bluuebunny/crossref_metadata_2025_split huggingface dataset:
Infrared spectroscopic investigations of unpoled poly(vinylidene fluoride) films in an electric field
Authors: Büchtemann A. , Stark W. 
Published: April 2003

AbstractIn poly(vinylidene fluoride) (PVDF) the rotation of the dipoles in an electric field can be followed by the change of the infrared absorption bands at 445 cm−1 and 510 cm−1. Referring to preceding measurements on PVDF foils with evaporated infrared transparent electrodes a stepwise increased field was applied. Following the formerly developed model, the normalized absorptions of both bands were plotted one against the other. A deviation from the expected linear relation in the field dependence of both absorption bands was found. This behaviour is interpreted by an increase of the amount of long trans sequences.
NMR and IR spectroscopic investigations of thermooxidatively treated pan fibres
Authors: Frigge K. , Büchtemann A. , Fink H.‐P. 
Published: April 2003

AbstractDuring thermooxidative treatment of PAN fibres at temperatures between 180 and 320°C several chemical reactions take place. As a result of cyclization by means of N‐bridges and dehydrogenation, connected with the formation of conjugated double bonds, aromatic rings are formed. Furthermore, carbonyl groups occur due to oxidation. The resulting product is insoluble and nonmeltable. Therefore the mentioned reactions as well as the composition of the final product may be investigated by means of only a limited number of methods, among which high‐resolution 13C‐solid state‐NMR and infrared spectroscopy proved to be particularly suitable. The reaction starts at about 180°C, the first being dehydrogenation. Cyclization and oxidation follow as temperature further increases.
Thermally stimulated depolarization currents in poly(acrylamide) films
Authors: Rao V. V. R. Narasimha , Rao B. Subba 
Published: April 2003

AbstractThe charge storage mechanism in poly(acrylamide) films was studied by means of the technique of thermally stimulated depolarization currents (TSDC). The TSDC were measured as a function of field strength, temperature and time of polarization in dependence on the heating rate. One peak was observed on the TSDC spectra at low polarizing temperatures, while two peaks occurred for higher polarizing temperatures. The first peak was attributed to dipole orientation and the second one to space charge polarization.
Untersuchungen zur Polymerisation von Vinylchlorid in Mikrosuspension. Teil 2
Authors: Schirge H. , Schlegel R. 
Published: April 2003

AbstractBei der Mikrosuspensionspolymerisation des Vinylchlorids mit dem Redoxsystem Dilauroylperoxid/Dicetylperoxidicarbonat, Cupfersulfat und Ascorbinsäure wurde der Einfluß der Cu2+‐Ionen auf den Restperoxidgehalt im Polymer und auf die gebildeten Polymere untersucht. Der Mechanismus der Initiierung wird diskutiert.
Crystallization and melting behaviour in block copolymers of poly(ethylene oxide) with amorphous components. The influence of compatibility
Authors: Unger R. , Donth E. 
Published: April 2003

AbstractBy means of DSC, connections between melt crystallization (Tc) and melting temperatures (Tm) of block copolymers have been studied as depending on the compatibility of the block copolymer components. As examples for a compatible and an incompatible system, the systems poly(ethylene oxide) (PEO, crystalline)‐poly(methyl methacrylate) (PMMA, amorphous) and PEO/poly(tert.‐butyl methacrylate) (PTBMA, amorphous), respectively, were used. The compatibility of both systems is described. In block copolymers of compatible components, Tc depends on the composition, but it is less than in comparable blends. Provided a sufficient crystallization time is available, Tm is, in effect, only dependent on the PEO molecular weight. In block copolymers of incompatible components both Tc and Tm were strongly determined by molecular weights of all blocks of both components and, connected with that, by PEO domain sizes. Tc vs. Tm diagrams are presented and discussed.
Liquid crystallinity by poly(acrylate)s and poly(methacrylate)s with stilbene units
Authors: Kossmehl G. , Pithart C. 
Published: April 2003

