bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water absorption characteristics of vinyl alcohol/vinyl propionate copolymers with different microstructure
Authors: Arranz F. , Sánchez‐Chaves M. , Gómez‐Moñux M. 
Published: April 2003

AbstractVinyl alcohol/vinyl propionate (VAL/VP) copolymers with different microstructure were prepared by two different methods, i.e. partial alkaline hydrolysis of poly(vinyl propionate) and by partial esterification of poly(vinyl alcohol). 13C‐NMR results show that vinyl propionate units have an alternating tendency in VAL/VP copolymers prepared by esterification and a block distribution in VAL/VP copolymers when they are prepared by hydrolysis. The water absorption characteristics of VAP/VP copolymers have been studied. VAL/VP copolymers with a block sequence distribution exhibit a higher water absorption ability as compared with VAP/VP copolymers with a random sequence distribution and similar chemical composition. These results can be interpreted considering the formation of intramolecular hydrogen bondings as well as due also to steric hindrances effects. Sodium salicylate release studies from VAL/VP copolymers show that release is faster in VAL/VP copolymers prepared by hydrolysis according to its higher swelling ability in water.
4,4′‐carbo(4,4′‐bismaleimido phenoxy)diphenyl silane: Synthesis and characterization
Authors: Varma I. K. , Chander K. , Anand R. C. 
Published: April 2003

AbstractThe paper describes the successful synthesis of silicon containing bismaleimide resin 4,4′‐carbo(4,4′‐bismaleimido phenoxy)diphenyl silane. The char yield of the bismaleimide resin in N2 atmosphere was found to be 55% at 800°C. Chain extension of bismaleimide with 4,4′‐diamino diphenyl sulfone reduced the char yield and thermal stability.
Mechanische eigenschaften von polyesterfasern bei kurzzeitiger beanspruchung, 3. Konstruktion von relaxations‐ und retardations‐masterkurven von polyester‐multifilamentgarn
Authors: Beier Manfred , Schollmeyer Eckhard 
Published: April 2003

AbstractVon Polyethylenterephthalat (PETP)‐Multifilamentgarnen mit unterschiedlicher thermischer Vorgeschichte wurden Kraft‐Dehnungs‐Kurven mit den Dehngeschwindigkeiten 0,1 bis 100 000%/s ermittelt. Diese lassen sich zu Relaxations‐ und Retardationskurven über sieben Zeitdekaden umrechnen. Durch Superponieren von Relaxationsfunktionen für unterschiedliche Dehnungen bzw. Retardationsfunktionen für unterschiedliche Fadenzugspannungen werden Relaxations‐ und Retardationsfunktionen bis 21 bzw. 13 Zeitdekaden bestimmt, die sich in vier Bereiche unterteilen lassen, denen folgende Strukturveränderungen zugeordnet werden können:

Bereich 1: sofort erholbare, quasielastische Deformation mit Relaxationszeiten kleiner 1 bis 10 s,
Bereich 2: irreversible Deformation, Verfestigung, mit Relaxationszeiten zwischen 10 und 105 s,
Bereich 3: elastisches Verhalten des physikalischen Netzwerkes mit Relaxationszeiten zwischen 105 und 107 s und
Bereich 4: Umbau und Zerstörung des Netzwerkes mit Relaxationszeiten zwischen 107 und 1016 s.
Application of a mathematical model for the polyesterification process based on mixtures of fumaric acid and adipic acid without catalyst
Authors: Simitzis Johannis 
Published: April 2003

