Provided is a polyethylene powder having a density of 910 kg/m.sup.3 or more and less than 935 kg/m.sup.3 and an average particle diameter of 50 μm or more and less than 140 μm, wherein the polyethylene powder contains a particle having a particle diameter of 60 μm and a particle having a particle diameter of 100 μm, the compressive strength at 10% displacement of the particle having a particle diameter of 60 μm is 2.0 MPa or more and less than 5.0 MPa, and the compressive strength at 10% displacement of the particle having a particle diameter of 60 μm is 0.5 times or more and less than 1.3 times the compressive strength at 10% displacement of the particle having a particle diameter of 100 μm.

Provided is a polyethylene powder having a density of 910 kg/m.sup.3 or more and less than 935 kg/m.sup.3 and an average particle diameter of 50 μm or more and less than 140 μm, wherein the polyethylene powder contains a particle having a particle diameter of 60 μm and a particle having a particle diameter of 100 μm, the compressive strength at 10% displacement of the particle having a particle diameter of 60 μm is 2.0 MPa or more and less than 5.0 MPa, and the compressive strength at 10% displacement of the particle having a particle diameter of 60 μm is 0.5 times or more and less than 1.3 times the compressive strength at 10% displacement of the particle having a particle diameter of 100 μm.

A polyethylene powder satisfying (Requirements 1 to 3):

(Requirement 1): viscosity-average molecular weight (Mv) is 200,000 or more and 3,000,000 or less
(Requirement 2): complex viscosity |η*|.sub.m obtained by measurement under predetermined <Conditions for Measurement of Slurry Viscoelasticity>satisfies the following formula (1):
590.0×(Mv×10.sup.−4).sup.1.18≥|η*|.sub.m≥13.3×(Mv×10.sup.−4).sup.1.18 (1)
(Requirement 3): a value of any peak when d(log|η*|)/dT is plotted against temperature is 1.0 or more and 3.0 or less.

A polyethylene powder satisfying (Requirements 1 to 3):

(Requirement 1): viscosity-average molecular weight (Mv) is 200,000 or more and 3,000,000 or less
(Requirement 2): complex viscosity |η*|.sub.m obtained by measurement under predetermined <Conditions for Measurement of Slurry Viscoelasticity>satisfies the following formula (1):
590.0×(Mv×10.sup.−4).sup.1.18≥|η*|.sub.m≥13.3×(Mv×10.sup.−4).sup.1.18 (1)
(Requirement 3): a value of any peak when d(log|η*|)/dT is plotted against temperature is 1.0 or more and 3.0 or less.

The present invention relates to a solid Ziegler-Natta catalyst component for olefin polymerization containing an organosilicon element in combination with one or more internal electron donors. The catalyst components, according to the present invention, are able to produce polypropylene polymers with higher stereo-regularity. The present invention also provides a phthalate-free catalyst system capable of producing polypropylene with an isotacticity that is equal to or higher than catalyst systems containing phthalate derivatives.

The present invention relates to an ultra-high molecular weight polyethylene (UHMWPE) powder having a BET specific surface area of ≥0.50 m.sup.2/g as determined in accordance with ISO 9277 (2010). Such UHMWPE powder allows for preparation of a gel solution comprising the powder to a desired swelling ratio at moderate temperatures within a reduced swelling period.

The present invention relates to an ultra-high molecular weight polyethylene (UHMWPE) powder having a BET specific surface area of ≥0.50 m.sup.2/g as determined in accordance with ISO 9277 (2010). Such UHMWPE powder allows for preparation of a gel solution comprising the powder to a desired swelling ratio at moderate temperatures within a reduced swelling period.

A process of preparing a solid catalyst component for the production of polypropylene includes a) dissolving a halide-containing magnesium compound in a mixture, the mixture including an epoxy compound, an organic phosphorus compound, and a hydrocarbon solvent to form a homogenous solution; b) treating the homogenous solution with an organosilicon compound during or after the dissolving step; c) treating the homogenous solution with a first titanium compound in the presence of a first non-phthalate electron donor, and an organosilicon compound, to form a solid precipitate; and d) treating the solid precipitate with a second titanium compound in the presence of a second non-phthalate electron donor to form the solid catalyst component, where the process is free of carboxylic acids and anhydrides.

A process of preparing a solid catalyst component for the production of polypropylene includes a) dissolving a halide-containing magnesium compound in a mixture, the mixture including an epoxy compound, an organic phosphorus compound, and a hydrocarbon solvent to form a homogenous solution; b) treating the homogenous solution with an organosilicon compound during or after the dissolving step; c) treating the homogenous solution with a first titanium compound in the presence of a first non-phthalate electron donor, and an organosilicon compound, to form a solid precipitate; and d) treating the solid precipitate with a second titanium compound in the presence of a second non-phthalate electron donor to form the solid catalyst component, where the process is free of carboxylic acids and anhydrides.

The ultrahigh-molecular-weight polyethylene powder of the present invention is an ultrahigh-molecular-weight polyethylene powder having a viscosity-average molecular weight Mv of 10×10.sup.4 or higher and 1000×10.sup.4 or lower, wherein viscosity-average molecular weight Mv(A) of a kneaded product obtained by kneading under specific kneading conditions, and the Mv satisfy the following relationship: “{Mv−Mv(A)}/Mv is 0.20 or less”, and the ultrahigh-molecular-weight polyethylene powder contains an ultrahigh-molecular-weight polyethylene powder having a particle size of 212 μm or larger, wherein the powder having a particle size of 212 μm or larger has an average pore volume of 0.6 ml/g or larger and an average pore size of 0.3 μm or larger.