bluuebunny/crossref_metadata_2025 huggingface dataset:
Separation of liquid mixtures by using polymer membranes. II. Water‐alcohol separation by pervaporation through porous PVA membranes
Authors: Hu Chun‐Min , Chiang Wen‐Yen
Published: April 2003

The permeation and separation characteristics of alcohol/water systems through porous PVA membranes were investigated. Porous PVA membranes with different pore size and number were prepared by solution blending of PVA with several synthesized polymers or copolymers, such as polyacrylic acid, polyacrylamide, polyacrylonitrile, and methylmethacrylate‐co‐maleic anhydride, etc. Then casting, and finally extracting the blended polymers or copolymers by solvent from the membranes. The dependency of both permeation and separation on the molecular size and shape of the permeating species was dicussed qualitatively. Moreover, the permselectivity was investigated with attention to the feed composition of alcohol/water mixture and the effect of pore size and number. The selectivity was found to depend on the weight ratio and the molecular weight of polymer introduced to the membrane. When the weight ratio of polymer introduced into the membrane was larger than 0.1, methanol was permeated through membrane preferentially in methanol/water system, and the separation factor increased with increasing the methanol feed concentration. On the other hand, membrane had a selective permeability for water in the other alcohol/water systems. The influence of operating conditions was also studied.
Study of ternary component intermacromolecular complex formation involving Ni(II), phenolic copolymer and acrylic copolymer
Authors: Chatterjee S. K. , Ghosh Sudipta , Yadav D. , Farahani B. V.
Published: April 2003

Two phenolic copolymers and a methacrylic acid‐methacrylamide copolymer have been synthesized and characterized by known methods. The respective comonomer units of the copolymers enter into complex formation through hydrogen bonding and ion‐dipole interactions. The interaction of the intercopolymer complex with a typical transition metal ion (e. g., Ni(II)) has been studied by several experimental techniques, e. g. viscometry, potentiometry, conductometry, IR, and UV spectrophotometry. Formation of metal‐intercopolymer complexes of distinct stoichiometries have been predicted, and some schemes have been suggested to explain the mode of interaction between the components.
The properties of polymer blends of the β‐modification of polypropylene and an elastomer
Authors: Varga József , Garzó Gábor
Published: April 2003

Blends of β‐polypropylene with elastomers have been prepared under laboratory and processing technological conditions. As a result of the elastomer addition the temperature interval favourable for the formation of the β‐modification became narrower. Blends have spherulitic structure like pure β‐PP. The elastomer has negligible effects on the size of spherulites and on the rate of crystallization. Optical microscopy and DMA measurements revealed that the blends were two‐phase systems in the solid state.

The mechanical properties of the blends are close to those of β‐PP in the investigated composition range. Increasing elastomer content reduced the strength characteristics but considerably improved cold impact resistance, the most beneficial combination containing about 8–12% of elastomer. A mathematical relationship has been proposed describing the relationship between impact strength and elastomer content. The dependence of the structural characteristics and macroscopic properties of elastomer‐modified β‐PP blends on the composition and on the temperature is similar to that of the identical β‐PP blends.
Anwendung diskreter diffusions‐adsorptions‐modelle auf das färben von polyacrylnitrilfasern mit kationischen farbstoffen
Authors: Engelmann Uwe , Schmidt‐Naake Gudrun , Pippel Winfried , Flath Hans‐Joachim
Published: April 2003

Auf der Grundlage eines Zellenmodells der Faser mit transienten und adsorbierenden Zuständen wurden ein Diffusions‐Adsorptions‐Modell mit nach jedem Zeitschritt eingestelltem Adsorptionsgleichgewicht sowie ein Färbeprozeßmodell mit zeitabhängigem Diffusions‐ und Adsorptionsprozeß abgeleitet. Für das Färben einer Polyacrylnitrilfaser mit 6 verschiedenen kationischen Farbstoffen bei 93°C und 98°C erfolgte die Bestimmung der Modellparameter — Diffusionskoeffizienten und kinetische Konstanten von Ad‐ und Desorption — durch Anpassung an experimentelle Aufziehkurven unter Verwendung der Parameter der Adsorptionsisotherme nach Langmuir. Die erhaltenen Diffusionskoeffizienten liegen in der Größenordnung von 10−9 cm2/s. Der geringe Unterschied der Ergebnisse der beiden unterschiedlichen verwendeten Färbemodelle stützt die Annahme, daß die Diffusion den geschwindigkeitsbestimmenden Schritt darstellt. Beim Färben mit Crypurrot GTL bei 93°C zeigte sich jedoch, daß die Adsorptionsgeschwindigkeit nicht in jedem Fall vernachlässigt werden kann.
Thermische und mechanische eigenschaften von polyurethanen mit mesogenen diolkomponenten
Authors: Lorenz R. , Els M. , Haulena F. , Schmitz A. , Lorenz O.
Published: April 2003

