bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence de la température sur i'écoulement des polymères. Correlation pratique et mathématique de i'énergie d'activation de i'écoulement pour le polyéthylène basse‐densité, polyéthylène haute‐densité, polystyrène et d'autres polyoléfines
Authors: Déri Fawaz , Aldeyab Salem , Majid Balkhi Abdel
Published: April 2003

Nous avons étudié les propriétés rhéologiques des matériaux à l'état fondu au moyen d'un viscosimètre à capillaire.

Nous avons essayé de relier les valeurs des énergies d'activation, à vitesse et tension de cisaillement constantes, avec les valeurs de l'indice d'écoulement.

Les valeurs de l'indice d'écoulement obtenues selon l'approche mathématique ne coincident pas avec les valeurs obtenues expérimentalement. L'énergie d'activation de LDPE est supérieure à celle du HDPE en raison du volume libre de LDPE qui est plus grand.
Changes in structure of PA fibres during mass colouration
Authors: Wlochowicz A. , Broda J. , Ślusarczyk C.
Published: April 2003

The effect of organic pigments on the supermolecular structure of mass coloured PA fibres has been investigated by means of small‐angle and wide‐angle X‐ray scattering methods. It has been found that the dye molecules introduced in polymer melt before the fibre is formed take part in the formation of the supermolecular structure of the fibres. The presence of these molecules causes changes of the weight fractions of the polymorphic forms of the polyamide, the increase of the crystallinity index of the fibres and the increase of the thickness of the transition layers between crystalline and amorphous regions. Changes which have been observed are dependent both on the content of pigments and on their chemical nature.
Salicylic acid‐biuret‐trioxane terpolymer resins and their ion‐exchange properties
Authors: Pal T. K. , Kharat R. B.
Published: April 2003

Terpolymer resins (SBT) were synthesized by the condensation of salicylic acid and biuret with trioxane in the presence of acid catalyst and using varied molar ratios of reacting monomers. Terpolymer resin compositions have been determined on the basis of their elemental analysis and the number average molecular weights of these resins were determined by conductometric titration in non‐aqueous medium. The viscosity measurements carried out in DMF indicate normal behaviour. IR spectra were studied to elucidate the structure. TGA data were analysed to estimate the characteristic thermal parameters. The terpolymer resins have been further characterized by reflectance spectra in solid state, absorption spectra in non‐aqueous medium, X‐ray diffraction and electrical conductivity. Chelation ion‐exchange properties have also been studied employing the batch equilibration method.
Ammoniakdiffusion in Polymerfilmen
Authors: Müller F. W. , Schiller K. , Jänchen U. , Marx J.
Published: April 2003

Mit Hilfe einer neuartigen Untersuchungsmethode wurden die Diffusionskoeffizienten von Ammoniak (NH3) in 22 transparenten filmbildenden Polymeren bei Raumtemperatur bestimmt. Die Methode beruht auf der UV‐VIS‐spektroskopisch verfolgbaren reversiblen Reaktion von Ammoniak mit 4‐Nitrophenol zu einem 4‐Nitrophenolat‐Ammoniak‐Meisenheimer‐Komplex.

Die Farbbildungsreaktion im Polymerfilm wurde untersucht und anhand einer einfachen Näherung der Diffusionsgleichung ausgewertet. Die erhaltenen Diffusionskoeffizienten stimmen sehr gut mit den wenigen verfügbaren Literaturwerten überein.

Die Abhängigkeit der NH3‐Diffusionskoeffizienten von der Polymerstruktur ist weitgehend der für permanente Gase bekannten analog.

Die beschriebene Methode erlaubt problemlos, Diffusionskoeffizienten zu messen, die sich bis zu drei Größenordnungen unterscheiden (Ethylcellulose: 1,07 · 10‐7 cm2 · s‐1; Polyvinylalkohol: 0,9 · 10−10 cm2 · s−1).
The mechanism of orientation in cold‐drawn polyoxymethylene as revealed by crystallographic pole figures
Authors: Schweizer Thomas , Vancso Gyula
Published: April 2003

The orientation mechanism of cold‐drawn, partially crystalline polyoxymethylene (ULTRAFORM) samples was studied by performing wide angle X‐ray scattering (WAXS) measurements. The anisotropic samples were prepared in uniaxial tensile tests around 130°C, in a temperature range between the glass transition and the melting point. The process of the plastic deformation is discussed for different degrees of anisotropy. The orientation distribution of the crystalline lamellae was qualitatively characterized by performing pole figure intensity calculations from the measured WAXS intensities. The degree of orientation was quantitatively described by calculating the orientation factors for the [100] normal vector of the unit cell. The texture of the necked samples with high orientation degrees was a mixture of axial and uniplanar‐axial textures. An explanation for the formation of this kind of orientation is proposed assuming an influence of the sample geometry on the orientation process.
The interactions between wood components and formaldehyde‐based resins. I. Monofunctional resin model compounds
Authors: Mora F. , Pla F. , Gandini A.
Published: April 2003

Results are presented on the chemical interactions occurring when some monofunctional model compounds simulating the structure and reactivity of thermosetting phenol‐ and urea‐formaldehyde resins are mixed with wood components (hemicelluloses, cellulose, and lignins). Whereas hemicelluloses clearly show a propensity to give condensation products with these model compounds, lignins can react less readily in some instances depending on the delignification procedure used to isolate them and on the type of model compound. Cellulose did not react under the conditions chosen, mostly because of its crystalline character.
Bigraft copolymer EVA‐g‐AA‐g‐HEMA for biomaterial usage
Authors: Hsiue Ging‐ho , Chu Hsiao‐lung
Published: April 2003

