bluuebunny/crossref_metadata_2025_split huggingface dataset:
Niederdruckumkehrosmose mit modifizierten polyacrylnitril‐ultrafiltrationsmembranen
Authors: Becker Margot , Hicke Hans‐Georg , Eisold Christiane , Buschatz Heinz , Paul Dieter 
Published: April 2003

AbstractDie chemische Modifizierung von Polyacrylnitril‐Ultrafiltrations(PAN‐UF)‐Membranen mit Hydroxylamin führt zu Niederdruckumkehrosmose‐Membranen, die neben verbleibenden Nitrilguppen sowohl Amidoxim‐ als auch Hydroxamsäuregruppen enthalten und bei einem pH von 4,0 bis 6,5 positiv geladen sind.Die Wasserdurchlässigkeit der Membranen sinkt durch diese Modifizierung von 400 L h−1 m−2 auf 15 L h−1 m−2 (p = 0,3 MPa). Eine umfassende Charakterisierung erfolgte anhand von Trennkurven, IR‐ und NMR‐Spektren, der Hg‐Porosimetrie, der Membranpotentialmessung und der Trennleistung für verschiedene Metallsalze. Infolge des Donnan‐Ausschlusses haben diese Membranen für zweiwertige Metallionen, wie die Härtebildner des Wassers Ca2+ und Mg2+, eine Rückhaltung von 88% bei einem Filtratfluß von 8 L h−1 m−2 (p = 0.3 MPa). Für Schwermetallionen wie Cu2+ und In3+ sind bei annähernd gleicher Rükhaltung wesentlich höhere Durchflußraten von 90 bis 100 L h−1 m−2 (p = 0,3 MPa) möglich.Im wäßrigen, schwermetallionenfreien Medium unterliegen die Amidoxim‐ und Hydroxamsäuregruppen der Hydrolyse, und es entstehen an der Membranoberfläche Carboxylgruppen, durch die mehrwertige Anionen zurückgehalten werden. Ihr Vermögen zur Wasserenthärtung bleibt erhalten.
Zum thermodynamischen verhalten von polystyrol (PS)/poly(vinylmethylether) (PVME)‐blends
Authors: Radusch Hans‐Joachim , Tung Ngo Trinh , Wohlfarth Christian 
Published: April 2003

AbstractDas Blendsystem PS/PVME weist ein Phasenverhalten mit einer unteren kritischen Entmischungstemperatur (LCST‐Verhalten) auf, das mit dem Modell von Dee und Walsh sowie mit der kontinuierlichen Thermodynamik modelliert und diskutiert wurde. Die Berechnungsergebnisse zeigen, daß die Prigogine‐Zustandsgleichung in der Lage ist, das reale PVT‐Verhalten der Polymerschmelze recht gut anzupassen. Die mit dem Modell von Dee und Walsh erhaltene Spinodalkurve liefert eine sehr gute Übereinstimmung mit den Ergebnissen der Trübungsmessungen. Die Modellrechnungen zeigen eine Verbesserung der Verträglichkeit dieses Polymersystems bei hohem Druck. Mit der kontinuierlichen Thermodynamik konnte der Einfluß der Polydispersität auf das Phasenverhalten des Blendsystems deutlich gemacht werden. Eine merkliche Verschiebung des kritischen Punktes aus dem Minimum infolge der breiten Molmassenverteilung von PVME wird deutlich.
Synthesis of ketonic resins from self‐polymerization of acetone, 2. Action of bases on acetone and the synthesis of halogenated and diels‐alder adducts
Authors: Cataldo Franco 
Published: April 2003

