POLYETHYLENE COMPOSITIONS AND ARTICLES WITH GOOD BARRIER PROPERTIES

Abstract

A dual-reactor solution polymerization process yields polyethylene compositions containing a first and a second ethylene flake, which offer a balance of barrier properties, toughness, and environmental resistance. These polyethylene compositions are suitable for end-use applications that benefit from low oxygen transmission rates, such as bottle closures or barrier films.

Description

POLYETHYLENE COMPOSITIONS AND ARTICLES WITH GOOD BARRIER PROPERTIES Field of Invention The present invention relates to polyethylene compositions that are useful in the manufacture of articles in which good barrier properties are desirable, such as, for example, bottle closures or barrier films. Background of the Invention Work has been done to develop polyethylene compositions comprising two ethylene homopolymer components in which the selected components are of relatively low and relatively high molecular weight. These ethylene homopolymer compositions, which can have a bimodal molecular weight distribution profile, have been usefully applied in the formation of films having good barrier properties (see, e.g., U.S. Patent Nos. 7,737,220 and 9,587,093, and U.S. Patent Application Publication Nos. 2008 / 0118749, 2009 / 0029182, and 2011 / 0143155). Although polyethylene compositions comprising a first and a second ethylene copolymer of different relative molecular weights and densities have found application in molding applications such as closures (see, e.g., U.S. Pat. Nos. Ref. 319044 9,758,653; 9,074,082; 9,475,927; 9,783,663; 9,783,664; 8,962,755; 9,221,966; 9,371,442 and 8,022,143), less emphasis has so far been placed on the barrier properties of such resins (see, e.g., WO 2016 / 135590). Summary of the Invention We have found that when polyethylene copolymer compositions are properly designed, they can have good barrier properties when produced in, for example, a compression-molded film or an injection-molded closure. An embodiment of the disclosure is a polyethylene copolymer composition comprising: (1) 10 to 70% by weight of a first ethylene copolymer having a melt index I2 of from 0.1 to 10 q / 10 min; a molecular weight distribution Mw / Mnde of less than 3.0; and a density of from 0.910 to 0.946 g / cm3; and (2) 90 to 30% by weight of a second ethylene copolymer having a melt index I2 of from 25 to 1500 g / 10 min; a molecular weight distribution Mw / Mnde of less than 3.0; and a density higher than the density of the first ethylene copolymer, but less than 0.970 g / cm3; wherein the density of the second ethylene copolymer is less than 0.037 g / cm3 higher than the density of the first ethylene copolymer; the ratio (SCB1 / SCB2) of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer (SCB1) to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB2) is greater than 1.0 ; and wherein the polyethylene copolymer composition has a molecular weight distribution from 1.8 to 7.0; a density of less than 0.949 g / cm3; a high load melt index I21 of at least 150 g / 10 min; a weight average molecular weight Z Mz of less than 200,000; a melt flow ratio I21 / I2 of from 20 to 50; a strain exponent of less than 1.40; and an ESCR Condition B (100% Igepal) of at least 3.5 hours; and wherein the polyethylene copolymer composition further comprises a nucleating agent. An embodiment of the disclosure is a closure for bottles, the closure comprising a polyethylene copolymer composition comprising: (1) 10 to 70% by weight of a first ethylene copolymer having a melt index I2 of from 0.1 to 10 g / 10 min; a molecular weight distribution Mw / Mnde of less than 3.0; and a density of from 0.910 to 0.946 g / cm3; and (2) 90 to 30% by weight of a second ethylene copolymer having a melt index I2 of from 25 to 1500 g / 10 min; a molecular weight distribution Mw / Mnde of less than 3.0; and a density higher than the density of the first ethylene copolymer, but less than 0.970 g / cm3; wherein the density of the second ethylene copolymer is less than 0.037 g / cm3 higher than the density of the first ethylene copolymer; the ratio (SCB1 / SCB2) of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer (SCB1) to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB2) is greater than 1.0; and wherein the polyethylene copolymer composition has a molecular weight distribution Mw / Mn, from 1.8 to 7.0; a density of less than 0.949 g / cm3; a high load melt index I21, of at least 150 g / 10 min; a Z average molecular weight Mz, of less than 200,000; a melt flow ratio I21 / I2, from 20 to 50; a strain exponent of less than 1.40; and an ESCR Condition B (100% Igepal) of at least 3.5 hours; and wherein the polyethylene copolymer composition further comprises a nucleating agent. An embodiment of the disclosure is a film, the film comprising a polyethylene copolymer composition comprising: (1) 10 to 70% by weight of a first ethylene copolymer having a melt index I2 of from 0.1 to 10 q / 10 min; a molecular weight distribution Mw / Mnde of less than 3.0; and a density of from 0.910 to 0.946 g / cm3; and (2) 90 to 30% by weight of a second ethylene copolymer having a melt index I2 of from 25 to 1500 g / 10 min; a molecular weight distribution Mw / Mnde of less than 3.0; and a density higher than the density of the first ethylene copolymer, but less than 0.970 g / cm3; wherein the density of the second ethylene copolymer is less than 0.037 g / cm3 higher than the density of the first ethylene copolymer; the ratio (SCB1 / SCB2) of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer (SCB1) to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB2) is greater than 1.0; and wherein the polyethylene copolymer composition has a molecular weight distribution Mw / Mn, from 1.8 to 7.0; a density of less than 0.949 g / cm3; a high load melt index I21, of at least 150 g / 10 min; a Z average molecular weight Mz, of less than 200,000; a melt flow ratio I21 / I2, from 20 to 50; a strain exponent of less than 1.40; and an ESCR Condition B (100% Igepal) of at least 3.5 hours; and wherein the polyethylene copolymer composition further comprises a nucleating agent. Brief Description of the Figures Figure 1 shows the gel permeation chromatographs (GPC) of the polyethylene compositions (Examples 1 and 2) prepared according to the present disclosure with the use of a differential refractometer as the detector. Figure 2 shows the normalized oxygen transmission rates (OTR) of compression molded films produced from the nucleated polyethylene compositions (Examples 1* and 2*) according to the present disclosure against the density of the core polyethylene compositions (Examples 1* and 2*). Figure 2 also shows the normalized oxygen transmission rates (OTR) of compression molded films produced from comparative core polyethylene compositions (Examples 3*, 4* and 5*) against the density of the comparative core polyethylene compositions (Examples 3*, 4* and 5*). Figure 3 shows the normalized water vapor transmission rates (WVTR) of compression molded films produced from core polyethylene compositions (Examples 1* and 2*) according to the present disclosure versus the density of the core polyethylene compositions (Examples 1* and 2*). Figure 3 also shows the normalized water vapor transmission rates (WVTR) of compression molded films produced from the comparative core polyethylene compositions (Examples 3*, 4* and 5*) versus the density of the comparative core polyethylene compositions (Examples 3*, 4* and 5*). Figure 4 shows the oxygen transmission rates (OTR) of injection molded closures made from core polyethylene compositions (Examples 1* and 2*) according to the present disclosure versus the density of the core polyethylene compositions (Examples 1* and 2*). Figure 4 also shows the oxygen transmission rates (OTR) of injection molded closures made from comparative core polyethylene compositions (Examples 3*, 4*, and 5*) versus the density of the comparative core polyethylene compositions (Examples 3*, 4*, and 5*). Figure 5 shows the ESCR (condition B, at 100% IGEPAL) for polyethylene compositions (Examples 1 and 2) made according to the present disclosure versus oxygen transmission rate (OTR) of injection molded closures made from core polyethylene compositions made according to the present disclosure (Examples 1* and 2*). Figure 5 also shows the ESCR (condition B, at 100% IGEPAL) for comparative polyethylene compositions (Examples 3, 4, and 5) versus oxygen transmission rate (OTR) of injection molded closures made from comparative core polyethylene compositions (Examples 3*, 4*, and 5*). Figure 6 shows the notched Izod impact strength for nucleated polyethylene compositions (Examples 1* and 2*) made in accordance with the present disclosure versus oxygen transmission rate (OTR) of injection molded closures made from the nucleated polyethylene compositions made in accordance with the present disclosure (Examples 1* and 2*). Figure 6 also shows the notched Izod impact strength for comparative nucleated polyethylene compositions (Examples 3*, 4*, and 5*) versus oxygen transmission rate (OTR) of injection molded closures made from the comparative nucleated polyethylene compositions (Examples 3*, 4*, and 5*). Detailed Description of the Invention The terms "ethylene homopolymer" or "polyethylene homopolymer" or "ethylene homopolymer composition" mean that the polymer referred to is the product of a polymerization process in which only ethylene, as a polymerizable olefin, was deliberately added. Conversely, the terms "ethylene copolymer" or "polyethylene copolymer" or "polyethylene copolymer composition" mean that the polymer referred to is the product of a polymerization process in which ethylene and one or more alpha-olefin comonomers were deliberately added as the polymerizable olefins. The term unimodal is defined here to mean that there will be only one significant peak or maximum evident in a GPC curve. A unimodal profile includes a broad unimodal profile. Alternatively, the term unimodal suggests the presence of a single maximum in a molecular weight distribution curve generated according to the ASTM D6474-99 method. In contrast, the term bimodal means that there will be a secondary peak or shoulder evident in a GPC curve that represents a higher or lower molecular weight component (in this case, the molecular weight distribution can be said to have two maxima in a molecular weight distribution curve). Alternatively, the term bimodal suggests the presence of two maxima in a molecular weight distribution curve generated according to the ASTM D6474-99 method.The term multimodal indicates the presence of two or more maxima in a molecular weight distribution curve generated according to the ASTM D647 4-99 method. In one embodiment of the disclosure, a polymer composition comprises from 1 to 100 weight percent of a polyethylene copolymer composition as defined herein. In one embodiment of the disclosure, a polyethylene copolymer composition comprises two components, (1) a first ethylene copolymer and (2) a second ethylene copolymer that is different from the first ethylene copolymer. In one embodiment of the disclosure, a polyethylene copolymer composition comprising two components, (1) a first ethylene copolymer and (2) a second ethylene copolymer which is different from the first ethylene copolymer, further comprises a nucleating agent. The first and second ethylene copolymers, as well as the nucleating agent, are defined below. The First Ethylene Copolymer In one embodiment of the disclosure, the first ethylene copolymer comprises both polymerized ethylene and the at least one polymerized alpha-olefin comonomer, with polymerized ethylene being the major species. In one embodiment of the disclosure, the first ethylene copolymer is manufactured using a single-site polymerization catalyst. In one embodiment of the disclosure, the first ethylene copolymer is manufactured using a single-site polymerization catalyst in a solution-phase polymerization process. In one embodiment of the disclosure, the comonomer (here alpha-olefin) content in the first ethylene copolymer may be from about 0.05 to about 3.0 mol % as measured by 13C NMR, or FTIR or GPC-FTIR methods, or as calculated from a reactor model (see Examples section). The comonomer is one or more suitable alpha-olefins, including, but not limited to, 1-butene, 1-hexene, 1-octene, and the like. In one embodiment, the alpha-olefin is 1-octene. In one embodiment of the disclosure, the short chain branching in the first ethylene copolymer may be from about 0.10 to about 15 short chain branches per thousand carbon atoms (SCB1 / 1OOOCs). In further embodiments of the disclosure, the short chain branching in the first ethylene copolymer may be from 0.10 to 10, or from 0.20 to 10, or from 0.20 to 5, or from 0.20 to 30.5, or from 0.10 to 5, or from 0.10 to 3.5, or from 0.20 to 3.5, or from 0.5 to 5, or from 0.5 to 3.5, or from 1 to 10, or from 1 to 5, or from 1 to 3.5 branches per thousand carbon atoms (SCB1 / 1OOOCs). Short chain branching is the branching due to the presence of the alpha-olefin comonomer in the ethylene copolymer and will have, for example, two carbon atoms for a 1-butene comonomer, or four carbon atoms for a 1-hexene comonomer, or six carbon atoms for a 1-octene comonomer, etc.The comonomer is one or more suitable alpha-olefins, including, but not limited to, 1-butene, 1-hexene, 1-octene, and the like. In one embodiment, the alpha-olefin is 1-octene. In embodiments of the disclosure, the comonomer in the first ethylene copolymer is one or more olefins such as, but not limited to, 1-butene, 1-hexene, 1-octene, and the like. In one embodiment of the disclosure, the first ethylene copolymer is a copolymer of ethylene and 1-octene. In one embodiment of the disclosure, the comonomer content in the first ethylene copolymer is greater than the comonomer content of the second ethylene copolymer (as reported, for example, in mol %). In one embodiment of the disclosure, the amount of short chain branching in the first ethylene copolymer is greater than the amount of short chain branching in the second ethylene copolymer (as reported in short chain branches, SCB per thousand carbons