bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cyclische oligomere in polyestern aus diolen und aromatischen dicarbonsäuren
Authors: Wick Gottfried , Zeitler Herbert 
Published: April 2003

AbstractIn einer Reihe von Polyestern aus Diolen und aromatischen Dicarbonsäuren wurden die cyclischen Oligomeren isoliert und mit Hilfe der Hochdruckflüssigkeitschromatographie quantitativ bestimmt.Der Gehalt an cyclischen Oligomeren hängt von der chemischen Struktur der Polyester und vom Kondensationsverfahren ab. Hauptkomponente ist das cyclische Dimere, bei Poly(ethylenterephthalat), Poly(1,4‐dimethylencyclohexanterephthalat) und Poly(1,4‐dimethylenbenzolterephthalat) aus Ringspannungsgründen das cyclische Trimere.Bei technischem Poly(1,4‐dimethylencyclohexanterephthalat) gelang eine Auftrennung der stereoisomeren cyclischen Oligomeren, die durch die Verwendung eines trans/cis‐1,4‐Cyclohexandimethanol‐Gemisches entstehen.Die cyclischen Oligomeren der Copolyester mit Diolethern enthalten bei niedrigem Modifizierungsgrad nur einen Dioletherrest.
Behaviour of chemically modified cottons towards thermal treatment. Part 1: Partially carboxymethylated cotton
Authors: Hebeish A. , Khalil E. M. , El‐Rafie M. H. , Abdel‐Hafiz S. A. 
Published: April 2003

AbstractMill scoured and bleached cotton fabric, alkali treated cotton and partially carboxymethylated cottons having 34, 50 and 68 milliequivalent/100 g cellulose were subjected to thermal treatments. The latter were carried out at different temperatures for different durations of time. Chemical degradation of the substrates brought about by thermal treatment was assessed by copper number, carboxylic groups and degree of polymerization whereas deterioration was measured by tensile strength and elongation at break. It was found that the partially carboxymethylated cottons underwent higher degradation than the original (mill scoured and bleached) cotton, that the magnitude of deterioration of the substrate was determined by the previous chemical treatments and that the higher the carboxymethyl content the greater the degradation and deterioration of the substrate.
Analyse der bei den chemischen reaktionen von vernetzten makromolekularen stoffen gewonnenen zeit‐umsatz‐kurven
Authors: Matějíček Alois , Seidl Josef , Krejcar Emil , Matyáš Josef 
Published: April 2003

AbstractEs wird eine Näherungsformel für die bei chemischen Reaktionen von vernetzten makromolekularen Stoffen gewonnenen Zeit‐Umsatz‐Kurven mit Hilfe der Beziehung α = 1 − exp (a1τa2) vorgeschlagen. Es wird die Berechnung der Geschwindigkeitskonstanten und der Diffusionskoeffizienten angegeben, die sich auf die Diffusion der reagierenden flüssigen Komponenten ins hydrophobe Polymergerüst beziehen. Die Berechnung wird für Kugel‐, Tafel‐ und Zylinder‐Formen des reagierenden, vernetzten makromolekularen Stoffes durchgeführt.
Shape of spherulitic boundaries
Authors: Varga József 
Published: April 2003

AbstractA quantitative description of shape of spherulitic boundaries is given in the present publication for the case of two‐dimensional spherulitic crystallization. Shape of the spherulitic boundaries depending on time of formation of nuclei and relative growth rate of spherulites corresponds to one of the following: circular, straight line, hyperbolic line, limacon of Pascal or a curve describable by a fourth degree equation. The deduced formulae are illustrated by experimental data obtained in spherulitic crystallization of α‐ and β‐modifications of polypropylene.
Die polymerisation von lactamen, 50. Die polymerisation von 8‐octanlactam in gegenwart von wasser in niedrigen konzentrationen
Authors: Prokopová Irena , Černý Jiří , Kondelíková Jaroslava , Králíček Jaroslav 
Published: April 2003

