bluuebunny/crossref_metadata_2025 huggingface dataset:
Decomposition of hydrogen peroxide catalyzed by perchloric acid. Application of this initiation system in the preparation of HO‐terminated telechelic polymers of butadiene
Authors: Bouchal K. , Žůrková E. , Kálal J. , Sufćák M. , Seyček O.
Published: April 2003

The kinetics of hydrogen peroxide decomposition was followed in the presence of perchloric acid. The reaction was of second order with respect to the initial concentration of hydrogen peroxide and of first order with respect to the concentration of perchloric acid; the determined activation energy was 102.5 kJ · mol−1. The investigated reaction was retarded by oxygen and accelerated by allyl compounds. The mechanism of hydrogen peroxide decomposition in the presence of perchloric acid is discussed on the basis of kinetic parameters. The reaction was utilized in the initiation of radical synthesis of HO‐terminated telechelic polybutadienes and copolymers of butadiene with polar vinyl compounds.
Graft copolymerization of vinyl monomers on modified cottons XV. Initiation by decomposition of aryl diazonium groups
Authors: Hebeish A. , Abdel‐Bary E. M. , Waly A. , Bedeawy M. S.
Published: April 2003

Cellulose bearing aromatic amino groups was prepared by reacting cellulose with 2,4‐dichloro‐6‐(p‐nitroaniline)‐s‐triazine in presence of alkali followed by subsequent reduction of the nitro groups to amino groups. The latter were diazotized and grafting was achieved without homopolymer contamination through decomposition of the cellulose diazonium salt under the effect of metal ions. The dependence of grafting on the nature of the monomers was governed by the pH of the polymerization medium, reaction temperature and concentration of emulsifier. Using a large liquor ratio decreased the graft yield. The cellulose macroradical formed via decomposition of the diazo group was found very effective in inducting methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, isopentyl methacrylate, acrylamide and 2‐methyl‐5‐vinyl pyridine.
Weak base polystyrene anion exchangers II Relation between their structure and structure of sorbates
Authors: Wojaczyńska Maria , Kolarz Bożena
Published: April 2003

The influence of the structure of styrene‐divinylbenzene copolymers, which make up the matrix of weak base anion exchangers with mono‐ and diethanolamine functional groups on their sorption properties in relation to acid dyes with increasing molecule size has been investigated. It has been found that the copolymer gel heterogeneity induced by the presence of an inert diluent has a marked effect on the degree of sorption and its course. The acid dyes with a higher sulfonic group content were found to be sorbed mainly by the formation of aggregates in the ion exchanger, and the homogeneity of their structure facilitates the process.
Metering of peroxidic polymerization initiators at elevated pressure
Authors: Luft Gerhard , Seidl Hans
Published: April 2003

Metering of polymerization initiators, which has to take place at relatively low temperatures to prevent premature decomposition, involves the risk of the initiators crystallizing out at the high pressures involved. For this reason, the solubility of different peroxides, which are highly efficient initiators for radical chain polymerization, was investigated in isododecane and other commonly used solvents. The measurements were carried out at temperatures of −30 to +40°C and pressures up to 3000 bar in ranges of concentration between 50 and 100 wt.‐%. It was found that both tert.‐butyl perpivalate and tert.‐butyl perbenzoate, and to a lesser extent, di‐tert. ‐butyl peroxide, need to be diluted in order to avoid undesirable precipitation of solids. A substantial improvement in the solubility of the peroxides examined could be achieved by replacing the tertiary butyl group with a tertiary amyl group. On the basis of the solubility values determined, recommendations are made on the necessary dilution of the peroxides and the choice of solvent.
Photochemical investigations into cellulosic materials I. Free radical generation in cellulose by photosensitized excitation
Authors: Merlin André , Fouassier Jean‐Pierre
Published: April 2003

UV irradiation of cellulose, both in photosensitized and unphotosensitized experiments results in chain scission and radical generation on the glucosidic cycle, as observed by ESR spectroscopy. It was shown that sensitizers of the benzoin and benzophenone family induce radicals very efficiently on cellulose. The results obtained with several benzoin derivatives and benzophenone are discussed in connection with the ESR spectra, in terms of the primary processes involved during the photolysis of these compounds in cellulose. Features relevant to photografting are derived from these experiments.
Photochemical investigations into cellulosic materials II Photosensitized grafting of MMA onto cotton
Authors: Hérold Robert , Fouassier Jean‐Pierre
Published: April 2003