AbstractThe production of unsaturated polyesters based on mixtures of fumaric acid and adipic acid for different proportions without added catalyst was studied. The progress of the polyesterification was followed by determining the amount of water produced during the reaction. The kinetic parameters (reaction order n, activation energy E, frequency factor k0) of the polyesterification were determined and it was found out that n = 3 in all cases, while E and k0 increased by increasing amount of fumaric acid in the initial mixture of the reaction. A mathematical model for the polyesterification based on the production parameters (e.g. the heating program) and on the kinetic parameters was used and very good correlation was found between the corresponding pair of curves of water produced during the polyesterification, which were determined experimentally and theoretically (by calculating). With regard to the properties of the final product it was found out that its viscosity and its slight yellow colour increased by increasing the amount of fumaric acid in the initial mixture of raw materials. General prospects for practical application of this method were also discussed.
Sphärische ionotrope gele carboxygruppenhaltiger cellulosederivate als trägermaterialien für biologische wirkstoffe, I. Struktur‐ und quellungsuntersuchungen an xerogelen aus carboxymethylcellulose und aluminiumionen
Authors: Heinze Thomas , Klemm Dieter , Winkelmann Heinz , Linß Werner 
Published: April 2003

AbstractUnlösliche sphärische Aluminiumcarboxymethylcellulose‐Xerogelpartikel werden durch partielle Trocknung ionotroper Gele hergestellt, die durch Eintropfen wäßriger Lösungen von Natriumcarboxymethylcellulose in vernetzende Aluminiumsalzlösungen entstehen. Das Quellvermögen der porösen und mechanisch stabilen Trägermaterialien, die von einer dichten Außenschicht umgeben sind, erhöht sich durch partielle Umwandlung von Carboxygruppen in die Natriumsalze; es verringert sich mit zunehmendem Gehalt an freien Säuregruppen und steigender Trocknungstemperatur.
Studies on a macromolecular dichloroamine — the N,N‐dichloro poly(styrene‐co‐divinylbenzene) sulphonamide
Authors: Bogoczek Romuald , Kociołek‐Balawejder Elzbieta 
Published: April 2003

AbstractStarting from a commercial sulphonate cation‐exchange resin via sulphonyl chloride and sulphonamide resins, a macromolecular dichloroamine with ca. 6 mmol of active chlorine per gram of resin was prepared. The conditions for its optimum preparation starting from poly(styrene‐co‐divinylbenzene)sulphonamide (poly(St‐Co‐DVB)SO2NH2) were stated. The possibility of iterated chlorination and dechlorination of the product was proved. Its stability in the range of 20–100°C, both in the dry state and in aqueous media, was determined. Moreover, its derivatographic examinations up to 1000°C were performed. Examples for the use of the macromolecular dichloroamine as a polymer supported reagent for chlorination, oxidation of several organic and inorganic species and water disinfection are given.
A study of CO2 and excimer laser treatments of poly(etheretherketone)
Authors: Occhiello E. , Garbassi F. , Malatesta V. 
Published: April 2003

AbstractCO2 and excimer laser (193, 248, 350 nm) treatments were performed on poly(etheretherketone) (PEEK). High fluence excimer laser irradiation induced efficient etching, mainly due to thermal effects. The irradiation with CO2 lasers and high fluence excimer lasers introduced limited changes in surface chemistry and morphology.Low fluence excimer laser irradiation, particularly at 193 nm and 248 nm, favored the occurence of photochemical phenomena. Surface chemical modifications leading to oxygen depletion and preferential elimination of the ketonic bridge were assessed. At the same time surface morphological alterations were found, diffraction effects led to cone‐like structures while the redeposition of heavy oligomers caused the formation of debris on the surface.
Electrochemical polymerization of pyrrole on a fabric
Authors: Chen Show‐An , Tsai Yuan‐Chien 
Published: April 2003

AbstractAn electrochemical method for polymerizing pyrrole on a glass fabric without using metal anode to give a polypyrrole/fabric composite is proposed. The glass fabric is precoated with a thin layer of polypyrrole polymerized by use of ferric chloride as oxidizing agent. Morphological change during the polymerization is also reported.
Effect of copolymers modifying PVC on its physical and mechanical properties and its UV‐radiation resistance, IX. Photodeformation of surface of pure PVC films and films containing MMA/MA and traces of cyclohexanone
Authors: Kamińska A. , Kamiński J. , Rozpłoch F. , Kaczmarek H. 
Published: April 2003