The preparation of a bigraft copolymer of EVA‐g‐AA‐g‐HEMA which is a good biocompatible material from a peracid type polymeric initiator, EVA‐g‐AA peracid, is described. The peracid type membrane has high reactivity and HEMA can be easily grafted onto the film. The biocompatibility test showed that the blood clotting time of the HEMA grafted membrane could be as high as 60 min. The wettability of a grafted membrane decreased as the degree of grafting increased. The grafted membranes have high oxygen and water permeabilities as well as high selectivity for solutes.
Conventional crosslinking studies on low density polyethylene monofilaments
Authors: Mukherjee A. K. , Tyagi P. K. , Gupta B. D.
Published: April 2003

Conventional crosslinking of low density polyethylene (LDPE) was carried out using dicumyl peroxide (DCP) as crosslinking agent. DCP in various concentrations was mixed with LDPE chips in an extruder at 135 – 145°C. Monofilaments were drawn on a laboratory drawing machine at 110°C. It was found that tensile properties, percent shrinkage and density were improved with the increase in the concentration of DCP and in the heating period, whereas, however, the percent swelling decreased.
Kationisierung von Zellstoff unter homogenen reaktionsbedingungen
Authors: Ott Gerhard , Schempp Walter , Krause Thomas
Published: April 2003

Es wurde der Versuch unternommen, durch Umsetzung von Zellstoffen mit Glycidyltrimethylammoniumchlorid im Lösungsmittelsystem Dimethylacetamid/Lithiumchlorid kationische Cellulosederivate mit möglichst hohen Substitutionsgraden zu erhalten. Hierzu wurden Temperaturabhängigkeit, Reaktionsdauer und Molverhältnis der Reaktanden untersucht. Als optimal erwies sich eine Reaktionsdauer von 8 h bei einer Reaktionstemperatur von 70°C. Der Cellulosegehalt in Lösung und das Molverhältnis der Reaktanden müssen dem verwendeten Zellstoff angepaßt werden.
Synthese und Charakterisierung von Epoxidharzen aus Bisphenol A, Cyanursäuure und Epichlorhydrin
Authors: Braun Dietrich , Vargha Viktoria
Published: April 2003

Aus Bisphenol A, Cyanursäure und deren Mischungen wurden mit Epichlorhydrin Epoxidharze hergestellt. Die entstandenen Produkte wurden durch Gelpermeationschromatographie, FT‐IR‐, 1H‐NMR‐, 13C‐NMR‐Spektroskopie und DSC‐Analyse charakterisiert. Bei den Synthesen entstehen außer den Glycidylderivaten von Bisphenol A und Cyanursäure Spaltprodukte des Isocyanuratringes bzw. deren Glycidylderivate. Die erzeugten Mischharze lassen sich ohne Härtungsmittel in der Wärme vernetzen.
Einfluß der molekularstruktur auf die dauerfestigkeit teilkristalliner kunststoffe
Authors: Goldman A. J. , Kestelman V. N.
Published: April 2003

Der Zusammenhang zwischen der Molekularstruktur eines linearen teilkristallinen Polymeren (HDPE) und seiner Dauerfestigkeit wurde untersucht. Durch die Untersuchung einer größeren Zahl von HDPE‐Proben mit unterschiedlichem Molekulargewicht konnte ein Zusammenhang zwischen der Lebensdauer und dem Viskositätsmittel des Molekulargewichts gefunden werden, der eine quantitative Voraussage der Lebensdauer ermöglicht.
Polymer composites with radical salts of 1‐methyl‐3‐alkylimidazolium‐7,7,8,8‐tetracyano‐p‐quinodimethane and their electric conductivity
Authors: Šorm Miloslav , Nešpůrek Stanislav , Koropecký Igor , Kubánek Vladimír
Published: April 2003

The polymer composites were prepared by reticulate doping of polystyrene and poly(γ‐methyl‐L‐glutamate)(PMGA) with 1‐methyl‐3‐alkylimidazolium‐7,7,8,8‐tetracyano‐p‐quinodimethane simple salts I and complex salts II. The electric conductivity strongly depends on the chemical structure of the donor, on the stoichiometry and concentration of the radical salts, on the type of the polymer, and on the preparation conditions of the films. A high conductivity, even higher than that of pure radical salts measured in pressed pellets, was obtained in the PMGA doped films, and is most probably due to the α‐helical conformation. This high order conformation of molecules forces microcrystals of charge transfer salts to grow in long hair‐like shapes distributed regularly in the bulk of the polymer film.
Eine neue methode zur herstellung von hydroxyterminierten polydienen
Authors: Trathnigg B. , Krause D. , Dworczak R. , Maier B. , Junek H. , Schmidt A.
Published: April 2003

Es wird gezeigt, daß hydroxyterminierte Polydiene mit guter Mikrostruktur und Funktionalität sowie enger Molekulargewichtsverteilung unter Verwendung von Azobis‐isobuttersäure‐di‐hydroxyethylamid hergestellt werden können. Die Aktivierungsenergie des Initiatorzerfalls wurde durch volumetrische Messung des bei dieser Reaktion freiwerdenden Strickstoffs bestimmt.
Durability of radiation‐sterilized polymers, XIII. The effects of nucleating agent on the oxidative degradation of poly(propylene‐co‐ethylene)
Authors: Kadir Zahrah Abdul , Yoshii Fumio , Makuuchi Keizo , Ishigaki Isao
Published: April 2003

The radiation stability of the random and block poly(propylene‐co‐ethylene) (CP, copolymer with 6% ethylene units) with and without nucleating agent (NA) was compared in relation to radiation sterilization of medical supplies. In both cases, it was found that the radiation stability of CP in the presence of NA was lower than that of CP without NA.

Addition of NA to CP did not improve the transparency but the crystallization occurred at higher temperature. Thus, adding NA to CP has the advantage of shorter moulding time in the production of medical supplies.

