A polyethylene powder, wherein, when a free induction decay curve obtained by the Carr-Purcell-Meiboom-Gill method in pulsed NMR is subjected to three-component approximation, the relaxation time T of each component and the abundance R of each component satisfy the following <requirement (1)> and <requirement (2)>:

<Requirement (1)>

An entanglement index at 180 C. determined by (formula I) is 12 to 25 ms:

(entanglement index)=T.sub.R.sub./(R.sub.+R.sub.)+T.sub.R.sub./(R.sub.+R.sub.) (formula I) T.sub.: relaxation time (ms) of low-mobility component R.sub.: abundance (%) of low-mobility component T.sub.: relaxation time (ms) of intermediate component R.sub.: abundance (%) of intermediate component
<Requirement (2)>

An intermediate component ratio at 180 C. determined by (formula II) is 0.25 to 0.5:

(intermediate component ratio)=R.sub./(R.sub.+R)(formula II).

A polyethylene powder, wherein, when a free induction decay curve obtained by the Carr-Purcell-Meiboom-Gill method in pulsed NMR is subjected to three-component approximation, the relaxation time T of each component and the abundance R of each component satisfy the following <requirement (1)> and <requirement (2)>:

<Requirement (1)>

An entanglement index at 180 C. determined by (formula I) is 12 to 25 ms:

(entanglement index)=T.sub.R.sub./(R.sub.+R.sub.)+T.sub.R.sub./(R.sub.+R.sub.) (formula I) T.sub.: relaxation time (ms) of low-mobility component R.sub.: abundance (%) of low-mobility component T.sub.: relaxation time (ms) of intermediate component R.sub.: abundance (%) of intermediate component
<Requirement (2)>

An intermediate component ratio at 180 C. determined by (formula II) is 0.25 to 0.5:

(intermediate component ratio)=R.sub./(R.sub.+R)(formula II).

The present invention presents an ethylene polymer, wherein the ethylene polymer has a weight average molecular weight (Mw) of 200,000 or more and 3,000,000 or less, a proportion of a component (130) with the lowest mobility of 40% or more and 60% or less, and a ratio / of a middle motion component () to a component () with the highest mobility of 1.0 or more and 4.0 or less when a three-component approximation of free induction decay at 130 C. measured by a solid echo method of pulse NMR is performed.

The present invention presents an ethylene polymer, wherein the ethylene polymer has a weight average molecular weight (Mw) of 200,000 or more and 3,000,000 or less, a proportion of a component (130) with the lowest mobility of 40% or more and 60% or less, and a ratio / of a middle motion component () to a component () with the highest mobility of 1.0 or more and 4.0 or less when a three-component approximation of free induction decay at 130 C. measured by a solid echo method of pulse NMR is performed.

A polyethylene powder having an average particle size of 70 m or more and less than 150 m, wherein a compressive strength at a time of 10% displacement of particles having a particle size of 60 m is 1.2 times or more and less than 2.5 times based on a compressive strength at a time of 10% displacement of particles having a particle size of 100 m.

A polyethylene powder having an average particle size of 70 m or more and less than 150 m, wherein a compressive strength at a time of 10% displacement of particles having a particle size of 60 m is 1.2 times or more and less than 2.5 times based on a compressive strength at a time of 10% displacement of particles having a particle size of 100 m.

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 1010.sup.4 or higher and 100010.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: {MvMv(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 m or larger, wherein the powder having a particle size of 212 m or larger has an average pore volume of 0.6 ml/g or larger and an average pore size of 0.3 m or larger.

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 1010.sup.4 or higher and 100010.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: {MvMv(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 m or larger, wherein the powder having a particle size of 212 m or larger has an average pore volume of 0.6 ml/g or larger and an average pore size of 0.3 m or larger.

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.

A polyethylene fiber wherein when a free induction decay (M(t)) of the polyethylene fiber at 90 C. measured by a pulsed nuclear magnetic resonance (NMR) solid echo method is approximated to three components of a component () having a lowest mobility, a component () having an intermediate mobility, and a component () having a highest mobility, by fitting using formula 1 (M(t)= exp(()(t/T.sub.).sup.2)sin bt/bt+ exp((1/Wa)(t/T.sub.).sup.Wa)+ exp(t/T.sub.)), a composition fraction of the component () having the highest mobility is 1% or more and 10% or less, and a relaxation time of the component () having the highest mobility is 100 s or more and 1000 s or less.