Ethylene–hexene copolymerization by heterogeneous and homogeneous Ziegler–Natta catalysts and the “comonomer” effect

Abstract

Homopolymerization of ethylene and 1‐hexene and their copolymerizations were compared to investigate the influence of α‐olefin on the enhancement of ethylene polymerization rate (Rp), which is often referred to as the “comonomer” effect. With the two homogeneous Ziegler–Natta catalysts, Et[Ind]2ZrCl2/MAO and (π‐C5H5)2ZrCl2/MAO (MAO = methylaluminoxane), hexene causes reduction of Rp—in other words a negative “comonomer” effect. In the case of the high activity MgCl2 supported TiCl3 catalysts there is a slight positive “comonomer” effect; the Rp increases by 25 to 70% with the addition of 15 mol % of hexene. The “comonomer” effects in there catalyst systems are much smaller than that observed for the classical TiCl3 catalyst. © 1993 John Wiley & Sons, Inc.

A Comparative Study on the Homo-, Co- and Ter-Polymerization Using Ethylene, 1-Decene and p-Methylstyrene

“…We confirmed the synthesis of PED and PEDM using 1 H NMR, 13 C NMR and FT-IR analysis. T g of PEDM was higher than that of PED, which is possibly due to the rigid molecular feature of the p-MS in the terpolymer.…”

“…These observations were ascribed to the "negative comonomer (p-MS) effect." This negative comonomer effect could be explained by the fact that p-MS that was inserted into the copolymer or terpolymer disturbed additional incorporation of other monomers [12,13]. …”

“…We can confirm the insertion of the 1-decene and p-MS into the terpolymer by the characteristic peaks for the CH 3 of the p-MS and the CH of the 1-decene. Figure 4 shows the 13 C NMR spectra of the PE, PED and PEDM. In the case of PEDM in particular, ortho and meta carbon atoms are present in the benzene ring.…”

“…13 C NMR spectra were obtained at 60 °C. The equipment that was used was AVANCE 500 MHz ( Bruker, Karlsruhe, Germany).…”

Synthesis and olefin homo- and copolymerization behavior of new vanadium complexes bearing [OSSO]-type ligands

“…The catalytic activity of all the systems was lower for copolymerization than that for homopolymerization of ethylene. This negative ''comonomer effect'' is frequently observed in ethylene/1-olefin copolymerization with different catalytic systems [39]. The incorporation of 1-olefin into the copolymer at the same 1-olefin concentration depends on the catalytic system type: 1V/Et 2 AlCl was found to give the product with about twice higher content of comonomer than 2V/Et 2 AlCl (Table 1, run 7 vs. 14).…”