The radiation instability of the CP with NA was due to a different crystal structure, because the spherulite shape differs from that of CP without NA. Furthermore, by the chemiluminescence analysis, a higher oxidative degradation was observed in the sample with NA.
Impact behaviour and fractographic analysis of rubber‐modified polybutyleneterephthalate obtained by reactive blending concurrently with polymerization process
Authors: Di Liello V. , Laurienzo P. , Malinconico M. , Martuscelli E. , Ragosta G. , Volpe M. G.
Published: April 2003

Rubber modification of polybutyleneterephthalate was accomplished by the addition of suitable functionalized ethylene‐propylene copolymers (EPR) concurrently with the high temperature polycondensation of 1,4‐butanediol and dimethylterephthalate.

The impact properties of blends obtained with plain EPR, with ester or hydroxyl groups modified EPR were analyzed by Charpy tests performed at different temperatures with a Ceast fracture pendulum. The morphological features of fracture surfaces have also been investigated. An attempt has been made to correlate the morphology of the surfaces with the fracture analysis results.
Detailed reaction engineering as a basis of modern slurry technology for PE‐HD‐production
Authors: Böhm L. L. , Goebel P. , Schöneborn P.‐R.
Published: April 2003

Saving product quality and quality consistency in polymer production needs a detailed knowledge of the polymerization process. A process model for the slurry polymerization of ethylene with high mileage Ziegler‐catalyst/cocatalyst systems has been developed. This model teaches which set of process parameters must be kept constant together with their acceptable deviations to keep product data within the required frame. The consequences for a technical production plant are also discussed.
Note on notch and unnotch toughness of PP‐CaCO3 composites: Influence of filler particle size and dispersion degree
Authors: Švehlová Vítězslava , Polouček Eduard
Published: April 2003

The influence of the filler particle size and dispersion degree on the Charpy notch toughness (U notch) and tensile impact strength (without notch) in the polypropylene‐microground calcium carbonate system was investigated. It was found that while the tensile impact strength was controlled by the content of particles and/or agglomerates coarser than about 10 µm (the strength decreased sharply with their increasing content), the Charpy notch toughness was not decreased even by large agglomerates (up to 100 µm), but dropped heavily with the increasing upper particle size of the filler measured before kneading into polymer. A model system polyethylene‐glass beads revealed even an increase of the notch toughness with the increasing upper diameter of the glass beads (the upper diameter being in the 50–400 µm range).
Polymerization of vinyl acetate in nonionic surfactant microemulsions
Authors: Donescu Dan , Anghel Dan Florin , Balcan Marieta
Published: April 2003

The rate of polymerization of vinyl acetate in microemulsions containing n‐propanol and ethoxylated nonylphenol with 30 moles of ethylene oxide (NP30) depends on the initial composition of the reaction mixture. The reaction is of first order with respect to the initiator (i. e. ammonium persulfate). The induction period increases and the polymer yield decreases by increasing the surfactant concentration. The maximum reaction rate is not affected by the surfactant concentration, but it decreases with the cosurfactant concentration. The rate of initiator decomposition increases with cosurfactant concentration and is lower in the presence of surfactant. The reaction order in case of n‐propanol is of 0.2 in presence of surfactant and of 0.3 in its absence.
Anhäufung von bruchstellen in polydispersen polymeren unter dauerbelastung
Authors: Goldman A. J. , Kestelman V. N.
Published: April 2003

Es wird über die Untersuchungsergebnisse von Lebensdauer und Molmassenänderung an polydispersen Proben von HDPE und HDPE in einem breiten M̄v‐Bereich im Zugversuch in einem oberflächenaktiven Medium berichtet.

Die Arbeit enthält auch die Darstellung der quantitativen Änderung der Molmasse von Hochdruck‐ und Niederdruck‐Polyethylen unter Dauerbeanspruchung und die Analyse der Lebensdauer in Abhängigkeit von den unterschiedlichen Molmassen (MM) (M̄w, M̄n, M̄v); die Unterschiede in Abhängigkeit von der Lebensdauer von M̄v für Proben und polydisperse Muster sowie die Vorstellungen über den dualen Einfluß der Polydispersität auf die Lebensdauer mit einer Interpretation der auftretenden Erscheinungen werden beschrieben.
Temperature dependence of proton spin‐lattice and spin‐spin relaxation times in isotactic polypropylene. Effect of atactic fraction
Authors: Tanaka Hiroshi , Kohrogi Fumie , Suzuki Kazuhiko
Published: April 2003

The temperature of the T1 minimum for the segmental motion in polypropylene containing a lot of atactic fraction is lower than that in isotactic polypropylene. A short T1, T1s, appears for both materials. As the temperature is raised, there is a large increase in T2a (T2 of the mobile amorphous regions), and a mild increase in T2m (T2 of the intermediate regions), while there is no substantial change in T2c (T2 of the rigid crystalline regions). T2a in polypropylene containing a lot of atactic fraction is longer than that in isotactic polypropylene.

The mass fraction of crystalline regions, Fc, decreases and that of the amorphous regions, Fa, increases as the temperature is raised. There is a linear increase in the relaxation rate, 1/(T1min), as the amorphous fraction is increased, except for the sample extracted with boiling n‐heptane. With increase of the peak temperature of tanδ, T2a decreases nearly linearly, while the temperature of the T1 minimum increases.
Copolymerization of methyl methacrylate with maleic anhydride initiated by p‐toluenethiol
Authors: Kuramoto Noriyuki , Shibamura Tomoe , Iwaki Takeshi , Nagai Katsutoshi
Published: April 2003

p‐Toluenethiol (PT) initiates the copolymerization of methyl methacrylate (MMA) with maleic anhydride (MAH) under various conditions. The kinetics of copolymerization of MMA with MAH initiated by PT was investigated in dioxane in the temperature range of 40–60°C, and the rates (Rp) of copolymerization and activation energy were determined. Rp was found to depend on [PT]0.4, ([MMA] + [MAH])2.0. The overall energy of activation was 45.2 kJ/molin the temperature range of 40–60°C. PT was found to be an effective initiating as well as transfer agent. PT induces chain transfer in the copolymerization of MMA with MAH to obtain marked reduction in molecular weight.
Partikelgrößenanalyse von dispersen farbstoffsystemen I. Grundlagen zur partikelgrößenanalyse mittels photonen‐korrelations‐spektroskopie
Authors: Brunger Harald , Schollmeyer Eckhard
Published: April 2003

