Eindeutige Aussagen über diese Größen sind deshalb nur in Sonderfällen oder durch Einbeziehung weiterer Informationen über die Kristallisationskinetik möglich.
Thermomechanical properties and chemical resistance of alkyl methacrylate‐N‐vinyl carbazole copolymers
Authors: Ryttel A.
Published: April 2003

Copolymers of ethyl methacrylate and n‐butyl methacrylate with N‐vinyl carbazole were synthesized by bulk polymerization. The thermal stability, softerning point, chemical resistance, glass transition temperature, hardness, density, and shrinkage on polymerization of the copolymers were studied. The effect of N‐vinyl carbazolel content on the properties is discussed.
Zur Synthese von Polysilanen
Authors: Heinicke J. , Uhlig W. , Tzschach A. , Reinhold G.
Published: April 2003

Der Einfluß der Reaktionsbedingungen und des Lösungsmittels auf die Molmassenverteilung von Polysilanen, hergestellt durch Umsetzung von Diorganodichlorsilanen mit Natrium, wurde untersucht. Einsatz von Paraffinöl als Solvens verkürzt die Reaktionszeten und liefert, wie für (MePhSi)n näher studiert, auch in Mischungen höhermolekulare Produkte. Die beobachteten Effekte lassen sich durch im wesentlichen diffusionskontrollierte Oberflächenreaktionen an Natrium erklärren.
Plasmaätzen dünner Schichten organischer Polymere. Teil III: Zum phänomenologischen Mechanismus des Schichtabtrags
Authors: Eggert L. , Friedrich J. , Wittrich H. , von Löwis M. , Abraham W.
Published: April 2003

Zwei unterschiedliche Vorstellungen zum Ablauf des Abtrags von Polymerschichten in einem nichtisothermen Sauerstoffplasma einer elektrischen Hochfrequenzentladung werden diskutiert: der successive Abbau an der Oberfläche und die plasmaphysikalische Verfestigung der Polymeroberfläche bei gleichzeitiger Verlagerung des Abbaus in des Polymervolumen. Das letztgenannte Modell von Valiev verlangt komplizierte Diffusionsprozesse von abbaufähigen Plasmaspezies und entsprechenden Abbauprodukten. Die hier durchgeführten Modellversuche sprechen in ihren Ergebnissen gegen das Modell von Valiey, wobei jedoch die plasmamodifizierte Polymeroberflächenschicht tatsächlich eine besondere Rolle beim Abbau der gesamten Polymerschicht spielt.
High‐active Ziegler‐Natta catalysts on polymeric supports for the manufacture of injection moulding polyethylene
Authors: Mix H. , Fuhrmann H. , Reihsig J. , Bredereck H. , Oswald L. , Pracht H. , Häupke K.
Published: April 2003

Polymeric supports on the base of linear and crosslinked polystyrenes have been used in this work for the immobilization of Ti‐Mg Ziegler‐Natta complexes. The resulting catalysts are tested in the homopolymerization of ethylene in a suspension process at 358 K and a total pressure of 0.84 MPa. By use of hydrogen for molecular weight control, injection moulding polyethylene in good yield is obtained. Influences of support parameters on a catalytic activity, melt flow index, and bulk density are studied.
Trimethyl(maleimidophenyl)ammonium iodides and their copolymers
Authors: Lokaj J. , Bleha M. , Bílá J.
Published: April 2003

New quaternary ammonium monomers derived from N‐(dimethylaminophenyl)‐maleimides were prepared and characterized. Their copolymerization with vinyl compounds and modification of the polymers of the starting imides with methyl iodides yielded copolymers containing trimethyl(maleimidophenyl)ammonium units. Membranes based on crosslinked imide copolymers were prepared, and their properties were determined after quaternization of the tertiary amino groups.
Structure and physicomechanical properties of high density polyethylene filled during polymerization
Authors: Minkova L. , Velikova M. , Damyanov D.
Published: April 2003

The morphology of supermolecular structures in polymerization filled polyethylene prepared with the TiCl4/(C2H5)2AlCl catalyst system and chalk and marble powder as fillers has been investigated. It is established that the lamellar crystallites envelop the filler particles, the bases of the lamellae being parallel to the filler surface. Up to the investigated filling degree (21.7 to 23.5 wt%), the formed supermolecular structures affect favourably the physicomechanical properties of the polymer filled during polymerization. A mechanism of the formation of the structures is proposed.
Zur Synthese und Verarbeitbarkeit von Polymeren mit halbstarren Ketten
Authors: Berger W. , Kammer H. W. , Litauszki L.
Published: April 2003

Es wird über die Synthese von Polyimiden mit aliphatischen Seitenketten berichtet. Einige Eingenschaften dieser Materialien werden angegeben. Der Einfluß der Kettensteifheit auf die Verarbeitung von Polymeren zu hochmoduligen und hochfesten Materialien wird diskutiert.
Synthese von Siloxan‐Thioether‐Copolymeren
Authors: Klemm E. , Beil U. , Märtin R.
Published: April 2003

