Melt Mixed Polypropylene/Metallocene Polyethylene Thermoplatic Elastomer Nanocomposites: Part I: Effect of Silane Modification.

Polypropylene/metallocene polyethylene (PP/mPE) thermoplastic elastomer nanocomposites were prepared by a melt blending process. Metallocene polyethylenes grafted with vinyltriethoxy silane (mPE-g-silane) and neat mPE, both premixed with commercial organoclay (20A) to serve as the elastomer domains, were compared to investigate the silane curing effect on the prepared nanocomposites. According to X-ray diffraction and transmission electron microscopy analyses, the mPE-g-silane was of help in facilitating the intercalation and partial exfoliation of clay for PP/mPE-g-silane/clay system. A slight melting temperature depression of mPE and its nanocomposites was observed with the introduction of the silane curing due to the induced imperfect crystals. There was no silane curing effect found on the thermal stability, but the incorporation of clay increased the thermal stabilities. The PP/mPE-g-silane/clay system conferred higher tensile strength and tear strength than that of PP/mPE/clay system, mainly attributed to the better dispersion in the case of PP/mPE-g-silane. In general, the addition of clay gave more positive enhancement to the tensile and tear properties of the PP/mPE-g-silane/clay system in comparison with the PP/mPE/clay system. [ABSTRACT FROM AUTHOR]