Olefin polymerization and copolymerization
Nona Ghasemi Hamedani; Fatemeh Poorsank; Hassan Arabi; Seyed Mehdi Ghafelehbashi
Abstract
Insights have been developed into the influence of different structures, including bismethoxymethylfluorene (B) and 2,2-diisopropyl succinate (I), on both internal donor (ID) and external donor (ED) roles on the performance of MgCl2/ID/TiCl4. Catalyst performance including activity, hydrogen response, ...
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Insights have been developed into the influence of different structures, including bismethoxymethylfluorene (B) and 2,2-diisopropyl succinate (I), on both internal donor (ID) and external donor (ED) roles on the performance of MgCl2/ID/TiCl4. Catalyst performance including activity, hydrogen response, molecular weight distribution and thermal properties is explained through the coordination nature of external donors and its correlation with the internal donor. Replacement of the typical alkoxysilane ED with B and I leads to an overall decrease in activity, which is more pronounced (average 1.4 times) in systems with similar structures as ID and ED. However, these compounds significantly enhance hydrogen response. The use of B as ED leads to an average 1.5-fold increase in MFI and usage of I as ED results in an average 1.1 times increase in MFI. Changing the ED influenced the thermal properties so that in the catalyst with the succinate structure as ID, altering the ED from alkoxysilane to I, leads to an increase in crystallinity from 43.86% to 48.12%. These findings suggest that the choice of package of internal and external donor can significantly influence the resulting polymer characteristics.
Olefin polymerization and copolymerization
Hiren Bhajiwala; Virendrakumar Gupta
Abstract
Ultra-high molecular weight polyethylene (UHMWPE) was synthesized using Bi-supported SiO2/MgCl2/TiCl4 (Si-Mg-Ti) Ziegler-Natta catalyst in conjugation with triethyl aluminum (TEA). The impact of temperature and the presence of a chain-terminating agent were examined in the context of ethylene polymerization. ...
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Ultra-high molecular weight polyethylene (UHMWPE) was synthesized using Bi-supported SiO2/MgCl2/TiCl4 (Si-Mg-Ti) Ziegler-Natta catalyst in conjugation with triethyl aluminum (TEA). The impact of temperature and the presence of a chain-terminating agent were examined in the context of ethylene polymerization. The findings showed that as temperature decreases, the activity of the polymerization decreases, and the molecular weight of the polymer increases. Conversely, in the presence of a chain-terminating agent, the molecular weight of the polymer decreases. The introduction of Triethyl borate (TEB) and Tetraethoxy silane (TEOS) as an external donor has a pronounced effect on the catalyst activity, causing a significant decrease, while simultaneously leading to a substantial increase in the viscosity average molecular weight (Mv). Additionally, when a chain-terminating agent is added along with Triethyl borate (TEB) in the system, it results in a significant decrease in molecular weight, albeit with a slight increase in activity compared to a system without a donor. The crystallinity, particle size and bulk density of the polymer synthesized with and without external donor also investigated.
