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  • 1
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 31 (1996), S. 5153-5157 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The microhardness of films of fullerene-polyethylene composites prepared by gelation from semidilute solution, using ultrahigh molecular weight polyethylene (PE) (6×106), has been determined. The composite materials were characterized by optical microscopy and X-ray diffraction techniques. The microhardness of the films is shown to increase notably with the concentration of fullerene particles within the films. In addition, a substantial hardening of the composites is obtained after annealing the materials at high temperatures (T a=130 °C) and long annealing times (t a=105s). The hardening of the composites with annealing temperature has been identified with the thickening of the PE crystalline lamellae. Comparison of X-ray scattering data and the microhardness values upon annealing leads to the conclusion of phase separation of C60 molecules from the polyethylene crystals within the material. The temperature dependence is discussed in terms of the independent contribution of the PE matrix of the C60 aggregates to the hardness value.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1435-1536
    Keywords: Key words Polyethylene ; Pendant group ; γ-ray irradiation ; 1 ; 3-Butadiene ; Double bond
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Ultra-high-molecular-weight polyethylene (M¯ v: 5 × 106, 100-times elongated film) was irradiated with γ-rays under a 1,3-butadiene atmosphere at room temperature. Electron paramagnetic resonance (EPR) measurements indicated that the radicals formed on the polyethylene substrate during the irradiation were short-lived. EPR, Fourier transform IR spectroscopy, solid-state NMR, and differential scanning calorimetry of the as-irradiated materials indicated that butadiene molecules were covalently bound to the polyethylene chains as pendant groups bearing trans-vinylene and vinyl functions in a ratio of 3:1. Some crosslinks among the pendants, or between pendants and the main chains were produced. The number of unsaturated pendants introduced (including bridges) per carbon atom of the polyethylene main chain was dependent on the irradiation dose and the butadiene pressure, and was 0.096 butadiene units for 10 kGy irradiation under a 304 kPa butadiene atmosphere. The unsaturated pendants or bridges on the polyethylene chain thus introduced may be good targets to functionalize polyethylene by covalent modification.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1435-1536
    Keywords: Polyethylene-polyethylene blend films ; electron beam ; radiation doses ; cross-linking ; high temperature resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Polyethylene-polyethylene blend films were prepared by gelation/crystallization from semidilute solution by using ultrahigh molecular-weight (mw) polyethylene (UHMWPE) (mw=6×106) and low molecular weight polyethylene (LMWPE) (mw=4×104). The UHMWPE/LMWPE compositions chosen were 50/50, 67/33, and 91/9. Elongation was carried out in a hot oven at 115–130°C. The drawn films were exposed to an electron beam under nitrogen flow. Radiation doses chosen were 10, 20, 40, and 100 Mrad. crosslinking caused a significant effect in improving high temperature resistance for the blend film with draw ratio of 20 in the case of irradiation doses less than 20 Mrad. The elongation beyond 20 times and high doses beyond 20 Mrad hampered the crosslinking effect and the specimens were easily torn manually. This is thought to be due to the fact that the excess irradiation dose causes main chain scission apart from crosslinking.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1435-1536
    Keywords: Polyethylene ; ultra-highmolecular weight ; electron-beam irradiation ; crosslinks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Cross-linking of ultra-high molecular weight polyethylene was performed with electron-beam irradiation in the range of radiation dose from 12 to 96 Mrad under nitrogen. Dry gel films and melt films were used as specimens. Two kinds of cross-linked specimens could be kept at 200°C for a prolonged time in an undeformed state and this tendency was independent of radiation dose. The elongation of the gel films hampered the heat-resistant effect and the drawn specimens were broken at temperatures lower than 175 °C. The elongation of the melt films could not be realized, because of a marked fixation of chains in the fiber network, even at a dose of 12 Mrad.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 263 (1985), S. 783-790 
    ISSN: 1435-1536
    Keywords: Ultradrawn polyethylene ; storage modulus E' ; radiation dose ; radiation-induced scission
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper is concerned with the temperature dependence of mechanical properties of ultradrawn polyethylene in terms of storage modulus E' and loss factor tanδ by the measurement of the complex dynamic tensile modulus over ranges of temperature from 20 to 140
    Type of Medium: Electronic Resource
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