AbstractThe synthesis and characterization of poly(acrylate)s and poly(methacrylate)s containing 4′‐substituted stilbene‐4‐carboxylic acid side groups attached by flexible spacers containing two, six, or eleven methylene groups are described. Most of the poly(methacrylate)s have nematic phases. In contrast, none of the poly(acrylate)s exhibit liquid crystalline behaviour.
A study of adsorbed polymer using a new centrifugal method
Authors: Strenge K. , Klodt R.‐O. , Bordihn P. 
Published: April 2003

AbstractA simple method is described for the estimation of the pressure‐distance curves for sterically stabilized particles using a laboratory centrifuge. The method can be used to characterize adsorbed macromolecules. As an example the experiments with two different polymers (poly(vinyl alcohol) and methylhydroxypropoxycellulose) and their mixtures at saturation adsorption are reported.
The effect of chemical inhomogeneity on the characteristics of polyelectrolytes based on poly(4‐vinylpyridine)
Authors: Tretyakova A. Ya. , Sagitova N. S. , Barabanov V. P. , Myagchenkov V. A. 
Published: April 2003

AbstractThe influence of chemical inhomogeneity on viscosity, electrical conductivity, and surface characteristics of aqueous solutions of partially quaternized poly(4‐vinylpyridine) is studied. The compositional inhomogeneity of the macromolecules causes a change of the interactions in the polyion‐counterion system in comparison with compositionally homogeneous copolymers.
Contact angle measurements on surface modified cellulose membranes
Authors: Kamusewitz H. , Malsch G. , Paul D. 
Published: April 2003

AbstractThe static contact angle hysteresis on pendant bubbles was measured with pure and surface modified regenerated cellulose and compared with model‐theoretical considerations. The interfacial tensions were calculated by the method of geometrical mean. The experimental results prove that regenerated cellulose is covered by a closed water film, which is ruptured by hydrophobic islands after surface modification.
Polydispersity of regenerated alkali celluloses during oxidative degradation
Authors: Teodorović M. , Dšnhelka J. , Majdanac L. 
Published: April 2003

AbstractThe molecular weight distribution of cellulose samples for viscose preparation, alkalized in various ways, was determined by size exclusion chromatography using diluted cadoxen as the solvent. In this solvent the degraded and extremely unreactive alkalized samples with cellulose II structure were directly soluble. It was found that the distribution curves of the investigated samples gradually become narrower with degradation time, especially when harsher conditions were used (higher temperature, more concentrated NaOH, longer aging time).
Synthesis and characterization of liquid crystalline polysiloxanes with stilbene units
Authors: Kossmehl G. , Pithart C. 
Published: April 2003

AbstractThe synthesis and characterization of polysiloxanes containing 4′‐substituted stilbene‐4‐carboxylic acid side groups attached through flexible spacers containing three, six or eleven methylene groups are described. All polymers exhibit smectic phases. Two of the six synthesized ω‐alkenylstilbenecarboxylates exhibit liquid crystalline behaviour characterized by two smectic phases.
Thermodynamics of cationic polymerization. 3. Examples
Authors: Hallpap P. , Stadermann D. , Bölke M. 
Published: April 2003

AbstractThermodynamic relations of cationic polymerization are reported. According to previously derived estimations, presumptions concerning the ratio r1:r2 for different copolymerization systems are made. Most of them are confirmed by the experiment. Three reasons for the preferred polymerization of isobutene from a C4‐fraction are discussed. Among them is a “repairing mechanism”, which leads to a consumption of the other components in the mixture of not more than 10%. An explanation is given for the increase of the double bond content in the polymer during the end of the copolymerization reaction.
On the ionic polymerization ability of vinyl monomers
Authors: Eizner Yu. E. , Hallpap P. , Bölke M. , Kolzov A. I. 
Published: April 2003

AbstractThe ability of some vinyl monomers to polymerize according to both cationic and anionic mechanisms is investigated using the CNDO/2 and the MINDO/3 methods. Additionally, the influence of solvent was considered. Model calculations of butadiene and other model compounds clearly demonstrate the amphoteric character of the studied monomers. Furthermore, the “diametral‐analogous” behaviour of the compounds comparing cationic and anionic polymerizations is shown. Calculating the interaction betweenSiMe3 containing compounds and different cations and anions, the mobility of the SiMe3 group as one of their characteristic properties can be explained.
Synergetic effect of the catalytic system tri(tributyltin)isocyanate/triethyldiamine in the reaction of 2,4‐tolylene diisocyanate with macrodiols at different temperatures
Authors: Sojecki R. 
Published: April 2003

