Polyolefin composition having improved melt strength

Abstract

The invention is related to a unimodal polyethylene composition, comprising > 97.0 wt.% of an ethylene polymer, wherein the unimodal polyethylene composition has: a density of ≥ 915.0 and ≤ 930.0 kg / m3; a melt flow rate of (MFR2.16) of ≥ 0.17 and ≤ 0.25 g / 10 min, determined in accordance with ASTM D1238 at 190 ºC and measured at 2.16 kg; a weight average molecular weight of (Mw) of ≥ 350 kg / mol and ≤ 450 kg / mol; a zero shear viscosity (η0) of ≥ 550,000.0 Pa.s and ≤ 750,000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 ºC; and a tan delta (0.01 rad / s) of ≥ 1.0 and ≤ 3.5, preferably ≥ 1.0 and ≤ 2.0. The invention further relates to a film comprising the unimodal polyethylene composition and to a process of preparing the unimodal polyethylene composition. In addition, the invention also relates to the use of the unimodal polyethylene composition for film production.

Description

POLYOQ87-WO-ORD1POLYOLEFIN COMPOSITION HAVING IMPROVED MELT STRENGTH FIELD OF INVENTION

[0001] The present invention is directed to a unimodal polyethylene composition and to a film comprising the unimodal polyethylene composition. The invention further relates to the use of the polyethylene composition and to the process of producing the polyethylene composition.BACKGROUND

[0002] Plastic films are used in different sectors, including consumer packaging, industrial packaging and agricultural films. Polymer film manufacturers seek films which have excellent mechanical properties, e.g. high impact strength, tear strength, puncture resistance, toughness and stiffness. The polymers used to make the film must also have good processability, i.e. during the extrusion procedure the bubble formed must be stable and the extruded film should have an even film thickness distribution.

[0003] In many applications, such as blow-molding and blown film applications, melt strength of the polyethylene is a key parameter, frequently measured as elongational viscosity of the polymer. Furthermore, industry practitioners are increasingly demanding films which can be produced from polyethylene composition having ease of processability while the final film product has the desired puncture resistance and tensile properties typically required for packaging application. In particular, it is desired that such compositions impart enhanced bubble stability during blow film production. The stability of the film bubble in a film blowing machine is important for producing high-quality plastic film. If the film bubble is unstable, it can result in various issues such as thickness variations, wrinkles, or other defects.

[0004] In terms of properties, melt strength is a practical measurement that can predict material performance when submitted at elongational deformations. In melt processing technologies, a certain threshold of elongational viscosity is useful for maintaining stability during processes such as coating, blow film production, and fiber spinning. Melt strength influences processing parameters such as bubble stability, which in turn affects thickness variation during blow film production, parison formation during blow molding process, and sagging during profile extrusion.

[0005] In the past, several techniques have been explored to increase melt strength for polyethylene compositions. For example, melt strength can be enhanced by using resins with higher molecular weight. However, such high molecular weight resins may beyond certain limit, affect polymer processability requiring high energy consumption during extrusion.

[0006] Alternatively, the use of highly branched polymers such as low-density polyethylene (LDPE) with enhanced melt strength have also been explored with certain degree of success. However, it has been observed that while some properties are improved, high levels of long-chain branching can compromise other properties. It would be desirable to be able to prepare polyethylene with excellentprocessability and product properties using resins having a suitable balance of molecular weight distribution and long-chain branching distribution.

[0007] Another approach to increase melt strength is to include peroxides to crosslink the polyethylene. However, such an approach is also fraught with some drawbacks. For example, the radicals produced can interact deleteriously with other additives and often rheological properties are unpredictable upon cross-linking. In addition, peroxides add an extra component to the composition, and they require careful handling and storage, which adds to the cost.

[0008] In the past several bimodal or trimodal polyethylene compositions have also been used for improving various rheological and mechanical properties. However, production of bimodal and trimodal polymer compositions often involve the use of series of reactors, which in certain circumstances add to processing complexity and enhanced capital and operating expenses. On the other hand it has been observed that certain unimodal compositions suffer from lower processability and may not be suitable for certain film application.

[0009] Accordingly, one or more objectives of the present invention is to provide a polyethylene composition which has a balance of high melt strength and desired rheological properties for processability, while imparting suitable mechanical properties to a film produced from such a composition, such as tensile and puncture resistance. Yet another objective of the present invention is to provide a polyethylene composition which imparts enhanced bubble stability in blow film production.

[0010] Yet another objective of the present invention is to provide a film having puncture resistance, tensile properties, shrink properties while imparting desired melt strength during film production.DETAILED DESCRIPTION OF THE INVENTION

[0011] The one or more objectives of the invention is achieved by unimodal polyethylene composition, comprising > 97.0 wt.% with regard to the total weight of the polyethylene composition, of an ethylene polymer, wherein the unimodal polyethylene composition has:(a) a density of > 915.0 and < 930.0 kg / m3, preferably > 915.0 and < 925.0 kg / m3, determined in accordance with ASTM DI 505;(b) a melt flow rate of (MFR2ie) of > 0.17 and < 0.25 g / 10 min, preferably > 0.18 and < 0.24 g / 10 min, preferably > 0.19 and < 0.23 g / 10 min, preferably > 0.2 and < 0.23 g / 10 min, determined in accordance with ASTM D1238 at 190 °C and measured at 2.16 kg;(c) a weight average molecular weight of (Mw) of > 350 kg / mol and < 450 kg / mol, preferably > 380 kg / mol and < 430 kg / mol, preferably > 400 kg / mol and < 425 kg / mol, preferably > 410 kg / mol and < 425 kg / mol, determined using Gel Permeation Chromatography(GPC) - Multi-Angle Laser Light Scattering (GPC-MALLS);(d) a zero shear viscosity (r|0) of > 550,000.0 Pa.s and < 750,000.0 Pa.s, preferably > 600,000.0 Pa.s and < 700,000.0 Pa.s, preferably > 620,000.0 Pa.s and < 700,000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and(e) a tan delta (0.01 rad / s) of > 1.0 and < 3.5, preferably > 1.0 and < 2.0, wherein tan delta (0.01 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 0.01 rad / s in accordance with ISO 6721-10 at 190 °C.

[0012] The term “unimodal” as used herein means that the polyethylene composition has a unimodal molecular weight distribution. In other words, the polyethylene composition is not form from a result of a reactor blend of two different ethylene polymers having different molecular weight. Moreover, the polyethylene composition of the present invention is free of blends of two or more ethylene polymers.

[0013] Preferably, the unimodal polyethylene composition, comprises of > 97.0 wt.% and < 100.0 wt.%, preferably > 98.0 and < 100.0 wt.%, preferably > 99.0 and < 100.0 wt.%, with regard to the total weight of the polyethylene composition, of the ethylene polymer. Preferably, the unimodal polyethylene composition, consists of > 97.0 wt.% and < 100.0 wt.%, preferably > 98.0 and < 100.0 wt.%, preferably > 99.0 and < 100.0 wt.%, with regard to the total weight of the polyethylene composition, of the ethylene polymer; and > 0 and < 3.0 wt.%, preferably > 0 and <2.0 wt.%, preferably > 0 and < 1.0 wt.%, with regard to the total weight of the polyethylene composition, of additives. The additives for example may be selected from anti-oxidants, UV stabilizers, color additives and mixtures thereof.

[0014] Preferably, the unimodal polyethylene composition comprises > 98.0 wt.%, preferably > 98.5 wt.% and < 100 wt.%, with regard to the total weight of the polyethylene composition, of an ethylene polymer; and the unimodal polyethylene composition comprises < 2.0 wt.%, preferably > 0 wt.% and < 1.5 wt.%, with regard to the total weight of the polyethylene composition, of additives selected from stabilizers, antioxidant, processing aid and combinations thereof.

[0015] Examples of “unimodal” molecular weight distribution can be seen in U.S. Patent No.8,691,715, Figure 6 of the patent. This is in contrast with a “multimodal” molecular weight distribution, which means that there often (not always) is at least two distinguishable peaks in a molecular weight distribution curve (as determined by GPC).

[0016] Preferably, wherein the unimodal polyethylene composition satisfies the following equation: 3.6xl013x Mw34< r|o< 5.0X1012X MW34, where (r]o) is the zero-shear viscosity (r]o) expressed in the unit of Poise and Mw is the weight average molecular weight, as measured by GPC-MALLS, and expressed in the units of g / mol. The compliance of the polyethylene composition to the above equation isindicative of the balance of processability, melt strength and rheology properties demonstrated by the polyethylene composition of the present invention.