Durch Photoaddition von Divinylsiloxan 1 und Bismercaptoethyldisiloxan 2 entstehen Thioether‐Disiloxan‐Copolymere, deren Struktur eindeutig durch 13C‐NMR und Elementaranalyse bestimmt ist. Bei nichtäquivalentem Molverhältnis (r = 0,5) wird aus Divinylsiloxan und 1,8‐Dimercapto‐3,6‐dioxaoctan ein SH‐terminiertes Telechel erhalten, das mit dem Divinylsiloxan hochmolekulare (Mn = 17000) Polythioether nit Siloxanstruktureinheiten in der Polymerhauptkette ergibt.
Zum Mechanismus der Elektronenstrahlvernetzung von 1,4‐cis‐Polybutadien
Authors: Häusler K. G. , Hobisch G. , Hummel K. , Stoll G. , Reinhold G. , Wartewig S.
Published: April 2003

Pyrolysegaschromatographische Untersuchungen von mit β‐Strahlen vernetztem 1,4‐cis‐Polybutadien ergaben eine bis zu zehnfach größere Abnahme der Spaltprodukte 1,4‐Butadien und 4‐Vinylcyclohexen als sie nach Ablauf eines bisher angenommenen Reaktionsmechanismus und den Ergebnissen der Kompressionsmodulmessungen auftreten dürfte. Diese drastische Verringerung der Hauptspaltprodukte kann nur auf eine entsprechend große Abnahme der Doppelbindungen im Polybutadien mit zunehmender Vernetzung zurückgeführt werden. Durch Metatheseabbau in Kombination mit einer GC/MS‐Kopplung und ramanspektroskopische Untersuchungen konnte gezeigt werden, daß der Abbaugrad und die CC‐Doppelbindungen in gleicher Weise mit zunchmender Strahlendosis und Netzwerkdichte abnehmen. Die strahlenchemische Vernetzung von 1,4‐cis‐Polybutadien erfolgt damit über die Aufspaltung der Doppelbindungen mit einer sich anschließenden Kurzkettenpolymerisation und führt zur Bildung von Netzknoten mit einer Funktionalität f > 10.
Peculiarities of the thermomechanical behaviour of polybutadiene‐poly(butadiene‐co‐styrene) blends
Authors: Todorova I. , Bechev Ch. , Tenchev Ch.
Published: April 2003

The thermomechanical behaviour of some polybutadiene‐poly(butadiene‐co‐styrene) blends has been investigated. A method for the prognostication of glass transition temperature of the blends based on the data of thermomechanical analysis is proposed.
A yield criterion for glassy polymers subjected to long‐lasting loads
Authors: Witemberg‐Perzyk D.
Published: April 2003

A simple failure criterion for polymers subjected to creep at constant load is proposed. The criterion applies to the shear type of yielding of hard polymers in glassy state and permits the calculation of time‐to‐yield at arbitrary state of stress. The proposed equation has been successfully verified experimentally with semitransparent poly(vinyl chloride).
New bis(naphthalic anhydride)s with organoelement central groupings and poly(naphthaoylene benzimidazole)s on their basis
Authors: Bulycheva E. G. , Prigozhina M. P. , Ponomarev I. I. , Butskhrikide B. A. , Tsiskarishvili R. P. , Rusanov A. L. , Vinogradova S. V. , Jedlinski Z. , Palivoda A.
Published: April 2003

New bis(naphthalic anhydride)s with organoelement diphenylsilyl and m‐carboranyl groups have been obtained by interaction of acenaphthene dichloroanhydrides of the respective dicarboxylic acids in Friedel‐Crafts reaction followed by oxidation of the bis(acenaphthyl)s and anhydridization of the synthesized tetracarboxylic acids. Interaction of the anhydrides and bis(‐o‐phyenylenediamine)s yielded poly(naphthoylene benzimidazole)s, which combine good thermal characteristics with solubility in organic solvents and possess thermosetting properties.
Polycondensation of bis(diethylamino)dimethylsilane with phenylenediamines
Authors: Kulpiński J. , Lasocki Z.
Published: April 2003

Polycondensation of bis(diethylamino)dimethylsilane with p‐ and m‐phenylenediamines with elimination of diethylamine in each elementary step gives cyclic oligomers with high yields. Heating of those at temperatures above 400°C results in the formation of crosslinked polymeric material. With o‐phenylenediamine, biomolecular cyclization yields diazadimethylsilaindane, which undergoes further rearrangements. Structural investigations of all the oligomeric products are reported.
Some physicochemical properties of biocompatible and biodegradable heterochain polymers based on L‐lysine
Authors: Katsarava R. D. , Kharadze D. P. , Toidze P. L. , Omiadze T. N. , Japaridze N. N. , Pirtskhalava M. K.
Published: April 2003

Some heterochain polyureas and polyamides based on L‐lysine have been synthesized in different media. The effect of the reaction conditions on the microstructure and the properties of the obtained polymers is discussed.
Zur „Äquilibrierung”︁ von Octamethyl‐cyclotetrasiloxan mit 1,3‐Divinyl‐disiloxan
Authors: Nyárádi Cs. , Zimonyi E. , Nagy J.
Published: April 2003

Die durch Alkalihydroxid beschleunigte Äquilibrierung von Octamethyl‐cyclotetrasiloxan mit 1,3‐Divinyltetramethyldisiloxan wird untersucht. Der zeitliche Ablauf der Äquilibrierung wird durch Viskositätsmessungeii verfolgt. Der Zusammenhang zwischen Viskosität des Endproduktes und dem Molverhältnis der Ausgangsprodukte wird mathematisch dargestellt.
Über die Struktur und Umordnungsvorgänge in der amorphen Phase des Poly(vinylchlorid)s
Authors: Schulze G. , Donth E. , Behrens H.
Published: April 2003