AbstractThe influence of temperature on the magnitude of synergetic effect of the catalytic system tri(tributyltin)isocyanate + triethyldiamine in the reaction of 2,4‐tolylene diisocyanate with macrodiols has been studied. A proportional increase of the maximal synergetic effect with increase of temperature has been found. A qualitative interpretation of the phenomenon is presented.
Synthese und Eigenschaften halogensubstituierter aromatischer Polyetherketone
Authors: S̆itikov A. V. , Gileva N. G. , Kraikin V. A. , Solotuchin M. G. , Rafikov S. R. , Salaskin S. N. 
Published: April 2003

AbstractChlorierung, Bromierung und lodierung der Polyketone auf der Grundlage von Diphenyloxid und Chloranhydriden der Terephthal‐ und Isophthalsäuren werden untersucht. Aufbau und Einfluß des Typs und des Anteils der Halogene auf die Löslichkeit und die physikalisch‐mechanischen Eigenschaften der Polymere werden analysiert.
Copolymerization of N‐phenyl maleimide with methyl acrylate, ethyl acrylate, methyl methacrylate, and butyl methacrylate
Authors: Mohamed A. A. , Hasan M. E. H. 
Published: April 2003

AbstractN‐phenyl maleimide (NPMI) was copolymerized with methyl acrylate (MA), ethyl acrylate (EA), methyl methacrylate (MMA), and butyl methacrylate (BMA). The composition diagrams for the copolymerization were determined. An azeotropic monomer composition was found in the range 0.55 to 0.65 of the acrylate feed ratio for the systems MA, EA, and MMA with NPMI with a maximum initial rate of copolymerization at 10 mole‐% acrylate, whereas neither an azeotropic composition nor a maximum rate was found with the system BMA‐NPMI. High concentration of maleimide in the monomer feed affects the intrinsic viscosity negatively. Degradative chain transfer to maleimide is assumed to cause the decrease in molecular weight.
Phenacyldimethylsulfonium ylide‐mercuric chloride complex initiated radical polymerization of 4‐vinyl pyridine
Authors: Bhatnagar U. , Srivastava A. K. 
Published: April 2003

AbstractThe polymerization of 4‐vinyl pyridine initiated by phenacyldimethylsulfonium ylide complex of mercuric chloride is investigated. The polymerization reaction is retarded in the presence of hydroquinone and benzene, but accelerated by dimethylformamide. A mechanism for the radical formation is suggested.
Untersuchungen zur Bildung wasserlöslicher Cellulosephosphate durch homogene Acylierung im System Cellulose/N2O4/DMF. 2. Mitt.: Ergebnisse zur Acylierung mit Derivaten des POCl3 und zusamenfassende Diskussion zum Ablauf der Phosphorylierung im System N2O4/DMF/Cellulose
Authors: Wagenknecht W. , Nehls I. , Philipp B. , Schnabelrauch M. , Klemm D. , Hartmann M. 
Published: April 2003

AbstractCellulose und Carboxymethylcellulose wurden nach Auflösung im N2O4/DMF‐System mit modifizierten Phosphorylierungs‐reagentien acyliert, die durch Umsetzung von POCl3 mit Wasser oder mit N2O4 erhalten wurden. Das durch Umsetzung mit N2O4 modifizierte Reagens erwies sich als geeignet zur Gewinnung wasserlöslicher Cellulosephosphate in Form des Natrium‐oder des Triethylammoniumsalzes im DS‐Bereich zwischen 0,2 und 1,3. Ein Reaktionsmechnaismus für die bei Acylierung und Nachbehandlung ablaufenden Umsetzungen wird diskutiert.
Bildungsweise, Struktur und Anwendungsmöglichkeiten von Komplexen zwischen Polyelektrolyten und ionischen Farbstoffen (Literaturübersicht). Teil I: Einführung und Überblick über Komplexe zwischen kationischen Polyelektrolyten und anionischen Farbstoffen
Authors: Dawydoff W. , Linow K.‐J. , Philipp B. 
Published: April 2003