AbstractAcetone was polymerized under the action of NaOH, NaOEt or KOH in ethanolic or methanolic solutions at a molar ratio acetone/base ranging from 1.5 : 1 to 12:1 to give a liquid resin. The liquid resin was obtained with a maximum yield of 60% over initial acetone and was always accompanied by variable quantities of isophorone. The polyenic nature of the ketonic resin obtained was shown by infrared and electronic spectroscopy, as well as by using an isophorone resin as model compound. It is proposed that the structure of the acetone resin should be a condensation product of acetone/ isophorone and isophorone/isophorone. Acetone resins (PCA) obtained both with Brönsted acids (PCA‐B), Lewis acids (PCA‐L) and alkaline catalysts (PCA‐A) can be easily halogenated up to certain degrees of saturation. All PCA resins form Diels‐Alder adducts with maleic anhydride, p‐benzoquinone and fumaric acid. The adducts can contain from 1 to 2 dienophile molecules per molecule of resin.
Polymerization of butyl acrylate in microemulsion. Locus of initiation
Authors: Potisk P. , Vašková V. , Capek I. , Klimová M. 
Published: April 2003

AbstractThe locus of initiation in the microemulsion polymerization of butyl acrylate initiated by water‐soluble ammonium peroxodisulfate, partially water‐soluble azoisobutyronitrile and oil‐soluble dibenzoyl peroxide is determined almost exclusively by the initiator solubility in respective phases of the reaction system, regardless of the overall character of the system. This conclusion was drawn taking into account the results of the microemulsion study in comparison with those from inverse microemulsion polymerizations. The polymerization experiments were carried out in the presence of stable nitroxyl radicals acting as polymerization inhibitors of different solubility in water. The consumption of the inhibitor radicals by the combination with radicals from initiator decomposition was followed by electron spin resonance spectrometer.
Effect of structure on the thermal behaviour of ethynyl‐terminated imide resins
Authors: Alam Sarfaraz , Varma Indra K. 
Published: April 2003

AbstractA series of ethynyl‐terminated aromatic imide monomers containing phosphine oxide in the backbone were synthesized by the reaction of tris(3‐aminophenyl) phosphine oxide (TAP) or bis(3‐aminophenyl)methyl phosphine oxide (BAP) with pyromellitic dianhydride (PMDA) or 3, 3′,4, 4′‐benzophenone tetracarboxylic acid dianhydride (BTDA) or 4, 4′‐perfluoroisopropylidenebis(phthalic anhydride), and 3‐ethynyl aniline. Structural characterization was done by infrared, nuclear magnetic resonance spectroscopy and elemental analysis. Thermal characterization was done by differential scanning calorimetry and thermogravimetric analysis. The decomposition temperatures of cured resins were above 500°C in nitrogen atmosphere. Char yield at 800°C ranged from 52–63.5%.
Modification of transport properties of ion exchange membranes, XIII. Surface‐modified cation exchange membranes prepared from polyamines and a copolymer membrane containing p‐stryenesulfonyl chloride
Authors: Takata Kuniaki , Ihara Hirofumi , Sata Tosikatu 
Published: April 2003

AbstractA membrane precursor was prepared by the copolymerization of p‐styrenesulfonyl chloride and divinylbenzene in the presence of a poly(vinyl chloride) supported cloth. The surface of the membrane was treated with various amines, and then the sulfonyl chloride groups in the internal part of the membrane were hydrolyzed with an aqueous sodium hydroxide solution in organic methanol or acetone solvent. Hydrolysis conditions were examined for the introduction of the sulfonic acid groups. The membrane modified by ethylenediamine exhibited slightly bipolar properties during the electrodialysis of seawater. Surface‐modified membranes using tetraethylenepentamine exhibited excellent monovalent cation permselectivity, low membrane electric resistance, and long performance durability during the electrodialysis of seawater.
Water‐soluble polymers by interaction of sulfonic polyelectrolytes with dipolar aprotic solvents
Authors: Drǎgan Demetra 
Published: April 2003

