bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sorption von Silber an chlormethyliertem Polystyrol
Authors: Lieser K. H. , Hofmann B. , Stingl U. 
Published: April 2003

AbstractSilberionen werden aus wäßrigen Lösungen an chlormethyliertem Polystyrol mit einem Verteilungskoeffizienten von etwa 100 ml/g gebunden, dagegen nicht an Polystyrol selbst. Dies spricht für eine direkte Wechselwirkung zwischen Ag+‐Ionen und den Chloratomen des chlormethylierten Polystyrols im Sinne der Bildung eines 1 : 1‐Komplexes. In Anwesenheit von 0,1 mol/1 Ammoniumionen werden im Bereich von pH 4 bis pH 6 etwas niedrigere Verteilungskoeffizienten gefunden, in Anwesenheit von 10−3 mol/l Na2S2O3 betragen sie nur etwa 6 ml/g. Aus Lösungen, die 1 mol/l NaCl oder 0,1 mol/l Na2S2O3 oder 10−3 mol/l NaCN enthalten, wird Silber nicht in meßbaren Mengen sorbiert, weil die Komplexbildung in Lösung überwiegt. Die experimentellen Ergebnisse und ihre Bedeutung für die Praxis werden diskutiert. In Trennsáulenversuchen wird die Abtrennung von Silberionen aus verdünnten Lösungen demonstriert.
Gemeinsame kondensation von bisphenol A, melamin und formaldehyd
Authors: Braun Dietrich , Vargha Viktoria 
Published: April 2003

AbstractDie gemeinsame Kondensation von Bisphenol A, Melamin und Formaldehyd wurde mit Hilfe der Gelpermeationschromatographie, der 13C‐NMR‐Spektroskopie, IR‐Spektroskopie und Elementaranalyse untersucht. Wegen der hohen Kondensationsgeschwindigkeit verläuft die Reaktion in Gegenwart der drei Komponenten nur im Bereich von pH 6−10 kontrollierbar. Bei pH 6 und 7 überwigt die Kondensation zwischen Melamin und Formaldehyd. Mit steigendem pH‐Wert tritt die Reaktion von Bisphenol A mit Formaldehyd in den Vordergrund und führt bei pH 10 zu hochmolekularen Kondensationsprodukten.Auf direkte Cokondensation hinweisende Methylenverknüpfungen zwischen der phenolischen Komponente und Melamin konnten nicht nachgewiesen werden. Die Kondensationsprodukte des Melamins bzw. des Bisphenol A mit Formaldehyd lassen sich aber nicht mehr vollständig aus den Reaktionsgemischen der Vorkondensation abtrennen, was dafür spricht, daß die Komponenten über Methylenetherbrücken und/oder intermolekularen Wasserstoffbrücken miteinander verknüpft sind.
Improved method for the preparation of ethylene adsorbent from copper(I) chloride and polystyrene resin having amino groups
Authors: Komiyama Makoto 
Published: April 2003

AbstractSelective adsorbent for ethylene was prepared by stirring 101 mmol of copper(I) chloride and 10 g of a macroreticular type polystyrene resin having amino groups in 1:1 acetonitrile‐water mixture (80 cm3) for 2 h at 20°C, followed by the evaporation of the liquid at 20°C under 3 mmHg. The adsorbent exhibits much larger adsorption rate than the one prepared by the evaporation of the liquid at 80°C. In addition, desorption of the adsorbed ethylene for the present adsorbent is more efficient than the one obtained at 80°C. The adsorbing capacity for ethylene of the present adsorbent is 7.6 times as large as that for ethane, and the adsorbing capacity for nitrogen and hydrogen is none at 20°C under 1 atm. The significant effect of the preparation temperature on the adsorbing and desorbing abilities of the adsorbents is ascribed to difference in the porosities of the resins in the adsorbents. The present adsorbent has a large potential for the application to separation of ethylene from gas mixtures in industry.
Preparation of cyclodextrin membrane‐modified electrodes as sensor materials
Authors: Komiyama Makoto 
Published: April 2003

