Effect of Hydrogen and External Donor on Propylene Polymerization Kinetics with a 4^th‐Generation Ziegler‐Natta Catalyst

Abstract

Apparent kinetic rate constants and activation energies for catalyst activation, deactivation, and propylene propagation with a 4th‐generation Ziegler‐Natta catalyst are estimated. The rate of polymerization in the presence of donor and hydrogen is higher than in their absence. Catalyst activation and propagation rate constants increase with the addition of hydrogen, likely because hydrogen frees 2–1‐terminated dormant sites. The deactivation term was the highest without electron donor, presumably because the nonspecific sites deactivate faster than the specific sites. Apparent activation energies for catalyst activation, deactivation, and propagation are not significantly influenced by the presence of hydrogen or external donor, indicating that they do not affect these mechanisms substantially.

Using Pyrene Excimer Fluorescence To Probe the Interactions between Viscosity Index Improvers and Waxes Present in Automotive Oil

“…25 To acquire the 13 C NMR spectra of the EP copolymers at 120 o C, a Bruker 500 MHz high resolution NMR spectrometer was employed. 26 EP copolymers (0.14 g) were dissolved in TCE-d2. Before acquiring each NMR spectrum, the solution in the NMR tube was homogenized by placing it in a heating block at 120 o C for a minimum of 4 hrs.…”

The Influence of Ziegler-Natta and Metallocene Catalysts on Polyolefin Structure, Properties, and Processing Ability

“…Since the discovery of TiCl 4 /Di/MgCl 2 –AlR 3 /De type propylene polymerization catalysts in the early 1980s, great efforts have been paid to disclosing and understanding the mechanism of electron donor effects, with an aim of further improving the chain structure of PP by applying new Di/De combinations [ 125 , 126 , 127 , 128 , 129 , 130 , 131 , 132 , 133 , 134 , 135 , 136 ]. The main role of Di has been proposed to control the amount and spatial distribution of TiCl 4 adsorbed on the MgCl 2 crystallite surface [ 123 ].…”

Quantifying the Level of Intermacromolecular Interactions in Ethylene–Propylene Copolymers by Using Pyrene Excimer Formation

“…27 The GPC instrument was equipped with the three following detectors placed in series, namely a differential refractive index, 15 o angle light scattering, and differential viscosity detectors. The GPC instrument was also calibrated with polystyrene standards having a narrow molecular weight distribution.…”