[0017] Preferably the unimodal polyethylene composition has:(a) a density of > 915.0 and < 930.0 kg / m3, preferably > 915.0 and < 925.0 kg / m3, determined in accordance with ASTM DI 505;(b) a melt flow rate of (MFR2 ie) of > 0.17 and < 0.25 g / 10 min, preferably > 0.18 and < 0.24 g / 10 min, preferably > 0.19 and < 0.23 g / 10 min, preferably > 0.2 and < 0.23 g / 10 min, determined in accordance with ASTM D1238 at 190 °C and measured at 2.16 kg;(c) a weight average molecular weight of (Mw) of > 350 kg / mol and < 450 kg / mol, preferably > 380 kg / mol and < 430 kg / mol, preferably > 400 kg / mol and < 425 kg / mol, preferably > 410 kg / mol and < 425 kg / mol, determined using Gel Permeation Chromatography(GPC) - Multi-Angle Laser Light Scattering;(d) a zero shear viscosity (T|O) of > 550,000.0 Pa.s and < 750,000.0 Pa.s, preferably > 600,000.0 Pa.s and < 700,000.0 Pa.s, preferably > 620,000.0 Pa.s and < 700,000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C;(e) a tan delta (0.01 rad / s) of > 1.0 and < 3.5, preferably > 1.0 and < 2.0; wherein tan delta (0.01 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 0.01 rad / s in accordance with ISO 6721-10 at 190 °C; and(f) satisfies the following equation - 3.6xl013x Mw34< r|0< 5.0X1012X MW34, where (r]0) is the zeroshear viscosity (r]0) expressed in the unit of Poise and Mw is the weight average molecular weight, as measured by GPC-MALLS, expressed in the units of g / mol.

[0018] Advantageously, the polyethylene composition of the present invention demonstrates a balance of i) high melt strength during film processing, ii) desired rheological properties including shear thinning that helps in processing while imparting suitable mechanical properties such as puncture resistance, impact resistance and tensile strength to a film produced from such a composition.

[0019] In an aspect of the invention, the invention relates to the use of the unimodal polyethylene composition of the present invention in the production of blow films, wherein the unimodal polyethylene composition imparts improved bubble stability during the blow film production.

[0020] Preferably, wherein the unimodal polyethylene composition has a melt strength of > 6.0 cN and < 10.0 cN, preferably > 6.5 cN and < 8.0 cN, wherein the melt strength is determined at 190 °C with a capillary rheometer equipped with a take-up unit; and / or wherein the unimodal polyethylene composition satisfies the following equation - 3.6xl013x Mw34< r|o< 5.0X1012X MW34, where (r]o) is the zero-shearviscosity (T]0) expressed in the unit of Poise and Mw is the weight average molecular weight, as measured by GPC-MALLS, expressed in the units of g / mol. Preferably, Preferably, wherein the unimodal polyethylene composition has a melt strength of > 6.0 cN and < 10.0 cN, preferably > 6.5 cN and < 8.0 cN, wherein the melt strength is determined at 190 °C with a capillary rheometer equipped with a take-up unit; and wherein the unimodal polyethylene composition satisfies the following equation - 3.6xl013x Mw34< r|o< 5.0xl012x Mw34, where (r]o) is the zero-shear viscosity (r]o) expressed in the unit of Poise and Mw is the weight average molecular weight, as measured by GPC-MALLS, expressed in the units of g / mol.

[0021] Preferably, the unimodal polyethylene composition has:(a) a density of > 915.0 and < 925.0 kg / m3, determined in accordance with ASTM D1505;(b) a melt flow rate of (MFR2 ie) of > 0.19 and < 0.23 g / 10 min, preferably > 0.2 and < 0.23 g / 10 min, determined in accordance with ASTM D1238 at 190 °C and measured at 2.16 kg;(c) a weight average molecular weight of (Mw) of > 400 kg / mol and < 425 kg / mol, preferably > 410 kg / mol and < 425 kg / mol, determined using Gel Permeation Chromatography (GPC) - Multi-Angle Laser Light Scattering;(d) a zero shear viscosity (r]o) of > 550,000.0 Pa.s and < 750,000.0 Pa.s, preferably > 600,000.0 Pa.s and < 700,000.0 Pa.s, preferably > 620,000.0 Pa.s and < 700,000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and(e) a tan delta (0.01 rad / s) of > 1.0 and <3.5, preferably > 1.0 and < 2.0; wherein tan delta (0.01 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 0.01 rad / s in accordance with ISO 6721-10 at 190 °C.

[0022] Preferably, the unimodal polyethylene composition has:(a) a density of > 915.0 and < 925.0 kg / m3, determined in accordance with ASTM D1505;(b) a melt flow rate of (MFR2 ie) of > 0.2 and < 0.23 g / 10 min, determined in accordance with ASTM D1238 at 190 °C and measured at 2.16 kg;(c) a weight average molecular weight of (Mw) of > 410 kg / mol and < 425 kg / mol, determined using Gel Permeation Chromatography (GPC) - Multi-Angle Laser Light Scattering;(d) a zero shear viscosity (r|o) of > 600,000.0 Pa.s and < 700,000.0 Pa.s, preferably > 620,000.0 Pa.s and < 700,000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and(e) atan delta (0.01 rad / s) of > 1.0 and < 2.0; wherein tan delta (0.01 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 0.01 rad / s in accordance with ISO 6721-10 at 190 °C.

[0023] Preferably, the unimodal polyethylene composition has:(a) a density of > 915.0 and < 925.0 kg / m3, determined in accordance with ASTM D1505;(b) a melt flow rate of (MFR2ie) of > 0.2 and < 0.23 g / 10 min, determined in accordance with ASTM D1238 at 190 °C and measured at 2.16 kg;(c) a weight average molecular weight of (Mw) of > 410 kg / mol and < 425 kg / mol, determined using Gel Permeation Chromatography (GPC) - Multi-Angle Laser Light Scattering;(d) a zero shear viscosity (r]o) of > 600,000.0 Pa.s and < 700,000.0 Pa.s, preferably > 620,000.0 Pa.s and < 700,000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C;(e) atan delta (0.01 rad / s) of > 1.0 and < 2.0; wherein tan delta (0.01 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 0.01 rad / s in accordance with ISO 6721-10 at 190 °C; and(f) a zero-shear viscosity (T|O) expressed in the unit of Poise and weight average molecular weight (Mw) of the unimodal polyethylene, as measured by GPC-MALLS, expressed in the units of g / mol, and satisfies the following equation - 3.6xl013x Mw34< r|o< 5.0X1012X MW34.Cross-over Point

[0024] One of the methods to measure the melt strength is the use of the cross-over points. Crossover point is defined as the shear rate at which the loss modulus (G”) equals storage modulus (G’). As may be appreciated by a skilled person, lower the crossover point of the loss modulus (G") and storage modulus (G1) greater is the melt strength.

[0025] Preferably, the unimodal polyethylene composition has a cross-over point ranging from > 0.2 rad / s and < 0.5 rad / s, preferably > 0.25 rad / s and < 0.4 rad / s, wherein cross-over point is defined as the shear rate at which the loss modulus (G”) equals storage modulus (G’).

[0026] Preferably, the unimodal polyethylene composition has:(a) a density of > 915.0 and < 925.0 kg / m3, determined in accordance with ASTM D1505;(b) a melt flow rate of (MFR2ie) of > 0.19 and < 0.23 g / 10 min, preferably > 0.2 and < 0.23 g / 10 min, determined in accordance with ASTM D1238 at 190 °C and measured at 2.16 kg;(c) a weight average molecular weight of (Mw) of > 400 kg / mol and < 425 kg / mol, preferably > 410 kg / mol and < 425 kg / mol, determined using Gel Permeation Chromatography (GPC) - Multi-Angle Laser Light Scattering;(d) a zero shear viscosity (r]0) of > 550,000.0 Pa.s and < 750,000.0 Pa.s, preferably > 600,000.0 Pa.s and < 700,000.0 Pa.s, preferably > 620,000.0 Pa.s and < 700,000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C;(e) a tan delta (0.01 rad / s) of > 1.0 and <3.5, preferably > 1.0 and < 2.0; wherein tan delta (0.01 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 0.01 rad / s in accordance with ISO 6721-10 at 190 °C; and(f) a cross-over point ranging from > 0.2 rad / s and < 0.5 rad / s, preferably > 0.25 rad / s and < 0.4 rad / s, wherein cross-over point is defined as the shear rate at which the loss modulus (G”) equals storage modulus (G’).Tan Delta at various shear rates

[0027] Tan delta is another indicator of the molecular architecture of a polymer sample: molecular weight, molecular weight distribution and LCB and therefore, also of melt strength. Materials that exhibit higher melt strength generally tend to have lower tan delta values, specially at lower frequencies. In an aspect of the invention, the polyethylene composition has sufficiently low tan delta values that aids in processability.

