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  • 1
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Im Temperaturbereich von 60 bis 100°C wird die radikalische Polymerisation von Styrol, Methylmethacrylat und Acrylnitril von α.α′-Dicyanodibenzylen ausgelöst, die in α-und α′-Stellung mit Ester-, Nitril-, Amid- oder Phenylgruppen disubstituiert sind. Bei 100 bis 110°C ist auch das α.α.α′.α′-Tetracarboxymethyldibenzyl aktiv. Vinylacetat und Vinylchlorid werden durch diese Initiatoren kaum polymerisiert.Fur die Polymerisation des Styrols wurden die Bruttogeschwindigkeitskonstanten Kp, für viele Dibenzyle und fur Peroxide vergleichbarer Aktivitat dilatornetrisch bestirnrnt. Norrnalerweise sind die Zeit-Urnsatz-Kurven rnit den Dibenzylen und den Peroxiden vergleichbar; das Tetracyanodibenzyl allerdings bewirkt nur eine unvollstandige Polymerisation.Der große Einfiuß von Substituenten in α-Stellung oder in den Phenylringen der Dibenzyle auf die Polymerisation des Styrols wird diskutiert. Dabei ist auch die Stereochernie wichtig. Die meso-Form des Dinitrildiesters ergibt eine 2.5- bis 3.5 ma1 schnellere Polyrnerisation als das dl-Isornere.Die Dissoziationsgeschwindigkeitskonstanten kd der Initiatoren wurden NMR-spektroskopisch aus der Linienbreite bestirnmt. Die Dinitrildiester sind gute Initiatoren, wahrend die α.α′-Dicyanodibenzyle rnit weiteren Nitril- oder Phenylgruppen in α- und α′-Stellung wenig geeignet sind. SchlieBlich wurde die 1.2-Addition einiger der Dibenzyle an Styrol im Ternperaturbereich von 120 bis 150°C rnit der Methode der chernisch induzierten KernPolarisation (CIDNP) untersucht.
    Notes: The radical polymerization of styrene, methyl methacrylate and acrylonitrile is initiated by α.α′-dicyanodibenzyls α.α′-disubstituted with ester, nitrile, amide or phenyl groups in the temperature range 60 to 100°C and by α.α.α′.α′-tetracarboxymethyldibenzyl at 100 to 110°C. Vinylacetate and vinylchloride show a low reactivity.The overall polymerization rate constants Kp have been determined dilatometrically for styrene initiated by a large number of dibenzyls and comparable peroxides. The styrene polymerization curves are generally comparable with those of peroxides. A notable exception is tetracyanodibenzyl.The strong influence of α- and ring-substituents in the dibenzyls on the styrene polymerization rate is discussed. The stereochemistry is also important : the meso α.α′-dicyanodibenzyls α.α′-disubstituted with ester groups give a 2.5 to 3.5 fold faster polymerization than their dl isomers.The initiator efficiency is related to the kd values, determined from NMR line width measurements. The α.α′- dicyanodibenzyls α.α′-disubstituted with ester groups are good initiators, while those with phenyl groups and nitrile groups are inefficient.Relevant to initiation and termination, the 1.2-addition of some of the dimers to styrene at 120 to 150°C has been studied with chemically induced dynamic nuclear polarization (CIDNP).
    Additional Material: 7 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 24 (1990), S. 829-845 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This article describes the histological and ultrastructural appearance of the interface created in the implantation bed, between bone tissue and implants made of dense sintered hydroxyapatite (HA). Biopsies from dog subjects included: (a) loaded permucosal dental implants for tooth substitution, (b) subperiosteally placed implants for alveolar bone correction, (c) endosseously placed dental root implants to retain ridge form following extraction. The light and electron microscopical results show extensive bone apposition on the osseous sides of the implant surfaces. There is an intimate, direct bone contact without any visible interruption. The bone is of normal lamellar type and continuously connected with the trabecular bone. Bone has grown into the finest surface irregularities of the implant. Collagen fibers of the calcified bone matrix are observed within a distance less than 500 Å from the implant surface. The thin (20-100 Å) electron dense layer at the bone-implant interface resembled the lamina limitans of organic bone matrix, also seen at the inner walls of the osteocytes lacunes. Deposition of bone gives rise to a biologically stable bone-implant interface, without disturbance of the physiological bone turnover. This is seen as very favorable for desired long term fixation of implant to bone.
