bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermoelektrische analyse (TEA), eine neue Methode zum gleichzeitigen Studium elektrischer und thermischer Eigenschaften von Polymeren
Authors: Weber Gunter , Vogel Burkhard 
Published: April 2003

AbstractEs wird eine neue Untersuchungsmethode für die gleichzeitige Beobachtung elektrischer und thermischer Eigenschaften von Polymeren dargestellt. Die thermoelektrische Analyse (TEA) verknüpft die bestehenden Techniken der DSC (oder DTA) mit der elektrischen Methode der thermisch stimulierten Entladung (TSD). TEA‐Untersuchungen wurden an Copolymeren von Methylmethacrylat (PMMA) oberhalb von Raumtemperatur durchgeführt. Während im DSC‐Signal unterhalb der Glastemperatur Tg des PMMA keine Veränderung zu beobachten ist, erkennt man im TSD‐Strom bei etwa 80°C das Aufterten einer Schulter (α2‐Relaxationsprozeß) auf der Tieftemperaturseite des α1‐Maximums (Tg). Da der TSD‐Strom linear mit dem Comonomergehalt im Bereich des α2 Relaxationsprozesses ansteigt, wird dieser der Desorientierung von kleinen, polaren Segmenten des Comonomeren in der Hauptkette des PMMA zugeschrieben. Das TSD ρ‐Maximum bei T>Tg kann auf in Haftstellen eingefangene Ladungsträger zurückgeführt werden. Die Ergebnisse lassen erkennen, daß die TEA‐Technik eine hohe Empfindlichkeit und Auflösung besitzt und durch ihre gleichzeitige Zuordnung thermischer und elektrischer Größen zu einer Vertiefung der Kenntnisse des elektrischen Leitungsmechanismus und zum Erkennen und Deuten von Relaxationserscheinungen in Hochpolymeren beiträgt.
Effects of molecular weight and molecular weight distribution of polyester based soft segments on the physical properties of linear polyurethane elastomers
Authors: Lunardon Gianflavio , Sumida Yuzo , Vogl Otto 
Published: April 2003

AbstractLinear polyurethane elastomers were synthesized in dimethyl acetamide (DMAc) solution, starting from 4,4′‐methylene diisocyanate 1,4‐butanediol, and polyester diols of two different molecular weights (MW) and each with a series of molecular weight distributions (MWD). Diol samples of various MWD's were prepared by blending polyesters of different MW. Polyurethane elastomer films were cast from solution, and characterized with the effect of the molecular weight and molecular weight distribution of the polyester diols on the physico‐mechanical and morphological properties of the polyurethane elastomers investigated. Most properties studied depended strongly on the MW of polyester soft segments; the MWD influenced primarily the relaxation behaviour of the polyurethane samples. Our data indicates that these phenomena are related to variations of the amounts of high MW polyester diols. The dynamic‐mechanical measurements and the polymer morphology studies indicate that a diffuse, mixed amorphous phase exists in these polymers; the amount of the phase depends on MW and MWD of the polyester segment, but the intrinsic properties are essentially independent of the MWD of the polyester segment.
The cupric sulphate‐hydrazine hydrate system as an initiator for vinyl graft polymerization onto wool
Authors: El‐Rafie M. H. , Abdel‐Fattah S. H. , Khalil E. M. , Hebeish A. 
Published: April 2003

AbstractThe ability of the cupric sulphate‐hydrazine hydrate redox system to induce vinyl graft polymerization onto wool fibres was studied under different conditions. The magnitude of grafting is governed by concentrations of cupric ions, hydrazine hydrate and monomer as well as pH and temperature of the polymerization medium. Detailed studies were carried out on grafting of wool with methyl methacrylate though ethyl acrylate and styrene were also used. Cupric ions were also replaced by ferric ions in some experiments. Main conclusions arrived at from these studies are: (a) there are optimal concentrations of cupric ion and hydrazine hydrate, (b) the grafting reaction is more favoured at higher (pH higher than 7) than that at lower pH's (pH less than 5), (c) 70°C constitutes the optimal temperature for grafting, (d) the graft yield increases by increasing methyl methacrylate concentration, (e) replacement of cupric ion by ferric ion lowers the rate of grafting and (f) the highest graft yield is obtained with methyl methacrylate and the lowest with styrene.
Reactive polymers, XXVII. Kinetics of chemical reactions of metal ions with functional groups of glycidyl methacrylate — ethylenedimethacrylate copolymers modified by ethylenediamine
Authors: Švec F. , Kálal J. , Kálalová E. , Marek M. 
Published: April 2003