[0028] Preferably, (a) wherein the unimodal polyethylene composition has a tan delta (100 rad / s) of > 0.4 and < 0.65, preferably > 0.4 and < 0.62, wherein tan delta (100 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 100 rad / s in accordance with ISO 6721-10 at 190 °C; and / or (b) wherein the unimodal polyethylene composition has atan delta (10 rad / s) of > 0.65 and < 0.75; wherein tan delta (10 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 10 rad / s in accordance with ISO 6721-10 at 190 °C; and / or (c) wherein the unimodal polyethylene composition has atan delta (1.0 rad / s) of > 0.75 and < 0.9; wherein tan delta (1.0 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 1.0 rad / s in accordance with ISO 6721-10 at 190 °C.

[0029] Preferably, the unimodal polyethylene composition has:(a) a density of > 915.0 and < 925.0 kg / m3, determined in accordance with ASTM D1505;(b) a melt flow rate of (MFR2 ie) of > 0.19 and < 0.23 g / 10 min, preferably > 0.2 and < 0.23 g / 10 min, determined in accordance with ASTM D1238 at 190 °C and measured at 2.16 kg;(c) a weight average molecular weight of (Mw) of > 400 kg / mol and < 425 kg / mol, preferably > 410 kg / mol and < 425 kg / mol, determined using Gel Permeation Chromatography (GPC) - Multi-Angle Laser Light Scattering;(d) a zero shear viscosity (r]o) of > 550,000.0 Pa.s and < 750,000.0 Pa.s, preferably > 600,000.0 Pa.s and < 700,000.0 Pa.s, preferably > 620,000.0 Pa.s and < 700,000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C;(e) a tan delta (0.01 rad / s) of > 1.0 and <3.5, preferably > 1.0 and < 2.0; wherein tan delta (0.01 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 0.01 rad / s in accordance with ISO 6721-10 at 190 °C;(f) a cross-over point ranging from > 0.2 rad / s and < 0.5 rad / s, preferably > 0.25 rad / s and < 0.4 rad / s, wherein cross-over point is defined as the shear rate at which the loss modulus (G”) equals storage modulus (G’);(g) a tan delta (100 rad / s) of > 0.4 and < 0.62, wherein tan delta (100 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 100 rad / s in accordance with ISO 6721-10 at 190 °C;(h) a tan delta (10 rad / s) of > 0.65 and < 0.75; wherein tan delta (10 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 10 rad / s in accordance with ISO 6721-10 at 190 °C; and(i) a tan delta (1.0 rad / s) of > 0.75 and < 0.9; wherein tan delta (1.0 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 1.0 rad / s in accordance with ISO 6721-10 at 190 °C.Melt Flow Rate @ 21, 6kg

[0030] Preferably wherein the unimodal polyethylene composition has a melt flow rate of (MFR21 e) of > 12.0 and < 22.0 g / 10 min, preferably > 15.0 and < 20.0 g / 10 min, determined in accordance with ASTM DI 238 at 190 °C and measured at 21.6 kg.Complex viscosity ((n))

[0031] Preferably, the unimodal polyethylene composition has a complex viscosity (v]ioo) at a shear rate of 100 rad / s of > 780.0 Pa.s and < 910.0 Pa.s, preferably > 800.0 Pa.s and < 900.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and / or (b) wherein the unimodal polyethylene composition has a complex viscosity (T|O .1) at a shear rate of 0.1 rad / s between > 48000.0 Pa.s and < 66000.0 Pa.s, preferably > 50000.0 Pa.s and < 60000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and / or (c) wherein the unimodal polyethylene composition has a complex viscosity (T]I O) at a shear rate of 1.0 rad / sof > 12000.0 Pa.s and < 16000.0 Pa.s, preferably > 14000.0 Pa.s and < 15000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C.

[0032] Preferably, the unimodal polyethylene composition has a complex viscosity (r]ioo) at a shear rate of 100 rad / s of > 780.0 Pa.s and < 910.0 Pa.s, preferably > 800.0 Pa.s and < 900.0 Pa.s, determined in accordance with ISO 6721 - 10 at 190 °C; and wherein the unimodal polyethylene composition has a complex viscosity (r|o i) at a shear rate of 0.1 rad / s between > 48000.0 Pa.s and < 66000.0 Pa.s, preferably > 50000.0 Pa.s and < 60000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and wherein the unimodal polyethylene composition has a complex viscosity (r|i o) at a shear rate of 1.0 rad / s of > 12000.0 Pa.s and < 16000.0 Pa.s, preferably > 14000.0 Pa.s and < 15000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C.

[0033] Preferably, the unimodal polyethylene composition has:(a) a density of > 915.0 and < 925.0 kg / m3, determined in accordance with ASTM D1505;(b) a melt flow rate of (MFR2 ie) of > 0.19 and < 0.23 g / 10 min, preferably > 0.2 and < 0.23 g / 10 min, determined in accordance with ASTM D1238 at 190 °C and measured at 2.16 kg;(c) a weight average molecular weight of (Mw) of > 400 kg / mol and < 425 kg / mol, preferably > 410 kg / mol and < 425 kg / mol, determined using Gel Permeation Chromatography (GPC) - Multi-Angle Laser Light Scattering;(d) a zero shear viscosity (r]o) of > 550,000.0 Pa.s and < 750,000.0 Pa.s, preferably > 600,000.0 Pa.s and < 700,000.0 Pa.s, preferably > 620,000.0 Pa.s and < 700,000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C;(e) a tan delta (0.01 rad / s) of > 1.0 and <3.5, preferably > 1.0 and < 2.0; wherein tan delta (0.01 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 0.01 rad / s in accordance with ISO 6721-10 at 190 °C;(f) a cross-over point ranging from > 0.2 rad / s and < 0.5 rad / s, preferably > 0.25 rad / s and < 0.4 rad / s, wherein cross-over point is defined as the shear rate at which the loss modulus (G”) equals storage modulus (G’);(g) a tan delta (100 rad / s) of > 0.4 and < 0.62, wherein tan delta (100 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 100 rad / s in accordance with ISO 6721-10 at 190 °C;(h) a tan delta (10 rad / s) of > 0.65 and < 0.75; wherein tan delta (10 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 10 rad / s in accordance with ISO 6721-10 at 190 °C;(i) a tan delta (1.0 rad / s) of > 0.75 and < 0.9; wherein tan delta (1.0 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 1.0 rad / s in accordance with ISO 6721-10 at 190 °C;(j) a complex viscosity (T|IOO) at a shear rate of 100 rad / s of > 780.0 Pa.s and < 910.0 Pa.s, preferably > 800.0 Pa.s and < 900.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C;(k) a complex viscosity (r|o i) at a shear rate of 0.1 rad / s between > 48000.0 Pa.s and < 66000.0 Pa.s, preferably > 50000.0 Pa.s and < 60000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and (l) a complex viscosity (ip O) at a shear rate of 1.0 rad / s of > 12000.0 Pa.s and < 16000.0 Pa.s, preferably > 14000.0 Pa.s and < 15000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C.

[0034] Preferably, the unimodal polyethylene composition has a ratio of complex viscosity (r|o ,OI) to complex viscosity (r]ioo) between > 180.0 and < 230.0, preferably > 190.0 and < 220.0, where complex viscosity (r|o ,OI) is the complex viscosity at a shear rate of 0.01 rad / s and complex viscosity (r]ioo) is complex viscosity at a shear rate of 100 rad / s, each of which is determined in accordance with ISO 6721-10 at 190 °C.

[0035] Preferably, the unimodal polyethylene composition has:(a) a density of > 915.0 and < 925.0 kg / m3, determined in accordance with ASTM D1505;(b) a melt flow rate of (MFR2ie) of > 0.19 and < 0.23 g / 10 min, preferably > 0.2 and < 0.23 g / 10 min, determined in accordance with ASTM D1238 at 190 °C and measured at 2.16 kg;(c) a weight average molecular weight of (Mw) of > 400 kg / mol and < 425 kg / mol, preferably > 410 kg / mol and < 425 kg / mol, determined using Gel Permeation Chromatography (GPC) - Multi-Angle Laser Light Scattering;(d) a zero shear viscosity (r]o) of > 550,000.0 Pa.s and < 750,000.0 Pa.s, preferably > 600,000.0 Pa.s and < 700,000.0 Pa.s, preferably > 620,000.0 Pa.s and < 700,000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C;(e) a tan delta (0.01 rad / s) of > 1.0 and <3.5, preferably > 1.0 and < 2.0; wherein tan delta (0.01 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 0.01 rad / s in accordance with ISO 6721-10 at 190 °C;(f) a cross-over point ranging from > 0.2 rad / s and < 0.5 rad / s, preferably > 0.25 rad / s and < 0.4 rad / s, wherein cross-over point is defined as the shear rate at which the loss modulus (G”) equals storage modulus (G’);(g) a tan delta (100 rad / s) of > 0.4 and < 0.62, wherein tan delta (100 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 100 rad / s in accordance with ISO 6721-10 at 190 °C;(h) a tan delta (10 rad / s) of > 0.65 and < 0.75; wherein tan delta (10 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at @ 10 rad / s in accordance with ISO 6721-10 at 190 °C;(i) a tan delta (1.0 rad / s) of > 0.75 and < 0.9; wherein tan delta (1.0 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 1.0 rad / s in accordance with ISO 6721-10 at 190 °C;(j) a complex viscosity (T|IOO) at a shear rate of 100 rad / s of > 780.0 Pa.s and < 910.0 Pa.s, preferably > 800.0 Pa.s and < 900.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C;(k) a complex viscosity (r|o i) at a shear rate of 0.1 rad / s between > 48000.0 Pa.s and < 66000.0 Pa.s, preferably > 50000.0 Pa.s and < 60000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; (l) a complex viscosity (r|i O) at a shear rate of 1.0 rad / s of > 12000.0 Pa.s and < 16000.0 Pa.s, preferably > 14000.0 Pa.s and < 15000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and (m) a ratio of complex viscosity (v]o.oi) to complex viscosity (T|IOO) between > 180.0 and < 230.0, preferably > 190.0 and < 220.0, where complex viscosity (r|o ,OI) is the complex viscosity at a shear rate of 0.01 rad / s and complex viscosity (r|ioo) is complex viscosity at a shear rate of 100 rad / s, each of which determined in accordance with ISO 6721-10 at 190 °C.

