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  • GEOPHYSICS  (55)
  • Polymer and Materials Science  (34)
  • 1995-1999  (18)
  • 1990-1994  (71)
  • 1
    Electronic Resource
    Electronic Resource
    Grafting of 2-(dimethylamino)ethyl methacrylate on linear low density polyethylene in the melt (1990)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 181 (1990), S. 1-22 
    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: Das Pfropfen von 2-(Dimethylamino)ethyl methacrylat (DMAEMA) auf lineares Polyethylen niedriger Dichte (LLDPE) in der Schmelze wurde mittels Messungen des Monomerumsatzes, des Pfropfgrades und der Pfropfeffizienz untersucht. Die Ergebnisse zeigen, daß das Pfropfen von DMAEMA auf LLDPE bereits bei niedrigen Temperaturen von etwa 90°C in der Schmelze durchgeführt werden kann, obwohl der Schmelzpunkt von LLDPE bei etwa 120°C liegt. Wenn die Pfropfreaktion bei zu hohen oder zu niedrigen Temperaturen durchgeführt wird, kann nur ein sehr niedriger Pfropfgrad beobachtet werden. Hohe Reaktionstemperaturen begünstigen die Polymervernetzung, was sich im Absinken des Schmelzindex bemerkbar macht. Die meisten Pfropfvorgänge werden während der Anfangsphase der Reaktion (unter den vorliegenden Bedingungen während der ersten 3 min) beobachtet. Eine Verlängerung der Reaktionsdauer über diesen Zeitraum hinaus führt zu verstärkter Vernetzung und erhöhter Produktion des Homopolymeren, was die Effizienz des Prozesses verringert. Organische Peroxide sind über einen weiten Halbwertszeitenbereich effektive Initiatoren der Pfropfreaktion, während Azoinitiatoren keine Pfropfung bewirken.
    Notes: Grafting of 2-(dimethylamino)ethyl methacrylate (DMAEMA) on linear low density polyethylene (LLDPE) in the melt has been studied through measurements of monomer conversion, the degree of grafting and the grafting efficiency. Results show that the grafting of DMAEMA on LLDPE can be carried out in the melt at temperatures as low as 90°C even though the melting point of the LLDPE is as high as 120°C. When the grafting reaction is carried out at too low or too high temperature, a low degree of grafting is observed. High reaction temperature favoured crosslinking of the polymer as indicated by decreasing melt flow index. Most of the grafts were obtained during the early period of the reaction (before 3 min under the reaction conditions used). Further increase in reaction time increased crosslinking and also produced more homopolymer, thus decreasing the grafting efficiency. Organic peroxides are effective initiators for the grafting reaction over a broad range of half-lives while azo initiators do not produce grafting.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1990.051810101
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  • 2
    Electronic Resource
    Electronic Resource
    Hysteresis in the glucose permeability versus pH characteristic for a responsive hydrogel membrane (1996)
    Weinheim : Wiley-Blackwell
    Macromolecular Rapid Communications 17 (1996), S. 409-415 
    Details
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A side-by-side diffusion cell was used to study the permeability of glucose through a temperature- and pH-sensitive poly(N-isopropylacrylamide-co-methacrylic acid) hydrogel membrane. At fixed temperature (37°C), lowering pH in one side of the cell induced hydrogel volume collapse and strongly attenuated glucose permeation across the membrane. Hysteresis was observed in the glucose permeability versus pH characteristic.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1996.030170607
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  • 3
    Electronic Resource
    Electronic Resource
    A Study of the Chemical Bonding and Microstructure of Ion Beam-deposited CNx Films Including an XPS C 1s Peak Simulation (1997)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 25 (1997), S. 629-642 
    Details
    ISSN: 0142-2421
    Keywords: XPS ; FTIR ; carbon nitride ; thin film ; simulation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The chemical bonding and microstructure of dual ion beam-deposited CNx films with nitrogen contents in the range 20-33 at.% have been examined by Fourier transform infrared spectroscopy (FTIR) and x-ray photoelectron spectroscopy (XPS). The FTIR spectra together with other published data have been used to construct a model microstructure of the CNx films. The XPS N 1s peak is composed of two components corresponding to N-sp2 C and N-sp3 C bonds. Using the quantified N 1s data and making certain assumptions, the model microstructure has been used as the basis of a C 1s peak simulation in which nine C components have been combined. At an N content of 20 at.% the simulation agrees well with the experimentally recorded XPS C 1s peak. The FTIR spectra, XPS N 1s peak shape and C 1s peak simulations support a microstructure of N substitution into an amorphous sp2/sp3 hybridized carbon structure. Above an N content of ∽20%, a new (nitrile-like) chemical form also emerges in the material, its abundance increasing with N content. It is proposed that this new structure occurs due to the presence, in the surface region of the condensing film, of C≡N dimers, which are formed when a C atom is surrounded by many N atoms. This molecule becomes trapped in the material and bonds to atoms at neighbouring sites. © 1997 by John Wiley & Sons, Ltd.