Polymerization of propylene using the high‐activity Ziegler–Natta catalyst system SiO₂/MgCl₂ (ethoxide type)/TiCl₄/Di‐n‐butyl phthalate/triethylaluminum/dimethoxy methyl cyclohexyl silane

Abstract

ABSTRACT:The bisupported Ziegler-Natta catalyst system SiO 2 /MgCl 2 (ethoxide type)/TiCl 4 /di-n-butyl phthalate/triethylaluminum (TEA)/dimethoxy methyl cyclohexyl silane (DMMCHS) was prepared. TEA and di-n-butyl phthalate were used as a cocatalyst and an internal donor, respectively. DMMCHS was used as an external donor. The slurry polymerization of propylene was studied with the catalyst system in n-heptane from 45 to 70°C. The effects of the TEA and H 2 concentrations, temperature, and monomer pressure on the polymerization were investigated. The optimum productivity was obtained at [Al]/[DMMCHS]/[Ti] ϭ 61.7:6.2:1 (mol/mol/mol). The highest activity of the catalyst was obtained at 60°C. Increasing the H 2 concentration to 100 mL/L increased the productivity of the catalyst, but a further increase in H 2 reduced the activity of the catalyst.Increasing the propylene pressure from 1 to 7 bar significantly increased the polymer yield. The isotacticity index (II) decreased with increasing TEA, but the H 2 concentration, temperature, and monomer pressure did not have a significant effect on the II value. The viscosity-average molecular weight decreased with increasing temperature and with the addition of H 2 . Three catalysts with different Mg/Si molar ratios were studied under the optimum conditions. The catalyst with a Mg/Si molar ratio of approximately 0.93 showed the highest activity.

Synthesis of polypropylene/clay nanocomposites using bisupported Ziegler‐Natta catalyst

“…As shown in this table, the MFI of the samples was considerably affected by H 2 presence during polymerization. It could be attributed to increasing in chain‐transfer reactions which results in decreasing in MW 16. Figure 2 also shows the effect of the H 2 on the molecular weight of the samples.…”

SiO2‐covered graphene oxide nanohybrids for in situ preparation of UHMWPE/GO(SiO2) nanocomposites with superior mechanical and tribological properties

“…51 SiO 2 nanoparticles can also affect the overall activity and performance of Ziegler-Natta catalysts. [52][53][54][55] According to the literature, 56 SiO 2 nanoparticles can be utilized as an effectively appropriate support with easily tunable particle size and morphology for the industrial production of polyolefin. Chemical grafting of SiO 2 nanoparticles on the surface of GO nanosheets and utilization of the hybridized nanostructure in the Ziegler-Natta catalyst preparation result in the higher exfoliation of GO nanosheets, catalyst activity promotion, and improve the dispersion and distribution of the hybridized nanostructures in the polymer matrix.…”

Copolymerization of ethylene–propylene using high‐activity bi‐supported Ziegler–Natta TiCl4 catalyst

“…19 At temperatures Ͼ70°C, a similar behavior was reported for the Ziegler-Natta catalyst. 11,20 The M v decreases from 106,000 to 39,200 by increasing the temperature from 40 to 60°C. As shown in Figure 8, a linear decrease in the M v with increasing temperature was observed.…”