Morphology and thermal properties of polyethylenes made by metallocene and Ziegler - Natta catalysts

摘要

The morphology and thermal behavior of high density polyethylene and ethylene-octene copolymers prepared with classical Ziegler-Natta (zHDPE) and metallocene catalysts (mHDPE and mLLDPE) are comparatively discussed. Wide angle X-ray diffraction (WAXD) data at room temperature showed that mHDPE crystals are more perfect with smaller unit cell dimensions and have higher crystalline density and larger crystallite sizes when compared to zHDPEs. In the case of copolymers, the unit cell dimensions did not change significatively when the number of branches was increased.