Eine zur Beschreibung des Färbevorganges von Polyestermaterialien mit Dispersionsfarbstoffen wesentliche Größe stellt die Partikelgrößenverteilung im Farbebad dar. Partikelgrößen unterhalb eines Mikrometers lassen sich in situ nur mit wenigen Meßtechniken bestimmen. Dazu zählt u. a. die Photonen‐Korrelations‐Spektroskopie, die auf Streuung von Laserlicht an kleinen, in einer Flüssigkeit suspendierten Teilchen basiert. Die mathematischen und physikalischen Grundlagen dieser Meßtechnik werden in diesem Artikel erläutert.
Studies on rheological and mechanical properties of isotactic polypropylene‐olefine/styrene block copolymer blends
Authors: Żuchowska Danuta , Steller Ryszard
Published: April 2003

Experimental studies of the blends consisting of isotactic polypropylene and olefine/styrene block copolymers have been carried out. Measurements of viscoelastic and mechanical properties as well as electron microscope observations have shown that the above system has a biphasic structure within the whole composition range. Olefine/styrene block copolymer is a good agent for polypropylene toughening, as the impact strength is increased by several hundred percent especially at low temperatures.
SAXS and WAXS investigations of the crystallinity in polymers
Authors: Rabiej Stanislaw , Wlochowicz Andrzej
Published: April 2003

The crystallinity of polyethylene, polyethyleneterephthalate, and polypropylene was measured with the aid of wide angle (WAXS) and small angle (SAXS) X‐ray scattering methods. The values of crystallinity evaluated using the latter method are distinctly larger than those ones given by the WAXS method. The differences are supposed to be associated with the transition layer existing between the amorphous and crystalline regions. It was concluded that small angle X‐ray scattering cannot be employed as an independent routine method of crystallinity determination.
The thermal decomposition of 2,2′‐azobis‐(2‐methyl‐5‐hydroxy‐valeronitril) and its phenyl isocyanate derivative
Authors: Yuruk H. , Jamil S. , Baysal B. M.
Published: April 2003

The thermal decomposition kinetics of 2,2′‐azo‐bis‐(2‐methyl‐5‐hydroxy‐valeronitrile) was studied in siobutyl methyl ketone, 1,4‐dioxane and cyclohexanone at 61, 71, and 81°C by applying ultraviolet absorption technique. The thermal decomposition of the phenyl isocyanate capped product of this azo‐compound was also studied in isobutyl methyl ketone at the same three temperatures. The overall rate expressions for decomposition of these azo‐initiators in various solvents are reported.
The influence of electron irradiation on the mechanical properties of polypropylene/EPDM rubber blends
Authors: Harnischfeger Peter , Kinzel Peter , Jungnickel Bernd‐Joachim
Published: April 2003

Blends of isotactic polypropylene and EPDM rubber have been treated by electron irradiation in the composition range of rubber modification and in the thermoplastic rubber composition range as well. Mutual crosslinking of the components through the interface could be detected. This intercrosslinking caused a remarkable improvement of the mechanical properties particularly of the thermoplastic rubber.
Fast separation of stabilizers from polyolefins by microwave heating
Authors: Freitag Wolfgang , John Oswaldo
Published: April 2003

The application of microwave heating for the separation of stabilizers from polypropylene and polyethylene was studied. Additives examined were the antioxidants IRGANOX 1010 and IGRAFOS 168 and the light stabilizer CHIMASSORB 81. The polymer samples were kept in sealed vessels and irradiated in a laboratory microwave oven. Fairly quantitative (>90% of the expected content) extraction of the stabilizers from powered polymer was achieved within 3 to 6 minutes using 1, 1, 1 ‐trichloroethane or the 1:1 mixture of acetone and n‐heptane as the extracting solvent.
Eigenverstärkung von thermoplasten im schmelze‐deformationsprozeß
Authors: Ehrenstein Gottfried W.
Published: April 2003

Durch gezielte Beeinflussung der Verarbeitungsprozesse können besonders bei PE, aber auch bei PP erhebliche Selbstverstärkungseffekte erreicht werden. Die Steifigkeit, die Festigkeit und der Verschleißwiderstand werden bis zum 5‐fachen (Spritzguß), sogar teilweise bis zum 20‐fachen (Extrusion) gegenüber normal verarbeitetem Material angehoben. Die Verstärkungswirkung wird durch Shish‐Kebab‐Strukturen erreicht. Sie ist mehrachsig, was für Bauteile grundsätzlich wichtig ist. Erreicht wird dieses durch Begünstigung einer strömungs‐ und druckinduzierten Kristallisation. Die Verfestigung des Materials erfolgt nicht wie üblich durch Abkuhlen sondern ebenfalls druckinduziert. Das Verfahren ist auf konventionellen Verarbeitungsmaschinen realisierbar. Die Strukturen sind sehr stabil.
Mechanisms of photooxidation of polyolefins
Authors: Gugumus F.
Published: April 2003

The mechanisms of photooxidation usually envisaged, are perfected by taking into account photoreactions of peroxy radicals. They involve interaction of a peroxy radical with the polymer to yield a hydroperoxy radical and a pair of macroradicals. After peroxidation, this pair will usually undergo bimolecular termination. The influence of such a reaction on photooxidation kinetics is particularly important for polyethylene. Then, chain termination occurs mainly by interaction of two hydroperoxy radicals or of a hydroperoxy radical with a macroperoxy radical. The reaction does not only affect kinetics of photooxidation but also the nature of the photooxidation products. The latter is more important for polypropylene than for polyethylene.
Investigation of the thermal ageing of polyethylene and polystyrene with the purpose of predicting their shelf‐life
Authors: Trifonova Maria , Evtimova Sonya , Peeva Lili
Published: April 2003