AbstractEs wurde die Polymerisation von 8‐Octanlactam in Gegenwart von Wasser in Konzentrationen von 0,026–0,95 mol‐% bei 250°C verfolgt. Die gefundenen kinetischen Daten zeugen von verschiedenen Funktionen des Wassers im Konzentrationsbereich bis 0,35 mol‐% und bei höheren Konzentrationen. Mit Rücksicht auf die Ergebnisse der Endgruppenanalyse der Polymeren, die ohne Zusatz von Wasser und weiteren Initiatoren (sog. Autopolymerisation) dargestellt wurden, wird für die Polymerisation von 8‐Octanlactam in Gegenwart von Wasser in Konzentrationen bis 0,35 mol‐% ein kationischer Mechanismus vorgeschlagen.
Characteristics of cylindritic crystallization of polypropylene
Authors: Varga József 
Published: April 2003

AbstractCharacteristics of cylindritic crystallization of polypropylene were studied by means of optical microscopy. It has been shown that a distinct structural memory effect is observed during the cylindritic crystallization. This memory effect can be attributed to thermal stability of row nuclei giving rise to the cylindritic crystallization. Negative or mixed type cylindrites are formed depending on the crystallization temperature (Tc > 410 and Tc < 410 K, respectively). Cylindrites obtained by stepwise crystallization are constructed of segments with different optical characteristics and melting points. Boundary lines of parabolic, hyperbolic, ellipsoidal or linear shape can be developed between the cylindrites and spherulites formed parallel. Equations describing the boundary lines are given in the present publication.
Neue Bausteine für das Diisocyanat‐Polyadditionsverfahren, III NCO‐Trimerisate durch Phasentransferkatalyse
Authors: Richter Roland , Müller Peter , Wagner Kuno 
Published: April 2003

AbstractDie Erkenntnisse der Fest‐Flüssig‐Phasentransfer‐Katalyse, die im letzten Jahrzehnt zu einem festen Bestandteil der präparativen organischen Chemie geworden ist, werden auf die seit langem bekannte Nutzung der basischen Alkalimetallsalze als Trimerisationskatalysatoren für Isocyanate übertragen. Durch Komplexierung mit Hilfe von offenkettigen Polyethylenglykolen, die im Mittel 5 bis 8 Ethylenoxideinheiten enthalten, gelingt es erstmals, Kaliumacetat als löslichen und hochaktiven („Anionenaktivierung”︁) Trimerisationskatalysator bei der Herstellung von Lackisocyanaten mit Isocyanurat‐Struktur einzusetzen.
Chemical modification of polystyrene, III. Electrophilic substitution of polystyrene with aromatic anhydrides
Authors: Biswas Mukul , Chatterjee Shakuntala 
Published: April 2003

AbstractPolystyrene has been chemically modified by Friedel‐Crafts acylation reaction with trimellitic anhydride in the presence of anhydrous aluminium chloride as catalyst. The product has been characterized in respect of its structure and physicochemical properties by measuring its total capacity, thermal stability and the behaviour to pH metric titration. The thermal characteristics of the trimellitic anhydride modified polystyrene have been compared with the same for phthalic anhydride and pyromellitic dianhydride modified polystyrene in the light of their structural characteristics.
Molekulargewichtsverteilung und Verzweigungen der Prepolymeren von iso‐Diallylphthalat
Authors: Błȩdzki Andrzej , Kostański Krzysztof 
Published: April 2003

AbstractDie Polymerisation von iso‐Diallylphthalat (iso‐DAP) wurde bei verschiedenen Temperaturen zwischen 80°C und 285°C verfolgt und die vor dem Gelpunkt gebildeten Prepolymeren in Methanol isoliert. Mittels Gelchromatographie wurde die Molekulargewichtsverteilung der Prepolymeren bestimmt. Anhand des Doppelbindungsgehaltes und des Molekulargewichtes vor und nach der Hydrolyse konnte der Verzweigungsgrad der Prepolymeren berechnet werden.Es konnte gezeigt werden, daß die Struktur der gebildeten Prepolymeren sehr stark von der Polymerisationstemperatur und vom Umsatz abhängt.
Analyse von Ablagerungen auf Werkzeugoberflächen (Plate‐out) bei der Extrusion von PVC
Authors: Braun D. , Bezdadea E. 
Published: April 2003

