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  • 1
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 34 (1994), S. 141-152 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 ultra-high strength/modulus, extended chain polyethylene fiber (Spectra® fiber) composite has shown great potential as a lightweight armor material with its extraordinary capability of absorbing the kinetic energy of projectiles. But the relatively low melting point of this fiber (∼ 145°C) has caused concerns regarding the effect of temperature rise during the impact/penetration process on the performance as armor material. In this article, an analysis of temperature rise in projectile and the fiber composite during the impact/penetration process is described. Combining the simulation of impact deformation by finite element analysis and the simulation of temperature rise by a finite difference approximation of the related dynamic equations, the temperature rise caused by the projectile/composite interaction was estimated. Results show that there is a significant temperature rise at the projectile/composite interface due to the friction but that the short length of time involved in the process and the low thermal conductivity of Spectra fiber composite keep the temperature rise in a very small region (in the order of 0.001 cm) around the interface during the impact/penetration process. Consequently, the volume that is affected by the temperature rise is very small, in the order of total 0.001 cm3 around the projectile, and this is too small to generate any detectable effect on the armor performance. After the projectile is stopped, however, substantial heating of fiber composite can occur under specific conditions as the result of heat flow from the hot projectile embedded in the composite. This heating of fibers, however, is a postmortem effect and hence inconsequential to the ballistic performance of the composite armor.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 5 (1994), S. 293-306 
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Strain transfer near hydroxyapatite (HA) coated canine hip implants was examined using simulated anatomical loading based on in vivo strain measurements. Strain changes near implants relative to intact control values were in excess of 100% for transverse and principal strains for zero time period (immediate postimplant) specimens. They were generally smaller (100% or less) for axial, transverse, and principal minimums in the same locations for 4 months postimplantation specimens.Cortical bone loss occurred in all implanted femora. The most extensive loss, up to 47%, occurred adjacent to the proximal section of the implant. Extensive trabecular bone formation, over 300% in some regions of each femur, was noted in all implanted femora.Backscattered electron imaging along the HA-coated sections of the implants showed extensive bone bonded to the coating. Normal light and UV light micrographs showed direct bone apposition to the implant surfaces and extensive bone formation in all test animals. Microscopy revealed no evidence of any soft tissue layer between the implant and bone. Bone was typically found in direct contact with the implant surface.Histomorphometry indicated that bone formation rates in the implanted femora were elevated, up to 850%, relative to controls. Fewer formation sites were noted on the posterior and lateral (in two cases zero sites). Mineral apposition rates (MAR) from two of the dogs were slightly elevated (from 110-113%) in the implanted femora relative to controls and depressed (to about 83% of controls) in a third. © 1994 John Wiley & Sons, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 3
    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: Hydrocarbon-soluble oligomers were prepared by the acid-catalyzed condensation of alkylanilines with formaldehyde. Highest molecular weight oligomers (MW ∼ 6000) were obtained from alkylanilines prepared by the Friedel-Crafts alkylation of aniline with α-olefins. By NMR, it was shown that the oligomers contain structures corresponding to methylene-linked aromatic rings and methylene linked to both an aromatic ring and a nitrogen atom. The oligomers exhibit very good initial inhibition of metal corrosion in aqueous environment; and the inhibition is more persistent than that observed with monomeric analogs.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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