In der amorphen Phase des PVC bestehen zwischen benachbarten Kettensegmenten Richtungskorrelationen, die unter dem Einfluß von Weichmachern weitgehend aufgehoben werden. Bei Extraktion des Weichmachers mit n‐Heptan stellen sich diese Richtungskorrelationen im Gegensatz zur Extraktion mit Ether zunächst nicht wieder ein. Die Folge der Extraktion mit n‐Heptan ist eine extrem niedrige Dichte des PVC von 1,24 g · cm−3. Messungen der spezifischen Wärme an solchen Proben zeigen kurz unterhalb Tg einen extrem starken Peak, der mit Schmelzpeaks einer kristallinen Phase vergleichbar ist. Die Diffusion und Extraktion des Weichmachers und der Einfluß nachträglicher Temperung wurden mit Hilfe der Röntgenkleinwinkelstreuung verfolgt. Messungen der spezifischen Wärme, der Röntgenweitwinkelstreuung und elektronenmikroskopische Untersuchungen bestätigen die Vorstellungen.
Fast calculation of the time dependent dielectric permittivity for the Havriliak‐Negami function
Authors: Schönhals A.
Published: April 2003

A convenient and quick procedure for numerical inverse Laplace transformation of the HAVRILIAK‐NEGAMI model function is presented.
Zum Mechanismus der Verstärkung von 1,4‐cis‐Polybutadien mit Ruß
Authors: Häusler K. G. , Heinrich G. , Schikowski M. , Straube E. , Stepto R. F. T.
Published: April 2003

Das Spannungs‐Dehnungs‐Verhalten einer Serie von vulkanisierten Proben mit Polybutadien als Kautschukkomponente und Schwefel als Vernetzungsagens wurde in Abwesenheit und Gegenwart unterschiedlicher Gehalte an Ruß untersucht. Dabei wurden eindeutige Korrelationen zwischen dem Gehalt an Ruß und der gemessenen Verstärkung gefunden. Diese Abhängigkeit läßt sich am besten mit einem Netzwerkmdell beschreiben, das von Phantomketten ausgeht, die über die konventionellen chemischen Vernetzungsstellen (Schwefelbrüchen zwischen den Primärmolekülen) und zusätzlich chemisch über hochdisperse multifunktionelle, räumlich ausgedehnte Füllstoffdomänen verknüpft sind. Das Konzept der weitestgehend nur physikalischen Verstärkung bei derartigen Kautschukmischungen auch nach der Vernetzung ist damit neu zu überdenken.
Synthesis and evaluation of 4‐acetyl‐3‐hydroxyphenyl methacrylate – a useful polymerizable UV stabilizer
Authors: Li Shanjun , Qin Anwet , Zhang Hanmin , Chen Jingmin , Vogl O.
Published: April 2003

A new polymerizable ultraviolet stabilizer, 4‐acetyl‐3‐hydroxyphenyl methacrylate (AHPM), was synthesized and characterized. It was copolymerized with styrene in different molar ratios to provide a new UV absorbing and stabilizing system. The ultraviolet spectra of AHPM and its copolymers were determined. The fluorescence spectra of AHPM and its copolymers with styrene at different ratios were also investigated. The efficiency of AHPM as an ultraviolet stabilizer was examined by studying the change of the inherent viscosity of the copolymer during the exposure of the polymer to UV irradiation.
Homo‐ und Copolymerisation von Butadien und Isopren mit Ni/Ti/Al‐ und Ni/B/Al‐Katalysatorsystemen. v. isoprenhomopolymerisation und blockcopolymerisation butadien/isopren mit einem ni/b/al‐katalysator in n‐heptan
Authors: Gebauer U. , Oberdörfer A. , Gehrke K.
Published: April 2003

In Vorbereitung der Blockcopolymerisation Butadien/Isopren mit dem Katalysatorsystem Nioct./BF3 · Et2O/AlEt3 wurde die Isoprenhomopolymerisation mit diesem Katalysator in n‐Heptan untersucht. Durch Variation der Polymerisationszeit, der Monomer‐ und Katalysatorkonzentration konnte das allgemeine Geschwindigkeitsgesetz formuliert werden. Die Blockcopolymerisation ergab überwiegend Butadien‐Butadien‐Verknüpfungen. Die Diblockcopolymerisation mit höheren Werten für den Umsatz und die Molmasse erscheint effektiver im Vergleich zur Triblockpolymerisation Butadien/Isopren/Butadien.
Plasmaätzen dünner Schichten organischer Polymere. Teil VIII. Zum Plasmaätzen von Poly(vinylalkohol)
Authors: Eggert L. , Abraham W.
Published: April 2003