AbstractAnhand der einschlägigen Literatur wird ein Überblick über Bildungsweise und Struktur von Komplexen zwischen kationischen Polyelektrolyten und anionischen Farbstoffen gegeben. Nach einigen Bemerkungen zur experimentellen Methodik wird unter Betonung unterschiedlicher Möglichkeiten der Farbstoff‐Polymer‐Bindung eine nach Polymerklassen gegliederte stoffliche Systematik gegeben, wobei der Schwerpunkt bei den synthetischen Polymeren mit kationischen Gruppen und von Seiten der Farbstoffkomponente bei Methylorange und seinen Homologen liegt.
Dilute solution properties of polyurethane
Authors: Ali S. I. , Ali S. 
Published: April 2003

AbstractLow angle laser light scattering and viscosity studies were made on dilute solution of fractions of polyurethane prepared from butandiol and hexamethylene diisocyanate. The intrinsic viscosities were correlated to molecular weights by the MARK‐HOUWINK‐SAKURADA equation. The values of the constants Km and a have been determined. In spite of the low refractive index increment of polyurethane in benzene, molecular weights as low as 4300 could be measured.
Stromträgerrelaxationen in hochohmigen Polymerfestkörpern
Authors: Neumann W. 
Published: April 2003

AbstractNeben relaxierenden Dipolen können auch Stromträger zeitabhängige Ströme nach Änderung des äußeren elektrischen Feldes bewirken. Als Kriterien dafür werden neben Intensität und Lage des Relaxationsgebietes die nichtlineare Abhängigkeit der gespeicherten Ladung von der äußeren Feldstärke angesehen. In Poly(chinoxalin) und Poly(ethylenterephthalat) werden Stromträgerrelaxationen durch blockierende Kontakte verursacht. Detaillierte Untersuchungen erlauben Aussagen über die Stromträgerdichte im Probenvolumen und Eigenschaften der Kontaktschicht. In Poly(chinoxalin) ist weiterhin Wechselstromhopping nachweisbar.
Block copoly(ether‐ester)s with oligo(1,2‐oxypropylene) soft segments
Authors: Słonecki J. 
Published: April 2003

AbstractRandom thermoplastic block copoly(ether‐ester)s were prepared by polycondensation in the melt. For the synthesis dimethyl terephthalate, butanediol‐1,4, and oxyethylated oligo(1,2‐oxypropylene)diol were used. The copoly(ether‐ester)s obtained contained tetramethylene terephthalate hard blocks and copolyether soft blocks. The copolymers were characterized by viscosimetry in solution, swelling, and determination of carboxyl end groups. The thermal properties were determined by DSC, dynamic mechanical testing, and melting temperature. Hardness and mechanical properties at tension were determined over a wide temperature range. Thermal and mechanical properties were discussed considering the influence of copoly(ether‐ester) composition on chain flexibility and some utility properties.
Polymerization of styrene with N,N′‐bis[(4‐t‐butylazo‐4‐cyano‐valeryl)‐oxyethyl]‐azo‐bis‐formamide
Authors: Simionescu C. I. , Popa A. A. , Comāniţā E. , Manolache S. , Comāniţā B. 
Published: April 2003

AbstractThe solution polymerization of styrene in benzene by using N,N′‐bis[(4‐t‐butylazo‐4‐cyanovaleryl]‐oxyethyl)‐azo‐bis‐formamide as a bifunctional initiator is studied. The reaction was proved to be influenced by some factors, namely, initiator and monomer concentrations, temperature, and duration. To correlate the polymer conversion and its molecular weight with these parameters, two regression equations were obtained by carrying out the experiments according to a centrated, rotatable, second order experimental design.
Infrared spectroscopic study of field‐induced band shifts and dipole orientation in poly(vinylidene fluoride)
Authors: Büchtemann A. , Müller I. , Stark W. 
Published: April 2003