The aim of the present work is to predict the warehouse storage life of polyethylene low‐density, polyethylene high‐density and polystyrene impact‐resistent, using the method of temperature‐time superposition. The properties, most representative for thermal ageing, are the relative elongation at break for polyethylene and the impact resistance for polystyrene. The validity of the predicted shelf‐life is verified by estimating the change of these properties under real conditions of warehouse storage.
Competition between degradation and orientation in semicrystalline polymers
Authors: Raab Miroslav , Mantia Francesco La , Pospíšil Jan
Published: April 2003

This lecture summarizes some recent results and ideas about interrelations between degradation and mechanical behaviour of polyolefins. Aspects of the heterogeneous nature of oxidative degradation in the solid state, the feedback mechanism in degradation, effects of morphology, particularly orientation, on the degradation process, and the influence of degradation on plasticity and on the ultimate mechanical behaviour are discussed.
Thermal and UV degradation of impact‐resistant polystyrene (II)
Authors: Mlinac‐Mišak M. , Jelenčić J. , Bravar M. , Dejanović R.
Published: April 2003

A commercial type of impact‐resistant polystyrene was investigated. Two types of antioxidants, Irganox 245 and Irganox PS‐800 were added to polystyrene in ammounts of 0,05 to 0.20%. Films, dumbbells and straight test pieces were subjected to thermal and u.v. ageing. Films of 250 μ thickness were thermally treated at 100°C and separately u.v. irradiated at 360 nm for 24, 72, 120 and 168 hours. Dumbbells and straight test pieces were only thermally aged at 100°C for 7, 14, 21, 28 and 35 days. Mechanical properties were determined. The spectra of samples were recorded using Perkin‐Elmer, model 1750 FTIR and Perkin‐Elmer data station 7700. Colour changes of all dumbbells were measured using Elrepho apparatus in u.v.‐visible region. (Changes of the content of carbonyl and hydroxyl groups, as well as of polybutadiene (PB) unsaturation in films were recorded on i.r. spektrophotometer Perkin‐Elmer 257 between 4000 and 625 cm−1 and were published in the first part of this study1).
Structural and mechanical changes of polyacrylate systems in correlation with their composition in degradative conditions
Authors: Cerovečki Z̈eljko , Kovačević Vera , Bešić Zdravka , Stanojević Duško
Published: April 2003

Thermal and photodegradation of copolymer system based on styrene, butyl acrylate, acrylic acid and N‐methylolacrylamide (S/BA/AA/MAA) shows mechanical, but no structural changes in examined temperature range and after 320 h of UV irradiation (simultaneously with 256 and 366 nm lamps). Content of acrylic acid is a very important factor for the mechanical stability of these systems which can be very successfully used as the coatings in the practice. Found correlations indicate mechanism and factors having influence on the excellent stability of copolymer films.
Properties of adhesive polymer compositions in ageing conditions
Authors: Kovačević Vera , Šmit Ivan , Kljajič‐Malinović Ljiljana , Sućeska Muhamed , Bravar Mladen
Published: April 2003

In our work the degradative changes in properties of polyurethane adhesives based on aliphatic isocyanates were defined and compared with similar changes occurring when using aromatic isocyanates. The readily observed PUR adhesive discolouration in situations of its contact with leather does imply the necessity for the establishing the real proportions of the polyurethane constituents responsible for this ever‐present problem. The structure‐property relationship of hydroxylterminated polyester‐based segmented aliphatic polyurethanes, as a component in adhesive composition were studied using wide angle X‐ray diffraction spectroscopy (WAXD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) as well as attenuated total reflectance infrared spectroscopy (ATR‐IR) and nuclear magnetic resonance spectroscopy (NMR). The results show that crystalline phase in segmented PUR component influence on morphological and structural properties in degradative conditions.
Kinetic characteristics of the light ageing of rubbers based on polydieneurethanes and polyetherurethanes
Authors: Ivanov V. B. , Kavun S. M. , Tikhonova T. M.
Published: April 2003

The influence of light wavelength and intensity, as well as the temperature, on photooxidation has been studied for rubbers based on polydieneurethane (PDU) or polyetherurethane (PEU). Photooxidation is shown to proceed by the chain free‐radical mechanism with bimolecular (for PDU) or linear (for PEU) kinetic chain termination. The PDU oxidation kinetic parameter is equal to 0.02 [mole/(kg·s)]1/2 and does not depend on temperature. In PEU photooxidation the kinetic chain length is constant in a wide range of light intensities and is equal to 7, while the activation energy is ca 18 kJ/mole. In distinction to PEU, PDU is sensitive not only to UV but also to visible light, with this sensitivity being preserved up to high oxidation levels. The dependences of photooxidation quantum yieldes on wavelength and irradiation time have been determined.
The investigation of structural and morphological changes after the chlorination of rubber surfaces
Authors: Hace Drago , Kovačević Vera , Manojlović Darko , Šmit Ivan
Published: April 2003

The samples of vulcanized rubber compounds with natural rubber (NR) and styrene‐butadiene rubber (SBR) were prepared. The surface chlorination of samples was performed by immersion of strips in aqueous solution of sodium hypochlorite and in hydrochloric acid in dependence of time and in temperature range from 20 °C to 80°C. The changes of chemical structures, thermal stability and morphological properties of chlorinated vulcanizates were recorded by IR‐FMIR spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), wide angle X‐ray diffraction (WAXD) and scanning electron microscopy (SEM). Extremely heterogeneous complex mechanisms of chlorination and parallel degradation processes in dependence on time and temperature above all were indicated and compared to NR and SBR vulcanizates. At higher temperatures the structural changes in elastomeric matrix in connection with selective separation and surface migration of multicomponent filler due to agressive media were observed.
The effect of degradation degree of the dispersed phase on the ozone aging of rubbers filled with crushed rubber powder
Authors: Bořuta Jaroslav , Běhal Miroslav
Published: April 2003

