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  • 1
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 72-75 
    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: A series of rigid polyurethane foams of densities varying from 65 kg/m-3 to 400 kg/m-3 have been tested in compression as a function of rate and temperature. Two yield points are observed, the lower one being associated with the surface layers, the higher with the bulk of the material. The yield points may be predicted to a first approximation for the higher density foam using a model based on the buckling of a thinwalled cylinder.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 943-950 
    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 tensile properties of high and low density polyethylene specimens produced under careful crystallization and annealing procedures have been determined. A morphologically controlled brittle-ductile transition has been observed for high density polyethylene. Although the lamellar thickness appears to determine the transition, a postulate involving molecular fractional on during crystallization as the cause is offered. For ductile materials, dependence of the Young's Modulus on morphology is interpreted using the fiber-composite analogy of Halpin and Kardos. Yield stress varies as modulus and achieves maximum values consistent with estimates of the critical resolved shear stress of polyethylene crystals.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 3
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 869-874 
    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 effect of time of indentation and time of recovery on the Rockwell hardness, of a series of glassy and crystalline polymers has been determined. An analytical technique, based on conventional viscoelastic approaches, has been developed. This technique permits the resolution of the hardness number into its components of permanent deformation, retarded elastic compression, and retarded elastic recovery. Subtraction of components due to retarded elastic response results in hardness numbers dependent only the time-dependent permanent deformation. Extrapolation of this data to zero time results in an absolute or time-independent value of Rockwell hardness, designated Ro.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 4
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 14 (1974), S. 67-71 
    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: A series of rigid polyurethane foams of densities varying from 65 kg/m-3 to 400 kg/m-3 have been tested in compression as a function of rate and temperature. It has been found that a linear relation exists between density and modulus if the data is referred to a constant thermodynamic temperature.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 5
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 18 (1978), S. 299-305 
    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: One of the problems to be considered in the application of the Halpin-Kardos theory to crystalline polymers is the relation of the crystal length to the only related and measurable parameter, spherulite size. The number average crystal length has been computed for various two and three dimensional models for the crystallization process assuming heterogeneous nucleation. It was found that high values of crystallinity are consistent only with lamellae that are stacked in a parallel fashion. For these systems the number average lamellar length is 0.55 of the spherulite radius. Lower crystallinity polymers have an average lamellar length 0.3 to 0.5 of the spherulite radius, the actual value being determined by the radius. For spherulites of radius 1μm or greater, the size of the primary nucleus has no noticeable influence on the average lamellar length.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 444-448 
    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: Low density polyethylene crosslinked by decomposition of dicumyl peroxide shows evidence for two phases being present in the melt in a narrow temperature range just above the melting point. The effect has been studied in detail using differential scanning calorimetry, transmitted light intensity, and wide angle X-ray diffraction studies at 107°C. It is believed that the effect is caused by the presence of relatively low molecular weight molecules which remain as an extractable fraction after crosslinking.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 30 (1990), S. 860-869 
    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: In the development of advanced composite materials, the mechanical behavior of the matrix is of critical importance. The next generation of composite materials will be based on high modulus tough matrices, of which poly(aryl ether ether ketone) [hereinafter, referred to as PEEK] is one of the first crystalline thermoplastics to receive serious attention. As in all crystalline polymers, the matrix is itself a composite material whose properties depend significantly on the crystalline morphology developed during processing. In this contribution, the current understanding of crystallization in PEEK and its influence on mechanical properties is reviewed. Problems yet to be resolved are highlighted.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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