AbstractThe conditions were followed which influence the rate of uptake of Cu(II) and Ag(I) ions by a copolymer of glycidyl methacrylate with ethylene dimethacrylate modified by ethylenediamine. In addition to the particle size (0.1–1 mm) of the chelating resin, the concentration of cations in solution affects substantially the rate of sorption.It follows from the calculated rate of diffusion and from the rate constants of the chemical reaction that the reaction kinetics is decisive for particles below 0.1 mm, whereas with increasing particle size the inner diffusion begins to play a more important role and becomes finally the rate‐determining mechanism. The obtained results are supported by observations of morphology.
Reactive polymers, XXVIII. Modification of hydrolysed glycidylmethacrylate — ethylenedimethacrylate copolymers by propane sultone
Authors: Ribeiro C. M. A. , Hradil J. , Švec F. , Kálal J. 
Published: April 2003

AbstractMacroporus reactive polymers based on glycidylmethacrylate and ethylenedimethacrylate were modified so as to contain more than one mmol g−1 of sulfonic acid groups. This modification consists in the introduction of hydroxyl groups, by hydrolysis of the epoxy groups of the reactive polymers, and in its subsequent etherification by treating with propane sultone in aqueous sodium hydroxide medium. The effect of changing reaction conditions on the extent of chemical modification and on pore structure was studied in detail. The yield of sulfopropylation depends mainly on the sodium hydroxide concentration and on the surface area of the macroporous polymeric matrix.
Photoabbau von PVC‐Folien. III. Einfluß von Wärmestabilisatoren
Authors: Braun Dietrich , Kull Stefan 
Published: April 2003

AbstractEs wurden PVC‐Filme mit variablen Konzentrationen an Wärmestabilisator (Dioctylzinn‐bis‐(thioglykolsaureisooctylester)) unter Stickstoff und Luft mit einer Quecksilberhochdruckdampflampe bestrahlt. Die HCl‐Abspaltung und die Verfärbung wurde messend verfolgt.Die Hauptfunktion des Stabilisators besteht in der Unterdrückung der Bildung langwelliger Absorptionen. Man findet auch Hinweise auf eine direkte Beteiligung des Sta‐bilisators an der Photoreaktion.
Untersuchung zur Flockungsfähigkeit von Polyacrylamid‐co‐acrylaten (0 – 100 mol‐% Acrylamid)
Authors: Kulicke W.‐M. , Kniewske R. , Hörl H.‐H. 
Published: April 2003

AbstractDie Flockungsaktivität von Polyacrylsäure, Polyacrylamid‐co‐natriumacrylaten und Polyacrylamid, die in unserem Labor hergestellt wurden, wurde untersucht. Polyacrylamid zeigt mit zunehmendem Molekulargewicht einen Anstieg der Flokkungsgeschwindigkeit. Die wälßrigen Polyacrylamidlösungen wie auch die im festen Zustand gelagerten Proben mit Mη ≥ 1,5 · 106 g/mol unterliegen einem zeitlichen Abfall des Staudinger‐Index bei gleichzeitiger Abnahme der Flockungsgeschwindigkeit. Parallel dazu beobachtet man ein Absinken des Trägheitsradius. Diese zeitabhängigen Phänomene werden durch einen Konformationswechsel in der Molekülstruktur und nicht durch Kettenbruch verursacht.Lineare Polyacrylamide besitzen bessere Flockungseigenschaften als verzweigte (20 Zweige) mit dem gleichen absoluten Molekulargewicht. Polyacrylamid‐co‐natrium‐acrylate zeigen bei einem Comonomerengrad von ca. 70 mol‐% Acrylat ein Maximum der Flockungsaktivität.
Cationic cyclization of cis‐1,4‐polybutadiene I. Synthesis and technological evaluation of the polymer
Authors: Priola A. , Bruzzone M. , Mistrali F. , Cesca S. 
Published: April 2003

