bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transport phenomena in the system ion‐exchange membranes/sulfuric acid solutions. Non‐equilibrium thermodynamic approach
Authors: Ceynowa Józef 
Published: April 2003

AbstractTransport processes in the systems sulfonic acid membranes (NAFION‐120 or MRF‐26)/sulfuric acid solutions are discussed applying non‐equilibrium thermodynamic approach.For this purpose the phenomenological resistance and friction as well as coupling coefficients were calculated. The coefficients were extended to all the components, i.e. hydrogen ions, sulfuric acid anions, water, and polymer network.As the most important feature determining transport phenomena, the interaction between anions and the polymer network, having a maximum at the same relative concentration of sorbed acid to that of fixed charges in both membranes, was recognized.The second factor is the specificity of hydrogen ions, resulting in a small interaction of those ions with the polymer network, as well as essential coupling of large hydrogen ions and water streams.
Influence of different water soluble polymers and poly(ethylene oxide)/ionene complexes on sedimentation of suspended particles and filter cake resistance
Authors: Bortel Edgar , Stysło Maria 
Published: April 2003

AbstractThe objective of the investigations was to compare flocculating properties of three different water soluble resins: poly(ethylene oxide), PEO, with molecular mass Mv = 3.94 · 106 g/mol; polyacrylamide, PAAm, Mv = 2.1 · 106 g/mol, and tetramethyl‐2,6‐ionene bromide, ionene, Mw = 1500 g/mol. In each case the Healy‐La Mer theory proved to be valid due to the appearence of maximum points on both the subsidence w vs. polymer concentration c, and acceleration aQ vs. c curves. The ratios of these maximum values determined on aluminium silicate suspensions are as follows:

Contrary to aluminium silicate suspension dispersed TiO2 particles are not flocculated by PEO, although zeta potentials in both cases were found to be close up to each other, i.e. −16.68 and −16.38 mV, respectively. Nonetheless, the investigations carried out revealed the possibility to convert the high molecular weight PEO from being a stabilizer of the TiO2 suspension into a flocculant by means of interpolymer complexation with the ionene, i.e. a polyammonium salt. The ratios of maximum values related to complexes prepared with different unit mole ratios (u.m.r., values indicated in parantheses) are as follows:

and

Values at u.m.r. = 0 refer to uncomplexed PEO and at u.m.r. = ∞ to the uncomplexed ionene, respectively.
Effect of addition of sepiolite on the mechanical properties of glass fiber reinforced polypropylene
Authors: Acosta J. L. , Morales E. , Ojeda M. C. , Linares A. 
Published: April 2003

AbstractShort glass fiber reinforced polypropylene is one of the composites with the widest range of applications in the plastics industry. The partial replacement of the glass fibers by sepiolite, brings forth a hybrid composite with better mechanical properties and, as a result, enhanced compatibility and better interfacial adhesion as a consequence of the surface properties of the sepiolite. The results obtained are also interesting from a practical point of view, as they allow for considerable reductions in the costs of the formulation.
Corrections des réponses des détecteurs placés à la sortie d'un CPG
Authors: Benchabane Mahmed 
Published: April 2003

AbstractLe chromatographe par perméation de gel (CPG) muni du seul détecteur réfractomètrique est insuffisant pour la caractérisation des polymères. Une combinaison de trois détecteurs, un réfractomètre, un viscosimètre et un spectrophotomètre infrarouge, est nécessaire pour analyser un polymère présentant une hétérogénéité chimique et moléculaire. Malheureusement l'utilisation des réponses brutes de ces détecteurs conduit à des résultats erronés. Dans ce travail les différentes sources d'erreurs sont identifiées et puis corrigées.
Chemorheology of carboxyl terminated polybutadienes with different antioxidants
Authors: Schwartz Anders 
Published: April 2003

