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  • 1
    Electronic Resource
    Electronic Resource
    Equilibrium and non-equilibrium melting of branched polyethylene relating to defect incorporation within crystals (1987)
    Springer
    Colloid & polymer science 265 (1987), S. 239-245 
    Details
    ISSN: 1435-1536
    Keywords: Branchedpolyethylene ; equilibriummelting point ; enthalpy offusion ; surface free energy ; kinks ; chain defects
    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 New equilibrium melting point data, for polyethylene containing chain defects, are tested in the light of random copolymer predictions. A simplified expression for the melting point depression of random copolymers containing small amounts of non-crystallizable units is derived. Non-equilibrium melting data for rapidly quenched polyethylene samples are also reported. The fusion enthalpyΔH∘(X), and the surface free energyσ e for crystals containing defects are evaluated using crystallinity, equilibrium meltingtemperatures and X-ray long period data. It is shown that increasing defect penetration within crystals induces a decrease ofΔH∘(X) withX in accordance with theoretical predictions. Finallyσ e is, similarly, shown to decrease with increasing number of chain defects attached to the crystal surface.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01412713
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Dielectric relaxation of poly(ester-ether-carbonate) multiblock terpolymers (1995)
    Springer
    Colloid & polymer science 273 (1995), S. 58-65 
    Details
    ISSN: 1435-1536
    Keywords: Dielectric relaxation ; block copolymers ; termoplastic elastomers
    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 The dielectric properties of a series of poly(ester-ether-carbonate) multiblock terpolymers have been investigated as a function of ether and carbonate composition in the frequency range of 103–106 Hz. The degree of polymerization of the samples was determined by viscosimetry measurements. The weight fraction, degree of crystallinity, and melting temperatures were characterized by means of x-ray diffraction and DSC methods. Dielectric behavior has been discussed in terms of Havriliak-Negami formulation. The variation of the dielectric properties with temperature has been associated with two relaxation processes: a) the γ-relaxation process observed at low temperature, which is associated to local motion of polar groups attached to both the soft and the hard segments, and b) the β process assigned to long-range molecular motions above the glass transition temperature.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00655675
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Microhardness-structure correlation of iPP/EPR blends: influence of molecular weight and EPR particle content (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 786-793 
    Details
    ISSN: 1435-1536
    Keywords: Key words Microhardness ; poly(propylene) ; ethylene-co-propylene rubber ; blends ; surface free energy
    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 The influence of molecular weight on the mechanical properties of isotactic poly(propylene) (iPP) and iPP blended with ethylene-propylene copolymers has been investigated by means of the microhardness technique. The hardness (H) of iPP is shown to slightly decrease with increasing molecular mass, within the range of molecular weights investigated. The H-decrease is correlated to a loss of crystallinity as the average molecular weight increases. On annealing, the mechanical properties are enhanced as a consequence of an increase in both, the degree of crystallinity and the crystalline lamellar thickness. A value of H ∞ c for iPP crystals of infinite thickness in the α-form is proposed for the first time. The inclusion of EPR particles in the iPP matrix softens the material. This result could be explained in terms of an increase in the basal surface free energy of the iPP crystals with increasing amount of rubber content.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050311
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    Paper (German National Licenses)
    Fulltext
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