Propylene Polymerization over MgCl2‐Supported Ziegler–Natta Catalysts Containing Tri‐Ether as the Internal Donor

Abstract

ABSTRACT1‐Methoxy‐2,2‐bis(methoxymethyl)butane as a new internal donor was synthesized by the reaction of 1,1,1‐tris(hydroxymethyl)propane with sodium hydride as the base and methyl iodide as the alkyl halide. The tri‐ether compound was characterized by NMR and FTIR techniques. The MgCl2‐supported titanium catalysts were incorporated with varying amounts of 1‐methoxy‐2,2‐bis(methoxymethyl)butane as the internal donor (ID) and also without the internal donor were synthesized, and then the prepared catalysts were characterized. The concentration of titanium, magnesium, and chloride were determined by spectrophotometry and by complexometric and argentometric titration, respectively. The polymerization of propylene was carried out with the prepared catalysts in conjunction with triethylaluminum as a cocatalyst and hydrogen as a chain transfer agent, with and without cyclohexylmethyldimethoxysilane as the external donor. The effects of a new internal donor on MgCl2‐supported Ziegler–Natta catalysts for propylene polymerization were investigated, and then these results were compared to the obtained polypropylenes results, which were obtained using the conventional Ziegler–Natta catalyst containing diisobutyl phthalate as the internal donor. The highest isotacticity, melting temperature, and crystallinity degree of polypropylene were obtained using Cat‐D with an ID/Mg molar ratio equal to 0.44, and the highest catalytic activity is related to Cat‐B with an ID/Mg molar ratio equal to 0.22.The Ziegler–Natta catalysts incorporated with various ID/Mg molar ratios of 1‐methoxy‐2,2‐bis(methoxymethyl)butane were synthesized. The polymerization of propylene was carried out with the prepared catalysts. The highest catalytic activity is related to Cat‐B with an ID/Mg molar ratio equal to 0.22. The catalyst with an optimum ID/Mg molar ratio equal to 0.44 is a favorable catalyst for polymerization of propylene.