AbstractThe solution of the strongly acidic polyelectrolyte poly(2‐acrylamido‐2‐methylpropanesulfonic acid) in N,N‐dimethylformamide or N,N‐dimethylacetamide is accompanied by a simultaneous reaction of amidation of the sulfonic acid to the corresponding sulfonamide groups. Various compositions of binary copolymers poly[(2‐acrylamido‐2‐methylpropanesulfonic acid)‐co‐(2‐acrylamido‐2‐methylpropane‐N,N‐dimethylsulfonamide)] up to high amidation conversions of 98–99% were synthesized and characterized. The amidation of the sulfonic acid groups appears to be a common reaction for different copolymers having 2‐acrylamido‐2‐methylpropanesulfonic acid moieties but fails with the free monomer.
Conductive composites prepared via a propagating polymerization front
Authors: Szalay Judit , Nagy István P. , Barkai István , Zsuga Miklós 
Published: April 2003

AbstractA novel material, a conducting composite with variable temperature coefficient of electrical conductivity, was prepared in a propagating front of an addition polymerization. Graphite and zinc particles were incorporated into an acrylamide‐triethylene glycol dimethacrylate copolymer. Specific electric resistance values of the materials yielded were measured at room temperature and also conductivity measurements were performed in the range of 20–220°C. The basic recipe was modified by doping the conductive composite materials with microscopic‐scale‐size particles of several inorganic and organic compounds, resulting in significantly different conductivity features of the composite. Scanning electron microscopy was performed to study the morphology of materials yielded. No percolative patterns containing zinc particles were found to support the conductive behavior of the composite. In accordance with to the modifying effect of doping materials we suspect that the acrylamide‐triethylene glycol dimethacrylate copolymer plays a specific role in the electric conductivity behavior of the composite material.
Fundamental properties of fluoropolyether‐based resins and related coatings
Authors: Simeone Giovanni , Turri Stefano , Scicchitano Massimo , Tonelli Claudio 
Published: April 2003

AbstractNew fluoropolyether polyolic resins are presented suitable to be cured with conventional hardeners as polyisocyanates or melamines. These resins are prepared by addition of fluoropolyether macrodiols (Fomblin® ZDOLTX) of various molecular weights to isophorone diisocyanate (IPDI) to give oligomeric NCO‐terminated prepolymers. The final hydroxy functionality is obtained by the reaction of those prepolymers with trimethylolpropane (TMP). The viscosity of the resins is measured at various concentrations (weight fraction 0.8 – 0.4) and temperatures (T = 25–65°C). The results are discussed in terms of the Erickson equation (η vs. concentration) and using the WLF and Arrhenius models (η vs. T). The thermal behavior is studied by DSC for both the resins and cured films indicating the presence of two Tgs, corresponding to the segregated fluorinated and hydrogenated phases, the former particularly evident with the highest molecular weights of the fluorinated macromer. Tensile curves of selfsupported films are then analyzed showing an evident tough‐plastic behavior especially for the isocyanate‐cured films. The application of such materials as high‐durability clear coats is finally proposed.
Modification of melamine‐formaldehyde moulding compounds with epoxy resins
Authors: Braun Dietrich , Unvericht Reinhard 
Published: April 2003

AbstractIn order to improve dimension stability and toughness of melamine formaldehyde moulding materials (MF), compatible bisphenol A epoxy resins (EP) with additional methylol groups were synthesized and characterized. Crosslinking of those epoxyresol resins with 2‐ethyl‐4‐methylimidazole in the presence of MF resin was investigated. Transfer‐moulded specimens revealed a two‐phase morphology in which the EP phase is used as a host for modification with carboxylic functionalized oligomeric NBR rubber (CTBNX), which is not effective in MF moulding materials alone. The addition of 0.5 – 4 wt.‐% CTBNX to the MF moulding materials at an epoxy content of maximum 20 wt.‐% results in 50–100 % increase of elasticity and toughness without serious decrease in stiffness and heat deflection temperature, provided that covalent interfacial bonds exist. In addition, the post‐shrinkage of MF parts decreases if a moderate EP/CTBNX content is introduced.
New polymer multilayer pervaporation membrane
Authors: Kononova Svetlana V. , Kuznetsov Yuri P. , Apostel Regine , Paul Dieter , Schwarz Hans‐Hartmut 
Published: April 2003

