bluuebunny/crossref_metadata_2025_split huggingface dataset:
UNTERSUCHUNG PRAXISRELEVANTER EIGENSCHAFTEN VON PP—BLENDS
Authors: Kloos Friedrich , Strouk Hervé , Uebe Rudolf , Heufer Gert 
Published: April 2003

AbstractThe influence of rubber composition in high impact modified polypropylene blends was investigated with respect to some practical properties in automotive applications. The properties were weld line strength, surface gloss, the optical impression of weld lines and weatherability. Blends with an impact modification of EPDM‐rubber show a slightly better performance in weld line strength and optical impression of weld lines in the surface, whereas blends which are modified by an EPDM‐HDPE‐masterbatch have a higher surface gloss and an improved stability against wheathering. It could be shown that these properties depend on the skin morphology which is different for the two kinds of blends.
Development and characterization of a biocompatible OH‐modified copolymer based on polyurethane
Authors: Anderheiden Dirk , Brenner Otto , Klee Doris , Kaufmann Robert , Richter Horst A. , Mittermayer Christian , Höcker Hartwig 
Published: April 2003

AbstractDifferent polyurethanes were synthesized by varying the diol as well as the diisocyanate components and chain extenders. Polyurethanes with OH‐groups were obtained by photo‐ and thermoinitiation of the radical polymerization of hydroxy alkyl acrylates in the presence of the polyurethanes. The polymers were evaluated with respect to their biocompatibility by measuring the cell spreading, the rates of DNA‐ and protein synthesis and the swelling behaviour. The differences in the surfaces and the bulks between the selected basic polyurethane and the functionalized modification were determined and characterized by XPS, FTIR‐ATR and 13C‐FT‐NMR‐spectroscopy. The mechanical data of Tecoflex EG 60D® and Pellethane 2363–80AE® were compared with the data of the synthesized polyurethanes.
Hydrostatic extrusion rate relaxation in polyethylene, polyoxymethylene, and their blends. The relaxation of viscosity and compressibility in polymeric solids
Authors: Schaffner F. , Vinson J. , Jungnickel B. ‐J. 
Published: April 2003

AbstractIt is reported on precision measurements of the hydrostatic extrusion rate of polyethylene, polyoxymethylene, and their blends in dependence on pressure and temperature. It turns out that the extrusion rate change after a sudden pressure change consists of an immediate response and a second one which relaxes toward its new equilibrium value with a time constant of several minutes. Both relaxation components have different sign. Increasing pressure causes a decrease of the extrusion rate by the slow relaxation step. Relaxation strength and inverse time constant of this relaxation component exhibit a maximum at a certain pressure. The overall relaxation behaviour is assumed to be caused by a superposition of the competing effects of free volume relaxation in the amorphous parts in these semicrystalline polymers, of compressibility relaxation, of volume recovery in the extruded strands, and of viscosity changes in the sample materials during the pressure induced plastic deformation of both the amorphous and the crystalline phases.
Wettability of poly (2,2′‐bithienyl‐5,5′‐diyl) layers.
Authors: Niemitz Matthias , Koßmehl Gerhard 
Published: April 2003

AbstractThe electrochemical polymerization of 2,2′‐bithienyl (BT) leads to the formation of redox active polymer layers on the anode. The wettability of these poly (2,2′‐bithienyl‐5,5′diyl) (PBT) layers was studied as a function of the experimental conditions (concentration, current density, film thickness and the potential of the polymer electrode). A drastic change in the wettabilty was observed within the redox process.
RADIKALISCHE COPOLYMERISATION VON ETHYLEN MIT SALZEN DER METHACRYLSÄURE UNTER HOCHDRUCK
Authors: Kredel Udo , Luft Gerhard 
Published: April 2003