    Additional Material: 17 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Advanced Materials 7 (1995), S. 148-151 
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 2 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 54 (1976), S. 187-201 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Moderne instrumentelle Methoden wurden zur Analyse von Harnstoff-Formaldehyd-Harzen verwendet. Ein ausführliches Studium der Silylierung des Harzes mittels BSTFA (N,O-Bistrimethylsilyltrifluoracetamid) ermöglicht die quantitative gaschromatographische Bestimmung der niedermolekularen Verbindungen Harnstoff, Monomethylolharnstoff und Dimethylolharnstoff. Das Verhältnis zwischen nieder- und hochmolekularen Verbindungen sowie die Mengen an niedermolekularen Verbindungen können mittels GPC-Analyse auf Sephadex LH 20 in Wasser ermittelt werden.Ein vollständiges Bild des Harzes erhält man durch 220 MHz 1H-NMR-Analyse von Lösungen von gefriergetrockneten Proben in DMSO-d6. Zusammen mit den Ergebnissen klassischer chemischer Analysen ergeben die Resultate der drei genannten Techniken einen guten Überblick über den Aufbau eines Harnstoff-Formaldehyd-Harzes.
    Notes: Modern instrumental techniques were used for analysing water-based urea-formaldehyde resins. An exhaustive study was made of the silylation of such a resin with BSTFA (N,O-bistrimethylsilyltrifluoroacetamide). From the gas chromatograms the amounts of urea, monomethylol urea and dimethylol urea can be determined quantitatively, thus giving information on the low molecular weight part of the resin. The ratio of low to high molecular weight components as well as the amounts of several low molecular weight compounds can be estimated from a GPC analysis on Sephadex LH 20 in water. A detailed picture of the resin is obtained when freeze-dried samples are subjected to 220 MHz 1H-NMR analysis in DMSO-d6.An overall insight into the composition of these resins can be gained when the results of the mentioned techniques are combined with those of classical chemical analyses.
    Additional Material: 13 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 111 (1983), S. 17-27 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aromatische Polyamide mit Imidseitengruppen wurden aus 4,4′-Diaminodiphenylether und Imid-Disäurechloriden durch Lösungspolykondensation hergestellt. Die verwendeten Imid-Disäurechloride umfaßten die Disäurechloride von 5-Maleinimidoisophthalsäure, 5-Dichlormaleinimidoisophthalsäure, 5-Tetrahydrophthalimidoisophthalsäure, 5-Hexachlorendomethylentetrahydrophthalimidoisophthalsäure, 5-Endomethylentetrahydrophthalimidoisophthalsäure, 5-Methylenendomethylentetrahydrophthalimidoisophthalsäure, und 5-Phthalimidoisophthalsäure. Das reine aromatische Polyamid aus 4,4′-Diaminodiphenylether und Isophthaloylchlorid wurde zu Vergleichszwecken ebenfalls hergestellt.Polyamidimide sind in polaren organischen Lösungsmitteln löslich und zeigen gute thermische Beständigkeit. Sie können Filme bilden, die gute mechanische Eigenschaften haben. Diejenigen Polyamidimide, die ungesättigte Kohlenstoff-Kohlenstoff-Bindungen enthalten, können durch Erhitzen auf 220°C vernetzen und geben unlösliche Materialien mit verbesserter mechanischer Festigkeit.