Es wurden thermische und mechanische Eigenschaften von nichtsegmentierten und segmentierten Polyurethanen untersucht, die als Diolkomponente 4,4′‐Di(ω‐hydroxyalkoxy)biphenyle mit unterschiedlicher Spacerlänge enthalten. DSC‐Messungen zeigten, daß die bei den nichtsegmentierten Polyurethanen auftretenden thermischen Übergänge auch bei den segmentierten beobachtet wurden, allerdings unter Verschiebung zu tieferen Temperaturen. Polarisationsmikroskopische Untersuchungen an den nichtsegmentierten Polyurethanen weisen auf das Vorliegen von LC‐Phasen hin.

Die Spannungswerte von Filmen segmentierter Polyurethane nahmen mit steigender Spacerlänge insbesondere bei Temperaturen ≤40°C zu. Dies wird auf eine mit steigender Spacerlänge erfolgende Entkopplung der Bewegungen von mesogenem Bereich und Urethanteil zurückgeführt. Die Entkopplung fördert gleichzeitig die Bildung größerer Domänen des Mesogens. Oberhalb eines temperaturabhängigen kritischen Spannungswertes treten Fließvorgänge auf.

Eine chemische Vernetzung unterhalb der thermischen Übergänge führt zu einer Verbesserung der mechanischen Filmeigenschaften, da sich die durch Domänen des Mesogens bewirkte physikalische Vernetzung der chemischen überlagert. Die Untersuchung erfolgte an einem Polyurethan mit COOH‐Gruppen, das bei Temperaturen unterhalb bzw. oberhalb der thermischen Übergänge mit einem Melaminharz vernetzt wurde.
Molar mass distribution determination of natural rubber and masticated natural rubber by gel permeation chromatography
Authors: Bartels Holger , Hallensleben Manfred L. , Pampus Gottfried , Scholz Günter
Published: April 2003

A procedure for analyzing natural rubber via gel permeation chromatography without separating any gel was elaborated. Natural rubber and masticated natural rubber were studied by Mooney‐viscosity, solution viscosimetry and gel permeation chromatography. We show that the determination of the molecular mass distribution can easily and quickly be done by this method and it is urgently needed for the inquiry into the mechanisms of mastication and as a method of quality control of natural rubber in rubber industry.
A staining procedure for the detection of oxidized sites in polyolefins
Authors: da Costa Ricardo Aurélio , Coltro Leda , Galembeck Fernando
Published: April 2003

Oxidized areas in polyolefin (PE, PP, EPDM) solids can be located by immersion in a warm isopropanolic solution of Sudan III and methylene blue, followed by observation of the solid discoloration pattern. Oxidized sites are stained blue, nonoxidized sites are stained pink. UV/Vis transmission and photoacoustic spectra can be obtained from the stained samples.
Oberflächenstrukturierung polymerer fasern durch UV‐laserbestrahlung. 8. Schwellenverhalten der laserinduzierten oberfläauchenstrukturierung von poly(ethylenterephthalat)
Authors: Kesting W. , Bahners T. , Knittel D. , Schollmeyer E.
Published: April 2003

Bei UV‐Excimer‐Laserbestrahlung von biaxial verstreckten Poly(ethylenterephthalat) (PETP)‐Folien durch einen Spalt oder durch kreisförmige Blenden entstehen unter geeigneten Bestrahlungsbedingungen die bekannten charakteristischen Strukturierungen, welche durch Fresnelsche Beugungserscheinungen modifiziert sind. Die Beugung des Laserlichtes führt zu lokalen Intensitätsunterschieden auf der PETP‐Oberfläche. Unter Ausnutzung dieses Beugungseffektes wurde eine higher nicht gemessene Grenzenergie für die laserinduzierte Ausbildung der Oberflächenmorphologie von PETP bestimmt. Wesentlich ist hierbei, daß diese Strukturschwellenenergie deutlich unterhalb der extrapolierten Ablationsschwellenenergie von PETP liegt. Darüber hinaus wird an Elastomerfasern aufgezeigt, daß die Grenzenergie zur Strukturbildung auch von der Größe eines extern aufgebrachten Spannungsfeldes abhängt.
Synthesis of pyrrones based on the reduction and cyclization of their o‐nitrosubstituted polyimides precursors
Authors: Sideridou‐Karayannidou Irini , Karayannidis Giorgos
Published: April 2003