AbstractCyclodextrin membrane‐modified electrodes as sensor materials have been prepared by dipping platinum electrodes in the water suspensions of an oriented cyclodextrin polymer, followed by drying the polymer layers on the electrodes. The polymer is obtained by the solid‐liquid reaction between the crystal of cyclodextrin inclusion complex and hexamethylene diisocyanate in anisole. The thickness (2 − 80 μm) of the cyclodextrin membrane is satisfactorily controlled by changing the concentration of the water suspension of the polymer. The cyclodextrin membranemodified electrodes show a significant response to p‐nitrophenolate in water which is highly in contrast with no measurable response to o‐ and m‐nitrophenolates.
Kinetics of polyesterification and models, 2. Kinetics and mechanism of 1,1,1‐trimethylolpropane esterification by long‐chain carboxylic acids at technological conditions
Authors: Bacaloglu Radu , Mǎtieş Marius , Csunderlik Carol , Cotarcǎ Livius , Moraru Ariana , Gros Josif , Marcu Nicolae 
Published: April 2003

AbstractKinetics of 1,1,1‐trimethylolpropane esterification by long‐chain (C4 —C18) carboxylic acids has been followed by GLC, HPLC, 1H‐NMR, and potentiometric titrimetry. The system composition evolution was established at technological conditions, i.e. molar ratio between 1/1 and 1/3 and temperatures between 160 and 205°C. The rate constants of the three involved consecutive reactions were determined according to the kinetic law which assumes a partial order of 1.5 with respect to the acid and 1.5 with respect to the alcohol.Once the three rate constants k1, k2, and k3 are known by direct determination, a computer simulation for the esterification process has been carried out. The experimental variation of the component concentrations and the calculated values show a proper agreement, thus proving the selected kinetic model.
Synthesis of chiral polymers containing dimethylaminobornanol moieties
Authors: Liu Jui‐Hsiang 
Published: April 2003

AbstractIn order to investigate the influence of spacer on the stereoselectivity of the addition of n‐butyllithium to aldehydes, three kinds of chiral polymers containing dimethylaminobornanol moieties were synthesized. The polymerization of the chiral monomers was carried out under various conditions. Cross‐linked chiral polymers were prepared by copolymerization of the chiral monomers with commercial p‐divinyl benzene. The conversion was found to be affected by the kind of solvents. Asymmetric addition of n‐butyllithium to benzaldehyde was carried out in the presence of the chiral polymers having dimethylaminobornanol moieties, and it was found that all three kinds of chiral polymers are effective for the asymmetric addition. Advantages of insoluble chiral polymers such as the ease of separation from products and the ability to be recycled, are discussed.
Ein modell zur quantitativen beschreibung der morphogenesis von PVC‐S, II Modellierung der inneren morphologie — modellvorschlag
Authors: Weickert Günter , Platzer Bernd , Weißenborn Klaus‐Dieter , Klodt Rolf‐Dieter , Henschel Ines 
Published: April 2003

AbstractIn der vorliegenden Arbeit wird ein mathematisches Modell für die Berechnung der Morphogenesis von PVC‐S entwickelt, das die hierarchische Struktur von PVC‐S‐Körnern widerspiegelt. Die Bildung der Polymerketten wird auf der Basis eines selektierten kinetischen Modells beschrieben. Für den Prozeß der Aggregation der Teilchen innerhalb eines Subkornes wird ein Modellansatz aus dem Einstein‐Smoluchowski‐Gesetz abgeleitet. Die Modellparameter des Gesamtmodells sind physikalisch‐chemisch begründbar — lediglich ein Parameter dient als effektive Konstante zur integralen Erfassung von Prozessen, die einer genügend genauen und hinreichend einfachen Modellierung zur Zeit noch wenig zugänglich sind. Das aggregative Wachstum der Teilchen in den verschiedenen hierarchischen Ebenen wird mit Hilfe vereinfachter geometrischer Annahmen beschrieben. Auf diese Weise sind die Zahl und die Größe der Teilchen innerhalb der PVC‐Subkörner als Funktion der Reaktionszeit berechenbar.
In vitro blood compatibility of glow discharge‐grafted silicone rubber tubings
Authors: Jansen Bernd , Steinhauser Hermann , Prohaska Wolfgang 
Published: April 2003