[0036] Preferably, wherein the unimodal polyethylene composition has a ratio of complex viscosity (r|o i) to complex viscosity (T|W) between > 10.0 and < 20.0, preferably > 10.0 and < 18.0, where complex viscosity (r|o i) is the complex viscosity at a shear rate of 0.1 rad / s and complex viscosity (r|io) is complex viscosity at a shear rate of 10 rad / s, each of which is determined in accordance with ISO 6721-10 at 190 °C.Weight Average Molecular Weight (Mw) and Z-average Molecular Weight (Mw)

[0037] Preferably, wherein the unimodal polyethylene composition has a molecular weight distribution (Mw / Mn) of > 14.0 and < 25.0, preferably > 14.0 and < 22.0, preferably > 16.0 and < 20.0, where Mw is the weight average molecular weight and Mn is the number average molecular weight, each determined using Gel Permeation Chromatography (GPC) - Multi-Angle Laser Light Scattering (GPC-MALLS). The expression Mw / Mn as used herein means the ratio of Mw to Mn, where Mw and Mn are as defined.

[0038] Preferably, wherein the unimodal polyethylene composition has a ratio of Z-average molecular weight (Mz) to weight average molecular weight of (Mw) between > 4.0 and < 10.0, preferably > 4.0 and < 8.0, wherein Mw and Mz is determined using Gel Permeation Chromatography(GPC) - MultiAngle Laser Light Scattering.

[0039] Preferably, the unimodal polyethylene composition has:(a) a density of > 915.0 and < 925.0 kg / m3, determined in accordance with ASTM D1505;(b) a melt flow rate of (MFR2ie) of > 0.19 and < 0.23 g / 10 min, preferably > 0.2 and < 0.23 g / 10 min, determined in accordance with ASTM D1238 at 190 °C and measured at 2.16 kg;(c) a weight average molecular weight of (Mw) of > 400 kg / mol and < 425 kg / mol, preferably > 410 kg / mol and < 425 kg / mol, determined using Gel Permeation Chromatography (GPC) - Multi-Angle Laser Light Scattering;(d) a zero shear viscosity (r]o) of > 550,000.0 Pa.s and < 750,000.0 Pa.s, preferably > 600,000.0 Pa.s and < 700,000.0 Pa.s, preferably > 620,000.0 Pa.s and < 700,000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C;(e) a tan delta (0.01 rad / s) of > 1.0 and <3.5, preferably > 1.0 and < 2.0; wherein tan delta (0.01 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 0.01 rad / s in accordance with ISO 6721-10 at 190 °C;(f) a cross-over point ranging from > 0.2 rad / s and < 0.5 rad / s, preferably > 0.25 rad / s and < 0.4 rad / s, wherein cross-over point is defined as the shear rate at which the loss modulus (G”) equals storage modulus (G’);(g) a tan delta (100 rad / s) of > 0.4 and < 0.62, wherein tan delta (100 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 100 rad / s in accordance with ISO 6721-10 at 190 °C;(h) a tan delta (10 rad / s) of > 0.65 and < 0.75; wherein tan delta (10 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 10 rad / s in accordance with ISO 6721-10 at 190 °C;(i) a tan delta (1.0 rad / s) of > 0.75 and < 0.9; wherein tan delta (1.0 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 1.0 rad / s in accordance with ISO 6721-10 at 190 °C;(j) a complex viscosity (T|IOO) at a shear rate of 100 rad / s of > 780.0 Pa.s and < 910.0 Pa.s, preferably > 800.0 Pa.s and < 900.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C;(k) a complex viscosity (r]o I) at a shear rate of 0.1 rad / s between > 48000.0 Pa.s and < 66000.0 Pa.s, preferably > 50000.0 Pa.s and < 60000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; (l) a complex viscosity (T|I.O) at a shear rate of 1.0 rad / s of > 12000.0 Pa.s and < 16000.0 Pa.s, preferably > 14000.0 Pa.s and < 15000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; (m) a ratio of complex viscosity (r]o.oi) to complex viscosity (T|IOO) between > 180.0 and < 230.0, preferably > 190.0 and < 220.0, where complex viscosity (r]o.oi) is the complex viscosity at a shear rate of0.01 rad / s and complex viscosity (r|ioo) is complex viscosity at a shear rate of 100 rad / s, each of which determined in accordance with ISO 6721-10 at 190 °C;(n) a molecular weight distribution (Mw / Mn) of > 14.0 and < 25.0, preferably > 14.0 and < 22.0, preferably > 16.0 and < 20.0, where Mw is the weight average molecular weight and Mn is the number average molecular weight determined using Gel Permeation Chromatography (GPC) - Multi-Angle Laser Light Scattering; and(o) a ratio of Z-average molecular weight (Mz) to weight average molecular weight of (Mw) between > 4.0 and < 10.0, preferably > 4.0 and < 8.0, wherein Mw and Mz determined using Gel Permeation Chromatography(GPC) - Multi -Angle Laser Light Scattering.Short-chain Branching / Methyl Branch / Long Chain Branching Index

[0040] Preferably, wherein the unimodal polyethylene composition has a number of methyl branch per 1000 carbon atoms (CH3 / 1000) of > 1.0 and < 4.0, preferably > 1.5 and < 3.0, preferably > 2.0 and < 3.0, wherein the methyl branch / 1000 carbon atoms is determined with13C NMR spectroscopy.