Pyrrones derived from 1,2,4,5‐tetraaminobenzene and pyromellitic dianhydride or 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride were prepared by catalytic reduction and cyclization of the poly(o‐nitro)imides, obtained by polycondensation of 1,3‐dichloro‐4,6‐dinitrobenzene with the dipotassium salt of pyromellitic diimide or 3,3′,4,4′‐benzophenonetetracarboxylic diimide. These polymers were characterized by slightly better thermal stability as compared with the polymers of the same structure obtained by conventional methods. The model compound for these polymers has been also synthesized by catalytic reduction and cyclization of 1,3‐bis(phthalimido)‐4,6‐dinitrobenzene.
Separation of iridium from platinum using a modified glycidyl methacrylate copolymer with diethylamino groups
Authors: Kálalová E. , Thuy Pham
Published: April 2003

A macroporous glycidyl methacrylate — ethylene dimethacrylate copolymer with sorption‐active diethylamino groups proved to suit well for the separation of two component mixtures of chloro complexes [lrCl6]2‐ and [PtCl6]2‐. A method for the separation was worked out, based on the reduction of the two complex ions with an aqueous solution of SO2, after which iridium(III) is easy to elute (1 M HCI) where as platinum(II) is only eluted with 5 M HCI. The reaction patterns are given, supported by spectroscopic evidence.
Wettability and surface chemistry of irradiated PTFE
Authors: Morra A. , Occhiello E. , Garbassi F.
Published: April 2003

Low energy electron irradiation of PTFE induced fluorine depletion and introduction of oxygen on the surface. The effect on surface chemistry was shown to be dependent mostly on the amount of electrons reaching the sample, rather than on their energy.

Changes in surface energy resulted in different wetting behaviors. The measurement of advancing water contact angles and the analysis of XPS C‐1s peak shapes showed that the least wettable portion of irradiated surfaces is made in most cases of CF2CF  units. When the treatment caused a nearly complete fluorine depletion, only isolated CF2 or CF groups are present. Receding angle values decreased linearly depending on the amount of oxygen introduced on the sample during the treatment, suggesting the formation of strongly oxidized polymer islets. The invariance of contact angles with aging time indicated very low macromolecular mobility, probably related to extensive surface crosslinking.
Neue polymer‐additive, 1. Füllstoffe auf basis von modifizierten siliciumdioxiden
Authors: Bräuer Leopold , Gruber Heinrich , Greber Gerd
Published: April 2003

Durch Umsetzung von Siliciumdioxiden (SD) mit Methyldichlorsilan wurden HSi‐modifizierte SD (I) erhalten, aus denen durch Hydrosilylierungsreaktionen mit geeigneten CC‐ungesättigten Partnern neuartige (Reaktiv‐)Füllstoffe mit bspw. Harnstoff‐ oder Melamin‐Resten zugänglich sind, die methylolierbar und daher kovalent in Formaldehyd‐Harze einkondensierbar sind. Die Addition von I an Divinylbenzol (DVB) führte zu Styrol‐modifizierten SD VII, die mit beliebigen ungesättigten Monomeren copolymerisierbar sind. Die resultierenden SD‐Pfropfcopolymeren zeigten in Abhängigkeit vom verwendeten Monomeren entweder hydrophile (Acrylnitril) oder stark hydrophobe (Styrol, Acrylsäuremethylester) Eigenschaften, im letzteren Fall gute Verträglichkeit mit organischen Medien.
New resin system for low‐pressure moulding compounds with special properties
Authors: Hacker H. , Hauschildt K. , Huber J. , Laupenmühlen H. , Wilhelm D.
Published: April 2003

Moulded materials produced from aromatic epoxide resins, aromatic polyamines with high‐temperature‐resistant structure units and powdered mineral fillers possess outstanding properties like high glass transition temperatures, high mechanical strength, low linear thermal expansion coefficient, and reduced flammability without the addition of flame retardants. An account is given of the synthesis of aromatic polyamines, the preparation and working of moulding materials and the properties of the finished products.
Synthesis, characterization and kinetics of thermal decomposition of various peroxycarbamates and their initiation of methyl methacrylate polymerization
Authors: Yildirim Hüseyin , Baysal Bahattin M.
Published: April 2003