AbstractEs wird eine Analysenmethode zur Bestimmung der Zusammensetzung des bei der Extrusion von PVC auf verschiedenen Werkzeugteilen abgelageerten Materials beschrieben. Die Methode wurde zunächst mit dem Ausgangscompound einer plateout‐trächtigen Rezeptur ausgearbeitet. Die Trennung der einzelnen Komponenten erfolgte anhand einer Löseextraktion des Materials in Tetrahydrofuran (THF). Die in THF nicht löslichen Teile (TiO2, CaCO3, etc.) wurden gravimetrisch bestimmt und die einzelnen Komponenten chemisch und spektroskopisch (Atom‐Absorption‐Spektroskopie, Röntgen‐Fluoreszenz, Massen‐Spektroskopie) identifiziert und abgetrennt. Die löslichen Teile (PVC, Weichmacher, Gleitmittel, etc.) wurden qualitativ mit Hilfe der Gel‐Chromatographie identifiziert und durch NMR‐Spektroskopie quantitativ bestimmt.
Polymerisation von Vinylchlorid bei Atmosphärendruck 1. Polymerisationssysteme zur Herstellung von U‐PVC
Authors: Braun D. , Holzer G. 
Published: April 2003

AbstractEs wird die Polymerisation von gasförmigem Vinylchlorid (VC) im Temperaturbereich von 45°C bis 60°C mit Kaliumperoxodisulfat als Initiator bei Atmosphärendruck beschrieben. Die Menge des gebildeten Polymeren (sog. U‐PVC) im Verhältnis zur Reaktionsdauer hängt vom Monomerdurchsatz ab.Die Polymerisationsgeschwindigkeit kann sowohl durch Erhöhung der Initiatorkonzentration als auch der Temperatur gesteigert werden. Mit dem Redoxsystem K2S2O8/Na2SO3/Cu2+ ist es möglich, bei sonst konstanten Bedingungen im Temperaturbereich von 0°C bis 20°C zu polymerisieren.Mittels transmissionselektronenmikroskopischer (TEM) Untersuchungen wurde die Größe und die Größenverteilung der Teilchen in Abhängigkeit von der Polymerisationszeit und Temperatur ermittelt.
Transcrystallinity in injection molded polypropylene glass fibre composites
Authors: Misra A. , Deopura B. L. , Xavier S. F. , Hartley F. D. , Peters R. H. 
Published: April 2003

AbstractThe occurrence of transcrystallinity in polypropylene in the presence of glass fibres under stress was studied. An experiment was designed on a hot‐stage polarizing microscope in which it was found that slight mechanical stress at the fibre polymer interface gives rise to surface nucleation and growth of transcrystalline regions. Composites of polypropylene with various concentrations of glass fibres were prepared by injection molding. The observed transcrystalline regions in the injection molded samples were attributed to the availability of sufficient inherent internal stresses. Moreover, an increase in fibre concentration was found to enhance transcrystallinity. This indicated that the internal stresses were increased with increasing fibre population.
Synthese und Eigenschaften eines chelatbildenden Austauschers mit N,N′‐bis‐(2‐hydroxybenzyl)‐ethylendiamin als Ankergruppe auf der Basis von Polystyrol
Authors: Djamali M. G. , Lieser K. H. 
Published: April 2003

AbstractDie Synthese eines neuen Polystyrolaustauschers mit N,N'‐bis‐(2‐hydroxybenzyl)‐ethylendiamin als Ankergruppe wird beschrieben. Die Ankergruppe wird durch Umsetzen von Salicylaldehyd mit Ethylendiamin zu N,N'‐ethylen‐bis‐(salicylaldimin) = “Salen” und Hydrierung des “Salen” dargestellt. Polystyrol wird nitriert, reduziert, diazotiert und mit N,N'‐bis‐(2‐hydroxybenzyl)‐ethylendiamin gekuppelt. Der Austauscher wird durch Bestimmung des Ankergruppengehaltes sowie der Kapazität, Messung der Austauschgeschwindigkeit und Bestimmung der Verteilungskoeffizienten für Au3+‐, Pd2+‐, Pt4+‐, Cu2+‐ und Ni2+‐Ionen charakterisiert.
Radiation initiated grafting on fluoro polymers II. Grafting of N‐vinylpyrrolidone on copolymers of vinyl fluoride and vinylidene fluoride by accelerated electrons
Authors: Vierkotten Detlev , Ellinghorst Guido 
Published: April 2003

