Mechanical properties and crystallization behavior of high fluidity polypropylene/metallocene poly(ethylene-butene-hexene) copolymer blends

This article presents a study on blends of high fluid polypropylene (HF-PP)/metallocene poly(ethylene-butane-hexene) copolymer (mEBHC) prepared by melt-blending process using a twin-screw extruder. Six different mass fractions of mEBHC in the blends: 0, 5, 10, 30%, and 100% were investigated in our study. The thermal behavior, fracture surface morphology, mechanical properties, and rheological properties of the blends were analyzed. Our results suggested that phase separation of HF-PP/mEBHC blends occurred during the cooling process. The addition of 30 wt % mEBHC resulted in a rise of crystallinity of HF-PP/mEBHC blends from 22.8% to 34.9%. The wide-angle X-ray diffraction (WAXD) showed that the incorporation of mEBHC did not have any influence on the intrinsic crystal structure of HF-PP. The droplet-matrix micrographs of the blends given by scanning electron microscope (SEM) revealed that mEBHC particles were dispersed as "droplet" in HF-PP continuous phase. When mEBHC content was increased up to 30%, the impact strength at 23^°C and -20 ^°C of HF-PP/mEBHC blends were improved by 150 and 35%, respectively, while the tensile strength and flexural strength were decreased slightly, compared to pristine HF-PP. The apparent shear viscosities of blends were similar to that of pristine HF-PP.