AbstractIn order to prepare ionomers, the radical copolymerisation of ethylene with salts of methacrylic acid was investigated. The polymerisation tests were performed in a continuously operated stirred autoclave at 1800 bar, 190 to 240°C and a residence time of 60 sec. The concentration of methacrylate in the feed was varied between 0, 3 and 3, 4 wt%. For comparison ethylene homopolymers were prepared.From the polymerisation tests the conversion was determined. The resulting copolymers were analysed for their composition to calculate the reactivity ratios. Furthermore density, crystallinity and melt flow index were measured.
Properties of a single chain embedded into a polymer matrix of varied thermodynamic quality and density
Authors: Olaj Oskar Friedrich , Zifferer Gerhard , Lantschbauer Wolfgang 
Published: April 2003

AbstractThe properties (squared dimensions, anisotropy, numbers of intra‐ and intermolecular contacts) of a single five‐way cubic lattice chain embedded into an environment (matrix) of chains of the same length n = 50 were evaluated as a function of matrix volume fraction (matrix density) v and intermolecular interaction between the matrix polymer and the minority chain segments, characterized by a parameter ϕ. No convincing evidence was found for the occurrence of a coil‐globule transition in the range of matrix densities (v ≤ 0.7) and repulsive interactions between matrix and minority chain (ϕ ≤ 0.2) investigated. For moderate attractive interaction (ϕ ≈ −0.17) a compensation of the chaincompressing action of the matrix and the chain‐expanding interaction with the matrix was observed resulting in a zero‐dependence of the size and shape of the minority chain on matrix density. It further turned out that there are fixed relations among the various size and shape data irrespective of the specific combination of matrix density and thermodynamic interaction by which a particular polymer dimension is produced. These interrelations are fairly the same as those evaluated for isolated chains the size of which is varied by an intramolecular energy parameter ϕi.
NIEDER‐ UND HOCHMOLEKULARE RADIKALKATIONEN VON CHINOXALINDERIVATEN
Authors: Quarg Gunter 
Published: April 2003

AbstractChinoxaline dienen als Sensibilisatoren in der Farbphotographie und bei verschiedenen photoinduzierten Polymerisationsprozessen. Es wird versucht, durch Erzeugung von monomeren Chinoxalin‐Radikalkationen und von Polymeren mit Seitenketten von entsprechender Struktur Modelle für die Untersuchung des zugrundeliegenden Wasserstoffübertragungs‐Prozesses zu gewinnen.Die durch Reduktion oder durch Bestrahlung mit UV‐Licht in Eisessig gebildeten Radikalkationen verschiedener Chinoxaline werden durch ihre Spektren und ihr Zerfallsverhalten charakterisiert.
MATERIAUX TRIPHASIQUES ALVEOLAIRES POLYMERE / CHARGE / LIQUIDE OU GAZ. Préparation de Matériaux triphasiques Polystyrène / billes de Verre / Eau ou Air
Authors: Frischinger Isabelle , Balard Henri , Riess Gérard 
Published: April 2003

AbstractNew three phases composite materials made of glassbeads as filler, water as liquid dispersed phase and polystyrene as matrix were obtained by polymerization of a water in oil emulsion formed by water dispersed in styrene in which glass beads are added. For this purpose glass beads have to be modified by silanization by a coupling agent 3‐(Trimethoxysilyl)propylmethacrylate (TPM) or a silane Octadecyltrichlorosilane (ODMS), in order to prevent the wetting of the glass by water. Only low coverage of the glass surface by the coupling agent (0,05% of TPM) are convenient for the preparation cellular materials having good mechanical properties. At higher coverage ratio, strong hydrophobic glass beads are obtained which destabilize the water / styrene emulsion and lead to macroporous products. Study of the rheology of the filled emulsion appears to be the more simple and more sensitive method to determine the level of wettability of the glass bead by the emulsion which is the most significant parameter for the preparation of such three phases composite materials. Composite materials made of glass beads, air and polystyrene are simply obtained by evaporation of water under vacuum.
Verträgliche Polymermischungen durch Säure‐Base‐Wechselwirkungen
Authors: Siol Werner , Terbrack Ulrich 
Published: April 2003