[0041] Preferably, the unimodal polyethylene composition has:(a) a density of > 915.0 and < 925.0 kg / m3, determined in accordance with ASTM D1505;(b) a melt flow rate of (MFR2ie) of > 0.19 and < 0.23 g / 10 min, preferably > 0.2 and < 0.23 g / 10 min, determined in accordance with ASTM D1238 at 190 °C and measured at 2.16 kg;(c) a weight average molecular weight of (Mw) of > 400 kg / mol and < 425 kg / mol, preferably > 410 kg / mol and < 425 kg / mol, determined using Gel Permeation Chromatography (GPC) - Multi-Angle Laser Light Scattering;(d) a zero shear viscosity (r]o) of > 550,000.0 Pa.s and < 750,000.0 Pa.s, preferably > 600,000.0 Pa.s and < 700,000.0 Pa.s, preferably > 620,000.0 Pa.s and < 700,000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C;(e) a tan delta (0.01 rad / s) of > 1.0 and <3.5, preferably > 1.0 and < 2.0; wherein tan delta (0.01 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 0.01 rad / s in accordance with ISO 6721-10 at 190 °C;(f) a cross-over point ranging from > 0.2 rad / s and < 0.5 rad / s, preferably > 0.25 rad / s and < 0.4 rad / s, wherein cross-over point is defined as the shear rate at which the loss modulus (G”) equals storage modulus (G’);(g) a tan delta (100 rad / s) of > 0.4 and < 0.62, wherein tan delta (100 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 100 rad / s in accordance with ISO 6721-10 at 190 °C;(h) a tan delta (10 rad / s) of > 0.65 and < 0.75; wherein tan delta (10 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 10 rad / s in accordance with ISO 6721-10 at 190 °C;(i) a tan delta (1.0 rad / s) of > 0.75 and < 0.9; wherein tan delta (1.0 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 1.0 rad / s in accordance with ISO 6721-10 at 190 °C;(j) a complex viscosity (T|IOO) at a shear rate of 100 rad / s of > 780.0 Pa.s and < 910.0 Pa.s, preferably > 800.0 Pa.s and < 900.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C;(k) a complex viscosity (r|o i) at a shear rate of 0.1 rad / s between > 48000.0 Pa.s and < 66000.0 Pa.s, preferably > 50000.0 Pa.s and < 60000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; (l) a complex viscosity (ip O) at a shear rate of 1.0 rad / s of > 12000.0 Pa.s and < 16000.0 Pa.s, preferably > 14000.0 Pa.s and < 15000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and (m) a ratio of complex viscosity (r]o.oi) to complex viscosity (T|IOO) between > 180.0 and < 230.0, preferably > 190.0 and < 220.0, where complex viscosity (r|o ,OI) is the complex viscosity at a shear rate of 0.01 rad / s and complex viscosity (r]ioo) is complex viscosity at a shear rate of 100 rad / s, each of which determined in accordance with ISO 6721-10 at 190 °C;(n) a molecular weight distribution (Mw / Mn) of > 14.0 and < 25.0, preferably > 14.0 and < 22.0, preferably > 16.0 and < 20.0, where Mw is the weight average molecular weight and Mn is the number average molecular weight determined using Gel Permeation Chromatography(GPC) - Multi-Angle Laser Light Scattering;(o) a ratio of Z-average molecular weight (Mz) to weight average molecular weight of (Mw) between > 4.0 and < 10.0, preferably > 4.0 and < 8.0, wherein Mw and Mz determined using Gel Permeation Chromatography(GPC) - Multi-Angle Laser Light Scattering;(p) a number of methyl branch per 1000 carbon atoms (CH3 / IOOO) of > 1.0 and < 4.0, preferably > 1.5 and < 3.0, preferably > 2.0 and < 3.0, wherein the methyl branch / 1000 carbon atoms is determined with13C NMR spectroscopy;(q) a melt strength of > 6.0 cN and < 10.0 cN, preferably > 6.5 cN and < 8.0 cN, wherein the melt strength is determined at 190 °C with a capillary rheometer equipped with a take-up unit;(r) satisfies the following equation - 3.6xl013x Mw34< r|o< 5.0xl012x Mw34, where (r]o) is the zeroshear viscosity (T|O) expressed in the unit of Poise and Mw is the weight average molecular weight, as measured by GPC-MALLS, expressed in the units of g / mol; and(s) a number of methyl branch per 1000 carbon atoms (CH3 / IOOO) of > 1.0 and < 4.0, preferably > 1.5 and < 3.0, preferably > 2.0 and < 3.0, wherein the number of methyl branch / 1000 carbon atoms is determined with13C NMR spectroscopy.

[0042] Preferably wherein the unimodal polyethylene composition has a number of short chain branching (SCB) per thousand carbon atoms (SCB / 1000) of > 15.0 and < 22.0, when determined using13C NMR spectroscopy; and / or wherein the unimodal polyethylene composition has a long-chain branching index (LCBI) of > 0.1 and < 0.35, preferably > 0.2 and < 0.3; wherein LCBI is the ratio of the measured mean-square radius of gyration Rg, measured by GPC-MALLS, to the mean- square radius of gyration for a linear ethylene polymer where the ethylene polymer of the unimodal composition and the linear ethylene polymer has a molecular weight of 106g / mol.

[0043] Preferably, the unimodal polyethylene composition has:(a) a density of > 915.0 and < 925.0 kg / m3, determined in accordance with ASTM D1505;(b) a melt flow rate of (MFR2 ie) of > 0.2 and < 0.23 g / 10 min, determined in accordance with ASTM D1238 at 190 °C and measured at 2.16 kg;(c) a weight average molecular weight of (Mw) of > 410 kg / mol and < 425 kg / mol, determined using Gel Permeation Chromatography (GPC) - Multi-Angle Laser Light Scattering;(d) a zero shear viscosity (r]o) of > 620,000.0 Pa.s and < 700,000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C;(e) atan delta (0.01 rad / s) of > 1.0 and < 2.0; wherein tan delta (0.01 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 0.01 rad / s in accordance with ISO 6721-10 at 190 °C;(f) a cross-over point ranging from > 0.25 rad / s and < 0.4 rad / s, wherein cross-over point is defined as the shear rate at which the loss modulus (G”) equals storage modulus (G’);(g) atan delta (100 rad / s) of > 0.4 and < 0.62, wherein tan delta (100 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 100 rad / s in accordance with ISO 6721-10 at 190 °C;(h) a tan delta (10 rad / s) of > 0.65 and < 0.75; wherein tan delta (10 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 10 rad / s in accordance with ISO 6721-10 at 190 °C;(i) atan delta (1.0 rad / s) of > 0.75 and < 0.9; wherein tan delta (1.0 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 1.0 rad / s in accordance with ISO 6721-10 at 190 °C;(j) a complex viscosity (r]ioo) at a shear rate of 100 rad / s of > 800.0 Pa.s and < 900.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C;(k) a complex viscosity (T]0I) at a shear rate of 0.1 rad / s between > 50000.0 Pa.s and < 60000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C;(l) a complex viscosity (T]I O) at a shear rate of 1.0 rad / s of > 14000.0 Pa.s and < 15000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C;(m) a ratio of complex viscosity (r|o ,OI) to complex viscosity (T|IOO) between > 190.0 and < 220.0, where complex viscosity (r|o ,OI) is the complex viscosity at a shear rate of 0.01 rad / s and complex viscosity (r]ioo) is complex viscosity at a shear rate of 100 rad / s, each of which determined in accordance with ISO 6721-10 at 190 °C;(n) a molecular weight distribution (Mw / Mn) of > 16.0 and < 20.0, where Mw is the weight average molecular weight and Mn is the number average molecular weight determined using Gel Permeation Chromatography(GPC) - Multi-Angle Laser Light Scattering;(o) a ratio of Z-average molecular weight (Mz) to weight average molecular weight of (Mw) between > 4.0 and < 8.0, wherein Mw and Mz determined using Gel Permeation Chromatography(GPC) - MultiAngle Laser Light Scattering;(p) a number of methyl branch per 1000 carbon atoms (CH3 / IOOO) of > 2.0 and < 3.0, wherein the methyl branch / 1000 carbon atoms is determined with13C NMR spectroscopy;(q) a melt strength of > 6.5 cN and < 8.0 cN, wherein the melt strength is determined at 190 °C with a capillary rheometer equipped with a take-up unit;(r) satisfies the following equation - 3.6xl013x Mw34< r|0< 5.0xl012x Mw34, where (r]0) is the zeroshear viscosity (r]0) expressed in the unit of Poise and Mw is the weight average molecular weight, as measured by GPC-MALLS, expressed in the units of g / mol;(s) a number of methyl branch per 1000 carbon atoms (CH3 / IOOO) of > 2.0 and < 3.0, wherein the methyl branch / 1000 carbon atoms is determined with13C NMR spectroscopy;(t) a number of short chain branching (SCB) per thousand carbon atoms (SCB / 1000) of > 15.0 and < 22.0, when determined using NMR spectroscopy; and(u) a long-chain branching index (LCBI) of > 0.1 and < 0.35, preferably > 0.2 and < 0.3; wherein LCBI is the ratio of the measured mean-square radius of gyration Rg, measured by GPC-MALLS, to the meansquare radius of gyration for a linear ethylene polymer where the ethylene polymer of the unimodal composition and the linear ethylene polymer has a molecular weight of 106g / mol.Strain Hardening Modulus

[0044] The polyethylene composition of the present invention demonstrates suitable strain hardening modulus. The increase of elongational viscosity as a function of time or strain is defined asstrain hardening (Stadler, F.J., Kaschta, J., Miinstedt, H. et al. Influence of molar mass distribution and long-chain branching on strain hardening of low density polyethylene, (2009) Rheol Acta, 48, pp. 479 - 490, DOI: 10.1007 / sOO 397 -008-0334-8). Strain hardening imparts processability especially bubble stability during fdm blowing.

[0045] One way to quantify the level of strain hardening is the strain hardening modulus <Gp>, following ISO 18488:2015.

[0046] Accordingly in an aspect of the invention, the unimodal polyethylene composition has a strain hardening modulus of > 19.5 and < 23.0 MPa, preferably > 19.5 and < 22.0 MPa determined in accordance with ISO 18488:2015.Ethylene polymer and Polyethylene Composition Production

[0047] In an aspect of the invention, the invention relates to a process for preparing the unimodal polyethylene composition of the present invention. The process comprises a step of polymerizing ethylene monomer in a tubular reactor.

[0048] The ethylene polymer may be produced via a high-pressure free-radical polymerization process with typical steps of initiation (as a result of dissociation of chemical initiator to form free radicals), propagation (addition of free radicals to the double bond of ethylene monomer), chain transfer (transference of radical center from a living polymer towards another group) and termination (two macroradicals react to form dead polymer).