Frühere Hypothesen über einige Besonderheiten des Ätzens von Poly(vinylalkohol) (PVAL) im Sauerstoffplasma wurden bestätigt. Erstens wird beim O2‐RIE von Poly(vinylalkohol) im Unterschied zum Plasmaätzmodus kein Abfall der Ätzgeschwindigkeit mit steigendem Schichtabtrag beobachtet. Zweitens ist die Aktivierungsenergie beim Plasmaätzen von Poly(vinylbutyral) im Unterschied zum PVAL unabhängig vom Schichtabtrag. Diese experimentellen Ergebnisse sowie einige Literaturangaben bestätigen, daß sich auf PVAL‐Schichten im Sauerstoffplasma eine dicke „K‐Schicht”︁ bildet. Im Polymervolumen ablaufende Degradationsprozesse unter dieser „K‐Schicht”︁ sind hauptsächlich für den Abbau dünner Schichten aus PVAL im Sauerstoffplasma verantwortlich.
Thermal stability of polyurethanes with allophanate and isocyanurate crosslinks
Authors: Kościelecka A.
Published: April 2003

Polyurethanes prepared by reaction of 4,4′‐diphenylmethane diisocyanate with poly(ethylene adipate) were crosslinked with allophanate and isocyanurate groups. Their thermal properties were studied by isothermal and nonisothermal thermogravimetry. It has been found that there is no correlation between the initial decomposition temperature and the concentration of crosslinks. The rate of mass loss decreases with crosslinking density for polyurethanes crosslinked with more than 50 mole‐% excess of diisocyanate.
Thermooxidative Beständigkeit von plastifiziertem, mit erbium‐Diphthalocyanin modifiziertem Poly(vinylchlorid)
Authors: Venediktov E. A. , Možžuchin V. V. , Bornmann U. , Beresin B. D.
Published: April 2003

Mittels Thermogravimetrie im Luftsauerstoffstrom wurde der Einfluß von Er3+‐Diphthalocyanin auf die thermooxidative Beständigkeit von plastifiziertem Poly(vinylchlorid) untersucht. Das mit Erbium‐Diphthalocyanin modifizierte Polymer weist eine höhre Thermostabilität als das Ausgangspolymer auf. Die stabilisierende Wirkung von Er3+‐Diphthalocyanin wurde mit der von industriellen Co2+‐ und Cu2+‐Phthalocyaninen sowie von Metallporphyrinen verglichen.
Neuartige Mittel zum Ausflocken
Authors: Domasch K. , Wittig F.
Published: April 2003

Wasserlösliche polymere Flockungsmittel werden erfolgreich zur Verbesserung von fest/flüssig‐Trennprozessen eingesetzt. Nachteile dieser Produkte, wie unerwünschte Restgehalte, können durch die Verwendung neuartiger, wasserunlöslicher Mittel zum Ausflocken reduziert werden. In Laborversuchen haben sich bisher als wirksamste Substanzen kationisch oberflächenmodifizierte Glasfasern erwiesen. An Modellsystemen wird in Abhängigkeit von verschiedenen Versuchsparametern ein deutlicher Flockungseffekt nachgewiesen.
Solution properties of ultrahigh molecular weight polymers. 17. Conformational transitions of poly(isobutyl methacrylate) in dilute solution
Authors: Ioan S. , Flondor A. , Simionescu B. C. , Simionescu C. I.
Published: April 2003

The temperature dependence of viscosity of ultrahigh molecular weight poly(isobutyl methacrylate) fractions in dilute solution has been investigated. A discontinuity of intrinsic viscosity was observed in the temperature range 20 to 30°C. The study of unperturbed dimensions and polymer‐solvent interaction parameters shows that both inter‐ and intramolecular interactions are affected. This effect modifies the flexibility of the macromolecular chain and other properties in solution.
Copolymerizations of acrylonitrile with cobalt and nickel acrylate. Formal kinetics equations
Authors: Czerniawski T. , Wojtczak Z.
Published: April 2003

On the basis of the factorial method of experiment design the radical copolymerizations of acrylonitrile with cobalt and nickel acrylate in dimethylformamide solution have been studied. The values of the constants of the copolymerization rate equations are similar in both investigated systems.
The influence of the spinning rate on the structure and mechanical properties of PETP fibres
Authors: Militký J. , Vaníček J.
Published: April 2003

The influence of spinning speed and velocity of cooling air on the structural and mechanical parameters of PETP fibres is investigated by correlation and regression analysis. By means of derivative analysis, characteristic points on the stress‐strain curves are identified. The results are compared with previous works and discussed on base of simple hypotheses.
Determination of the crystallinity of cellulose samples by x‐ray diffraction
Authors: Majdanac L. D. , Poleti D. , Teodorovic M. J.
Published: April 2003

Changes in the fine structure of cellulose samples of different origin during treatment with sodium hydroxide in ethanol/water mixtures were studied. A computer program was written for peak separation and profile analysis. The presence of an amorphous phase was taken into account by adding a Gaussian type function to the diffraction profile. This method gives very good agreement parameters and enables the precise estimation of the crystallinity of cellulose samples. The relations between total and partial crystallinties, crystallite dimensions, and crystallite cross‐sections are discussed.
Disorder effects in the crystal structure of form II of poly(vinylidene fluoride)
Authors: Kutschabsky L. , Höhne E. , Kretschmer R.‐G.
Published: April 2003

