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  • 1
    Electronic Resource
    Electronic Resource
    Calculation of the glass transition temperatures of polymers. Part I. Homopolymers and copolymers with alkyl side chains (1970)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 555-570 
    Details
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Four equations, relating the glass transition temperatures Tg of homopolymers and copolymers to invariant additive temperature parameters (ATP) associated with their constituent groups, but weighted in different ways, have been applied to the calculation of the Tg of seven series of polymers having alkyl side chains. It is shown that the Tg of the 32 polymers considered may be calculated, within 7°K of the observed values, without the use of interaction coefficients from 15 independent variables, representing summations of the ATP's. The present calculations are confined to those structures which may be formed by a recombination of the structures corresponding to these independent variables. It is an essential feature of the approach that a distinction is made between groups with different nearest neighbors. Alternative methods of calculation are considered. The temperature parameter for a sequence of three or more methylene groups is estimated as 141°K, in conformity with the transition in polyethylene at 148°K. Nearest-neighbor interactions, stereoregularity, and crystallinity effects are discussed.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1970.160080407
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  • 2
    Electronic Resource
    Electronic Resource
    The preparation and characterization of new polyether ketone-tetraethylorthosilicate hybrid glasses by the sol-gel method (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 40 (1990), S. 1177-1194 
    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: In recent years, tetraethyl orthosilicate (TEOS) has been used as a precursor in preparing inorganic glasses. The technique, known as the sol-gel process involves a two step poly(hydrolysis-condensation)reaction sequence. The work presented here is concerned with the utilization of a suitably functionalized oligomeric “glassy” organic polymeric component in this two step sequence. In particular, an amine terminated amorphous poly(arylene ether) ketone, (PEK), end capped with isocyantonropyl triethoxy silane was used to synthesize a hybrid network with TEOS. Low incorporation of the PEK oligomers into the network caused by early vitrification can be eliminated by carrying out reactions at elevated temperatures. A systematic change in mechanical and physical properties of the hybrid glass has been found with TEOS content and the annealing temperatures. A model for the network has been proposed based on structural and morphological evidence.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070400709
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  • 3
    Electronic Resource
    Electronic Resource
    Physical characteristics of Ti-6Al-4V implants fabricated by electrodischarge compaction (1991)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 25 (1991), S. 1417-1429 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Physical characteristics of a Ti-6Al-4V implant were evaluated following fabrication using a new electrodischarge compaction technique. Ti-6Al-4V atomized powders were loaded into Pyrex tubes (3.3 mm ID) and subjected to a highvoltage, high-current-density pulse in air for a period of less than 300 μs. Single pulses (1.0, 1.5, 2.0 and 2.5 KJ/grampowder) were applied from a capacitor bank (240, 480 or 720 μF) to produce solid core implants with porous surface layers. Implants were evaluated microscopically for core size, neck size, pore size, grain structure, and incorporated oxide film. Hardness was also evaluated. Implants were compared with Ti-6Al-4V commercial powders. Core size increased and pore size decreased with increases in energy and capacitance. The cores were composed of equiaxed grains which were free of oxide at the grain boundary. Porous layers, consisting of particles connected in three dimensions by necks, were free of oxide films at the connecting interfaces. Neck size increased with increases in input energy and capacitance. Hardness readings of the core, necks, and porous particles resulted in readings higher than or similar to control materials. Electrodischarge compaction did not alter the physical characteristics during compaction.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820251202
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