in the polymer backbone, lOOOCs). In one embodiment of the disclosure, the melt index, I21 of the first ethylene copolymer is lower than the melt index, I22 of the second ethylene copolymer. In embodiments of the disclosure, the first ethylene copolymer has a melt index, I21, of <10.0 g / 10 min, or <5.0 g / 10 min, or <2.5 g / 10 min, or <1.0 g / 10 min. In another embodiment of the disclosure, the first ethylene copolymer has a melt index, I21, of 0.001 to 10.0 g / 10 min, including any narrower range within this range and any values ​​within these ranges. For example, in embodiments of the disclosure, the melt index, I21 of the first ethylene copolymer can be from 0.001 to 7.5 g / 10 min, or from 0.001 to 5.0 g / 10 min, or from 0.001 to 2.5 g / 10 min, or 0.001 to 1.0 g / 10 min, or from 0.01 to 10.0 g / 10 min, or from 0.01 to 7.5 g / 10 min, or from 0.01 to 5.0 g / 10 min, or from 0.01 to 2.5 g / 10 min, or from 0.01 to 1.0 g / 10 min, or from 0.1 to 10.0 g / 10 min, or from 0.1 to 7.5 g / 10 min, or from 0.1 to 5.0 g / 10 min, or from 0.1 to 2.5 g / 10 min, or from 0.1 to 10.0 g / 10 min. In one embodiment of the disclosure, the first ethylene copolymer has a melt flow ratio, I21 / I2 of less than 25, or less than 23, or less than 20. In one embodiment of the disclosure, the first ethylene copolymer has a weight average molecular weight, Mw, of 40,000 to 250,000 g / mol, including any narrower range within this range and any values ​​encompassed within these ranges. For example, in embodiments of the disclosure, the first ethylene copolymer has a weight average molecular weight, Mw, of 50,000 to 200,000 g / mol, or from 50,000 to 175,000 g / mol, or from 50,000 to 150,000 g / mol, or from 40,000 to 125,000 g / mol, or from 50,000 to 135,000 g / mol. In embodiments of the disclosure, the first ethylene copolymer has a molecular weight distribution, Mw / Mn of <3.0, or <3.0, or <2.7, or <2.7, or <2.5, or <2.5, or <2.3, or <2.3, or 2.1, or <2.1, or about 2. In another embodiment of the disclosure, the first ethylene copolymer has a molecular weight distribution, Mw / Mn of from 1.7 to 3.0, including any narrower range within this range and any values ​​within these ranges. For example, in embodiments of the disclosure, the first ethylene copolymer has a molecular weight distribution, Mw / Mn of from 1.8 to 2.7, or from 1.8 to 2.5, or from 1.8 to 2.3, or from 1.9 to 2.1. In one embodiment of the disclosure, the density, d1 of the first copolymer is less than the density, d2 of the second ethylene copolymer. In one embodiment of the disclosure, the first ethylene copolymer has a density, d1, of from 0.900 to 0.950 g / cm3, including any narrower range within this range and any values ​​encompassed by these ranges. 5 For example, in embodiments of the disclosure, the first ethylene copolymer has a density, d1 of from 0.900 to 0.948 g / cm3, or from 0.905 to 0.948 g / cm3, or from 0.910 to 0.948 g / cm3, or from 0.914 to 0.948 g / cm3, or from 0.916 to 0.948 g / cm3, or from 0.918 to 0.948 g / cm3, or from 0.920 to 0.948 g / cm3, or from 0.922 to 0.948 g / cm3, or from 0.924 to 0.948 g / cm3, or from 0.900 to 0.946 g / cm3, or from 0.905 to 0.946 g / cm3, or from 0.910 to 0.946 g / cm3, or from 0.912 to 0.946 g / cm3, or from 0.914 to 0.946 g / cm3, or from 0.916 to 0.946 g / cm3, or from 0.918 to 0.946 g / cm3, or from 0.920 to 0.946 g / cm3, or from 0.922 to 0.946 g / cm3, or from 0.924 to 0.946 g / cm3, or from 0.900 to 0.944 g / cm3, or from 0.905 to 0.944 g / cm3, or from 0.910 to 0.944 g / cm3, or from 0.914 to 0.944 g / cm3, or from 0.916 to 0.944 g / cm3, or from 0.918 to 0.942 g / cm3, or from 0.920 to 0.942 g / cm3, or from 0.922 to 0.942 g / cm3, or from 0.924 to 0.942 g / cm3, or from 0.914 to 0.940 g / cm3, or from 0.916 to 0.940 g / cm3, or from 0.918 to 0.940 g / cm3, or from 0.920 to 0.940 g / cm3, or from 0.922 to 0.940 g / cm3, or from 0.924 to 0.940 g / cm3, or from 0.914 to 0.938 g / cm3, or from 0.916 to 0.938 g / cm3, or from 0.918 to 0.938 g / cm3, or from 0.920 to 0.938 g / cm3, or from 0.922 to. 0.938 g / cm3, or from 0.924 to 0.938 g / cm3. In one embodiment of the disclosure, a single site catalyst that provides an ethylene copolymer having a CDBI(50) of at least 65% by weight, or at least 70%, or at least 75%, or at least 80%, or at least 85%, during solution phase polymerization in a single reactor, is used in the preparation of the first ethylene copolymer. In one embodiment of the present disclosure, the first ethylene copolymer is an ethylene copolymer which has a CDBI(50) of greater than about 60% by weight, or greater than about 65%, or greater than about 70% or greater than about 75% by weight, or greater than about 80% or greater than about 85%. In embodiments of the disclosure, the weight percent (wt%) of the first ethylene copolymer in the polyethylene copolymer composition (here, the weight percent of the first ethylene copolymer based on the total weight of the first and second ethylene copolymers) can be from about 5 wt% to about 5 wt%, including any narrower range within this range and any values ​​within these ranges. For example, in embodiments of the disclosure, the weight percent (wt%) of the first ethylene copolymer in the polyethylene copolymer composition can be from about 5 wt% to about 90 wt%, or from about 10 wt% to about 90 wt%, or from about 5 wt% to about 80 wt%, or from about 10 wt% to about 70 wt%, or from about 5 wt% to about 70 wt%.or from about 5 wt. % to about 60 wt. %, or from about 10 wt. % to about 50 wt. %, or from about 15 wt. % to about 45 wt. %, or from about 20 wt. % to about 40 wt. %, or from about 20 wt. % to about 50 wt. %, or from about 20 wt. % to about 55 wt. %, or from about 20 wt. % to about 60 wt. %, or from about 25 wt. % to about 65 wt. %, or from about 25 wt. % to about 60 wt. %, or from about 30 wt. % to about 60 wt. %, or from about 30 wt. % to about 55 wt. %, or from about 30 wt. % to about 50 wt. %, or from about 30 wt. % to about 45 wt. The second Ethylene Copolymer In one embodiment of the disclosure, the second ethylene copolymer comprises both the polymerized ethylene and the at least one polymerized alpha-olefin comonomer, with the polymerized ethylene being the majority species. In one embodiment of the disclosure, the second ethylene copolymer is manufactured using a single-site polymerization catalyst. In one embodiment of the disclosure, the second ethylene copolymer is manufactured using a single-site polymerization catalyst in a solution-phase polymerization process. In one embodiment of the disclosure, the comonomer content in the second ethylene copolymer may be from about 0.05 to about 3 mol %, as measured by 13C NMR, FTIR or GPC-FTIR methods, or as calculated from a reactor model (see Examples section). The comonomer is one or more suitable alpha-olefins, including, but not limited to, 1-butene, 1-hexene, 1-octene, and the like. In one embodiment, the alpha-olefin is 1-octene. In one embodiment of the disclosure, the short chain branching in the second ethylene copolymer may be from about 0.10 to about 10 short chain branches per thousand carbon atoms (SCB1 / 1OOOCs). In further embodiments of the disclosure, the short chain branching in the second ethylene copolymer may be from 0.10 to 7.5, or from 0.10 to 5, or from 0.10 to 3, or from 0.10 to 1.5 branches per thousand carbon atoms (SCB1 / 1OOOCs). Short chain branching is branching due to the presence of the alpha-olefin comonomer in the ethylene copolymer and will have, for example, two carbon atoms for a 1-butene comonomer, or four carbon atoms for a 1-hexene comonomer, or six carbon atoms for a 1-octene comonomer, etc. The comonomer is one or more suitable alpha-olefins. Examples of alpha-olefins include, but are not limited to, 1-butene, 1-hexene, 1-octene, and the like.In one embodiment, the alpha-olefin is 1-octene. In embodiments of the disclosure, the comonomer in the second ethylene copolymer is one or more olefins such as, but not limited to, 1-butene, 1-hexene, 1-octene, and the like. In one embodiment of the disclosure, the second ethylene copolymer is a copolymer of ethylene and 1-octene. In one embodiment of the disclosure, the comonomer content in the second ethylene copolymer is less than the comonomer content of the first ethylene copolymer (as reported, for example, in mol %). In one embodiment of the disclosure, the amount of short chain branches in the second ethylene copolymer is less than the amount of short chain branches in the first ethylene copolymer (as reported in short chain branches, SCB per thousand carbon atoms in the polymer backbone, lOOOCs). In one embodiment of the disclosure, the melt index, I22 of the second ethylene copolymer is greater than the melt index, I21 of the first ethylene copolymer. In one embodiment of the disclosure, the ratio of the melt index, I22 of the second ethylene copolymer to the melt index, I21 of the first ethylene copolymer is from 1.1 to 1000, including any narrower range within this range and any values ​​encompassed by these ranges. For example, in embodiments of the disclosure, the ratio of the melt index, I22 of the second ethylene copolymer to the melt index, I21 of the first ethylene copolymer may be from 1.1 to 7.50, or from 1.1 to 500. In embodiments of the disclosure, the second ethylene copolymer has a melt index, I22, of from 10 to 5,000, including any narrower range within this range and any value encompassed by these ranges. For example, in embodiments of the disclosure, the melt index, I22 of the second ethylene copolymer is from 10 to 2500 g / 10 min, or from 15 to 2500 g / 10 min, or from 25 to 5000 g / 10 min, or from 10 to 1,500 g / 10 min, or from 15 to 1,500 g / 10 min, or from 25 to 1500 g / 10 min, or from 10 to 1000 g / 10 min, or from 15 to 1000 g / 10 min, or from 25 to 1000 g / 10 min, or from 50 to 5,000 g / 10 min, or from 50 to 2500 g / 10 min, or from 50 to 1500 g / 10 min, or from 50 to 1000 g / 10 min, or from 50 to 500 g / 10 min, or from 10 to 500 g / 10 min, or 15 to 500 g / 10 min, or from 25 to 500 g / 10 min, or from 10 to 250 g / 10 min, or from 25 to 250 g / 10 min, or from 50 to 250 g / 10 min. In one embodiment of the disclosure, the second ethylene copolymer has a melt flow ratio, I21 / I2 of less than 25, or less than 23, or less than 20. In one embodiment of the disclosure, the second ethylene copolymer has a weight average molecular weight, Mw of <75,000 g / mol, or 60,000 g / mol, or <50,000 g / mol, or 45,000 g / mol, or <40,000 g / mol, or <35,000 g / mol, or 30,000 g / mol. In another embodiment, the second ethylene copolymer has a weight average molecular weight, Mw of from 5,000 to 100,000 g / mol, including any narrower range within this range and any values ​​within these ranges. For example, in embodiments of the disclosure, the second ethylene copolymer has a weight average molecular weight Mw of from 10,000 to 75,000 g / mol, or from 15,000 to 65,000 g / mol, or from 20,000 to 60,000 g / mol, or from 20,000 to 55,000 g / mol, or from 20,000 to 50,000 g / mol, or from 20,000 to 40,000 g / mol. In embodiments of the disclosure, the second ethylene copolymer has a molecular weight distribution, MK / Mnde < 3.0, or < 3.0, or < 2.7, or < 2.7, or 2.5, or < 2.5, or < 2.3, or < 2.3, or 2.1, or < 2.1, or about 2. In another embodiment of the disclosure, the second ethylene copolymer has a molecular weight distribution, Mw / Mnde of 1.7 to 3.0, including any narrower range within this range and any values ​​within these ranges. For example, in embodiments of the disclosure, the second ethylene copolymer has a molecular weight distribution, Mw / Mnde of 1.8 to 2.7, or from 1.8 to 2.5, or from 1.8 to 2.3, or from 1.9 to 2.1. In one embodiment of the disclosure, the density, d2 of the second copolymer is greater than the density, d1 of the first ethylene copolymer. In one embodiment of the disclosure, the density, d2 of the second ethylene copolymer is less than 0.037 g / cm3 greater than the density, d1 of the first ethylene copolymer. In one embodiment of the disclosure, the density, d2 of the second ethylene copolymer is less than 0.035 g / cm3 greater than the density, d1 of the first ethylene copolymer. In one embodiment of the disclosure, the density, d2 of the second ethylene copolymer is less than 0.031 g / cm3 greater than the density, d1 of the first ethylene copolymer. In one embodiment of the disclosure, the density, d2 of the second ethylene copolymer is less than 0.030 g / cm3 greater than the density, d1 of the first ethylene copolymer. In one embodiment of the disclosure, the density, d2 of the second ethylene copolymer is less than 0.02 5 g / cm3 greater than the density, d1 of the first ethylene copolymer. In one embodiment of the disclosure, the second ethylene copolymer has a density, d2, of less than 0.970 g / cm3, or less than 0.967 g / cm3, or less than 0.965 g / cm3, or less than 0.963 g / cm3, or less than 0.961 g / cm3. In one embodiment of the disclosure, the second ethylene copolymer has a density, d2, of from 0.943 to 0.985 g / cm3, including any narrower range within this range and any values ​​within these ranges. For example, in embodiments of the disclosure, the second ethylene copolymer has a density, d2, of from 0.945 to 0.985 g / cm3, or 10 from 0.947 to 0.985 g / cm3, or from 0.950 to 0.985 g / cm3, or from 0.943 to 0.980 g / cm3, or from 0.945 to 0.980 g / cm3, or from 0.947 to 0.980 g / cm3, or from 0.950 to 0.980 g / cm3, or from 0.951 to 0.985 g / cm3, or from 0.951 to 0.985 g / cm3, or from 0.951 to 0.980 g / cm3, or from 0.943 to 0.975 g / cm3, or 15 from 0.945 to 0.975 g / cm3, or from 0.947 to 0.975 g / cm3, or from 0.950 to 0.975 g / cm3, or from 0.950 to 0.970 g / cm3, or from 0.945 0.946 to 0 0.965 g / cm3, .963 g / cm3, or from 0.947 from 0.948 to 0.965 963 g / cm3 g / cm3, or In one embodiment of the disclosure, a single site catalyst that provides an ethylene copolymer having a CDBI(50) of at least 65% by weight, or at least 70%, or at least 75%, or at least 80%, or at least 85%, during solution phase polymerization in a single reactor, is used in the preparation of the second ethylene copolymer. In one embodiment of the present