AbstractAn investigation of chemorheological properties has been made on two types of carboxyl terminated polybutadienes (CTPB), HC‐434, and Butarez CTL. Curing of CTPB has been done with an imine, MAPO. Films have been cast and cured and then cut into strips. Some of these strips have been extracted with acetone and then two types of antioxidants were added, phenyl‐beta‐naphthylamine (PBN) and methylenebis‐(4‐methyl‐6‐tert‐butyl)‐phenol (BKF). Continuous stress relaxation measurements and intermittent measurements of stress have been made at a temperature of 110°C. The results show that Butarez CTL seems to have better ageing properties than HC‐434 even when the same type of antioxidant has been added to the polymers. The most effective antioxidant of the two tested is BKF, which balances scission reactions and crosslinking reactions in a better way than PBN.
Studies on syntheses and permeabilities of special polymer membranes. 62. Active transport of alkali metal ions through poly(vinyl alcohol) membranes crosslinked with glutaraldehyde
Authors: Uragami Tadashi , Wada Tamaki , Sugihara Mizuho 
Published: April 2003

AbstractThe transport of alkali metal ion through poly(vinyl alcohol) crosslinked with glutaraldehyde without dissociating groups in a diaphragm cell, at one side being an alkaline and at the other an acidic solution, was investigated under various conditions. The active transport fraction of alkali metal ions from the alkaline side to the acidic side was significantly influenced by the degree of crosslinking of the membrane, size of anion species, initial pH on the acidic side, and the electric potential difference across the membrane.
An unexpected structure in the preparation of new epoxy resins
Authors: Serra Angels , Cádiz Virginia , Martínez Pedro‐Alberto , Mantecón Ana 
Published: April 2003

AbstractSpectroscopic data of epoxy resins, derivatives of pyromellitimide, have shown two types of attack on the two carbons of the oxirane group, giving rise to normal and abnormal opening of the ring. Thus, primary and secondary hydroxy groups were obtained. The physical characteristics of the obtained new polymers and also their solubilities are reported. Thermal analysis of these epoxy polyesterimides showed their good thermal properties.
Approximierung des verlaufes des monomerenumsatzes für einige fälle der lösungspolymerisationen
Authors: Matějíček Alois , Seidl Josef , Horký Jaroslav 
Published: April 2003

AbstractDie Approximierung des Umsatzkurvenverlaufs für einige Lösungscopolymerisationen im Batchverfahren wird mit Hilfe der empirischen Beziehung X = 1 − exp (−a1τa 2) durchgeführt. Die Übereinstimmung der gemessenen und berechneten Werte ist befriedigend. Aufgrund dieser Ergebnisse wird eine Methode der Approximierung des Umsatzverlaufs von Monomeren bei der semikontinuierlichen Copolymerisation vorgeschlagen. Sie geht von der Beschreibung der Copolymerisation im Satzbetrieb für dasselbe Reaktionssystem und dieselbe Reaktionstemperatur aus.Das mathematische Modell der semikontinuierlichen Copolymerisation beruht auf der diskreten Zuleitung des Monomerengemisches, wobei jedem Teil des der Reaktionsmischung zugeleiteten Gemisches der mit Hilfe der oben angeführten Gleichung beschriebene Umsatzverlauf zugeschrieben wird. Der Gesamtumsatz der Monomeren ist dann durch die Summe der Umsatzkurven einzelner differentieller Volumen des Monomerengemisches gegeben, die nach bestimmten Zeitintervallen der Reaktionsmischung zugeführt werden.
Preparation and chelating properties of polychalcones derived from 8‐hydroxyquinoline‐5‐aldehyde
Authors: Patel Hasmukh S. 
Published: April 2003

AbstractThe polychalcones designated as poly(7‐acetyl‐8‐hydroxyquinoline‐5‐aldehyde) (PAHQ) were prepared by Friedel‐Crafts (F.C.) acetylation of 8‐hydroxyquinoline‐5‐aldehyde (HQA) in nitrobenzene using AlCl3 as F.C. catalyst. The polycondensation was carried out in a single step and under different experimental conditions. It was shown that the most likely mechanism of the reaction is F. C. acetylation of HQA followed by condensation of the acetyl and aldehyde groups leading to polychalcones. The polychalcone samples, designated as PAHQ, were characterized by determining nitrogen and hydroxy content, by IR spectroscopy, by bromination reactions, by number average molecular weights, by viscometric study, and by thermogravimetry.Polymeric chelates of selected PAHQ polychalcone samples with various metal ions have been prepared and characterized. Ion exchanging properties of PAHQ polychalcones were also studied by employing the batch equilibration method.
Die oxidation von butadienstyrolkautschuk und daraus gewonnenem vulkanisat mit salpetersäure
Authors: Zaikova Stojanka , Bojadjiev Nikolaj , Bajdarov Dimiter 
Published: April 2003