AbstractSmall diameter silicone rubber tubings were grafted with vinyl methyl acetamide using a glow discharge treatment. Discharge conditions were chosen which allowed grafting exclusively on the inner surface of the tubings. Increasing the voltage as well as a posttreatment at increased monomer vapor pressures leads to higher conversions as a posttreatment at increased monomer vapor pressures leads to higher conversions as determined by contact angle measurement and gravimetry; no influence of the discharge pressure could be observed. Human blood plasma exposed to the grafted tubings showed some alterations in comparison to blood plasma exposed to ungrafted tubings. A prolongation of the activated partial thromboplastin time and lower levels of factor V and platelet factor 4 were measured, while almost no differences in the generation of fibrinopeptide A could be noticed. Platelet adhesion on grafted tubings was less than on unmodified tubings.
Natural graphite filled polyolefins — electrical and electrochemical behavior
Authors: Krohn Holger , Beck Fritz , Zahn Axel 
Published: April 2003

AbstractComposite materials with 80 wt.‐% natural graphite and 20 wt.‐% polyolefins have been characterized for their application as positive electrodes in batteries. With respect to graphite, resistivity is enhanced by a factor of 104 (ρ = 1–10 Ωcm), and the anisotropy factor is lowered to 10. A thin polymer film barrier and/or a thin bilayer of graphite surface groups between the graphite flakes, crossed by electron tunneling, is responsible for this and for a pronounced field effect of resistivity.The presence of a polymer binder is also indicated by a formation effect in the course of the first anion intercalation cycles performed by electrochemical experiments. Long term cycling of a model cell reveals a strong influence of the mechanical properties of the polyolefin binders. Those with high tensile strength lead to a much poorer cycle life than those with low tensile strength, where cycle numbers up to 5000 (one hour charge) have been obtained. The latter material has an improved compatibility to the periodical volume alterations in the course of electrochemical cycling.
Elektrische leitfähigkeit von rußgefüllten polyethylenen und polyethylenmischungen
Authors: Grigorova Marietta , Mladenov Ivan , Zlatkov Todor , Michailov Marin 
Published: April 2003

AbstractUntersucht wurde die elektrische Leitfähigkeit von mit Acetylenruß gefüllten Systemen mit Ein‐ bzw. Zweikomponentenmatrix aus Polyethylenen verschiedener Dichte und unterschiedlicher Viskosität im Schmelzzustand.Es wurde festgestellt, daß unter isothermen Bedingungen die elektrische Leitfähigkeit mit steigendem Kristallinitätsgrad und Schmelzindex der Polyethylenkomponenten steigt. Dabei übt das Fließverhalten der Polyethylenmatrix einen sehr wesentlichen Einfluß aus.An ausgewählten Objekten wurde die Temperaturabhängigkeit der elektrischen Leitfähigkeit untersucht. Die wesentlichste Abnahme der Leitfähigkeit mit der Temperaturehöhung wurde bei den rußgefüllten Polyethylenen hoher Dichte festgestellt.Die erhaltenen Resultate eröffnen die Möglichkeit einer geregelten Herabsetzung des elektrischen Volumenwiderstandes von rußgefüllten Polyethylensystemen durch die gezielte Änderung ihrer Matrix‐Komponenten‐Zusammensetzung.
Blends of chlorinated isotactic polypropylene with poly(ethylene‐co‐vinyl acetate) I. Effect of component polymers composition on the blend miscibility
Authors: Lee Seung Soo , Chung Ki‐Hyun , Kim Kwang Soo , Jung Jin Chul 
Published: April 2003