AbstractThe radiation initiated grafting of N‐vinylpyrrolidone (NVP) onto copolymers of vinyl fluoride/vinylidene fluoride (VF/VF2) with compositions of 75/25 mol‐%, 50/50 mol‐% and 20/80 mol‐% VF/VF2 has been investigated. The active species, initiating the grafting, have been created by accelerated electrons (160 keV) applying preirradiation technique in vacuo. The time conversion curves present a characteristic temperature dependence. Increasing grafting temperature rises the initial grafting rate. The final (saturation) grafting yield increases with temperature up to 333 K, and then declines. This behaviour was described by the influences of glass transition on the rate of termination in the semicrystalline trunk polymers. The grafting rate (at constant irradiation dose and grafting temperature) decreases with increasing VF2 content in the copolymers. The reason is discussed by means of a semiquantitative mathematical analysis of the graft kinetics applying “non‐steady‐state”‐conditions. The grafting rate does not depend on dose rate, but strongly depends on irradiation dose passing a maximum. This maximum has been interpreted by means of “Differential‐Interference‐Contrast”‐microscopy. The enthalpies of melting ΔHm of the semicrystalline copolymers decrease after grafting with increasing grafting yield. This change is due to the partial destroying of crystalline regions in the trunk copolymers caused by stresses arising from grafted polymer chains. The membrane resistance of films grafted through is <10 Ω cm2. The membranes proved to be permeable for urea.
Chemistry and application of organic isocyanates VI.. Conversion of tolylene‐2,4‐diisocyanate into biuret and urea derivatives by means of Na2SO4. 10H2o
Authors: Lesiak Tadeusz , Ciemniak Grażyna , Czerwiński Wojciech 
Published: April 2003

AbstractThe attempts of conversion of tolylene‐2,4‐diisocyanate by means of water contained in Na2SO4. 10H2O have been described. It has been shown that the reaction products are mixtures of oligomers with biuret or urea basis. By means of mass spectroscopic and gel permeation chromatographic analyses, the scheme of the mentioned formation of prepolymers has been proposed. On the basis of the results of physico‐chemical measurements, the influences of temperature and molar ratios of the reagents on the properties of products have been interpreted.
On the temperature dependence of polyolefin inhibited oxidation parameters
Authors: Bogaevskaya T. A. , Shlyapnikov Yu. A. 
Published: April 2003

AbstractOxidation of atactic polypropylene stabilized with phenyl‐naphthyl‐amine has been studied in the temperature range of 80–200°C. The induction period observed in the presence of inhibitor does not obey the Arrhenius law over all the temperature range studied.
Physical aspects of synergism in photostabilization of polymers
Authors: Ivanov V. B. , Lozovskaya E. L. , Efremkim A. F. , Shlyapintokh V. Ya. 
Published: April 2003

AbstractThe mechanism of synergism in mixtures of UV‐absorbers and radicals scavengers of peroxide decomposers is considered. The synergism is explained by diffusion of the antioxidant from the bulk of the polymer protected by UV‐absorber towards the surface layer where the photoreaction proceeds. It is also shown that it is possible to obtain the synergistic effects using additional stabilizing or nonstabilizing substances, which change the solubility of a given stabilizer and the mode of its distribution in polymeric matrix.
Einfluß unterschiedlicher strahlungssysteme auf das alterungsverhalten von hochpolymeren, exemplarisch dargestellt anhand der änderung des topochemischen aufbaues einiger polyäthylen‐werkstoffe. Strahlungsphysikalische grundlagen und eingesetzte bewitterungsverfahren.
Authors: Boxhammer J. 
Published: April 2003