A new model based on disorder phenomenon concerning the symmetry is proposed for the crystalline structure of form II of poly(vinylidene fluoride) (PVDF). The disorder has the effect that the crystal possesses no unique space group but it consists alternately of monoclinic regions with space group P21/c and orthorhombic regions with space group Pbc21. The ratio between monoclinic and orthorhombic parts changes depending on the conditions of sample preparation. This model explains all experimental data published in literature. Theoretical calculations confirm the correctness of the new model.
Dynamics of polyethylene melts as studied by nuclear magnetic relaxation including effects of inner field‐inhomogeneities
Authors: Geschke D. , Fleischer G.
Published: April 2003

The nonexponential decay of the transverse magnetization as typical for high molar mass polyethylene melts is studied by means of different pulse sequences and the MAS technique. The interpretation of the experimental results is based on the known model of COHEN‐ADDAD but in addition the influence of internal field gradients is discussed which also contributes to the signal attenuation.
Bicomponent membranes. IV. Influence of membrane formation principles on the structure of the active layer of membranes
Authors: Weigel Th. , Makschin W. , Albrecht W. , Gröbe V. , Paul D.
Published: April 2003

Polyacrylonitrile membranes are prepared using three different membrane preparation principles. Characterization of the structure of the skin layer is carried out in more detail by parameters of separation curves and their pore size distribution function, the former being based on a logarithmic normal distribution. Under constant conditions of measurement, comparing considerations are reflected about the structure of the separating active layer of PAN bicomponent membranes and two differently prepared PAN monocomponent membranes. The parameters of the separation curves and pore size distributions are discussed.
Untersuchungen zum thermischen Verhalten von phenolharzgebundenen Cellulosepapier‐Schichtpreßstoffen. 2. Der Einfluß der Verbundbildung auf das thermische und das Brandverhalten
Authors: Goetzky P. , Gnauck Regine
Published: April 2003

Der Masseverlust von phenolharzgebundenen Cellulosepapier‐Schichtpreßstoffen bei der dynamischen Thermoanalyse (DTA) ist über einen weiten Temperaturbereich geringer als die Summe der Masseverluste der Komponenten. Der bei 850°C verbleibende Koksrückstand korreliert mit dem Sauerstoffindex. Das Verhalten der Laminate bei der DTA wird durch phosphor‐ und stickstoffhaltige flammwidrige Zusätze merklich beeinflußt, durch bromhaltige nur geringfügig.
Synthesis and characterization of stationary phases on the basis of silicas modified with epoxidized polybutadienes. Synthesis and characterization of a new polyhydroxy functionalized stationary phase for high performance liquid chromatography
Authors: Erler U. , Spange S. , Heublein G.
Published: April 2003

A new polyhydroxy functionalized support, derived from reaction composites of epoxidized polybutadienes and silicas, is tested as a stationary phase for high performance liquid chromatography. As demonstrated in various chromatographic separations, the retention behaviour of different test solutes depends on their polarity and hydrogen bond forming ability. A number of phenolic compounds, xanthine derivatives, and steroid samples is chromatographed under isocratic conditions with hexane, methanol and THF as eluents.
Emulsion polymerization of vinyl acetate by using potassium persulfate‐iron tetraoxalyl urea as redox initiation system
Authors: Badran A. S. , Yehia A. A. , Shendy S. M. M. , Moustafa A. B.
Published: April 2003

The kinetics and mechanism of emulsion polymerization of vinyl acetate using the redox initiation system potassium persulfate‐iron tetraoxalyl urea in presence of the emulsifiers poly(vinyl alcohol) and sodium lauryl sulfate, respectively, were investigated. The effect of different reaction conditions on the rate of polymerization and on the molecular weight of the obtained poly(vinyl acetate) was studied. It was found that the mentioned initiation system increases the maximum conversion and forms a stable emulsion at low temperatures.
Polymerization by phase transfer catalysis. 12. Poly(ether‐ester)s from (2,2‐bis(1,4‐phenyleneoxy)‐propylidene)‐diacetic acid and related diacids with diphenols
Authors: Tagle L. H. , Diaz F. R. , Vargas M. A.
Published: April 2003

Poly(ether‐ester)s from (2,2‐bis(1,4‐phenyleneoxy)‐propylidene)‐diacetic acid and related diacids with diphenols were synthesized using several ammonium and phosphonium salts as phase transfer catalysts. The best results were obtained with benzyltriethylammonium chloride, which is a hydrophilie catalyst that not promotes hydrolysis of the polymeric chains. Other onium salts also were effective as phase transfer catalysts. Polymers were characterized by IR and 1H‐NMR spectroscopy and elemental analysis. Molecular weights were estimated by inherent viscosity measurements.
Kinetic treatment of termination processes at radical polymerizations
Authors: Timpe H.‐J. , Kronfeld K.‐P.
Published: April 2003

By means of a general formulation, kinetic equations have been derived, which describe the participation of additional processes on the termination of radical polymerization reactions. These expressions can be used for termination reactions with primary radicals, too. By this way, using only one pair of experimental data for the polymerization rate and the corresponding polymerization degree, and by known k/kt ratio, the ratio of rate constants of primary radical termination and polymerization reaction, and also the content of end groups derived from initiator fragments can be calculated. The usefulness of the developed equations was verified with photopolymer systems consisting of aromatic ketone/methyl methacrylate and diisopropoxy thiocarbonyl disulfide/methyl methylacrylate mixtures. The calculated values agree well with those obtained with other equations given in the literature. Contrary to other procedures, the new method possesses advantages due to the smaller amount of experimental data necessary.
Dielectric measurements in an amorphous polymer — poly(methyl methacrylate)
Authors: Narula G. K. , Pillai P. K. C.
Published: April 2003

