bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kupferdesaktivierende wirkung von chelatkomplexbildnern in strahlenvernetztem polyethylen niedriger dichte
Authors: Schipschack Klaus , Beger Jörg , Neumann Renate , Wagner Harald 
Published: April 2003

AbstractKomplexbildner für Kupfer, die als Nachweisreagenzien in der Analytik und als Reagenzien für die Flüssig‐Flussig‐Extraktion interessant sind, wurden als Kupferdesaktivatoren in vernetztem Polyethylen niedriger Dichte (XLDPE) durch Bestimmung der Induktionszeiten der Sauerstoffaufnahme von XLDPE/Cu/XLDPE‐Sandwichproben bei 165 °C getestet. Neben acylierten Hydrazinen, einer für wirksame Metalldesaktivierung bereits bekannten Stoffklasse, wurden mehrere Gruppen von Chelatkomplexbildnern untersucht, wobei sich vor allem die 2‐(2‐Hydroxyphenyl)imidazole als wirksame Kupferdesaktivatoren in XLDPE erweisen. 2‐(2‐Hydroxyphenyl)oxazol, ‐thiazol und ‐oxadiazol, denen bei sehr ühnlicher chemischer Struktur der bewegliche Wasserstoff am Fünfring fehlt, sind dagegen unwirksam.
High performance polyamide‐6 and blends of poly(ethylene terephthalate) and poly(butylene terephthalate) through ultraquenching
Authors: Avramova Nadka , Fakirov Stoyko , Avramov Issak 
Published: April 2003

AbstractPolyamide‐6 (PA6) and blends of poly(ethylene terephthalate) (PET) and poly(butylene terephthalate) (PBT) characterized by amorphous initial structure and improved mechanical properties are obtained by means of an ultraquenching technique. In the case of polyamide‐6, erasure of the structural memory is achieved by melt annealing above the equilibrium melting point. This procedure is applied in order to restrict the crystallization process. After quenching, further orientation of the amorphous polymers and annealing with fixed ends lead to a significant improvement of the mechanical properties. The tensile strength and elasticity modulus increase three to five times and the elongation at break decreases by half as compared with conventionally obtained polyamide‐6, PET and PBT.
Synthesis of epoxy resins based on bisphenol‐S and its derivatives
Authors: Liaw Der‐Jang , Shen Wen‐Chang 
Published: April 2003

AbstractBisphenol‐S derivatives of five kinds such as bis[4‐(β‐hydroxyethoxy)‐phenyl]sulfone (HEPS), bis[4‐(β‐hydroxy(iso)propoxy)‐phenyl]sulfone (HPPS), 3,3′,5,5′‐tetrabromobisphenol‐S (TBS), bis[3,5‐dibromo‐4‐(β‐hydroxyethoxy)‐phenyl]sulfone (HEETBS) and bis[3,5‐dibromo‐4‐(β‐hydroxy(iso)propoxy)‐phenyl]sulfone (HPETBS) were successfully prepared by the reaction of bisphenol‐S with ethylene carbonate, 1,2‐propylene carbonate or bromine, respectively. Several sulfone‐containing epoxy resins were obtained by alkaline condensation of bisphenol‐S (bis(4‐hydroxyphenyl)‐sulfone) or its derivatives with epichlorohydrin using sodium hydroxide. The epoxy resins thus obtained were characterized by elemental analysis, IR and 13C‐NMR spectra. All epoxy resins are solid products except HPPS epoxy which contains oxypropylene units. The melting points (Tm) and glass transition temperatures (Tg) of epoxy resins which have flexible oxyethylene or oxypropylene units were lower than that of epoxy resin derived directly from bisphenol‐S. The increase of melting point which has been observed in brominated epoxy resins is attributed to the bulky bromine atom. The molar‐mass distributions of epoxy resins made by the direct addition of epichlorohydrin to bisphenol‐S (so‐called “taffy” process) or by the reaction of epoxy resin of low molar mass and of which the main constituent is the diglycidyl ether of bisphenol‐S in melt (so‐called “advancement” process) have also been compared. The “taffy” process leads to products containing both odd‐ and even‐numbered diepoxide oligomers in contrast to the “advancement” process which leads to products containing predominantly even‐numbered diepoxide oligomers. Epoxy equivalent and melt viscosity of epoxy resins increased with increasing amount of bisphenol‐S. This result is in accordance with the theoretical distribution calculated according to Flory statistics.
Ion exchanger resins, I. Anion exchangers with tertiary amine groups on poly(acrylonitrile‐co‐divinylbenzene) networks
Authors: Drǎgan Stela , Grigoriu G. 
Published: April 2003