AbstractThe requirements are outlined which are made on artificial radiation sources for time accelerating weathering. The general radio‐physical data of an especially developed metal halide lamp are indicated, the so‐called Ultratest radiation, and are compared to the filtered Xenon radiation so far used in weathering machines.Information is given on specific radio‐physical and thermical conditions for certain comparing tests in machines at samples level.
Untersuchung der “werkstoffwirksamkeit” unterschiedlicher strahlungssysteme und bewitterungsverfahren
Authors: Müller Klaus 
Published: April 2003

AbstractBy means of differential IR‐spectroscopic analysis (“layer by layer”) of different types of polyethylene and additional testing of the mechanical behaviour of these materials the “material efficiency” of different natural and artificial weathering methods are discribed exemplary. The combination of IR‐spectroscopic analysis and microfractografic test results gives informations about the ageing progress in time and in the bulk of the polymer. In this respect the discussed material orientated method seems to be suitable for a quantitative estimation of the simulation quality of artificial weathering methods. Furthermore the method allows the comparative assessment of the degradation rate of different polymers in consideration of inhomogeneities as a result of production and/or processing (for example: the gradient of crystallinity) as well as the comparative estimation of natural weathering conditions (for example in respect of the material efficient period of weathering time).
Einfluß von stabilisatoren auf freibewitterung von PVC
Authors: Erben F. , Veselý R. 
Published: April 2003

AbstractThe resistance of hard PVC film samples to aging by natural weathering has been investigated to enable comparison of efficiency of various PVC stabilizing additive types and their combinations. All the film samples contained the same HCL acceptor, a sulfur free organotin stabilizer, and additional stabilizers of their combinations: antioxidants (phenolics ‐ Irganox 1010 and Antioxidant 2246, phosphites ‐ Irganox 1222 and Antioxidant 6), the quencher Irgastab 2002 and epoxides soyabean oil.
About one possibility to investigate the synergism between PVC ‐ stabilizers statistically
Authors: Mikaelian M. 
Published: April 2003

AbstractThe possibility of studying the presence of synergism between stabilizers was treated, by applying experimental design, which is suitable for studying mixture's properties. The method of “pseudocomponents” was used with the particular three‐component stabilizing system ‐ calzium‐zinc complex, tris‐(nonyl‐phenyl)phosphite and α‐Phenylindole. As thermal stability criteria the induction time, colour stability and dynamic thermal stability in Brabender Plastograph were chosen.Regression relationships in the form of canonic equations of third order were obtained. Using the derived equations and computer, "composition‐properties" diagrams were plotted.The abovementioned diagrams described adequately the stabilizing effect of the system in the investigated area of stabilizer concentrations, and it was shown that optimum results were obtained when about 20 percent of the primary stabilizer were replaced by 10 percent of each co‐stabilizer. This synergistic effect is most pronounced for the initial colour of the PVC‐compound.
Einfluß der verarbeitung auf die wirksamkeit der stabilisierungs‐systeme in polypropylen
Authors: Čaučik P. , Považancová M. , Durmis J. , Karvaš M. 
Published: April 2003

AbstractStability of systems can be influenced by processing conditions. Extent of influence is dependend not merely upon processing conditions, but also used stabiliser formulations. There were investigated the systems, which contained as a photostabiliser various hindered amine compounds and 2‐hydroxy‐4‐octyloxybenzophenone. There was investigated the effect on photostability in accelerating aging in Xenotest 450/uptake of carbonyls/. From results can be concluded that hindered amines much better protect polyolefines even after processing at higher temperatures than commercialy known UV‐absorber‐2‐hydroxy‐4‐octyloxybenzophenone.
Spannungsrissverhalten von PMMA nach freibewitterung
Authors: Hennig J. 
Published: April 2003