AbstractInfrared spectra of uniaxially drawn ß‐PVDF films under the influence of an electric field were registered. The direction and the strength of the applied field were changed in up to 13 cycles. The field‐induced frequency changes of the bands at 445 cm−1 (CF2‐rocking) and 510 cm−1 (CF2‐bending) were studied in detail. Model calculations concerning the influence of the field on band frequencies are presented revealing the possibility to discriminate by IR spectroscopy between opposite dipole directions. The experimental results suggest the formation of a remanent field in the samples during poling.
Cold drawing experiments with polyethylene gel fibres
Authors: Bauer A. , Hofmann D. , Schulz E. 
Published: April 2003

AbstractHigh strength/high modulus fibres can be prepared by cold drawing of UHMW‐PE gel fibres. It is shown that the crystalline order in this fibres is not perfect. The supermolecular structure is characterized by a shish‐kebab morphology. Results of X‐ray and mechanical investigations permit to explain the drawing process by a three‐step mechanism of molecular orientation and stretching coupled with molecular and fibrillar sliding.
Synthese und charakterisierung der in anionischen systemen hergestellten polaren hybridmakromoleküle
Authors: Erussalimsky B. L. , Berger W. , Morgenstern U. 
Published: April 2003

AbstractPfropf‐ und Copolymere aus polaren Monomeren werden hinsichtlich ihrer Synthese und Charakterisierung näher beschrieben. Im Falle der Pfropfcopolymere sind aktivierte P2VP‐, P4VP, PVAC‐ und PMMA‐Ketten die Voraussetzung für die Monomeraddition. Dabei ablaufende mögliche Reaktionen werden diskutiert. Gut definierte Blockcopolymere sind zugänglich, wenn die kurze Lebensdauer der AN‐Ketten für die weitere Monomeranlagerung ausgenutzt wird. Die Untersuchung der chemischen Uneinheitlichkeit derartiger Systeme ist kompliziert.
Characterization of chloroacetylated/sulfonated cellulose membranes for hemodialysis by spectroscopical methods
Authors: Krämer S. , Dietel R. , Haupold G. , Lukas J. , Malsch G. , Paul D. 
Published: April 2003

AbstractSurface characterization techniques (ATR‐IR, ESCA and SEM‐EDX) have been used to obtain information of the surface chemical composition of modified cellulosic dialysis membranes. Chemical modification of membranes can be defined and controlled correlations between surface chemistry and hemocompatibility of membranes can be made.
Morphology of poly(2,5‐thiophenediyl) prepared by electropolymerization of 2,2′;5′,2″‐terthienyl
Authors: Koßmehl G. , Fechler D. , Plieth W. 
Published: April 2003

AbstractPoly(2,5‐thiophenediyl) (2) was prepared electrochemically from 2,2′;5′,2″‐terthienyl (1) on various metal electrodes (Pt, Au, Ni, Ni sputtered with Au) in acetonitrile, with tetrabutylammonium perchlorate as an electrolyte salt under application of varying temperatures (−5°C, room temperature) and current densities (0.05 to 1 mA/cm2). Coatings with a rough surface structure were formed by higher current densities, whereas low current densities built up a homogeneous, compact and smooth surface structure. Ni electrodes coated with Au formed such smooth surface structures even at higher current densities.
Template copolymerization of methacrylic acid and acrylic acid
Authors: Połowiński S. 
Published: April 2003

AbstractThe copolymerization of methacrylic acid and acrylic acid in toluene was investigated and the reactivity coefficients r1 and r2 have been determined. With dioxane as the solvent, deviations from the Mayo‐Lewis equation were observed. The copolymerization was further carried out in presence of poly(ethylene glycol) and the reactivity coefficients for the template copolymerization in toluene and benzene were determined. A slight increase of r1 and decrease of r2 have been established. The results are discussed.
Interpretation of the 13C‐NMR spectrum of poly(vinyl butyral) by low molecular weight model compounds
Authors: Lebek B. , Krause A. , Schlothauer K. , Marschner H. 
Published: April 2003

