bluuebunny/crossref_metadata_2025 huggingface dataset:
From two‐dimensional model networks to microcapsules
Authors: Burger Andreas , Rehage Heinz
Published: April 2003

The tensio‐active properties of different types of diesters can be used to synthesize two‐dimensional model networks at the interface between oil and water. We have systematically studied rubber‐elastic, glass‐like and transient membrances which are stabilized and crosslinked by physical or chemical contacts.

The adsorption process of the monomeric diesters was investigated by measuring the interfacial tension at the boundary between oil and water. The experimental results can be interpreted on the basis of the “Szyskowski”‐ equation which holds for monomolecular films under ideal conditions. From the measured values of the interfacial tension it is possible to determine the surface concentration. The polymerization process occurs through radical‐reactions which can be initiated by UV‐irradiation.

We have systematically studied the kinetics of surface gelation by measuring the two‐dimensional shear modulus as a function of the reaction time. The experimental results can be interpreted in the framework of simple reaction mechanisms. The quantitative analysis of the experimental data allows to evaluate many details of the photo‐reaction as the free radical concentration. the number of linear chains and the rate constant of the cross‐linking process.

The two‐dimensional sol‐gel transition can easily be described in the framework of percolation theories which were proposed by Stauffer and de Gennes. According to these models, one expects to find a steep increase in the elastic modulus after passing the gel point. The two‐dimensional percolation exponent, determined in our experiments, agrees very well with the calculated result of 4/3. This holds for rubber‐elastic and glass‐like membranes.

Rubber‐elastic, cross‐linked films exhibit interesting features, which can be explained by simple models. The shear modulus depends upon the surface concentration of elastically effective chains. The interfacial polymerization is not restricted to flat surfaces, and the corresponding films can be used for the stabilization of different types of emulsions. Oil droplets which are surrounded by cross‐linked membranes, from simple systems which exhibit interesting properties of biological cells. The microcapsules can, for instance, be used in order to simulate blood flow in living vessels. We have measured the deformation process and the aggregation behavior of these microcapsules in Couette flow under a microscope, and we have investigated the influence of the membrane elasticity on the flow behavior of these emulsions. The data, thus obtained, can be compared with the particle behavior of rigid spheres and deformable liquid drops. The rheological properties of these artificial cells are useful to get a clearer picture of the complicated flow processes which occur in biological systems.
Stress‐optical behaviour of miscible poly (methyl vinyl ether)‐cross ‐ polystyrene semi‐IPN's above the glass transition temperature
Authors: Müller Gunther , Stadler Reimund
Published: April 2003

Semi‐IPN's of different composition, based on linear poly(methyl vinyl ether) (PVME) and crosslinked polystyrene are studied using stress and birefringence measurements in simple elongation. From quasistatic stress‐strain experiments at constant T(experiment)‐Tg, it can be deduced that the stress results only from the deformation of the polystyrene network, while the PVME chains do not contribute to the macroscopic stress. The concentration dependence of the network modulus is adequately described by the rubber elastic theories. In the concerntration range between 20 and 60 wt.‐% of polystyrene the obtained optical anisotropy parameter is different to the value of pure polystyrene and the absolute value decreases with increasing PVME content. Based on the mechanical response and the stress‐optical behaviour of a radically crosslinked pure PVME network possible explanations for the observed behaviour of semi‐IPN's are discussed.
Schwefelvernetzungssysteme und netzwerkstrukturen im überblick
Authors: Engels Hans‐Wilhelm , Eisele Ulrich
Published: April 2003

Sulfur crosslinking systems are well established for curing of rubbers containing olefinic bonds and are well optimized for various processing and end product requirements. This is achieved by the clever selection of accelerator or their combinations or varying sulfur to accelerator ratio. This ratio defines primarily the structure and density of the sulfur crosslinks. Semi efficient crosslinking systems allow in NR as in SBR best compromise of properties with respect to processing, static and dynamic behaviour and ageing. In NR the structure of the crosslinks contrary to SBR has a larger influence on dynamic crack propagation. Polysulfidic crosslinks are preferred for higher tensile strength, tear and fatigue resistance.

Great challenges for accelerated sulfur crosslinking exist to meet new ecological and toxicological requirements such as avoidance of nitrosamines in rubber industry. The present work shows that there is a potential for new developments in the classical sulfur vulcanization to satisfy the present needs and meet the future challenges.
Polymer systems for tires
Authors: Schnecko H.
Published: April 2003

Todays tires are formed from a multitude of very different components of which polymers constitute ca. 60%. The report centers on some developments in elastomers, viz. natural rubber (NR) polybutadiene (BR) and polyisoprene (IR), the various styrene‐butadiene rubbers (SBR) and their blends and some other copolymers. On the part of polymeric organic fibers, only a brief glance is thrown on newer polyamides.
Struktur‐eigenschafts‐zusammenhänge für poly(butadien‐g‐styren) ‐ modell‐polymere
Authors: Frank Willy , Arnold Manfred
Published: April 2003

In order to ascertain structure‐property‐relationships of poly(butadiene‐g‐styrene) copolymers the preparation of these model copolymers has been carried out by the anionic copolymerization of butadiene and styryl‐terminated polystyrene macromonomers in solution. With this method it is possible to determine exactly the graft length and to vary the graft density or the polystyrene content. Besides, the products are almost free of homopolystyrene and are not cross‐linked. The almost statistically regular distribution of the polystyrene grafts along the backbone chain has been achieved by the application of the initiator system: sodium tert‐butoxide/n‐butyl lithium.

The materials have been tested by the determination of selected mechanical characteristic values. They yielded the following relationships:

maxima of properties (stress strain, hardness, elasticity) already appear in the range of molar mass of the PS‐grafts from 5 000 to 8 000 g/mole

the position and the width of the maxima depend on the PB/PS‐phase ratio

with increasing PS‐content, the tensile strength increases up to about 20 MPa at nearly 40 %

the hardness of the products is strongly and linearly influenced by the PS‐content

the elasticity shows a maximum in the range of 20 to 25 % PS‐content.