AbstractThe formation, morphology and transport properties of a new multilayer pervaporation membrane have been studied.This membrane consists of a microporous support based on a poly(amideimide), an intermediate poly[2‐(N,N‐dimethylamino)ethyl methacrylate] layer, and a top diffusion layer of ladder polysiloxane. The membrane has low permeability for weakly polar liquids (e.g. cyclohexane); it exhibits dehydrating properties for waterisopropanol mixtures and has high productivity (up to 14.5 kg h‐1 m‐2) and high separation factor (up to 27430) when methanol is isolated from mixtures with cyclohexane. The transport properties of the membrane are discussed with respect to the Henis‐Tripodi resistance model, taking into account the hydrophobic‐hydrophilic nature of the polymers used.
Stat‐poly(Ethylene oxide‐co‐propylene oxide). Synthesis, NMR characterization and crystallinity studies. Correlation with monte carlo simulation
Authors: Hamaide Thierry , Goux Alain , Llauro Marie‐France , Spitz Roger , Guyot Alain 
Published: April 2003

AbstractLow‐molecular‐weight stat‐poly(ethylene oxide‐co‐propylene oxide) polymers have been prepared anionically using a new heterogeneous catalytic process previously reported. They were fully characterized by 1H and 13C NMR spectroscopy in order to determine the distribution of the ethylene oxide (EO)‐centered triads, as well as the average lengths of poly(ethylene oxide) (PEO) sequences. Low degrees of crystallization were determined by DSC. These copolymers have been successfully used for applications in the solid polymer electrolytes field and high levels of conductivity at room temperature have been measured. The results are in good agreement with those obtained from a Monte Carlo simulation method using the copolymerization terminal model developed for radical polymerization.
Aging of elastomers in nuclear power plants. Effect of temperature and irradiation
Authors: Dole P. , Chauchard J. 
Published: April 2003

AbstractThe thermo and radiooxidation of a poly(ethylene‐co‐methyl acrylate)‐based industrial elastomer has been studied by various techniques. As already shown in the case of thermooxidation, these elastomers lead to crosslinking reactions when submitted to γ irradiation in air. Considering that the thermooxidation rate follows an Arrhenius law, and that the radiooxidation rate is directly proportional to the dose rate, the predominant mechanism (thermooxidation or radiooxidation) can be defined, as a function of aging conditions. This method was successful for two different aging conditions.
Selective adsorption of bilirubin by macroporous poly(glycidyl methacrylate‐co‐divinylbenzene) beads
Authors: Kuroda H. , Tanaka T. , Osawa Z. 
Published: April 2003

AbstractMacroporous glycidyl methacrylate (GMA)‐divinylbenzene (DVB) copolymer beads have been synthesized and the adsorption of bilirubin, albumin and other serum components were studied. The beads composed of DVB/GMA in the weight ratio of 75/25 provide an excellent bilirubin adsorption ability. When the surface of the beads was previously coated with albumin, discriminating adsorption of the bilirubin in the serum was attained and the adsorption of albumin was depressed. In addition, when the coated albumin was crosslinked with glutaraldehyde, the excellent bilirubin adsorption ability was maintained, however, an adsorption of albumin from the serum occurred.
Synthesis and properties of transition metal complexes with branched poly(ethyleneimine)
Authors: Rivas B. L. , Seguel G. V. , Geckeler Kurt E. 
Published: April 2003

AbstractPolychelates were obtained by addition of an aqueous solution of the branched poly(ethyleneimine) (BPEI) to the aqueous solutions of Cu(II), Co(II), and Ni(II). All the polychelates were characterized by elemental analysis, FT‐IR, 1H NMR spectroscopy, thermogravimetry, and scanning electron microscopy. Conductivity and magnetic moment measurements were also carried out. The three polychelates showed a change of the chemical shift in 1H NMR spectra due to the metal ion complexing with the polyligand. Accordingly to the spectral study, the polychelates showed different geometric arrangements: Cu‐BPEI square planar, Ni‐BPEI tetrahedral, and Co‐BPEI octahedral.
New poly(vinyl chloride) blends, III. Physico‐mechanical properties
Authors: Rusu Mihai , Bucevschi Mircea‐Dan , Rusu Daniela‐Lorena 
Published: April 2003

