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  • 1
    Electronic Resource
    Electronic Resource
    Kinetics of thermal degradation of semi-stiff macromolecules II. Poly-N-vinyl-carbazolPresented at the International Symposium on Degradation and Stabilization of Polymers held in Brussels (Belgium), 11-13 September, 1974. (1975)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 43 (1975), S. 105-123 
    Details
    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 thermische Abbau von Poly-N-vinyl-carbazol (PVK) wurde mittels „flash“-Pyrolyse, kontrollierter Pyrolyse und dynamisch-thermogravimetrischer Analyse untersucht. Die Analyse der Abbauprodukte erfolgte über Gas-Flüssig-Chromatographie sowie Massenspektrometrie als Trennungs- und Identifizierungsverfahren. Das untersuchte PVK wurde durch radikalische Polymerisation in Benzol mit AIBN als Katalysator dargestellt.Aus den Versuchsergebnissen ergibt sich, daß PVK fast vollkommen über einen stufenweisen „unzipping“ Mechanismus in das Monomere zerfällt. Die Zusammensetzung der Pyrolysate ermöglicht eine Formulierung des Abbaumechanismus des Polymeren. Mit Hilfe des Verfahrens der multiplen Aufheizgeschwindigkeiten wurde die Kinetik des thermischen Abbaus untersucht. Die Bruttoaktivierungsenergie der Depolymerisation wurde zu 40 kcal/mol gemessen und für die Reaktionsordnung wurde ungefähŕ 1 gefunden.Es werden einige thermodynamische Betrachtungen aufgeführt, um den Wert der Aktivierungsenergie des gesamten Prozesses zu erklären. Es wird ein Mechanismus vorgeschlagen.
    Notes: The thermal degradation of poly-N-vinyl-carbazol (PVK) has been studied using flash pyrolysis, controlled pyrolysis and programmed thermogravimetry analysis techniques. The degradation products have been analyzed using gas-liquid chromatography and mass spectrometry as separation and characterization techniques. The examined PVK has been prepared by free radical polymerization in benzene using AIBN as catalyst.It is shown from experimental results that PVK breaks up almost completely into the monomer through a stepwise unzipping mechanism. The composition of the pyrolyzate allows to propose a mechanism for the polymer degradation. Thermal degradation rates have been analyzed using a multiple heating rates procedure. A value of 40 kcal/mol has been found for the overall activation energy of depolymerization and a value approximately equal to one for the order of reaction.Some thermodynamic considerations have been made in order to explain the value of the activation energy of the whole process. A mechanism is suggested.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1975.050430108
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  • 2
    Electronic Resource
    Electronic Resource
    Electrochemical behavior of aromatic amines protected by the nitrobenzenesulfonyl group (1995)
    Weinheim : Wiley-Blackwell
    Electroanalysis 7 (1995), S. 365-369 
    Details
    ISSN: 1040-0397
    Keywords: Aromatic amines ; Reduction ; Mechanism ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electrochemical reduction of aniline protected by the 4-, 3-, or 2-nitrobenzenesulfonyl group in N,N-dimethylformamide (DMF) at a vitreous carbon electrode is reported. The compounds are reduced in three cathodic steps. The first reduction step at about -0.85 V vs. SCE occurs with the formation of an unstable anion radical, which decomposes via N—H bond cleavage. Reduction of this sulfonamide anion occurs at -1.16 V for para and meta isomers and at -1.48 V for the ortho isomer. The third cathodic step occurs at higher cathodic potentials. The B—H bond cleavage is always the preponderant process. The mechanisms of the reduction are discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140070412
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  • 3
    Electronic Resource
    Electronic Resource
    Spectroscopic studies of surface copper spinels. Influence of pretreatments on chemical state of copper (1993)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 20 (1993), S. 1067-1074 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The nature of copper species of a series of alumina-supported copper samples was investigated by the kinetics of reduction, x-ray photoelectron spectroscopy, temperature-programmed desorption-mass spectrometry of chemisorbed NO and infrared spectroscopy of chemisorbed NO and CO probes. The role of these copper species was also examined in the catalytic decomposition of NO. The surface properties of copper were found to depend strongly on both Cu loading and calcination treatment. At Cu contents as low as 0.6 wt.%, Cu2+ ions from a well-dispersed interacting phase at the alumina surface, which upon calcination forms a surface spinel CuAl2O4. At copper contents up to 3.2 wt.%, both the surface spinel CuAl2O4 and a segregated CuO phase were clearly distinguished. The partial reduction of these species upon thermal treatment under high vacuum, the ability of the surface sites to chemisorb NO and CO probes and their implications in the catalytic decomposition of NO are discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740201307
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  • 4
    Electronic Resource
    Electronic Resource
