Tatsuya Miyatake

36. Polymerization of Styrene and Copolymerization of Styrene with Olefin in the Presence of Soluble Ziegler-Natta Catalysts

Titanium complex catalysts including 2,2′-thiobis(4-methyl-6-tbutylphenoxy) (TBP) group as ligand are highly active toward styrene when combined with methylalumoxane (MAO) as cocatalyst, yielding completely syndiotactic polystyrene with up to 37 kg polymer per g titanium and hour. Copolymerizations of styrene and ethylene have been carried out with these catalysts. The 13 C NMR analysis of the copolymer obtained indicates that the copolymer is an alternating copolymer having isotactic styrene units. The isotactic alternating copolymer is a crystalline polymer with a melting point of 166°C.

13. Microtacticity Distribution of Polypropylenes Prepared with MgCl2 Supported Ti Catalyst Systems

The effect of phenyltrimethoxysilane as an external donor on the microtacticity distribution of the isotactic parts of polypropylenes prepared with MgCl 2 -supported Ti catalyst-AlEt 3 system was studied by programmed temperature column fractionation (PTCF) technique. Both catalysts produce two kinds of isotactic polymers, i.e., low isotactic and highly isotactic. The proportion of highly isotactic polymer increases and the microtacticities of low and highly isotactic polymers increase by the addition of the electron donor. Models for active sites on the Mg-Ti catalyst system and the action of PTMS to each active site are discussed based on these results.

A theoretical study of the ligand effect of thiobisphenoxytitanium complex catalyst on the catalytic activity for ethylene polymerization

Abstract The effect of ortho-substituents (R=methyl, tert -butyl and triisopropylsilyl) of phenoxy groups in thiobisphenoxytitanium complex catalyst on the catalytic activity of ethylene polymerization was analyzed by applying ab initio molecular orbital theory and density functional theory. The calculation results revealed that the activation energy values of ethylene insertion reaction into a methyltitanium bond of thiobisphenoxytitanium complexes with substituents on the ortho position of phenoxy ligands at the RHF level are in good correspondence with the tendency of ethylene polymerization activities. The activation energy values at the B3LYP/DZ, RHF/LANLL2DZ and B3LYP/LANL2DZ//RHF/DZ levels also show similar tendency. While the differences of the molecular weight of polyethylene prepared with these bisphenoxy complexes could not be explained from the activation energy values of β-H elimination reaction and the chain transfer reaction to monomer. The activation energy of ethylene insertion reaction is supposed to control the molecular weight of polyethylene.

Vibrational spectrum of α- and δ-TiCl3

Abstract The vibrational spectrum of α-TiCl 3 is assigned on the basis of a normal coordinate analysis. The i.r. bands shift to higher frequency from α- to δ-TiCl 3 . This is discussed in terms of a dispersion relation for k c in α-TiCl 3 and force constants, where the former is carried out for examining effect on disorder to the c axis in δ-TiCl 3 . The shift is explained in terms of a change in force constants rather than disorder.

The vibrational spectrum and the normal coordinate analysis of β-TiCl3

Abstract The vibrational spectrum of β-TiCl 3 is reported. The observed bands are assigned on the basis of the normal coordinate analysis by use of a valence force field. It was found that the A 2 u mode is lower in frequency than that in α-TiCl 3 and one of the TiTi stretchings is 281 cm −1 , resulting in a TiTi stretching force constant of 81.6 N/m.