Polypropylene Made with In-Situ Supported Me₂Si(Ind)₂ZrCl₂ and Me₂Si(2-Me-Ind)₂ZrCl₂ Catalysts: Properties Comparison

Summary: Propylene homopolymerizations were carried out using Me₂Si(Ind)₂ZrCl₂ and Me₂Si(2-Me-Ind)₂ZrCl₂, MAO-modified silica, and common alkylaluminum cocatalysts. Supported catalysts were prepared by the in-situ immobilization technique. The effect of the type and concentration of alkylaluminum on propylene polymerization was evaluated using TEA (triethylaluminum), IPRA (isoprenylaluminum), and TIBA (triisobutylaluminum) as cocatalysts. The polymers were analyzed by gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and scanning electronic microscopy (SEM). The effect of the type and concentration of alkylaluminum on the melting temperature and the molar mass of the polypropylene was the same for both catalysts. The polymers made with in-situ supported catalyst had lower melting points and, in almost all polymerization conditions, higher molar masses than those produced by homogeneous polymerization. Polypropylene samples made with Me₂Si(2-Me-Ind)₂ZrCl₂ had higher melting temperatures and molar masses than those made with Me₂Si(Ind)₂ZrCl₂. SEM micrographs showed that the polymers obtained with in-situ supported systems had a well-defined morphology, confirming that the polymerization indeed took place onto the silica support.

SEM micrographs of polypropylene particles obtained with Me₂Si(2-Me-Ind)₂ZrCl₂ in the presence of IPRA.