Kinetics of ethylene polymerization over titanium-magnesium catalysts: The reasons for the observed second order of polymerization rate with respect to ethylene
Journal Title: Polyolefins Journal - Year 2015, Vol 2, Issue 1
Abstract
The data on the effect of ethylene concentration on polymerization rate for several modifications of modern highly active titanium–magnesium catalysts TiCl4/MgCl2 are presented. These catalysts differ in titanium content and conditions of support preparation, activities, and the shape of kinetic curves. It is found that the observed order of polymerization rate with respect to ethylene in the range of ethylene pressures of 0.5–6 bar is 1.8-2.1 for all catalysts used (polymerization at 80°C, AlEt3 used as a cocatalyst). When AlEt3 was replaced with Al(i-Bu)3, the reaction order decreased to 1.3-1.4. In order to elucidate the possible reasons for the observed high order with respect to ethylene, we analyzed the data on the effect of monomer concentration on the molecular weight of polyethylene. The results gave grounds for suggesting that the observed order with respect to monomer is attributable to the effect of ethylene concentration on the number of active sites. The possible reaction scheme explaining the nonlinear dependence of the polymerization rate on monomer concentration was proposed based on these data.
Authors and Affiliations
Mikhail A. Matsko, Vladimir Aleksandrovich Zakharov, Marina I. Nikolaeva, Tatiana B. Mikenas
Keywords
Related Articles
- EP ID EP283081
- DOI 10.22063/POJ.2015.1112
- Views 110
- Downloads 0
Influence of annealing on anisotropic crystalline structure of HDPE cast films
High density polyethylene (HDPE) films were produced using cast film extrusion process with different draw ratios, ranging from 16.9 to 148.8. Morphology, crystallinty and orientation state of crystalline and amorphous p...
Comparative study of degradation of PP modified with organic pro-degradant subjected to natural and artificial ageing
In abiotic degradation the action of light radiation is one of the most important parameters, because polymers undergo degradation due to the action of light (natural or artificial). The aim of this study was to investig...
The effect of high-energy electron beam on drawn and undrawn high density polyethylene fibers
HDPE monofilaments were obtained using different extruders and drawn by post-extruder equipments. After solidification, drawn and undrawn monofilaments (draw ratio 7:1) were irradiated with 10 MeV electron beams in air a...
Synthesis of cyclic olefin polymers with high glass transition temperature and high transparency using tungsten-based catalyst system
Novel cyclic olefin polymers (COPs) derived from bulky cyclic olefins, tricyclodipentadiene (TCPD) and tricyclo[6.4.0.19,12]-tridec-10-ene (TTE), with high glass transition temperature (Tg), excellent thermal stability,...
In situ stabilization of polypropylene by lignin using a Ziegler-Natta catalyst
A fourth-generation Ziegler-Natta catalyst was prepared to synthesize polypropylene (PP), which was stabilized by in situ polymerization employing lignin as antioxidant. The antioxidant properties of lignin were compared...