AbstractChlorinated isotactic polypropylenes (CPP) having various chlorine contents were blended with poly(ethylene‐co‐vinyl acetate)s (EVA) having various vinyl acetate (VA) contents. The blends were made by casting films from dilute THF solutions and miscibility of the blends was identified by single glass transition temperature, which was confirmed by DSC and dynamic mechanical measurements. Based on the miscibility data from a large number of CPP/EVA combinations, a miscibility map was depicted where CO equivalent weight (CO‐EQW) of EVA was plotted against chlorine equivalent weight (Cl‐EQW) of CPP.Though an attractive interaction between CPP and EVA could be detected in all the miscible and immiscible blend pairs, miscibility of the CPP/EVA blends could solely be observed in a relatively narrow range of Cl‐EQW ca. 65–100 and CO‐EQW ca. 170–230.
Polymerization of diallyldimethylammonium chloride in inverse emulsion, II. Molecular weight and electrical conductivity of the polymer
Authors: Huang P. C. , Reichert K.‐H. 
Published: April 2003

AbstractThe dependence of molecular weight of poly(diallyldimethylammonium chloride) on conversion was studied and a model is proposed for the calculation of the conversion dependence of molecular weight under consideration of gel effect and chain transfer reactions to monomer and polymer. The influence of tetramethylammonium chloride concentration on the ionic conductivity of the solid polymer was studied. A maximum specific ionic conductivity of 2.2 · 10−4 S cm−1 was measured.
Kinetics of polyesterification and models, 3. Kinetics and mechanism of pentaerythritol esterification by long‐chain carboxylic acids at technological conditions
Authors: Bacaloglu Radu , Mǎtieş Marius , Cotarcǎ Livius , Gros Iosif , Moraru Ariana , Tǎrnǎveanu Alexandru 
Published: April 2003

AbstractKinetics of the esterification of pentaerythritol by long‐chain carboxylic acids (C7 – C18) has been followed by potentiometric titrimetry. A simplified approach for the estimation of the rate constant values and the rate constants of the consecutive processes was developed according to the previous established kinetic law for similar systems.A computer simulation of the component concentrations variation has been carried out in order to prove the selected kinetic model.
Correlation between the production parameters and the mechanical properties of novolac resins reinforced with carbon fibers
Authors: Simitzis Johannis 
Published: April 2003

AbstractUnidirectional composite materials of novolac resin with carbon fibers were fabricated according to the prepreg method. Novolac resin was prepared by polymerization of phenol with formaldehyde (mole ratio 1 : 0.82) in the presence of oxalic acid as catalyst (1.5 wt.‐% to phenol). The curing of novolac resin was performed with hexamethylenetetramine (hexa), while the appropriate proportion was determined by using the IR‐spectroscopy.Specimens of novolac/hexa (weight ratio 14:1) reinforced with carbon fibers commercially available were fabricated under different conditions (e.g. different thermal programs and different proportions of novolac/carbon fibers). The mechanical properties of the fabricated specimens (like flexural strength, tensile strength, etc.) were determined and their structure was examined by scanning electron microscopy.By increasing the volume proportion of carbon fibers, not only all mechanical properties of the composite material were increased, but also their degree of utilization was increased and also the production conditions had greater influence. Concerning the specimens produced by the same proportion of carbon fibers (e.g. 15 vol.‐%) their mechanical properties were improved by increasing the curing of novolac. The degree of curing of novolac during the initial phase (gel time) and during the ultimate phase (post‐curing) can be followed with the aid of IR‐spectra of the cured resin, while the degree of curing for the intermediate phase can be obtained only indirectly from the values of the mechanical properties of the corresponding specimens.From the correlation between the production parameters and the mechanical properties of the samples the optimal conditions for processing of the thermopress for the manufacture of carbon fiber reinforced novolac were concluded (1. phase: T1 = 125–145°C, t1 = 20 min – 1 h, without pressure; 2. phase: T2 = 180–195°C, t2 = 40 min, P2 ≃ 1,5 kN/cm2).
Ein modell zur quantitativen beschreibung der morphogenesis von PVC‐S, III. Modellierung der inneren morphologie — parameterstudien
Authors: Weickert Günter , Henschel Ines , Platzer Bernd , Klodt Rolf‐Dieter , Weißenborn Klaus‐Dieter 
Published: April 2003