AbstractPoly‐2‐ethyl hexylacrylate and the copolymer of 30% b. w. of styrene and 70% b. w. of hexyl methacrylate are incompatible per se. Modification of the polyacrylate by incorporating acrylic acid and of the styrene containing copolymer by incorporating aminogroups render those polymers compatible. all blends of interest show a cloud point on heating. Polymer compatibility increases as the content of acid and basic groups in the polymer increases. Substantial inequality in the acid base ratio will cause asymmetry in the phase diagram especially so when there are not too many interacting groups present.
Gas sorption in poly(butylene terephthalate). A critical test of the influence of molecular gas data
Authors: Schultze J. D. , Zhou Z. , Springer J. 
Published: April 2003

AbstractTo test the molecular parameters concerning gas sorption in polymers, the concentration of CO2, N2O, CO, N2, CH4 and the noble gases Ne, He in glassy poly(butylene terephthalate) films (PBTP) has been studied gravimetrically with a recording microbalance at 25°C. The sorption isotherms exhibit downward curvature to the pressure axis. As neither solubility nor adsorption can explain the experimental results, analysis was carried out based on the dual‐sorption model: gas dissolution and microvoid filling are considered as independent sorption mechanisms. The parameters of the dual‐sorption model for the mentioned penetrants are determined. The results indicate that for parameter correlation the Lennard‐Jones potential parameters give a rough idea, but size exclusion of gases in small diameter microvoids is proposed and special chemical interactions must be considered.
CHARAKTERISIERUNG VON TRIGLYCIDYLISOCYANURAT
Authors: Vargha Viktoria 
Published: April 2003

AbstractThe synthesis of triglycidyl isocyanurate resulted two forms of the compound which were separately characterized by chemical analysis, thin‐layer chromatography, vapour‐pressure osmometry, UV‐, IR‐, 13C‐NMR spectroscopy. One form sems to be equal with one diastereomer, the other one contains two more components.
Synthesis and characterization of new urethane‐acrylic polymers
Authors: Rajalingam P. , Radhakrishnan Ganga 
Published: April 2003

AbstractA new class of urethane‐acrylic monomers was synthesized from diisocyanates such as toluylene diisocyanate (TDI) and hexamethylene diisocyanate (HMDI), unsaturated alcohols like hydroxyethyl methacrylate (HEMA), hydroxypropyl methacrylate (HPMA), and saturated alcohols such as stearly alcohol and decanol. The monomers were characterized by IR and NMR spectroscopy. Urethane pendent acrylic polymers, obtained by polymerizing these monomers, were characterized by IR, solubility viscosity, and thermal studies. The thermodynamic parameters for the degradation were calculated and a probable degradation mechanism is proposed.
Glass cloth reinforced composites of castor oil based polyurethanes and epoxy resin
Authors: Suthar Bhikhu 
Published: April 2003

AbstractPrepolyurethanes were obtained by reacting the hydroxyl functionality of castor oil with diisocyanates, namely toluene‐2,4‐diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, and 4,4′‐diphenylmethane diisocyanate, respectively. Homogeneous mixtures of prepolyurethanes and epoxy resin (prepared from bisphenol F in alkaline medium) were prepared in acetone containing 1,3‐propanediamine as curring agent. Glass reinforced laminates were prepared by interacting PU/epoxy resin mixtures on glass cloth through compression moulding. The laminates were characterized by chemical resistance to solvents, flexural strength, izod impact strength, and Rockwell hardness. The variation of electrical conductivity σ with temperature was found to confirm with the empirical relation σ = σ0 exp(−E/2kT).
Bestimmung der teilchengrößenverteilung von polymer‐dispersionen durch ultrazentrifugation bei unterschiedlichen wellenlängen
Authors: Lorenz O. , Haulena F. , Reiners A. , Roeder D. 
Published: April 2003