All in all, the materials exhibit good thermoelastoplastic behaviour in comparison with the SBS‐three or ‐star block copolymers.

Electron microscopic examination of the products result in phase separation phenomena.
Strain‐induced crystallisation and miscibility behaviour of hydrogenated nitrile rubbers
Authors: Braun D. , Haufe A. , Leiß D. , Hellmann G. P.
Published: April 2003

HNBR rubbers, which are made by selective hydrogenation of the olefinic bonds of NBR rubbers, have been developed, because they show improved resistance towards heat and chemicals. In this study, two other properties are discussed that arise from the fact that HNBR rubbers are fairly alternating copolymers of unpolar butylene and polar acrylonitrile units: At intermediate compostions, HNBR rubbers form homogeneous blends with PVC, and near the symmetric composition they exhibit strain‐induced crystallisation. The thermal transitions of the HNBR rubbers and their miscibility with PVC were analyzed, as well as the crystallisation and the stress‐strain behaviour of a HNBR of symmetric composition.
Rubber‐elastic mesophase siloxane systems
Authors: Godovsky Yuli K.
Published: April 2003

Thermotropic poly(diethylsiloxane) is a new type of the mesophase elastomers. Mechanical Measurements in extension and contraction and stretching calorimetric measurements of heat and energy effects resulting from extension and contraction were combained with thermo‐mechanical measurements under constant loads and opto‐mechanical measurements to obtain molecular understanding of the deformational behaviour of these mesophase rubber‐like materials in a wide temperature range with particular emphasis on the temperature range of the mesophase stability as a function of extension. The stress‐strain curves of semi‐mesomorphic films resemble the strain‐strain behaviour of crystalline polymers with a very low degree of crystallinity. During stretching of amophous films the strain‐induced mesophase occurs. The influence of stress on the temperature range of the stability of the strain‐induced mesophase is very strong due to a very small heat of isotropization. The cyclic deformations of the mesophase elastomers are accompanied by the necking‐renecking phenomena resulting from the train‐induced mesophase formation on stretching followed by the immediate isotropization during contraction. Some potential practical applications of the mesophase elastomers are considered.
Neue silikonkautschuke
Authors: Gruber H. , Mössl E. , Kazemi H. , Greber G.
Published: April 2003

Hydrophilic silicone rubbers have been prepared using allyl derivatives of glucose and sucrose resp. as unsaturated components in crosslinking of commercially avaliable RTV silicone components. Silicone rubbers with good tissue tolerance were obtained by covalent bonding of modified SiO2 fillers to the silicone matrix as well as by application of SiO2 fillers modified with anticoagulants.
Chain architecture and molecular self‐organization of polyurethanes: Perspectives for thermoplastic elastomers
Authors: Eisenbach C. D. , Heinemann T. , Ribbe A. , Stadler E.
Published: April 2003

Segmented polyurethanes with a regular chain architecture exhibit very specific self‐organizing properties, often leading to multiphase systems with special phase structures. The study of a series of relatively stiff, monodisperse polyurethane model compounds of various molecularly engineered structures and also multiblock copolymers consisting of an alternating sequence of highly flexible polyether and the above polyurethane segment has shown that extended chain crystallization and chain folding of hard segments and thus the size, shape and ordering of the hard domains can be created and rearranged at will. The molecular design, which can also be applied to graft copolymers, predetermines the possibilities of supramolecular organization. These thermoplastic elastomers exhibit very special properties which correlate sysmatically with the supramolecular structure.
Einfluss des polymerrückgrats auf eigenschaften von thermoplastischen elastomeren
Authors: Schirle Maria , Beckmann Jörg , Stadler Reimund
Published: April 2003

4‐Urazoyl benzoic acid groups were statistically attached to various hydrocarbon elestomers, polar elastomers and partially crystalline polymer via a polymer‐analogous reaction. Thermal analysis (DSC), infrared spectroscopy (FT‐IR), stress‐strain experiments and dynamic‐mechanical analysis were used to analyses whether these systems, analogous to functionalized polybutadienes, would form ordered supramolecular structures of the polar side‐groups that would lead to a thermoreversible crosslinking. While the structure formation is suppressed for elastomers with a large cross‐sectional area of the chain(e.g. butyl rubber) or polar side‐groups (e.g. polychloroprene), the mechanical properties can be controlled by balancing supermolecular structure formation and crystallization in the case of polyoctenamer.
Molecular motion, phase separation and internal surfaces in rubberelastic polymers
Authors: Spiess H. W.
Published: April 2003

The highly selective information provided by solid‐state NMR on molecular motions, phase separation and internal surfaces in elastomers is demonstrated by three examples: i. phase separation and interfacial regions in poly(styrene‐b‐methylphenylsiloxane) diblock copolymers, ii. packing effects, phase separation and internal surfaces of the hard segment aggregates in segmented model polyurethanes containing piperazine rings, and iii. interaction of polydimethylsiloxane elastomers with aerosil filler particles.
Preparation and characterization of heat, oil and fire resistant (HOFR) cable sheathing compounds from compatibilized polychloroprene‐ethylene‐propylene‐diene rubber blends
Authors: Kalidaha Amiya K. , De Prajna P. , Bhattacharyya Arabinda S. , Sen Achintya K.
Published: April 2003

Preparation of heat, oil and fire resistant (HOFR) cable sheathing compounds is attempted by blending polychloroprene (PCP) and ethylene‐propylene‐diene terpolymer (EPDM) using dibutyl maleate grafted EPDM (EPDMgDBM) and chlorinated polyethylene (CPE) as compatibilizer. Cure rate incompatibility has been minimised by adding the curing agents in masterbatch form. Curing characteristics of the blends have been determined by Monsanto Rheometer and Brabender Plasticorder. Morphology of the blends and compatibility have been studied by scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Thermal properties of the blends have been characterized by ageing studies.

