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  • 1
    Electronic Resource
    Electronic Resource
    New aspects of the microstructure of polyethylene-isotactic polypropylene gel blends as revealed by microhardness: influence of composition (1990)
    s.l. : American Chemical Society
    Macromolecules 23 (1990), S. 5352-5355 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00228a008
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Novel aspects in the structure of poly(ethylene terephthalate) as revealed by means of small angle x-ray scattering (1991)
    s.l. : American Chemical Society
    Macromolecules 24 (1991), S. 5980-5990 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00022a013
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  • 3
    Electronic Resource
    Electronic Resource
    Temperature dependence of microhardness and structure of ferroelectric copolymers of vinylidene fluoride (1992)
    Springer
    Journal of materials science 27 (1992), S. 2124-2130 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Measurement of the microhardness (H) and X-ray investigation of melt-crystallized random copolymers of vinylidene fluoride with trifluorethylene containing 60 to 80 mol% VF2 were carried out as a function of temperature. The results show that (i) at a given temperatureH rapidly increases with VF2 content; (ii) the Curie transition was found to involve an inflection point in the exponential temperature dependence of hardness; and (iii) at the Curie temperature (T c) the ferroelectric crystals undergo reversibly a solid-state transformation, followed by the microhardness, to a non-polar (paraelectric) state showing a faster hardness decrease with increasing temperature aboveT c. Changes inH with VF2 content and temperature are discussed in the light of the lattice spacings of the ferro- and paraelectric phases and crystallinity values. The application of a relationship to account for correlations between mechanical properties and microstructure is considered.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01117926
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  • 4
    Electronic Resource
    Electronic Resource
    Mechanical properties and structure of glassy and semicrystalline random copolymers of poly(ethylene terephthalate) and poly(ethylene naphthalene-2,6-dicarboxilate) (1992)
    Springer
    Journal of materials science 27 (1992), S. 2161-2164 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The microhardness,H, of random copolymers of poly(ethylene terephthalate) (PET) and poly(ethylene naphthalene-2,6-dicarboxilate) (PEN) was determined over a wide range of compositions. It is shown that microhardness of the materials is strongly affected by the composition. The mechanical property,H, of the quenched amorphous copolyester films is discussed in terms of a simple model given by the additivity values of the single componentsH a PET andH a PEN . In materials containing up to 30% PEN, crystals of PET are found after annealing at temperatures 10 °C below their melting points. In materials containing ∼ 80% PEN, after annealing at about 20 °C below the melting point, crystals of PEN are formed. The observed deviation ofH for the crystallized films from the additive behaviour of the single components can be quantitatively related to two factors: the changes occurring in the crystallinity value and in the thickness of PET and PEN crystals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01117931
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  • 5
    Electronic Resource
    Electronic Resource
    Mechanical study of poly(vinylidene fluoride)-poly(methyl methacrylate) amorphous blends (1991)
    Springer
    Journal of materials science 26 (1991), S. 2579-2582 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Amorphous films of poly(vinylidene fluoride)-poly (methyl methacrylate) were prepared by initial precipitation from a solvent and rapid solidification at ≈ 15 °C from the molten state. The PVDF/PMMA compositions studied were 25/75, 45/55, 50/50, 55/45, 60/40 and 75/25. X-ray scattering analysis suggests that mixture of the two components throughout the composition range studied occurs at a molecular level. The parallel decrease of the microhardness, which obeys a simple expression: H blend = H PMMA (1−φ) (φ being the PVDF concentration) and the glass transition temperature, T g, following the predictions, of Gordon and Taylor, reveals that the depression of microhardness is caused by the shift of T g towards lower temperatures. It is pointed out that the effect of PVDF molecules is to act as a softening agent within the PMMA component.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00545538
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  • 6
    Electronic Resource
    Electronic Resource
    Mechanical anisotropy and orientation of injection moulded poly(ethylene terephthalate) (1993)
    Springer
    Journal of materials science 12 (1993), S. 1140-1143 
    Details
    ISSN: 1573-4811
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00420547
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  • 7
    Electronic Resource
    Electronic Resource
    Microhardness and surface free energy in linear polyethylene: The role of entanglements (1990)
    Springer
    Colloid & polymer science 268 (1990), S. 440-446 