Grafting of methylmethacrylate onto cotton has been investigated, using organic molecules as photo‐initiators. Several parameters of the reaction have been studied and the results have been compared with those obtained in unphotosensitized experiments. A grafting of about 200% may be achieved by irradiating with commercially available lamps. The results are discussed with special emphasis on the reactivity of the initiators.
Urea‐formaldehyde resins. 3. Formation and reactions of monourea methylol compounds during resin preparation
Authors: Kumlin Kjell , Simonson Rune
Published: April 2003

The content of each individual monourea methylol compound, as well as that of urea and free formaldehyde, respectively, in urea‐formaldehyde (UF) resins is given. The reaction was carried out in concentrated UF solution at elevated temperature. The influence of the pH, the F/U molar ratio, the reaction temperature, and the reaction time was studied.

To obtain a low formation of condensed products, the pH had to be kept around 8.5 during the preparation (F/U = 1.4).
Composition and structure of the cation permselective membranes I. Evaluation of the electrochemical models
Authors: Narębska Anna , Wódzki Romuald , Koter Stanisław
Published: April 2003

The swollen permselective membrane is a multiphase system composed of polyelectrolyte gel, inert polymer acting as a reinforcing agent and of low molecular weight electrolyte filling the pores and nonselective domains.

Endeavour has been undertaken to apply the electrochemical models of membranes for the computations of their phase composition. The computations have been performed for some cation selective membranes equilibrated with sulphuric acid solutions, which are called NAFION, PE‐PSSA, and IONAC. The results prove that only the Guillou model fulfills some of the chosen criteria of adequacy. It has been also stated that the fraction of the nonselective domains found by any of the models exceed the one established from electrolyte sorption data.
Photoabbau von PVC‐Folien II. Photooxidative prozesse
Authors: Braun D. , Kull S.
Published: April 2003

Masse‐PVC und VC/CO‐Copolymerfilme wurden in Luft und reinem Sauerstoff mit einer Quecksilberhochdruckdampflampe bestrahlt. Die HCl‐Abspaltungsgeschwindigkeit, die Verfärbung sowie die Photooxidation werden beschrieben. Anwesender Sauerstoff retardiert die HCl‐Eliminierung und verändert die Geschwindigkeit der Ausbildung von Verfärbungen. Die für die Photooxidation im Vergleich zur Photoeliminierung hohe Aktivierungsenergie von 21 kJ mol−1 läßt die beiden Prozesse temperaturabhängig miteinander konkurrieren.
Zur Analyse von Milchsäure‐Glykolsäure‐Copolyestern
Authors: Aydin Oral , Jacobi Erhard , Schulz Rolf C.
Published: April 2003

Für L‐(–)‐Lactid‐Glykolid‐Copolyester (3) wurden drei voneinander unabhängige Analysenmethoden zur Bestimmung der Copolymeren‐Zusammensetzung ausgearbeitet. Die 1H‐NMR‐Spektroskopie wurde für Copolyester mit Lactid‐Gehalten über 10 Gew.‐% erfolgreich angewandt, nachdem mit Trifluoressigsäure ein geeignetes Lösungsmittel gefunden war. Insbesondere für die praktisch interessanten Materialien mit kleinem Lactid‐Anteil, wie z. B. resorbierbares chirurgisches Nahtmaterial, eignen sich die Messung der optischen Rotation sowie eine chemische Methode, die auf der quantitativen Bestimmung der Milchsäure nach vorhergehender alkalischer Totalhydrolyse beruht.
Thermoelektrische analyse (TEA), eine neue Methode zum gleichzeitigen Studium elektrischer und thermischer Eigenschaften von Polymeren
Authors: Weber Gunter , Vogel Burkhard
Published: April 2003