disclosure, the second ethylene copolymer is an ethylene copolymer having a CDBI(50) of greater than about 60% by weight, or greater than about 65%, or greater than about 70%, or greater than about 75% by weight, or greater than about 80%, or greater than about 85%. In embodiments of the disclosure, the weight percent (wt%) of the second ethylene copolymer in the polyethylene copolymer composition (here, the weight percent of the second ethylene copolymer based on the total weight of the first and second ethylene copolymers) may be from about 95 wt% to about 5 wt%, including any narrower range within this range and any values ​​within these ranges. For example, in embodiments of the disclosure, the weight percent (wt%) of the second ethylene copolymer in the polyethylene copolymer composition may be from about 90 wt% to about 10 wt%, or from about 90 wt% to about 20 wt%., or from about 90% by weight to about 30% by weight, or from about 90% by weight to about 40% by weight, or from about 90% by weight to about 50% by weight, or from about 80% by weight to about 50% by weight, or from about 80% by weight to about 45% by weight, or from about 80% by weight to about 60% by weight, or from about 70% by weight to about 45% by weight, or from about 75% by weight to about 50% by weight, or from about 70% by weight to about 55% by weight. The composition of Polyethylene Copolymer In one embodiment of the disclosure, the polyethylene copolymer composition will comprise a first ethylene copolymer and a second ethylene copolymer (each as defined herein). In one embodiment of the disclosure, the polyethylene copolymer composition has a bimodal profile (in this case, a bimodal molecular weight distribution) in a gel permeation chromatography (GPC) analysis. In one embodiment of the disclosure, the polyethylene copolymer composition has a unimodal profile (in this case, a unimodal molecular weight distribution) in a gel permeation chromatography (GPC) analysis. In one embodiment of the disclosure, the polyethylene copolymer composition has a bimodal profile on a gel permeation chromatograph generated according to the ASTM D6474-99 method. In one embodiment of the disclosure, the polyethylene copolymer composition has a unimodal profile on a gel permeation chromatograph generated according to the ASTM D6474-99 method. In one embodiment of the disclosure, the polyethylene copolymer composition comprising a first ethylene copolymer and a second ethylene copolymer (as defined above) will have a ratio (SCB1 / SCB2) of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer (herein, SCB1) to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (herein, SCB2) of greater than 1.0 (herein, SCB1 / SCB2>1.0). In further embodiments of the disclosure, the ratio of the short chain branches in the first ethylene copolymer (SCB1) to the short chain branches in the second ethylene copolymer (SCB2) is at least 1.5 or greater than 1.5.In still further embodiments of the disclosure, the ratio of short chain branches in the first ethylene copolymer (SCB1) to the short chain branches in the second ethylene copolymer (SCB2) is at least 2.0 or greater than 2.0. In yet another embodiment of the disclosure, the ratio of short chain branches in the first ethylene copolymer (SCB1) to the short chain branches in the second ethylene copolymer (SCB2) is at least 2.5. In embodiments of the disclosure, the ratio (SCB1 / SCB2) of the short chain branching in the first ethylene copolymer (SCB1) to the short chain branching in the second ethylene copolymer (SCB2) will be from greater than 1.0 to about 12.0, or from greater than 1.0 to about 10, or from greater than 1.0 to about 7.0, or from greater than 1.0 to about 5.0, or from about 1.5 to about 10, or from about 1.5 to about 7.0, or from about 1.5 to about 5.0. In one embodiment of the disclosure, the polyethylene copolymer composition has a weight average molecular weight, Mw of <100,000 g / mol, or <75,000 g / mol, or <70,000 g / mol, or <65,000 g / mol, or <65,000 g / mol, or <60,000 g / mol, or <60,000 g / mol. In another embodiment, the polyethylene copolymer composition has a weight average molecular weight, Mw of from 20,000 to 125,000 g / mol, including any narrower range within this range and any values ​​encompassed by these ranges. For example, in embodiments of the disclosure, the polyethylene copolymer composition has a weight average molecular weight, MK, of from 25,000 to 100,000 g / mol, or from 25,000 to 90,000 g / mol, or from 30,000 to 80,000 g / mol, or from 30,000 to 75,000 g / mol. In one embodiment of the disclosure, the polyethylene copolymer composition has a number average molecular weight, M of <60,000 g / mol, or <50,000 g / mol, or <50,000 g / mol, or <45,000 g / mol, or <45,000 g / mol, or <40,000 g / mol, or <40,000 g / mol, or <35,000 g / mol, or <35,000 g / mol, or <30,000 g / mol, or <30,000 g / mol. In another embodiment of the disclosure, the polyethylene copolymer composition has a number average molecular weight, M of from 5,000 to 60,000 g / mol, including any narrower range within this range and any values ​​encompassed by these ranges. For example, in embodiments of the disclosure, the polyethylene copolymer composition has a number average molecular weight, Mn, of from 10,000 to 55,000 g / mol, or from 10,000 to 50,000 g / mol, or from 15,000 to 50,000 g / mol, or from 15,000 to 45,000 g / mol, or from 15,000 to 40,000 g / mol, or from 15,000 to 35,000 g / mol, or from 15,000 to 30,000 g / mol, or from 15,000 to 25,000 g / mol. In one embodiment of the disclosure, the polyethylene copolymer composition has a Z average molecular weight, Mz, below about 200,000 g / mol. In another embodiment of the disclosure, the polyethylene copolymer composition has a Z average molecular weight, Mz, below about 175,000 g / mol. In another embodiment of the disclosure, the polyethylene copolymer composition has a Z average molecular weight, Mz, below about 150,000 g / mol. In yet another embodiment of the disclosure, the polyethylene copolymer composition has a Z average molecular weight, Mz, below about 125,000 g / mol. In embodiments of the disclosure, the polyethylene copolymer composition has a molecular weight distribution, Mw / Mn of <7.0, or <7.0, or <6.5, or <6.5, or <6.0, or <6.0, or 5.5, or <5.5, or <5.0, or <5.0, or <4.5, or <4.5, or <4.0, or <4.0, or <3.5, or <3.5, or <3.0, or <3.0. In another embodiment of the disclosure, the polyethylene copolymer composition has a molecular weight distribution, Mw / Mn of from 1.7 to 7.0, including any narrower range within this range and any values ​​within these ranges. For example, in embodiments of the disclosure, the polyethylene copolymer composition has a molecular weight distribution, Mw / Mn, of from 1.8 to 7.0, or from 1.8 to 6.5, or from 1.8 to 6.0, or from 1.8 to 5.5, or from 1.8 to 5.0, or from 1.8 to 4.5, or from 1.8 to 4.0, or from 1.8 to 3.5, or from 1.8 to 3.0, or from 1.8 to 2.5, or from 2.0 to 5.0, or from 2.0 to 4.5, or from 2.0 to 4.0, or from 2.0 to 3.5, or from 2.0 to 3.0. In embodiments of the disclosure, the polyethylene copolymer composition has a density of <0.950 g / cm3, or <0.950 g / cm3, or <0.94 9 g / cm3, or <0.94 9 g / cm3, or <0.94 8 g / cm3, or <0.94 8 g / cm3. In one embodiment of the disclosure, the polyethylene copolymer composition has a density from 0.932 to 0.950 g / cm3, including any narrower range within this range and any values ​​encompassed by these ranges. For example, in embodiments of the disclosure, the polyethylene copolymer composition has a density of from 0.934 to 0.950 g / cm 3 , or from 0.934 to 0.949 g / cm 3 , or from 0.934 to less than 0.949 g / cm 3 , or from 0.934 to 0.948 g / cm 3 , or from 0.936 to 0.950 g / cm 3 , or from 0.936 to 0.949 g / cm 3 , or from 0.936 to less than 0.949 g / cm 3 , or from 0.936 to 0.948 g / cm 3 , or from 0.938 to 0.950 g / cm 3 , or from 0.938 to 0.949 g / cm 3 , or from 0.938 to less than 0.949 g / cm3, or from 0.938 to 0.948 g / cm3, or from 0.939 to 0.950 g / cm3, or from 0.939 to 0.949 g / cm3, or from 0.939 to less than 0.949 g / cm3, or from 0.939 to 0.948 g / cm3, or from 0.940 to 0.950 g / cm3, or from 0.940 to 0.949 g / cm3, or from 0.940 to less than 0.949 g / cm3, or from 0.940 to 0.948 g / cm3, or from 0.941 to 0.950 g / cm3, or from 0.941 to 0.949 g / cm3, or from 0.941 to less than 0.949 g / cm3, or from 0.941 to 0.948 g / cm3. In embodiments of the disclosure, the polyethylene copolymer composition has a melt index, I2 of at least 1.0 g / 10 min (h 1.0 g / 10 min), or at least 3.0 g / 10 min (>3.0 g / 10 min), or at least 5.0 g / 10 min (>5.0 g / 10 min), or at least 7.5 g / 10 min (>7.5 g / 10 min), or at least 10 g / 10 min (>10.0 g / 10 min), or greater than 3.0 g / 10 min (>3.0 g / 10 min), or greater than 5.0 g / 10 min (>5.0 g / 10 min), or greater than 7.5 g / 10 min (>7.5 g / 10 min), or greater than 10.0 g / 10 min (>10.0 g / 10 min). In another embodiment of the disclosure, the polyethylene copolymer composition has a melt index, I2 of 1.0 to 100 g / 10 min, including any narrower range within this range and any values ​​within these ranges. For example, in embodiments of the disclosure, the melt index, I2 of the polyethylene copolymer composition may be from 1.0 to 75 g / 10 min, or from 1.0 to 50 g / 10 min, or from 1 to 25 g / 10 min, or from 3.0 to 100 g / 10 min, or from 3.0 to 75 g / 10 min, or from 3.0 to 50 g / 10 min, or from 3.0 to 25 g / 10 min, or from 3.0 to 20.0 g / 10 min, or from more than 3.0 to less than 20.0 g / 10, or from 5.0 to 100 g / 10 min, or from 5.0 to 75 g / 10 min, or from 50.0 to 50 g / 10 min, or from 50.0 to 25 g / 10 min, or from 5.0 to 20.0 g / 10 min, or from more than 5.0 to less than 20.0 g / 10 min, or from more than 10.0 to less than 25.0 g / 10 min, or from more than 10.0 to less than 20.0 g / 10 min. In embodiments of the disclosure, the polyethylene copolymer composition has a high fill melt index, I21 of at least 150 g / 10 min (>150 g / 10 min), or at least 175 g / 10 min (h 175 g / 10 min), or at least 200 g / 10 min (>200 g / 10 min), or greater than 200 g / 10 min (>200 g / 10 min), or at least 225 g / 10 min (>225 g / 10 min), or greater than 225 g / 10 min (>225 g / 10 min), or at least 250 g / 10 min (>250 g / 10 min), or greater than 250 g / 10 min (>250 g / 10 min). In another embodiment of the disclosure, the polyethylene copolymer composition has a high load melt index, I21 of from 175 to 1200 g / 10 min, including any narrower range within this range and any values ​​within these ranges.For example, in embodiments of the disclosure, the high load melt index, I21 of the polyethylene copolymer composition may be from 175 to 1000 g / 10 min, or from 175 to 750 g / 10 min, from 200 to 1000 g / 10 min, or from 200 to 750 g / 10 min, or from 225 to 1000 g / 10 min, or from 225 to 750 g / 10 min, or from 250 to 1000 g / 10 min, or from 250 to 750 g / 10 min, or from 200 to 500 g / 10 min. In embodiments of the disclosure, the polyethylene copolymer composition has a melt flow ratio, I21 / I2 of <60, or <60, or <50, or <50, or <45, or <40, or <35, or <35, or <30, or <30. In another embodiment of the disclosure, the polyethylene copolymer composition has a melt flow ratio, I21 / I2 of from 15 to 60, including any narrower range within this range and any values ​​encompassed by these ranges. For example, in embodiments of the disclosure, the polyethylene copolymer composition has a melt flow ratio, I21 / I2 of from 16 to 50, or from 16 to 42, or from 18 to 50, or from 20 to 50, or from 22 to 50, or from 18 to 45, or from 18 to 40, or from 16 to 40, or from 16 to 38, or from 18 to 34, or from 18 to 32, or from 20 to 30. In one embodiment of the disclosure, the polyethylene copolymer composition has a strain exponent, defined as Logio[Ie / l2] / Logio[6.48 / 2.16], which is d 1.40. In further embodiments of the disclosure, the polyethylene copolymer composition has a strain exponent, Logio [Ie / l2] / Logio [ 6.48 / 2.16] of less than 1.38, or less than 1.36, or less than 1.34, or less than 1.32, or less than 1.30. In one embodiment of the disclosure, the polyethylene copolymer composition has a shear viscosity at about 10^3-1(240°C) of less than about 10 Pa.s. In one embodiment of the disclosure, the polyethylene copolymer composition has a shear viscosity at about 105s-1(240°C) of from about 2 to about 10 Pa.s including any narrower range within this range and any values ​​within these ranges. For example, in embodiments of the disclosure, the polyethylene copolymer composition has a shear viscosity at about 10^^-1(240°C) of from about 3 to about 9 Pa.s, or from about 4 to about 9 Pa.s, or from about 4 to about 8.5 Pa.s. In one embodiment of the invention, the shear viscosity ratio, SVR (100,100000) at 240° C. of the polyethylene copolymer composition may be from about 10 to about 80, inclusive of any narrower range within this range and any values ​​within these ranges. For example, in embodiments of the disclosure, the shear viscosity ratio, SVR (100,100000) at 240° C. of the polyethylene copolymer composition may be from about 20 to about 80, 0 from about 25 to about 75, 0 from about 30 to about 70, or from about 35 to about 75, 0 from about 30 to about 65, or from about 30 to about 55, 0 from 35 to 65, 0 from 35 to 60. In one embodiment of the invention, the polyethylene copolymer composition or a molded article made from the polyethylene composition has a notched Izod impact strength of at least 0.04354 mkg / cm (0.80 ft.lb / in.), or at least 0.04627 m"kg / cm (0.85 ft.lb / in.), or at least 0.04899 m"kg / cm (0.90 ft.lb / in.), or at least 0.05062 m"kg / cm (0.93 ft.lb / in., as measured in accordance with ASTM D256. In one embodiment of the disclosure, the polyethylene copolymer composition has a hexane extractables value of <5.5 weight percent, or less than 4.5 weight percent, or less than 3.5 weight percent, or less than 2.5 weight percent, or less than 2.0 weight percent, or less than 1.5 weight percent, or less than 1.0 weight percent, or less than 0.5 weight percent. In one embodiment of the disclosure, the polyethylene copolymer composition has a composition distribution breadth index (CDBI(50)), as determined by temperature elution fractionation (TREF), of > about 60 weight percent. In further embodiments of the disclosure, the polyethylene composition will have a CDBI(50) of greater than about 65%, or greater than about 70%, or greater than about 75%, or greater than about 80%, or greater than about 85%. In one embodiment of the disclosure, the polyethylene copolymer composition has a composition distribution breadth index (CDBI (25)), as determined by temperature elution fractionation (TREF), of > about 55 weight percent. In further embodiments of the disclosure, the polyethylene composition will have a CDBI (25) of greater than about 60%, or greater than about 65%, or from about 55 to about 75%, or from about 60 to about 75%. In one embodiment of the disclosure, the polyethylene copolymer composition, or a molded article (or slab) made from the polyethylene copolymer composition, has a 100% Condition B environmental stress crack resistance ESCR of at least about 3.0 hours as measured in accordance with ASTM D1693 (at 50°C using 100% IGEPAL, Condition B). In one embodiment of the disclosure, the polyethylene copolymer composition, or a molded article (or slab) made from the polyethylene copolymer composition, has a 100% Condition B environmental stress crack resistance ESCR of at least about 3.5 hours as measured in accordance with ASTM D1693 (at 50°C using 100% IGEPAL, Condition B).In one embodiment of the disclosure, the polyethylene copolymer composition, or a molded article (or slab) made from the polyethylene copolymer composition, has a 100% Condition B environmental stress crack resistance ESCR of at least about 4.0 hours as measured in accordance with ASTM D1693 (at 50° C. using 100% IGEPAL, Condition B). In one embodiment of the disclosure, the polyethylene copolymer composition, or a molded article (or slab) made from the polyethylene copolymer composition, has a 100% Condition B environmental stress crack resistance ESCR of at least about 4.5 hours as measured in accordance with ASTM D1693 (at 50° C. using 100% IGEPAL, Condition B).In one embodiment of the disclosure, the polyethylene copolymer composition or a molded article (or slab) made from the polyethylene copolymer composition has a 100% Condition B Environmental Stress Crack Resistance ESCR of at least about 5.0 hours, as measured in accordance with ASTM. D1693 (at 50°C with the use of 100% IGEPAL, condition B). In one embodiment of the disclosure, the polyethylene copolymer composition, or a molded article (or slab) made from the polyethylene copolymer composition, has a 100% Condition B environmental stress crack resistance ESCR of from about 3.5 to about 15 hours, as measured in accordance with ASTM D1693 (at 50° C. using 100% IGEPAL, Condition B) including any narrower range within this range and any values ​​encompassed by these ranges. For example, in embodiments of the disclosure, the polyethylene copolymer composition, or a molded article (or slab) made from the polyethylene copolymer composition, has a 100% Condition B environmental stress crack resistance ESCR of from about 3.5 to about 12 hours, as measured in accordance with ASTM D1693 (at 50° C. using about 100% IGEPAL, Condition B), or of about 3.5 to about 10 hours, measured in accordance with ASTM D1693 (at 50°C with the use of about 100% IGEPAL, condition B), or from about 4.0 to about 15 hours, measured in accordance with ASTM D1693 (at 50°C with the use of 100% IGEPAL, condition B), or from about 4.5 to about 12 hours, measured in accordance with ASTM D1693 (at 50°C with the use of 100% IGEPAL, condition B), or from about 5 to about 10 hours, as measured in accordance with ASTM D1693 (at 50°C with the use of 100% IGEPAL, condition B). The polyethylene copolymer composition of this disclosure may be prepared using any conventional blending method such as, but not limited to, physical blending and in situ blending by polymerization in multiple reactor systems. For example, blending of the first ethylene copolymer with the second ethylene copolymer may be accomplished by melt blending the two preformed polymers. Processes in which the first and second ethylene copolymers are prepared in at least two sequential polymerization steps are preferred; however, the use of a dual reactor process in either series or parallel is contemplated herein. Gas phase, slurry phase, or solution phase reactor systems may be employed; solution phase reactor systems are preferred. Mixed catalyst single reactor systems can also be employed to prepare the polyethylene copolymer compositions of the present disclosure. In one embodiment of the current disclosure, a dual reactor solution polymerization process is used as described in, for example, U.S. Patent No. 6,372,864 and U.S. Patent Application Ser. 20060247373A1 which are incorporated herein by reference Generally, the catalysts used in the present disclosure will be so-called single-site catalysts based on a Group 4 metal having at least one cyclopentadienyl ligand. Examples of such catalysts which include metallocenes, constrained geometry catalysts and phosphinimine catalysts are typically used in combination with activators selected from the methylaluminoxanes, boranes or ionic borate salts and are further described in U.S. Pat. Nos. 3, 45,992; 5,324,800; 5,064,802; 5,055,438; 6,689,847; 6,114,481 and 6,063,879. Such single-site catalysts are distinguished from the traditional Ziegler-Natta or Phillips catalysts which are also well known in the prior art. In general, single-site catalysts produce ethylene copolymers having a molecular weight distribution (Mw / Mn) of less than about 3.0, or in some cases less than about 2.5. In embodiments of the disclosure, a single site catalyst, which provides an ethylene copolymer having a molecular weight distribution (Mw / Mn) of less than about 3.0, or less than about 2.7, or less than about 2.5, is used in the preparation of each of the first and second ethylene copolymers. In one embodiment of the disclosure, the first and second ethylene copolymers are prepared using an organometallic complex of a Group 3, 4, or 5 metal further characterized by having a phosphinimine ligand. Such a complex, when active for olefin polymerization, is generally referred to as a phosphinimine catalyst (polymerization). Non-limiting examples of phosphinimine catalysts can be found in U.S. Pat. Nos. 6,342,463; 6,235,672; 6,372,864; 6,984,695; 6,063,879; 6,777,509 and 6,277,931, all of which are incorporated herein by reference. Some non-limiting examples of metallocene catalysts can be found in U.S. Patent Nos. 4,808,561; 4,701,432; 4,937,301; 5,324,800; 5,633,394; 4,935,397; 6,002,033 and 6,489,413, which are incorporated herein by reference. Some non-limiting examples of constrained geometry catalysts can be found in U.S. Patent Nos. 5,057,475; 5,096,867; 5,064,802; 5,132,380; 5,703,187 and 6,034,021, all of which are incorporated herein by reference in their entireties. In one embodiment of the disclosure, the use of a single-site catalyst that does not produce long-chain branches (LCB) is preferred. Hexyl (C6) branches detected by NMR are excluded from the definition of long-chain branching in the present disclosure. In embodiments of the disclosure, the polyethylene copolymer composition has no long chain branches or has undetectable levels of long chain branches. Without wishing to be bound by any theory, long chain branching can increase viscosity at low shear rates, thereby negatively impacting cycle times during cap and closure manufacturing, such as during the compression molding process. Long chain branching can be determined using 13C NMR methods and can be quantitatively evaluated using the method described by Randall in Rev. Macromol. Chem. Phys. C29 (2 and 3), p. 285. In one embodiment of the disclosure, the polyethylene copolymer composition will contain less than 0.3 long chain branches per 1000 carbon atoms. In another embodiment of the disclosure, the polyethylene copolymer composition will contain less than 0.01 long chain branches per 1000 carbon atoms. In one embodiment of the disclosure, the polyethylene copolymer composition is prepared by contacting ethylene and at least one alpha-olefin with a polymerization catalyst under solution phase polymerization conditions in at least two polymerization reactors (for an example of solution phase polymerization conditions, see e.g., U.S. Patent Nos. 6,372,864 and 6,984,695 and U.S. Patent Application 20060247373A1). In one embodiment of the disclosure, the polyethylene copolymer composition is prepared by contacting at least one single-site polymerization catalyst system (comprising at least one single-site catalyst and at least one activator) with ethylene and at least one comonomer (e.g., a C3-C8 alpha-olefin) under solution polymerization conditions in at least two polymerization reactors. In one embodiment of the disclosure, a Group 4 single-site catalyst system, comprising a single-site catalyst and an activator, is used in a solution-phase dual reactor system to prepare a polyethylene copolymer composition by polymerizing ethylene in the presence of an alpha-olefin comonomer. In one embodiment of the disclosure, a group 4 single-site catalyst system, comprising a single-site catalyst and an activator, is used in a solution-phase dual reactor system to prepare a polyethylene copolymer composition by polymerizing ethylene in the presence of 1-octene. In one embodiment of the disclosure, a Group 4 phosphinimine catalyst system, comprising a phosphinimine catalyst and an activator, is used in a solution phase dual reactor system to prepare a polyethylene copolymer composition by polymerizing ethylene in the presence of an alpha-olefin comonomer. In one embodiment of the disclosure, a Group 4 phosphinimine catalyst system, comprising a phosphinimine catalyst and an activator, is used in a solution phase dual reactor system to prepare a polyethylene copolymer composition by polymerizing ethylene in the presence of 1-octene. In one embodiment of the disclosure, a dual solution phase reactor system comprises two solution phase reactors connected in series. In one embodiment of the disclosure, a polymerization process for preparing the polyethylene copolymer composition comprises contacting at least one single-site polymerization catalyst system (comprising at least one single-site catalyst and at least one activator) with ethylene and at least one alpha-olefin comonomer under solution polymerization conditions in at least two polymerization reactors. In one embodiment of the disclosure, a polymerization process for preparing the polyethylene copolymer composition comprises contacting at least one single-site polymerization catalyst system with ethylene and at least one alpha-olefin comonomer under solution polymerization conditions in a first reactor and a second reactor configured in series. In one embodiment of the disclosure, a polymerization process for preparing the polyethylene copolymer composition comprises contacting at least one single-site polymerization catalyst system with ethylene and at least one alpha-olefin comonomer under solution polymerization conditions in a first reactor and a second reactor configured in series, with the at least one alpha-olefin comonomer being fed exclusively to the first reactor. The production of the polyethylene copolymer composition of the present disclosure will typically include an extrusion or compounding step. These steps are well known in the prior art. The polyethylene copolymer composition may comprise polymer components additional to the first and second ethylene copolymers. Such polymer components include polymers prepared in situ or polymers added to the polymer composition during an extrusion or compounding step. Optionally, additives can be added to the polyethylene copolymer composition. Additives can be added to the polyethylene copolymer composition during an extrusion or compounding step, but other suitable known methods will be apparent to one skilled in the art. The additives can be added as is or as part of a separate polymer component (in this case, not the first or second ethylene copolymers described herein), or they can be added as part of a masterbatch (optionally during an extrusion or compounding step).Suitable additives are known in the prior art and include, but are not limited to, antioxidants, phosphites and phosphonites, nitrones, antacids, UV light stabilizers, UV absorbers, metal deactivators, dyes, fillers and reinforcing agents, nanoscale organic or inorganic materials, antistatic agents, lubricating agents such as calcium stearates, slip additives such as erucamide or behenamide, and nucleating agents (including nucleators, pigments, or any other chemicals which can provide a nucleating effect to the polyethylene copolymer composition). Additives that may be optionally added are typically added in an amount of up to 20 weight percent (wt %). One or more nucleating agents may be introduced into the polyethylene copolymer composition by kneading a mixture of the polymer, usually in powder or granule form, with the nucleating agent, which may be used alone or in the form of a concentrate containing further additives such as stabilizers, pigments, antistatic agents, UV stabilizers and fillers. It should be a material which is wetted or absorbed by the polymer, which is insoluble in the polymer and of a higher melting point than that of the polymer, and should be homogeneously dispersible in the molten polymer in as fine a form as possible (1 to 10 µm).Compounds known to have nucleating capacity for polyolefins include salts of monobasic or dibasic aliphatic acids or arylalkyl acids, such as sodium succinate or aluminum phenylacetate; and alkali metal or aluminum salts of aromatic or alicyclic carboxylic acids, such as sodium β-naphthoate or sodium benzoate. Some non-limiting examples of commercially available nucleating agents that may be added to the polyethylene copolymer composition are dibenzylidene sorbital esters (such as the products sold under the trademark MILLAD® 3988 by Milliken Chemical and IRGACLEAR® by Giba Specialty Chemicals). Other non-limiting examples of nucleating agents