Effect of catalyst isospecificity on olefin copolymerization

Abstract

Copolymerizations of ethylene with propene, ethylene with 1-hexene, and propene with 1-hexene were performed at 40°C under atmospheric pressure by using the aspecific catalyst composed of TiCI,/MgCl, and A(c2HS)s and the isospecific Solvay-type catalyst composed of TiCI, and Cp,Ti(CH,),. In case of ethylene-propene copolymerization, the catalyst isospecificity affects neither the monomer reactivity ratios nor the monomer distribution in poly(ethy1eneco-propene). The thermal properties of poly(ethy1ene-co-propene) are, however, not the same for the two catalysts due to the different tacticity of long propylene sequences contained in the copolymers. In the copolymerizations of ethylene and 1-hexene and of propene and 1-hexene, the monomer reactivity ratios differ to some extent between the two catalyst systems. The aspecific catalyst facilitates incorporation of 1-hexene both in poly(ethylene-co-1-hexene) and poly@ropene-co-I-hexene). The monomer distributions are also different in these copolymers. The aspecific and isospecific catalysts show a tendency to give random and blocky copolymers, respectively.

Ethylene/1-Hexene Copolymerization over Different Phases Titania-Supported Zirconocene Catalysts

“…The obtained polymers were further characterized by 13 C NMR spectroscopy. The triad distributions of the comonomer were calculated according to literature [22]. The results are presented in Table 5, which shows that the distributions in copolymer are almost the same.…”

“…Chemical shifts were referenced internally to the CDCl3 and calculated according to the literature [22]. Sample solution was prepared by dissolving 50 mg of copolymer in 1,2,4-trichlorobenzene and CDCl3.…”

The heterogeneous modified-polypropene-supported Ziegler catalyst/MMAO system for producing ultrahigh molecular weight polyethene and poly(ethene-co-hex-1-ene) with a homogeneous comonomer distribution

“…The composition and triad distribution of the copolymers were estimated by 13 C NMR spectroscopy according to standard techniques 14,18) . 13 C NMR spectra were recorded on a Varian Gemini-300 spectrometer operating at 75.2 MHz at 120 6 solution was added for an internal lock, and hexamethyldisiloxane was used as the internal chemical shift reference.…”

Synthesis of Isotactic Poly(propylene) by Titanium Based Catalysts Containing Diamide Ligands

“…The concentration of propylene in the feed was estimated according to literature. [14] The other reaction conditions and procedures are the same as those for the polymerization in the stainless steel autoclave.…”