The optimized blends, after modification with suitable fillers and other ingredients, possess better properties than the control PCP‐compound and meet the specification BS 6899‐84.
Structural and rheological investigation of low density polyethylenes
Authors: Ondáš Miroslav , Špirk Eugen
Published: April 2003

Some low density polyethylenes (LDPE) with different melt flow index (MFI) or produced by different producers have been examined in detail by solvent gradient fractionation, 13C NMR analysis, FTIR spectroscopy and melt rheological measurements. It was found that the distribution curves of the samples resemble Wesslau's logarithmic‐normal model. From branching analyses it can be concluded that the branching content in the analyzed LDPEs is independent from the molecular weight. Relations between viscosity curve parameters and molecular structure have been investigated. It has been found that the dependence of the first normal stress difference on the shear stress is influenced by polydispersity as well as by the character of samples branching.
An automated high pressure capillary rheometer with hydraulic drive
Authors: Schurz Josef , Prassl Josef , Ribitsch Volker
Published: April 2003

A new capillary rheometer design is described, in which a hydraulic device is used to produce the pressure driving the sample fluid through capillaries. The device is fully automated and controlled by a PC unit. Various measuring modes can be preselected and are automatically executed. Some preliminary results with New tonian fluids and with polymer solutions show the functioning of the new rheometer.
Zinkacrylat und andere feste Monomere als Vernetzungsmittel für ungesättigte Polyester
Authors: Królikowski Wacław , Nowaczek Wiesława , Penczek Piotr , Rudnik Ewa
Published: April 2003

Die Peroxid‐initiierte Copolymerisation eines ungesättigten Polyesters mnit Zinkacrylat, Diallylphthalat‐Prepolymer und einem Vinylesterharz wurde untersucht. Der Härtungsverlauf wurde anhand der Gelierungskurven und mitels Differentialkalorimetrie verfolgt. Die Prüfungen zeigten, daß Zinkacrylat die größte Reaktivität hat.
Copolymers of anionic polymerization of octanelactam with laurolactam. II. Kinetics of isothermal crystallization
Authors: Arvanitoyannis I. , Kehayoglou A. H.
Published: April 2003

The isothermal crystallization kinetics of the anionic copolyamides of ω‐octanelactam (OL) with ω‐laurolactam (LL) (nylon‐8/nylon‐12), covering a wide composition range (0/100 – 100/0 OL/LL, mol/mol), was established according to the Avrami equation by the use of differential scanning calorimetry. The crystallization parameters half‐time crystallization (t1/2), Avrami index (n), rate constant (k), and reduced crystallinity were determined for various crystallization temperatures. These parameter values are correlated to the composition of the copolyamides, the crystallization and supercooling temperature, and the results are discussed.

Differences in kinetic parameter values between the homopolymers of this paper and those for the hydrolytic nylon‐8 and nylon‐12 reported in literature were observed and discussed.
Zur Optimierung der Synthese von Poly(p‐phenylen‐1,3,4‐oxadiazol) in Oleum
Authors: Leibnitz Eberhard
Published: April 2003

Die Reproduzierbarkeit der Synthese von Poly(p‐phenylen‐1,3,4‐oxadiazolen) in Oleum Kann durch eine veränderte Monomerzugabetechnik, gemessen an der Standardabweichung der relativen Lösungsviskosität, um eine Größenordunung verbessert werden. Die Polykondensation verläft unter deutlich milderen Bedingungen in kürzeren Reaktionszeiten zu Polymeren mit höheren Molmassen als nach der bekannten Methode.

Der Einfluß verschiedener Parameter auf die Reaktionsgeschwindigkeit und das Polykondensationsgleichgewicht wurde eingehend untersucht. Auf der Basis streulicht photometrischer und viskosimetrischer Messungen an Polymerlösungen in konzentrierter Schwefelsäure wurde eine [η]/Mw‐Bezeihung ermittelt.
Antibacterial activity of copolymers of trialkyl(4‐vinylbenzyl)ammonium chlorides with acrylonitrile
Authors: Senuma Masao , Iwakura Masahiro , Ebihara Shigeyoshi , Shimura Yukio , Kaeriyama Kyoji
Published: April 2003

Homopolymers of cetyldimethyl(4‐vinylbenzyl)ammonium chloride (VB16), lauryl‐dimethyl(4‐vinylbenzyl)ammonium chloride (VB12), and trimethyl (4‐vinylbenzyl)ammonium chloride (VB1), and copolymers of these compounds with acrylonitrile were examined for antibacterial activity using B. subtilis, S. aureus, E. coli, and P. aeruginosa. All homopolymers and copolymers showed germicidal action to the bacterias, especially strong action to gram‐positive B. subtilis and S. aureus. The strength of the germicidal action of the quaternary ammonium branches was in the order: VB16 > VB12 ≫ VB1.
A new supertough epoxy formulation with high crosslinking density
Authors: Martuscelli E. , Musto P. , Ragosta G. , Scarinzi G.
Published: April 2003

A highly crosslinked thermosetting epoxy resin was modified by a reactive blending process carried out in the presence of bisphenol‐A polycarbonate (PC). FTIR spectroscopy investigations demonstrated that the presence of PC in the blend decreases the reactants conversion after the curing and postcuring processes. Moreover, it was found that the fracture toughness of this blend system increases markedly by increasing the PC content in the blend. No evidence of phase separation of the minor component during the crosslinking reaction steps was observed.
Interpenetrierende Polymernetzwerke aus ungesättigten Polyesterharzen und Dian‐Dicyanat
Authors: Penczek Piotr , Mirkowska Bożenna
Published: April 2003