AbstractIn vorliegender Arbeit wird die Reaktion zwischen Butadienstyrolkautschuk „Bulex‐1500”︁ (Handelsprodukt mit einem Gehalt von 25 bis 30% Styroleinheiten) bzw. Vulkanisat auf dessen Grundlage und Salpetersäure untersucht. Es wurde festgestellt, daß mehrere Reaktionsprodukte in meßbaren Mengen anfallen, nämlich aus Butadienstyrolkautschuk: Oxidierter Kautschuk, polyfunktionelles Oligomeres und Oxalsäure; aus dem Vulkanisat: Oxidiertes Vulkanisat, polyfunktionelles Oligomeres und Oxalsäure. Verfolgt werden die Reaktionsbedingungen der Oxidation von Kautschuk und Vulkanisat (Teilchengröße, Kontaktdauer, Temperatur) auf die Ausbeute an Reaktionsprodukten. Die Bedingungen für die Gewinnung der einzelnen Produkte mit optimaler Ausbeute werden angeführt. Weiterhin wird der Einfluß der Styroleinheiten des Butadienstyrolkautschukmoleküls auf die Ausbeute an Reaktionsprodukten untersucht. Die Ergebnisse werden mit den bei der Oxidation von Butadienkautschuk erhaltenen verglichen. Es wird festgestellt, daß die Oxalsäure das Produkt einer Reihe in dem salpetersauren Medium ablaufender oxidativ‐destruktiver Prozesse ist. Der Prozeßablauf wird in einem Schema veranschaulicht. Nachgewiesen wird, daß neben den oxidativ‐destruktiven Prozessen auch eine Nitrierung erfolgt. Es wird vorgeschlagen, die Reaktion zwischen Salpetersäure und Butadienstyrolkautschuk bzw. dessen Vulkanisat bei der Wiederverwendung von Kautschukabfällen einzusetzen.
Dielectric properties of styrene — butadiene rubber/silica mixtures
Authors: Louis N. Samson Maria , Banthia Ajit K. 
Published: April 2003

AbstractRice husk ash (RHA) obtained from rice mill and hydrated silica from RHA were used as a filler in vulcanized SBR 1502 and the dielectric properties were measured at a frequency of 1592 Hz at room temperature. The optimum hydrated silica content giving a good dielectric constant and conductivity was 125 parts/100 parts rubber and the dielectric loss was also high so that it could be a good insulater. There was no significant change in dielectric constant, dielectric loss and conductivity of SBR 1502 filled with RHA which could be used as high frequency dielectric due to low dielectric loss.
Copolymerization of acrylonitrile with N‐substituted maleimides
Authors: Sabaa Magdy W. , Mikhael Michael G. , Yassin Ahmady A. , Elsabeé Maher Z. 
Published: April 2003

AbstractAcrylonitrile was copolymerized with three N‐arylmaleimides as well as with N‐octadecylmaleimide in dimethylformamide (DMF) using azobisisobutyronitrile (AIBN) as initiator. The monomer reactivity ratios were calculated by the Fineman‐Ross and the Kelen‐Tüdős methods from which the Q‐ and e‐parameters of these monomers were evaluated. The prepared copolymers were characterized by viscosity measurements and thermal analysis. The intrinsic viscosity decreases by increasing the maleimide content in the copolymer. Thermogravimetry TG and differential thermal analysis (DTA) data showed a remarkable improvement in the thermal behaviour of the investigated copolymers. A mechanism for the participation of the maleimide units in the nitrile oligomerization was also proposed. The investigation of the dyeing properties of the copolymers with the exception of those containing octadecylmaleimide, showed good affinity towards basic dyes as well as an appreciable improvement in their colour fastness towards UV light.
DSC‐untersuchungen an PUR‐ionomeren aus zwei makrodiolen
Authors: Lorenz O. , Haulena F. 
Published: April 2003