AbstractIn der vorliegenden Arbeit werden die Eigenschaften des früher1,2 entwickelten Modells untersucht und diskutiert. Die Variation der Modellparameter zeigt einen großen Einfluß der Aggregationsprozesse auf die Subkornmorphologie. Bei niedrigen Monomerumsätzen ist das Zeitintervall zwischen zwei aufeinanderfolgenden Aggregationsschritten sehr klein, so daß für das Teilchenwachstum die Geschwindigkeit der Aggregation der Unterstrukturen entscheidend ist. Im Bereich zwischen 5% und 20% Monomerumsatz sinkt die Aggregationsgeschwindigkeit sehr stark, so daß für das Teilchenwachstum zunehmend die Polymerisationsreaktion an Bedeutung gewinnt. Aggregative Stabilität wird nach dem Modell für einen Teilchengrößenbereich erhalten, der sich in Übereinstimmung mit experimentellen Daten aus der Fachliteratur befindet. Die berechneten Teilchengrößen entsprechen ebenfalls den in der Literatur publizierten experimentellen Werten, so daß das Modell eine gute Grundlage für die Beschreibung einiger morphologisch bestimmter Polymereigenschaften bildet.
Effect of concentration and temperature on the electrical conductivity of butyl rubber loaded with different types of carbon black
Authors: Eatah A. I. , Ghani A. A. , Hashem A. A. 
Published: April 2003

AbstractIn this study we are interested in the effect of concentration and temperature on the electrical resistivity of butyl rubber (IIR) loaded with two types of carbon black, (namely, high abrasion furnace black (HAF), and fast extrusion furnace black (FEF)). It was found that the conductivity at low carbon black concentrations is mainly achieved by thermal activation of carriers. Tunneling mechanism at low termperature followed by thermal activation at relatively high temperature is found to be predominant for moderate concentrations for both carbon blacks. The metal‐like behaviour which was observed in highly loaded compounds was attributed to both, the thermal expansion of the tunneling paths between carbon‐carbon agglomerates and the breakdown of carbon agglomerates with temperature.
Synthesis of halogenated phenyl glycidyl ethers and their use for flame retardancy of polymeric materials
Authors: Horák Oldřich , Eichler Josef , Dufek Jan , Melichárek Jan 
Published: April 2003

AbstractThis study deals with the synthesis of halogenated derivatives of phenyl glycidyl ether and with possibilities of their use as flame retardants and reactive diluents of epoxy resin.The best reaction conditions optimized by Nelder‐Mead simplex method were found. The products of very high quality were prepared. They were mixed with a lowmolecular epoxy resin and cured by diamino diphenyl methane.The viscosity of the resin mixtures and limiting oxygen index of cured systems were determined. It was found that a higher content of halogen, both chlorine and bromine, causes increasing viscosity and reduced flammability of the epoxides.
The characterisation of the polyethylene‐polystyrene‐divinylbenzene interpolymer cation‐exchange membranes in the electrolysis of borax solutions
Authors: Erbil H. Yildirim , Baysal Bahattin M. 
Published: April 2003

AbstractThe synthesis and the characterization of the PE‐PS‐DVB interpolymer cationexchange membranes in the electrolysis of borax solutions to produce boric acid and sodium hydroxide simultaneously was carried out. The characterization of the teflon based “Nafion 324” and polystyrene‐DVB based “Permaplex C‐20” membranes was also performed in the same system for comparison.The DVB contents were varied between 3 – 12% (by wt. in total monomers) and the increase of the cross‐links resulted in the decrease of the water contents and ionexchange capacities of the membranes. The PE present in the membrane acted as a barrier for electroosmotic water transport. The membranes with high DVB contents showed better electrolysis performance due to their low water contents and low electroosmotic water transport properties. The use of the interpolymer membrane containing 11.6% DVB resulted in high current efficiency and high sodium cation dynamic transport number and worked satisfactorily at the process conditions of borax electrolysis.
Functional monomers and polymers, 163. Inclusion polymerization of cyclic diene monomers in deoxycholic acid canals
Authors: Tsutsumi Hiromori , Miyata Mikiji , Takemoto Kiichi 
Published: April 2003

