Synthesis of vinyl-terminated HDPE and PE/xGnP composite using dinuclear Co-based catalyst

• Published in: Inorganica Chimica Acta 2020-03, Vol.502, p.119354, Article 119354
• Main Authors: Rahimipour, Enayat, Zohuri, Gholamhossein, Kimiaghalam, Mahsa, Khoshsefat, Mostafa
• Format: Article
• Language: English
• Subjects: Catalysts; Ethylene polymerization; Late transition metal catalysts; Methylaluminoxane; Morphology; Multinuclear catalysts; Nano-composites; Polyethylene; Polyethylenes; Scanning electron microscopy; Transition metals
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/j.ica.2019.119354

[Display omitted] •New dinuclear Co-based catalyst affording vinyl-terminated PE was prepared.•Greater activity along with higher thermal stability of dinuclear structure was obtained in comparison to mononuclear.•Layered morphology for the catalyst dedicated to the final PE shape through replication phenomenon.•Presence of xGnP affected catalyst behavior and polymer properties. To continue our previous researches on dinuclear late transition metal catalysts, a dinuclear catalyst based on cobalt (C) was prepared and used for polymerization of ethylene in the presence of modified methylaluminoxane (MMAO) as cocatalyst. The behavior of catalyst C was compared with its mononuclear analogue (M). The initial results showed higher in both activity and stability of the catalyst C in comparison to catalyst M. Based on this, the studies were focused on the catalyst C. The maximum activity of C observed at [Al]/[Co] molar ratio of 2000:1, reaction temperature of 60 °C that was equal to 6.8 × 106 g PE/mol Co.h. The GPC-IR results showed that the synthesized polyethylene has low Mw (Mw = 7.0 × 103 g/mol) along with a narrow MWD (2.56). Moreover, the polyethylene was containing low SCB (7.8 CH3/1000C) in confirmation of high crystallinity obtained by DSC (χc = 60%). Due to layered morphology of the catalyst C observed through SEM images, the shape of PE was layered consistent on replication phenomenon. Besides, this morphology observed in SEM and TEM images of PE/xGnP composites with higher intensity. The presence of xGnP also led to a slightly greater activity of the catalyst C along with higher vinyl content and lower starting degradation temperature of the obtained PE.