AbstractControlled cyclization of cis‐1,4‐polybutadiene‐rubber (BR) was achieved with the aid of cationic catalyst systems based on alkyl aluminium chloride and organic halide and by working in xylene solution at high temperature (T > 100°C). Different catalysts based on some Lewis acids and the main parameters of the cyclization process were investigated. Interesting gel‐free elastomers were obtained when 35–40% of the initial unsaturations disappeared.Physical and technological properties of cyclized BR revealed that a new class of elastomers was obtained displaying skid resistance and tensile properties better than those of the parent polymer. The results were accounted for in terms of polycyclic sequences randomly formed in BR chains during the cyclization process.
An synthesepulp immobilisierte enzyme, II
Authors: Vogt Hans‐Günter , Manecke Georg 
Published: April 2003

AbstractMit Polyvinylalkohol‐haltigem Synthesepulp wurden Derivatisierungsreaktionen durchgeführt, die die Einführung folgender reaktiver Gruppen gestatten: Der Isothiocyanat‐, Imidocarbonat‐ und der Dichlor‐s‐triazin‐Gruppe. Weiterhin ließen sich gemischte Disulfide mit 2‐Thiopyridin‐Resten als reaktiver Komponente herstellen. Die Glutardialdehyd‐Methode wurde zur Aktivierung des unmodifizierten Synthesepulps und auch von Aminogruppen‐haltigen Derivaten dieses Polymeren herangezogen. An allen hier beschriebenen reaktiven Trägern ließen sich Enzyme immobilisieren. Als Enzyme wurden Trypsin, Esterase (aus Bacillus subtilis), Glucose‐Oxydase, Urease, Katalase, Hexokinase und Glucose‐6‐phosphat‐dehydrogenase eingesetzt und die Immobilisierungsprodukte charakterisiert.
The effectiveness of some commercial emulsifiers in emulsion polymerization I. “Soap‐free” systems, ethoxylated nonylphenols
Authors: Šňupárek Jaromír 
Published: April 2003

AbstractThe initial polymerization rate of ethyl, butyl, and 2‐ethylhexyl acrylate was studied in a thermally insulated polymerization reactor. Monomers were continuously added into the reactor and the effect of variables in emulsifier and initiator concentrations was investigated. Ethyl and butyl acrylate polymerized even in absence of emulsifier. This indicated a homogeneous nucleation of particles. Ethoxylated nonyl‐phenols containing 20 and more oxyethylene units were effective in emulsion polymerization of the studied acrylic monomers.
The effectiveness of some commercial emulsifiers in emulsion polymerization II. Anionic types
Authors: Šňupárek Jaromír 
Published: April 2003

AbstractThe initial polymerization rate of ethyl, butyl, and 2‐ethylhexyl acrylate was studied in a thermally insulated polymerization reactor. The monomers were continuously added into the reactor and the effect of concentration of anionic emulsifiers on the temperature increase was investigated.Alkyl(aryl)polyethylenglykolethersulfate were found to be most effective in promoting the initial polymerization rate. An inhibition action of some emulsifiers was found.
Polyurethanes from betulinol
Authors: Erä Väinö A. , Jääskeläinen Pirjo , Ukkonen Keijo 
Published: April 2003

AbstractPolyurethanes were synthesized by polyaddition reaction of betulinol isolated from birch bark and linear extended aromatic polyisocyanate Desmodur E 22. The reactions were carried out in solvents such as toluene and cyclohexanone, and the polymers with molecular weights of up to 7200 g/mol were obtained. The kinetics of the reaction was studied and the formation of polyurethanes was shown by IR‐spectroscopy. The structure of the polymers was determined from the molecular characteristics of the building units.
Graft copolymerization of vinyl monomers on modified cottons, part XVII. Continuous and semi continuous methods for grafting of partially carboxymethylated cotton with acrylamide
Authors: Hebeish A. , El‐Rafie M. H. , Abdel Bari E. , El‐Hussini A. 
Published: April 2003