AbstractBy means of microscopic observation, the deformation of the surface of PVC films caused by 253.7 nm UV radiation was investigated. Numerous blisters and holes were formed by the gaseous photodecomposition products of the polymer.More apparent deformation of the films containing MMA/MA suggests that the photodecomposition of this modifier occurs with higher efficiency than that of PVC.MMA/MA copolymer is introduced into PVC films to improve the smoothness of their surface, but this modifier accelerates the deformation of this surface under UV irradiation. It was also found that traces of cyclohexanone in samples retard the photodecomposition of MMA/MA and accelerate this process in PVC.
Zur statistik des einbaus einer als regler in polyamid 12 verwendeten aliphatischen dicarbonsäure
Authors: Hartkopf Uwe , der Heyde Wolfgang Auf , Meyer Kurt 
Published: April 2003

AbstractAls Hartblöcke in Polyetherblockamiden werden durch Dicarbonsäuren stark geregelte Polyamide eingesetzt. Da die Säure in Hinblick auf das Schmelz‐ und Kristallisationsverhalten einen Störbaustein in der Kette darstellt und bei einem ausgeregelten Produkt jede Kette ein Säuremolekül enthält, ist es von Bedeutung zu wissen, wo in der Kette der Einbau erfolgt. Anders als bei monofunktionellen Reglern, wo der Regler stets ein Kettenende bildet, kann ein bifunktioneller Regler a priori auch statistisch im Inneren der Kette eingebaut werden. Dies führt zu einer viel stärkeren Störung, als wenn das Reglermolekül und das sowieso als Störstelle wirkende Kettenende zusammenfallen. Anhand adipinsäuregeregelter Oligoamide auf Basis von Laurinlactam wird kernresonanzspektroskopisch der Einbau des Reglers untersucht und mit Rechnungen verglichen. Es ergibt sich nur dann gute Übereinstimmung, wenn vorausgesetzt wird, daß der Einbau statistisch erfolgt und dabei mit gleicher Wahrscheinlichkeit für jede beliebige Stelle zwischen zwei Laurinlactambausteinen oder am Kettenende abläuft. Weitere Rechnungen verdeutlichen den Einfluß des Reglereinbaus auf die Größe des amorphen Anteils.
An investigation of the controlled release of diacetylfluorescein (DAF) from polymeric membranes
Authors: Xu Ping , Wang Shuhong , Greenberg David B. 
Published: April 2003

AbstractThe release kinetics of diacetylfluorescein (DAF) from the polymeric membranes has been studied. The polymeric membranes were made of polystyrene and polysulfone materials in a monolithic form. This work employed a fluorescence spectrophotometer to monitor the release rates by the hydrolysis of DAF at 25°C. The investigation exhibited that the release rates follow a zero‐order kinetic scheme. The effects of different loadings of DAF and acetone on the controlled release rates were also exploited.
Concerning the degree of polymerization when using initiators with two peroxide groups
Authors: Wittmer Paul 
Published: April 2003

AbstractIn radical polymerizations with bifunctional initiators, an increase in the degree of polymerization in a batchwise reaction is only achieved at relatively high initiator conversions. This is, however, always achieved at the expense of a major decrease in the absolute value of the rate of polymerization.In a polymerization in a continuous‐flow stirred tank reactor there are ranges in which the bifunctional initiator is superior. However, the polymers thus formed always have a polydispersity index different from the value obtained when using a monofunctional initiator.The considerations presented here apply to polymerizations with combination termination, without chain transfer. In polymerizations with disproportionation termination and/or greater chain transfer the differences when using two types of initiator are substantially less and under certain circumstances disappear completely.
Thermooxidation yellowing of aliphatic polyamides
Authors: Fromageot Dominique , Roger Agnès , Lemaire Jaques 
Published: April 2003