[0049] The chain transfer reactions for example are responsible for the formation of branching. Intramolecular chain transfer reactions result in SCB, whereas intermolecular chain transfer reactions may generate SCB and LCB. As a result of both reactions, branches with varying length are formed. The type of reactor employed for the polymerization of ethylene, as well as the reaction conditions, may influence the molar mass and branching distribution.

[0050] Examples of chain transfer agents include tetramethylsilane, cyclopropane, sulfur hexafluoride, methane, t-butanol, perfluoropropane, deuterobenzene, ethane, ethylene oxide, 2,2-dimethylpropane, benzene, dimethyl sulfoxide, vinyl methyl ether, methanol, propane, 2-methyl-3-buten-2-ol, methyl acetate, t-butyl acetate, methyl formate, ethyl acetate, butane, triphenylphosphine, methylamine, methyl benzoate, ethyl benzoate, N,N-diisopropylacetamide, 2,2,4-trimethylpentane, n-hexane, isobutane, dimethoxymethane, ethanol, n-heptane, n-butyl acetate, cyclohexane, methylcyclohexane, 1,2-dichloroethane, acetonitrile, N-ethylacetamide, propylene, n-decane, N,N-diethylacetamide, cyclopentane, acetic anhydride, n-tridecane, n-butyl benzoate, isopropanol, toluene,hydrogen, acetone, 4,4-dimethylpentene-l, trimethylamine, N,N-dimethylacetamide, isobutylene, n-butyl isocyanate, methyl butyrate, n-butylamine, N,N-dimethylformamide, diethyl sulfide, diisobutylene, tetrahydrofuran, 4-methylpentene-l, p-xylene, p-dioxane, trimethylamine, butene-2, 1 -bromo-2-chlorethane, octene- 1, 2-methylbutene-2, cumene, butene- 1, methyl vinyl sulfide, n-butyronitrile, 2-methylbutene-1, ethylbenzene, n-hexadecene, 2-butanone, n-butyl isothiocyanate, methyl 3-cyanopropionate, tri-n- butylamine, 3-methyl-2-butanone, isobutyronitrile, di-n-butylamine, methyl chloroacetate, 3-methylbutene-l, 1 ,2-dibromoethane, dimethylamine, benzaldehyde, chloroform, 2-ethylhexene-1, propionaldehyde, 1,4 dichlorobutene-2, tri-n-butylphosphine, dimethylphosphine, methyl cyanoacetate, carbon tetrachloride, bromotrichloromethane, di-n- butylphosphine, acetaldehyde, and phosphine.

[0051] Examples of suitable initiators include peresters including but not limited to bis(2 ethylhexyl)peroxydicarbonate, tert-Butyl per(2-ethyl)hexanoate, tert-Butyl perpivalate, tert-Butyl pemeodecanoate, tert-Butyl perisobutyrate, tert-Butyl per-3, 5, 5, -trimethylhexanoate, tert-Butyl perbenzoate, and dialkyl peroxides including but not limited to di-tert-butyl peroxide.

[0052] In the present invention, the ethylene polymer is produced using tubular reactor systems.

[0053] The tubular reactor system employed may for example be comprise of a system of two compressors (primary and secondary compressors), a pre-heater, the tubular reactor, a set of two separators (high- and low-pressure separators) and feeding units for monomer and initiator. During the operation of the system, the monomer may be supplied entirely at the beginning of the tubular reactor or supplied both at the beginning and through different injection points located downstream in the tubular reactor. In either case, the ethylene added at the inlet of the tubular reactor may be first compressed by the primary compressor to a pressure between 25 to 30 MPa. The chain transfer agent is also added via the primary compressor. The secondary compressor may elevate the pressure to values between 200 MPa to 350 MPa, which may correspond to the reactor operation pressure.

[0054] The pre-heater may be operated at a temperature of around 120 C to 220 °C to start the reaction. The tubular reactor is where the highly exothermic polymerization takes place, undergoing temperatures between 120 to 330 °C. The tubular reactor has typically a length from 200 to 1600 meters and diameter from 20 to 100 mm. Several injection points along the tube may be installed to add monomer and / or initiator. The initiator could comprise a single type or a mixture of different initiator types.

[0055] At the end of the reactor, a high-pressure separator is located in order to separate the mixture of polymer and monomer and other low-molar mass compounds. The ethylene recovered from the high-pressure separator is re-introduced between the primary and high-pressure compressor. A second separator operating at low pressure is located downstream to the high-pressure separated. The ethylene recovered from the low-pressure separator may be reintroduced into the system via the primary compressor.

[0056] The ethylene polymer obtained may be compounded with additives in a melt extruder to obtain the polyethylene composition.Film comprising the polyethylene composition

[0057] In aspect of the invention, the invention relates to a film comprising the unimodal polyethylene composition according to the present invention. Preferably, the film comprises > 95.0 wt.%, preferably > 96.0 wt.%, preferably > 99.0 wt.%, preferably 100 wt.% of the unimodal polyethylene composition.

[0058] Preferably wherein the film has:(a) a protrusion puncture resistance of > 30.0 N and < 40.0 N, preferably > 32.0 N and < 38.0 N determined in accordance with ASTM D 5748;(b) a tensile strength at break in machine direction (MD) of > 23.0 MPa and < 30.0 MPa determined in accordance with ASTM D 882;(c) a dart impact resistance of > 3.5 g / pm and < 5.0 g / pm determined in accordance with ASTM D 1709; and(d) a shrinkage after seven minutes in the machine direction (MD) of > 70% and < 80%, determined in accordance with GB / T 13519-2016.

[0059] The film may be produced by a film blowing process. The process is the same as a regular extrusion process up until the die. The extrusion process can be attained by a single screw or a double screw extruder. The die is an upright cylinder with a circular opening similar to that of a pipe die . The polyethylene pellets may be fed into the extruder barrel through a metered feeder at a constant mass flow rate. The extruder screws are driven by a motor, and its speed can be changed as desired. The pellets melt in the extruder and then the melt is pushed out through an adaptor die located at the exit of the extruder. The melt then flows through a melt pump, which supplies the molten polyethylene to the die at a constant mass flow rate. This melt then flows through the die channel and squeezes out through the die opening.

[0060] The molten polyethylene may be then pulled upwards from the die by a pair of nip rolls high above the die. In the center of the die there is an air inlet from which compressed air can be forced into the center of the extruded circular profile, creating a bubble. This expands the extruded circular cross section by some ratio (a multiple of the die diameter), thus decreasing the wall thickness. This ratio is called the “blow-up ratio.” There is also an external air cooling ring attached to the die, which cools the bubble from the outer surface. The nip rolls flatten the bubble into a double layer film. This film is then spooled on a drum.

[0061] The invention will now be demonstrated with the following non-limiting examples.EXAMPLES

[0062] Purpose: To evaluate the properties of sample specimen prepared from the polyethylene composition of the present invention in comparison to existing samples.

[0063] Process of preparing the polyethylene composition: The following process parameters were followed while producing the polyethylene compositions using a tubular polymerization process. The process involved the use of a tubular polymerization reactor with two compressors (primary and secondary compressors) positioned upstream to the polymerization reactor. The product separators were positioned downstream to the polymerization reactor.

[0064] Two separators (to separate monomer / polymer mixture leaving the tubular reactor): the ethylene separated from the monomer-polymer mixture was recycled to the ethylene-feed between the primary compressor and the secondary compressor. The two separators were used to split the monomer / polymer mixture leaving the tubular reactor. The product separators were positioned downstream to the polymerization reactor. The ethylene separated from the monomerpolymer mixture was recycled to the ethylene-feed between the primary compressor and the secondary compressor. The low-pressure separator was used to add of fresh supply of ethylene before being fed to the primary compressor

[0065] Low pressure separator: the low-pressure separator, was used to add of fresh supply of ethylene before being fed to the primary compressor.

[0066] Monomer supply to the tubular reactor was carried out at the reactor inlet. The ethylene monomer was introduced at a pressure of 1.7 MPa.

[0067] Initiator feed: introduced the initiators in multiple places in the reactor, thus creating multiple reaction zones. There are 4 injection points creating 4 different reaction zones. The conditions of temperature and pressure is provided under Table la.Table 1

[0068] The use of a plurality of initiator inlets allowed obtaining a LDPE with broad molar mass distribution, enhanced long chain branching and higher conversion without the need of increasing the length of the reactor. In each injection point, one or more chemical initiators could be used. In the present invention, four injection points were used, using peroxide mixtures containing tert-butyl -peroxy-2-ethylhexonoate (TBPEH), tert-butyl -peroxybenzoate (TBPB), and di-tert-butylperoxide (DTBP),. Propylene was added as chain transfer agent.Table la - Tubular reactor conditions

[0069] The monomer supply to the tubular reactor can be carried out at the reactor inlet only or in combination of reactor inlet and one or more reactor sides streams. In the current example, the monomer was fed via the reactor inlet with a pressure in the primary compressor of 25 MPa, and 260 MPa in the secondary compressor. Without being bound by any theory, it is believed that the operating pressure used was suitable in order to promote long chain branching. At this suitable operating pressure, ethylene concentration decreases as the ethylene density reduces at these conditions. Thus, the ratio of intermolecular chain transfer reaction over propagation increases, as well as the branching density and molar mass distribution, which in turn enhances melt strength.

