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  • Polymer and Materials Science  (45)
  • Wiley-Blackwell  (45)
  • 2005-2009
  • 1995-1999  (23)
  • 1990-1994  (22)
  • 1
    Electronic Resource
    Electronic Resource
    Effect of crosslinking on the properties of poly(2-hydroxyethyl methacrylate) hydrogels (1991)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 189 (1991), S. 195-205 
    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: 2-Hydroxyethyl-methacrylat wurde durch Initiierung mit γ-Strahlung in Masse mit zwei verschiedenen tetrafunktionellen Monomeren (Ethylenglycol-dimethacrylat und 1,2-Bis(acryloxymethyl)-tetramethyldisiloxan) und einem hexafunktionellen Monomeren (1,1,1-Trimethylolpropan-trimethacrylat) als Vernetzungsmittel copolymerisiert. Die erhaltenen Xerogele wurden anschließend mit Wasser bis zum Erreichen der Gleichgewichtsquellung behandelt. Um die drei Vernetzungsmittel vergleichen zu können, wurde unter Berücksichtigung von Molmasse und Funktionalität der Xerogele die theoretische Konzentration an Vernetzungsstellen zwischen 0,032 und 0,644 mol/l variiert. Die relative Hydrophobie der drei Vernetzungsmittel hat einen ausschlaggebenden Einfluß sowohl auf die Gleichgewichtsquellung als auch auf den Elastizitätsmodul der gequollenen Gele. Der Gehalt an nicht-einfrierbarem Wasser in mit 1,1,1-Trimethylol-propan-trimethacrylat vernetzten Gelen wurde anhand von DSC-Untersuchungen analysiert. Das Verhältnis von nicht-einfrierbarem zum Gesamtgehalt an Wasser in den Gelen nimmt mit steigender Vernetzungsdichte zu.
    Notes: By means of γ-irradiation 2-hydroxyethyl methacrylate has been copolymerized in bulk with two different tetrafunctional monomers, ethylene glycol dimethacrylate and 1,3-bis(acryloxymethyl) tetramethyl disiloxane and with a hexafunctional monomer, 1,1,1-trimethylolpropane trimethacrylate. The resultant xerogels were subsequently swollen to equilibrium in water. In order to allow a comparison among the three crosslinkers, their molar masses and funtionalities were taken into account, the theoretical crosslink concentrations being varied from 0.032 to 0.644 mol dm-3. The relative hydrophobicity of the three crosslinkers was found to have a significant effect on both the equilibrium swelling and elastic modulus of the swollen gels. Non-freezing water in several gels crosslinked with 1,1,1-trimethylolpropane trimethacrylate was analysed by differential scanning calorimetry (DSC). The proportion of non-freezing water in the gel relative to the overall water content was found to increase with increasing crosslink density.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1991.051890118
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  • 2
    Electronic Resource
    Electronic Resource
    A facile synthesis of polyamides from aromatic diisocyanates and dicarboxylic acid catalyzed by Lewis acids (1996)
    Weinheim : Wiley-Blackwell
    Macromolecular Rapid Communications 17 (1996), S. 897-903 
    Details
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Aromatic polyamides were prepared by an AlCl3 or HCl-catalyzed polymerization of toluene diisocyanate or methylenebis(phenyl isocyanate) with adipic acid at low temperatures (≤100°C) in a short reaction time (3-4 h). The intrinsic viscosity of the polymers was approximately 1.1 dL/g as determined at 25°C with m-cresol as solvent, indicating that the polyamides obtained by this method have relatively high molecular weights. The polymers exhibit high glass transition temperatures and good thermal stability.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1996.030171208
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  • 3
    Electronic Resource
    Electronic Resource
    Studies on the application of matrix-assisted-laser-desorption-ionisation time-of-flight mass spectrometry to the determination of chain transfer coefficients in free radical polymerization (1998)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 199 (1998), S. 2403-2408 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The chain transfer coefficient (Cs) has been determined for 2-methyl-2-propanethiol (t-Bu-SH) in the solution polymerization of methyl methacrylate (MMA). Three different analytical methods were investigated. The Mayo and chain length distribution (CLD) methods yielded consistent Cs values of 0.12 and 0.13, respectively, at 60°C. A third, new approach to the evaluation of Cs values was also attempted using Matrix-Assisted-Laser-Desorption-Ionisation (MALDI) Time-Of-Flight Mass Spectrometry to analyse the end-groups of the polymer chains. The values of Cs obtained from MALDI analyses were not consistent with the other two methods and the relative intensities of the peaks with different end-groups were found to be dependent on the selection of cation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Critically evaluated rate coefficients for free-radical polymerization, 2.Part 1: cf. ref.1. Propagation rate coefficients for methyl methacrylate (1997)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 198 (1997), S. 1545-1560 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Pulsed-laser polymerization (PLP) in conjunction with molar mass distribution (MMD) measurement is the method of choice for determining the propagation rate coefficient kp in free-radical polymerizations. The authors, members of the IUPAC Working Party on Modeling of kinetics and processes of polymerization, collate results from using PLP-MMD to determine kp as a function of temperature T for bulk free-radical polymerization of methyl methacrylate at low conversions and ambient pressure. Despite coming from several different laboratories, the values of kp are in excellent agreement and obey consistency checks. These values are therefore recommended as constituting a benchmark data set, one that is best fitted by \documentclass{article}\pagestyle{empty}\begin{document}$ k_p = 10^{6,427} {\rm L} \cdot {\rm mol}^{ - 1} \cdot {\rm s}^{ - 1} \exp \left( {\frac{{ - 22,36{\rm kJ} \cdot {\rm mol}^{ - 1} }}{{R \cdot T}}} \right) $\end{document}The 95% joint confidence interval for these Arrhenius parameters is also given. In so doing, we describe the most appropriate statistical methods for fitting kp(T) data and then obtaining a joint confidence interval for the fitted Arrhenius parameters. As well, we outline factors which impose slight limitations on the accuracy of the PLP-MMD technique for determining kp, factors which may apply even when this technique is functioning well. At the same time we discuss how such systematic errors in kp can be minimized.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1997.021980518
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  • 5
    Electronic Resource
    Electronic Resource
    Contamination of surfaces: Origin, detection and effect on adhesion (1993)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 20 (1993), S. 368-372 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Surface contamination is one of the most insidious factors affecting adhesive bond performance and, hence, reliability of bonded structures. Sources of contamination are widespread and include primary materials, secondary materials, equipment, human operators, adjacent processes and the atmosphere. A successful approach to solving contamination problems involves the identification of the contamination and its source, establishment of the level of contamination that degrades the given bond, development of a plan to correct the problem and prevent contamination from occurring again, and subsequent verification of adequate substrate cleanlines prior to bonding. This generic approach is discussed and examples are cited to illustrate its use.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740200507
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  • 6
    Electronic Resource
    Electronic Resource
    Electrochemical behavior and surface chemistry of non-equilibrium aluminum-tantalum alloys: Solute-rich interphase mechanisms (1995)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 23 (1995), S. 609-617 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The electrochemical behavior and surface chemistry of sputter-deposited non-equilibrium stainless Al-Ta alloys have been investigated. These alloys exhibit enhanced passivity over a pH range of 2-12 even though the passive film chemistry varies considerably over this range. This enhanced passivity can be explained by the solute-rich interphase mechanism (SRIM), which states that formation and passivation of occluded cells are controlled by localized concentrations of solute. The higher concentrations of solute at the metaloxide interface and around occluded cells stabilize the passive-film from continued Cl- attack and dissolution.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740230906
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  • 7
    Electronic Resource
    Electronic Resource
    Surface Analysis by SNMS: Femtosecond Laser Postionization of Sputtered and Laser Desorbed Atoms (1996)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 24 (1996), S. 363-370 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The photoionization efficiency of secondary neutral atoms from metal surfaces has been investigated by very intense (∽1014 W cm-2) and short-pulsed (∽200 fs) 248 nm laser radiation. Surface erosion of the samples was performed by Ar+ ion sputtering and by laser desorption (LD) from an N2 gas laser. Five polycrystalline samples (Al, Cu, Zr, In and Au) have been analyzed with respect to their ionization efficiency and LD yields. In order to estimate the desorption yield, we determined the useful yield of our time-of-flight (ToF) mass spectrometer by ion sputtering, followed by laser postionization with 193 nm radiation from an ArF excimer laser. The applied femtosecond pulse, high-intensity 248 nm laser radiation has been found to be an excellent source of non-selective photoionization. For each material in this study a large fraction of doubly ionized atoms was observed; the measurements on Au have also shown triply ionized atoms. For some spectra, the number of doubly ionized atoms was even higher than for singly ionized atoms. We have estimated that the useful yields for LD are significantly higher than the values observed in ion sputtering.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Synthesis of porous hydrogel structures by polymerizing the continuous phase of a microemulsion (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 36 (1995), S. 219-226 
