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  • 1
    Electronic Resource
    Electronic Resource
    Mechanism of decay of alkyl radicals in irradiated polyethylene on exposure to air as studied by electron spin resonance (1973)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 77 (1973), S. 40-44 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100620a008
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of Firing Temperature on the Thermal Stability of Low-Oxygen Silicon Carbide Fibers (1998)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 81 (1998), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Low-oxygen SiC fibers which were fabricated by curing with electron-beam irradiation and firing at 1273 and 1573 K (fiber-A and fiber-B) were exposed at 1673 to 1973 K. Significant differences in surface composition, crystallinity, specific resistivity, and tensile strength were found between fiber-A and fiber-B. On exposing the fibers to high temperatures, they both crystallized nearly completely into intermixed β-SiC and free carbon, and consequently the resistivity decreased markedly. Deep voids were formed at the surface of fiber-A as a result of rapid dehydrogenation at the earliest stage of high-temperature exposure. On the other hand, fiber-B, which decomposed mildly, had a dense pore-free structure. The fiber strength was proportional to the reciprocal square root of SiC crystal size. At the same crystal size, the strength of fiber-A was lower because of the surface flaws.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1998.tb02593.x
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  • 3
    Electronic Resource
    Electronic Resource
    Thermal Stability of Low-SiC Fiber (Hi-Nicalon) Treated in a Hot Isostatic Press (1999)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 82 (1999), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The low-oxygen SiC fiber fabricated by the electron-beam irradiation curing method, Hi-Nicalon, was heated at 1773 to 2273 K in a hot isostatic press (800 MPa of argon) and was subsequently reheated at 1873 K at 1 atm (101 kPa) of argon. The hot isostatic press treatment delayed the onset of fiber deterioration to higher temperature. The fiber strength remained almost unchanged by subsequent reheating at 1873 K in 101 kPa of argon. The thermal stability of Hi-Nicalon, as a consequence of the permanent change in surface structure, can be greatly improved by treating in the hot isostatic press.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1999.tb02273.x
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  • 4
    Electronic Resource
    Electronic Resource
    Use of Blended Precursors of Poly(vinylsilane) in Polycarbosilane for Silicon Carbide Fiber Synthesis with Radiation Curing (1999)
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 82 (1999), S. 0 
    Details
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Blended organosilicon precursors containing 10 or 20% of poly(vinylsilane) (PVS) in polycarbosilane (PCS) were prepared and shaped into fiber form by melt-spinning. The influence of PVS addition on the spinning, radiation-curing, and pyrolysis processes was investigated. The addition of PVS increased the spinability of the precursor melt and increased the oxidation sensitivity of the precursor. By adjusting the precursor compositions and the radiation conditions, highly heat-resistant silicon carbide fibers were obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1151-2916.1999.tb01871.x
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  • 5
    Electronic Resource
    Electronic Resource
    Application of radiation curing in the preparation of polycarbosilane-derived SiC fibers (1992)
    Springer
    Journal of inorganic and organometallic polymers and materials 2 (1992), S. 171-179 
    Details
    ISSN: 1572-8870
    Keywords: Preceramic polymer ; polycarbosilane ; radiation curing ; cross-linking ; SiC fiber
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Polycarbosilane fibers were irradiated by gamma-rays under vacuum and by electron beam in He gas flow or under vacuum at room temperature. Free radicals on Si and C atoms were produced. Most radicals reacted with each other, causing cross-links between polycarbosilane molecules. Some radicals, which did not contribute to cross-linking, were fairly stable under vacuum or in inert gas at room temperature but oxidized on exposure to air. The number of stable radicals under vacuum could be decreased by annealing. The remaining radical concentration was about 1% after annealing at 513 K. By a combination of radiation curing and annealing, SiC fibers with smaller quantities of oxygen were prepared. The mechanical properties of the SiC fibers showed a high tensile strength of 2.5 GPa after heat treatment at 1773 K. On the other hand, polycarbosilane fibers could be cured by radiation oxidation at room temperature, that is, gamma-ray or electron irradiation in oxygen, and the oxygen content could be well controlled by irradiation dose and dose rate. The SiC fibers obtained by the radiation oxidation had an oxygen gradient from the surface to the center which was dependent on the radiation oxidation conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00696544