Several dimeric and polymeric peroxycarbamates were synthesized using various aliphatic diisocyanates and hydroperoxides. The products were characterized by IR spectroscopy, molecular weight measurements, isocyanate and peroxide analyses. Thermal decomposition kinetics of these peroxycarbamates were studied in 1,4‐dioxane or toluene solutions at 80, 90, and 100°C. All reactions were found to proceed according to a first‐order kinetics with activation energies in the range of 126–144 kJ/mol, depending on the structure of the peroxycarbamate. One of the polymeric products was used to initiate methyl methacrylate polymerization at 80°C in bulk. The initiating activity of this peroxycarbamate was found to be better than that of some hydroperoxides.
Interactions of some liquid chemicals with polyolefins
Authors: Iring Margit , Barabás Klára , Földes Enikő , Tüdős Ferenc , Ódor Lujza
Published: April 2003

Polyolefins are known to be highly resistant towards chemicals. It is shown, however, that both chemical and physical interactions take place between them which lead to changes in the initial advantageous properties. The interactions are rather slight in the case of HCl and NH4OH solutions. At the same time several limitations must be considered in the storage of high purity organic liquid chemicals. Apart from electronic grade, however, the organic reagents used in this study except from Freon TF may be stored in vessels made of polyolefins.
An investigation of poly(tetrafluoroethylene) surfaces after etching with anion radicals by means of XPS photoelectron spectroscopy
Authors: Lukáš J. , Lochmann L. , Kálal J.
Published: April 2003

The layer of reaction products on the surface of poly(tetrafluoroethylene) etched with a solution of sodiumnaphthalene in tetrahydrofuran was investigated by means of XPS photoelectron spectroscopy. The etched surfaces were also examined after vigorous rinsing with water and tetrahydrofuran. Using the elementary compositions thus determined and chemical shifts in XPS spectra, information was obtained regarding the concentration gradient of the elements and the chemical composition at various depths of the etched layer.
Synthesis and properties of a new o‐cresol novolak epoxy resin containing oxyethylene units
Authors: Iijima Takao , Kabaya Hidekazu , Tomoi Masao
Published: April 2003

A new o‐cresol novolak epoxy resin containing oxyethylene units was synthesized and characterized. The mechanical, thermal, and dynamic mechanical properties of resins cured with methyl hexahydrophthalic anhydride were examined and compared to those of a conventional o‐cresol novolak epoxy resin (EOCN 1020). This new epoxy resin gives a cured resin with higher flexibility, compared to the conventional one.
Graft copolymerization of methyl methacrylate onto modified plantain pulp in the presence of ceric ions
Authors: Okieimen Felix E. , Uroghide Isaiah N.
Published: April 2003

Plantain pulp was modified by treatment with allyl chloride in diisopropyl ether at 60 °C which results in an average degree of substitution of 0.215 allyl chloride moieties per anhydroglucose unit (AGU). Graft copolymerization of methyl methacrylate onto modified and unmodified pulp was carried out at 29 °C using various concentrations of ceric ion initiator. It was found from the dependence of the extent of graft polymer formation on ceric ion concentration that termination of graft polymerization occurred mainly by the interaction of growing graft polymer chains with ceric ion and that the extent of graft polymer formation was markedly enhanced by the modification of the plantain pulp. The effect of isopropanol on the extent of graft polymer formation on the modified material was also examined.
Photooxidation of polyethylene films, 1. Experimental kinetics of functional group formation
Authors: Gugumus F.
Published: April 2003

The variation of the photooxidation of PE‐LD films as a function of film thickness depends heavily on the exposure device used for artificial weathering. Carbonyl development is practically proportional to film thickness if high UV intensity artificial exposure devices are used. With less accelerating devices and on outdoor exposure, only limited increase with film thickness is observed. Then, an appreciable part of total oxidation is restricted to the surface layers. The differences between exposure devices are attributed to the absence of chain reactions in polyethylene with high UV intensity devices. With other accelerating devices and on outdoor exposure, chain reactions occur especially in the surface layers of the films where they involve usually oxidation products.
Photooxidation of polyethylene films, 2. Mechanisms and kinetics of functional group formation
Authors: Gugumus F.
Published: April 2003

