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  • 1
    Electronic Resource
    Electronic Resource
    The limiting size of natural paracrystals (1980)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 13 (1980), S. 521-523 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: X-ray diffraction data for various materials reveal that naturally occurring microparacrystals cannot exceed a certain limiting size. The empirically obtained linear relationship between the square root of the limiting number of lattice planes within a paracrystal and the reciprocal value of the relative distance fluctuation between planes (degree of distortion) is discussed in the light of the paracrystal approach.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889880012708
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  • 2
    Electronic Resource
    Electronic Resource
    Novel aspects of the real paracrystal (1981)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 37 (1981), S. 85-91 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: A revision of the mathematical concept of paracrystals is proposed. Hermann's [Z. Electrochem. (1940), 46, 425-436] early theory of mesophases represents a special case of a paracrystal where the statistical parameters introduced were merely crystalline or gas-like. The theory of paracrystals removes the black-white picture of crystalline and amorphous phases by introducing 18 new statistical parameters into conventional crystallography. It is shown that a real paracrystal can be defined by a three-dimensional convolution polynomial in combination with an empirically derived α* law. Hence, a missing corner-stone of colloid science is established.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739481000156
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  • 3
    Electronic Resource
    Electronic Resource
    Diamagnetism and structure of nitric acid-treated bulk polyethylene (1982)
    Springer
    Polymer bulletin 7 (1982), S. 317-321 
    Details
    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 An alternative procedure to examine the nature of the end product of nitric-acid-treated bulk polyethylene involving the measurement of the diamagnetic susceptibility is reported. This simple non-destructive method complements previous results obtained by means of IR spectroscopy. Thus after selectively removing the surface layer of the polyethylene lamellae with nitric acid (t 〉 50h) the diamagnetic susceptibility substantially decreases to values which are consistent with tilted paraffinic chains terminated by carboxyl groups including -NO2 groups in a 4∶1 ratio.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00256799
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  • 4
    Electronic Resource
    Electronic Resource
    Electrical conductivity in doped polyethylene (1981)
    Springer
    Polymer bulletin 5 (1981), S. 311-316 
    Details
    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 Melt crystallized samples of mostly low density polyethylene were exposed to a bromine atmosphere, at room temperature, for long periods of time (3–30 h). The amount of absorbed halogen within the polymer increases with the increasing fraction of non crystalline material and decreases, while being stored in air, reaching a leveling off value. Concurrently the electrical conductivity is enhanced by several orders of magnitude depending on the proportion of absorbed dopant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00255123
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  • 5
    Electronic Resource
    Electronic Resource
    Influence of chlorosulfonation on the surface mechanical properties of lamellar polyethylene (1983)
    Springer
    Polymer bulletin 10 (1983), S. 553-557 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00285375
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  • 6
    Electronic Resource
    Electronic Resource
    Lamellar structure in melt crystallized low density polyethylene (1984)
    Springer
    Polymer bulletin 12 (1984), S. 269-274 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00275978
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  • 7
    Electronic Resource
    Electronic Resource
    Long periods in melt crystallized polyethylene two coexisting structures? (1980)
    Springer
    Polymer bulletin 3 (1980), S. 7-12 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00263199
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  • 8
    Electronic Resource
    Electronic Resource
    Lamellar structure in melt crystallized low density polyethylene (1983)
    Springer
    Colloid & polymer science 261 (1983), S. 412-416 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01418215
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  • 9
    Electronic Resource
    Electronic Resource
    Comment of the influence of annealing on the distribution of chain defects in drawn polyethylene (1982)
    Springer
    Colloid & polymer science 260 (1982), S. 694-696 
    Details
    ISSN: 1435-1536
    Keywords: Drawn branched polyethylene ; annealing ; unit cell expansion ; crystalline 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 The present study suplements preceding investigations [1–5] concerning the distribution of chain-defects between crystalline regions and crystal surface, and extends them to the influence of annealing in case of drawn branched polyethylene (PE). For this purpose available unit cell data for annealed drawn PE withɛ=3%, at various annealing temperatures and times, are examined by assuming the penetration of chain defects at interstitial crystal sites by means of 2gl kink generation. The analysis of results shows that the initial level of ∼8×10−2 chain defects expanding the lattice decreases linearly as a function of annealing temperature. After annealing at 100 °C during 3×103 min this level decreases to values 〈 10−3. It is suggested that these space-filling point defects can be converted through chain diffusion in “amorphous” defects, “cooperative” defects and/or in defects segregated into the surface layer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01414655
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  • 10
    Electronic Resource
    Electronic Resource
    Degradation of nitric acid-trbeated bulk polyethylene (1983)
    Springer
    Colloid & polymer science 261 (1983), S. 626-630 
    Details
    ISSN: 1435-1536
    Keywords: Low-density polyethylene ; differential scanning-calorimetry ; long period ; fuming nitric acid ; dicarboxylic acids
    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 LDPE samples with differing branching content were treated with fuming nitric acid for times up to 180 h at 60°C. The samples were examined by differential scanning calorimetry and small angle X-ray diffraction. While the crystal thickness derived from the X-ray long period remains practically constant throughout treatment timet, a conspicuous sharpening and shifting of the melting curves to higher temperatures witht is observed. It is suggested that the shift in melting peak is caused by the contribution of the dicarboxylic groups attached to the crystal surface after treatment. It is further shown that the shift depends inversely on the crystal thickness. The comparison of melting points for long time nitric acid treated PE samples with data from dicarboxylic acids has permitted the derivation of an expression for the melting temperature of longer molecular diacids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01415031
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