    Details
    ISSN: 1435-1536
    Keywords: Microhardness ; polyethylene ; molecularweight ; folded-chainlamellae ; melting ; surfacefreeenergy ; entanglements
    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 microhardness of a series of melt crystallized samples of linear polyehtylene was investigated in a wide range of molecular weights. The x-ray long period was analyzed to study the variation of the hardness-derived constantb as a function of molecular weight (M η). It is pointed out thatb offers a measure of the hardness depression due to the finite thickness of the lamellar crystals. The data obtained show that the increase and final leveling-off (forM η 200 000) ofb withM η parallels the concurrent increase of the surface free energy, as derived from DSC experiments. Results are discussed using the concept og chain folded lamellae as thermodynamically stable non-homogeneous microphases. Comparison of experimental and calculated data supports the view that the number of molecular entanglements, segregated onto the defective surface boundary of the heterogeneous crystals influence the shearing mechanism within the “mesocrystals” and thereby control the yield behavior of the material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01411002
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  • 8
    Electronic Resource
    Electronic Resource
    Study of blends based on recycled polyethylene wastes (1994)
    Springer
    Journal of materials science 29 (1994), S. 1109-1114 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Data covering the physical properties of molten and solid samples of two binary blends of recycled polyethylene wastes, in a wide range of compositions, are reported. While some properties (density, fusion enthalpy) show a linear behaviour with composition other properties (microhardness, yield stress) show a deviation from linearity. Deviation of microhardness additivity of the single components has been interpreted, after analysis of the DSC thermograms, as being due to segregation and recombination of molecular species from both components during crystallization. It is also suggested that the presence of a high oxidation in one low-density polyethylene component, detected by infrared spectroscopy, influences the very low values observed for the melt flow index and melt elongation at break.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00351439
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  • 9
    Electronic Resource
    Electronic Resource
    Mechanical study of poly(vinylidene fluoride)-poly(methyl methacrylate) amorphous blends (1991)
    Springer
    Journal of materials science 26 (1991), S. 2579-2582 
    Details
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Amorphous films of poly(vinylidene fluoride)-poly (methyl methacrylate) were prepared by initial precipitation from a solvent and rapid solidification at ≈ 15 °C from the molten state. The PVDF/PMMA compositions studied were 25/75, 45/55, 50/50, 55/45, 60/40 and 75/25. X-ray scattering analysis suggests that mixture of the two components throughout the composition range studied occurs at a molecular level. The parallel decrease of the microhardness, which obeys a simple expression:H blend =H PMMA (1−φ) (φ being the PVDF concentration) and the glass transition temperature,T g, following the predictions, of Gordon and Taylor, reveals that the depression of microhardness is caused by the shift ofT g towards lower temperatures. It is pointed out that the effect of PVDF molecules is to act as a softening agent within the PMMA component.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02387720
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  • 10
    Electronic Resource
    Electronic Resource
    Double ferroelectric-to-paraelectric transition in 70/30 vinylidene fluoride-trifluoro ethylene copolymer as revealed by dielectric spectroscopy (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 1449-1455 
    Details
    ISSN: 0887-6266
    Keywords: ferroelectric copolymers ; curie temperature ; dielectric relaxation ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The variation of dielectric properties with temperature in the 1 kHz to 1 GHz frequency range for the 70/30 copolymer of vinylidene fluoride with trifluoroethylene has been associated to two processes: the β relaxation process associated with the glass transition of the amorphous phase and the ferroelectric-to-paraelectric crystal transition. The β process follows a Vogel-Fülcher behavior exhibiting an anomaly in the vicinity of the crystal transition. Analysis of the ferroelectric-to-paraelectric Curie transition reveals the existence of a double relaxation maximum in the dielectric losses. Results have been interpreted in terms of the Havriliak-Negami relaxation function. The variation of the relaxation strength and of the broadening parameter has been investigated as a function of temperature. The obtained results are discussed in terms of a two-step phase transformation mechanism for the Curie transition: a first transition from the low temperature “all-trans” ferroelectric phase to a more defective phase; a second transition from the latter phase to the final paraelectric structure. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1994.090320816
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