Es 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

Linear 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

The 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

The 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

Macroporus 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

Es 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

Die 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

Controlled 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

Mit 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

The 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

The 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

Polyurethanes 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

Semi 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

It 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

The 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

Dyeing 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

In 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

In 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

Die 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

Unter 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

Die 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

The 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

Macroporous 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

The 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

The 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

Biconstituent 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.
Grafting onto wool X. Graft copolymerization of vinyl acetate and methyl acrylate in presence of potassium persulphate — ferrous ammonium sulphate (KPS‐FAS) system as redox initiator
Authors: Misra B. N. , Dogra R. , Mehta I. K. , Singha A. S.
Published: April 2003

Graft copolymerization of vinyl acetate (VAC) and methyl acrylate (MA) onto Himachali wool was studied at 40, 45, 50, and 60°C in aqueous medium by using (KPS‐FAS) system as redox initiator. The maximum grafting of both VAC and MA occurred at 60°C. The nature of vinyl monomer was found to influence grafting. The percentage of grafting was determined as functions of (a) concentration of monomer, (b) molar ratio of FAS/KPS, (c) reaction time and (d) temperature. Maximum grafting of both VAC and MA occurred at a molar ratio of FAS:KPS = 0.713 : 1. The rate of grafting (Rp) and the induction period (Ip) of VAC and MA were determined as a function of total initial monomer concentration. MA, an acceptor monomer was found to be several times more reactive than VAC, a donor monomer.
Grafting vinyl monomers onto wool fibers, IX. Graft copolymerization of methyl methacrylate onto wool using peroxydiphosphate‐cysteine redox system
Authors: Nayak Padma L. , Lenka Subasini , Mishra Munmaya K.
Published: April 2003

The graft copolymerization of methyl methacrylate onto wool was studied at 50°C using peroxydiphosphate‐cysteine redox system as initiator. The rate of grafting was determined by varying monomer, initiator, cysteine, acid and temperature. The grafting is considerably influenced by chemical modification prior to grafting. A suitable kinetic path has been pictured and a rate expression has been derived.
Functional monomers and polymers, 85. On the adsorption of bromine onto chitosan
Authors: Shigeno Yasuhiro , Kondo Koichi , Takemoto Kiichi
Published: April 2003

The adsorption of bromine onto powdery chitin, chitosan and cellulose was studied in an aqueous bromine‐potassium bromide solution at 30°C. Chitosan was found to show an excellent ability of adsorbing bromine as well as iodine. The chitosan film also exhibited high ability of adsorbing bromine both in methanol and in aqueous potassium bromide solutions.
Functional monomers and polymers, 74. Physico‐chemical study on the chitosan‐iodine complexes
Authors: Shigeno Yasuhiro , Kondo Koichi , Takemoto Kiichi
Published: April 2003

The adsorption of iodine on chitosan was studied by physico‐chemical methods. The scanning electron micrograph measurements of chitosan‐iodine adducts showed that iodine molecules were adsorbed uniformly on the chitosan film when the film was treated with aqueous iodine‐potassium iodide solution. The thermogravimetric analysis of the adducts revealed that the loss in weight began at about 190°C, and that iodine molecules were thus well‐complexed with chitosan. It was also found that the IR spectra of the chitosan films showed the amide I and amide II bands shifted to lower frequencies due to the iodine adsorption. The X‐ray diffractometry of these adducts was further carried out, and it was found that the iodine adsorbed chitosan showed no crystalline pattern, different from that of the original chitosan which showed crystallinity in some extent. The chitosan recovered after desorbing iodine by immersion in aqueous sodium thiosulfate solution was amorphous.
Preparation of copolymers from styrene and some unsaturated ketones and studies on their photodestruction in a condensed phase
Authors: Nenkov G. , Georgieva T. , Stoyanov A. , Kabaivanov V.
Published: April 2003

A comparative photodestruction study was carried out on solid state copolymers of styrene with methyl vinyl ketone, methyl isopropenyl ketone, phenyl vinyl ketone, benzalacetone and benzalacetophenone. The photolysis of the examined copolymers was found to proceed rapidly higher destruction rates being observed with increasing the ketone concentration. The rate of light‐induced destruction for the first three copolymers was markedly greater than that of the styrene‐benzalacetone and styrene‐benzalacetophenone copolymers. The photodestruction proceeds probably by the Norrish II mechanism.
Heat transfer printing of polyester using alginate films
Authors: El‐Thalouth I. Abd , El‐Kashouti M. A. , Hebeish A.
Published: April 2003

