bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of fluorene‐bisphenol ring substitution and bridge rigidity on physical and gas permeation properties of resulting polyarylates
Authors: Bhole YS , Kharul UK 
Published: September 2003

AbstractThis study reveals gas permeability and related physical properties of aromatic polyesters prepared from fluorenone‐based bisphenols and an equimolar mixture of isophthalic and terephthalic acids. Effects of a rigid bridge group at these bisphenols were examined. Bisphenol phenyl rings were also substituted in an asymmetric substitution manner (the two positions ortho to —OH contained different groups) in dimethylfluorene bisphenol (DMFBP) and dibromodimethylfluorene bisphenol (DBrDMFBP). Polyarylates prepared using these bisphenols were studied for gas permeation with reference to the effects of bridge rigidity and asymmetric substitution by polar bromine and non‐polar methyl groups. Glass transition temperature and estimated fractional free volume were varied by incorporation of rigid 9,9′‐fluorenylidene group. An increase in gas permeability was associated with a similar or general decrease in selectivity of various gas pairs. This behaviour was attributed mainly to the rigid but flat group situated at the bridge position of the bisphenol moiety. Copyright © 2003 Society of Chemical Industry
Investigation of compatibility of a dicyanate ester monomer and polysulfone by size‐exclusion chromatography and viscometry
Authors: Gómez Clara M , Porcar Iolanda , Recalde Ileana , Campos Agustín 
Published: September 2003

AbstractThe influence of solvent on the compatibility behaviour of Arocy B10, a cyanate ester monomer, and polysulfone (PSF) was investigated by means of dilute solution viscometry and of the preferential solvation parameter at 25 °C. The ternary systems under study are: tetrahydrofuran/Arocy B10/polysulfone (PSF), N,N‐dimethylformamide/Arocy B10/PSF and dichloromethane/Arocy B10/PSF. Values of the specific viscosity of PSF in a ‘binary solvent’ formed by Arocy B10 + solvent have been used to determine the compatibility of the polymer blend Arocy B10/PSF. An interaction parameter Δb that depends on concentration has been determined. The preferential solvation parameter was measured by size‐exclusion chromatography at different monomer‐to‐polymer ratios. PSF was found to be preferentially solvated by the monomer. Both techniques agree quantitatively in every system indicating maximum compatibility at the same Arocy B10 concentration. However, they differ when comparing the two parameters among the three systems. Copyright © 2003 Society of Chemical Industry
Synthesis and characterization of novel diimide–dinaphthols and resulting poly(urethane–imide)s
Authors: Mehdipour‐Ataei Shahram , Keshavarz Shahriar 
Published: September 2003

AbstractNovel diols containing imide groups were prepared via condensation of aromatic dianhydrides with 5‐amino‐1‐naphthol. The diimide–dinaphthols prepared were characterized by conventional methods and used to synthesize new poly(urethane–imide)s (PUIs). All the polymers were characterized and their physical properties, such as solubility, solution viscosity, thermal stability, and thermal behaviour were studied. The polymers obtained showed more thermal stability than typical polyurethanes because of the presence of the imide groups. Copyright © 2003 Society of Chemical Industry
Synthesis and properties of novel poly(meth)‐acrylates containing tricyanocyclopropyl groups for piezoelectric applications
Authors: Lee Ju‐Yeon , Bang Han‐Bae , Choe Sang Joon 
Published: September 2003

Abstracto‐(2,2,3‐Tricyano‐3‐carbomethoxycyclopropyl)phenoxyethyl acrylate (5a) and o‐(2,2,3‐tricyano‐3‐carbomethoxycyclopropyl)phenoxyethyl methacrylate (5b) were prepared by reactions of bromomalononitrile with methyl o‐(2‐acryloyloxyethoxy)benzylidenecyanoacetate and methyl o‐(2‐methacryloyloxyethoxy)benzylidenecyanoacetate respectively. The dipole moments of 5a and 5b, calculated by atom superposition and electron delocalization molecular orbital method, were 2.75–3.47 D. Monomers 5a and 5b were polymerized with free‐radical initiators to obtain the polymers with tricyanocyclopropane ring as a piezoelectric chromophore in the pendant group. The resulting polymers 6a and 6b were soluble in common organic solvents such as acetone and DMF. Polymers 6a and b showed thermal stability up to 280 °C in TGA thermograms. Tg values obtained from DSC thermograms were in the range 125–140 °C. Piezoelectric coefficients (d31) of the poled films were 1.2–1.4 pC N−1. These polymers showed good temporal and long‐term thermal stabilities which are acceptable for piezoelectric device applications. Copyright © 2003 Society of Chemical Industry
Hydrophilisation of silicone rubber for medical applications
Authors: Hron Petr 
Published: September 2003