    Details
    ISSN: 0959-8103
    Keywords: microemulsion ; hydrogel ; poly(2-hydroxyethyl methacrylate) ; equilibrium water content ; oxygen permeability ; scanning electron microscopy ; 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: A series of microemulsions have been formulated, with 2-hydroxyethyl methacrylate (HEMA) or HEMA/water/propanol mixtures as the continuous phase and methylcyclohexane as the discontinuous phase. The effect of surfactant type was investigated with the utilization of both anionic and nonionic surfactants. The microemulsion continuous phase was polymerized by UV radiation and a thermal post-cure. The resultant polymers were extracted to remove the discontinuous phase and the surfactant. On swelling, the majority of the polymers became opaque, although transparent PHEMA hydrogels were synthesized with an improved equilibrium water content (EWC). The cause of opacity was shown by field emission scanning electron microscopy (FESEM). The breakdown in the microemulsion on polymerization is caused by unfavourable interactions between the PHEMA and the stabilizing surfactants causing agglomerization of the discontinuous phase. All the hydrogels were found to have higher water retention than PHEMA, with EWCs of up to 70%. The modified polymers also demonstrated an increased rate of water diffusion into the matrix. A preliminary study of oxygen permability revealed that a significant improvement had been made over standard PHEMA membranes. The porous structure of the PHEMA gels has been shown to be dependent on the type of surfactant used during synthesis.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pi.1995.210360301
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  • 9
    Electronic Resource
    Electronic Resource
    A molecular orbital study of the interactions of acrylic polymers with aluminum: Implications for adhesion (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 28 (1990), S. 3185-3219 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We present results of molecular orbital thory calculations of the interactions of acrylic polymers with aluminum, with a view toward understanding the nature of chemical bonding at the corresponding polymer-metal interfaces. The reported results are for the interactions of polymer model compounds with metal atoms (as opposed to our ongoing studies with metal surfaces). As such, the results relate to experimental studies where small dosages of metal atoms are evaporated onto polymer surfaces in pristine high vacuum environments. Our studies have been conducted within the theoretical framework of Hartree-Fock molecular orbital theory. We find that aluminum atoms interact primarily with the carbonyl group of acrylic polymers. The reaction proceeds by the metal atoms interacting with both the carbon and the oxygen atoms of the carbonyl functionality. This weakens the C=O bond. Finally, the carbonyl bond loses double bond character, and strong AL - O bonds are formed. Our results are compared to experimental data, and the implications of the detailed nature of bonding for adhesion applications are discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1990.080281201
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  • 10
    Electronic Resource
    Electronic Resource
    Determining the chromophore in the amylopectin-iodine complex by theoretical and experimental studies (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 32 (1994), S. 2257-2265 
    Details
    ISSN: 0887-624X
    Keywords: helix in amylopectin-iodine complex ; I4 unit in amylopectin-iodine complex ; spectra of amylopectin-iodine complex ; amylopectin-iodine chromophore composition ; amylopectin fine structures and complex formation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A partial hydrolysis of amylose followed by the addition of iodine provides a spectrum almost identical to that of the amylopectin-iodine (API) complex suggesting the involvement of smaller “amylose-like” units in the API complex. Our theoretical studies on different polyiodine and polyiodide species suggest that a nearly linear I4 unit stabilized within the cavity of a small “amylose-like” helix is responsible for the characteristic API spectrum. Since there are 2.75 anhydroglucose residues (AGU) for every iodine atom in the amylose-iodine (AI) complex and a structural similarity exists between the API and the AI (amylose-iodine) complexes, we identify (C6H10O5)11I4 to be the chromophore in the API complex. © 1994 John Wiley & Sons, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1994.080321207
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