AbstractSemi continuous and continuous methods were described for grafting of acrylamide to partially carboxymethylated cotton (PCMC). In essence, PCMC previously treated with ferrous sulphate was padded in a solution containing acrylamide and H2O2 followed by drying and baking. Incorporation of N‐methylol finishing agent to the polymerization solution brought about easy care cotton with improved strength properties and good fabric performancy as measured by crease recovery.
Polymerization of lactams, 38. Copolymerization of 6‐caprolactam with some of its non‐homopolymerizing derivatives
Authors: Kondelíková Jaroslava , Šejba Jan , Králíček Jaroslav , Smrčková Zdena 
Published: April 2003

AbstractIt was demonstrated that non‐homopolymerizing derivatives of 6‐caprolactam: 7‐cyclohexyl‐1‐aza‐2‐cycloheptanone (I) and 7‐isopropyl‐5‐methyl‐1‐aza‐2‐cycloheptanone (II) were polymerizing with 6‐caprolactam under conditions of the socalled hydrolytic polymerization. With its increasing content in the initial reaction mixture the copolymerization rate, the equilibrium content of the copolymer, and the reduced viscosity decreased. Lactam (I) was a more reactive comonomer in comparison with lactam (II).
Chemistry and application of organic isocyanates IV. Conversion of hexamethylene diisocyanate into biuret derivatives by means of Na2SO4· 10 H2O
Authors: Lesiak Tadeusx , Czerwiński Wojciech , Balewski Andraej 
Published: April 2003

AbstractThe attempts of hexamethylene diisocyanate (HDI) conversion by means of Na2SO4· 10 H2O at 120°C to 160°C at different molar ratios of reactions of reactants have been described. It has been shown that in this process apart form N,N′,N″‐tris(6‐isocyanatohexyl)biuret there are also formed biuret derivatives of higher molecular weight. Due to the application of mass spectrometry analyses and gel permeation chromatography the scheme of formation of prepolymers having the biuret structure of molecular weight up to 1300 has been proposed.
Dyeing of chemically modified cellulose, VIII. Behaviour of cellulose graft copolymers towards dyeing with different classes of dyestuffs
Authors: El‐Rafie M. H. , Bari E. M. Abdel , El‐Hussini A. , Hebeish A. 
Published: April 2003

AbstractDyeing of partially carboxymethylated cotton having 30 meq./100 g cellulose before, after and during acrylamide graft copolymerization with some direct, reactive and acid dyes was investigated. The colour strength of the dyeings so obtained revealed that it is advantageous to carry out dyeing and grafting simultaneously. It is believed that (a) ionic repulsion between the negatively charged cellulose surface and the similarly charged dye ions is reduced in presence of acrylamide, (b) dyeing occurs before packing of the grafted polymer and cellulose, and (c) the dye molecules are partly enmeshed in the copolymer. The dyeing behaviour of partially carboxymethylated cotton grafted with poly(ethyl acrylate), poly(allyl acrylate), poly(methyl methacrylate) and polystyrene towards some disperse and cationic dyes was also studied. Regardless of the copolymers used, the colour strength was quite high. However, the magnitude of the colour strength was determined by the amount and nature of the grafted chains and factors associated with both such as molecular weight, molecular weight distribution and frequency of branching as well as by the nature of the dye.
Hochfeld‐13C‐Kernresonanz am Polyacrylnitril
Authors: Neukam Theodor , Wendisch Detlef 
Published: April 2003

AbstractIn comparison to smaller frequencies at 90.52 MHz the methylene region of the carbon‐13 spectrum is split into signals corresponding to the configurational tetrads. Thus the carbon‐13 resonance at high fields enables the tacticity determination via all the three carbon atoms of polyacrylonitrile.
Die Messung der Dichte zur Detektion in der Gelchromatographie IV. Quantitative auswertung
Authors: Trathnigg Bernd 
Published: April 2003

AbstractIn dieser Arbeit wird der lineare Bereich eines densimetrischen Detektors nach der Biegeschwingermethode untersucht. Es wird gezeigt, daß Peaks leicht und mit guter Genauigkeit und Reproduzierbarkeit integriert werden können. Der Response des Detektors ist in dem bei der GPC in Frage kommenden Konzentrationsbereich linear, die Nachweisgrenze hängt von der Qualität des Thermostaten ab, ist aber grundsätzlich mit der eines Differentialrefraktometers vergleichbar.
Beiträge zur Galvanisierung von Polymeren, 1. Einfluß der chemischen Vorbehandlung auf Polymere aus Styrol und Butadien
Authors: Springer Jürgen , Sirinyan Kirkor , Sezi Recai , ToVinh Khuong 
Published: April 2003