Dielectric parameters have been measured with poly(methyl methacrylate) films in the frequency range 100 Hz to 1 MHz and the temperature range 60°C to 140°C. The dielectric loss spectrum at 60°C exhibits two peaks corresponding to the α and the β relaxations of the polymer. At higher temperatures a single loss peak is observed. The dielectric loss spectrum at different temperatures is normalized for different loss peaks. It is suggested that at low frequencies and high temperatures polarization of the trapped charge carriers gives rise to dielectric losses.
Zum Formfaktor polymerer Netzwerke mit partieller Steifigkeit der Netzketten
Authors: Heinrich G. , Beckert W.
Published: April 2003

Die Streufunktionen underformierter und deformierter Polymernetzwerke aus Netzketten mit Steifigkeit werden im Rahmen des Papadopoulos‐Thomchick‐Modells berechnet. Es zeigt sich, daß für große Wellenzahlen der Kratky‐Plot des PT‐Modells nicht in das für Gaußketten typische Plateau einmündet, sondern eine ansteigende Gerade als Asymptote besitzt, deren Anstieg mit wachsender Steifigkeit zunimmt.
Zur thermodynamischen Charakterisierung von Polymer Blends mit der inversen Gas‐Flüssig‐Chromatographie. I. Poly(vinylacetat) + Poly(n‐butylmethacrylat)
Authors: Wohlfarth Ch.
Published: April 2003

Die χ‐Werte von 13 verschiedenen Lösungsmitteln mit Poly(n‐butylmethacrylat) beziehungsweise Poly(vinylacetat) werden über einen Temperaturbereich von 343 bis 423 K beziehungsweise 403 bis 473 K mit der inversen Gas‐Flüssig‐Chromatographie ermittelt. Untersuchungen am 1:1‐Blend beider Polymere ergeben den χBC‐Wert des Polymer‐Polymer‐Systems. Gegenüber einer früheren Arbeit beobachten wir eine deutlich geringere Abhängigkeit der χBC‐Werte von den Lösungsmittelproben.
Semicontinuous emulsion polymerization of vinyl acetate IX. Decomposition of the initiator
Authors: Donescu D. , Fusulan L.
Published: April 2003

The way in which the decomposition reaction of a persulfate initiator is influenced by the nature of reactants of the polymerization medium and by the working conditions during the semicontinuous polymerization and copolymerization of vinyl acetate is studied. The rate of the splitting reaction of potassium persulfate is higher in the aqueous phase containing a protective colloid and surfactant. The splitting rate is smaller in the presence of vinyl acetate. The presence of hydrophobic commonomers decreases the rate of initiator decomposition. An increase of the addition rate of monomers leads to an increase of the obtained polymer and of the splitting rate of the initiator.
Adsorptive surface modification of a manganiferous ore and its effect on the radical polymerization of methyl methacrylate
Authors: Moustafa A. B. , Radwan F. M. , Emam A.
Published: April 2003

The surface unmodified manganiferous ore catalyzed the radical polymerization of methyl methacrylate initiated by sodium bisulphite. An adsorptive surface modification of the ore with stearic acid was carried out to various extents. The influence of the surface coverage on the reaction parameters was investigated. The surface modification effectively retarded the catalytic action of the manganiferous ore and caused a drop of the viscosity average molecular weights of the polymers.
Infrared spectroscopy of oligoethyleneterephthalate‐oligooxyethylene block copolymers
Authors: Bogdanov B. , Mihailov M. , Gavrailova G.
Published: April 2003

The temperature dependence of structure sensitive absorption bands in the infrared spectra of oligoethyleneterephthalate‐oligooxyethylene (OETP‐OOE) block copolymers is investigated. Informations on the crystalline structures formed by the OETP and OOE blocks are obtained. A measurable mutual influence between these structures when crystallizing from solution or from melt has been established.
The phase behavior of polymer blends – Effects of thermodynamics and rheology
Authors: Kammer H. W.
Published: April 2003

Part one of the paper is devoted to the thermodynamics of the phase behaviour of polymer blends. According to an equation‐of‐sate theory the phase behaviour is directed by the interplay of three effects: the interaction between the segments, the free‐volume effect, and the size‐effect. When the size‐effect is negligible only lower critical solution temperature (LCST) behaviour occurs. Phase separation at elevated temperatures is an entropy driven process whereas at an upper critical solution temperature (UCST) an unfavourable enthalpic effect associated with the size‐effect acts as driving force for phase separation. Also positive volumes of mixing can be related to the size‐effect. In the second part the phase behaviour of blends exposed to shear is discussed. For blends it has been found experimentally that shear flow elevates phase‐separation temperatures. Obviously, shear‐induced phase changes depend on the stored elastic excess energy. A negative stored excess energy corresponds to an additional attraction between the different segments, hence, the miscibility region of the system is enlarged theoretical and experimental reuslts agree qualitatively.
Sphärolithwachstum bei der isothermen Kristallisation von Poly(ethylenterephthalat)
Authors: Fabry F. , Dobbert P.
Published: April 2003