    Notes: Aromatic polyamides with imide pendent groups were prepared from 4,4′-diaminodiphenylether and imide-diacid chlorides by solution polycondensation. Imidediacid chlorides used included the diacid chlorides of 5-maleimidoisophthalic, 5-dichloromaleimidoisophthalic, 5-tetrahydrophthalimidoisophthalic, 5-chlorendimidoisophthalic, 5-nadimidoisophthalic, 5-methylnadimidoisophthalic and 5-phthalimidoisophthalic acid. The pure aromatic polyamide from 4,4′-diaminodiphenylether and isophthaloyl chloride was also prepared for comparative reasons.Polyamide-imides are soluble in polar organic solvents and show good thermal resistance. They are film-forming and the films have good mechanical properties. Those polyamide-imides which contain unsaturated carbon-carbon bonds may be crosslinked by heating to 220°C, giving rise to insoluble materials with improved mechanical resistance.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 239 (1996), S. 33-41 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der neuartige dikationische Komplex [dppfNi(MeCN)4][BF4]2 (dppf = 1,1′-Bis(diphenylphosphin)ferrocen) zeigte in Anwesenheit von Diethylaluminiumchlorid (AIEt2CI) hohe Aktivität für die Polymerisation von 1,3-Butadien. Reaktionsdauer, Temperatur und das Aluminium/Nickel-Verhältnis wurden auf maximale Aktivität und Selektivität optimiert. Umsätze über 90% konnten erreicht werden. Im Vergleich zu Polybutadienen, die mit anderen Nickel-Phosphin-Systemen hergestellt wurden, zeigten die synthetisierten Polybutadiene höhere cis-1,4-Anteile (〈80%) und eine geringe Bildung von 1,2-Einheiten (2%). Alle Polymeren hatten niedrige mittlere Molekulargewichte (Mw 〉 11 800).
    Notes: The new dicationic nickel complex [dppfNi(MeCN)4][BF4]2 (dppf = 1,1′-bis(diphenylphosphino)ferrocene) in the presence of diethylaluminium chloride (AIEt2CI) exhibited high activity on the 1,3-butadiene polymerization. Reaction time, temperature and aluminium/nickel molar ratio were optimized in order to achieve maximum activity and selectivity. Conversions higher than 90% were obtained in contrast to other nickel-based systems using phosphine ligands, the resulting polybutadiene showed high cis-1,4 (〈80%) content and only small amount of 1,2-units (2%). All polymers presented low molecular weights (Mw 〉 11 800).
    Additional Material: 2 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 62 (1977), S. 7-31 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die 13C-NMR-Spektroskopie wurde zur Analyse von Formaldehyd-Harzen verwendet. Aus Phenolen, Harnstoff und Melamin wurden mit Formalin Harze hergestellt. Die chemischen Verschiebungen dieser Harze wurden relativ zu TMS gemessen. Alle Harze waren in DMSO-d6 löslich, so daß die Signale von unterschiedlichen Harzen verglichen werden konnten.Die Spektren wurden mit Hilfe der Spektren von Referenzsubstanzen und einfachen, auf Additivität basierenden Rechenregeln interpretiert. Jeder Harztyp hat sein eigenes spezifisches Spektrum und enthält Signale, die über die Struktur im Zusammenhang mit dem Katalysatortyp und der Kondensationsweise Auskunft erteilen. Die unterschiedlichen Formen, in denen Formaldehyd in diese Harze als Methylenkohlenstoff eingebaut ist, lassen sich unzweideutig aus dem Gebiet von 20 bis 100 ppm bestimmen.Diese Arbeit zeigt, daß sich die 13C-NMR Spektroskopie sehr gut für die Analyse von Formaldehydharzen eignet.