Interpenetrierende Polymernetzwerke (IPN) wurden durch die gleichzeitige Vernetzung ungesättigter Polyesterharze und Dian‐Dicyanat erhalten. Die Copolymerisation von ungesättigtem Polyester mit Styrol erfolgte nach dem radikalischen Mechanismus, während das Dian‐Dicyanat cyclotrimerisierte, wodurch sich ein Polytriazin(Polycyanurant)‐ Netzwerk bildete. Die IPN zeichnen sich durch erhöhte Glastemperatur und mechanische Festigkeit im Vergleich zum entsprechenden ungesättigten Polyesterharz ohne Dian‐Dicyanat‐Zusatz aus.
Preparation and properties of silicon‐containing copolymers for near‐UV resists, II. Poly[(N‐(4‐hydroxyphenyl)maleimide)‐alt‐(p‐trimethylsilyl‐α‐methylstyrene)]
Authors: Chiang Wen‐Yen , Lu Jin‐Yuh
Published: April 2003

Poly[(N‐(4‐hydroxyphenyl)maleimide)‐alt‐(p‐trimethylsilyl‐α‐methylstyrene)] (α‐PHTMMS) and several N‐(4‐hydroxyphenyl)maleimide ‐alt‐p‐α‐methylstyrene related copolymers were synthesized for novel positive near‐UV resists containing diazonaphthoquinone sulfonate (DNS). The chain‐stiffening effect of the maleimide group was responsible for high thermal resistance. Thus, a high glass transition temperature of 240°C and thermal decomposition temperature of 425°C were obtained. Lithographic positive images were obtained which resisted thermal deformation at 250°C. The prepared silicon‐containing resists were also used as the top imaging layer of a bilayer resist for microlithographic application.
On the polymerization of styrene in the presence of some benzanthrone dyes
Authors: Konstantinova Temenuschka , Bojadgieva Jordanka
Published: April 2003

The polymerization of styrene in the presence of some fluorescent dyes, benzanthrone derivatives, has been investigated. The dependence of the polymerization rate of styrene on the character of the dye was determined. It was found spectrophotometrically that 70 – 80% of the dye reacted in the polymerization, thus the coloured fluorescent polymers were obtained. They are resistant to wet treatment and decolouration by solvent. The incorporation of the dye into the polymer chain does not significantly affect the molecular weight and polydispersity of the coloured polymers.
The influence of sepiolite on the dynamic moduli and thermal transition of compatible and incompatible blends based on poly(vinylidene fluoride)
Authors: Herrero Consuelo R. , Morales Enrique , Acosta Jose Luis
Published: April 2003

This paper reports on a study of dynamic moduli and thermal transitions of poly(vinylidene fluoride) in compatible blends with poly(methylmethacrylate) and in non‐compatible blends with polystyrene. The effects of sepiolite on the compatibility of these blends have been studied.
Poly(butyl acrylate) inclusive polymerization in the presence of bacterial polyesters, 1. Synthesis and preliminary mechanical and morphological characterization
Authors: Avella M. , Immirzi B. , Malinconico M. , Martuscelli E. , Orsello G. , Pudia A. , Ragosta G.
Published: April 2003

Linear polyesters of 3‐hydroxybutyric acid (PHB) and its copolymers with 3‐hydroxyvaleric acid (PHBV) are produced by the fermentation of glucose by the bacterium Alcaligenes Eutrophus1,2. Their large‐scale commerical development is severely limited, until recently, by the prohibitive cost, narrow processability window (Tdeg–Tm), and, above all, the low impact resistance around room temperature and below due to very high crystallinity and relatively high glass transition temperature.

This paper reports on an attractive route to impact modification of PHBV by a reactive blending method. Interesting improvements are obtained by using 30 wt.‐% of acrylate rubber. Correlations are found between mechanical response and morphology of blends.
Solid‐state orientation studies on polypropylene disks, 1. Uniaxial compression with non‐lubricated press platens
Authors: Bruce G. D. , Weatherly G. C. , Vancso G. J.
Published: April 2003

The molecular orientation in isotactic polypropylene disks compressed uniaxially in the solid state using non‐lubricated press platens was studied by measuring optical birefringence and infrared dichroism. The orientation profile was inhomogeneous through the disk thickness and was dependent on the radial distance from the disk axis. The results indicate that, near the disk surface, the polymer chains in the crystalline regions are oriented parallel to the radial direction, while the chain direction becomes gradually perpendicular to the disk surface near the mid‐thickness at the disk. There is consequently a continuous rotation of the chain direction in the crystalline phase between these extremes, with the orientation factor going through zero. The formation of this orientation profile is explained by the observed fountain‐flow conditions during the compressive deformation. Mechanical failure of the specimens cut in the radial and in the tangential directions was usually initiated at the mid‐plane of the disks. This unusual behavior was attributed to the predominantly perpendicular orientation of the macromolecules in the polymer crystallites near the mid‐plane of the oriented disks.
Solid‐State orientation studies on polypropylene disks, 2. Uniaxial compression with lubricated press platens
Authors: Bruce G. D. , Snétivy D. , Weatherly G. C. , Vancso G. J.
Published: April 2003

The molecular orientation of isotactic polypropylene disks compressed uniaxially in the solid state using lubricated press platens was studied by measuring optical birefringence, infrared dichroism and wide‐angle x‐ray scattering. Differences in anisotropy obtained by optical birefringence and infrared dichroism were negligibly small throughout the disk at a low overall level of orientation. Pole figures obtained from WAXS measurements showed that the orientation texture developed during the deformation was essentially planar with polymer chains oriented perpendicularly to the compression direction.
New silicone rubbers, 1. Hydrophilic silicone rubbers
Authors: Mössl Eva , Gruber Heinrich , Greber Gerd
Published: April 2003