The suitability of coloured alginate films in heat transfer printing of polyester fabric was examined. The colour strength of the prints depended on the dye concentration in the film, temperature and, to some extent, the time of transfer. The prints acquired excellent washing fastness and at least four prints having comparable colour strength could be achieved by using the same film.
Enzyme immobilization on polyglycidylmethacrylate graft‐copolymer of different polysaccharides
Authors: D'Angiuro L. , Cremonesi P. , Cantafi R. , Mazzola G. , Vecchio G.
Published: April 2003

Comparative results obtained in preparing and characterizing samples of enzymes immobilized by reaction with polyglycidylmethacrylate (PGMA) copolymers with different polysaccharide matrices are reported. Sepharose copolymers having between 25 and 50% synthetic polymer were used to find the best immobilization conditions of horseradish peroxidase (HRP) and glucose‐oxidase (GOD) (pH, time, temperature, enzyme cncentration). Activity, enzyme loading and coupling efficiency of immobilized HRP and GOD are greatly dependent on the type of matrix while the polymer content is less important. Coupling efficiencies between 0.8 and 1.5% have been obtained for HRP samples, whereas for GOD samples coupling efficiencies three times greater were obtained. HRP and GOD immobilized samples show Km′ values greater than those of corresponding free enzymes and this indicates diffusion limitation phenomena.

Storage, thermal and operational stability were also studied. In general the storage stability could be considered satisfactory (50% residual activity after 360 days). Sepharose and starch HRP‐copolymers had an improved thermal stability compared with that of free enzyme. Residual activity found in continuous operation tests carried out on HRP‐immobilized samples turned out to be dependent on support. HRP‐PGMA‐Cellulose sample gave the best results (50% residual activity after 16 days). PGMA‐graft‐copolymers have also been used to immobilize other enzymes such as α‐amylase, α‐chymotrypsin and cellulase.
Reaktive Träuger mit Maleinimidgruppen zur Enzymimmobilisierung
Authors: Manecke Georg , Middeke Hermann‐Josef
Published: April 2003

Es wurden hochpolymere Träger mit Maleinimidgruppen dargestellt und deren Bindungsverhalten für Cystein und thiolgruppenhaltige Enzyme in Abhängigkeit von verschiedenen Parametern wie Enzymkonzentration, Temperatur, pH‐Wert, Reaktionszeit und Harnstoffkonzentration untersucht. In Trypsin und α‐Chymotrypsin, die keine SH‐Gruppen aufweisen, wurden Thiolgruppen durch Thiolierung mit N‐Acetyl‐D,L‐homocysteinthiolacton eingeführt. Die am Polymeren gebundene Enzymmenge und die Aktivität der Immobilisate wurden bestimmt.
Biaxiales Recken und Orientierungszustand von Polymeren II. Experimentelle Untersuchungen an Polyethylenterephthalat‐Folien
Authors: Jungnickel Bernd‐ J.
Published: April 2003

Unter Annahme eines pseudoaffinen Deformationsmechanismus wurden sehr allgemeine quantitative Zusammenhänge zwischen Orientierungszustand und Reckgeometrie hergeleitet. Diese Beziehungen werden zur Analyse des Bowing sowie der Abhängigkeit des Orientierungszustandes von der Recktemperatur bei technischen Polyethylenterephthalat‐Folien herangezogen. Rechtfertigend hierfür ist der Nachweis, daß bei aus dem amorphen Zustand gereckten Folien die pseudoaffin transformierten Strukturvektoren von der Kettenrichtung in den kristallinen Bereichen repräsentiert werden. Es zeigt sich, daß bereits geringe Störungen der Reckgeometrie zu einer deutlichen Verlagerung der mittleren Kettenrichtung führen. Die Unterschiede zwischen den berechneten und gemessenen Orientierungsgraden werden dem plastischen Anteil and der Verformung zugeschrieben.
Derivatives of lignin as synthetic tanning agents
Authors: Gemei Mervat S. , Makar Saad M. , Saleh M. Salah El‐Din
Published: April 2003

Alkali lignin was successfully converted to chemical derivatives which could be used as synthetic tannins for leather production. The prepared lignin derivatives were: nitrolignin, aminolignin and chlorolignin. their affinity to chromed hide powder and polyamide powder as model substances for collagen was tested by column chromatography.

