Effect of Modifiers on MgCl۲-Supported Ziegler-Natta Catalyst

Polyolefins, including polyethylene and polypropylene, represent one of the most important families of plastic materials, indispensable in modern life. Achieving optimal properties for these materials is essential, and this depends heavily on advancements in catalyst support and polymerization technology. The production of high-performance catalysts plays a crucial role in improving polymer properties. Recent research has focused on using metal chlorides (Lewis acids) in Ziegler-Natta catalysts to enhance catalytic activity and polymer characteristics. This study introduces a novel precipitation method to prepare the MgCl۲-based support and investigates the modification of the TiCl۴/MgCl۲/EtOH/Surfactant catalyst system with AlCl۳, ZnCl۲ and their combination. The results demonstrate that the combined use of AlCl۳ and ZnCl۲ significantly outperforms the individual modifiers, with the optimal   ratio of ۱۴ yielding the highest activity (۲۴-۲۶ kg PE/g cat.). Differential scanning calorimetry (DSC) analysis revealed that the thermal properties, including melting temperature (۱۳۵.۷ ℃) and crystallinity (۵۶.۵%), remain largely unaffected by the modification. Additionally, gel permeation chromatography (GPC) results showed a significant increase in molecular weight (۴۲ × ۱۰۴ g/mol) and polydispersity index (۲۲.۱). The modifications improved comonomer incorporation and enhanced key polymer properties, such as molecular weight distribution and bulk density, while maintaining comparable morphology to the unmodified system. These findings highlight the potential of tailored catalyst modifications for advancing polyolefin production.

کلیدواژه ها:

Support ، Ziegler-Natta ، Ethylene Polymerization ، morphology ، Precipitation ، Surfactant