AbstractDSC‐Untersuchungen wurden an Filmen aus Dispersionen von Polyurethan‐Ionomeren durchgeführt, zu deren Synthese zwei Makrodiole — Poly(tetramethylenoxid), Poly(propylenoxid) oder Polyester — Verwendung fanden. Das Mischen der beiden Komponenten erfolgte vor der Prepolymerherstellung, der Kettenverlängerung oder der Dispergierung, außerdem durch Verschnitt von zwei Latices aus jeweils einem Makrodiol.Filme aus Latexmischungen ergaben immer ein zweiphasiges Weichsegment. Dies bestätigt, daß die Identität der Latexteilchen bei der Filmbildung erhalten bleibt. Unabhängig davon, ob die Makrodiole oder die entsprechenden NCO‐Prepolymeren miteinander mischbar waren, bildeten Mischungen aus den Ionomeren zweiphasige Weichsegmente. Dies spricht dafür, daß jeder Ionomertyp eine Sorte Latexteilchen bildet.
Polycarbonate mit dimerfettsäure‐polyester‐segmenten
Authors: Dhein R. , Nerger D. , Schreckenberg M. , Morbitzer L. , Nouvertné W. 
Published: April 2003

AbstractDie Herstellung von neuen segmentierten Polykondensaten aus Dimerfettsäure‐Polyestern und Bisphenol A‐Polycarbonat wird beschrieben. Es werden Synthese und molekularer Aufbau der durch Kondensation in homogener Phase und in der Phasengrenzfläche hergestellten Produkte diskutiert. Die physikalischen Eigenschaften wie u. a. die Phasentrennung der Komponenten und anwendungsorientierte mechanische Festigkeitswerte, Wärmeformbeständigkeit und Spannungsrißkorrosion werden dargestellt. Die neuen Materialien zeichnen sich durch sehr gute Kälteflexibilität und hohe Wärmeformbeständigkeit aus.
The study of modified poly(styrene‐co‐divinylbenzene) by inverse gaschromatographic analysis
Authors: Sanetra Roman , Kolarz Boźena N. , Włochowicz Andrzej 
Published: April 2003

AbstractFor modified poly(styrene‐co‐divinylbenzene) the changes in supermolecular structure resulting from diluting the monomers during copolymerization with various amounts of inert diluents were studied. It has been found that the copolymers, obtained in the presence of substantial amounts of diluent, have a looser structure than those obtained with less diluent, as suggested by both the swelling measurements and the results of the inverse gas chromatographic (IGC) analysis. By this latter method it was found that the looser the copolymer structure, the broader was the range of adsorption‐absorption nonequilibrium region and the lower was the heat of adsorption of normal aliphatic alcohols by the copolymers. Since the copolymers had the same crosslinking degree, no difference in their apparent glass transition temperatures were detected.
Bestimmung der hydroxygruppen in oxycellulose
Authors: Franc Jaroslav , Černý Pavel , Blaha Jan 
Published: April 2003

AbstractEs wurde eine Methode für die Bestimmung des Hydroxygruppengehalts in Oxycellulose ausgearbeitet. Die Methode beruht auf der Abspaltung von Chlorwasserstoff bei der Reaktion der Hydroxygruppen mit 3,5‐Dinitrobenzoylchlorid in inerter Atmosphäre bei höheren Temperaturen. Die Menge des abgespaltenen gasförmigen Chlorwasserstoffs wird in einem Azotometer bestimmt.
Bestimmung der zusammensetzung von copolymeren bei der mehrstufigen chargenweisen polymerisation durch modifizierung der Mayo‐Lewis‐Gleichung
Authors: Matějíček Alois , Horký Jaroslav 
Published: April 2003