that may be added to the polyethylene copolymer composition include the cyclic organic structures described in U.S. Patent No. 5,981,636 (and salts thereof, such as disodium bieldo[2.2.1] heptene dicarboxylate); the saturated versions of the structures described in U.S. Patent No. 5,981,636 (as described in U.S. Patent No. 6,465,551; Zhao et al., De Milliken); the salts of certain cyclic dicarboxylic acids having a hexahydrophthalic acid structure (or HHPA structure) as described in U.S. Patent No. 6,599,971 (Dotson et al., De Milliken); and phosphate esters, such as those described in U.S. Patent No. 5,342,868 and sold under the trade names NA-11 and NA-21 by Asahi Denka Kogyo, the cyclic dicarboxylates and their salts, such as the divalent metal or metalloid salts (particularly the calcium salts) of the HHPA structures described in U.S. Patent No. 6,599,971. For clarity, the HHPA structure generally comprises a ring structure with six carbon atoms in the ring and two carboxylic acid groups which are substituents on adjacent atoms of the ring structure. The other four carbon atoms of the ring may be substituted, as described in U.S. Patent No. 6,599,971.An example is 1,2-cyclohexanedicarboxylic acid, calcium salt (CAS Registry Number 491589-22-1). Still further non-limiting examples of nucleating agents that can be added to the polyethylene copolymer composition include those described in WO2015042561, WO2015042563, WO2015042562 and WO2011050042. Many of the nucleating agents described above can be difficult to mix with the polyethylene copolymer composition being nucleated and it is known to use dispersion aids, such as zinc stearate, to mitigate this problem. In one embodiment of the disclosure, the nucleating agents are sufficiently dispersed in the polyethylene copolymer composition. In one embodiment of the disclosure, the amount of nucleating agent used is comparatively small, from 100 to 4000 parts per million by weight (based on the weight of the polyethylene copolymer composition) so that those skilled in the art will appreciate that some care must be taken to ensure that the nucleating agent is sufficiently dispersed. In one embodiment of the disclosure, the nucleating agent is added in finely divided form (less than 50 microns, especially less than 10 microns) to the polyethylene copolymer composition to facilitate mixing.This type of physical blending (in this case, a mixture of the nucleating agent and the resin in solid form), is in one preferred embodiment, the use of a nucleator masterbatch (where the term masterbatch refers to the practice of first melt-blending the additive—the nucleator, in this case—with a small amount of the polyethylene copolymer composition—then melt-blending the masterbatch with the remaining mass of the polyethylene copolymer composition). In one embodiment of the disclosure, an additive such as a nucleating agent may be added to the polyethylene copolymer composition by means of masterbatch, where the term masterbatch refers to the practice of first melt blending the additive (e.g., a nucleator) with a small amount of the polyethylene copolymer composition, followed by melt blending the masterbatch with the remaining mass of the polyethylene copolymer composition. In one embodiment of the disclosure, the polyethylene copolymer composition further comprises a nucleating agent. In one embodiment of the disclosure, the polyethylene copolymer composition comprises from 20 to 4000 ppm (in this case, parts per million, based on the total weight of the first and second ethylene copolymers in the polyethylene copolymer composition) of a nucleating agent. In one embodiment of the disclosure, the polyethylene copolymer composition further comprises a nucleating agent which is a salt of a dicarboxylic acid compound. A dicarboxylic acid compound is defined herein as an organic compound containing two carboxyl functional groups (-COOH). A salt of a dicarboxylic acid compound will then comprise one or more suitable cationic countercations, preferably metal cations, and an organic compound having two anionic carboxylate groups (-COCr). In one embodiment of the disclosure, the polyethylene copolymer composition is used in the formation of molded articles. Such articles may be formed by compression molding, continuous compression molding, injection molding, or blow molding. Such articles include, for example, caps, screw-on lids, and closures, including hinged and joined versions thereof, for bottles, containers, bags, pill bottles, assemblies, pharmaceutical bottles, and the like. In one embodiment of the disclosure, the polyethylene copolymer composition is used in forming an assembly for bottles, bags or the like. In one embodiment of the disclosure, the polyethylene copolymer composition is used in flexible packaging. In one embodiment of the disclosure, the polyethylene copolymer composition is used in the formation of films, such as, for example, blown films, cast films, and lamination or extrusion films or extrusion coating; as well as stretch films. Processes for manufacturing such films from a polymer are well known to those skilled in the art. In one embodiment of the disclosure, the polyethylene copolymer composition is used in an extrusion coating film layer. In one embodiment of the disclosure, the polyethylene copolymer composition is used in the formation of one or more film layers which are part of a multilayer film or film structure. Processes for manufacturing such films or multilayer film structures are well known to those skilled in the art. In one embodiment of the disclosure, the polyethylene copolymer composition is used in the formation of any closure, of any design and dimensions suitable for use in any hot-fill process (or aseptic filling process) for filling any suitable bottle, container or the like. In one embodiment of the disclosure, the polyethylene copolymer composition is used to form a closure for bottles, containers, bags, and the like. For example, bottle closures formed by continuous compression molding or injection molding are contemplated. Such closures include, for example, caps, hinged caps, screw-on caps, hinged screw-on caps, snap-on caps, hinged snap-on caps, and, optionally, hinged closures for bottles, containers, bags, and the like. In one embodiment of the disclosure, the polyethylene copolymer composition is employed in forming an assembly for a bag, container or the like. In one embodiment of the disclosure, the polyethylene copolymer composition is used in the formation of molded articles. For example, articles formed by continuous compression molding and injection molding are contemplated. Such articles include, for example, caps, screw-on caps, and bottle closures. Closures The terms cap and closure are used interchangeably in the present description, and both suggest any molded article of suitable shape for enclosing, sealing, closing, or covering, etc., a suitably shaped opening, a suitably molded opening, an open neck structure, or the like used in combination with a container, a bottle, a jar, a bag, and the like. Closures include one-piece closures or closures comprising more than one piece. In one embodiment of the disclosure, the polyethylene copolymer compositions described above are used in forming a closure. In one embodiment of the disclosure, the polyethylene copolymer compositions described above are used in forming the one-piece closure. In one embodiment of the disclosure, the polyethylene copolymer compositions described above are used in the formation of a closure having a tamper-evident band (a TEB). In one embodiment of the disclosure, the polyethylene copolymer composition described above is used to form a closure for bottles, containers, bags, and the like. For example, bottle closures formed by compression molding or injection molding are contemplated. Such closures include, for example, hinged caps, hinged screw-on caps, hinged snap-on caps, and hinged closures for bottles, containers, bags, and the like. In one embodiment of the disclosure, the polyethylene copolymer compositions described above are used in forming a bottle closure assembly comprising a cap portion, a clamp portion, and a retaining means portion. In one embodiment of the disclosure, a closure (or cap) is a screw-on lid for a bottle, container, bag, and the like. In one embodiment of the disclosure, a closure (or cap) is a snap closure for a bottle, container, bag, and the like. In one embodiment of the disclosure, a closure (or lid) comprises a hinge made of the same material as the remainder of the closure (or lid). In one embodiment of the disclosure, a closure (or lid) is a hinged closure. In one embodiment of the disclosure, a closure (or lid) is a hinged closure for bottles, containers, bags, and the like. In one embodiment of the disclosure, a closure (or cap) is for packaging, hot fill, aseptic fill, and cold fill applications. In one embodiment of the disclosure, a closure (or lid) is a hinged, flip-top closure, such as a hinged, flip-top closure for use on a plastic ketchup bottle or similar container containing food products. When a closure is a hinged closure, it comprises a hinged component and generally consists of at least two bodies connected by at least one thinner section that acts as a so-called living hinge, allowing the at least two bodies to bend from an initially molded position. The thinner section(s) may be continuous or band-shaped, wide or narrow. A useful closure (for bottles, containers and the like) is a hinged closure and may consist of two bodies joined together by at least one thinner flexible portion (e.g. the two bodies may be joined by a single bridge portion, or more than one bridge portion, or by a membrane portion, etc.). A first body may contain a dispensing orifice and which may be snapped or screwed onto a container to cover a container opening (e.g. a bottle opening) whilst a second body may function as a snap-on cap engageable with the first body. Caps and closures, of which hinged caps and closures and screw-on caps are a subassembly, may be manufactured according to any known method, including, for example, injection molding and compression molding techniques that are sufficiently known to those skilled in the art. Thus, in one embodiment of the disclosure, a closure (or cap) comprising the polyethylene copolymer composition (defined above) is prepared by a process comprising at least one compression molding step and / or at least one injection molding step. In one embodiment, the caps and closures (including single-piece and multi-piece variants and hinged variants) comprise the polyethylene copolymer composition described above, which has good barrier properties as well as good processability. Therefore, the closures and caps of this embodiment are well-suited for sealing bottles, containers, and the like, for example, bottles that may contain liquids or foods that are susceptible to decomposition (e.g., due to contact with oxygen), including, but not limited to, liquids under appropriate pressure (in this case, carbonated beverages or appropriately pressurized drinkable liquids). Closures and caps can also be used to seal bottles containing drinking water or non-carbonated beverages (e.g., juices). Other applications include caps and closures for bottles, containers, and bags containing food products, such as ketchup bottles and the like. Closures and covers can be one-piece closures or two-piece closures comprising a closure and a liner. The closures and caps may also have a multi-layer design, wherein the cap closure comprises at least two layers, at least one of which is made from the polyethylene blends described herein. In one embodiment of the disclosure, the closure is produced by continuous compression molding. In one embodiment of the disclosure, the closure is produced by injection molding. A closure as described herein may be suitable for use in a container sealing process comprising one or more steps in which the closure comes into contact with a liquid at elevated temperatures, such as hot-fill processes, and in some cases an aseptic filling process. Such closures and processes are described, for example, in Canadian Patent Application Nos. 2,914,353; 2,914,354; and 2,914,315. In one embodiment of the disclosure, a closure made is a CSD PCO 1881 closure, having a weight of about 2.15 grams and having the following dimensions: Closure height (not including tamper evident ring) = about 10.7 mm; Closure height with tamper evident ring = about 15.4 mm; Outside diameter at 4 mm = about 29.6 mm; Thread diameter = about 25.5 mm; Butt seal diameter = about 24.5 mm; Butt seal thickness = about 0.7 mm; Butt seal height to center of biconical ring = about 1.5 mm; Hole seal diameter = about 22.5 mm; Hole seal thickness = about 0.9 mm; Hole height to center of biconical ring = about 1.6 mm; Top panel thickness = about 1.2 mm; Tamper evident band cutout diameter = about 26.3 mm; Thread depth = approximately 1.1 mm; Thread pitch = approximately 2.5 mm; Thread root at 4 mm = 27.4 mm. In one embodiment of the disclosure, a closure is manufactured using an injection molding process to prepare a CSD PCO 1881 closure, having a weight of about 2.15 grams and having the following dimensions: Closure height (not including tamper evident ring) = about 10.7 mm; Closure height with tamper evident ring = about 15.4 mm; Outside diameter at 4 mm = about 29.6 mm; Thread diameter = about 25.5 mm; Butt seal diameter = about 24.5 mm; Butt seal thickness = about 0.7 mm; Butt seal height to center of biconical ring = about 1.5 mm; Hole seal diameter = about 22.5 mm; Hole seal thickness = about 0.9 mm; Hole height to center of biconical ring = about 1.6 mm; Top panel thickness = about 1.2 mm; Tamper-evident strip cutout diameter = approximately 26.3 mm; Thread depth = approximately 1.1 mm; Thread pitch = approximately 2.5 mm; Thread root at 4 mm = 27.4 mm. In one embodiment of the disclosure, a closure is manufactured using a continuous compression molding process to prepare a CSD PCO 1881 closure, having a weight of about 2.15 grams and having the following dimensions: Closure height (not including tamper evident ring) = about 10.7 mm; Closure