TIT# Mechanical Properties and the Two-Phase Structure Inside the
     Heterophase Domains of Blends from HDPE and SBS Star Block Copolymers
AUT# Stribeck, N.; Reimers, C.; Ghioca, P.; Buzdugan, E.
SOU# J. Polym. Sci., Part B: Polym. Phys. (1998), 36, 1423-1432
LOC# xv030 @selbst.ftx
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ABS# Blends from polyethylene (PE) and polystyrene-b-polybutadiene-b-polystyrene
     star block copolymers (SBS) (thermoplastic elastomers) are studied with
     polyolefine recycling in view. Each component, dispersed in a
     heterogeneous blend, exhibits a two-phase morphology. This structure is
     investigated by small-angle X-ray scattering (SAXS) and compared to
     mechanicla properties as a function of SBS grade and content. Increasing
     the SBS content one observes a vanishing PE-related long period
     reflection, while an SBS-related peak emerges. Best mechanical properties
     are obtained at concentrations, where the width of the observed long
     long period reflection is broadest. For a quantitative analysis of the
     SAXS, the interface distribution function (IDF) analysis is employed.
     Data are fitted wit a function modeling arrangement as well as disorder
     of domains inside the two different kinds of dispersed grains. The
     analysis yields that the observed broadening of the long spacing peak is
     caused only by an increased fluctuation of the thicknesses of the
     amorphous layers in the PE stacks. This fluctuation again decreases for
     SBS concentrations beyond 15 wt-%. The effect is strongest for blends
     containing the SBS grade with the lowest molecular weight and is
     discussed in terms of its compatibilization effect.