Anhand von Messungen zur Zeitabhängigkeit des Kristallinitätsgrades und der Kleinwinkellichtstreuung von kristallisierten Poly(ethylenterephthalat)‐Proben wird ein Auswerteverfahren vorgestellt, das es gestattet, Aussagen zur Sphärolithform und deren Änderung im Verlauf der isothermen Kristallisation zu machen. Ausgehend von einer modifizierten Avrami‐Gleichung läßt sich ein Formparameter berechnen, der die Abweichung von der Kugelgestalt angibt. Die Ergebnisse zeigen, daß sich mit wachsender Kristallisationszeit die Garbenform immer stärker ausprägt, die Kugelform wird jedoch nicht erreicht.
Einfluß der Morphologie bei Polypropylen mit Propylen/Ethylen‐Copolymerisaten auf Tieftemperaturschlagzähigkeit und Weißbruch
Authors: Ramsteiner F.
Published: April 2003

Die reduzierte Schlagzähigkeit von Polypropylen unterhalb dessen Glasübergangstempertur kann durch Einmischen einer dispersen Phase verbessert werden. Mit dieser Zähigkeitsverbesserung geht aber durch die so erhöhte Craze‐Verformung die Bildung von Hohlräumen einher, an denen Licht gestreut wird; der aus optischen Gründen unerwünschte Weißbruch entsteht. Der Einfluß der Größe der dispergierten Teilchen auf die Tieftemperaturzähigkeit und die parallel laufende unerwünschte Neigung zum Weißbruch wird aufgezeigt.
Polyelectrolyte behaviour of poly(vinyl alcohol)‐boric acid complexes
Authors: Moneva‐Andonova L.
Published: April 2003

The polyelectrolyte behaviour of poly(vinyl alcohol)‐boric acid complexes is investigated. A plateau is observed in the dependence of pKa on the degree of neutralization, while the HENDERSON‐HASSELBACH plots show two linear regions with different slope related to two different macroconformations. The complexes undergo a transition to an extended rigid conformation when neutralized in aqueous solution determined by decreased flexibility of the chain and charge acquisition.
Organische Elektronenleiter und Vorstufen. XIII. Untersuchungen zum thermischen Verhalten von Poly(bis‐alkylthio‐acetylen)en
Authors: Richter A. M. , Laube U. , Moniak F. , Fanghänel E. , Hempel G. , Goldenberg S. , Scheler G.
Published: April 2003

Das thermische Verhalten der Poly(bis‐alkylthio‐acetylen)e wurde im Temperaturbereich von 30°C bis 600°C untersucht. Aus den Ergebnissen der thermischen Analyse, aus 13C‐Festkörper‐NMR‐ und ESR‐Messungen an den festen Thermolyserückständen und der Untersuchung der flüchtigen Pyrolyseprodukte werden mögliche Abbaureaktionen abgeleitet. Für einen weiten Zeit‐ und Temperaturbereich wird für Poly(bis‐methylthio‐acetylen) ein einfaches kinetisches Modell formuliert.
Determination of molecular weight of poly(acrylic acid) using ultrasonic technique
Authors: Hassun S. K. , Hussain F. M. A. , Al‐Mehdi H. A. H.
Published: April 2003

Ultrasonic velocity and isentropic compressibility of aqueous solutions of poly(acrylic acid) of various molecular weights and concentrations have been measured. The results are discussed on base of the interactions between polymer and water molecules. An equation correlating the isentropic compressibility and molecular weight of the polymer is suggested.
Solvent‐induced phase separation in ternary solutions of poly(methyl methacrylate), poly(styrene‐co‐acrylonitrile) and toluene
Authors: Reichelt K. , Kummerlöwe C. , Kammer H. W.
Published: April 2003

Morphology evolution in ternary polymer solutions consisting of poly(methyl methacrylate), poly(styrene‐co‐acrylonitrile) having different AN‐contents and toluene was studied by optical microscopy and light scattering. The solutions subjected to different isothermal demixing conditions displayed regularly or irregularly phase separated structures. Effects of the AN‐content of the SAN, the blending ratio and the annealing conditions on the arising morphologies are presented. A criterion for conservation of the periodic bicontinuous structure developed in the unmixing process can be established.
The effects of surfactants on the miscibility of polymers
Authors: Funke Z. , Starke L.
Published: April 2003

The surface tension of molten LDPE can be determined with the help of the pendent drop method, depending on the temperature and on the surfactant added. The critical micelle concentration was reached on addition of 1% of the surfactant. A four‐component mixture consisting of HDPE, LDPE, PVC, and PS, whose composition corresponded to that of collected waste plastics, was used to study the effects of the addition of surfactants on the applicational properties.
The sorption of ethyl xanthogenate on polyester fibres. I. Electrokinetic properties
Authors: Espinosa‐Jiménez M. , Cano Suárez A.
Published: April 2003

An experimental investigation on the streaming potential and adsorption of ethyl xanthogenate ions on polyester fibres at various temperatures has been carried out. The results reveal that the uptake of ethyl xanthogenate ions by the polyester fibres in the tested temperature interval takes place with the establishment of strong chemical bonds. The results are interpreted on the basis of nucleophilic attack of the negatively charged oxygen in the carbonyl group of the polyester on the thiocarbonyl group of the xanthogenate ion.
Ultrasonic investigation of thermostabilized poly(acrylonitrile) fibres
Authors: Lyubcheva M.
Published: April 2003

