Polymerization of heterophasic propylene copolymer with Me2Si(2-Me-4-PhInd)2ZrCl2 supported on SiO2 and SiO2-MgCl2 carriers

Abstract

Me2Si(2-Me-4-pbind)2ZrCl2 supported on SiO2/MgCl2 binary support was prepared for the preparation of heterophasic copolymer of polypropylene. The bi-support underwent surface treatment with various alkyl aluminum compounds such as trimethylaluminum (TMA), triethylaluminum (TEAL), and triisobutylaluminum (TIBA) before supporting the metallocene catalyst for 3 or 24 hours and were used for homopolymerization. It was notable that the generated SiO2/MgCl2 bi-support had lower surface area, pore volume and size as compared to the conventional SiO2. Impact polypropylene copolymers (IPCs) were obtained using two-step polymerization in one reactor with the presence of metallocene catalyst supported on SiO2. Propylene was polymerized in the reactor to produce the iPP matrix followed by polymerization of ethylene resulting to heterophasic material. It is apparent that the molecular weight of the polymer increased with longer PE polymerization time and as the polymerization time was more than 40 min, PP peak appeared near 147.9–149.2 °C, and a new peak emerged at 116.9–119.9 °C which could be attributed to the melting temperature of iPP crystallites and a less intense peak to either chains of ethylene-propylene copolymers. SEM images also confirmed that spherical PE particles were deeply embedded in the crystalline PP matrix and a large amount was produced as the polymerization time of the second stage ethylene polymerization was increased.