The effect of crushed rubber powder as a filler of rubber compounds on the ozone aging of vulcanizates has been investigated. It has been shown that the ozone resistance depends significantly both on the concentration and the degradation degree of the dispersed phase. Results of laboratory and atmospheric aging tests are summarized.
Influence of small amount dispersive additives on the weather ability of PVC‐films
Authors: Genova Penka , Gancheva Tamara , Marinova Atanasija
Published: April 2003

Three types of transparent PVC‐films before and after exposition in the weather conditions are studied. The first film (the control) is plasticized and stabilized; the second is similar to the first but 1 part of cuprous oxide (CuzO) is incorporated in it, while in the third 1 part of aluminium (A1) powder is added. It is found that the light transparency decreases by 2‐7% upon adding Cu2O and by 17‐36% upon adding Al‐powder. UV‐visible measurements, colourimetric measurements and microscopic investigations are used for examining PVC‐samples properties during weathering. The surface layer chemical changes are studied by means of MIR‐IR‐spectroscopy. The total colour variation (ΔE*ab) in the case of 12 months aged PVC‐film, containing Cu2O, shows 11 relative units in comparison with 37 relative units for the other two materials. A retarding action of Cu2O and an accelerated effect of Al‐powder on the weather degradation of clear soft PVC‐films are established. The influence of the chemical properties and different size distribution of the dispersive additives on photooxidative behaviour of PVC‐compositions are discussed.
Antioxidative efficiency of N‐(arylamine) imides in thermal oxidation of polypropylene
Authors: Matisová‐Rychlá L. , Rychlý J. , Csomorová K. , Velikov A. A. , Kluge R. , Schulz M.
Published: April 2003

Electron‐donating substituents of N‐(arylamine) phthalimides and succinimides promote antioxidative efficiency of these compounds in thermooxidation of polypropylene (190°C, oxygen), while electron‐withdrawing substituents contribute to a reduced volatilization of the polymer. 2,6‐Ditert.butyl‐4‐methylphenol (ionol) raises the antioxidative efficiency of 4‐methoxy and 4‐methyl substituted derivatives displaying a distinct synergism.
Stabilization of linear polyethylene crosslinked by irradiation
Authors: Kiss Peter , Nyitrai Zsuzsanna , Wein Tibor , Bődy Mária , Sipos Csaba
Published: April 2003

Our experiments have shown that after a complex degradative effect, such as processing, irradiation and ageing, the effects of antioxidants and their mixtures are very different.

The results of our investigation support the opinion, expressed by many researchers of stabilization, that there does not exist any universally practicable antioxidative system. The optimal effect has to be determined, for each system, in the knowledge of the quality and quantity of the given oxidative load.

For polyethylene crosslinked by irradiation a satisfactory stability can be attained with the aid of the usual stabilizers; however, they must be used in relatively larger quantities owing to the additional degradative action of the irradiation. There are noticeable differences between the stabilizers not only in their stabilizing action, but also in influencing the degree of discoloration and in the dose number required to produce the same degree of crosslinking.
Studies in ageing of flame retardant high impact polystyrene
Authors: Rosík Ladislav , Virt Jaromír , Masařík Ivo , Horák Zdeněk
Published: April 2003

High impact polystyrene modified with various flame retardants (decabromodiphenyl ether, hexabromocyclododecane, antimony trioxide) and other additives has been prepared. The ageing behaviour and the permanence of the flame retardance were tested. The ageing processes did not appreciably affected the flammability characteristics of the flame retardant high impact polystyrenes although other important material properties (impact strength, gloss, colour) were already considerably deteriorated.
Stabilization of polyacetals
Authors: Stohler Felix R. , Berger Kurt
Published: April 2003

A brief introduction describes the main differences between homo, and copolymer polyacetals and their main degradation mechanisms. A short overview describes the importance of stabilization and the necessity of using antioxidants and costabilizers during manufacturing, processing and end use of polyoxymethylene(polyacetals). Various stabilizer systems are presented and studies on the interaction of antioxidants with costabilizers added. The criteria for testing the performance of these additives are discussed and demonstrated by many examples.

In a second part the increasing importance of light stabilized polyacetal is mentioned and investigations on the performance of light stabilizer systems are highlighted.
Properties and role of benzoquinone imines in polymer stabilization
Authors: Pospíšil Jan
Published: April 2003

Quinone imines are formed from aromatic amine antidegradants as a consequence of chemical transformations of the latter during the stabilization of hydrocarbon polymers. Quinone imines are deep coloured compounds and contribute to the antidegradant activity of the parent amines. The main interest is devoted to benzoquinone diimines (BQDI), generated from N,N '‐disubstituted 1,4‐phenylenediamines (PD). BQDI are antioxidants in unsaturated hydrocarbons, undergo hydrolytic deamination, addition and cyclization reactions, react with 2,6‐dialkylphenols, thiols and C‐centered radicals. PD are regenerated from BQDI in redox reactions. The active role of BQDI in antifatigue processes in rubbers has been explained using product analysis. BQDI account for staining and discoloring properties of PD but are not harmful to the polymer stability.
New oligomers with isatin. Condensation reactions of thiophene and 2,2′‐bithiophene with isatin
Authors: And Francisco Martinez , Naarmann Herbert
Published: April 2003

A systematic study of the well‐known indophenin reaction between isatin and thiophene was extended to embrace bithiophene. The products of the reactions were isolated and characterized by FT‐IR, UV, 1H‐NMR, 13C‐NMR, and GPC. The values of the thus determined molar masses and molar mass distributions differed from the data given in the literature. The reaction conditions – solvent, temperature, and concentration – are of crucial importance for the course of the reaction and the products obtained.

