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  • Articles  (6)
  • Articles: DFG German National Licenses  (6)
  • 1980-1984  (6)
  • 1975-1979
  • 1983  (6)
  • Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics  (6)
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  • Articles  (6)
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  • 1980-1984  (6)
  • 1975-1979
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  • 1
    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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  • 2
    Electronic Resource
    Electronic Resource
    Selective elimination reaction on PVC with potassium tert-butylate (1983)
    Springer
    Polymer bulletin 10 (1983), S. 206-209 
    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 Three samples of PVC, having different tacticities, were treated with potassium tert-butylate under mild conditions. By means of 13C-NMR measurements, the elimination reaction was demonstrated to occur selectively by a small fraction of isotactic and heterotactic triads. On the other hand, the elimination was shown to give rise to a definite type of polyenes which absorb at 240 nm in the UV-Visible spectrum. The intensity of this band was proved to be higher as the overall isotactic content of the polymer increases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00272225
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  • 3
    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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  • 4
    Electronic Resource
    Electronic Resource
    Correlation of hardness and microstructure in unoriented lamellar polyethylene (1983)
    Springer
    Journal of materials science 18 (1983), S. 1077-1082 
    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 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
    URL: http://dx.doi.org/10.1007/BF00551976
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  • 5
    Electronic Resource
    Electronic Resource
    Factors affecting the mechanical properties of mica-filled polypropylenes (1983)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 23 (1983), S. 766-770 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Water-ground Phlogopite mica (Kemira Siilinjarvi phlogopite) has been evaluated as a reinforcing filler in polypropylene. The major factors which influence the composite strength and modulus include the size, aspect ratio, and uniformity of the mica flakes. Aqueous delamination permits the production of very small flakes (less than 44 microns diameter) with aspect ratios near 50. Such small flakes impart greater tensile and modulus values to polypropylene than larger flakes and the former can also be reprocessed many times without any deterioration of properties. Surface treatment is necessary for adequate dispersion and coupling, particularly with the finely divided mica fillers. Other properties such as the heat-distortion temperature, fracture toughness, and gas permeability are also influenced by the mean size and aspect ratio of the mica filler. Guidelines are presented to indicate the preferred characteristics of mica fillers for optimum performance.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760231403
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  • 6
    Electronic Resource
    Electronic Resource
    Influence of tacticity on thermal degradation of PVC. V. Relation between the nature of labile conformations and the polyene distribution in the degraded polymer (1983)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 28 (1983), S. 33-43 
    Details
    ISSN: 0021-8995
    Keywords: 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 , Physics
    Notes: Four poly(vinyl chloride) (PVC) samples, 1, 2, 3, and 4, were prepared in bulk using 2,2′-azodiisobutyronitrile at 90°C and 60°C and the same initiator together with UV irradiation at 0°C and -50°C, respectively. Fractions were obtained from samples 2,3, and 4 by extracting with acetone, sample 1 being completely soluble in this solvent. The whole PVC's as well as their acetone soluble and insoluble fractions, were characterized by determining the intrinsic viscosity, the osmometric molecular weight, and the tacticity; then they were thermally degraded up to conversion of 0.3% in powder state. The values of degradation rate for both the insoluble fractions and the whole PVC's were in agreement with some prior results on the influence of syndiotactic sequences on propagation step. The soluble fractions proved to be very unstable in comparison with the insoluble, which, despite the lower molecular weight of the former, seems to obey their higher content of isotactic conformations. The fine polyene distribution in the degraded polymers was carried out by UV-visible spectroscopy. The results reveal the occurrence of two different polyene distributions, and allow for the peculiar one of the soluble fractions to be related to polyenes consisting of two sequences of trans conjugated double bonds separated by a single cis double bond. The results clearly shows that there are two mechanisms for initiation of the PVC degradation, depending on whether it occurs by random unstable structures or by the normal GTTG isotactic or TTTG heterotactic triads. Moreover, these two initiation processes are proved to give rise to different types of polyenes, which accounts for the occurrence of two unlike mechanisms of propagation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1983.070280104
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