Various mechanisms are proposed to explain the formation of the photooxidation products of the PE‐LD films (ketones, carboxylic acids, vinyl groups). The kinetics of product formation are discussed in detail. The experimental results can be explained on the assumption that the rate of ketone formation increases linearly with exposure time. Possible explanations are proposed.
Models for photoinduced processes in polymeric materials
Authors: Blumen Alexander , Roy Apurba Kumar , Schnöurer Horst
Published: April 2003

The article focusses on energy transfer experiments and on photoconductivity measurements in polymeric materials. The results are interpreted in terms of scaling theories; fractals are used to describe the spatial and continuous‐time random walks (CTRW) the temporal disorder. We display some successful applications of scaling ideas and also draw attention to the limitations of the models.
Photosensibilisierte radikalische Polymerisation
Authors: Braun Dietrich
Published: April 2003

After a short survey on the various types of light‐induced free radical polymerisations the most important applications of such reactions are summarized. In some detail is reported on the use of aza‐aromatic compounds as photo‐sensitizers and their initiation mechanism is discussed.
Lichtinduzierte Umorientierung der optischen Achse in LC‐Farbstoff‐Copolymeren
Authors: Endres Bernhard , Krieg Manfred , Omeis Jürgen , Rau Norbert
Published: April 2003

Untersucht wird der Einfluß von linear und zirkular polarisiertem Licht auf den Ordnungszustand von nematischen Farbstoff‐ Copolymeren. Am Beispiel eines Modellsystems wird gezeigt, daß mit linear polarisiertem Licht die optische Vorzugsachse dieser Systeme gezielt reorientiert werden kann. Die Untersuchungen zeigen, daß der Isomerisierungszyklus des Azofarbstoffes für diese Eigenschaft des Materials verantwortlich ist Nach Bestrahlen der Probe mit zirkular polarisiertem Licht wird für das Polymere das gleiche Transmissionsverhalten beobachtet. Wie es auch selektivreflektierende Materialien, z. B. cholesterische Flüssigkristalle, aufweisen.
Spectral holes as probes for structural transitions in polymers
Authors: Friedrich J.
Published: April 2003

We show how narrow spectral holes burnt into the inhomogeneous absorption of dye doped polymers can be used as extremely sensitive detectors for measuring structural rearrangement processes. A model is suggested which relates the observed hole burning phenomena to the specific heat of the conformation phase space.
HERSTELLUNG VON MIKROSTRUKTURPRODUKTEN DURCH TIEFENLITHOGRAFIE UND SPRITZGUSS
Authors: Götz F. , Ehrfeld W.
Published: April 2003

For fabricating microstructures with extreme structural heights a technology has been developed which is based on deep‐etch lithography and subsequent replication processes. A particularly high precision is achieved if the lithographic process is carried out by means of synchrotron radiation. Electroforming and molding processes are used for the replication of microstructures from a large variety of materials. The field of application comprises micromechanics, microoptics, electrical and optical microconnectors as well as sensors and actuators.
OPTISCHE UND ELEKTRO‐OPTISCHB SCHALTPROZESSB IN POLYMEREN FLÜSSIGKRISTALLEN
Authors: Birenheide R. , Wendorff J. H.
Published: April 2003

Low molar mass and polymeric liquid crystals display extremely large electro‐optical and nonlinear optical responses, due to a combination of orientational long range order and fluidity. These responses are controlled on the one hand by the intrinsic anisotropic dielectric and optical properties of these phases and on the other hand by their peculiar curvature elastic and viscous properties.

Polymeric liquid crystals, although having the disadvantage of longer response times, offer the advantage that the liquid crystalline state and any modulation imposed on it can be frozen in a glassy state. Polymeric liquid crystals can thus be used in various applications related to the control of light propagation, optical information storage and the manufacturing of holographic optical elements.
Blends of bismaleimide resins and bis(allyl phenyl) esters
Authors: Varma I. K. , Gupta S. P. , Varma D. S.
Published: April 2003

The effect of reactive diluents such as bis(4‐allyl 2‐methoxyphenyl) adipate (AEg), bis(4‐allyl 2‐methoxyphenyl) terephthalate (TEg), and bis(o‐allyl phenyl) sebacate (APS) on curing characteristics and thermal behaviour of bis(4‐maleimidophenyl) methane (BM) chain‐extended with 4,4′‐diaminodiphenyl methane (DADPM) is described. Samples containing 5, 10, 15, 20, 25, 35, and 45 wt.‐% of these reactive diluents and bismaleimide resin were prepared. Addition of APS, AEg, and TEg affected the curing exotherm of bismaleimides. The thermal stability of bismaleimide decreased on addition of APS or AEg, but in presence of TEg an improvement in char yield at 800°C was observed. Glass fibre reinforced laminates fabricated from bismaleimide resin containing 10% APS exhibited interlaminar shear strength of 20.8 N/mm2 and flexural strength of 541 N/mm2.
Composites of furfuryl alcohol‐formaldehyde resins and olive stones for production of activated carbons
Authors: Simitzis Johannis
Published: April 2003

