By dealing CrCl3∙3THF with the corresponding ligands (L1–L5), an array of fluoro-substituted chromium (III) chlorides (Cr1–Cr5) bearing 2-[1-(2,4-dibenzhydryl-6-fluoro- phenylimino)ethyl]-6-[1-(arylimino)ethyl]pyridine (aryl = 2,6-Me2Ph Cr1, 2,6-Et2Ph Cr2, 2,6-iPr2Ph Cr3, 2,4,6-Me3Ph Cr4, 2,6-Et2-4-MePh Cr5) was synthesized in good yield and validated via Fourier Transform Infrared (FT-IR) spectroscopy and elemental analysis. Besides the routine characterizations, the single-crystal X-ray diffraction study revealed the solid-state structures of complexes Cr2 and Cr4 as the distorted-octahedral geometry around the chromium center. Activated by either methylaluminoxane (MAO) or modified methylaluminoxane (MMAO), all the chromium catalysts exhibited high activities toward ethylene polymerization with the MMAO-promoted polymerizations far more productive than with MAO (20.14 × 106 g (PE) mol−1 (Cr) h−1 vs. 10.03 × 106 g (PE) mol−1 (Cr) h−1). In both cases, the resultant polyethylenes were found as highly linear polyethylene waxes with low molecular weights around 1–2 kg mol−1 and narrow molecular weight distribution (MWD range: 1.68–2.25). In general, both the catalytic performance of the ortho-fluorinated chromium complexes and polymer properties have been the subject of a detailed investigation and proved to be highly dependent on the polymerization reaction parameters (including cocatalyst type and amount, reaction temperature, ethylene pressure and run time).
Low Density Linear Polyethylene Reinforced with Alkali and MAPE Treated Fibers from Coffee Pulp