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Auger electron spectroscopy studies on TiNx (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 22 (1994), S. 167-170 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A new method for the determination of N/Ti ratio for TiNx samples has been proposed. High energy resolution Auger spectra recorded of the Ti L3M23M45 peak have shown that on nitridation of Ti to TiNx a second peak, labelled the L3M23Hybrid peak, emerges at 3.9 eV below the L3M23M45 peak in the raw data, which grows with the grade of nitridation. After a simple Shirley background correction a linear dependence between the ratio of the L3M23Hybrid/L3M23M45 peak height of the raw data and the N/Ti ratio was found. This relation can be used directly to evaluate the nitrogen content of an unknown TiNx compound by recording only the Ti L3M23M45 region. The changes of the L3M23M45 peak structure have been interpreted and compared with earlier DOS calculations for Ti and TiN. Good agreement between experiment and theory was found, enabling a discussion of the valence electronic structure changes for Ti on nitridation.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740220137
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  • 5
    Electronic Resource
    Electronic Resource
    The application of chemical state AES and SAM to the examination of spray-formed aluminium alloy fracture surfaces (1993)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 20 (1993), S. 589-594 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The fracture surface of a spray-formed Al-5.2Cr-1.4Zr alloy has been examined using AES and scanning Auger microscopy (SAM). Cratered regions of the surface were identified and high-energy resolution AES analysis showed a localized 20 Å thick Al2O3 film to be present in these areas. Chemical-state imaging of the Al fracture surface enabled the local distribution of oxide to be determined. The surface topography was not found to be suppressed using the standard (P—B)/B or (P—B)/(P + B) correction algorithms. This point is discussed with consideration of the electron emission from such highly structured surfaces. The oxide thickness measured from the craters is in good agreement with that previously determined by XPS for powder particles produced in the atomization process. Crater formation is suggested to occur as a result of complete powder particle solidification prior to the particles impacting the substrate/deposit. The localized oxide, revealed by fracture, presents areas of weakness in the unworked material.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740200708
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  • 6
    Electronic Resource
    Electronic Resource
    An interfacial study of a sigma fibre/Ti-6Al-4V composite using scanning Auger/EDX microscopy (1994)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 22 (1994), S. 308-313 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The interfacial region of a Sigma fibre/Ti-6Al-4V composite has been studied by Auger/EDX microscopy. The SiC fibre has a duplex coating consisting of an inner layer of C and outer TiBx layer. Point analyses, line scans and images were acquired from the fibre/matrix interface region for a specimen taper sectioned at 10° to the fibre axis and a sample fractured in situ along the fibre length. Fracture of the composite reveals the presence of a brittle B rich oxide layer probably of the form TixByO at the boride coating/matrix interface. The fracture path occurs either through this oxide or the graphitic carbon layer. C is shown to have diffused through the entire boride coating. B diffuses from the TiBx layer into the matrix, forming TiB at the interface. The presence of excess boron in the coating and the strong affinity of B for O are proposed as the main driving forces for oxide formation at the TiBx/matrix interface.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740220167
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  • 7
    Electronic Resource
    Electronic Resource
    The application of surface imaging techniques to the study of pitting corrosion initiation in stainless steels (1993)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 20 (1993), S. 535-543 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: A combined Auger, EDX and SEM surface imaging study of the initial stages of pitting corrosion is presented. Examples of different pitting initiation situations are shown and the importance of multi-technique imaging to interpret the results is demonstrated. The information provided by the images is compared with theories established primarily from electrochemical results. The development of scanning probe microscopies presents the opportunity of directly studying pitting initiation using imaging. Initial atomic force microscopy images of the corrosion of sulphide inclusions in stainless steels are given and the possible capabilities of the technique for application in this field are considered.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740200609
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  • 8
    Electronic Resource
    Electronic Resource
    Functionalization of polyethylenes and their use in reactive blending (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 2285-2300 