AbstractZur Bestimmung der Teilchengrößenverteilung (TGV) von Polymer‐Dispersionen mit Teilchendurchmessern D < 40 nm durch Ultrazentrifugation sind im allgemeinen Konzentrationen erforderlich, bei denen Wechselwirkungen zwischen den Teilchen auftreten. Diese Wechselwirkungen verursachen eine Verschiebung der TGV zu kleineren Durchmessern und bewirken außerdem eine Verengung der TGV. Um niedrige Konzentrationen zu verwenden, bei denen keine Wechselwirkungen auftreten, ist es zweckmaßig, Messungen unter Verwendung weitgehend monochromatischen UV‐Lichtes durchzuführen, da nach der Mieschen Theorie die spezifische Trübung mit der Frequenz des Lichtes zunimmt.Polystyrol‐, Poly (methylmethacrylat)‐, Poly(n‐butylacrylat‐co‐methylmethacrylat)‐und Polyurethan‐Dispersionen, die durch anionische Netzmittel bzw. eingebaute Anionen (Polyurethan) stabilisiert waren, wurden unter Verwendung von Licht der Wellenlänge 546, 436, 365 bzw. 313 nm untersucht. Es zeigte sich, daR insbesondere bei 313 nm niedrige Konzentrationen (≤ 1 g/l) verwendet werden konnten. Die ermittelte TGV war praktisch unabhängig von der Wellenlänge, auch wenn eine vergleichsweise breite unimodale Verteilung vorlag. Der Fehler, den eine konsumptive Absorption im UV‐Bereich hervorruft, kann demnach vernachlässigt werden. Bei Verwendung höherer Konzentrationen ließ sich durch Zugabe von Natrium‐Dodecylsulfat eine Herabsetzung, aber keine völlige Eliminierung der Wechselwirkungen zwischen den Teilchen erreichen.
Synthesis and application of thermosensitive microcapsules containing azo groups
Authors: Nuyken Oskar , Dauth Jochen , Pekruhn Wolfgang 
Published: April 2003

AbstractIn view of applying thermolabile microcapsules with azo groups as thermosensitive sites it was necessary to study the preparation and the thermal behaviour of two reactive, symmetrical azo monomer‐compounds and model compounds. They are thermally and photochemically instable and the kinetics of their decomposition is of first order, comparable to that of AIBN.Azo group‐containing polyamides and polyureas were prepared by interfacial polycondensation reaction from ethylendiamine, 1,6‐hexamethylenediamine, diethylenetriamine and azo monomer‐compounds.These polymers were used to prepare thermosensitive microcapsules. Favourable conditions were found to obtain microcapsules of uniform size, in a high yield, and with good properties in thermo‐transfer‐print.
Microemulsion polymerization of vinyl acetate
Authors: Donescu Dan , Anghel Dan , Gosa Kristiana , Balcan Marieta 
Published: April 2003

AbstractVinylacetate (VAc) was polymerized with ammonium persulfate in microemulsions prepared from VAc, sodium dodecyl sulfate, n‐propanol and water. The polymerization rates were smaller than those in emulsion. The reaction orders versus the initiator and tenside concentration were 0.9 and −0.5, respectively. The polymerization rate and molecular weights decreased by increasing the surfactant and the cosurfactant concentrations. By cooling the finally obtained microemulsions, a polymer solution coacervation took place.
Filled compounds of the β‐modification of polypropylene
Authors: Varga József , Tóth Ferenc Schulek 
Published: April 2003

AbstractPossibilities and thermal preconditions of the preparation of filled β‐PP composites were studied. Two types of mineral fillers (chalk and talc) were found considerably different. Chalk, as a weak α‐nucleating agent, exerts minimum influence on the rate of crystallization, on the polymorphic composition, and on the size of spherulites formed. Consequently, chalk‐filled β‐PP composite products can be manufactured in a wide range of composition. On the contrary, talc is a strong selective α‐nucleating agent, thus it has a great influence on the course of crystallization and on the polymorphic composition. Even at a low concentration (C ≥ 1%), talc suppresses the formation of the β‐modification. In its presence, only products of high proportion of β‐modification can be prepared.Mechanical characteristics of the composites were determined.
Studies on hydride terminated methylhydro‐dimethylsiloxane copolymers
Authors: Joseph M. A. , Haque S. A. , Grover S. S. , Francis D. J. 
Published: April 2003

