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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Macromolecules 25 (1992), S. 2509-2512 
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The hardening of lamellar polyethylene (PE) as a consequence of a controlled chlorosulfonation treatment has been studied using the microindentation technique. The hardness of the polymer turns out to be a linear function of the density of treated PE. The rate of increase is larger for samples with higher crystallinity. This increase is related to the hardening of crystal lamellae due to the surface attachment of electron dense groups. The latter impede the slippage of crystals and substantially reduce the rate of creep of the material under the contact pressure applied.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary A combined X-ray diffraction and DSC investigation of the crystalline phase in lamellar low density polyethylene after conventional chlorosulfonation treatment has been carried out. Our results indicate that the acid attack does not involve any heavy group penetration within the lattice. The location of these groups at the basal crystal surface contributes, however, to an enhancement of the melting temperature of the modified lamellae. It turns out that the destruction level of crystalline material at 45°C, after 15–20 h is of the order of 20% and progressively increases for longer periods of time.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Polymer bulletin 3 (1980), S. 7-12 
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary New small angle X-ray diffraction data of a series of mostly low density PE samples isothermally crystallized from the melt are reported to discern between the existing ambiguities concerning the alternative of one or two lamellar periodicities. The ratio of X-ray spacings turns out to be dependent on the supercooling of the samples. This result together with the analysis of the 1st and 2nd diffraction peaks during and after heat treatments reveals that the two scattering maxima in the samples investigated most probably originate from the coexistence of two different lamellar periodicities.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 261 (1983), S. 412-416 
    ISSN: 1435-1536
    Keywords: Lamellar structure ; low density polyethylene ; chlorosulfonation ; small angle X-ray diffraction ; electronmicroscopy
    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 investigation of representative details in the lamellar microstructure of LDPE observed after controlled chlorosulfonation using both EM and SAXD is reported. For this purpose melt crystallized PE with two branch contents (ε=0.28 and 2.53 branches per 102CH2) has been prepared using Kanig's technique over a range of temperatures and treatment times. During the first treatment hours the selective incorporation of electron-dense atoms at the lamellar surface produces a macroscopic weight increase, swelling of the sample and a concurrent decrease of the SAXS intensity. The main result, however, is that the thickness of the lamellar structure does not vary with treatment time. After long chlorosulfonation times a saturation of electron-dense atoms within the surface layer and a reduction in the lateral dimensions of the lamellae take place. Optimum conditions for revealing the representative morphology are such as to lead to a weight increase of 50% for PE withε=0.28 of branches and only to an increase of 10% for material of branch content represented by anε value of 2.53.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1435-1536
    Keywords: FerroparaelectricCurie transition ; microhardness ; X-ray diffraction ; polyvinylidene fluoride-trifluorethylene
    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 A combined X-ray diffraction and microhardness investigation of the 70/30 polyvinylidene fluoride-trifluorethylene copolymer was carried out as a function of temperature. The changes in microhardness are interpreted in terms of variations in lattice spacing of the ferro- and paraelectric phases, crystallinity and long period. The changes of microhardness with temperature show four distinct temperature regions. In addition to a low temperature range, in which microhardness decreases exponentially with temperature, the ferroparaelectric Curie transition involves a faster hardness decrease. At higher temperature, the sudden microhardness rise is ascribed primarily to an increase of crystal thickness within the remnant paraelectric phase. Near the melting point, the fusion of thinner crystals leads to a range in which microhardness decreases exponentially again.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0040-6090
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 4 (1985), S. 324-326 
    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
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 23 (1988), S. 862-866 
    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 Microhardness is used to examine the microstructural changes of a series of polyethylene (PE) /polypropylene (PP) blends in a wide composition range. This study complements previous hardness results obtained on high-density/low-density polyethylene systems. The use of isotactic polypropylene, as a blend component allows investigation of a material in which the hardness of the amorphous phase, contrary to PE, differs from zero. The influence of treatments such as crystallization of the PP-phase in the presence of molten PE, within the blend, or annealing the PE phase, while leaving the PP component unmodified, are discussed with reference to the additivity hardness values of the single componentsH PE andH PP. It is shown that the coexistence of the PP and PE phases inhibits the crystallization capability of one phase and modifies the annealing behaviour of the other phase leading, as a result, to depressedH PP andH PE values. The observed deviations ofH blend, throughout the composition range, from the additivity law of single components are quantitatively justified in the light of crystallinity changes of the PP phase and in terms of the population of modified lamellae of the PE component.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 18 (1983), S. 1077-1082 
    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 stress-strain diagrams of a series of melt-crystallized polyethylene samples with a varying number of chain defects have been investigated. The elastic modulus,E, and the surface hardness,MH, markedly decrease with increasing number of defects. The mechanical behaviour of the lamellar structure of PE modulated by a major exclusion of chain defects from the crystals is discussed in the light of Takayanagi's two-phase model. The data suggest thatE is very sensitive to the fraction of tight crystalline bridges between lamellae. The correlation found betweenE andMH emphasizes, in addition, the different and complementary role played by the amorphous layer in each mechanical test. In the former case one measures the elastic deformation of the layer reinforced by tie molecules. In the latter test the plastic deformation under compression of the lamellae sandwiched between noncrystalline layers is contemplated. In both cases the influence of the number of defects drastically affects the nature of the crystalline lamellae and surface layer and consequently substantially modifies both types of properties.
    Type of Medium: Electronic Resource
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