AbstractThe formation of Cyclic, open, and semiacetals on model substances with different numbers and arrangement of hydroxyl groups and the possibility to distinguish between them was shown by 13C‐NMR measurements. Informations on the course of acetalation were obtained from propanetriol‐1.2.3 and hexanetriol‐1.2.6 which had been converted with various quantities of butyraldehyde.
Mechanical properties of binary mixtures of high molecular poly(ethylene oxide) and alkali metal salts
Authors: Bogdanov B. , Uzov Ch. , Michailov M. 
Published: April 2003

AbstractThe mechanical properties of thin foils of binary systems of high molecular weight poly(ethylene oxide) and salts of alkali metals (NaSCN, KSCN, NaI, KI) have been investigated as a function of composition. The yield strength, tensile strength, elongation at break and Shore hardness of the foils change nonlinearly with the increase of alkali salt content. It was established that the systems PEO‐NaI, PEO‐KSCN and PEO‐KI are noncrystalline in a concentration range of alkali salts corresponding to 9 mol PEO per 1 mol alkali salt and they are in a rubbery or plastic state at room temperature.
A comparison of X‐ray methods for structure refinement of Langmuir‐Blodgett multilayers
Authors: Reiche J. , Pietsch U. , Fink H.‐P. , Lemmetyinen H. 
Published: April 2003

AbstractThe possibilities and limits of structure refinement of Langmuir‐Blodgett films by means of symmetrical reflection of X‐rays are described using the example of a stearic acid multilayer. Three different techniques for the determination of the electron density profile from reflectivity data are compared: a Fourier method, a Patterson method, and model calculations. The important role of the a priori information for finding the best structure model is outlined.
Untersuchungen zur radikalischen Copolymerisation von Dimethyl‐diallyl‐ammoniumchlorid mit Vinylacetat und Funktionalisierungsreaktionen der Copolymere
Authors: Janietz S. , Hahn M. , Jaeger W. 
Published: April 2003

AbstractDie radikalische Polymerisation von Dimethyl‐diallyl‐ammoniumchlorid mit Vinylacetat in methanolischer Lösung verläuft als nichtideale, nichtazeotrope Copolymerisation. Die nach der Kelen‐Tüdös‐Gleichung berechneten Reaktivitätsverhältnisse wurden zur r1 = 1,95 und r2 = 0,35 bestimmt. Die resultierenden Polymere sind relativ niedermolekular und im gesamten Zusammensetzungsbereich in Wasser löslich. An ausgewählten Copolymeren wurden Modifizierungsreaktionen wie Hydrolyse, Acetalisierung und Acylierung durchgeführt, die Produkte mit veränderten Eigenschaften ergaben.
Einfluß der scherbedingungen auf das koagulationsverhalten von lösungen aus polyacrylnitril unterschiedlicher molmasse
Authors: Fritzsche P. , Makschin W. , Hartig S. , Abel Ch. , Lehmann I. , Leonhardt H.‐W. 
Published: April 2003

AbstractBei der Bildung von Fäden aus Acrylnitrilpolymeren nach dem Naßspinnprinzip bewirkt eine Erhöhung der Molmasse der Polymere eine Herabsetzung des maximal erreichbaren Düsenabzuges bei gleichzeitig geringerem Düsenverzugsverhältnis. Der maximale Reckgrad der ersponnenen Fäden sinkt mit steigender Molmasse und nimmt darüber hinaus mit steigendem Düsenverzug ab. Unter vergleichbaren Bedingungen hergestellte Fäden besitzen bei höherer Molmasse trotz gleicher erzielter Festigkeiten einen geringeren Orientierungsgrad. Die Erzielung von Hochleistungseigenschaften an naßgesponnenen Fäden erfordert daher ein neues Koagulationskonzept, das sowohl polymer‐als auch prozeßimmanente Faktoren einschließt.
Principles of polymerization. 3rd edition. By Georg Odian. A Wiley‐Interscience Publication. ISBN 0‐471‐61020‐8. John Wiley & Sons, New York/Chichester/Brisbane/Toronto/Singapore 1991.768 p., cloth cover, £ 47,50
Authors: Tauer K. 
Published: April 2003

AbstractNo Abastract.