Aminolignin showed a higher percentage adsorption on chromed hide powder than nitrolignin and chlorolignin, indicating strong irreversible bonding.

Measurements of the shrinkage temperature (Ts) of the pelts tanned with those compounds showed that the tanning effect of aminolignin on delimed pelts was satisfactory, and almost similar to the tanning effect of vegetable tannins, followed by nitrolignin, whereas chlorolignin showed a slight increase in the Ts values of tanned pelts, i.e. weak tannage properties.
Synthesis and properties of some alkenyl‐ and alkinyl‐2‐cyanoacrylates
Authors: Kotzev Dimiter L. , Novakov Peter C. , Kabaivanov Vladimir S.
Published: April 2003

Some alkenyl‐ and alkinyl‐2‐cyanoacrylate monomers, possessing adhesive properties were synthesized. The ease of esterification of cyanoacetic acid, the first step of the synthesis, with some alcohols was in the following order:
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After condensation of the cyanoacetates with formaldehyde to low molecular weight polymers and depolymerization in vacuum, allyl‐2‐cyanoacrylate, propargyl‐2‐cyanoacrylate, 1‐methyl‐2‐propinyl‐2‐cyanoacrylate and 1‐propyl‐2‐propinyl‐2‐cyanoacrylate were obtained, the last two for the first time. It was found that the strength of the adhesive bonds of these monomers depends primarily on the number of C atoms in the ester group of the molecule, i.e.
magnified image
The introduction of double and triple bonds increases the tensile strength properties. The unsaturated cyanoacrylates also have a better heat‐resistance of their bonds: CH2CHCH2 > CHCCH2 > CHCC(CH3)H > CHCC(C3H7)H > alkyl. This result is explained with the formation of cross‐links in the adhesive layer, confirmed by IR and thermogravimetric data.
Antioxidants and stabilizers, 81. Transformations of N,N′‐diphenyl‐ and N‐phenyl‐N′‐isopropyl‐1,4‐benzoquinonediimines on silicagel
Authors: Taimr L. , Pospíšil J.
Published: April 2003

Transformations of N,N′‐disubstituted 1,4‐benzoquinonediimines have been investigated as a means for the elucidation of processes occurring in hydrocarbon polymers stabilized with amine antidegradants and of transformations accompanying the analyses of extracts of aged rubbers. N‐Phenyl‐N′‐isopropyl‐1,4‐benzoquinonediimine (1b) is quickly hydrolyzed on a silicagel surface, giving rise to N‐phenyl‐1,4‐benzoquinoneimine (3). The hydrolysis of N,N′‐diphenyl‐1,4‐benzoquinonediimine (1a) proceeds more slowly under the same conditions, but the released aniline quickly reacts with the initial (1a), giving rise to N,N′‐diphenyl‐1,4‐phenylenediamine(2a), 2‐(phenylamino)‐N,N′‐diphenyl‐1,4‐benzoquinonediimine (4) and azophenine (5). The Reaction is catalyzed by the weakly acid surface of silicagel. Compound (4) is readily disproportionated thermally to 1,2,4‐tris(phenylamino)‐benzene (8) and 2, 10‐dihydro‐10‐phenyl‐2‐(phenylimino)phenazine (9), even in the absence of a catalyst. A mechanism of the formation of compounds arising in the reaction has been suggested. Diimine (1a) possesses a higher oxidation potential than all the products derived from it, so that it is quickly reduced by these products to (2a). The gradual formation of (2a) may explain the retardation effects of (1a) in the autooxidation of hydrocarbon substrates.
Antioxidantien und Stabilisatoren, 82. Antioxidative Eigenschaften von Amiden der Phosphorsäure
Authors: Rüger C. , Schwetlick K. , Jiráčková L. , Pospíšil J.
Published: April 2003