AbstractDie klassischen Vorbeizen zur galvanischen Metallisierung von Polymeren aus Chromtrioxid, Schwefelsäure und Phosphorsäure wurden am Beispiel von Styrol‐Butadien‐Copolymeren durch Ozon ersetzt. Die Haftfestigkeit der galvanischen Metallschicht bei einem Butadiengehalt von 73% betrug ca. 12 N/25 mm. Der Oberflächenwiderstand der ozonisierten Copolymeren war > 2 · 1015 Ω. Die mit der Ozonisierung verbundenen chemischen und morphologischen Veränderungen wurden durch Molmassenbestimmung, IR‐Spektroskopie und Rasterelektronenmikroskopie verfolgt.
Isolierung und Charakterisierung von niedermolekularem Polyvinylchlorid
Authors: Braun D. , Holzer G. , Noriega R. I. 
Published: April 2003

AbstractUnter geeigneten Polymerisationsbedingungen wurde niedermolekulares PVC in CCl4 in Gegenwart von Isobutylen hergestellt. Beim thermischen Abbau der fraktionierten, festen Anteile aus dem Polymerisationsansatz nimmt die Abbaugeschwindigkeit mit abnehmendem Molekulargewicht zu. Bei Verwendung von Dicyclohexylper‐oxodicarbonat als Initiator gegenüber. Azoisobutyronitril verschlechtert sich die thermische Stabilität merklich. Die Substanzen mit dem niedrigsten Molekulargewicht wurden aus dem bei der Polymerisation verwendeten Lösungsmittel als farblose Flüsigkeit bei 90°C–110°C (10−4 Torr) destilliert. Es handelt sich hierbei jedoch nicht um PVC‐Homologe mit niedrigem Polymerisationsgrad; vielmehr konnte mit spektroskopischen Methoden nachgewiesen werden, daß der Hauptanteil des erhaltenen Germisches eine Verbindung ist, die aus der Kombination von Tetrachlorkohlenstoff und Isobutylen entsteht.
Wasserlösliche Polymer auf Acrylamidbasis, 1. Einfluß des Molekulargewichtes und des Hydrolysegrades auf die Sedimentationsgeschwindigkeit von Kaolinteilchen
Authors: Chmelir Miroslav , Künschner Alois , Barthell Eduard 
Published: April 2003

AbstractDie Sedimentationsgeschwindigkeit von feinen in Wasser suspendierten Kaolinteilchen erhöhte sich um den Faktor 200, wenn eine kleine Menge (1 bis 4 ppm) Polyacrylamid zur Suspension gegeben wurde. Die Sedimentation war abhängig von der Polymerkonzentration, dem Molekulargewicht und dem Carboxylgruppengehalt in hydrolysiertem Polyacrylamid. Die beste Flockungswirkung wurde durch die Polymeren mit dem höchsten Polymerisationsgrad und einem Gehalt von 30 bis 40% Carboxylgruppen im hydrolysierten Polyacrylamid erzielt.
Water soluble acrylamide polymers, 2. Aging and viscous flow of aqueous solutions of polyacrylamide and hydrolyzed polyacrylamide
Authors: Chmelir Miroslav , Künschner Alois , Barthell Eduard 
Published: April 2003