AbstractDuring the thermo‐oxidation at 90°C of unsubstituted or N‐substituted aliphatic polyamides, formation of products which absorb in the UV and visible regions is observed. These products are photo‐instable either at short wavelengths or at long wavelengths and their photo‐reactivity is wavelength dependent. These oxidized groups are identified as crotonized aldehydic groups (CH  CH)2 or 3 CHO similar to those formed in the photo‐oxidation at short wavelengths of aliphatic polyamides.
Untersuchungen des Reaktionsverlaufes und der Produkte der säurekatalysierten Reaktion von Phenolen mit Holzöl, 1. Phenol und Holzöl
Authors: Ziebarth G. , Singer K. , Gnauck R. , Raubach H. 
Published: April 2003

AbstractDie zur Herstellung modifizierter Phenolharze für Elektroisolierschichtpreßstoffe wichtige säurekatalysierte Reaktion von Phenol mit Holzöl wird mittels Gas‐ und Flüssigchromatographie, IR‐, 1H‐NMR‐, 13C‐NMR‐Spektroskopie sowie MS untersucht. Es wird festgestellt, daß Phenol durch Holzöl im Sinne einer Friedel‐Crafts‐Reaktion C‐alkyliert wird; am Holzöl reagieren nur die Doppelbindungen der Eläostearinsäure.
Untersuchungen des Reaktionsverlaufes und der Produkte der säurekatalysierten Reaktion von Phenolen mit Holzöl, 2. Vergleichende untersuchungen an verschiedenen phenolen
Authors: Singer K. , Ziebarth G. , Schulz G. , Gnauck R. , Raubach H. 
Published: April 2003

AbstractDie zur Herstellung holzölmodifizierter Phenolharze für Elektroisolierschichtpreßstoffe wichtige säurekatalysierte Reaktion von Phenolen mit Holzöl wird für 4 verschiedene Phenole (Phenol, o‐, m‐, p‐Cresol) vergleichend untersucht. Insbesondere durch 13C‐NMR‐ und IR‐Untersuchungen wird festgestellt, daß ausschließlich C‐Alkylierung des Phenols durch Holzöl im Sinne einer Friedel‐Crafts‐Reaktion abläuft. Die Reaktionsorte an den Phenolen werden ermittelt. Weiterhin werden die Geschwindigkeiten der Reaktion der Phenole mit den Eläostearinsäureresten verglichen.
Synthesis and impact behaviour of PMMA/EVA interpenetrated blends
Authors: Laurienzo Paola , Malinconico Mario , Ragosta Giuseppe , Volpe Maria Grazia 
Published: April 2003

AbstractIn the present work blends between poly(methylmethacrylate) (PMMA) and poly(ethylene‐co‐vinylacetate) (EVA) or its derivative EVA‐g‐succinic anhydride (EVA‐g‐SA) have been investigated by linear elastic fracture mechanics (LEFM) with Charpy impact tests and by scanning electron microscopy (SEM). Blends prepared by “insitu” radical polymerization of the acrylic monomer in the presence of the rubbers have an IPN morphology, while a blend prepared by melt‐mixing the polymer components shows the typical biphasic structure of rubbery domains dispersed in a glassy matrix.Furthermore, a different behaviour is found when using EVA‐g‐SA instead of EVA. A fair agreement is found between the response of the LEFM analysis applied to the results of Charpy impact tests and the observed morphologies.
Unvernetzte Epoxid‐Amin‐Additionspolymere, 21. Dimethyl(aminomethyl)phosphinoxid, ein comonomeres für epoxidpolymere mit verminderter entflammbarkeit
Authors: Klee Joachim , Hörhold Hans‐Heinrich , Schütz Heidrun , Varbanov Sabi , Borissov Gueorgui 
Published: April 2003