Composites based on resin of furfuryl alcohol‐formaldehyde or poly(furfuryl alcohol) and olive stones (pressed and extracted as received from industrial production) were cured as small cylinders and then pyrolyzed. The pyrolysis was studied by thermogravimetric analysis up to ∼︁ 1000°C and by FTIR‐spectroscopy for the initial composites and their pyrolysis residues up to 500°C. The specific surface areas of the carbonaceous residues and their discoloring ability for dyes of methylene blue and alizarin yellow were determined. The results are interpreted and discussed under the aspects of the pyrolysis process and the new carbonaceous materials produced. The usage of olive stones in mixture with resins based on furfuryl alcohol is more advantageous (e. g. leading to higher adsorption of the dyes) than the usage of the resin alone.
Application de l'impédancemétrie électrique à l'étude de la réticulation d'un adhésif en film. Cas d'un assemblage métal/métal
Authors: Bourahla Hamid , Lenoir Jeanine , Romand Maurice
Published: April 2003

Sous l'action d'un traitement thermique, la réticulation d'un adhésif en film s'accompagne d'une variation des propriétés rhéologiques et électriques de la résine. L'intérêt des mesures non destructives d'impédance électrique est de permettre de suivre en continu la réticulation, de déterminer en particulier le début et la fin du mouillage, le point de gélification et la fin de la réticulation du film d'adhésif (FM 96) utilisé en vue d'élaborer un joint collé métal/métal (acier inoxydable 22 CN 18‐10). L'influence de la température et de la durée de réticulation est également mise en évidence. Aprés un second balayage en température, les diagrammes d'impédance sont caractéristiques de l'existence d'un reéiculat polyphasé. Ces résultats sont confirmés par analyse thermique (DSC et DTMA).
Charakterisierung von vernetzten polymeren mittels verdampfungsanalyse, 8. Feinporige adsorberpolymere auf polystyrolbasis
Authors: Häusler Karl‐Georg , Bischof Gert Jürgen , Popov Georgi , Feistel Lothar , Schwachula Gerhard
Published: April 2003

Ergebnisse aus Verdampfungsanalyse und Quecksilberporosimetrie zeigen bei feinporigen Adsorberpolymeren auf Polystyrolbasis des Typs Wofatit Y 77 signifikante Unterschiede des Porenvolumens. Der Vergleich der beiden Werte ermöglicht die Bestimmung des Beitrages der Mikroporen zum Gesamtporenvolumen. Darüber hinaus ermöglicht diese einfache Methode die Bestimmung des Quellungsgrades der Polymermatrix.
Copolymerization of alkyl α‐chloroacrylates with methyl methacrylate
Authors: Pathak C. P.
Published: April 2003

Hexyl α‐chloroacrylate (HCA) and cyclohexyl α‐chloroacrylate (CCA) have been copolymerized with methyl methacrylate (MMA) in toluene at 55°C using azobisisobutyronitrile (AIBN) as initiator. Copolymer compositions have been determined both by 1H NMR and elemental analyses. For copolymerization of MMA (M1) with HCA (M2), the reactivity ratios (RR) are r1 = 0.47 ± 0.19 and r2 = 0.81 ± 0.51 and with CCA the values are r1 = 0.76 ± 0.31 and r2 = 2.30 ± 1.73. Thermal properties of these copolymers have also been investigated.
Effects of processing variables on the mechanical properties of compression molded polystyrene‐wood fiber composites
Authors: Sean Sy Trek , Sanschagrin Bernard , Kokta Bohuslav V. , Maldas Debesh
Published: April 2003

Optimization of mixing and molding conditions (e.g. temperature, time and pressure) of aspen chemithermomechanical pulp (CTMP)‐polystyrene composites was carried out. Compounding conditions showed a substantial effect on the mechanical properties of the composites. The effect of fiber encapsulation with polystyrene on the mechanical properties of the composites was also evaluated. Compared to non‐encapsulated ones, the mechanical properties of composites showed superior results when encapsulated CTMP fibers were used. After encapsulation of wood fibers, and optimization of mixing and molding conditions, composites with up to 36% of fiber volume fraction could be incorporated in polystyrene with improved mechanical properties.
Charakterisierung der stabilität von modifizierten polypropylen‐glasfaser‐verbunden nach thermo‐ und photooxidation
Authors: Peter Ralf , Mäder Edith , Rätzsch Manfred , Kovářova Jana , Rotschová Jitka , Pospíšil Jan
Published: April 2003