3‐O‐Allylglucose (1), allylglucoside (2) and sucrose‐allylether‐mixtures (3), respectively, protected by trimethylsilyl (TMS)‐groups have been used as unsaturated components in crosslinking of commercially available RTV silicone components. The resulting hydrophobic silicone rubbers were converted into hydrophilic types with covalently bonded sugar residues by hydrolysis to split off the TMS‐groups. Silicone rubbers with glucose residues exhibited equilibrium water contents (EWC) from 2 to 9% dependent on the molar ratio of 1 and 2, respectively, to the Si‐vinyl component. The mixtures 3 can be used as crosslinking agent without additional Si‐vinyl component to give EWC's of more than 30%.
New silicone rubbers, 2. Biocompatible silicone rubbers
Authors: Kazemi‐Shirazi Helen , Gruber Heinrich , Greber Gerd
Published: April 2003

Biokompatible silicone rubbers have been prepared using fillers based on two types of modified amorphous silica: (i) silica containing covalently bonded reactive H‐Si‐groups (1) obtained by reaction of silica with methyldichlorosilane, and (ii) silica with covalently immobilized antithrombogenic agent (5), prepared by reaction of 1 with divinylbenzene, graft copolymerization with acrylic acid and subsequent esterification with amylose sulfuric acid esters (2) as a heparinoid.

Silicone rubbers (SR's) were obtained by hydrosilation curing of commercially available silicone components using 1 or 5 as fillers. In contrast to 5, 1 is incorporated covalently into the silicone network. Both SR types exhibited good mechanical properties as well as excellent tissue compatibility: contrary to SR's filled with nonmodified silica the cell growth of endothelian cells on the SR's with modified fillers was found to be almost identical to that on cell culture plates.
Zerstörungsfreie Prüfung von Polymeren mittels photothermischer Meßmethoden. 2. Photoakustische untersuchungen von Polyesterfärbungen in Abhängigkeit von der Farbstoffkonzentration und der Oberflächenrauheit
Authors: Eickmeier Achim , Schollmeyer Eckhard
Published: April 2003

Im Bereich der textilen Analytik bereitet die Bestimmung der Farbstoffkonzentration dunkler und gesättigter Fäbungen große Schwierigkeiten. Deshalb wird die Einsatzmöglichkeit der photoakustischen Spektroskopie zur Charakterisierung von Fäbungen zn Konzentrationseichreihen systematisch untersucht. Die Meßergebnisse wurden mit einer modifizierten Kubelka‐Munk‐Funktion angepaßt, die über einen größeren Konzentrationsbereich linear verläft als bei der Reflexionsspektroskopie. Weiterhin wurde der Einfluß der Oberflächenstruktur auf das photoakustische Signal untersucht.
Kinetics analysis of the curing of a diepoxy‐diamine system
Authors: Mathieu Christophe , Seytre Gérard , Boiteux Gisèle , Fève Michel
Published: April 2003

The reaction between the diglycidylether of bisphenol A (DGEBA) and 4,9‐dioxa‐1,12‐dodecanediamine (DDDD) has been studied by means of isothermal and dynamic differential scanning calorimetry. The enthalpy of the reaction of an epoxy group with an amino‐hydrogen has been determined to be 112 ± 5 kJ/mol. A kinetic model has been validated. It involves two competitive mechanisms: one is catalysed by the hydroxy groups initially present on the epoxy chain or generated during the reaction (activation energy 77 ± 5 kJ/mol), the other is not catalysed with a higher activation energy (103 ± 3 kJ/mol).

For each isothermal curing, the kinetics are not modified by gelation. Evaluated from the gel times, the overall activation energy of the reaction is equal to 62 ± 2 kJ/mol.
New flame‐retardant poly(pyromellitic imide aryl phosphoramide‐ester)s
Authors: Kannan Palaninathan , Kishore Kaushal
Published: April 2003

Flame‐retardant poly(pyromellitic imide aryl phosphoramide‐ester)s were synthesized by interfacial polycondensation of N,N′‐bis(p‐hydroxyphenyl)pyromellitic diimide with aryl phosphoramidic dichlorides. The polymers were characterized by IR and 1H‐NMR spectroscopy. The molecular composition was confirmed by elemental analysis. The thermal stability and flammability of the polymers were studied by thermogravimetry and limiting oxygen index, respectively.
Graft copolymers having hydrophobic backbone and hydrophilic branches, 8. Effect of temperature on the dispersion copolymerization of poly(ethylene glycol) macromonomer with styrene
Authors: Riza Medyan , Capek Ignac , Kishida Akio , Akashi Mitsuru
Published: April 2003

Copolymerization of poly(ethylene glycol) macromonomers with terminal meth‐acryloyl groups with styrene was carried out in the presence of 2,2′‐azobis(N,N′‐dimethyleneisobutyramidine) in ethanol/water mixture (4:1, v/v) at various temperatures. The overall activation energy for the dispersion copolymerization was obtained as 48 kJ/mol.
Compatibilization of poly(2,6‐dimethyl‐1,4‐phenylene ether)/poly(vinylidene difluoride) blends
Authors: Viersen Frits Jan , Colantuoni Paul , Mamalis Ilias
Published: April 2003

Standard available PPE was modified to contain methacrylate‐functional groups. Radical copolymerization of these with methylmethacrylate (MMA) yielded a PPE/PMMA copolymer, suitable as compatibilizing agent in PPE/PVDF blends. Addition of PPE/PMMA copolymers (composition by weight 40/60) at just 5–10 wt.‐% levels gave a very good dispersion of the PVDF minor phase in a PPE/PS matrix. The most effective PPE/PMMA copolymer was found to be the one containing PPE‐pendent chains along PMMA. This copolymer can be made from PPE modified to contain only one methacrylate‐functional group per PPE chain. Adding 10 wt.‐% of this PPE/PMMA copolymer resulted in a blend with thermally stable morphology.
Der Einfluß des Photoinitiators auf die radikalische Härtung von Siliconacrylaten, 9
Authors: Müller Uwe , Vallejos Carlos
Published: April 2003

Die photoinduzierte radikalische Vernetzung von Siliconacrylaten wurde mit verschiedenen Photoinitiatoren vom Benzoyltyp untersucht. Die Photovernetzung derartiger Produkte kann mit Hilfe eines radikalischen Kettenprozesses beschrieben werden. Aus kalorimetrischen Messungen folgt, daß Sauerstoff den Kettenprozeß inhibiert und terminiert, wobei dei Vernetzungsgeschwindigkeit und die Inhibierungszeit Funktionen des Luftdrucks, der Lichtintensität und der Quantenausbeute der Initiatrophotolyse sind.