AbstractEs wird über die Herstellung von linearen, hochmolekularen Epoxid‐Amin‐Additionspolymeren und telechelen Prepolymeren berichtet, die mit Dimethyl(aminomethyl)phosphinoxid (DMAPO) ein flammwidriges Kettenglied in der Polymerkette enthalten. Die Struktur dieser Polymeren und Prepolymeren wird mittels Elementaranalyse, Mn‐Werten, IR‐, 1H‐NMR‐, 13C‐NMR‐ und 31P‐NMR‐Spektroskopie untersucht. Der Sauerstoffindex OI von DGEBA/DMAPO‐Polymeren erreicht etwa 30.Auch der polare Charakter von Epoxid/Amin‐Additionspolymeren, der für die Haftung an metallischen und oxidischen Werkstoffen bedeutsam ist, wird durch den Einbau von PO(CH3)2‐Gruppen verstärkt. Ebenso wird hierdurch die photooxidative Stabilität verbessert.
Some kinetic features of the initial stage of acid catalyzed polycondensation of furfuryl‐alcohol and formaldehyde, III
Authors: Szesztay M. , László‐Hedvig Zs. , Tüdös F. 
Published: April 2003

AbstractAccumulation of “dimers” and “trimers” considered to be inactive and consumption of active ones with reaction time in furfuryl‐alcohol (FA)/formaldehyde (F) acid catalyzed condensation system was proved by GPC technique using double detector.A reaction mechanism was proposed for the condensation process explaining some contradictions of investigations collected so far.
Weak acid ion exchange membranes
Authors: Gasperowicz Aleksandra , Poźniak Gryzelda , Trochimczuk Witold 
Published: April 2003

AbstractWeak acid ion exchange membranes were prepared by pressing methyl acrylate/methyl methacrylate and methyl acrylate/butyl methacrylate copolymers into the film form. Before shaping, the copolymers were hydrolysed in an alkaline solution (heterogeneous system). The following optimal hydrolysis parameters were established: temperature: 90°C; hydrolyzing agent potassium hydroxide/methylacrylate ratio: 5 mol/mol; concentrations: copolymer: 5 wt.‐%, emulsifier (Hostapal CV): 0.5 wt.‐%.Products insoluble in water or alkaline solutions, yet containing enough carboxylic groups to provide an ion exchange selectivity, were obtained by hydrolysis of copolymers containing less than 30 wt.‐% of methyl acrylate units.The ion exchange and transport properties (in the system 0.5 M NaOH//membrane//H2O) were found to be the best for the membranes obtained from hydrolysed poly(methyl acrylate‐co‐methyl methacrylate).
Polyamines containing β‐hydroxyurethane linkages as curing agents for epoxy resin
Authors: Rokicki Gabriel , Łaziński Robert 
Published: April 2003

AbstractA method of obtaining modified amine curing agents containing β‐hydroxyurethane linkages is presented. The basic physical and chemical properties of the modified polyamines, such as viscosity and reactivity towards epoxy resins, have been studied.A shortening of the gel and curing times in addition to a decrease of the exothermic effect accompanying the curing of an epoxy resin was found in comparison with the system containing an unmodified amine. Mechanical and thermomechanical studies showed a rise of the deflection temperature, hardness and strength features such as tensile strength, shear and peel strength for epoxy resins crosslinked with modified curing agents in comparison with those parameters obtained for resins crosslinked with the initial amines.
Functionalized polybutadiene oils as adhesion promotors for mineral fillers in rubber compounds
Authors: Haag Horst‐Günther , Herrmann Christoph , Kampf Wolfgang , Nordsiek Karl‐Heinz , Streck Roland , Zerpner Dieter 
Published: April 2003

AbstractThis paper deals with silylated and maleated polybutadiene oils and their effects in rubber compounds containing silica(tes) resp. chalk as fillers. They are shown to be efficient aids in the substitution of oil‐dependent carbon black by mineral fillers.
Study of thermal stimulated current and effect of annealing on cellulose nitrate
Authors: Mounir M. , Abd‐Eldaem A. 
Published: April 2003