height with tamper evident ring = about 15.4 mm; Outside diameter at 4 mm = about 29.6 mm; Thread diameter = about 25.5 mm; Butt seal diameter = about 24.5 mm; Butt seal thickness = about 0.7 mm; Butt seal height to center of biconical ring = about 1.5 mm; Hole seal diameter = about 22.5 mm; Hole seal thickness = about 0.9 mm; Hole height to center of biconical ring = about 1.6 mm; Top panel thickness = about 1.2 mm; Tamper-evident strip cutout diameter = approximately 26.3 mm; Thread depth = approximately 1.1 mm; Thread pitch = approximately 2.5 mm; Thread root at 4 mm = 27.4 mm. In embodiments of the disclosure, a closure is produced using a molding process to prepare a CSD PCO 1881 closure having an oxygen transmission rate, OTR, of <0.0035 cm3 / closure / day, or <0.0032 cm3 / closure / day, or <0.0030 cm3 / closure / day, or <0.0029 cm3 / closure / day, <0.0028 cm3 / closure / day, or <0.0027 cm3 / closure / day. In one embodiment of the disclosure, a closure is produced using a continuous compression molding process to prepare a CSD PCO 1881 closure having an oxygen transmission rate, OTR, of <0.0035 cm3 / closure / day, or <0.0032 cm3 / closure / day, or <0.0030 cm3 / closure / day, or <0.0029 cm3 / closure / day, <0.0028 cm3 / closure / day, or <0.0027 cm3 / closure / day. In one embodiment of the disclosure, the closure is manufactured by an injection molding process to prepare a CSD PCO 1881 closure having an oxygen transmission rate, OTR, of <0.0035 cm3 / closure / day, or <0.0032 cm3 / closure / day, or <0.0030 cm3 / closure / day, or <0.0029 cm3 / closure / day, <0.0028 cm3 / closure / day, or <0.0027 cm3 / closure / day. In embodiments of the disclosure, a closure is produced using a molding process to prepare a CSD PCO 1881 closure having an oxygen transmission rate, OTR, of from 0.0016 to 0.0035 cm / closure / day inclusive of any narrower range within this range and any values ​​within these ranges. For example, in embodiments of the disclosure, a closure is produced using a molding process to prepare a CSD PCO 1881 closure having an oxygen transmission rate, OTR, of from 0.0018 to 0.0034 cm / closure / day, or from 0.0018 to 0.0032 cm / closure / day, or from 0.0018 to 0.0030 cm / closure / day, or from 0.0020 to 0.0030 cm / closure / day. In one embodiment of the disclosure, a closure is produced using a continuous compression molding process to prepare a CSD PCO 1881 closure having an oxygen transmission rate, OTR of from 0.0016 to 0.0035 cm3 / closure / day inclusive of any narrower range within this range and any values ​​encompassed by these ranges. For example, in embodiments of the disclosure, a closure is produced using a continuous compression molding process to prepare a CSD PCO 1881 closure having an oxygen transmission rate, OTR, of from 0.0018 to 0.0034 cm3 / closure / day, or from 0.0018 to 0.0032 cm3 / closure / day, or from 0.0018 to 0.0030 cm3 / closure / day, or from 0.0020 to 0.0030 cm3 / closure / day. In one embodiment of the disclosure, a closure is produced using an injection molding process to prepare a CSD PCO 1881 closure having an oxygen transmission rate, OTR, of from 0.0016 to 0.0035 cm / closure / day inclusive of any narrower range within this range and any values ​​within these ranges. For example, in embodiments of the disclosure, a closure is made using an injection molding process to prepare a CSD PCO 1881 closure having an oxygen transmission rate, OTR, of from 0.0018 to 0.0034 cm / closure / day, or from 0.0018 to 0.0032 cm / closure / day, or from 0.0018 to 0.0030 cm / closure / day, or from 0.0020 to 0.0030 cm / closure / day. Casting Film (and Lamination) In one embodiment of the disclosure, the polyethylene copolymer compositions described above are used in the formation of a cast film or laminated film. Cast films are extruded from a flat die onto a chilled roll or a dot roll, optionally equipped with a vacuum hopper and / or an air knife. The films can be single-layer or coextruded multilayer films obtained by various extrusions through one or more dies. The resulting films can be used as is or can be laminated to other films or substrates, for example, by thermal or adhesive lamination, or by direct extrusion onto a substrate. The resulting films and laminates can then be subjected to further forming operations such as embossing, stretching, or thermoforming. Surface treatments such as corona can be applied, and the films can be printed. In the cast film extrusion process, a thin film is extruded through a slit onto a chilled and highly polished rotating roll, where it is cooled from one side.The roll speed controls the draw ratio and final film thickness. The film is then sent to a second roll for cooling on the other side. Finally, it passes through a roller system and is wound into a roll. In another embodiment, two or more thin films are coextruded through two or more slits in a cooled, highly polished rotating roll; the coextruded film is cooled on one side. The roll speed controls the draw ratio and final thickness of the coextruded film. The coextruded film is then sent to a second roll for cooling on the other side. Finally, it passes through a roller system and is wound into a roll. In one embodiment, the cast film product may be further laminated into one or more layers in a multi-layer structure. Cast films and laminates can be used for a variety of purposes, for example, food packaging (dry foods, fresh foods, frozen foods, liquids, processed foods, powders, granules), for packaging detergents, toothpaste, wipes, and for labels and release liners. The films can also be used in industrial packaging and unbundling, especially in stretch films. The films may also be suitable for hygienic and medical applications, for example, in breathable and non-breathable films used in diapers, adult incontinence products, feminine hygiene products, and ostomy bags. Finally, cast films can also be used in tapes and artificial turf applications. In embodiments of the disclosure, a film layer or film has a normalized oxygen transmission rate, OTR, of < 130 cm3 / 645.16 cm2(100 pg2) / day, or < 125 cm3 / 645.16 cm2(100 pg2) / day, or 120 cm3 / 645.16 cm2(100 pg2) / day. In embodiments of the disclosure, a compression molded film or film layer has a normalized oxygen transmission rate, OTR, of ≥130 cm3 / 645.16 cm2(100 µg2) / day, or <125 cm3 / 645.16 cm2(100 µg2) / day, or <120 cm3 / 64 5.16 cm2(100 µg2) / day. In embodiments of the disclosure, a cast film or film layer has a normalized oxygen transmission rate, OTR, of ≥130 cm3 / 645.16 cm2(100 µg2) / day, or <125 cm3 / 645.16 cm2(100 µg2) / day, or <120 cm3 / 645.16 cm2(100 µg2) / day. In embodiments of the disclosure, a film or laminating film layer has a normalized oxygen transmission rate, OTR, of < 130 cm3 / 645.16 cm2(100 pg2) / day, or 125 cm3 / 645.16 cm2(100 pg2) / day, or 120 cm3 / 64 5.16 cm2(100 pg2) / day. In embodiments of the disclosure, a film layer or film has a normalized oxygen transmission rate, OTR, of from 50 to 140 cm3 / 645.16 cm2 (100 pg2) / day, including any narrower range within this range and any values ​​encompassed by these ranges. For example, in embodiments of the disclosure, a film layer or film has a normalized oxygen transmission rate, OTR, of from 60 to 130 cm3 / 645.16 cm2 (100 µg2) / day, or from 70 to 130 cm3 / 645.16 cm2 (100 µg2) / day, or from 70 to 120 cm3 / 645.16 cm2 (100 µg2) / day, or from 80 to 130 cm3 / 645.16 cm2 (100 µg2) / day, or from 80 to 120 cm3 / 645.16 cm2 (100 µg2) / day. In embodiments of the disclosure, a compression molded film or film layer has a normalized oxygen transmission rate, OTR, of from 50 to 140 cm3 / 645.16 cm2 (100 µg2) / day, including any narrower range within this range and any values ​​encompassed by these ranges. For example, in embodiments of the disclosure, a film or compression molded layer film has a normalized oxygen transmission rate, OTR, of from 60 to 130 cm3 / 645.16 cm2 (100 µg2) / day, or from 70 to 130 cm3 / 645.16 cm2 (100 µg2) / day, or from 70 to 120 cm3 / 645.16 cm2 (100 µg2) / day, or from 80 to 130 cm3 / 645.16 cm2 (100 µg2) / day, or from 80 to 120 cm3 / 645.16 cm2 (100 µg2) / day. In embodiments of the disclosure, a cast film or film layer has a normalized oxygen transmission rate, OTR, of from 50 to 140 cm3 / 645.16 cm2 (100 µg2) / day, including any narrower range within this range and any values ​​encompassed by these ranges. For example, in embodiments of the disclosure, a film or cast film layer has a normalized oxygen transmission rate, OTR, of from 60 to 130 cm3 / 100 µg / day, or from 70 to 130 cm3 / 100 µg / day, or from 70 to 120 cm3 / 100 µg / day, or from 80 to 130 cm3 / 100 µg / day, or from 80 to 120 cm3 / 100 µg / day. In embodiments of the disclosure, a film or laminating film layer has a normalized oxygen transmission rate, OTR, of from 50 to 140 cm3 / 645.16 cm2 (100 pg2) / day, including any narrower range within this range and any values ​​encompassed by these ranges. For example, in embodiments of the disclosure, a film or laminating film layer has a normalized oxygen transmission rate, OTR, of from 60 to 130 cm3 / 645.16 cm2 (100 µg2) / day, or from 70 to 130 cm3 / 645.16 cm2 (100 µg2) / day, or from 70 to 120 cm3 / 645.16 cm2 (100 µg2) / day, or from 80 to 130 cm3 / 645.16 cm2 (100 µg2) / day, or from 80 to 120 cm3 / 645.16 cm2 (100 µg2) / day. In modalities of the description, a film or film layer has a normalized water vapor transmission rate, WVTR of < 0.340 g / 645 cm2(100 pg2) / day, or < 0.320 g / 645 cm2(100 pg2) / day, or < 0.310 g / 645 cm2(100 pg2) / day, or < 0.300 g / 645 cm2(100 pg2) / day, or < 0.298 g / 645 cm2(100 pg2) / day, or < 0.296 g / 645 cm2(100 pg2) / day. In modalities of the description, a compression molded film or film layer has a normalized water vapor transmission rate, WVTR of < 0.340 g / 645 cm2(100 pg2) / day, or < 0.320 g / 645 cm2(100 pg2) / day, or < 0.310 g / 645 ccr? nn / Lznz / E / YiA cm2(100 pg2) / dia, or < 0.300 g / 645 cm2(100 pg2) / dia, or < 0.2 98 g / 645 cm2(100 pg2) / dia, or < 0.2 96 g / 645 cm2(100 pg2) / dia. In embodiments of the disclosure, a film or cast film layer has a normalized water vapor transmission rate, WVTR, of <0.340 g / 645 cm2(100 pg2) / day, or <0.320 g / 645 cm2(100 pg2) / day, or <0.310 g / 645 cm2(100 pg2) / day, or <0.300 g / 645 cm2(100 pg2) / day, or <0.298 g / 645 cm2(100 pg2) / day, or <0.296 g / 645 cm2(100 pg2) / day. In embodiments of the disclosure, a film or laminating film layer has a normalized water vapor transmission rate, WVTR, of <0.340 g / 645 cm2(100 pg2) / day, or <0.320 g / 645 cm2(100 pg2) / day, or <0.310 g / 645 cm2(100 pg2) / day, or <0.300 g / 645 cm2(100 pg2) / day, or <0.298 g / 645 cm2(100 pg2) / day, or <0.296 g / 645 cm2(100 pg2) / day. In embodiments of the disclosure, a film or film layer has a normalized water vapor transmission rate, WVTR, of from 0.150 to 0.340 g / 645 cm2 (100 pg2) / day, including narrower ranges within this range and any values ​​encompassed by these ranges. For example, in embodiments of the disclosure, a film or film layer has a normalized water vapor transmission rate, WVTR, of from 0.160 to 0.340 g / 645 cm2 (100 pg2) / day, or from 0.170 to 0.340 g / 645 cm2 (100 pg2) / day, or from 0.170 to 0.330 g / 645 cm2 (100 pg2) / day, or from 0.180 to 0.330 g / 645 cm2 (100 pg2) / day, or from 0.180 to 0.320 g / 645 ccr? nn / Lznz / E / YiA cm2(100 pg2) / day, or from 0.190 to 0.320 g / 645 cm2(100 pg2) / day. In embodiments of the disclosure, a compression molded film or film layer has a normalized water vapor transmission rate, WVTR, of from 0.150 to 0.340 g / 645 cm2 (100 pg2) / day, including narrower ranges within this range and any values ​​encompassed by these ranges. For example, in embodiments of the disclosure, a compression molded film or film layer has a normalized water vapor transmission rate, WVTR, of from 0.160 to 0.340 g / 645 cm2 (100 pg2) / day, or from 0.170 to 0.340 g / 645 cm2 (100 pg2) / day, or from 0.170 to 0.330 g / 645 cm2 (100 pg2) / day, or from 0.180 to 0.330 g / 645 cm2 (100 pg2) / day, or from 0.180 to 0.320 g / 645 cm2 (100 pg2) / day, or from 0.190 to 0.320 g / 645 cm2 (100 pg2) / day. In embodiments of the disclosure, a film or cast film layer has a normalized water vapor transmission rate, WVTR, of from 0.150 to 0.340 g / 645 cm2 (100 pg2) / day, including narrower ranges within this range and any values ​​encompassed by these ranges. For example, in embodiments of the disclosure, a cast film or film layer has a normalized water vapor transmission rate, WVTR, of from 0.160 to 0.340 g / 645 cm2 (100 µg2) / day, or from 0.170 to 0.340 g / 645 cm2 (100 µg2) / day, or from 0.170 to 0.330 g / 645 cm2 (100 µg2) / day, or from 0.180 to 0.330 g / 645 cm2 (100 µg2) / day, or from 0.180 to 0.330 g / 645 cm2 (100 µg2) / day, or from 0.180 to 0.34 ... 