Thermostabilized poly(acrylonitrile) fibres obtained under different conditions have been investigated by means of ultrasonic measurements. The correlations between ultrasonic velocity, density, and some properties of the fibres are studied. The possibility of using ultrasonic velocity as a parameter for the control of the oxidation process of poly(acrylonitrile) fibres is discussed.
The synergetic effect of the catalytic system di(tributyltin) carbodiimide + triethylene diamine in reactions of 2,4‐tolylene diisocyanate with macrodiols at various temperatures
Authors: Sojecki R.
Published: April 2003

The influence of temperature on the magnitude of the synergetic effect of the catalytic system di(tributyltin)carbodiimide + triethylene diamine in reactions of 2,4‐tolylene diisocyanate with macrodiols has been studied. For calculations of the reaction rate constants a differential‐integral method based on the consequent‐parallel reaction scheme was applied. A proportional increase of the maximal synergetic effect with increase of temperature has been established. A qualitative interpretation of the observation is presented.
Catalytic degradation of polyolefines under the action of friedel‐crafts catalysts in solution. 2. Investigation of structural pecularities of degraded poly(isobutene) by low‐temperature calorimetry and 13C‐NMR
Authors: Khalafov F. R. , Novrusova F. A. , Krentsel B. A. , Agaeva E. A. , Yafarov O. I. , Mekhtiev S. A. , Kuliev A. M. , Nurullaev G. G.
Published: April 2003

The temperature dependence of specific heat of poly(isobutene) degraded under the action of strong Lewis acids has been investigated. From the calculated thermodynamic parameters have been drawn conclusions on the structural conversions of the macromolecules in the process of catalytic degradation. By means of 13C‐NMR the formation of branched macromolecules was shown. On the basis of the results a degradation mechanism for poly(isobutene) is suggested.
Treatment of celluloses in nonaqueous solution of sodium hydroxide
Authors: Pašteka M.
Published: April 2003

Treatment of cellulose with solution of sodium hydroxide in isopropyl alcohol leads to formation of sodium cellulosate, which is destroyed in water medium to the starting substances. The degree of alkalization of the cellulosates depends on the pretreatment of the cellulose materials. It is assumed that the degree of alkalization is connected with the acceptibility of cellulose for sodium hydroxide or sodium isopropylate.
Poly(ethylene terephthalate) fibres with improved mechanical properties
Authors: Evstatiev M. , Sarkisova M. , Petrovich S. , Fakirov S.
Published: April 2003

Cold drawn poly(ethylene terephthalate) (PETP) fibres are subjected to zone annealing or isothermal annealing with fixed ends. The morphological changes taking place during both types of thermal treatment are followed by means of SAXS, WAXS, birefringence and density measurements, DSC, and mechanical tests. Differences in the supermolecular structure of the samples subjected to zone annealing and those annealed with fixed ends are established. Zone annealing results in better definition of the basic structural elements, higher orientation and larger number of taut tie molecules which in turn predetermine the higher performance of the zone annealed material.
Effect of the type of divinyl monomers on the structure and properties of their copolymers with 4‐n‐amyl styrene
Authors: Solovskaya N. A. , Zakharov S. K. , Asinovskaya D. N. , Lukyashina V. A. , Andreev D. N.
Published: April 2003

Copolymers of 4‐n‐amylstyrene with dimethylsilyldiacrylate and diacrylmethylmethane were synthesized. The physicochemical, thermomechanical and elastic properties of the copolymers have been studied. The structure of the divinyl monomer affects the crosslinking and the mechanical properties of the materials.
Concentration dependent diffusion of water in polyamide 6
Authors: Hanspach J. , Pinno F.
Published: April 2003

The dependence of water diffusion in polyamide 6 on water concentration can be described by the equation D(c) = D(0) + βc2. The mean value D̄ correlates with the diffusion coefficient defined by Fick's law and depends exponentially on temperature with the activation energy Es = 0.49 eV. The diffusion process can be described by the thermally activated exchange of water molecules in cooperation with free volume. On the other hand free volume is generated by the water itself which affects the concentration dependence of the diffusion coefficient.
Structural changes of LODP cellulose in the original and mercerized state during enzymatic hydrolysis
Authors: Fink H.‐P. , Philipp B. , Zschunke C. , Hayn M.
Published: April 2003

The structural changes during enzymatic hydrolysis of cellulose substrates were studied by SAXS, WAXS, water retention values, and degree of polymerization. LODP cellulose samples in original (cellulose I) and mercerized (cellulose II) form were hydrolyzed using a commercial cellulase preparation produced by the fungus Trichoderma reesei. The mercerization of the LODP‐cellulose I powder results in a remarkable increase in degradability due to a more finely dispersed void structure with a distinct higher specific inner surface of the cellulose II. Based on the course of the degree of crystallinity, lateral and longitudinal crystallite sizes, and the DP at different stages of degradation a supermolecular mechanism of the “all or nothing” type was found for the chains in LOPD‐cellulose I, whereas for cellulose II an endwise degradation of ordered regions has been concluded.