AbstractSilicone rubber is one of the biomaterials used for preparation of medical implants. The properties of silicone rubber and methods of their evaluation are surveyed with respect to the medical applications. For some applications the hydrophobic character of silicone rubber is undesirable and possibilities of its hydrophilisation are presented in this review as well. Special attention is paid to the process of preparation of hydrophilic silicone rubber–hydrogel composite materials based on acrylic and methacrylic acids derivatives and to the properties of such materials. Copyright © 2003 Society of Chemical Industry
Studies on polybenzimidazole/poly (4‐vinylpyridine) blends and their proton conductivity after doping with acid
Authors: Pu Hongting 
Published: September 2003

AbstractIn the present work, polybenzimidazole (PBI) and poly(4‐vinylpyridine) (P4VP) were chosen because they form miscible blends and both materials are suitable for acid doping as a matrix, which can eventually be used as proton conductor. The miscibility and inter‐polymer interactions were studied by infrared (IR) spectroscopy and differential scanning calorimetry (DSC). DSC and IR results suggest that PBI blended with P4VP exhibits good miscibility due to the strong hydrogen bonds formed between PBI's NH groups and P4VP's N: groups. The glass transition temperatures of the blends can be fitted to the Fox equation very well. The blends were also studied by thermogravimetry. Their thermal stability is slightly higher than that of P4VP, but is still lower than that of PBI. Temperature‐dependent conductivity of acid‐doped PBI/P4VP blends was studied. As the temperature increases, the conductivity of PBI/P4VP doped with H3PO4 increases. The temperature‐dependent conductivity of the blends follows a simple Arrhenius relationship when the P4VP content is low (less than 15%), while a non‐Arrhenius behaviour of the conductivity of the blends becomes more and more significant with increasing P4VP content. This means that the proton transport in the blends is controlled by both a hopping mechanism and the segmental motion of the polymer. The contribution of these two mechanisms depends on the P4VP content. Copyright © 2003 Society of Chemical Industry
Synthesis of linear low density polyethylene (LLDPE) by in situ copolymerization with novel cobalt and zirconium catalysts
Authors: Wang Hang , Ma Zhi , Ke Yucai , Hu Youliang 
Published: September 2003

AbstractNew cobalt catalysts {[2,6‐(CH3C=NAr)2C5H3N]CoCl2} (Ar=2‐methyl‐4‐methoxyphenyl, 1) and (Ar=2,4‐dimethylphenyl,2) were synthesized and found to exhibit good selectivity for α‐olefins with methylaluminoxane (MAO) as co‐catalyst. With only ethylene as the feed monomer cobalt catalysts 1 or 2 can be coupled with zirconium catalyst Dichloro [rac‐ethylenebis(indenyl)]Zirconium (IV) rac‐EtInd2ZrCl2 (3) to produce linear low density polyethylene by in situ polymerization. Spectra of resulting materials exhibit ethyl, butyl and long‐chain branches in the backbone of polyethylene. The ratio of Co/Zr and Δt, which is defined as the interval between introductions of two catalysts into the reactor, influenced catalytic activity and the resulting materials greatly. Compatibility and complementary behaviour of different catalysts proved to be two most important factors for in situ copolymerization. Copyright © 2003 Society of Chemical Industry
Connection of surface tension with multiple tribological properties in epoxy + fluoropolymer systems
Authors: Brostow Witold , Cassidy Patrick E , Macossay Javier , Pietkiewicz Dorota , Venumbaka Sreenu 
Published: September 2003

AbstractContact angles of free liquids on solid samples were measured and the van Oss–Good method was applied for evaluating surface tensions of the solids. A parachor method was used for comparison: in this case the respective values were calculated for the polymer solids from molecular and group contributions. Surface tensions were computed from the parachors and the two methods compared. Effects of varying the fluoropolymer added to the epoxy before curing are discussed. For a given fluoropolymer, effects of changing its concentration on surface tension have also been evaluated and compared to the changes in scratch resistance (scratch penetration depth, recovery depth) and in static and dynamic friction. Morphological and phase structure changes are reflected in all these properties, showing a strong connection between the surface tension and tribological properties. Copyright © 2003 Society of Chemical Industry
Intumescent char structures and flame‐retardant mechanism of expandable graphite‐based halogen‐free flame‐retardant linear low density polyethylene blends
Authors: Qu Baojun , Xie Rongcai 
Published: September 2003