Homopolymerisat und verschieden chemisch modifiziertes Polypropylen wurden für die Compoundierung mit Glasfasern unter Anwendung verschiedener Stabilisierungsvarianten im Hinblick auf ihre thermo‐ und photooxidative Beständigkeit charakterisiert. Zur Untersuchung der thermooxidativen Stabilität der Polymer‐Compounds wurde die direkte Messung der Sauerstoffabsorption angewendet. Die durch die thermischen Oxidationsprozesse hervorgerufenen Veränderungen in der Zähigkeit und im Dehnungsverhalten wurden durch den Schlagbiege‐ und den Zugversuch charakterisiert. Die durch die Photoalterung hervorgerufenen Veränderungen wurden IR‐spektroskopisch verfolgt. Die Untersuchungsergebnisse werden hinsichtlich des Einflusses von Stabilisatorsystem, Modifikator und Glasfasern diskutiert.

Demnach weisen die mit 0,10% BHT, 0,30% DSTP, 0,05% Irganox 1010 und 0,25% Tinuvin 770 stabilisierten Compounds im Ausgangszustand und nach kurzen Alterungszeiten die beste thermooxidative und mechanische Beständigkeit auf. Dieser Effekt verliert sich mit zunehmender Alterungsdauer. Bezüglich des Modifikators zeigen die mit einem Gemisch aus Acrylsäure und Maleinsäureanhydrid im Verhältnis 5:1 modifizierten Proben thermooxidativ und mechanisch das beste Verhalten, photooxidativ dagegen das schlechteste. Reiner Maleinsäureanhydrid‐Modifikator führt zu einer deutlichen Verschlechterung des thermooxidativen und mechanischen Verhaltens, die UV‐Beständigkeit wird im Vergleich zu unmodifizierten Proben nicht beeinflußt. Die Glasfasern bewirken eine deutliche Verbesserung der Verbundeigenschaften — vor allem bei Einsatz eines Modifikators —, eine signifikante Retardierung des Thermooxidationsverlaufes sowie eine Erniedrigung der Photostabilität, wobei der letztere Einfluß nicht eindeutig ist.
Heterogeneous functionalizing of polysulfone membranes
Authors: Breitbach Ludger , Hinke Ekkehard , Staude Eberhard
Published: April 2003

In recent years efforts have been increased to work with more intelligent membranes which render more than normal filtration properties. Thus, membranes have been prepared using chemically modified polymers or have been furnished with additives in order to increase their selectivity and/or special sorbing capabilities. In this paper, methods are described how commercially available polysulfone membranes can be functionalized by chemical reactions without disintegrating their mechanical properties. For this purpose, Sulfonation, chloromethylation, aminomethylation, and lithiation reactions were applied. A broad spectrum for further conversions modified membranes is opened by these chemical reactions which allow an individual fitting of the membranes with special substitutes. The chemical reactions and the analytical procedures are also described.
A DSC investigation on the stabilizer distribution in PVC blends
Authors: Braun Dietrich , Eidam Norbert , Kömmerling Stefan
Published: April 2003

The distribution of a liquid organotin stabilizer between the phases of heterogeneous poly(vinyl chloride) (PVC) blends has been studied by differential scanning calorimetry (DSC). This method can be used even at low stabilizer concentrations. At concentrations > 1 wt.‐% the stabilizer can be detected in both phases of a PVC/SAN (poly(vinyl chloride)/poly(styrene‐co‐acrylonitrile)) blend. At lower concentrations no stabilizer could be found in the SAN phase. Determination of the induction period of thermal degradation at 180°C under nitrogen atmosphere showed no loss of thermal stability for blends containing the stabilizer partly in the SAN phase. Kinetic measurements with the DSC indicate a migration of the stabilizer out of the SAN phase, PVC/PMA (poly(vinyl chloride)/poly(methyl acrylate)) blends showed no solubility of the stabilizer in the soft PMA phase.
Durch Matrixmodifizierung und Zusatzstoffe zu Polyesterverbunden mit speziellen Eigenschaften
Authors: Bledzki Andrzej K. , Jakobi Rolf
Published: April 2003