    Polymerization of N-(fluoro phenyl) maleimidesPaper presented in part before the IUPAC, International Symposium on Macromolecules (SIM) held in Rio de Janeiro, Brazil, 26-31 July 1974. (1979)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 17 (1979), S. 81-96 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Poly(N-aryl maleimide)s of characteristic structures have been synthesized and some of their physical properties studied. These include N-(2-fluoro phenyl), N-(3-fluoro phenyl), N-(4-fluoro phenyl), N-(2,4-difluoro phenyl), N-(2,5-difluoro phenyl), N-(2,3,5,6-tetrafluoro phenyl), and N-(pentafluoro phenyl). The polymerization of N-(fluoro phenyl) maleimides by free-radical initiation in bulk or in solution and by anionic catalyst have been studied to compare the characteristics of polymerization by γ-ray irradiation with that by free-radical initiation. The polymers were characterized by elemental analysis, intrinsic viscosity, spectroscopy (IR and NMR), programmed thermogravimetric analysis, and x-ray diffraction. Spectra of polymers prepared by radiation and anionic polymerization were nearly identical with those of polymers prepared by free-radical polymerization initiated by AIBN in bulk or in solution and by the self-initiated thermal polymerization. A variety of reaction conditions were tried, but all attempts to change the molecular structure of the polymers were unsuccessful. Rates of thermal degradation for poly[N-(fluoro phenyl) maleimide]s have been analyzed by using a multiple-heating-rate procedure. Overall activation energy, order of reaction, and frequency factor have been evaluated. On the basis of the comparison between the overall activation energy of the thermal degradation of poly[N-(fluoro phenyl) maleimide]s and NMR spectra of their corresponding monomers, it can be concluded that the 1H shifts due to ethylenic protons are so characteristic in sign and magnitude as to be useful in thermal stability elucidation. Some qualitative explanations were given on the stability of these polymers as affected by the type and size of the substituent. The x-ray diffractograms of all samples show two rather broad peaks indicative of noncrystalline structures. The location of the peaks does not depend upon preparation conditions and temperature. Poly(N-maleimide)s of fluoroanilines have not been hitherto described.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1979.170170109
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of epoxidized phenolic novolacs modified by furfuryl alcohol (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 37 (1995), S. 21-26 
    Details
    ISSN: 0959-8103
    Keywords: epoxidation ; novolacs ; furan resins ; furfuryl alcohol ; epoxidized novolacs ; furfuryl alcohol-phenol reaction ; 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
    Notes: The possibility of reacting furfuryl alcohol with the p-position of phenolic rings, under acid conditions, was proved using different experimental techniques: size exclusion chromatography, Fourier transform infrared spectroscopy and 13C NMR. This reaction was then used in the modification of phenolic novolacs with furfuryl alcohol. After reaction with epichlorohydrin, epoxidized phenolic novolacs (EPN) modified with furan rings were obtained. They could be cured with aromatic diamines in a similar way to conventional EPNs. The presence of furan rings should improve burning resistance and smoke emission characteristics of the resulting networks.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pi.1995.210370102
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  • 6
    Electronic Resource
    Electronic Resource
    Molecular motions in poly(vinyl acetate) revisited. A thermally stimulated current study (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 33 (1994), S. 293-302 
    Details
    ISSN: 0959-8103
    Keywords: dielectric relaxation ; dipolar relaxation ; thermally stimulated current ; thermally stimulated depolarisation current ; poly(vinyl acetate) ; amorphous polymer ; glass transition ; compensation effect ; liquid-liquid transition ; 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
    Notes: The dipolar relaxation mechanisms in poly(vinyl acetate) have been studied in detail using the technique of thermally stimulated currents. The papers published in the literature about this subject are very contradictory, particularly with respect to the assignment of the observed discharges to the corresponding motions at the molecular level. This work aims at clarifying these problems. We detected and characterised three different relaxation mechanisms: (1) a low temperature one (around -140°C) which was attributed to local internal rotations in the acetate side-groups; (2) a relaxation whose maximum occurs at 42°C, which corresponds to the glass transition relaxation, and shows a compensation behaviour; (3) an upper glass transition relaxation whose maximum appears at 87°C and was attributed to a liquid-liquid transition. These assignments have been made on the basis of the analysis of the behaviour of the samples when submitted to different thermal and electrical treatments.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pi.1994.210330309
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  • 7
    Electronic Resource
    Electronic Resource
    Compatibility studies on blends of poly(ethylene ortho-phthalate) and poly(vinyl acetate) (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 32 (1986), S. 6095-6106 
    Details
    ISSN: 0021-8995
    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