AbstractThe structures of the intumescent charred layers formed from expandable graphite (EG)‐based intumescent halogen‐free flame retardant (HFFR) linear low‐density polyethylene (LLDPE) blends and their flame‐retardant mechanism in the condensed phase have been studied by dynamic Fourier transform infrared (FTIR), X‐ray photoelectron spectroscopy (XPS), laser Raman spectroscopy (LRS), scanning electron microscopy (SEM), differential thermal analysis (DTA) and thermal conductivity (TC) measurements. The dynamic FTIR, XPS and LRS data show that the carbonaceous structures of intumescent charred layers consist of EG and various numbers of condensed benzene rings and/or phosphocarbonaceous complexes attached by the POC and PN bonds or quaternary nitrogen products. The addition of EG can hasten the formation of these phosphocarbonaceous structures. The above results show that the flame‐retardant mechanism in the condensed phase is that the compact char structures, as observed by SEM, slow down heat and mass transfer between the gas and condensed phase and prevent the underlying polymeric substrate from further attack by heat flux in a flame. The DTA and TC data show that carbonaceous charred layers are good heat‐insulating materials, the TC value of which is only about one‐tenth of that of the corresponding blend and that they increase the oxidization temperature and decrease thermal oxidization heat of the LLDPE/EG/HFFR systems.© 2003 Society of Chemical Industry
Abgehoben: Schweben in elektromagnetischen Feldern
Authors: Voigt Felix , Hinsch Klaus 
Published: September 2003

AbstractStatisches, stabiles, freies Schweben ist in elektrostatischen oder magnetostatischen Feldern unmöglich. Trotzdem gibt es verschiedene Möglichkeiten, Körper mit elektromagnetischen Feldern schweben zu lassen. Eine Möglichkeit bieten aktive regelungstechnische Steuerungen. Noch geschickter sind Spulenanordnungen, die den schwebenden Körper mit harmonischen Wechselfeldern in einer zentralen Gleichgewichtslage halten.
Das Erdmagnetfeld — Beobachtung und Überwachung: SPEZIAL: GEOPHYSIK
Authors: Haak Volker , Maus Stefan , Korte Monika , Lühr Hermann 
Published: September 2003

AbstractDas Erdmagnetfeld umgibt unseren Planeten wie ein unsichtbarer Schutzschild. Nachweisen lässt es sich leicht mit einem Kompass. In den letzten Jahrzehnten wurde aber immer deutlicher, dass das Erdmagnetfeld aus vielen Quellen gespeist wird. Nach unserem gegenwärtigen Wissen setzt es sich aus sieben Komponenten zusammen. Mit modernen Methoden ist es mittlerweile möglich, selbst schwächste Beiträge beispielsweise von der Lithosphäre oder von den ozeanischen Gezeitenströmungen zu messen.
Kollidierende Kontinente: SPEZIAL: GEOPHYSIK
Authors: Kind Rainer , Yuan Xiaohui 
Published: September 2003

AbstractMit einer neuen seismologischen Methode, die natürliche Quellen seismischer Energie benutzt, ist es gelungen, Strukturen in der gesamten Lithosphäre und im oberen Erdmantel von Tibet abzubilden. Deren Interpretation ermöglicht es, die geologische Geschichte der Kollision des indischen Subkontinentes mit dem eurasischen Kontinent aufzuklären.
Das Märchen vom Zauberer im weißen Kittel: Mythen um berühmte Experimente und Experimentatoren
Authors: Hentschel Klaus 
Published: September 2003

AbstractUm berühmte Experimentatoren und Experimente ranken sich ebenso Mythen wie um geniale Theoretiker. Sie sind in populärwissenschaftlichen Büchern, Lehrbüchern und sogar in wissenschaftshistorischen Texten verbreitet. Die durch die Aufklärung etablierte Kultur des eleganten Schauexperiments vermittelt ein schiefes Bild vom mühsamen Weg vieler Experimentatoren zum dargestellten Ergebnis. Auch der Mythos des einsamen, genialen Experimentators ohne Helfer widerspricht dem historischen Befund. Gleiches gilt für dasexperimentum crucis, das eine Theorie als entscheidendes Experiment belegen soll. Die historische Forschung zeigt, dass es eine lange, eigenständige Tradition der experimentellen und instrumentellen Arbeit gibt.
Das Schwerefeld der Erde: SPEZIAL: GEOPHYSIK
Authors: Reigber Christoph , Schwintzer Peter 
Published: September 2003