    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: The grafting of maleic anhydride (MAn) to low density polyethylenes (PEs) dissolved in 1,2-dichlorobenzene (DCB) has been studied. Grafting was successful at temperatures of about 160°C both in air without initiator and under nitrogen with the radical initiator 2,5-di(t-butylperoxy)-2,5-dimethyl-3-hexyne (LPO). The presence of succinic anhydride grafts was shown by FTIR spectroscopy of the product; 1H-NMR spectroscopy indicates that the grafts consist of single succinic anhydride units. The graft content was determined by nonaqueous titration, and the extent of crosslinking inferred from the melt flow rates (MFR) of the products. The effects of concentration of initiator, MAn, and PE on the graft content were determined; the influence of PE structure, reaction time, and temperature was also studied. Melt blending of the grafted PE with polystyrene containing oxazoline functional groups (OPS) was investigated using a Rheomix mixer. The interpolymer reaction which occurs during blending was studied by means of FTIR, and the morphology of the blends by scanning electron microscopy (SEM). Information was also gained from the change in torque viscosity during the blending process.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070410931
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  • 9
    Electronic Resource
    Electronic Resource
    In situ compatibilization of polystyrene/polyethylene blends using amino-methacrylate-grafted polyethylene (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 2167-2177 
    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 a styrene-maleic anhydride copolymer (SMA) with polyethlene (PE) or polyethylene melt grafted with tertiary (PE-g-DMAEMA) or secondary (PE-g-tBAEMA) amino methacrylate were prepared by blending in a batch melt mixer. The morphology of these blends at various compositions was examined with a scanning electron microscope (SEM) and related to their tensile and impact properties. The SMA/PE blends are found to have the typical coarse morphology of incompatible blends and poor mechanical properties, while their reactive conterparts, SMA/PE-g-DMAEMA or SMA/PE-g-tBAEMA blends, show finer morphology and modestly improved tensile and impact strength. This was attributed to chemical interaction of the acidic anhydride and the basic amino groups. The greater improvement in morphology for SMA/PE-g-tBAEMA than for SMA/PE-g-DMAEMA suggests a stronger interaction between the secondary amino groups and the anhydride groups, possibly with the formation of SMA-g-tBAEMA-g-PE graft polymer through amide covalent bonds. The amide formation appears to occur at the interfacial region in the blends and is too little to be detected by Fourier transform infrared (FTIR) spectra. However, differential scanning calorimeters (DSC) and the viscosity measurements indicate crystallinity and molecular weight changes for the SMA/PE-g-tBAEMA blends, supporting an argument for the formation of SMA-g-tBAEMA-g-PE grafts at the phase interface.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070441213
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  • 10
    Electronic Resource
    Electronic Resource
    Search for nonoxidative, hydrogen-abstracting initiators useful for melt grafting processes (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 48 (1993), S. 1199-1208 
    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: Using organic peroxide initiators in the melt grafting of monomers containing amino groups onto polyethylenes is known to cause serious discoloration of the resulting polymers. To eliminate the discoloration while preserving the controlled degree of grafting, a nonoxidative and hydrogen-abstracting initiator with appropriate thermal stability is needed. In this study, the hydrogen-abstracting capability of three azo initiators with suitable decomposition rates in the melt grafting temperature ranges was evaluated using polyethylene cross-linking and polypropylene degradation experiments (called “hydrogen-abstracting experiments”). Among the three azo initiators tested, only a phenylazo initiator, 2 - phenylazo - 2,4 - dimethyl - 4 - methoxyl - valeronitrile (V-19), demonstrated strong hydrogen-abstracting capability from polymer backbones. These three azo initiators were used in the melt grafting of 2 - (N, N - dimethylamino) ethyl methacrylate (DMAEMA) and 2-(N-t -butylamino) ethyl methacrylate (tBAEMA) onto a linear low-density polyethylene (LLDPE). In agreement with the results obtained from the hydrogen-abstraction experiments, only V-19 led to a considerable amount of grafting of both DMAEMA and tBAEMA onto LLDPE. As expected, polymers grafted with V-19 showed significantly reduced discoloration compared with those grafted with peroxide initiators. Further examination of the grafting results indicated that the initiator efficieny, defined as the number of grafted monomer units per radical generated from initiator decomposition, was higher with the phenylazo initiator than with peroxide initiators. The hydrogen-abstracting capability of the phenyl free radical generated from the decomposition of V-19 was estimated to be higher than peroxide and methyl free radicals produced in the decomposition of peroxide initiatros. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070480708
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