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  • 1995-1999  (5)
  • 1945-1949
  • polymer blends  (3)
  • conservation  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Plant communities and conservation of Botrychium-rich grasslands in the Bitcherland (Northern Vosges Biosphere Reserve, France) (1999)
    Springer
    Biodiversity and conservation 8 (1999), S. 1519-1532 
    Details
    ISSN: 1572-9710
    Keywords: Botrychium ; Pteridophyte ; grassland ; conservation ; plant community
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Two species of Botrychium are present in the Bitcherland grasslands, B. lunaria and B. matricariifolium, and both are protected in this territory. They occur in five different continental grassland communities, (i) a dune grassland (Diantho-Armerietum), (ii) a mesotrophic sandy grassland (Viscario-Avenetum), composed of three sub-units, therophitic ( V.A. airetosum), meso-eutrophic (V.A. saxifragetosum) and acidic (V.A. violetosum caninae), and (iii) an oligotrophic sandy grassland (Aveno-Genistetum). Both species of Botrychium appear in the three sub-units of Viscario-Avenetum, but only one in Diantho-Armerietum (B. matricariifolium) and in Aveno-Genistetum (B. lunaria). These Botrychium species are present in quite similar habitats in other lowland areas in Central Europe. The conservation of these threatened species, sensitive to plant competition, requires the maintenance or restoration of extensive agricultural management with late cutting and no fertilization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008988709046
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Phytosociology and conservation of Carex hordeistichos Vill. in the Lorraine region (France) (1999)
    Springer
    Biodiversity and conservation 8 (1999), S. 1435-1445 
    Details
    ISSN: 1572-9710
    Keywords: clay ; conservation ; pasture ; phytosociology ; ruderal plant ; trampling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Carex hordeistichos is a peri-Mediterranean species, which is rare over all its distribution range. In Lorraine (France), where the field investigations were conducted, as in other Western European areas, it is present only in secondary habitats, constituted of heavily trampled wet pastures and vehicle tracks on clayed soils. All plant communities with Carex hordeistichos described from Western European areas can be linked to the Carici hordeistichi-Trifolietum fragiferi association, classified in the Agropyro-Rumicion wet pasture alliance. The conservation of this threatened ruderal plant requires the maintenance of a high disturbance level through grazing, trampling and soil packing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008956506479
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Drop deformation during elongational flow in blends of viscoelastic fluids. Small deformation theory and comparison with experimental results (1995)
    Springer
    Rheologica acta 34 (1995), S. 525-533 
    Details
    ISSN: 1435-1528
    Keywords: Emulsion model ; polymer blends ; drop deformation ; elongational flow ; viscoelasticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The deformation of dispersed droplets in immiscible polymer blends was studied in elongational flow, with an original method based on quenching specimens elongated in the melt. Results for high capillary numbers and different viscosity ratios were compared to the linear theory of viscoelastic emulsions of Palierne. Simple expressions for the drop deformation could be obtained for Maxwell fluids, and the influence of viscoelasticity of matrix and inclusions on the drop deformation process was discussed. With respect to the Newtonian approximation, the description of some experimental data could be improved. However, the predictions of the viscoelastic model appeared to be very sensitive to the choice of relaxation times.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00712313
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  • 4
    Electronic Resource
    Electronic Resource
    Rheology/morphology/flow conditions relationships for polymethylmethacrylate/rubber blend (1996)
    Springer
    Rheologica acta 35 (1996), S. 369-381 
    Details
    ISSN: 1435-1528
    Keywords: Melt rheology ; linear and non-linear viscoelasticity ; polymer blends ; reinforced polymers ; morphology ; Cox-Merz rule ; aggregation ; percolation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Viscoelastic behavior, phase morphology and flow conditions relationships in polymer/rubber blends have been investigated. The importance of such correlations is illustrated on polymethylmethacrylate (PMMA)/rubber blends subjected to different flow conditions both under small and large deformations. In small-amplitude oscillatory shear (the morphology does not change during the flow) the elastic modulus G′ of the concentrated blends shows a secondary plateau, G′ p , in the low frequency region. This solid-like behavior appears for rubber particle contents beyond the percolation threshold concentration (15%). Morphological observations revealed that for concentrations higher than 15%, the particles are dispersed in a three-dimensional network-type structure. In capillary flow it was found that the network-type structure was destroyed and replaced by an alignment of particles in the flow direction. This morphological modification resulted in a decrease in both viscosity and post-extrusion swell of the blends. Morphological observations revealed that the ordered structure in the flow direction was concentrated only in the skin region of the extrudate, where the shear stress is higher than the secondary plateau, G′ p . A simple kinetic mechanism is proposed to explain the observed morphology. Similarly, steady shear measurements performed in the cone-and-plate geometry revealed alignment of particles in the flow direction for shear stress values higher than G′p.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00403538
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  • 5
    Electronic Resource
    Electronic Resource
    Relationship between structure and rheological properties in the melt of polymers containing spherical inclusions (1995)
    New York, NY : Wiley-Blackwell
    Polymers for Advanced Technologies 6 (1995), S. 301-308 
    Details
    ISSN: 1042-7147
    Keywords: polymer blends ; melt rheology ; crosslinked rubber ; structured latex ; 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: The linear viscoelastic behavior of model rubbertoughened polymer melts has been studied. The most significant influence of the dispersed crosslinked rubber phase on the melt rheology of the blends is the existence of a secondary plateau for the storage modulus G′ at low frequencies. This behavior was ascribed to a percolation phenomenon, leading to the formation of a threedimensional network of inclusions, and contributing to the elasticity at low frequencies of the blend. Two different systems were investigated: (a) a polystyrene matrix with crosslinked and structured latex particles and (b) silicon oil matrices with homogeneous crosslinked PMMA particles. An initial shearing history was found to influence the dynamic mechanical properties of the molten blends and in particular to lower the lowfrequency plateau value for G′. During a subsequent annealing, the plateau modulus increases again. These results are in agreement with the assumption of a particle network.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pat.1995.220060508
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    Paper (German National Licenses)
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