AbstractDie Kenntnis des Schwerefelds der Erde erlaubt Einblicke in die Struktur und Dynamik des Erdinnern und ermöglicht das Studium von an der Erdoberfläche ablaufenden Prozessen. Sie liefert mit dem Geoid eine wichtige physikalische Bezugsfläche in der Geodäsie und Ozeanographie. Der im Gravitationsfeld der Erde fliegende Satellit CHAMP misst derzeit die Globalstruktur des Schwerefelds mit bisher unerreichter Genauigkeit. Mit der 2002 gestarteten Mission GRACE und der geplanten GOCE steht das Erdschwerefeld gegenwärtig im Zentrum des geowissenschaftlichen Interesses.
Extrem dichtes Plasma im Festkörper
Authors: Glenzer Siegfried 
Published: September 2003

AbstractAm Lawrence Livermore National Laboratory (LLNL), USA, ist es gelungen, für kurze Zeit im Innern eines Festkörpers ein extrem dichtes Plasma zu erzeugen. Mit Hilfe von Röntgenstreuung konnten zudem Temperatur und Dichte mit guter Genauigkeit gemessen werden [1].
Die Sonne bringt es an den Tag
Authors: Ziegler Thomas 
Published: September 2003

AbstractDie Neutrinoforschung macht weitere Fortschritte. Mit dem Sudbury Neutrino Observatory ließ sich die Oszillation von solaren Neutrinos stichhaltig belegen, und in Japan gelang es, Neutrinos aus Kernreaktoren nachzuweisen. Die Messwerte aller bisherigen Neutrinoexperimente ermöglichten es jetzt auch, den Anteil des CNO‐Zyklus an der Energieerzeugung im Innern der Sonne einzugrenzen.
Flüssige Mikroschalter
Authors: Drach Volker 
Published: September 2003

AbstractDas nichtlineare Verhalten viskoelastischer Flüssigkeiten hat außergewöhnliche strömungsmechanische Effekte zur Folge. Diese lassen sich zum Bau von Schaltelementen ausnutzen, die jenen der Mikroelektronik ähneln. So realisierten jüngst Alex Groisman und Kollegen am California Institute of Technology die Funktion eines Fluss‐Stabilisators und eines Flip‐Flop‐Speichers zur Kontrolle mikroskopischer Strömung [1].
Optisch erzeugte Spinströme
Authors: Hübner Jens 
Published: September 2003

AbstractDurch Absorption von zwei Laserstrahlen mit unterschiedlichen Wellenlängen können in Halbleitern makroskopische Ströme erzeugt werden. Die Ausbreitungsrichtung der Elektronen und insbesondere die Ausrichtung ihrer Spins lassen sich über die relative Phase der beiden Laserfelder kohärent kontrollieren, wie kürzlich zwei Gruppen an den Universitäten von Marburg und Iowa demonstrierten [1, 2]. Genutzt wird bei diesem Experiment der Effekt der Quanteninterferenz zur Erzeugung von elektrischen Spinströmen.
Die Anfänge des Physik‐Nobelpreises
Authors: Jacobi Manfred 
Published: September 2003

AbstractKeine andere Auszeichnung in den Naturwissenschaften erfährt so viel Aufmerksamkeit wie der Nobelpreis. Viele Geehrte werden untrennbar mit der Kulturgeschichte der Menschheit verbunden bleiben, andere werden vergessen. Von der nächsten Ausgabe an werden wir nicht nur wie gewohnt im letzten Heft des Jahres die aktuellen Physik‐Nobelpreisträger und ihre Entdeckung vorstellen, sondern gleichzeitig einen Blick hundert Jahre zurück werfen. Damit der Anfang nicht fehlt, stellen wir Ihnen hier die Preisträger vor.
Das streitlustige Akademiemitglied
Authors: Loos Andreas 
Published: September 2003

AbstractDie Erde ist keine Kugel, sondern ein mehr oder minder verknautschter Ellipsoid. Vor 250 Jahren ruhte der Zweifel an der perfekten Kugelgestalt dagegen nur auf vagen Vermutungen und Theorien — und war heftig umstritten.
Käse ist Physik
Authors: Vilgis Thomas A. 
Published: September 2003

AbstractAuf den ersten Blick scheinen Physik und Kochen wenig miteinander zu tun zu haben. Dass in der Küche dennoch interessante physikalische Vorgänge ablaufen, erklärt uns Thomas Vilgis in der neuen Kolumne Mol‐Gastronomie.
Manufacturers' compliance with the US Food and Drug Administration's Over‐the‐counter Human Drugs: Labeling Requirements
Authors: Sansgiry Sujit S. , Shringarpure Gauri 
Published: September 2003