AbstractSynthesis of hydride terminated methylhydro‐dimethylsiloxane copolymers from the hydrolyzates of 10, 20, 30, 50 and 70% vol.‐% dichloromethylsilane with dichlorodimethylsilane have been carried out. The copolymers were characterized by IR‐and 1H‐NMR‐spectroscopy and standard chemical analysis. They were used as curatives for a standard vinyl functional room temperature vulcanizing (RTV) silicone material based on addition cure, and the vulcanizate properties have been evaluated. The copolymers with high hydride content gave better mechanical properties and thermal stability to the vulcanizates.
Thermal behaviour of TiO2‐encapsulating polymers
Authors: Haga Yutaka , Watanabe Takanobu , Yosomiya Ryutoku , Isizawa Ryosyo 
Published: April 2003

AbstractComparing the thermal properties of TiO2 encapsulating polystyrene and poly(methyl methacrylate) with those of TiO2 dispersion polymers it was found that the encapsulating polymers have two thermal relaxation regions. The activation energy of those thermal relaxation regions was determined using the Wunderlich method and it was found that the values are similar to the activation energy for the dynamic dispersion. It is suggested that the low‐temperature thermal relaxation is caused by the local change of conformation of molecular chains, while the high‐temperature thermal relaxation is similar to that of the normal glass transition temperature including the interaction with TiO2. In addition, the thermal behaviour near the degradation point in different atmospheres indicates that the encapsulating polymer has a specific structure for adsorbing a large amount of oxygen.
Photooxidation of polyacetal copolymers, 1. A preliminary study of the long wavelengths photooxidation
Authors: Gardette Jean‐Luc , Sabel Hans‐Dieter , Lemaire Jacques 
Published: April 2003

AbstractPhotooxidation of three polyacetals is described. These copolymers present different structures, but it is shown that the presence of CC bonds vicinal to oxygen or the presence of tertiary carbon do not control their photoreactivity. The final photoproducts were identified by chemical treatments associated to IR spectroscopy. A mechanism involving primary hydroperoxides is proposed, which leads to the formation of carbonates, formates, and hydroxylated compounds.
Etude du vieillissement d'un assemblage métal/adhésif/métal par impédancemétrie électrique et viscoélasticimétrie
Authors: Bourahla Hamid , Lenoir Jeanine , Chauchard Jacques , Romand Maurice 
Published: April 2003

AbstractL'évolution des caractéristiques électriques d'un assemblage collé acier inoxydable/adhésif en film/acier inoxydable est étudiée en fonction du temps de vieillissement en atmosphère chaude et humide. A partir de mesures non destructives d'impédance électrique, il est montré que l'absorption d'eau par le joint conduit à une diminution de sa résistance en basse fréquence et à un accroissement de sa constante diélectrique. La sorption d'eau dans le joint résulte de deux processus simultanés:— La fixation de molécules d'eau sur les sites polaires de l'adhésif. Ce phénomène est caractérisé par une dispersion électrique croissante en basse fréquence.— La migration d'eau libre dans des microcavités. Ce phénomène entraîne un accroissement de la permittivité en haute fréquence.La proportion relative de ces deux phases (eau structurale et eau libre) est également donnée.D'autre part, ce travail montre que la nature du traitement de surface du métal provoque une modification de la cinétique de sorption d'eau.Ces résultats sont en accord avec ceux obtenus par analyse thermomécanique dynamique.
Aliphatisch‐aromatische polyethersulfone, II. Polykondensationsprodukte aus bis‐(4‐hydroxyphenyl)‐sulfon und bis‐(4‐chlormethylphenyl)‐verbindungen—synthese und struktur
Authors: Podkościelny Wawrzyniec , Dethloff Jadwiga , Dethloff Michael , Brunn Joachim 
Published: April 2003

