The invention provides a process for the preparation of a multimodal high density polyethylene (HDPE) having a melt flow rate (MFR.sub.2) of 0.1 to 4.0 g/10 min, said process comprising: (i) polymerising ethylene in a first polymerisation stage in the presence of a Ziegler-Natta catalyst to prepare a first ethylene homopolymer having a MFR.sub.2 from 10 to 500 g/10 min; (ii) polymerising ethylene in a second polymerisation stage in the presence of said catalyst and said first ethylene homopolymer to prepare an ethylene homopolymer mixture comprising said first ethylene homopolymer and a second ethylene homopolymer, said mixture having a MFR.sub.2 from 50 to 1000 g/10 min; and (iii) polymerising ethylene and at least one alpha-olefin comonomer in a third polymerisation stage in the presence of said catalyst and said ethylene homopolymer mixture to prepare said multimodal HDPE.

An antistatic composition and an olefin polymerization method are provided. The antistatic composition includes: an oil-soluble hyperbranched polyamidoamine, an oil-soluble surfactant and an aliphatic hydrocarbon, wherein the oil-soluble hyperbranched polyamidoamine has a molecular weight with a range of 5000 to 40000. The olefin polymerization method includes: adding an olefin, a catalyst and the antistatic composition into a polymerization reactor to undergo a polymerization to obtain a polyolefin.

An antistatic composition and an olefin polymerization method are provided. The antistatic composition includes: an oil-soluble hyperbranched polyamidoamine, an oil-soluble surfactant and an aliphatic hydrocarbon, wherein the oil-soluble hyperbranched polyamidoamine has a molecular weight with a range of 5000 to 40000. The olefin polymerization method includes: adding an olefin, a catalyst and the antistatic composition into a polymerization reactor to undergo a polymerization to obtain a polyolefin.

An object of the present disclosure is to provide a terminal-modified conjugated diene polymer capable of improving fracture resistance of a rubber article. Specifically, a terminal-modified conjugated diene polymer is characterized in that a content of catalyst residue therein derived from a catalyst used in polymerization is less than 60 ppm.

Techniques are provided for catalyst preparation. A system for catalyst preparation may include an agitator disposed inside a polymerization catalyst tank and configured to mix a polymerization catalyst and a solvent to generate a polymerization catalyst solution. The system may also include a heating system coupled to the polymerization catalyst tank and configured to maintain a temperature of the polymerization catalyst solution above a threshold. The system may also include a precontactor configured to receive feed streams comprising an activator and the polymerization catalyst solution from the polymerization catalyst tank to generate a catalyst complex. The system may also include a transfer line configured to transfer the catalyst complex from an outlet of the precontactor to a reactor.

Techniques are provided for catalyst preparation. A system for catalyst preparation may include an agitator disposed inside a polymerization catalyst tank and configured to mix a polymerization catalyst and a solvent to generate a polymerization catalyst solution. The system may also include a heating system coupled to the polymerization catalyst tank and configured to maintain a temperature of the polymerization catalyst solution above a threshold. The system may also include a precontactor configured to receive feed streams comprising an activator and the polymerization catalyst solution from the polymerization catalyst tank to generate a catalyst complex. The system may also include a transfer line configured to transfer the catalyst complex from an outlet of the precontactor to a reactor.

This invention relates homogeneous (solution) polymerization of propylene at higher temperatures (80 C. or more) using bisindenyl metallocene catalyst compounds having long (at least 4 carbon atoms) linear alkyl groups substituted at the 2-position and substituted or unsubstituted aryl groups at the 4-position.

This invention relates homogeneous (solution) polymerization of propylene at higher temperatures (80 C. or more) using bisindenyl metallocene catalyst compounds having long (at least 4 carbon atoms) linear alkyl groups substituted at the 2-position and substituted or unsubstituted aryl groups at the 4-position.

The invention relates to a process for preparing aminomethylated bead polymers using condensed formaldehydes and carbonyl halides.

Provided are a method for producing a multibranched polymer that can produce a multibranched polymer having a narrow molecular weight distribution in a one-pot procedure and the multibranched polymer. A method for producing a multibranched polymer includes the step of polymerizing a first vinyl monomer having a polymerization-initiating group in an -position of a vinyl bond and a second vinyl monomer free of polymerization-initiating group in an -position of a vinyl bond by a living radical polymerization.