New structures suggested for the oligomeric reaction products agree with all the analytical data. The reactions between isatin and thiophene (bithiophene) are explained schematically.
Partikelgrößenanalyse von dispersen farbstoffsystemen, II. Photonen‐korrelations‐spektroskopie an latexsuspensionen und ‚modellblindfärbungen’︁ von polyethylenterephthalat‐fasern
Authors: Brünger Harald , Schollmeyer Eckhard
Published: April 2003

Als Vorstufe zur Teilchengrößenanalyse von Farbstoffbädern mittels Photonen‐Korrelations‐Spektroskopie werden Latexsuspensionen untersucht. Eine Simulation einer Färbung von Polyestermaterial mit Dispersionsfarbstoffen wird durch eine ‘Modellblindfärbung’ unter Benutzung von Latexsuspensionen bei unterschiedlichen Farbbadtemperaturen nachgestellt. Die sich innerhalb des ‘Färbebades’ ergebenden Partikelgrößenverteilungen werden mit Hilfe der Photonen‐Korrelations‐Spektroskopie analysiert.
Modification of polyamide 6 with hycar ATBN
Authors: Maroušek Vladimír , Svoboda Petr , Králišek Jaroslav
Published: April 2003

The preparation of block copolymers from 6‐caprolactam and a liquid amine terminated butadiene‐acrylonitrile copolymer Hycar ATBN 1300X21 having higher notched impact strength than ordinary poly(6‐caprolactam) was studied. In the polymerization of 6‐caprolactam initiated by an adduct of phosphoric acid with 6‐caprolactam the influence of initiator concentration (0– 50 mol‐%) and Hycar ATBN 1300X21 concentration (0–5 wt.‐%) in the polymerization charge, of polymerization time (4 – 72 h) and of temperature (200–280°C) on the 6‐caprolactam conversion and on the properties of the copolymers formed were followed. Notched impact strength of the block copolymers prepared under optimized conditions was as high as 13.5 kJ·m−2.
Sphärische ionotrope gele carboxygruppenhaltiger cellulosederivate als trägermaterialien für biologische wirkstoffe, IV. Synthese von carboxycellulose und ionotrope gelbildung mit calciumionen
Authors: Heinze Thomas , Klemm Dieter , Loth Fritz , Nehls Irene
Published: April 2003

Natriumcarboxycellulose mit einem Substitutionsgrad bis 0,8 kann durch Oxidation von Cellulose mit einem Polymerisationsgrad im Bereich von 170 bis 1500 mit NaNO2/H3PO4 und anschließender Behandlung mit NaBH4 hergestellt werden. Das Ausmaß der Oxidation steigt mit wachsender Molmasse des Ausgangsmaterials. IR–und NMR‐Untersuchungen zeigen, daß nur das C‐6‐Atom der Anhydroglucoseeinheit oxidiert ist. Die Natriumcarboxycellulosen weisen eine hohe Tendenz zur ionotropen Gelbildung auch in sphärischer Form mit Calciumionen auf. Die mechanisch stabilen Gele werden durch Quellungsuntersuchungen und REM charakterisiert.
Graft polymerization of 4‐vinylpyridine onto cellulosic fibres by the ceric ion method, II. The ph effect
Authors: Leza M. Lourdes , Casinos Ismael , Guzmán Gonzalo M.
Published: April 2003

The effect of pH on the graft polymerization of 4‐vinylpyridine (4‐VP) onto cellulose and on partially carboxymethylated cotton (PCMC) initiated by ceric ammonium nitrate (CAN) in dilute nitric acid was examined. The grafting parameters grafting efficiency (GE), graft yield (G), graft frequency (GF), and ceric ion consumption (Ce(IV)c) were studied as a function of nitric acid concentration. Also the effect of pH on the graft polymerization was examined and the total nitrate ion concentration was maintained high and constant at 0.86 mol/1 by addition of sodium nitrate. Maximum grafting and total conversion occurred at pH 1, but these values were smaller than the ones obtained in the previous case. For comparison some experiments were carried out using ceric sulfate as initiator.
Visco‐Elastic properties of blends of crystalline polymers possessing a weak phase coupling. Studies on blends of poly(ethylene) and poly(oxymethylene)
Authors: Pabst A. , Wendorff J. H.
Published: April 2003

The investigations reported in this paper aimed at evaluating the impact of a weak interfacial strength on visco‐elastic properties in multiphase polymer blends both in the linear and nonlinear deformation regime. Blends of poly(ethylene) and poly(oxymethylene) were used as model systems. The particular choice of the components of the blend was based on the fact that the two components are incompatible, possess strong interfacial energies and thus narrow and weak interfacial layers, and finally that their individual visco‐elastic properties are within the same order of magnitude. This allows to evaluate the contributions of the phase boundaries to the visco‐elastic properties in a transparent way.

We investigated the visco‐elastic properties of blends of various compositions by analyzing the stress‐strain behavior, the dynamical torsional behavior as well as by determinating their cyclic stress‐strain behavior. The experimental finding is that most of the properties studied vary linearly with the composition and are not influenced by the weakness of the interfacial strength–contrary to the expectation. An exception is the elongation at break which varies nonlinearly with the composition and which shows a minimum value at intermediate compositions. The impact of a weak phase coupling on visco‐elastic properties is thus rather limited.
Solution properties of polyacrylic esters. I. Light scattering and viscosity measurements in tetrahydrofuran
Authors: Penzel Erich , Goetz Norbert
Published: April 2003