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  • 6
    Electronic Resource
    Electronic Resource
    Electron-beam irradiation effects on mechanical properties of PEEK/CF composite (1989)
    Springer
    Journal of materials science 24 (1989), S. 1570-1574 
    Details
    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 Carbon fibre-reinforced composite (PEEK/CF) using polyarylether-ether-ketone (PEEK) as a matrix material was prepared and electron-beam irradiation effects on the mechanical properties at low and high temperatures were studied. The flexural strength and modulus of the unirradiated PEEK/CF were almost the same as those of carbon fibre-reinforced composites with epoxide resin. The mechanical properties at room temperature were little affected by irradiation up to 180 MGy, but in the test at 77 K the strength of the specimens irradiated over 100 MGy were slightly decreased. The mechanical properties of the unirradiated specimen decreased with increasing testing temperature, but the high-temperature properties were improved by irradiation, i.e. the strength measured at 413 K for the specimen irradiated with 120 MGy almost reached the value for the unirradiated specimen measured at room temperature. It was apparent from the viscoelastic measurement that the improvement of mechanical properties at high temperature resulted from the high-temperature shift of the glass transition of the matrix PEEK caused by radiation-induced cross-linking.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01105672
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  • 7
    Electronic Resource
    Electronic Resource
    Relationship between the 77K mechanical properties of glass/epoxy composite and the glass transition temperature of the matrix resin (1988)
    Springer
    Journal of materials science 7 (1988), S. 973-975 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00720746
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  • 8
    Electronic Resource
    Electronic Resource
    ESR study on chemical crosslinking reaction mechanisms of polyethylene using a chemical agent (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 279-284 
    Details
    ISSN: 0887-624X
    Keywords: polyethylene ; dicumyl-peroxide ; crosslinking ; free radical ; ESR ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction mechanisms of thermal crosslinking of polyethylene with dicumyl peroxide (DCP) at high temperatures were investigated by electron spin resonance (ESR). The crosslinking reactions were induced by the alkyl radicals formed by the thermal decomposition of DCP above 120°C. The kinetics of the free radical reaction were followed during crosslinking reactions at temperatures between 145 and 180°C. © 1997 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    ESR study on chemical crosslinking reaction mechanisms of polyethylene using a chemical agent - II. The effect of phenolic antioxidants (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 2431-2439 
    Details
    ISSN: 0887-624X
    Keywords: polyethylene ; dicumyl-peroxide ; crosslinking ; free radical ; ESR ; antioxidant ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of antioxidant on the reaction mechanism of chemical crosslinking of polyethylene (PE) with dicumyl peroxide (DCP) at high temperatures was investigated by electron spin resonance (ESR). The antioxidant reacts with the alkyl radicals in PE formed by the thermal decomposition of DCP above 120°C, and disturbs the crosslinking. A phenolic type antioxidant produced the phenoxy radical by the reaction with alkyl radicals formed in PE. It is suggested that the selection of a suitable antioxidant for PE crosslinking can be made by ESR analysis. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2431-2439, 1997
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Radiation-induced oxidative degradation of isotactic polypropylene (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 1361-1372 
    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: Gas evolution, oxygen consumption, and change of mechanical properties were studied for the γ-ray irradiation of isotactic polypropylene from 60Co under various conditions, such as vacuum, air, and oxygen at room temperature. For irradiation under vacuum, G(H2) = 2.9 and G (CH4) = 0.09; the G values for other gases were very small. In the presence of oxygen, G(H2) was the same, and the G values for other hydrocarbons were two times those under vacuum. The G values of oxidative products and oxygen consumption were G(CO2) = 2.5, G(CO) = 1.1, and G(O2) = 50 at oxygen pressure of 500 torr and were dependent on oxygen pressure. With irradiation under vacuum at 2-3 Mrad, mechanical properties scarcely changes immediately after irradiation but degrade gradually with storage time in air at room temperature.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1981.070260427
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