[0070] IE1 represented a sample were prepared from the inventive polyethylene composition while the samples CE1-CE7 are comparative samples.

[0071] CE1-CE3 are grades procured from SABIC. CE4-CE7 are commercial grade available in the market.

[0072] The results for IE1-CE3 are provided below:Table 2

[0073] Further rheological parameters for the samples IE1-CE3 are as follows:Table 3" " " ""

[0074] Results for the samples IE1-CE3 are as follows:Table 4< <<<

[0075] Results provided for the comparative examples CE4-CE7 :Table 5

[0076] Results for rheological properties provided for the comparative examples CE4-CE7 :Table 6" " " " "

[0077] Additional results are as provided below CE4-CE7 are as below:Table 7< <<<*Where r]0represents zero-shear viscosity,

[0078] Tests Methodology followed:

[0079] GPC-MALLS: Gel Permeation Chromatography(GPC) - Multi -Angle Laser Light Scattering (GPC-MALLS) was employed to determine the molecular mass distribution. Using GPC, the macromolecules were separated according to hydrodynamic volume. In combination with light scattering, the angular scattering distribution was determined at each retention volume. The procedure followed is as described in Tackx & Tacx (1) for low-density polyethylene. The polymer samples were dissolved in 1,2,4-trichlorobenzene (TCB) and stabilized with butylhydroxytoluene (also known as 2,6-di-tert-butyl-4-methylphenol or BHT) at a concentration of 1 g / L. (Tackx P.,Chain architecture ofLDPE as a function of molar mass using size exclusion chromatography and multi-angle laser light scattering (SEC-MALLS), (1998) Polymer, 39 (14), pp. 3109 - 3113, DOI: 10.1016 / 80032-3861(97)10098-2).

[0080] The separation of the polymer according to molar mass was performed with a GPC system, employing two Polymer Laboratories GPC column (20pm PLMixed ALS, 300 x 7.5 mm). The system was used with an injection volume of 200pl and flowrate of 0.5 ml / min. Detectors (concentration detector PolymerChar IR5 and light scattering detector, Wyatt Dawn Helios 18 angles) and columns were operated at 160°C.

[0081] Molar mass was determined from the intensity of scattered light at zero scattering angle along with the concentration; intensity at zero angle was obtained by the extrapolation to zero of intensitiesmeasured at several different angles, and concentration was typically measured with an IR5 detector, inline with the MALS detector. RMS radius was calculated from the slope of the angular variation of the scattered light intensity.

[0082] NMR: The samples were dissolved at 130°C in C2D2CI4 containing DBPC as stabilizer. The 1H and 13C NMR spectra was recorded on a Bruker Avance500 spectrometer equipped with a cryogenic cooled probe head operating at 125°C.

[0083] Dynamic Mechanical Analysis (DMA): tests were conducted using an Anton Paar rheometer MCR502 with a parallel plate geometry using 25mm diameter and 1 mm gap at 190° C. A 5.0 % strain under an inert nitrogen atmosphere within the linear viscoelastic region was used to perform the frequency sweep test in the range of 0.01 to 100 rad s ' at 5 points per decade logarithmically spaced to determine viscoelastic spectra under small amplitude oscillatory shear measurements.

[0084] The stress response was analyzed in terms of amplitude and phase, from which the storage modulus (G'), loss modulus (G"), complex modulus (G*), tan delta, and complex viscosity (q*) were calculated. The complex modulus, G*, is a complex number with G' as its real and G" as its imaginary components, respectively (G*=G'±iG"). The magnitude of G* is reported as |G*|=(G'2+G"2)1 2. Both the storage modulus and tan delta are related to the material's relative elasticity. Tan delta is the ratio of the loss modulus to the storage modulus.

[0085] The Zero Shear Viscosity (ZSV) is the plateau viscosity at low enough shear rate (angular frequency). It was determined by fitting the 3 -parameter Cross model on the complex viscosity versus angular frequency with data obtained in accordance with ISO 6721-10 at 190 °C. In other words, the Zero Shear Viscosity is measured in accordance with ISO 6721-10 at 190 °C and using the Cross-model equation. The Cross-model equation describes the viscosity curve of a material with Newtonian regions at low shear rates and a shear thinning (power law) region at medium shear rates. Fitting is done by Rheoplus or Rheocompass software by Equation (1):Where:co angular frequency in rad / s / / * is the complex viscosity in Pa- s7 o zero shear viscosity in Pa sn shear thinning parameter [ - ]2 relaxation time in s.

[0086] Melt Strength: Melt strength was determined at 190 °C with a capillary rheometer equipped with a take-up unit.

[0087] In particular, the experimental set-up for the evaluation of melt strength consisted of a CEAST Rheologic 2500 capillary rheometer (Instron, 30 mm capillary length, 1 mm capillary diameter) equipped with a take-up unit. The take-up unit comprises of a series of pulleys which stretched the polymer strand at specified speed (take-up speed) and at a controlled acceleration. The required tensile force to elongate the strand was recorded as a function of the take-up speed. With this set-up, the samples were stretched in uniaxial extension.

[0088] The piston speed was 0.049 mm / s, with a load cell of lOkN and a throughput of 0.25 g / min. The pre-heating time was 300 seconds, at the temperature specified for the test (190 °C). The start-speed of the pulley was 7 mm / s, with an acceleration of 1.2 mm / s2with a distance between die and first wheel of 23.5 cm, and 9.5 cm between the first wheel and the pulley system. The polymer strand was cooled by ambient air. The melt strength was defined as the maximum tensile force recorded during the test. For each sample, at least five force-speed traces were recorded.

[0089] In other words, melt strength was determined at 190 °C with a capillary rheometer equipped with a take-up unit comprising of a series of pulleys which stretched the polymer strand at specified speed (take-up speed) and at a controlled acceleration. Melt strength measurement involved measuring the tensile force in the uniaxial stretching of the polyethylene strand using a capillary rheometer equipped with the take-up unit, comprising a series of pulleys that stretched the polymer strand at a start-speed of 7.0 mm / s, with an acceleration of 1.2 mm / s2, and a piston speed of 0.049 mm / s, with a load cell of lOkN and at a throughput of 0.25 g / min.

[0090] Density: was determined in accordance with ASTM DI 505 at 23 °C.

[0091] Strain Hardening: The procedure followed was ISO 18488:2015. In particular, the materials were pressed at 160 °C to a sheet with a thickness of 300 mm. The procedure for pressing was: 5 min heating up at 0 kN load, 3 min at 10 kN load, 3 min at 50 kN load and cooling down to room temperature at a load of 180 kN. After pressing, the samples were annealed for 1 h at 85 °C and then slowly cooled down to room temperature by switching off the temperature chamber. Finally, the test specimens (ISO37 type 3) were punched from the pressed sheets.

[0092] The measurement is in principle a standard tensile test. The test specimen was extended along its major axis at constant speed (20 mm / min) at 80 °C until the strain reaches around 750%. Themaximum strain value was limited by the length of the temperature chamber and the maximum strain before break of the sample. During the test, the load sustained by the specimen and the elongation are measured. The elongation is determined with an optical extensometer. Therefore, two reflecting and self-adhesive gauge marks were attached to the test specimens. The initial distance between these marks (gauge length) was determined after reaching the pre-load before each test. Prior to testing the test specimen were kept for about 30 min in the temperature chamber at the envisaged test temperature to allow thermal equilibrium.

[0093] The strain hardening part of the curve was visually determined by observation of the neck propagation, and below the maximum draw ratio. The calculation of <(i >. which indicated the slope of the strain hardening part of a stress-strain curve, was performed typically between draw ratio’s 4 and 7 for this study. <GP> and is expressed in MPa.Mechanical Properties of a film Sample: Mechanical Properties of Film samples:

[0094] Samples comprising the polyethylene composition were extruded using a commercial blown extrusion lab line from Collin, equipped with a 30 mm single screw extruder and an L / D of 30. The extrusion was run at a throughput of 10 kg / h and a blow-up ratio of 3.0. The monoweb samples of the resultant film sample had a thickness of 40 microns.