Aromatische und aliphatische Amide der Brenzcatechylphosphorsäure wurden auf ihre Wirksamkeit als Antioxidantien überprüft. Es wurde der Einfluß dieser Verbindungen auf die AIBN‐initiierte Oxidation von Tetralin bei 60°C sowie auf die Oxidation von isotaktischem Polypropylen bei 180°C untersucht. Eine Aktivität der untersuchten Verbindungen als kettenabbrechende Antioxidantien tritt nur bei Phosphorsäureamiden, die sich von primären Aminen ableiten, auf. Gegenüber Derivaten der phosphorigen Säure ist die antioxidative Aktivität wesentlich erniedrigt. Es wird ein Wirkungsmechanismus von Esteramiden der Phosphor‐ bzw. phosphorigen Säure als radikalkettenabbrechende Antioxidantien diskutiert.
Mechanochemically initiated polymerizations. Characterization of poly(acrylonitrile) mechanochemically synthesized by vibratory grinding
Authors: Oprea Cleopatra Vasiliu , Popa M.
Published: April 2003

Mechanical energy which is released by vibratory grinding is able to initiate polymerization reactions of some vinylic monomers. On this way it was possible to obtain poly(acrylonitrile) without any initiator or classical catalyst. The paper presents the physico‐chemical properties of the products obtained by vibratory grinding of acrylonitrile. For the characterization of the obtained polymers, IR‐, ESR‐, and Mössbauer‐spectra were used, together with X‐ray diffraction. Based on the chemical composition and spectral analysis a reaction mechanism and the polymer structure were proposed.
The decomposition of hydrogen peroxide catalyzed with BF3 etherate; the use of this initiation system in the preparation of HO‐terminated telechelic polymers and copolymers of butadiene
Authors: Bouchal K. , Žůrková E. , Kálal J.
Published: April 2003

Kinetics of the catalyzed decomposition of hydrogen peroxide in the presence of BF3 etherate were investigated, and the basic kinetic parameters used in the discussion of the mechanism of this reaction were determined. The system hydrogen peroxide‐BF3 etherate was used in the initiation of the radical polymerization and copolymerization of butadiene. The parameter φ was determined using an analysis of the kinetics of copolymerization of butadiene with acrylonitrile and the Simha‐Branson equation; the dependence of φ on the composition of the copolymerization mixture was interpreted in terms of Arlman's equation. The cross‐termination reaction occuring in the copolymerization of butadiene with acrylonitrile was characterized by comparing theoretical and experimental functions.
Partial esterification of poly(vinyl alcohol) with acid chlorides
Authors: Arranz F. , Chaves M. Sánchez , Gil F.
Published: April 2003

This work deals with some features of the reaction of organic acid chlorides with poly(vinyl alcohol). The structure of the modified polymers was determined by means of IR, UV and NMR spectroscopy as well as by chemical analysis. Vinyl alcohol‐vinyl butyrate copolymers were obtained by reaction of poly(vinyl alcohol) with n‐butyryl chloride without any catalyst. The reaction appeared to satisfy a second order kinetics for conversions no higher than 50%. The activation energy found was of 9.9 kcal/mol. The use of pyridine as a catalyst involved a noticeable increase of the reaction rate, but this effect was found to be independent of the acid chloride used. When triethylamine was used as a catalyst, β‐keto ester groups were found to be grafted onto the polymer chain. The steric hindrance of these groups were thought to be sufficiently important for the conversion to reach a limit of about 30%. The observed swelling in water of vinyl alcohol‐vinyl butyrate copolymers made it reasonable to conclude that the hydrophilic character of the copolymers decreased progressively when the ester group content increased.
Reactive polymers, XXXIV. Complexes of Ag(I) and Ag(II) with ligands bound to solid support
Authors: Švec F. , Kálalová E. , Tlusťáková M. , Kálal J.
Published: April 2003

The sorption of Ag(I) ions on sorbents containing ethylenediamine (en) and iminodiacetate (ida) groups was investigated. The basic backbone consisted on macroporous glass coatd on its inner surface with poly(glycidylmethacrylate) (glass‐GMA), copolymer glycidylmethacrylate‐ethylenedimethacrylate (GMA‐EDMA), and GMA‐EDMA encapsulated in poly(‐2‐hydroxyethylmethacrylate). The rate of sorption of Cu(II) in sorbents modified with en decreased in the same order. For the sorption of Ag(II), a sorbent was synthesized by a reaction of GMA‐EDMA with 3‐aminopyridine, and the reaction with the ion was carried out in an oxidizing solution. The types of complexes formed in the sorption were determined spectroscopically in all cases.