AbstractThe use of over‐the‐counter (OTC) medications is increasing every year among consumers for symptomatic relief of ailments. Consumers have difficulties in reading and comprehending information on the OTC medication packages. A standardized format to present information on OTC medication packages was necessary; hence the FDA announced guidelines, Over‐the‐counter Human Drugs: Labeling Requirements, on 11 March 1999. Manufacturers have been given 6 years since 1999 to comply with the FDA guidelines. The objective of our study was to evaluate marketed OTC medication packages to determine the extent of adoption of the FDA guidelines by manufacturers. Packages (n ± 104) of OTC medication products from three different categories, viz. pain relievers, cough and cold remedies and stomach remedies, were evaluated for general information, written information and product claims. The Compugraphic point system scale was used to measure the font size of written information. In addition variables recommended by the FDA, such as bullets, paragraphs and hyphenations, were also evaluated. All the variables were coded in a database and analysed using the SAS (Version 8.2) statistical package. The study found that some manufacturers have adopted the FDA guidelines. However, many manufacturers did not implement several aspects of the guidelines. Although manufacturers still have a few more years to adhere to the guidelines, early implementation could benefit the consumers. Copyright © 2003 John Wiley & Sons, Ltd.
Wide‐spectrum antimicrobial packaging materials incorporating nisin and chitosan in the coating
Authors: Lee Chan Ho , An Duck Soon , Park Hyun Jin , Lee Dong Sun 
Published: September 2003

AbstractNisin and/or chitosan were coated, in 3% concentrations, onto paper with a binder medium of vinyl acetate–ethylene co‐polymer to provide antimicrobial activity for use in food packaging. The combined use of nisin and chitosan in the coating was an attempt to give a wide antimicrobial spectrum that could inhibit the growth of several food spoilage and poisonous microorganisms. The migration of the preservative from the coatings to water was evaluated at 10°C and related to the suppressed microbial growth in the water and microbial medium. After 8 days, 8.1–8.3% of nisin and 1.0–1.2% of chitosan had migrated, and the migration of each was not affected by the presence of the other. The paper coated with nisin was more effective than the chitosan‐coated paper in inhibiting the Gram‐positive bacterium, Listeria monocytogenes, whereas the latter was more effective against Escherichia coli O157:H7. Combined inclusion of nisin and chitosan in the coating gave antimicrobial activity against both bacterial strains, and could improve the microbial stability of milk and orange juice stored at 10°C. Copyright © 2003 John Wiley & Sons, Ltd.
Application of a computer model to evaluate the ability of plastics to act as functional barriers
Authors: Han Jong‐Koo , Selke Susan E. , Downes Theron W. , Harte Bruce R. 
Published: September 2003

AbstractA simulation model computer program, which accounts for not only the diffusion process inside the polymer but also partitioning of the contaminant between the polymer and the contacting phase, was developed based on a numerical treatment, the finite element method, to quantify migration through multilayer structures. The accuracy of the model in predicting migration was demonstrated successfully by comparing simulated results to experimental data. For this study, three‐layer co‐extruded high density polyethylene (HDPE) film samples, having a symmetrical structure with a contaminated core layer and virgin outer layers as the functional barriers, were fabricated with varying thickness of the outer layers and with a known amount of selected contaminant simulant, 3,5‐di‐t‐butyl‐4‐hydroxytoluene (BHT), in the core layer. Migration of the contaminant simulant from the core layer to the liquid food simulants was determined experimentally as a function of the thickness of the outer layer at different temperatures. The computer program, developed as a total solution package for migration problems, can be applied not only to multilayer structures made with the same type of plastics but also to structures with different plastics, e.g. PP/PE/PP. This work might provide the potential for wider use of recycled plastic, especially polyolefins, which have lower barrier properties, in food packaging, and simplification of the task of convincing the FDA that adequate safety guarantees have been provided. Copyright © 2003 John Wiley & Sons, Ltd.
Package performance testing of dangerous goods in high‐altitude shipments
Authors: Singh S. Paul , Burgess Gary J. , Singh Jagjit 
Published: September 2003

AbstractThis paper discusses the impact of high‐altitude shipments on package integrity. High‐altitude shipments are encountered when trucks travel over high mountain passes or when cargo and feeder aircraft transport packages in non‐pressurized or partially‐pressurized cargo holds. Both these types of transport methods will result in severe changes in pressure as compared to packages being transported close to sea level. The testing of packages under these conditions is critical since package integrity may be compromised. The current shipping tests performed in test laboratories do not account for pressure changes and vibration together. This study showed that combination packages for dangerous goods and hazardous materials that are tested to existing UN, ICAO and US DOT requirements are limited, and can result in significant number of leaks. Testing under combined vibration and pressure changes is necessary. Copyright © 2003 John Wiley & Sons, Ltd.