0.320 g / 645 cm2(100 pg2) / day, or from 0.190 to 0.320 g / 645 cm2(100 pg2) / day. In embodiments of the disclosure, a film or laminating film layer has a normalized water vapor transmission rate, WVTR, of from 0.150 to 0.340 g / 645 cm2 (100 pg2) / day, including narrower ranges within this range and values ​​encompassed by these ranges. For example, in embodiments of the disclosure, a film or laminating film layer has a normalized water vapor transmission rate, WVTR, of from 0.160 to 0.340 g / 645 cm2 (100 pg2) / day, or from 0.170 to 0.340 g / 645 cm2 (100 pg2) / day, or from 0.170 to 0.330 g / 645 cm2 (100 pg2) / day, or from 0.180 to 0.330 g / 645 cm2 (100 pg2) / day, or from 0.180 to 0.320 g / 645 cm2 (100 pg2) / day, or from 0.190 to 0.320 g / 645 cm2 (100 pg2) / day. The following examples provide further non-limiting details of the description. The examples are presented for the purpose of illustrating selected embodiments of this description, it being understood that the examples presented do not limit the claims presented. EXAMPLES General Methods of Polymer Characterization Before testing, each specimen was conditioned for at least 24 hours at 23 ± 2°C and 50 ± 10% relative humidity, and subsequent tests were conducted at 23 ± 2°C and ± 10% relative humidity. In this document, the term "ASTM conditions" refers to a laboratory maintained at 23 ± 2°C and 50 ± 10% relative humidity; and the specimens to be tested were conditioned for at least 24 hours in this laboratory prior to testing. ASTM refers to the American Society for Testing and Materials. Density was determined using ASTM D792-13 (November 1, 2013). The melt index was determined using ASTM D1238 (August 1, 2013). The melt indices, I2, le, lio, and I21 were measured at 190°C, using weights of 2.16 kg, 6.48 kg, 10 kg, and 21.6 kg, respectively. Here, the term stress exponent, or its acronym S.Ex., is defined by the following relationship: S.Ex. = log(Ie / l2) / log(648 0 / 2160); where le and I2 are the melt flow indices measured at 190°C using loads of 6.48 kg and 2.16 kg, respectively. Mn, Mw, and Mz(g / mol) were determined by high-temperature gel permeation chromatography (GPC) with differential refractive index (DRI) detection using a universal calibration (e.g., ASTM-D6474-99). GPC data were obtained using an instrument sold under the tradename Waters 150c, with 1,2,4-trichlorobenzene as the mobile phase at 140°C. Samples were prepared by dissolving the polymer in this solvent and processed without filtration. Molecular weights are expressed as polyethylene equivalents with a relative standard deviation of 2.9% for number-average molecular weight (Mn) and 5.0% for weight-average molecular weight (Mw). The molecular weight distribution (MWD) is the weight-average molecular weight divided by the number-average molecular weight, Mw / Mn. The z-average molecular weight distribution is Mz / Mn.Polymer sample solutions (1 to 2 mg / mL) were prepared by heating the polymer in 1,2,4-trichlorobenzene (TCB) and wheel spinning for 4 hours at 150°C in an oven. The antioxidant 2,6-di-tert-butyl-4-methylphenol (BHT) was added to the mixture to stabilize the polymer against oxidative degradation. The BHT concentration was 250 ppm. The sample solutions were chromatographed at 140°C in a PL 220 high temperature chromatography unit equipped with four Shodex® columns (HT803, HT804, HT805 and HT806) using TCB as the mobile phase at a flow rate of 1.0 mL / minute, with a differential refractive index (DRI) concentration detector. BHT was added to the mobile phase at a concentration of 250 ppm to protect the columns from oxidative degradation. The sample injection volume was 200 mL. Raw data were processed using CIRRUS® GPC software.The columns were calibrated with narrow-distribution polystyrene standards. Polystyrene molecular weights were converted to polyethylene molecular weights using the Mark-Houwink equation, as described in ASTM D6474. The high-temperature GPC equipped with an online FTIR detector (GPC-FTIR) was used to measure comonomer content as a function of molecular weight. The primary melting peak (°C), heat of fusion (J / g), and crystallinity (%) were determined using differential scanning calorimetry (DSC) as follows: the instrument was first calibrated with indium; after calibration, a polymer specimen was equilibrated at 0°C and then the temperature was increased to 200°C at a heating rate of 10°C / min; the melt was then held isothermally at 200°C for five minutes; the melt was then cooled to 0°C at a cooling rate of 10°C / min and held at 0°C for five minutes; the sample was then heated to 200°C at a heating rate of 10°C / min. The DSC Tm, heat of fusion, and crystallinity were reported from the 2nd heating cycle. The short chain branching frequency (SCB per 1000 carbon atoms) of the polyethylene composition was determined by Fourier transform infrared spectroscopy (FTIR) according to ASTM D6645-01. A Thermo-Nicolet Magna 750-IR spectrophotometer equipped with OMNIC® version 7.2a software was used for the measurements. Unsaturations in the polyethylene composition were also determined by Fourier transform infrared spectroscopy (FTIR) according to ASTM D3124-98. Hexane extractables were determined according to ASTM D5227. Shear viscosity was measured using a Kayeness WinKARS capillary rheometer (model # D5052M-115). For shear viscosity at lower shear rates, a die having a die diameter of 1.524 mm (0.06 in.) and an L / D ratio of 20 and a gate angle of 180 degrees was used. For shear viscosity at higher shear rates, a die having a die diameter of 0.3048 mm (0.012 in.) and an L / D ratio of 20 was used. The Shear Viscosity Ratio as the term is used in the present description is defined as: ηιοο / ηιοοοοο at 240°C. The processability indicator is defined as 100 / ηιοοοοο. The ηιοο is the melt shear viscosity at the shear rate of 100 s-1 and the ηιοοοοο is the melt shear viscosity at the shear rate of 100000 s-1 measured at 240°C. The processability indicator, as used here, is defined as: Processability indicator = 100 / η (105s-1, 240°C); where η is the shear viscosity measured at 105 1 / s at 240°C. Dynamic mechanical analyses were performed using a rheometer, called Rheometrics Dynamic Spectrometer (RDS-II) or Rheometrics SR5 or ATS Stresstech, on compression molded samples under a nitrogen atmosphere at 190°C, using a 25 mm diameter cone and plate geometry. Oscillatory shear experiments were performed within the linear viscoelastic deformation range (10% strain) at frequencies from 0.05 to 100 rad / s. Values ​​of storage modulus (G'), loss modulus (G''), complex modulus (G*), and complex viscosity (η*) were obtained as a function of frequency. The same rheological data can also be obtained using a 25 mm diameter parallel plate geometry at 190°C in a nitrogen atmosphere. The zero shear viscosity is estimated using the Ellis model, in this case η (ω ) = ηο / (1 + τ / τι / 2)“-1' where ηο is the zero shear viscosity.Ti / 2 is the shear stress value at which η = ηο / 2 and is one of the adjustable parameters. The Cox-Merz rule is assumed to be applicable in the present description. The SHI (1,100) value is calculated according to the methods described in WO 2006 / 048253 and WO 2006 / 048254. The DRI is the Dow rheology index and is defined by the equation: DRI = [365000 (το / ηο)-1 ] / 10; where To is CCR? ΠΠ / ίΖΠΖ / Ε / ΥΙΛ is the characteristic relaxation time of polyethylene, and ηο is the zero shear viscosity of the material. The DRI is calculated by least squares fitting of the rheological curve (dynamic complex viscosity versus applied frequency, e.g., 0.01-100 rads / s) as described in U.S. Patent No. 6,114,486 with the following generalized Cross equation, in this case, η (ω) =ηο / [ 1+ (ωτο)n] ; where n is the power law index of the material, η(ω) and ω are the measured complex viscosity and applied frequency data, respectively. In determining the DRI, the zero shear viscosity, ηο used was estimated with the Ellis model, rather than the Cross model. The crossover frequency is the frequency at which the storage modulus (G') and loss modulus (G'') curves cross each other, while G' at G'' = 500Pa is the storage modulus at which the loss modulus (G'') is 500 Pa. To determine the CDBI(50), a solubility distribution curve is first generated for the polyethylene composition. This is accomplished using data acquired with the TREF technique. This solubility distribution curve is a plot of the weight fraction of the copolymer that is solubilized as a function of temperature. This is converted to a cumulative distribution curve of weight fraction versus comonomer content, from which the CDBI(50) is determined by establishing the weight percent of a copolymer sample that has a comonomer content within 50% of the mean comonomer content on either side of the median (See WO 93 / 03093 and U.S. Patent No. 5,376,439).Those skilled in the art will understand that a calibration curve is required to convert a TREF elution temperature to comonomer content, in this case, the amount of comonomer in the polyethylene composition fraction eluting at a specified temperature. The generation of such calibration curves is described in the prior art, e.g., Wild, et al., J. Polym. Sci., Part B, Polym. Phys., Vol. 20(3), pp. 441-455: herein fully incorporated by reference. The CDBI(25) is determined by establishing the weight percent of a copolymer sample having a comonomer content within 25% of the median comonomer content on either side of the median. The temperature rising elution fractionation (TREF) method used in this paper was as follows. Polymer samples (50 to 150 mg) were introduced into the reactor vessel of a TREF-crystallization unit (Polymer Char, Valencia Technology Park, Gustavo Eiffel, 8, Paterna, E-46980 Valencia, Spain) equipped with an IR detector. The reactor vessel was filled with 20 to 40 mL of 1,2,4-trichlorobenzene (TCB), and heated to the desired dissolution temperature (e.g., 150°C) for 1 to 3 hours. The solution (0.5 to 1.5 ml) was then loaded onto a TREF column packed with stainless steel beads. After equilibrating at a given stabilization temperature (e.g., 110°C) for 30 to 45 minutes, the polymer solution was allowed to crystallize with a temperature drop from the stabilization temperature to 30°C (0.1 or 0.2°C / minute). After equilibrating at 30°C for 30 minutes, the crystallized sample was eluted with TCB (0.5 or 0.75 ml / minute) with a temperature ramp from 30°C to the stabilization temperature (0.25 or 1.0°C / minute). The TREF column was cleaned at the end of the cycle for 30 minutes at dissolution temperature. Data were processed using the Polymer Char software, EXCEL® spreadsheet, and the TREF software developed in-house.Using the computer program Polymer Char, a TREF distribution curve was generated as the polyethylene composition eluted from the TREF column, in this case, a TREF distribution curve is a plot of the amount (or intensity) of polyethylene composition eluting from the column as a function of TREF elution temperature. The TREF-crystallization was operated in the TREF mode, which generated the chemical composition of the polymer sample as a function of elution temperature, Co / Ho ratio (Copolymer / Homopolymer ratio), CDBI (Composition Distribution Breadth Index), in this case CDBI (50) and CDBI (25), the location of a high temperature elution peak (in °C), and the approximate amount of a high density fraction (an HD fraction, in weight percent) eluting at a temperature of 95 to 105 °C. Molded plates from the polyethylene copolymer compositions were tested according to the following ASTM methods: Environmental Strip Bend Stress Crack Resistance (ESCR) under Condition B at 100% Igepal at 50°C, ASTM D1693; Notched Izod Impact Properties, ASTM D256; Flexural Properties, ASTM D790; Tensile Properties, ASTM D638; Vicat Softening Point, ASTM D1525; Heat Deflection Temperature, ASTM D648. Examples of the polyethylene copolymer compositions were produced in a dual-reactor solution polymerization process where the contents of the first reactor flow into the second reactor. This dual-reactor-in-series process produces a polyethylene blend in situ (in this case, the polyethylene composition). Note that when a series reactor configuration is used, unreacted ethylene monomer and unreacted alpha-olefin comonomer present in the first reactor will flow downstream to the second reactor for further polymerization. In the present examples of the invention, although no comonomer is fed directly to the second downstream reactor, an ethylene copolymer is nevertheless formed in the second reactor due to the significant presence of unreacted 1-octene flowing from the first reactor to the second reactor where it is copolymerized with ethylene. Each reactor is sufficiently agitated to provide conditions under which the components are sufficiently mixed. The volume of the first reactor was 12 liters and the volume of the second reactor was 22 liters. These are pilot plant scales. The first reactor was operated at a pressure of 10,500 to 35,000 kPa and the second reactor was operated at a lower pressure to facilitate continuous flow from the first reactor to the second. The solvent employed was methylpentane. The process operates with the use of continuous feed streams.The catalyst employed in the dual reactor solution process experiments was a phosphinimine catalyst, which was a titanium complex having a phosphinimine ligand ((tert-butyl)sP=N), a cyclopentadienide (Cp) ligand, and two activatable ligands (chloride ligands; note: activatable ligands are removed by, for example, electrophilic abstraction using a cocatalyst or activator to generate an active metal center). A boron-based cocatalyst (PhsCB(CeFs)4) was used in approximately stoichiometric amounts with respect to the titanium complex. Commercially available methylaluminoxane (MAC) was included as a scavenger at an Al:Ti ratio of approximately 40:1. Furthermore, 2,6-di-tert-butylhydroxy-4-ethylbenzene was added to remove free trimethylaluminum within the MAO at an Al:OH ratio of approximately 0.5:1.The polymerization conditions used to prepare the polyethylene copolymer compositions of the invention are provided in Table 1. The polyethylene copolymer compositions of Examples 1 and 2 are prepared using a single-site phosphinimine catalyst in a dual-reactor solution process as described above. As can be seen in Figure 1, Examples 1 and 2 of the invention have a bimodal molecular weight distribution or profile in a GPC analysis (there is a main peak area, but it is flanked by a shoulder area in the GPC chromatograph). Comparative polyethylene copolymer compositions, Examples 3, 4 and 5 were prepared in a dual reactor solution polymerization process using a phosphinimine catalyst, as described in Co-Pending Canadian Patent Application No. 3,028,157. The properties of the inventive polyethylene composition as well as the comparative nucleated and non-nucleated ones are provided in Table 2. The inventive nucleated resins (Examples 1 and 2) and comparative nucleated resins (Examples 3-5) indicated in the Tables by the symbol were prepared as follows. A 4% (by weight) masterbatch of the nucleating agent HYPERFORM® HPN-20E from Milliken Chemical was first prepared. This masterbatch also contained 1% (by weight) of DHT-4V (aluminum magnesium carbonate hydroxide) from Kisuma Chemicals. The base resin and nucleating agent masterbatch were melt blended using a Coperion ZSK 26 co-rotating twin screw extruder with an L / D of 32:1 to