AbstractDie Bestimmung der Copolymerzusammensetzung bei der mehrstufigen chargenweisen Polymerisation mit Hilfe der Mayo‐Lewis‐Gleichung durch schrittweise Integration der entsprechenden Differentialgleichungen wird vorgestellt. Die Verwendung von zwei voneinander abhängigen Beziehungen für den Monomerumsatz, und zwar für den aktuellen sowie für den Gesamtumsatz, stellt eine Grundlage der vorgeschlagenen Methode dar. Der Integrationsschritt bleibt für die ganze Berechnung konstant. Das Ergebnis des angeführten Vorgangs ist ein Berechnungsschema für die Simulierung des Verlaufs einer mehrstufigen chargenweisen Polymerisation. Es ermöglicht, die Zusammensetzung der entstehenden Copolymeren annähernd zu berechnen. Die vorgeschlagene Berechnungsmethode wird anhand einer mehrstufigen chargenweisen Polymerisation des Gemisches Styrol/Ethylacrylat demonstriert.
Preparation and reactivity of new 3,3′,4,4′‐tetracarboxybenzophenone dianhydride glycidyl ester derivatives
Authors: Serra Angels , Cádiz Virginia , Martínez Pedro‐Alberto , Mantecón Ana 
Published: April 2003

AbstractNew diimidediacids coming from 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride (TBPA) and their corresponding diglycidyl derivatives have been synthesized. Preparation of diglycidyl esters was carried out by reaction with epichlorohydrin (EPC) in excess and using a quaternary ammonium halide as catalyst. The obtained compounds were characterized by spectroscopic methods and employed as starting monomers in a stepwise polymerization. The presence of imide groups in the new epoxy resins confers them higher thermal stability and also acceptable processing possibilities, as they are soluble in high polar organic solvents.
Studies on oxidation of precursor carbon fibres of petroleum pitch by gas chromatography
Authors: Sanetra Roman , Włochowicz Andrzej , Wysocki Marian 
Published: April 2003

AbstractVolatile products of precursor carbon fibres of petroleum pitch oxidized in oxygen were investigated.Concentration changes in CO, CO2, and H2O as a function of temperature and oxidation time were determined quantitively by gas chromatrography. The oxidation of precursor pitch fibres is the most efficient in the temperature range between 453–498 K during 2–4 hours.
Chemorheology of carboxyl terminated polybutadienes. Effect of ammonium perchlorate
Authors: Schwartz Anders 
Published: April 2003

AbstractAn investigation has been made on chemorheological properties of carboxyl terminated polybutadienes (CTPB) with addition of small amounts of ammonium perchlorate (AP). Curing of the polymers has been done with the imine tris‐[1‐(2‐methyl)‐aziridinyl]phosphine oxide (MAPO), and with mixtures of MAPO and epoxides. AP has been dissolved in MAPO before addition to CTPB. Continuous stress relaxation measurements and intermittent measurements of stress have been made at 110°C on CTPB cured with MAPO and at 80, 88, 100, and 110°C on CTPB cured with MAPO and epoxides. The results show that AP increases the rate of scission reactions in all compositions. Mixtures of MAPO and epoxides as curing agents give better properties to CTPB than only MAPO as curing agent.
Curing of carboxyl terminated polybutadiene with epoxide. Effect of additives
Authors: Schwartz Anders 
Published: April 2003

AbstractAn investigation has been made of curing of carboxyl terminated polybutadiene with the epoxide EPON 812 and with a chromium chelate as catalyst. The effect on curing of some additives, ammonium perchlorate (AP) and boron, has been measured at three temperatures 323, 343, and 363 K. The results show that the polymer without additive and with AP cures very well. Addition of boron to the polymer decreases the curing reaction. Addition of boron and AP together inhibits the curing reaction almost completely.
Studies on carboxymethyl cellulose. Quantitative analysis of the huggins constant k′
Authors: Trivedi H. C. , Patel R. D. 
Published: April 2003