Ungesättigte Polyester ergeben durch Modifizierung der Harzkomponente oder durch Additive Werkstoffe mit einem breiten Eigenschaftsprofil. Die mechanischen Werte sind durch chemische Modifikation der Polymerkette oder durch kautschukartige Additive gezielt einstellbar. Antistatische Eigenschaften und elektrische Leitfahigkeit lassen sich durch Zugabe von Rußen, Graphit oder metallischen Füllstoffen erreichen. Gleichzeitig kann auch die Wärmeleitfähigkeit beeinflußt werden. Andere Füllstoffe verbessern das Reibungs‐ und Verschleißverhalten oder können bei Zugabe von Mikrohohlkugeln zu deutlicher Gewichtsverminderung führen. Die gezielte Veränderung der Eigenschaften trägt wesentlich zum Einhalten erhöhter Sicherheitsanforderungen bei.
NEUE VERARBEITUNGSMETHODEN FÜR RIESELFÄHIGE DUROPLASTE
Authors: Braun U.
Published: April 2003

Duroplastische Formmassen werden nach konventionellen Verfahren der Kunststofformgebung wie Formpressen und Spritzgießen bzw. deren Varianten Spritzpressen und Spritzprägen verarbeitet. Wie in anderen Industriezweigen hat auch hier der wachsende Kostendruck zu einer steten Weiterentwicklung dieser Verfahren geführt. Über erfolgreiche Verfahrensverbesserungen zur Reduzierung der Herstellkosten wird im folgenden berichtet.

Die Einführung der Spritzgießverarbeitung für Duroplaste in den 60er Jahren bedeutete gegenüber der bis dahin ausschließlich betriebenen Preßverarbeitung einen erheblichen Rationalisierungsschritt. Die Zykluszeiten ließen sich durch das Aufschmelzen der Formmasse in der Plastifiziereinheit sowie durch das Einbringen von Friktionswärme beim Einspritzvorgang erheblich reduzieren. Heute erlebt die Preßverarbeitung eine Renaissance insbesondere dann, wenn es gilt, hochpräzise Formteile mit minimaler Schwindung und geringstem Verzug herzustellen. Durch Rundtischautomaten, Vorplastifiziergeräte und Entnahmegeräte ließen sich die wirtschaftlichen Nachteile der klassischen Preßverarbeitung weitgehend kompensieren.
Radikalbildung aus Hydroperoxiden in Gegenwart starker Säuren
Authors: Dulog Lothar , Höfer Hans‐Joachim , Schober Hans‐Jörg
Published: April 2003

The polymerisation of styrene and methylacrylate initiated by hydroperoxides is accelerated in the presence of strong acids such as sulfuric acid, p‐toluene‐sulfonic acid or perchloric acid. By copolymerising styrene and methylmethacrylate and by phenolic type inhibitors the radical nature of the catalytic effect of the acid was proved. Kinetic experiments demonstrated the acid involvement in the starting reaction.
2H‐NMR relaxation studies of reactive intramolecularly crosslinked macromolecules
Authors: Bauer H. , Müller K. , Kothe G. , Funke W.
Published: April 2003

Selectively deuterated intramolecularly crosslinked macromolecules were studied by dynamic 2H NMR spectroscopy. By performing various relaxation experiments detailed information about the molecular mobility of the various components of the polymer chains could be obtained. In particular, the NMR investigations revealed significant effects of molar mass or degree of isomerization on the motional characteristics.
UNTERSUCHUNG PRAXISRELEVANTER EIGENSCHAFTEN VON PP—BLENDS
Authors: Kloos Friedrich , Strouk Hervé , Uebe Rudolf , Heufer Gert
Published: April 2003

The 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

Different 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

It 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

The 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

In 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

The 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.
Einsatz der statistischen Versuchsplanung in der Aminoplast‐Chemie
Authors: Petersen Harro
Published: April 2003

Es wird der Einsatz der statistischen Versuchsplanung für die Optimierung der Herstellung von Aminoplast‐Komponenten und einiger anwendungstechnischer Verfahren beschrieben.
NIEDER‐ UND HOCHMOLEKULARE RADIKALKATIONEN VON CHINOXALINDERIVATEN
Authors: Quarg Gunter
Published: April 2003

Chinoxaline 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

New 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

Poly‐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

To 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

The 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

A 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

Prepolyurethanes 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

Zur 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.