    Notes: 13C-NMR spectroscopy has been applied to the analysis of formaldehyde containing resins. Samples have been prepared from phenols, urea and melamine with formaldehyde. The chemical shifts of the carbon atoms in the resins were measured relative to TMS. All the samples could be dissolved in DMSO-d6 which facilitated the comparison of signals in different resins.The spectra were interpreted with the aid of spectra of reference compounds and simple calculations based on additivity increments. Each type of resin gives a specific 13C-NMR spectrum in which lines can be assigned that give information on the structure of the resin in relation to the type of condensation or catalyst used. Moreover, the different ways in which formaldehyde is incorporated in the resins as methylene carbon can be unambiguously determined from the region between 20 and 100 ppm.This work shows that 13C-NMR spectroscopy is a powerful tool for the analysis of formaldehyde containing resins.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 139 (1986), S. 113-122 
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Copolyamide mit Nadimidseitengruppen wurden durch Polykondensation von 5-(5-Norbornen-2,3-dicarboximido)-isophthaloylchlorid (NCIC) und Isophthaloylchlorid mit Bis(4-aminophenyl)-methan hergestellt, wobei die verwendeten Verhältnisse der beiden Dicarbonsäurechloride 0/100, 10/90, 15/85, 20/80, 25/75, 50/50 und 100/0 betrugen. Durch 1H-NMR Untersuchung wurde festgestellt, daß die Zusammensetzung der entstehenden Copolyamide mit der der ursprünglichen Monomermischungen übereinstimmte.Die Eigenschaften der Copolyamide, wie Löslichkeit, Glasübergangstemperatur und thermische Beständigkeit, wurden gemessen und bezüglich der Zusammensetzungen interpretiert. Die Vernetzung der Copolymeren wurde mittels DSC studiert und ein Vergleich ihrer Eigenschaften vor und nach der thermischen Vernetzung durchgeführt.Der Einfluß der Vernetzung auf die mechanischen Eigenschaften der Copolyamidfolien wurde ebenfalls gemessen.
    Notes: Copolyisophthalamides with nadimide pendent groups have been prepared by polycondensation of 5(5-norbornene-2,3-dicarboximido)isophthaloyl chloride (NCIC) and isophthaloyl chloride with bis(4-aminophenyl)methane, the ratio between both diacid chlorides being 0/100, 10/90, 15/85, 20/80, 25/75, 50/50, and 100/0. By 1H-NMR it has been proved that the composition of the copolymers closely coincided with the ratio of monomer's feeds.Properties such as solubility, glass transition temperatures, and thermal resistance have been measured and related to the copolymer's composition. Crosslinking studies have been carried out by DSC, and a comparison of properties of copolymers before and after thermal crosslinking has been made. The effect of crosslinking on the mechanical strength of copolymer films has also been measured.
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  • 9
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 203-212 
    ISSN: 0887-6266
    Keywords: poly(ester-imide)s ; liquid crystalline polymers ; dielectric relaxation ; model calculations ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two different series of poly(ester imide)s, which are distinguished from each other in the orientation of the ester linkages and show well-differentiated thermotropic behavior, are investigated by means of model calculations and dielectric relaxation spectroscopy. Model calculations show that the orientation of the ester linkages has a strong influence on the rotational energy barriers. The dielectric relaxation spectra of both series shows three relaxation regions in the temperature range between 100 and 400 K that have been identified as the α-, β- and γ-relaxation processes. A difference of about two orders of magnitude between the characteristic rates of the γ-relaxation is the main feature observed in the dielectric response. However, the β-relaxation shows very similar behavior for both series. The differences in the relaxation behavior in the solid state are interpreted on the basis of the rotational barriers deduced from the model calculation results. © 1997 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 35 (1997), S. 457-468 
    ISSN: 0887-6266
    Keywords: poly(ether amide)s ; mechanical relaxation ; dielectric relaxation ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The mechanical and dielectric relaxation of a set of aromatic-aliphatic polyamides containing ether linkages have been examined as a function of temperature (-140 to 190°C) and frequency (3 to 106 Hz). The polymers differ in the orientation (meta and para) of the aromatic rings, in the length of the aliphatic chain, and in the number of ether linkages per repeating unit. Dynamic mechanical experiments showed three main relaxation peaks related to the glass transition temperature of the polymers (α relaxation), the subglass relaxations associated to the absorbed water molecules (β) and to the motion of the aliphatic moieties (γ). Dielectric experiments showed two subglass relaxation processes (β and γ) that correlates with the mechanical β and γ relaxations, and a conduction process (σ) above 50°C that masks the relaxation associated to the glass transition. A molecular interpretation is attempted to explain the position and intensity of the relaxation, studying the influence of the proportion of para- or meta- oriented phenylene rings, the presence of ether linkages and the length of the aliphatic chain. © 1997 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys, 35: 457-468, 1997
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