AbstractThe investigated samples were cellulose nitrate CN‐85. The conductivity increases with temperature for unannealed samples and decreases with increasing time of annealing for annealed samples.The activation energy is equal for all samples and amounts to 2.1 eV in a temperature range from 322 to 385 K. The behaviour is metallic (dσ/dT) < 0 for times of annealing larger than 24 h. The TSC current was measured. The position of the maximum slightly shifted towards higher temperatures with increasing rate of heating. The activation energy in the case of the TSC current was 0.21 eV and independent of the rate of heating. The dipolar relaxation time and imaginary dielectric constant were calculated theoretically and studied as a function of temperature.
Modification of transport properties of ion exchange membranes, X formation of polyethyleneimine layer on cation exchange membrane by acid‐amide bond
Authors: Sata Toshikatsu , Izuo Ryuji 
Published: April 2003

AbstractIn order to give the monovalent cation permselectivity to the cation exchange membrane permanently, polyethyleneimine layer was formed on the membrane surface by acid‐amide bond between polyethyleneimine and the SO2Cl groups of a styrene‐divinylbenzene copolymer membrane. After the reaction, the SO2Cl groups remaining in the inner part of the membrane were hydrolyzed by immersing the membrane into an aqueous sodium hydroxide solution.The resultant cation exchange membranes were evaluated by electrodialysis of sea water from the point of view of the monovalent cation permselectivity, electric resistance of the membrane, current efficiency, and transport number of sodium ions calculated by membrane potential in connection with reduced viscosity of the various commercial polyethyleneimines, ATR‐IR measurements on the membrane surface suggested that the acid‐amide bond was stable for severe hydrolysis reaction.
Thermal and viscoelastic behavior of polyetheretherketone/polyethersulfone blends
Authors: Wu Zhongwen , Zheng Yubin , Yu Xiaomei , Nakamura Tomoki , Yosomiya Ryutoku 
Published: April 2003

AbstractThe polymer blends obtained by the solution blending method show a type of compatible polymer blends. The samples obtained by compression molding the polymer blends below the melting point of the polyetheretherketon (PEEK) exhibit dynamic viscoelastic behavior characteristic of compatible polymer blends, but those by compression molding above the melting point of the PEEK show a phase separation in dynamic viscoelastic behavior.
Epoxy groups on grafted polypropylene. I. Reaction with acids
Authors: Citovický P. , Chrástová V. , Beniska J. , Sedlář J. , Mejzlík J. 
Published: April 2003

AbstractEpoxy groups on isotactic polypropylene, to which 2,3‐epoxypropylmethacrylate was grafted, were reacted with low molecular carboxylic acids. The reaction proceeds under heterogeneous conditions in the presence of organic solvents and it may be catalysed by tertiary amines. The rate constants of this reaction are correlated with the dissociation constant of the bonded acid and with the character of the used catalyst. The reactivity of polymer‐bonded epoxy groups is not changed when comparing with reactions performed under homogeneous conditions.
Epoxy groups on grafted polypropylene. II. Reaction with amines
Authors: Citovický P. , Malík J. , Beniska J. , Chrástová V. , Sedlář J. 
Published: April 2003

AbstractEpoxy groups attached to isotactic polypropylene in form of 2,3‐epoxypropylmethacrylate grafts were reacted with low molecular secondary amines. Secondary heterocyclic amines exhibit high reaction rates in this process. The bonding of less basic amines is accelerated in the presence of acid catalysts. The mechanism is discussed of amine‐acid couple influence upon the epoxy group present in heterogeneous system on the surface of solid polymer.
A study of blends of poly(n‐octadecyl methacrylate) with n‐dodecane and n‐octadecane
Authors: Rubin Isaac D. , Pugliese Rocco D. 
Published: April 2003

AbstractDSC and X‐ray diffraction analysis were used to study blends of poly(n‐octadecyl methacrylate) with n‐dodecane and n‐octadecane crystallized from the melt to gain a better understanding of the interaction of comb‐like polymethacrylates with paraffin waxes. In both sets of blends both components could crystallize in separate lattices. However, the polymer interfered with the crystallization of the n‐paraffin, resulting in less crystalline paraffin than expected on the basis of blend composition. In the blends with n‐dodecane, evidence was found for partial cocrystallization of the paraffin and the polymer side chains. No cocrystallization was observed in the blends with n‐octadecane.