Der Vernetzungsprozeß kann nur beginnen, wenn der Sauerstoff in der Schicht verbraucht ist. Mit Hilfe des 1. Fickschen Diffusionsgesetzes kann gezeigt werden, daß der in das System eindiffundierende Sauerstoff auch den Grenzumsatz bestimmt.

Obwohl Sauerstoff in der Schicht die Reaktionsgeschwindigkeit, die Inhibierungszeit und den Grenzumsatz bestimmt, wurde jedoch überraschenderweise festgestellt, daß Sauerstoff auf die Netzwerkdiche keinen Einfluß besitzt.

Der negative Effekt des Sauerstoffs auf den Vernetzungsprozeß kann durch eine hohe Startgeschwindigkeit (Funktion der Lichtintensität, der Absorption und der Quantenausbeute der Initiatorphotolyse) reduziert werden.

Mit Hilfe von zwei kinetischen Methoden wurde ermittelt, daß die Initiierungseffizienzen der verwendeten Initiatoren verschieden sind, wobei relative Abstufungen bestimmt werden konnten.
The reaction of 1‐cyano‐1‐methylethyl radical with antidegradant ethoxyquin and its aminyl and nitroxide derivatives
Authors: Taimr Luděk , Šmelhausová Marcela , Prusíková Miluše
Published: April 2003

6‐Ethoxy‐2,2,4‐trimethyl‐1,2‐dihydroquinoline (ethoxyquin, I) does not react with the model alkyl radical, 1‐cyano‐1‐methylethyl, in an inert atmosphere. On the other hand, its aminyl derivative (II) reacts readily with the model alkyl radical; the main product of this reaction is 6‐ethoxy‐8‐(1‐cyano‐1‐methylethyl)‐2,2,4‐trimethyl‐1,2‐dihydroquinoline (V), while 6‐ethoxy‐1‐(1‐cyano‐1‐methylethyl)‐2,2,4‐trimethyl‐1,2‐dihydroquinoline (VI) is formed as a by‐product. 6‐Ethoxy‐2,2,4‐trimethyl‐1,2‐dihydroquinoline‐N‐oxyl (III) also effectively deactivates the model alkyl radical to form 6‐ethoxy‐ 8‐(1‐cyano‐1‐methylethoxy)‐2,2,4‐trimethyl‐1,2‐dihydroquinoline (X).

It follows from these results that I is an ineffective antidegradant in oxygen‐free atmosphere. However, at very low oxygen concentrations, I becomes capable of deactivating alkyl radicals. Together with its ability to deactivate alkylperoxide radicals, this explains the high antifatigue activity of I.

In the presence of silica gel, V is readily cyclized to 8‐ethoxy‐1,2,3,4‐tetrahydro‐2‐imino‐1,1,4,4,6‐pentamethylpyrrolo[3,2,1‐ij]quinoline (VIII). VI undergoes thermal decomposition into its components, i.e., aminyl II and the model radical. Photodecomposition of X on silica gel yields 6‐ethoxy‐2,2,4‐trimethyl‐8‐quinolone (XIII).
Magnetic properties of metal layer deposited by reduction of polymer containing metal ions
Authors: Yosomiya Takatoshi , Sato Yoshihiro , Yosomiya Ryutoku
Published: April 2003

Magnetic properties of metal layer deposited by reduction of polymer containing metal ions were investigated.

Varying the ratio of the cobalt ion to the nickel ion in the polymer, the coercivity, the maximum flux density and the remanent flux density of the deposited metal layer were changed from 100 to 600 Oe, from 1 000 to 12 600 G and from 500 to 7 600 G, respectively. The X‐ray diffraction pattern of the metal layer with excellent magnetic properties gives distinct peaks corresponding to the (101) and (100) planes of the crystal of α‐Co.

This suggests that such a deposited metal layer has the structure of highly crystalline metal layer.
Preparation and characterization of a mercaptan derivative of chitosan for the removal of mercury from brines
Authors: Argüelles‐Monal W. , Peniche‐Covas C.
Published: April 2003

Chitosan, [(1,4)‐2‐amino‐2‐deoxy‐β‐D‐glucan], was reacted consecutively with epichlorohydrin and thiourea. Subsequent hydrolysis of the isothiouronium salt yielded the mercaptan derivative of chitosan, which scavenges mercury ions from solution in the presence of a considerably high concentration of chloride ions.

Sulfur contents varied with reacting conditions and reached values up to 7.3%. The derivative is insoluble due to partial crosslinking of chitosan during the reaction with epichlorohydrin and was characterized by IR spectroscopy, solid‐state 13C NMR, thermal analysis and pyrolysis‐mass spectrometry.
Phenomenological model for the unified studies of different physical properties of polymers
Authors: Dutta Tapati , Biswas Prabir Kumar
Published: April 2003

A phenomenological model has been proposed to understand the development of strong anisotropy in physical properties of semicrystalline polymers on uniaxial drawing. The proposed model introduces temperature as an explicit parameter in the orientation function. The model contains two free parameters for each polymer which can be evaluated by fitting the experimental data on birefringence versus draw ratio at a particular temperature. The calculated values of elastic moduli, thermal conductivity and expansibility along and perpendicular to the drawing direction over the entire range of draw ratio and a wide range of temperature are in good agreement with experimental values.
Radical polymerization of mono‐ and di‐methacrylic esters containing bisphenol‐S
Authors: Liaw Der‐Jang , Teng Kuei‐Fei
Published: April 2003