AbstractThe presented results indicate that molecular decomposition of PMMA after 5 years outdoor weathering can be clearly detected especially on both surfaces, but this decomposition stays within a range where long term mechanical properties, e. g. creep strength and crazing measured on the weathered samples in air, are not remarkably affected. More pronounced deviations from the original state can be observed with the elongation at crazing onset and in the behaviour against organic solvents, e. g. in the system PMMA/hexanol time and stress for crazing onset are reduced for the 5 years weathered material compared with the original sample. For practical situations this means that precautions must be taken when applying corrosive media in contact with weathered plastics, especially if it concerns a polymeric material which is less resistent against photooxidative decomposition than PMMA.
Witterungsbeständige hartpolyvinylchloridmischungen
Authors: Kabaiwanov Ch. , Mikaelian M. , Dimitrova El. 
Published: April 2003

AbstractSome aspects related to the assessment of rigid PVC compounds for outdoor exposure suitability are discussed.For compound elaboration bulgarien K‐value 64 PVC is used, as well as modifiers based on chlorinated polyethylene, EVA copolymer and stabilizing systems, based on barium‐cadmium compounds.The sensibility and the information given by some of the common used physical and mechnical properties as criteria for suitability assessment are used: resistance at tensile stress, elongation at break, impact resistance, colour and residual thermical resistance of the surface layer, submited at ageing.The impact resistance is determined using samples with round apperture and this resistance is compared with the resistance of notched samples. The colour variation is determined by the means of apparaturs.The results of artificially up to 600 h in weatherometer and up to 1 year for naturally aged samples are discussed.A well determined difference in the character of the colour during the artificial ageing and the natural one is established.The results of the above mentioned experiments were used for selection of compounds intended to be used for outdoor wall coverings production.
Investigation on polyethylene films of controllable service life
Authors: Bálint G. , Halász A. , Iring M. , Tüdös F. 
Published: April 2003

AbstractThe effect of a special additive containing stabilizer and sensitizer groups was studied in thermal and photooxidation of polypropylene.In thermooxidation, the induction period of oxygenz absorption decreased, and its rate increased with the increase of the amount of the additive. In photooxidation, however, the shortest induction period and highest rate of carbonyl formation can be achieved at an optimal additive concentration.The final molecular mass of the samples after irradiation till the spontaneous rupture falls in the range of moldecular mass consumable for the microbes.On the basis of the results, it seems to be possible to stabilize the polymer during processing and storage, and sensitize under solar irradiation with the same additive.
Möglichkeiten der regelung der bewitterungsstabilität von PE
Authors: Erben Franišek , Veselý Rudolf 
Published: April 2003

AbstractThe results of weathering aging tests of foil samples are described by some examples of stabilization and fast degradation of branched polyethylene. The results confirm that the life period of these polymers can be affected considerably in a positive or negative way by controlling the concentration of appropriate additives. The investigations were carried out on samples of LDPE Bralen RA 7–20 and RA 2–19. The stabilizers towards weathering effects were Cyasorb UV 531, Tinuvin P, Benazol P, Tinuvin 622, and Dastib 845 (UV‐absorber). Weston 618 and Irganox 1076 were antioxidants and Ecolyte E, Anthrachinon and its derivatives were taken as prodegradants.
Untersuchungen zur mechano‐chemischen Synthese durch Schwingmahlen einiger Eisen‐ und Mangankomplexe unter Verwendung von ϵ‐Caprolactam und Poly(ϵ‐caprolactam) als Liganden
Authors: Simionescu Cristofor I. , Opera Cleopatra Vasiliu , Negulianu Claudia 
Published: April 2003

AbstractIn dieser Arbeit wird eine Vergleichsuntersuchung bezüglich der mechano‐chemischen Synthese durch Schwingmahlen einiger Eisen‐ und Mangankomplexe unter Verwendung von ϵ‐Caprolactam und Poly(ϵ‐caprolactam) als Liganden durchgeführt. Die erhaltenen Produkte werden durch Elementaranalyse, IR‐Spektroskopie, thermogravimetrische Analyse und thermomechanische Kurven gekennzeichnet. Der Mechanismus der Synthese und die Struktur der erhaltenen Komplexe werden besprochen.