Dilute THF‐solutions of different fractions of polymers of methyl, ethyl, n‐propyl, n‐, i‐ and t‐butyl, n‐hexyl, 2‐ethylhexyl, and lauryl acrylate, prepared by solution polymerization in benzene, were studied by light scattering and viscosity methods. Poly(acrylic acid) was examined in dioxane. For the different polyacrylic esters the [η]‐Mw‐relations were established and the dependence of the radius of gyration  on the molecular weight was determined.
Eine spektroskopische Methode zur Messung der Ammoniak‐Permeabilität in Polymerfilmen
Authors: Müller Franz Werner , Schiller Kurt , Marx Jörg
Published: April 2003

Es wird eine neuartige spektroskopische Methode zur Messung der Ammoniak‐Permeabilität in transparenten Polymerfilmen vorgestellt. Sie beruht auf dem quantitativen Nachweis des den Testfilm durchdringenden Ammoniaks in einer darunter befindlichen Sensorschicht mit Hilfe der NH3‐empfindlichen Sonde 4‐Nitrophenol. Aus dem Anstieg der Extinktion mit der Zeit (ΔE/Δt) in der Sensorschicht wird die Permeabilität (P) und aus der Verzögerungszeit (lag time (t1)) der Diffusionskoeffizient (D) berechnet. Die Eignung der Methode wird durch Vergleich mit Literaturwerten belegt. Die aus t1 zugänglichen Diffusionskoeffizienten stimmen sehr gut mit denen überein, die mit der Sorptionsmethode gefunden werden.

Die Temperaturabhängigkeiten von P und D in mehr als fünf verschiedenen Polymeren (CDA, PVB, PVAc, PVC und in verschiedenen Polyvinylalkoholen) zeigen, daß Besonderheiten im Temperaturgang der Permeabilität aus dem vom Aufbau des Polymeren stark abhängigen Verhalten der NH3‐Löslichkeit (P/D) resultieren.
Urease immobilized on aminated butyl acrylate‐ethylenedimethacrylate copolymer
Authors: Krajewska Barbara , Leszko Maciej , Zaborska Wieslawa
Published: April 2003

Urease was covalently immobilized on a new acrylic enzyme carrier: aminated butyl acrylate‐ethylenedimethacrylate copolymer. The enzyme retained 56% of its original activity. The properties of the free and immobilized urease were determined and compared. The Michaelis constant was found to be higher for the immobilized urease than for the free one, while maximum reaction rate was lower for the immobilized enzyme. The stability of urease against change in pH was considerably improved by the immobilization. The immobilized urease showed very good storage stability and reusability. Resistance of the enzyme against heat inactivation at 70°C, however, was not found to be improved.
Weld lines in injection moulded polypropylene parts. Mechanical properties morphology relationships
Authors: Wenig Werner , Singh Devinder , Botzen Gerald , Moslé Hüter‐Georg
Published: April 2003

The morphology of polypropylene plaques containing a weld line, has been investigated by x‐ray wide and small angle scattering, light scattering and polarization microscopy. The results are correlated to mechanical values obtained from tensile tests. While the lamellar morphology is of neglectable influence, it is found, that the mechanical properties of the samples are strongly influenced by the spherulitic structure. Clustering of β‐type spherulites and strong morphological inhomogeneities in the vicinity of the weld line are the primary reason for the mechanical weakening of the plaques. The temperature of the mould has a strong effect on the spherulitic structure and thus on the tensile properties of the samples.
Syntheses and properties of UV‐autocurable BTDA‐based polyester multiacrylates. II. Effect of polyol type and reactive monomer
Authors: Chiang Wen‐Yen , Chan Shao‐Ching
Published: April 2003

Several families of UV‐autocurable benzophenone tetracarboxylic dianhydride (BTDA)‐based polyester multiacrylate oligomers containing pendant glycidyl methacrylate (GMA) were synthesized and the effects of acrylic functionality and polyol type on their properties were investigated. The obtained autocurable oligomers possess good pot life and are cured rapidly when exposed to ultraviolet (UV) radiation without the addition of photoinitiator or photosensitizer. Different polyols were used to obtain wide range properties of cured multiacrylate oligomers with a glass transition temperature (Tg) range of 84–130°C. A further modification of the multiacrylate oligomers was obtained by mixing them with reactive monomers having different molecular structure and methacrylic functionality.
The problem of determination of hydroxy groups in poly(oxyethylene) diols by using the phenylisocyanate method
Authors: Novák P. , Ilavský M. , Špašek P. , Bouchal K. , Pavlas P.
Published: April 2003

Traces of potassium acetate present in commercial poly(oxyethylene) diols (Fluka) were shown to catalyze the cyclotrimerization reaction of isocyanates. This reaction interferes with the determination of hydroxy groups by using the phenylisocyanate method. After the removal of potasium acetate (e. g. by means of ion exchangers) the phenylisocyanate method gives reproducible results which can be compared with those obtained by other methods. Reaction conditions suitable for the determination of OH groups in poly(oxyethylene) diols were found.
Alcoholysis of esterlinkages in solution
Authors: Hettrich Wieland , Joel Detlef , Becker Hans , Wehrstedt Carla
Published: April 2003

Poly(alkylene adipate)diols having molar masses of 1500, 2000 and 3000 were stored at temperatures of 25 and 60°C in the presence of low amounts of different alcohols and some polyurethane (PUR) catalysts, such as dibutyltindilaurate (DBTL), dibutyltindiethoxide (DBTEO), dibutyltinoxide (DBTO), and 1,4‐diazabicyclo[2.2.2]octane (DABCO). Alcoholysis was studied using either ethyl acetate (EA) or toluene as solvent. The results were compared with those obtained by examining the behaviour of several dialkyl adipates and ethyl acetate under identical conditions. The alcoholysis in the presence of the tin catalysts proceeds at the same reaction rate without significant decomposition of the catalyst, whereas DABCO is practically inactive. The nucleophilic activity of the alcohols depends on their bulk size rather than their basicity. The resistance of polyalkylene adipates to transesterification increases with the increasing alkyl chain length of diol units in polyester. A partial transesterification of dialkyl adipates takes place too, in spite of ethyl acetate being present in excess.