AbstractMacroporous copolymers of poly(acrylonitrile‐co‐divinylbenzene) were synthesized in the presence of 2‐ethyl‐1‐hexanol (2EH) and toluene as diluents. The copolymers were characterized by acrylonitrile content and from morphological point of view. Samples with a minimum content of homopolymer were transformed into weak base anion exchangers by the aminolysis‐hydrolysis reaction of the nitrile groups with N,N‐dialkylaminoalkylamines. The reactions were investigated by the exchange capacity variation and IR‐spectral analysis. It was emphasized that the reactivity of asymmetrical diamines depends on the nucleophilicity of the primary amine group.
An ATR‐FTIR study on penetration of resins in wood
Authors: Jensen Eirik S. , Gatenholm Paul , Sellitti Claudio 
Published: April 2003

AbstractWood samples were treated with allylic ether resins having various molecular weights, various structures and with the use of different solvents. Using a technique based on Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR‐FTIR), differences in the characteristic bands of wood and resin were monitored throughout a piece of wood treated with resins and thus a penetration profile was demonstrated.ATR‐FTIR showed that there were differences in the chemical composition of the wood itself at different depths from the surface. The resins could be detected at a depth of more than 3 mm into the wood after 4 days of penetration by gravity. Using a characteristic band for wood as an internal standard, it could be demonstrated that penetration depends upon the solvent used, molecular weight of the resin and also morphology of the wood.
Synthesis and properties of porous ion‐exchange membranes, I. Polymer‐polymer‐filler system
Authors: Bryjak Marek , Poźniak Gryzelda , Trochimczuk Witold 
Published: April 2003

AbstractA method of preparation of porous ion‐exchange membranes (PIEM's) with sulfonic groups is presented. One of the four studied polymer blends is recommended for PIEM's preparation. It is the ternary blend of polyethylene with poly(styrene‐co‐divinylbenzene), isotactic polypropylene, and calcium carbonate. The effect of blend composition on membrane properties is also discussed. Both blend components, PP and CaCO3, affected the membrane porosity while only PP governed the pore diameter. A model of PIEM's creation is suggested. The antifouling behaviour of PIEM's was evaluated by means of ultrafiltration of bovine serum albumine or poly(ethylene glycol) solutions as well as skimmed‐milk and an active sludge designated for bioconversion of aldehydes. It was found that membranes with ion‐exchange capacity higher than 1 mmol/g offer antifouling effect. PIEM's have also higher solute rejection parameter and are easier to regenerate than membranes without sulfonic groups.
Lokale mischbarkeit von isotaktischem polypropylen (iPP) und trans‐polyoctenylen (TOR) in grenzschichten von iPP/TOR‐blends
Authors: Wenig W. 
Published: April 2003

AbstractBlends aus isotaktischem Polypropylen (iPP) and trans‐Polyoctenylen (TOR) wurden mit Differentialkalorimetrie, Röntgenweit‐ und ‐kleinwinkelstreuung, Torsionsschwingungsanalyse und Polarisationsmikroskopie (Keimbildung und Kristallisationskinetik) untersucht. Schmelz‐ und Kristallisationstemperaturen ändern sich nur wenig als Funktion der Komponentenzusammensetzung; auch die Überstruktur ist nahezu invariant gegenüber der Konzentration des zugemischten TOR. Die aus den Verlustmodulmaxima der Torsionsschwingungskurven bestimmten Glastemperaturen zeigen jedoch interessante Abhängigkeiten. Durch Berechnung der Schiefe der G″‐(T)‐Maxima wird gezeigt, daß iPP‐Moleküle in die TOR‐Komponente diffundieren, in geringerem Maße auch TOR‐Moleküle in die iPP‐Matrix. Dadurch bildet sich ein Grenzschichtvolumen, in dem beide Komponenten lokal gemischt sind. Dieses Grenzschichtvolumen ist verantwortlich für den gemessenen erhöhten Anteil der heterogenen Keimbildung.
Antioxidants and stabilizers, 117. Contribution to the transformation mechanism of 2,6‐di‐tert‐butyl‐4‐methylphenol, a processing stabilizer for polyolefins
Authors: Pilař Jan , Rotschová Jitka , Pospíšil Jan 
Published: April 2003

Abstract2,6‐Di‐tert‐butyl‐4‐methylphenol (1), a polyolefin processing stabilizer, is transformed during the stabilization process primarily into 2,6‐di‐tert‐butyl‐4‐methyl‐phenoxyl (2). The important consecutive transformation pathway of 2 involves irreversible CC coupling giving 4,4′‐ethylenebis(2,6‐di‐tert‐butylphenol) (8) and reversible CC coupling accounting for formation of 2,6‐di‐tert‐butyl‐4‐methyl‐4‐(3,5‐di‐tert‐butyl‐4‐hydroxybenzyl)‐2,5‐cyclohexadiene‐1‐one (9). The stepwise transformation of 9 into the parent phenol 1, the stable dimer 8 and a variety of other products was found in EPR and chromatographic studies of free radical and molecular products generated from 9 in oxidative environment. It follows that compounds 1, 8 and 9 are stepwise transformed into coloured quinoide and quinonemethinoide compounds in the ultimate phase, and the antioxidant chain‐breaking character of 1 is thus lost. It is considered that most of the free radical species formed transiently during transformation of 1 and/or of derived phenolic coupling products disappear from the system via disproportionation and alkylperoxy radicals (RO2) or oxygen trapping. Labile, cross‐conjugated, peroxidic species generated by the latter process contribute to the fragmentation of coupling products.
Synthesis of polyacrylamide flocculants with poly(ethylene glycol) segments by redox polymerization
Authors: Erciyes A. Tuncer , Erim Melek , Hazer Baki , Yagci Yusuf 
Published: April 2003