Radical polymerizations of mono‐ and di‐methacrylic esters containing bisphenol‐S (BPS‐M and BPS‐DM) were studied in terms of polymerization rate, solvent effect, copolymerization and kinetic measurements of photocrosslinking. The solvents were found to affect significantly the polymerization rate. Polar solvents such as DMSO and acetonitrile were found to slow down the polymerization rate. Copolymerization of BPS‐M(M1) with MMA(M2) was studied in acetone at 60°C. The monomer reactivity ratios were calculated to be r1 = 3.72 ± 0.01 and r2 = 0.80 ± 0.01 by the Fineman‐Ross method. The high reactivity of BPS‐M observed in this copolymerization system may be due to the “matrix effect”. Functional polymers containing methacrylate side‐groups were successfully modified and photocrosslinked by irradiation in the presence of benzoin isopropyl ether. The photocrosslinking process is found to be of second order kinetics.
Syntheses and reactions of photopolymers, I. New photosensitive azo monomers, photolysis, interfacial polycondensation, viscosity measurements, photodegradation
Authors: Nuyken Oskar , Dauth Jochen , Stebani Jürgen
Published: April 2003

The synthesis of new, unsymmetrically functionalized azo compounds and their incorporation into polymers is described. Their photochemical decomposition and thermal stability was studied by UV spectroscopy and differential scanning calorimetry (DSC), respectively. Chemical degradation was followed by viscosity measurements.
Thermal analysis of oxime‐blocked toluene diisocyanates
Authors: Kothandaraman Harimurthi , Thangavel Ramasamy
Published: April 2003

Oxime‐blocked toluene diisocyanates were synthesized and characterized by infrared spectra, nuclear magnetic resonance spectra, elemental analysis etc. Thermal analyses of blocked isocyanates were done by thermogravimetry. Solubility of blocked isocyanates in various polyols was tested. Formation of isocyanate on heating the blocked isocyanate was identified by gas chromatographic analysis.
Preparation of porous ion‐exchange membranes from sulfonated polyethylene/poly(styrene‐co‐divinylbenzene)
Authors: Bryjak Marek , Trochimczuk Witold M.
Published: April 2003

It was shown that the etching of styrene‐divinylbenzene copolymer from KESD‐2 type ion‐exchange membranes resulted in porous membranes. Modification of such membranes introduced both acidic or basic groups onto the pore surface. The ultrafiltration of bovine serum albumin through these membranes was mostly affected by coulombic interaction. Protein deposition on/in membrane was controlled by charge as well as hydrophilic properties of membranes. In addition, the effect of polystyrene crosslinking degree on the blend morphology was explained. The structure of polystyrene copolymer underwent the qualitative threshold when the crosslinking agent concentration reached the level of 2 wt.‐%.
Water‐soluble polyamides as potential drug carriers, VI. Synthesis of amine‐ and carboxyl‐functionalized carrier polymers by high‐temperature solution polymerization in polyphosphoric acid
Authors: Swarts Jannie C. , Neuse Eberhard W. , Perlwitz Axel G. , Stephanou Andreas , Lamprecht Gert J.
Published: April 2003

Hydrophilic polyamides containing amino or carboxyl groups in the repeat units suitable for drug binding are synthesized by polycondensation of aliphatic dicarboxylic acids, including succinic acid, iminodiacetic acid, and ethylenediaminetetraacetic acid (reacting as a difunctional monomer in these polymerizations), with diamines, such as diethylenetriamine, 1,2‐bis(3‐aminopropylamino)ethane, and the two hydrosolubilizing poly(ethylene oxide) derivatives, α,ω‐bis(2‐aminopropyl)poly(ethylene glycol) 800 (Jeffamine ED‐900) and α,ω‐bis(2‐aminopropyl)poly(ethylene glycol) 1900 (Jeffamine ED‐2001). The reactions are conducted in polyphosphoric acid medium at the optimal temperature range of 150–165°C. The product polymers, fractionated by aqueous‐phase dialysis in 12000–14000 molecular‐mass cut‐off membrane tubing, are isolated by freeze‐drying. Yield data, ranging from 1% to nearly 40% for the material so fractionated, indicate low propensity for polycondensation under these conditions for the volatile diethylenetriamine monomer, and only moderately better performance for the thermally labile Jeffamines, yet satisfactory polymerization behaviour for the bis(aminopropylamino)ethane. The microanalytically and spectroscopically characterized polyamides fulfil the biomedically important requirement of solubility in water; inherent viscosities in this medium are in the approximate range of 5–15 ml · g−1. The drug‐anchoring capabilities of these polymers will be the subject of forthcoming publications.
Determination of carbon black fillers in vulcanizates of natural rubber by metathesis degradation
Authors: Hummel Klaus , Kiattanavith Nilubol , Bernard Erich
Published: April 2003

A method for the determination of carbon black fillers in peroxide vulcanizates or sulfur vulcanizates of natural rubber (NR, cis‐1,4‐polyisoprene) by metathesis degradation with 1‐octene was developed using the catalyst WCl6(C2H5)3Al2Cl3. The carbon black was separated from the reaction mixture by centrifuging and determined by weighing.