AbstractInclusion polymerization of cyclic diene monomers, such as cyclopentadiene, 1,3‐cyclohexadiene, 1,3‐cycloheptadiene, 1,5‐cyclooctadiene, and 2,5‐norbornadiene, was studied, using deoxycholic acid (DCA) as the canal component.The formation of monomer‐DCA adducts was observed, however, the polymerization occurred only in the case of cyclopentadiene, 1,3‐cyclohexadiene, or 1,3‐cycloheptadiene. The polymers obtained consisted preferably of 1,4‐units and almost 100% of 1,4‐units in the case of 1,3‐cyclohexadiene. ESR measurements revealed that inclusion polymerization of cyclopentadiene or 1,3‐cyclohexadiene in DCA canals proceeds by a free radical mechanism.
Interpenetrating polymer networks from castor oil and dibasic acids
Authors: Shah Tarulata B. 
Published: April 2003

AbstractPrepolyesters were obtained from castor oil and dibasic acids, viz oxalic, malonic, succinic, glutaric, adipic, suberic and sebacic acid. These prepolyesters (PPE) were subsequently interpenetrated with methyl methacrylate containing 1% ethylene glycol dimethacrylate as crosslinker by radical polymerization initiated with benzoyl peroxide. The novel PPE poly(methyl methacrylate) PPE/PMMA interpenetrating polymer networks (IPNs) were obtained as powder. They were characterized by solubility behaviour, IR spectral study and thermal behaviour.
Studies of reactions with polymers, IV. Syntheses and properties of poly(vinyl alcohol) graft terpolymers containing imide side chains
Authors: Chiang Wen‐Yen , Hu Chun‐Min 
Published: April 2003

AbstractA series of new poly(vinyl alcohol)‐g‐methyl methacrylate/N‐substituted maleimide graft terpolymers were prepared by reacting the residual anhydride groups on the poly(vinyl alcohol)‐g‐methyl methacrylate/maleic anhydride with the appropriate N‐substituted amines through the poly(vinyl alcohol)‐g‐methyl methacrylate/N‐substituted maleamic acid intermediate. Here, the N‐substituted amines were N‐benzyl, N‐butyl, N‐octyl, N‐dodecyl and N‐ethylol amines. The compositions and the proposed structure of the resultants were determined by elemental and infrared analyses. The water content, thermal and mechanical properties of the new poly(vinylalcohol) graft terpolymers were also investigated.
Synthèse de copolymères multiséquencés comportant des séquences cristallines organosiliciques
Authors: Schmitt D. , Beinert G. , Zilliox J. G. , Herz J. 
Published: April 2003

AbstractDes copolymères multiséquencés comportant des séquences cristallisables de poly(diméthylsilyl‐1 diméthyléthylènesilyl‐4 benzène) et des séquences, soit de polystryrène (PS), soit de poly(oxyéthylène) (POE), ont été préparés par réaction d'hydrosilylation entre polymères précurseurs, α,ω‐difonctionnels. Le polymère organosilicique utilisé portait des fonctions diméthylsilane aux deux extrémités de sa chaîne. Les polymères précurseurs PS et POE étaient dotés aux deux extrémités de leur chaîne de fonctions silvinyliques portées par un motif chimique de même nature que celle de l'unité monomère de la séquence organosilicique. Dans des conditions expérimentales adéquates, la réaction d'hydrosilylation conduit alors à des copolymères multiséquencés comportant 6 à 10 séquences.