2008 Volume 55 Issue 2 Pages 56-65
In this study, effect of adding EEBE (ethylene-b-ethylene•buthylene-b-ethylene triblock copolymer) compatibilizer into a series of polyethylene (PE)/polypropylene (PP) blends was investigated in terms of their morphological, mechanical, and viscoelastic properties. Although the neat PE/PP blends showed brittle property, when adding EEBE as a compatibilizer into them, their tensile properties became ductile and, as a result, the elongation at break was over 1000%. From the results of the Charpy impact test, the strength of the PE/PP blends, particularly, in which PE content was more than 30wt%, increased with increasing the amount of the EEBE compatibilizer. The impact strength drastically increased around at −40°C, and the temperature corresponds to the glass-transition temperature (Tg) of EEBE, which is referred to the α dispersion on viscoelestic measurement. The morphology of PE/PP blends stained by ruthenium oxide was observed using scanning electron microscope (SEM). It shows that the size of PP domain, 4.24 μm, decreased to 1.62 μm by adding EEBE. Furthermore, the activation energies of the γ dispersion of PE, the β dispersion of PP, and the α dispersion of EEBE were not changed with PP contents and with/without EEBE, indicating that EEBE mainly influenced the free energy of the surface of PE/PP phase, not the molecular motions of PE and PP phases.
