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  • 1
    Electronic Resource
    Electronic Resource
    Structure transfer from a polymeric melt to the solid state Part III: Influence of knots on structure and mechanical properties of semicrystalline polymers (1994)
    Springer
    Colloid & polymer science 272 (1994), S. 910-932 
    Details
    ISSN: 1435-1536
    Keywords: Polyethylene ; melt spinning ; mechanical properties ; crystallization ; entanglements ; knots
    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 Investigations of the influence of crystallization conditions and molecular weight on mechanical properties of melt spum monofilaments have been carried out in previous studies [1, 2]. The present results emphasize the influence of crystallization upon two classes of molecular entanglements present in the melt: 1) mobile entanglements with short life times; 2) long living knots as a superstructure of the entanglement network. On the other hand, it is shown that the former number of entanglements controls the thickness of the crystalline lamellae. It is pointed out that knots also have a specific influence on morphology. Knots form the amorphous phase of a semicrystalline polymer and are mechanically active. The present model is comparatively discussed in light of Peterlin's plastic deformation model and Kilian's van der Waals Network Theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00658889
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  • 2
    Electronic Resource
    Electronic Resource
    Structure transfer from a polymeric melt to the solid state. Part I: The influence of chain entanglements in linear polyethylene (1991)
    Springer
    Colloid & polymer science 269 (1991), S. 421-432 
    Details
    ISSN: 1435-1536
    Keywords: Melt spinning ; polyethylene ; mechanical properties ; chain entanglements ; network
    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 Melt-spinning experiments were carried out at high quenching rates. Mechanical properties (elongation at break, natural draw ratio, and elastic recovery) have been measured. Significant variations of these quantities were observed when extrusion conditions were changed. This has been attributed to different states of the entanglements within the melt, which are directly transferred into the solid state. This intercorrelation between melt and solid-state properties has been substantiated in the case of rapidly cooled samples, where a poor crystallization on one side and a simultaneous good conservation of melt history on the other side are provoked.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00655878
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Structure transfer from a polymeric melt to the solid state. Part II: Dependence on molecular weight (1992)
    Springer
    Colloid & polymer science 270 (1992), S. 331-348 
    Details
    ISSN: 1435-1536
    Keywords: Melt spinning ; polyethylene ; mechanicalproperties ; entanglements ; knots ; molecular weight
    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 Melt spinning experiments of polyethylene, using a high quenching rate have been carried out. Molecular weight has been varied. From measurements of the mechanical properties of the monofilaments produced it is concluded that melt history influences the solid state behavior. This is reflected in the hypothesis of a transference of knots, preexisting in the melt into the solid state. Measurements of the elastic recovery allow to offer an interpretation, in which this network of knots does not percolate, until a critical value of the molecular weightM c knot≈105 is surpassed. The possible influence of these knots on the mobile entanglements is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00655848
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Real-time X-ray scattering study during heating of oriented injection-molded polyethylene (1991)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 2 (1991), S. 57-61 
    Details
    ISSN: 1042-7147
    Keywords: Orientation ; Injection-molding ; X-ray scattering ; Polyethylene ; 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
    Notes: Highly oriented linear polyethylene was prepared by elongational flow injection molding. The changes in crystal orientation were investigated as a function of temperature by real-time wide-angle X-ray diffraction. Additionally, the influence of molecular weight upon the microstructure and the changes in orientation, during heating near the melting point, and after cooling have been examined. A shish-kebab structure is inferred for the high molecular weight samples (Mw≥105) from SAXS observations, while for samples with Mw〈105 only an oriented lamellar structure is found. Consequently, a higher thermal stability is shown by the higher molecular weight samples. Furthermore, a recovery of crystal orientation on rapid cooling of the samples from the melt is only observed for samples with Mw≥105. The results are discussed in terms of a preferential recrystallization of chain-folded lamellae, on cooling, onto the shish fibrils which survive at high temperature.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1991.220020201
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    Paper (German National Licenses)
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