AbstractThe concurrent influence of the processing aid (Paraloid K 120N) and the carbon black ratio, as well as the nature and the ratio of the impact modifier (CPE 3615 and Kane Ace B56 A) on the main physico‐mechanical characteristics of the poly(vinyl chloride)‐based unplasticized mixtures have been studied. The results obtained, processed mathematically and plotted graphically in the form of response surfaces, evidenced that the improvement of certain physico‐mechanical properties becomes possible by the introduction of 2.5 parts and 5.0 parts carbon black into these compounds. This is due to the introduction of impact modifiers and processing aids into the mixtures.
Microstructure and electrical conductivity of complex cathodes based on new vanadium oxides and polyether blends
Authors: Morales Enrique , Acosta Jose Luis 
Published: April 2003

AbstractThis paper studies the effect produced by different vanadium oxides on the microstructure of PEO and PEO/PPO blends by means of the analysis of the crystallization kinetics under isothermal and nonisothermal conditions. The electrical properties of the samples were characterized by complex impedance analysis. Results suggest that the additives employed (considering both carbon black and vanadium oxides) promote changes in the microstructure of PEO/PPO polymer blends because of polymer‐additive interactions. All samples tested show good conductivity properties.
Conductivities and some other properties of oxymethylene‐linked 2‐vinylpyridine‐oxyethylene multiblock copolymers
Authors: Xie Hong‐Quan , Cui Min‐Hui , Guo Jun‐Shi 
Published: April 2003

AbstractOxymethylene‐linked 2‐vinylpyridine‐oxyethylene (2VP‐EO) mulitblock copolymers doped with LiClO4 or/and tetracyanoquinodimethane (TCNQ) showed ionic electronic and mixed (ionic‐electronic) conductivity. Effects of the poly(oxyethylene) content and of the molar ratios of EO/Li and TCNQ/2VP on the conductivities of the complexes were studied. The optimum molar ratios of EO/Li and TCNQ/2VP were 10 and 1.0, respectively. The copolymers emulsified benzene/water systems and exhibited good phase‐transfer catalysis properties in the Williamson reaction of solid potassium phenolate with n‐butyl bromide. After neutralization with HCI solution, the copolymers showed polyelectrolyte solution properties.
New polyhydrazides and poly(1,3,4‐oxadiazole)s containing pendent phenoxy groups
Authors: Hamciuc Corneliu , Schulz Burkhard , Bruma Maria 
Published: April 2003

AbstractA series of new polyhydrazides containing pendent phenoxy groups has been synthesized by low‐temperature solution polycondensation of equimolar amounts of diacid dichlorides and 2‐phenoxyterephthalic dihydrazide in N‐methyl‐2‐pyrrolidi‐none (NMP). The thermal cyclization of the polyhydrazides gave the corresponding poly(1,3,4‐oxadiazole)s containing pendent phenoxy groups. The polymers were characterized by viscometry, solubility measurements, IR spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis.
In‐line‐rheometrie durch direkte wandschubspannungsermittlung
Authors: Braun Peter , Mennig Günter 
Published: April 2003