    Notes: Blends of poly(ethylene ortho-phthalate) (PEOP), and poly(vinyl acetate) (PVAc), appear to be compatible at all compositions, from visual examination at room temperature and differential scanning calorimetry tests. Both low- (PEOP-1) and high-molecular weight (PEOP-2) alloys with PVAc show a single composition-dependent glass transition temperature (Tg). Some blends show Tg values that are below the Tg for either of the pure polymers. Couchman's equation, with a slight modification, can be used to model Tg behavior. All PEOP-2 blends with PVAc, phase separate at high temperatures, whereas PEOP-1-PVAc blends remain miscible under the same conditions. The composition dependence of the blends refractive index shows a deviation from simple additivity rules, and a similar trend is observed in density measurements. When comparing Flory's characteristic parameters for the polymers, compatibility is predicted for PVAc-PEOP blends. In contrast, blends of PEOP and poly(methyl methacrylate) (PMMA), which has a similar chemical structure to that of PVAc are predicted to be incompatible, in agreement with experimental evidence. It is suggested that compatibility is produced because of possible specific interactions between the aromatic group of PEOP and the ester carbonyl on PVAc, which is not sterically hindered as is the corresponding moiety on PMMA.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1986.070320735
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  • 8
    Electronic Resource
    Electronic Resource
    Coconut husk lignin. I. Extraction and characterization (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 633-644 
    Details
    ISSN: 0021-8995
    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
    Notes: Recently lignin has been the object of a renewed interest because of the need to use raw materials from renewable resources. One such resource is coconut husk, a material usually discarded during the copra extraction process. Due to its high lignin content, coconut husk has been recognized as having a variety of applications. Therefore, it is important to know the approximate structure of coconut husk lignin and those variations introduced by different isolation methods. This work reports a general characterization of coconut husk lignin. Results are given of the contents of hydroxyl and noncondensed guaiacyl units, the extractability of the lignin in alkaline and “organosolv” media along with thermal properties of the extracted lignins. The extraction system of NaOH-anthraquinone at 150°C was most conveniently based on the relatively low amount of condensed lignin generated.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070450410
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  • 9
    Electronic Resource
    Electronic Resource
    Coconut husk lignin. II. Characterization by infrared and nuclear magnetic resonance spectroscopy (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 645-653 
    Details
    ISSN: 0021-8995
    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
    Notes: Results of the characterization of coconut husk lignin by infrared (IR) and proton nuclear magnetic resonance (H-NMR) spectroscopy are presented. Lignin was extracted with both alkaline and organosolv liquors. The IR spectra of dioxane lignin were very similar to those reported for hardwood lignins. Furthermore, these results combined with those obtained from the H-NMR studies suggest that coconut husk lignin can be classified into the Lm-type lignins. These lignins are characteristic of the monocotyledon class, of which the coconut palm is a member. The H-NMR studies showed that anthraquinone significantly inhibited the occurrence of lignin condensation during the alkaline extraction with sodium hydroxide solutions. This inhibition was more intense in the lignin extracted at 150°C than in that extracted at 100°C.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070450411
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  • 10
    Electronic Resource
    Electronic Resource
    Coconut husk lignin. III. Reactivity of alkaline extracts with formaldehyde (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 47 (1993), S. 37-44 
    Details
    ISSN: 0021-8995
    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
    Notes: In this article we report results of the evaluation of the reactivity of polyphenolic extracts of coconut husk with formaldehyde in both acidic and alkaline media. The objective of this evaluation was to determine if the extracts could be used in the preparation of phenol-formaldehyde-type resins. Extracts were obtained using aqueous solutions of NaOH (with and without anthraquinone) and NH4OH. Because of their low Stiasny's Number values, these extracts are not suitable for phenol-formaldehyde resin preparation in acidic conditions unless they are mixed with phenol or phenolic derivatives. Nevertheless, extracts obtained with NaOH, especially at 100 and 120°C, showed sufficient reactivity with form-aldehyde in basic conditions and may therefore be considered suitable for resin preparation in an alkaline medium. The resins were characterized using infrared spectroscopy (IR), differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). A transition temperature prior to decomposition was not detected; their thermal stability was similar to phenol-formaldehyde-type resins. © 1993 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070470106
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