Efficient synthesis of thermoplastic elastomeric amorphous ultra-high molecular weight atactic polypropylene (UHMWaPP)

The synthesis of amorphous ultra-high molecular weight atactic polypropylene (UHMWaPP), with molecular weights (Mw) up to 2.0 MDa and narrow polydispersities is reported using remarkably efficient permethylindenyl-phenoxy (PHENI*) titanium complexes.

Synthesis of zirconocene complexes and their use in slurry-phase polymerisation of ethylene

A new family of zirconocene complexes of the type (^3-RInd^#)₂ZrX₂ (where Ind^# = C₆Me₅H and R = Me, Et and Ph) have been synthesised and fully characterised. Six new crystal structures have been reported (meso-(^3-EtInd^#)₂ZrBr₂, rac-(^3-EtInd^#)₂ZrCl₂, rac-(^3-EtInd^#)₂Zr(CH₂Ph)₂, meso-(^3-EtInd^#)₂Zr(CH₂Ph)₂, meso-(^3-MeInd^#)₂ZrBr₂ and meso-(^3-MeInd^#)₂Zr(CH₂Ph)₂). The complexes were studied for slurry-phase ethylene polymerisation when immobilised on solid polymethylaluminoxane (sMAO). Variation in the initiation group was found to have greater influence over polymerisation activity for meso-catalysts than rac-catalysts, with meso-alkyl catalysts showing higher polymerisation activities than meso-halide. Below 70 °C, polymerisation activity follows the order sMAO-meso-(^3-EtInd^#)₂Zr(CH₂Ph)_2, sMAO-meso-(^3-EtInd^#)₂ZrCl₂ and sMAO-meso-(^3-EtInd^#)₂ZrBr₂ (activities of 657, 561, and 452 kg_PE mol_M⁻¹ h⁻¹ bar⁻¹, respectively). sMAO-meso-(^3-EtInd^#)₂ZrBr₂ produces HDPE with the highest molecular weight, followed by sMAO-meso-(^3-EtInd^#)₂ZrCl₂ and sMAO-meso-(^3-EtInd^#)₂Zr(CH₂Ph)₂ (M_w of 503, 406, and 345 kg mol⁻¹, respectively, at 50 °C). sMAO-meso-(^3-MeInd^#)₂ZrBr₂ produced HDPE with almost identical molecular weights to sMAO-meso-(^3-EtInd^#)₂ZrCl₂ (395 kg mol⁻¹ at 50 °C).

A new family of zirconocene complexes of the type (^3-RInd^#)₂ZrX₂ (where Ind^# = C₆Me₅H and R = Me, Et and Ph) have been synthesised and fully characterised.

Group 4 permethylindenyl complexes for slurry-phase polymerisation of ethylene

Supported group 4 permethylindenyl based catalysts displayed extremely high ethylene polymerisation activity affording popcorn shaped low molecular weights polyethylenes.

A Comparative Study of AlCl3and FeCl2-Modified TiCl4/MgCl2/THF Catalytic System in the Presence of Hydrogen for Ethylene Polymerization

Ethylene homopolymerization over TiCl4/MgCl2/THF catalysts modified with different metal halide additives (AlCl3and FeCl2) with and without hydrogen was investigated based on catalytic activity and polymer properties. Lewis acid modification can improve activity because it can remove the remaining THF in the final catalyst, which can poison the catalyst active sites via the ring-opening of THF that was confirmed by XRD measurements. Moreover, the activity enhancement was due to the formation of acidic sites by modifying the catalysts with Lewis acids. Thus, FeCl2doped catalyst (Fe-THF) exhibited the highest activity followed by AlCl3doped catalyst (Al-THF) and undoped catalyst (None-THF). In H2/C2H4molar ratio of 0.08, Fe-THF showed a better hydrogen response than Al-THF due to more titanium cluster distribution. Fe-THF is considered to have more clustered Ti species than Al-THF. As a consequence, it led us to obtain more possible chances to precede chain transfer reaction by hydrogen. The molecular weight, melting temperature, and crystallinity of obtained polymers were investigated by GPC and DSC measurement, respectively.

Effect of Polymerization Conditions on Thermal and Mechanical Properties of Ethylene/1-Butene Copolymer Made with Ziegler-Natta Catalysts

The effect of polymerization conditions on thermal and mechanical properties of ethylene/1-butene copolymers synthesized through titanium-magnesium-supported Ziegler-Natta catalysts was studied. The increase in hydrogen pressure leads to a decrease in molecular weight (MW), storage modulus, and melting temperature. However, it yields an increase in molecular weight distribution (MWD),tan⁡δ, % crystallinity, tensile modulus, yield stress, and strain at break. The effects of ethylene pressure and polymerization temperature on the copolymer MW, MWD and thermal and mechanical properties have been investigated. However, the impacts of ethylene pressure and polymerization temperature on copolymer modulus, tensile strength, % crystallinity, crystallization peak temperature, yield stress, strain at break, and yield strain are marginal. The hydrogen pressure plays a major role in controlling the copolymer properties because it acts as an efficient chain transfer agent during polymerization reaction. The MW is the key parameter that influences flow activation energy. However, the other mechanical, dynamic mechanical, and thermal properties not only depend on MW but are also influenced by other parameters.