AbstractAusgehend von den Grundlagen zur Kapillarrheometrie mit den bekannten Korrekturverfahren nach Rabinowitsch und Bagley wird das traditionelle Verfahren zur Ermittlung des Düseneinlaufdrucks sowie des Wandschubspannungswerts dargestellt. Dieses Verfahren kann bei manchen Materialien zur fehlerhaften Bewertung des Fließverhaltens führen, da ein linearer Druckabfall in den Meßdüsen unterstellt wird. Daher wird eine neue Methode zur direkten Schubspannungsermittlung vorgestellt sowie die dazu notwendige Meßeinrichtung beschrieben. Es handelt sich dabei um eine in‐line integrierbare Düse, die auf der Basis eines auf Piezokraftaufnehmern gelagerten Düsenabschnitts die Reaktionskraft der strömenden Schmelze auf die Düsenwandung ermittelt.Die Meßergebnisse zeigen, daß bei der Ermittlung der Fließeigenschaften von Materialien, die ein Potential zur Strukturbildung während des Fließvorganges aufweisen, wie z. B. flüssigkristalline Polyester (LCP), mit der In‐line‐Düse korrekte Wandschubspannungen erhalten werden. Mit der klassischen Methode der Kapillarrheometrie hingegen können bei solchen Materialien nur dann vergleichbare Ergebnisse gewonnen werden, wenn zusätzliche Annahmen über den Druckverlauf in der Meßdüse gemacht werden.
Effect of electron beam radiation on mechanical and electrical properties of poly(ethylene‐co‐vinyl acetate)
Authors: Datta Sujit K. , Chaki T. K. , Khastgir D. 
Published: April 2003

AbstractEthylene‐vinyl acetate (EVA) copolymer (12% vinyl acetate content) is subjected to electron beam irradiation using trimethylolpropane trimethacrylate (TMPTMA) as a radiation sensitizer. Mechanical and electrical studies of these irradiated samples show that the strength properties (tensile strength, elongation at break) are increased with radiation dosage up to an optimum radiation dose and sensitizer level above which the properties begin to deteriorate. Crosslinking of the polymer takes place on irradiation which is attributed to an increased gel content with increasing radiation dose. Compared to the original samples both dielectric constant and dielectric loss factor decrease for samples subjected to irradiation.
The effects of a slushing oil on the curing and degradation behavior of an oil‐accommodating epoxy adhesive
Authors: Hong S. G. , Shu H. X. , Lin J. J. , Young J. D. 
Published: April 2003

AbstractThe effect of aliphatic slushing oil on the curing and degradation behavior of an oil‐accommodating epoxy adhesive is studied by using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The results of FTIR and DSC indicate that the curing rate of the tested epoxy system is little affected in the presence of the oil. However, the decrease of the curing exotherm accompanied with a broadening of the glass transition confirms that the oil can affect the curing mechanisms and may change the structure of the cured resin. Additionally, it is evident from the TGA results that the thermal resistance of the resin deteriorates in the presence of the oil, which is attributed to the changes in the structure and the degradation mechanism of the epoxy system.
Homogeneous synthesis of cellulose p‐toluenesulfonates in N,N‐dimethylacetamide/LiCl solvent system
Authors: Rahn Kerstin , Diamantoglou Michael , Klemm Dieter , Berghmans Hugo , Heinze Thomas 
Published: April 2003

AbstractPure cellulose p‐toluenesulfonates (tosylates) with an insignificant formation of chlorodeoxy groups were prepared by reacting cellulose dissolved in a solution of N,N‐dimethylacetamide and LiCI with tosylchloride (Tos‐CI) in the presence of triethylamine within 24 h at 8°C. Various cellulosic starting materials with a degree of polymerization from 280 to 5 100 were used. The samples obtained were characterized by means of elemental analysis, FTIR and 13C NMR spectroscopy, and their intrinsic viscosities. The rise of the molar ratio of Tos‐CI/anhydroglucose unit (AGU) from 0.6 to 9.0 leads to an increase in the degree of substitution (DS) from 0.4 up to a maximum value of 2.3. The cellulose tosylates are readily soluble in common organic solvents like dimethyl sulfoxide (within the whole DS range) and in N,N‐dimethylacetamide, N,N‐dimethylformamide, acetone, tetrahydrofuran and trichloromethane depending on DS. As revealed by 13C NMR spectroscopy a faster tosylation takes place at the O‐6 atom of AGU compared with the O‐2/3 atoms. This was additionally confirmed by analysis of the corresponding iododeoxy celluloses synthesized with NaI in acetylacetone. Furthermore, some important properties as stability against alkaline and heat were studied as well.