AbstractThe aging of aqueous solutions of polyacrylamide which appears experimentally as a decrease of solution viscosity and which is probably caused by microorganisms may be prevented by the addition of a small amount (0.02 wt.‐%) of an antimicrobial agent such as sodium azide. Aluminium chloride causes a very strong decrease of the viscosity during a prolongated storing time. The addition of aluminium ions to the polymer solution leads to a complexing of amidic groups with aluminium cations and probably also to decrease of the dimensions of individual polymer coils.The viscous flow of aqueous solutions of polyacrylamide and hydrolyzed polyacrylamides was studied as a dependence of the shear gradient D on the shear stress τ and was described by the relation D = k · τn, where k and n denote constants. Both constants depend on the polymer concentration, the degree of polymerization and the content of carboxylic groups in the polymer. The greatest deviations from the Newtonian behaviour were found in the range of molecular weights over 2 · 106 g/mol and practically no deviations were observed for polyacrylamide with molecular weights below 1 · 106 g/mol. The dependence of the viscosity on the shearing time at different shear rates (300, 600 and 1200 s−1) which was observed in solutions of polyacrylamide, hydrolyzed polyacrylamide and poly‐(N,N‐dimethyl)‐acrylamide was explained by an entanglement model.
Macroporous styrene‐divinylbenzene copolymers as carriers for poly(vinylamine)‐cobaltphthalocyanine oxidation catalysts
Authors: Schutten Jan H. , Van Hastenberg Christianus H. , Piet Pieter , German Anton L. 
Published: April 2003

AbstractMacroporous highly crosslinked styrene(St)‐divinylbenzene(DVB) copolymers were prepared by solution and suspension polymerization techniques. The obtained materials allowed the grafting of poly(N‐vinyl‐tert‐butylcarbamate) (PVCa) either by addition of VCa macroradicals to the solid bound double bonds or by termination involving the reaction of VCa macroradicals with radicals present on the carrier. Poly(vinylamine) (PVAm) grafted on St‐DVB carriers was obtained after the hydrolysis of grafted PVCa with HCl and the subsequent removal of the aminebonded HCl by means of NaOH. Heterogeneous bifunctional catalysts were obtained by attachment of cobalt(II) 4,4′,4″,4‴‐tetracarboxyphthalocyanine (CoPc(COOH)4) to the grafted PVAm. The prepared catalysts were applied to the autoxidation of thiols to disulfides, both in predominantly apolar media and in aqueous media. It was demonstrated, that important prerequisites for the applicability of macroporous St‐DVB copolymers as carriers for the PVAm‐CoPc(COOH)4 catalyst include a high surface area, a sufficiently large average pore diameter and accessibility of the pendent double bonds.
Mechanochemically initiated polymerizations II. Influence of some factors on the mechanochemical homopolymerization of acrylonitrile by vibratory milling
Authors: Oprea C. V. , Popa M. 
Published: April 2003

AbstractThe paper is an evidence for the capacity of mechanical energy, released by vibratory milling (VM) to activate homopolymerization reactions. The polymerization of acrylonitrile without any initiators or classical catalysts is presented.The influence of some parameters of the mechanical process (filling ratio, duration, wearing degree of the milling bodies, reaction medium) was studied. Kinetical aspects of mechano‐chemical homopolymerization of acrylonitrile at different conditions are discussed.
Study of the stability of some imide type polymers in alkaline medium
Authors: Neamţu Gabriela , Airinei Anton , Brumǎ Maria 
Published: April 2003

AbstractThe stability of some polyamide‐imides in alkaline medium was compared to the structurally related amide and imide homologs. The following order of stability in alkaline medium was established: aromatic polyamide > polyamide‐imide > polyimide. This order results from the different stabilities of the poly(amic acids) formed as a result of the hydrolysis.The presence of carboxylic substituents in the ortho position to the amide groups of the poly(amic acids) determines the different stability of polymers.
Biconstituent fibres of nylon 6‐poly(ethylene terephthalate)
Authors: Garg V. , Nagendra C. L. , Misra A. , Chaudhary V. , Varma D. S. 
Published: April 2003

AbstractBiconstituent fibres of nylon 6 and Poly(ethylene terephthalate) (PET) were prepared. Nylon 6 and PET polymers were mixed in different proportions viz. 90 : 10, 80 : 20, 70 : 30, 50 : 50 and melt blended in a glass autoclave at a temperature of about 265 ± 5°C in nitrogen atmosphere. The blended chips were melt spun and the resulting fibres were hot drawn at 125°C to 2, 3, 4 and 5 draw ratios.Mechanical properties of the fibres were evaluated. The 70 : 30 blend of nylon 6‐PET gave a fibre with high modulus and tenacity. The results were discussed in terms of morphological and crystalline structure.