AbstractThe Huggins constant k′ was measured for sodium carboxymethyl cellulose (NaCMC) solutions by an isoionic dilution technique for various ionic strengths. The value of k′ is found to increase with decreasing ionic strength. The electrostatic potential at the effective surface of the macromolecule was calculated due to the method of Mason et al. and that of Lifson and it has been observed that there is an agreement between the two methods of deriving the potential.
Electrical properties of pre‐extended FEF carbon black loaded rubbers
Authors: Amin M. , Nasr G. M. , Khairy S. A. , Ateia E. 
Published: April 2003

AbstractThe electrical conduction was investigated in different rubber composites, subjected to various values of longitudinal extension. The study involves styrene‐butadiene‐rubber (SBR), butadiene‐rubber (BR), acrylonitrile‐butadiene‐rubber (NBR), butyl‐rubber (IIR), and natural rubber (NR). Each type was separately blended with 100 phr of fast extruding furnace black. The parameters of the model of Polley and Boonstra are recalculated for a specific example and good fitting is found.
Veränderung von fluorpolymeren durch gammastrahlen
Authors: Orth Helmut 
Published: April 2003

AbstractFolien von Poly(tetrafluorethylen) (PTFE) und Poly(ethylen‐co‐tetrafluorethylen) wurden in Gegenwart von Luftsauerstoff der Einwirkung von Gammastrahlen ausgesetzt. Die IR‐analytische Untersuchung nach der MIR‐Technik (multiple innere Reflexion) zeigt, daß bei PTFE nur Kettenspaltung eintritt; eine oxidative Veränderung konnte nicht festgestellt werden. Die thermomechanische Analyse (TMA) zeigt, daß die Glasübergangstemperatur durch die Bestrahlung sinkt, offenbar als Folge einer Dichtezunahme der amorphen Phase. Im Gegensatz dazu unterliegt Poly(ethylen‐co‐tetrafluorethylen) einer Oxidation mit Ausbildung von Carbonylgruppen bis zu einer Strahlendosis von etwa 3 · 106 Gy, danach erfolgt Kettenabbau. Die Bildung der Carbonylgruppen ist eine Reaktion der ersten Ordnung.
Studies on some properties of poly(phenylene sulphide)
Authors: Kreja Ludwik , Warszawski Andrzej , Czerwiński Wojciech 
Published: April 2003

AbstractPoly(phenylene sulphide) was synthesized by a direct method. Benzene and elemental sulphur were used as substrates, and aluminium chloride as a catalyst. The obtained final product was characterized by IR, VIS‐UV, wide angle X‐ray and mass spectroscopy, thermal, and elemental analyses. On the base of the analytical methods the molecular structure of the obtained polymer was discussed.
Continuous free‐radical polymerization of styrene in the stirred tank reactor: Effect of retarders
Authors: Kirchner K. , Rintelen T. 
Published: April 2003

AbstractThe influence of different retarders on the conversion and the molecular weight distribution of initiated styrene polymerization in a continuous stirred tank reactor (CSTR) was investigated. The retarders used were nitrobenzene, tert‐butylpyrocatechol (tBC) and tert‐butyl‐o‐quinone. The inhibition constant of the nitrocompound was taken from literature to test the mathematical model. For the other two substances the inhibition constant was determined experimentally. The effectiveness of tBC increases in the presence of oxygen. Our results indicate that oxygen transforms the normal alkyl radicals of the polymerization into peroxy radicals having a higher reactivity towards the retarder thus leading to an overall increase in efficiency.
Influence of atmospheric conditions on the properties of polyolefins
Authors: Peeva Lily B. , Tsveteva Vichra A. 
Published: April 2003

AbstractEmpirical relationships, describing the change in mechanical properties of polyolefins at natural ageing in a seaside climate at middle geographic latitudes are derived on the basis of experimental data collected in a long exposure period — more than 10 years. The empirical equations describe the experimental data with a good accuracy. A constant is introduced accounting for the period in which the properties remain unchanged (induction period). The empirical equations derived may be used in predicting the change in mechanical properties of the investigated polymers in outdoor applications.