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  • 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
    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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  • 3
    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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  • 4
    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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  • 5
    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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  • 6
    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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  • 7
    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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  • 8
    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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  • 9
    Electronic Resource
    Electronic Resource
    Basic functionalization of molten linear low-density polyethylene with 2-(dimethylamino)ethyl methacrylate in an intermeshing corotating twin-screw extruder (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 1299-1313 
    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: Functionalization of molten linear low-density polyethylene (LLDPE) with 2-(dimethylamino)ethyl methacrylate (DMAEMA) was studied in an intermeshing co-rotating twin-screw extruder using a peroxide initiator. The influence of monomer concentration, initiator concentration, reaction temperature, the screw speed, and the mean reaction residence time on the grafting reaction was investigated in order to determine the reaction conditions necessary to obtain a controlled degree of grafting, DG, while minimizing homopolymerization and crosslinking. Relatively high grafting levels can be obtained without excessive polyethylene crosslinking by using high monomer concentrations, wm, with low initiator concentrations, wI. DG increased with increasing monomer concentration when wm exceeded a certain value. Processing temperatures between 130 and 160°C are optimal to achieve high grafting efficiency, GE. Too high a processing temperature resulted in both low DG and GE. An optimal reaction residence time of about 5 min was found for wm = 23 wt % and wI = 0.56 wt % to obtain relatively high DG and GE. The melt flow index of the reaction product, MFI, increased with increasing wm at constant wI. This suggests that the DMAEMA monomer has the ability to suppress crosslinking of the LLDPE chains. The ability of the DMAEMA monomer to compete for initiator and polymer radicals and reduce LLDPE crosslinking was further demonstrated by the study of sequential addition of monomer and initiator along the extruder. The competition among the three reactions (i.e., the desired grafting, homopolymerization, and crosslinking) is discussed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070410537
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  • 10
    Electronic Resource
    Electronic Resource
    In situ reactive compatibilization in polymer blends: Effects of functional group concentrations (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 39 (1990), S. 655-678 
    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: Polystyrene (PS) and polyethylene (PE), along with their reactive counterparts, i.e., polystyrene having oxazoline reactive groups (OPS) and polyethylene with carboxylic acid groups (CPE), were melt blended in a Rheomix mixer. These blends were prepared by mixing these polymers in various proportions under a variety of conditions. In an alternate procedure the OPS, CPE graft polymer (OPS-g-CPE) was prepared by melt blending these two polymers beforehand, and subsequently this grafted polymer was used as a compatibilizer for PS-PE blends. The effects of the addition of OPS and CPE, on the one hand, and OPS-g-CPE, on the other hand, on the compatibility of PS-PE blends were investigated. The morphology of these blends was examined with a scanning electron microscope (SEM) and related to their tensile properties. The PS-PE blends are found to have the typical coarse morphology of incompatible blends and poor tensile properties while their reactive counterparts, OPS-CPE blends, have fine grain microstructure and show improved tensile strength throughout the range and improved elongation in the PE-rich blends. Relatively low concentrations of the reactive pair, oxazoline and carboxylic acid, are shown to be necessary to produce improved compatibility. The preblended graft copolymer OPS-g-CPE imparts compatibility to PS-PE blends also but not as effectively. This suggests that the addition of OPS and CPE during melt mixing of PS and PE forms OPS-g-CPE polymer at the interface and that these ingredients act as “in situ reactive compatibilizers” which improve physical properties.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070390316
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