[0095] The film sample were subjected to various mechanical tests as reported below - Table 8

[0096] Mechanical Properties of a film Sample: For samples CE4-CE7Table 9

[0097] From the experimental data it is evident that the polyethylene composition (IE 1 ) over that of the comparative example (CE1-CE7) has a balance of high melt strength, desired rheological properties for processability while imparting a suitable mechanical properties such as tensile and puncture resistance to a film produced from such a composition. For example, the sample IE1 has high melt strength but also sufficiently low cross-overpoint indicating not only suitability for film production with high bubble stability but also enhanced processability. Further, the sample IE1 also demonstrated suitable shear thinning indicated by the values of [r| (0.01) / p (100)], indicating suitable processability as well.

[0098] In addition, the film sample prepared from the inventive polyethylene sample (IE1) has suitable balance of puncture resistance, tensile properties, shrink properties while imparting desired melt strength during film production. For example, the values of protrusion puncture resistance, dart impact resistance and tensile strength for the sample IE1 is comparable if not higher in comparison to some of the comparative samples.

Claims

CLAIMS1. A unimodal polyethylene composition, comprising > 97.0 wt.% with regard to the total weight of the polyethylene composition, of an ethylene polymer, wherein the unimodal polyethylene composition has:(a) a density of > 915.0 and < 930.0 kg / m3, preferably > 915.0 and < 925.0 kg / m3, determined in accordance with ASTM DI 505;(b) a melt flow rate of (MFR216) of > 0.17 and < 0.25 g / 10 min, preferably > 0.18 and < 0.24 g / 10 min, preferably > 0.19 and < 0.23 g / 10 min, preferably > 0.2 and < 0.23 g / 10 min, determined in accordance with ASTM D1238 at 190 °C and measured at 2.16 kg;(c) a weight average molecular weight of (Mw) of > 350 kg / mol and < 450 kg / mol, preferably > 380 kg / mol and < 430 kg / mol, preferably > 400 kg / mol and < 425 kg / mol, preferably > 410 kg / mol and < 425 kg / mol, determined using Gel Permeation Chromatography(GPC) - Multi-Angle Laser Light Scattering (GPC-MALLS);(d) a zero shear viscosity (r]o) of > 550,000.0 Pa.s and < 750,000.0 Pa.s, preferably > 600,000.0 Pa.s and < 700,000.0 Pa.s, preferably > 620,000.0 Pa.s and < 700,000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and(e) a tan delta (0.01 rad / s) of > 1.0 and < 3.5, preferably > 1.0 and < 2.0; wherein tan delta (0.01 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 0.01 rad / s in accordance with ISO 6721-10 at 190 °C.

2. The unimodal polyethylene composition of claim 1, wherein the unimodal polyethylene composition has a cross-over point ranging from > 0.2 rad / s and < 0.5 rad / s, preferably > 0.25 rad / s and < 0.4 rad / s, wherein cross-over point is defined as the shear rate at which the loss modulus (G”) equals storage modulus (G’).

3. The unimodal polyethylene composition according to anyone of claims 1-2,(a) wherein the unimodal polyethylene composition has a tan delta (100 rad / s) of > 0.4 and < 0.65; preferably > 0.4 and < 0.62, wherein tan delta (100 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 100 rad / s in accordance with ISO 6721-10 at 190 °C; and / or(b) wherein the unimodal polyethylene composition has a tan delta (10 rad / s) of > 0.65 and < 0.75; wherein tan delta (10 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 10 rad / s in accordance with ISO 6721-10 at 190 °C; and / or(c) wherein the unimodal polyethylene composition has a tan delta (1.0 rad / s) of > 0.75 and < 0.9; wherein tan delta (1.0 rad / s) is the ratio of loss modulus (G”) to storage modulus (G’) with each of loss modulus (G”) and storage modulus (G’) is determined at 1.0 rad / s in accordance with ISO 6721-10 at 190 °C.

4. The unimodal polyethylene composition according to anyone of claims 1-3, wherein the unimodal polyethylene composition has a strain hardening modulus of > 19.5 and < 23.0 MPa, preferably > 19.5 and < 22.0 MPa determined in accordance with ISO 18488:2015.

5. The unimodal polyethylene composition according to anyone of claims 1-4,(a) wherein the unimodal polyethylene composition has a complex viscosity (r]ioo) at a shear rate of 100 rad / s of > 780.0 Pa.s and < 910.0 Pa.s, preferably > 800.0 Pa.s and < 900.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and / or(b) wherein the unimodal polyethylene composition has a complex viscosity (r|o i) at a shear rate of 0.1 rad / s between > 48000.0 Pa.s and < 66000.0 Pa.s, preferably > 50000.0 Pa.s and < 60000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C; and / or (c) wherein the unimodal polyethylene composition has a complex viscosity (r|i o) at a shear rate of 1.0 rad / s of > 12000.0 Pa.s and < 16000.0 Pa.s, preferably > 14000.0 Pa.s and < 15000.0 Pa.s, determined in accordance with ISO 6721-10 at 190 °C.

6. The unimodal polyethylene composition according to anyone of claims 1-5, wherein the unimodal polyethylene composition has a ratio of complex viscosity (r]ooi) to complex viscosity (r]ioo) between > 180.0 and < 230.0, preferably > 190.0 and < 220.0, where complex viscosity (r]o.oi) is the complex viscosity at a shear rate of 0.01 rad / s and complex viscosity (T|IOO) is complex viscosity at a shear rate of 100 rad / s, each of which is determined in accordance with ISO 6721-10 at 190 °C.

7. The unimodal polyethylene composition according to anyone of claims 1-6, wherein the unimodal polyethylene composition has a ratio of complex viscosity (r|o i) to complex viscosity (r|io) between > 10.0 and < 20.0, preferably > 10.0 and < 18.0, where complex viscosity (r|o i) is the complex viscosity at a shear rate of 0.1 rad / s and complex viscosity (r|io) is complex viscosity at a shear rate of 10 rad / s, each of which is determined in accordance with ISO 6721-10 at 190 °C.

8. The unimodal polyethylene composition according to anyone of claims 1-7, wherein the unimodal polyethylene composition has a molecular weight distribution (Mw / Mn) of > 14.0 and < 25.0, preferably > 14.0 and < 22.0, preferably > 16.0 and < 20.0, where Mw is the weight average molecular weight and Mn is the number average molecular weight each determined using Gel Permeation Chromatography(GPC) - Multi -Angle Laser Light Scattering.

9. The unimodal polyethylene composition according to anyone of claims 1-8, wherein the unimodal polyethylene composition has a ratio of Z-average molecular weight (Mz) to weight average molecular weight of (Mw) between > 4.0 and < 10.0, preferably > 4.0 and < 8.0, wherein Mw and Mz are determined using Gel Permeation Chromatography (GPC) - Multi-Angle Laser Light Scattering.

10. The unimodal polyethylene composition according to anyone of claims 1-9,(a) wherein the unimodal polyethylene composition has a melt strength of > 6.0 cN and < 10.0 cN, preferably > 6.5 cN and < 8.0 cN, wherein the melt strength is determined at 190 °C with a capillary rheometer equipped with a take-up unit; and / or(b) wherein the unimodal polyethylene composition satisfies the following equation: 3.6x10"13x Mw34< r|o< 5.0xl0"12x Mw34, where (r]o) is the zero-shear viscosity (T|O) expressed in the unit of Poise and Mw is the weight average molecular weight, as measured by GPC- MALLS, expressed in the units of g / mol.

11. The unimodal polyethylene composition according to anyone of claims 1-10, wherein the unimodal polyethylene composition has a number of methyl branch per 1000 carbon atoms (CH3 / IOOO) of > 1.0 and <4.0, preferably > 1.5 and < 3.0, preferably > 2.0 and < 3.0, wherein the number of methyl branch / 1000 carbon atoms is determined with13C NMR spectroscopy.

12. The unimodal polyethylene composition according to anyone of claims 1-11,(a) wherein the unimodal polyethylene composition has a number of short chain branching (SCB) perthousand carbon atoms (SCB / 1000) of> 15.0 and < 22.0, when determined using NMR spectroscopy; and / or(b) wherein the unimodal polyethylene composition has a long-chain branching index (LCBI) of > 0.1 and < 0.35, preferably > 0.2 and < 0.3; wherein LCBI is the ratio of the measuredmean-square radius of gyration Rg, measured by GPC-MALLS, to the mean- square radius of gyration for a linear ethylene polymer where the ethylene polymer of the unimodal composition and the linear ethylene polymer has a molecular weight of 106g / mol.

13. A process for preparing the unimodal polyethylene composition according to anyone of claims 1- 12, wherein the process comprises a step of polymerizing ethylene monomer in a tubular reactor.

14. A film comprising the unimodal polyethylene composition according to anyone of claims 1-12, preferably wherein the film comprises > 95.0 wt.%, preferably > 96.0 wt.%, preferably > 99.0 wt.%, preferably 100 wt.% of the unimodal polyethylene composition.

15. Use of the unimodal polyethylene composition according to anyone of claims 1-12 in the production of blow films wherein the unimodal polyethylene composition imparts improved bubble stability during the blow film production.

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