In this connection, investigations were also performed with the catalyst WCl6C2H5Al2Cl3 which was less suitable for filler determination. The rate of degradation of crosslinked NR with (E)‐4‐octene was measured. Metathesis reactions of 2‐methyl‐2‐pentene (low‐molecular‐weight model compound of NR) with 7‐tetradecene showed the importance of double bond shift for the degradation of NR.
Radical terpolymerization of ethylene, methyl acrylate and vinyl acetate under high pressure. Physical properties of the polymers
Authors: Luft Gerhard , Stein Franz , Dorn Max
Published: April 2003

Polymerization tests were carried out in a stirred autoclave designed for continuous operation in order to determine the influence of the reaction pressure and temperature and of the acrylic acid methyl ester and vinyl acetate comonomers on the ethylene‐acrylic acid methyl ester‐vinyl acetate terpolymer formed. Pressures between 1100 and 1900 bar and temperatures of 180 and 230°C were used. The average residence time was 40 seconds. Tertiary butyl perpivalate and tertiary butyl perethyl hexanoate in concentrations of 50 to 180 mol‐ppm in the ethylene feed were used as initiators. The characteristic properties of the polymers obtained were assessed by determining their composition, density, crystallinity, melting point, glass transition temperature, melt index, the average molecular weight, tensile strength and elongation at break.
Linear polythioesters, XXIII. Products of interfacial polycondensation of 4,4′‐dimercaptobiphenyl with acid dichlorides
Authors: Podkoscielny Wawrzyniec , Tarasiuk Bogdan
Published: April 2003

New polythioesters were obtained by interfacial polycondensation of 4,4′‐dimercaptobiphenyl with selected aliphatic and isomeric phthaloyl dichlorides.

To determine the optimum polycondensation conditions, the influence of the following factors on reduced viscosity and yield were studied: type of organic phase, concentration of hydrogen chloride acceptor, type of catalyst, reaction temperature and rate of acid dichloride addition.

A thorough examination was carried out only for the polycondensation of dithiol with isophthaloyl dichloride chosen as a model system. The structures of polythioesters were determined by elemental analysis, X‐ray and infrared spectra. The temperature of initial decomposition, the percentage of its mass loss, and temperature of the fastest decomposition process were determined from curves of differential and thermogravimetric analysis.

Some physicochemical, mechanical and electrical properties were determined. The molecular weights were not measured because of the low solubility of the obtained polythioesters.
Cationic surface modification by polyelectrolytes: Polyelectrolyte complex formation at inorganic particle surfaces
Authors: Oertel Ulrich , Schwarz Simona , Buchhammer Heide‐Marie , Petzold Gudrun , Jacobasch Hans‐Jörg , Rätzsch Manfred
Published: April 2003

The surface charge of inorganic finely dispersed materials like diatom earth, perlite, glass or clay may be changed from negative to positive by the adsorption of cationic polyelectrolytes. Different materials exhibit equivalent electrokinetic surface properties with high amounts of the polycation adsorbed. Interfaces modified this way are able to adsorb anionic dye stuffs. Their adsorption capability for the dye stuff may be enhanced by addition of polyanions due to the formation of a nonstoichiometric polyelectrolyte complex (PEC) and therefore an increased number of cationic centres in the interface. Experimental results indicate that the zeta potential is correlated to the outer PEC layer whereby dye stuff adsorption measurements are sensitive for the more inner surface regions, too. Immediately after modification, materials modified with poly(diallyldimethylammonium chloride) and poly(maleic acid‐co‐α‐methylstyrene) have negative zeta potentials at high excess of added polyanion and a positive one after separation of the solid. This behaviour is attributed to the formation of a nonstoichiometric PEC with polycation in excess and reversible interaction with polyanion in the surrounding solution. Experimental results indicate that the surface may act as “solid‐like” polyelectrolyte in competition to the polyanion.
Photooxidative ageing of low density polyethylene. Kinetics determined by an electrical method
Authors: Jelčić Ž. , Mlinac‐Mišak M. , Jelenčić J. , Bravar M.
Published: April 2003

The efficiency of light stabilizers is investigated by electric methods in the initial stage of photooxidative ageing of low density polyethylene (LDPE). Three types of UV light stabilizers are tried to improve the UV stability of LDPE: a phosphite type (3,9‐bis‐[(2,4‐di‐tert‐butyl)phenoxy]‐2,4,8,10‐tetraoxa‐3,9‐diphosphaspiro[5.5]undecane) a benzophenone type [2‐hydroxy‐4‐octyloxy‐benzophenone] and a stabilizer based on chelate salt [2,2′‐thiobis(4‐tert‐octyl phenolato) (n‐butylamine) nickel (II)]. LDPE is very susceptible to ultraviolet light. UV light stabilizers improve the stability of low density polyethylene for electrical applications, especially the UV stabilizer based on chelate salt.
The interfacial polycondensation of tetrabromobisphenol‐A polycarbonate. I. Model reaction and mechanism studies
Authors: Gu Jen‐Tau , Luo Wei‐Chen , Wang Chun‐Shan
Published: April 2003

2,2′,6,6′‐Tetrabromobisphenol‐A (TBBPA), a sterically hindered bisphenol, is known to give only low‐molecular‐weight polymers using the interfacial phosgenation process. The low reactivity is attributed to the bulkiness and electron‐withdrawing character of bromine substituents at the ortho positions. From the formation of carbamate products in model compound (2,4,6‐tribromophenyl chloroformate, TBPC) reactions with trialkylamines, the trialkylamine catalyst was found to act as a terminator by the degradation of the chloroformate‐trialkylamine complex. The generation of carbamate occurs through the decomposition of the acyl ammonium salt proceeding via nucleophilic displacement by Cl− at the carbon attached to the positive nitrogen center. The relative catalytic abilities of trialkylamines and pyridine derivatives were determined in the homogeneous (dichloromethane) and interfacial (dichloromethane/water) systems. From the results of model reactions with TBPC and sodium tribromophenolate, 4‐dimethylaminopyridine (DMAP) was found to be the best catalyst.
The effects of temperature and ionic strength on the cooperative binding of C.I. Basic red 18 with carboxymethyl cellulose
Authors: Pak Soo‐Min , Borsa Judit , Iijima Toshiro
Published: April 2003

The effects of temperature and ionic strength of a solution of C. I. Basic Red 18 on the cooperative interaction with carboxymethylcellulose were investigated by the dynamic dialysis method and the binding parameters were determined. The molecular model of the cooperative binding is presented.