AbstractDurch Polykondensationsreaktionen von Bis‐(4‐hydroxyphenyl)‐sulfon mit Bis‐(4‐chlormethylphenyl)‐verbindungen der allgemeinen Formel (ClCH2Ar)2X, wobei X eine Einfachbindung oder eines der zweiwertigen BrückengliederCH2,CO,O,S oderSO2bedeutet, wurden neue aliphatisch‐aromatische Polyethersulfone erhalten.Die Reaktionen wurden in hochsiedenden polaren Lösungsmitteln bei Anwendung äquimolarer Mengen an Substraten und eines 15proz. molaren Überschuses von Kaliumcarbonat als HCl‐Akzeptor unter einer Stickstoffatmosphäre durchgeführt.Die verwendeten Bis‐(4‐chlormethylphenyl)‐verbindungen unterscheiden sich hinsichtlich ihrer Reaktivität. Für die gesamte untersuchte Monomerreihe wurden die folgenden günstigsten Reaktionsbedingungen ermittelt:Lösungsmittel N,N′‐Dimethylacetamid, Reaktionstemperatur 120°C, Reaktionszeit 30 min, Konzentration der Lösung 0,8 mol/l.Die erhaltenen Polykondensate besitzen ein mittleres Molekulargewicht M̄w von 10000–50000. Sie sind linear nach dem Typ A‐B‐A‐B aufgebaut.
Aliphatisch‐aromatische polyethersulfone, III. Eigenschaften der polykondensationsprodukte aus bis‐(4‐hydroxyphenyl)‐sulfon und bis‐(4‐chlormethylphenyl)‐verbindungen
Authors: Podkościelny Wawrzyniec , Dethloff Jadwiga , Dethloff Michael 
Published: April 2003

AbstractDie thermischen, mechanischen und dielektrischen Eigenschaften von aliphatischaromatischen Polyethersulfonen, die durch Polykondensation von Bis‐(4‐hydroxyphenyl)‐sulfon mit Bis‐(4‐chlormethylphenyl)‐Verbindungen der allgemeinen Formel (ClCH2Ar)2X (X steht für eine Einfachbindung oder eines der zweiwertigen BrückengliederCH2,O,CO,SoderSO2) erhalten wurden, werden beschrieben. Die Polykondensate besitzen Glasumwandlungstemperaturen von über 145°C. Die Zersetzung der amorphen Polykondensate wird erst oberhalb 300°C beobachtet. Die Löslichkeit der aliphatisch‐aromatischen Polyethersulfone in verschiedenen organischen Lösungsmitteln wurde untersucht. Die mechanischen Eigenschaften von Preßlingen wurden bei Raumtemperatur und die dielektrischen in Abhängigkeit von der Temperatur und Frequenz bestimmt.Ihrem Sauerstoff‐Index nach können diese Polyethersulfone zur Gruppe selbstverlöschender Kunststoffe gezählt werden.
Synthese und charakterisierung von telechelen oligosiloxanen
Authors: Klemm Elisabeth , Beil Ulrike 
Published: April 2003

AbstractPhotopolyaddition von 1,8‐Dimercaptooctan an 1,1,3,3‐Tetramethyl‐1,3‐divinylsiloxan führt zu SH‐ oder vinylterminierten Telechelen. DC und HPLC‐Untersuchungen zeigen, daß die Telechelen Mischungen von Oligomeren mit wachsender Kettenlänge sind, deren Verteilung nur vom Molverhältnis r der Monomeren abhängt. Die Antimarkownikow‐Struktur ist durch NMR‐Analyse belegt.
Copolymerization of tri‐n‐butyltin‐α‐chloroacrylate with 2‐hydroxyalkyl methacrylates
Authors: Joshi Ravi R. , Gupta Sudhir K. , Dharia Jayesh R. 
Published: April 2003

AbstractCopolymers of tri‐n‐butyltin‐α‐chloroacrylate (TCA) with 2‐hydroxyethyl methacrylate (HEMA) and 2‐hydroxypropyl methacrylate (HPMA) were synthesized in solution at 55°C using azobisisobutyronitrile as initiator. Copolymer compositions were determined by tin analysis. Monomer reactivity ratios were calculated by the Kelen‐Tüdős method. The copolymers were further characterized by IR, 1H‐NMR, TGA, DSC, XRD and solubility. Biotoxicity studies of the copolymers are also reported. The copolymer system is compared with similar copolymers of tri‐n‐butyltín methacrylate.