AbstractThe polymerization of acrylamide (AAm) initiated by polyazoesters (PAE) possessing poly(ethylene glycol) (PEG) segments and azo functions was investigated in aqueous solution at 70°C. Polymerization of AAm initiated by PAE yields polymers with PEG segments and appropriate hydroxy functions for the subsequent redox polymerization. Polymerization of AAm induced by these polymers in conjunction with Ce(IV) provided increase in the molecular weight of the initial polymer without formation of insoluble polymer. The water‐soluble polymers obtained at various stages were tested in the flocculation of suspension of tincal concentrate and showed good flocculating properties.
Preparation of modified styrene‐divinylbenzene copolymers having different physical structures and their adsorption characteristics of nonionic surfactants
Authors: Fujita Itsusei , Nagano Yuko , Harada Kumiko , Nakayama Morio , Sugii Atsushi 
Published: April 2003

AbstractSeveral α‐oxoethylated and α‐hydroxyethylated styrene‐divinylbenzene (St‐DVB) resins having different degrees of crosslinking and porosity were prepared and their adsorption behaviour toward a nonionic surfactant, decaethyleneglycol nonylphenyl monoether, was investigated. The increment of the adsorption capacity caused by the introduction of the α‐hydroxyethyl groups was remarkable in the less crosslinked resin. The α‐hydroxyethylated resin derived from the St‐DVB resin synthesized with 10 vol.‐% DVB and 100 – 120 vol.‐% of 2,2,4‐trimethylpentane showed the highest capacity among the resins tested. The significance of both macroporosity and gel porosity in the effective adsorption of the nonionic surfactant was elucidated. A column operation using proposed resins was carried out and versatility was evaluated in terms of the breakthrough capacity.
Fracture mechanics analysis of rubber‐modified polyamide‐6: Temperature and rate effect with varying rubber content
Authors: Ricco Theonis , Pavan Andrea 
Published: April 2003

AbstractElasto‐plastic fracture mechanics has been applied to a series of EPDM‐modified polyamide‐6 samples with varying rubber content, in order to characterize properly their fracture behaviour. J‐testing has been carried out to determine the J‐resistance (JR) curve and to evaluate therefrom the fracture initiation resistance, JIC, and the fracture propagation parameter dJ/da. The results obtained are analyzed and discussed as a function of rubber content, temperature, and strain rate.
Relations between physical parameters and kinetics of photo‐induced radical polymerization in polymer binders: Radical polymerization of acrylamide
Authors: Timpe Hans‐Joachim , Müller Franz Werner , Strehmel Bernd , Panzner Gerit , Schiller Kurt , Reuter Hardy 
Published: April 2003

AbstractThe photo‐induced radical polymerization of acrylamide has been investigated in combinations of two polymers containing carboxy groups. The kinetic parameters of this polymerization, measured with a calorimetric method, depend on the proportion of the two polymers in the system. In mixtures with the lowest glass transition temperature, the polymerization rates are the highest. These transition temperatures have been determined with a special fluorescene technique using crystal violet as probe. Presumably, the effects measured in the systems are based on the strong polar interactions between the carboxy groups of both polymers.
Molecular aspects of rubberlike elasticity
Authors: Mark J. E. 
Published: April 2003

AbstractMolecular theories of rubberlike elasticity are surveyed, starting with the earliest attempts carried out in the 1930's and ending with work still very much in progress. The models are variously based on phenomenological arguments, affinely‐deforming networks, phantom networks, constrained junctions, constrained chains, slip‐links, molecular tubes, van der Waals concepts, or rotational isomeric chains. Most of the theories are analytical, but some involve computer simulations based on Monte Carlo methods. The theories are generally for networks of Gaussian chains, but there have been significant advances for non‐Gaussian networks as well, and these are particularly important with regard to a better understanding of ultimate properties. The major outstanding problem on the theory side, however, seems to be a quantitative treatment of chain entanglements.There have also been numerous advances on the experimental side. These include preparation of model networks of known structure, accumulation of elasticity data for deformations other than the much‐studied simple elongation, development of new characterization techniques (such as fluorescence polarization, and X‐ray and neutron scattering), investigation of the phenomenon of gel collapse, borrowing of ideas from the area of bioelastomers, and preparation of novel reinforcing fillers.
From two‐dimensional model networks to microcapsules
Authors: Burger Andreas , Rehage Heinz 
Published: April 2003

AbstractThe 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

AbstractSemi‐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

AbstractSulfur 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

AbstractTodays 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

AbstractIn 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

AbstractHNBR 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

AbstractThermotropic 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.