give a polyethylene composition having 1200 parts per million (ppm) of HYPERFORM HPN-20E Nucleating Agent present (based on the weight of the polyethylene composition).The extruder was equipped with an underwater pelletizer and a Gala rotary dryer. The materials were co-fed to the extruder using gravimetric feeders to achieve the desired nucleating agent level. The blends were combined using a screw speed of 200 rpm at a production rate of 15-20 kg / h and a melt temperature of 225-230°C. Some calculated properties for the first ethylene copolymer and the second ethylene copolymer present in each of the inventive polyethylene copolymer compositions (Examples 1 and 2) are provided in Table 3 (see Polymerization Reactor Modeling below for methods of calculating these properties). For comparison purposes, Table 3 also includes some calculated properties for the first and second ethylene copolymers present in the comparative polyethylene compositions of Examples 3 through 5. The properties of pressed plates prepared from nucleated and non-nucleated polyethylene copolymer compositions of the invention, as well as comparative compositions, are provided in Table 4. Modeling of Polymerization Reactors For multi-component polyethylene polymers (or bimodal resins) with very low comonomer contents, it can be difficult to reliably estimate the short chain branching (and subsequently the polyethylene resin density by combining other information) of each polymer component by mathematical deconvolution of the GPC-FTIR data, as was done, for example, in U.S. Patent No. 8,022,143. Instead, the Mw, Mn, Mz, Mw / Mn, and short chain branching per thousand carbons (SCB / 1000C) of the first and second copolymers were calculated here using a reactor model simulation using inlet conditions that were employed for actual pilot-scale run conditions (for references on relevant reactor modeling methods, see A. Hamielec, J. MacGregor and A. Penlidis in Comprehensive Polymer Science and Supplements, volume 3, Chapter 2, page 17, Elsevier, 1996 and olefin copolymerization in a series of continuous stirred tank slurry reactors using heterogeneous Ziegler-Natta and metallocene catalysts. General dynamic mathematical model by J.P.P. Soares and A.E. (Hamielec in Polymer Reaction Engineering, 4 (2 and 3), pl53, 1996.) This type of model is considered reliable for the estimation of comonomer (e.g., 1-octene) content even at low comonomer incorporation levels, since the ethylene conversion, ethylene inflow, and comonomer inflow can be obtained directly from the experimental conditions and because the reactant ratio (see below) can be reliably estimated for the catalyst system used in the present disclosure.For clarity, the terms monomer or monomer 1 represent ethylene, while the terms comonomer or monomer 2, represent octene. The model takes as input the flow of various reactive species (e.g. catalyst, monomer such as ethylene, comonomer such as 1-octene, hydrogen and solvent) going to each reactor, the temperature (in each reactor) and the monomer conversion (in each reactor) and calculates the polymer properties (of the polymer made in each reactor, in this case the first and second ethylene copolymers) using a terminal kinetic model for continuously stirred tank reactors (CSTRs) connected in series. The terminal kinetic model assumes that the kinetics depend on the monomer unit within the polymer chain on which the active catalyst site is located (see Copolymerization by A. Hamielec, J. MacGregor and A. Penlidis in Comprehensive Polymer Science and Supplements, volume 3, chapter 2, page 17, Elsevier, 1996).In the model, the copolymer chains are assumed to have a reasonably large molecular weight to ensure that the statistics of monomer / comonomer unit insertion into the center of the active catalyst are valid and that monomers / comonomers consumed in pathways other than propagation are negligible. This is known as the long-chain approximation. The terminal kinetic model for polymerization includes reaction rate equations for the activation, initiation, propagation, chain transfer, and deactivation pathways. This model solves the steady-state conservation equations (e.g., total mass balance and heat balance) for the reactant fluid, which includes the reactive species identified above. The total mass balance for a generic CSTR with a given number of inlets and outlets is given by: (1) 0 = If Wi / Where ñi· represents the mass flow rate of the individual streams with index i indicating the inlet and outlet streams. Equation (1) can be further expanded to show the individual species and reactions: / Λ - . V / (2) pmíxV ' Pmix PCR7 nn / ί7Π7 / Ε / ΥΙΛ where Mi is the average molar weight of the fluid inlet or outlet (i), xij is the mass fraction of species j in stream i, pmix is ​​the molar density of the reactor mixture, V is the reactor volume, Rj is the reaction rate for species j, which has units of kmol / m3s. The total heat balance is solved for an adiabatic reactor and is given by: or) 0 = (2^^( + ^7+^-6) where, is the mass flow rate of stream i (inlet or outlet), ΔΗ± is the difference in enthalpy of stream i against a reference state, q^x is the heat released by the reaction(s), V is the reactor volume, W is the work input (in this case, the agitator), Q is the heat input / loss. The catalyst concentration input to each reactor is adjusted to match the experimentally determined ethylene conversion and reactor temperature values ​​in order to solve the kinetic model equations (e.g., propagation rates, heat balance, and mass balance). The input Hz concentration of each reactor can be adjusted in the same way so that the calculated molecular weight distribution of a polymer produced in both reactors (and therefore the molecular weight of the polymer made in each reactor) matches that observed experimentally. The degree of polymerization (DPN) of a polymerization reaction is given by the ratio between the rate of chain propagation reactions and the rate of chain transfer / termination reactions: (4) ........................... [«Ιϊ.ΙΦί+^ίτπΙΪ [^21^1+^^21 [^2.1^2 + ^1^1 + ^(52^2+ktífl Wi where kpi2 is the propagation rate constant for adding monomer 2 to a growing polymer chain terminated with monomer 1, [mi] is the molar concentration of monomer 1 (ethylene) in the reactor, [mi] is the molar concentration of monomer 2 (1-octene) in the reactor, ktmi2 the termination rate constant for chain transfer to monomer 2 for a growing chain terminated with monomer 1, ktsi is the rate constant for spontaneous chain termination for a chain terminating with monomer 1, ktHi is the rate constant for chain termination by hydrogen for a chain terminating with monomer 1. φι and Φ2 and the fraction of the catalyst sites occupied by a chain ending with monomer 1 or monomer 2, respectively. The number-average molecular weight (Mn) of a polymer is derived from the degree of polymerization and the molecular weight of a monomer unit. From the number-average molecular weight of the polymer in each reactor, which assumes a Flory distribution for a single-site catalyst, the molecular weight distribution for the polymer formed in each reactor is determined: (5) w(n) = rne ™ Where τ = 1 , and w(n) is the weight fraction of polymer having chain length n. The Flory distribution can be transformed into the common logarithmic scale GPC trace by applying: ...... ™ m( 10) —e- (6) dio g(M) tW where....................... is the differential weight fraction of the polymer with a chain length n (n = MW / 28 where 28 is the molecular weight of the polymer segment corresponding to a C2H4 unit) and DPN is the degree of polymerization calculated by Equation (4) From the Flory model, the Mwy and Mz of the polymer produced in each reactor are: Mw= 2 x Mn and Mz= 1.5 x Mw. The overall molecular weight distribution in both reactors is simply the sum of the molecular weight distribution of the polymer made in each reactor, where each Flory distribution is multiplied by the weight fraction of polymer made in each reactor: (7) ------= Hb. 10(10)-2-- ]+ivS2ln(10)——je' '««l \ DPNrz and where dW / Dlog (MW) is the overall molecular weight distribution function, Wri and Wr2 are the weight fraction of polymer made in each reactor, DPNi and DPN2 are the average chain length of polymer produced in each reactor (in this case DPNi = MnRi / 28). The weight fraction of material made in each reactor is determined by knowing the mass flow rate of monomer and comonomer in each reactor along with the monomer and comonomer conversions in each reactor. The moments of the overall molecular weight distribution (or the molecular weight distribution of the polymer made in each reactor) can be calculated using equations 8a, 8b and 8c (a Flory model above is assumed, but the following generic formula applies to other model distributions as well): <£ U Ca (8a) The comonomer content in the polymer product (in each reactor) can also be calculated using the terminal kinetic model and the long chain approximations discussed above (see A. Hamielec, J. MacGregor and A. Penlidis. Comprehensive Polymer Science and Supplements, volume 3, chapter Copolymerization, page 17, Elsevier, 1996). For a given catalyst system, the incorporation of comonomer (e.g., 1-octene) is a function of the conversion of monomer (e.g., ethylene), the ratio of comonomer to monomer in the reactor (y), and the reactivity ratio of monomer 1 (e.g., ethylene) over monomer 2 (e.g., 1-octene): yi = kpn / kpi2. For a CSTR, the molar ratio of ethylene to comonomer in the polymer (Y) can be estimated by knowing the reactivity ratio ri of the catalyst system and by knowing the ethylene conversion in the reactor (βπA). A quadratic equation can be derived using the May-Lewis equation for instantaneous comonomer incorporation (see ''Copolymerization'' by A. Hamielec, J. MacGregor and A. Penlidis in Comprehensive Polymer Science and Supplements, volume 3, chapter 2, page 17, Elsevier, 1996) and the mass balance around the reaction solved. The molar ratio of ethylene to 1-octene in the polymer is the negative square root of the following quadratic equation: o> -f2^+[^+5^(1-^) + ^-5^ o where Y is the molar ratio of ethylene to 1-octene in the polymer, γ is the mass flow ratio of 1-octene to ethylene going to the reactor, ri is the reactivity ratio of monomer 1 to monomer 2 for the catalyst system (ri = Kpii / kpi2), and 0^1 is the fractional conversion of ethylene monomer. The branching frequency can be calculated by knowing the molar ratio of monomer 1 to monomer 2 in the polymer: (10) gr=-- where Y is the molar ratio of monomer 1 (ethylene) to monomer 2 (1-octene) in the polymer, and BF is the branching frequency (branches per 1000 carbon atoms). The overall branch frequency distribution (BFD) of the ethylene composition can be calculated by knowing the molecular weight distribution and weight fraction of the polymer produced in each reactor, and the average branch frequency (BF) of the ethylene copolymer produced in each reactor. The polymer fraction produced in each reactor can be calculated from the experimental mass flow rates and the monomer and comonomer conversion in each reactor. The branch frequency distribution function is obtained by calculating the average branch content for each molecular weight value from the overall molecular weight distribution function made from the two Flory distributions: (11) np ..... WfljFj(^1)+ ^2^3 (^^«2 ) where BFm» is the branching in molecular weight (MW) , Wri and Wr2 are the weight fraction of polymer produced in Reactor 1 and Reactor 2, BFri and BFr2 are the average branching frequency of polymer produced in R1 and R2 (from Equations 9 and 10), Fi(MWri) and Fi (MWr2) are the Flory distribution function of Reactor 1 and Reactor 2. The total branching frequency of the polyethylene composition is given by the weighted average of the branching frequency of the polymer produced in each reactor: (12) BFavg — W1BF1 + W2BF2 where, BFavg is the average branching frequency for the total polymer (e.g., the polyethylene composition), wi and W2 are the weight fraction of the material produced in each reactor, BFi and BF2 are the branching frequency of the material produced in each reactor (e.g., the branching frequency of the first and second ethylene copolymers). For the polymer obtained in each reactor, the key resin parameters which are obtained from the kinetic model described above are the molecular weights Mn, Mw and Mz, the molecular weight distributions Mw / Mn and Mz / Mwy and the branching frequency (SCB / 1000 Cs). With this information in hand, a component density (or composition) model and a component melt index (or composition) model, I2, were used according to the following equations, which were determined empirically, to calculate the density and melt index I2 of each of the first and second ethylene copolymers: Density: 0.0303 / C0·9804 - = 1.0142 + 0.0033(1.22+..... ..... p 1 . 0-37121+ íM / í where, BF is the branching frequency, le ~ Logl()í / 1000 / fusion index, I2 (MI): / Mwi Logí0(MI) - 7.8998 - 3.9089Lo5wr-M - 02799-f· \lvvw Therefore, the above models were used to estimate the branching frequency, weight fraction (or weight percent), melt index, and density of the polyethylene composition components formed in each of reactors 1 and 2 (in this case, the first and second ethylene copolymers). TABLE 1 Reactor conditions Example No. 1 2 Reactor 1 Ethylene (kg / h) 29.9 29.9 Octene (kg / h) 5.16 4.13 Hydrogen (g / h) 0.28 0.41 Solvent (kg / h) 244.5 245.6 Reactor Feed Inlet Temperature (°C) 35 35 Reactor Temperature (°C) 165.1 164.7 Titanium Catalyst (ppm) 0.0376 0.0287 Reactor 1 Ethylene Conversion (%) 93 93 Reactor 2 Ethylene (kg / h) 44.9 44.9 Octene (kg / h) 0 0 Hydrogen (g / h) 5.5 5.5 Solvent (kg / h) 225.5 225.5 Feed Inlet Temperature Reactor (°C) 35 35 Reactor Temperature (°C) 200.1 200 Titanium Catalyst (ppm) 0.0743 0.0562 Reactor 2 Ethylene Conversion (%) 86 86 Reactor Pressure (MPa) 16 16 Rate (kg / h) 72.1 71.8 TABLE 2 Resin Properties Example No. 1 1* (Inventive) 2 2* (Inventive) Nucleating Agent None HPN20E None HPN20E Density (g / cm3) 0.9449 0.9466 0.947 0.9489 Density of Base Resin (g / cm3) 0.9449 0.947 Density Increase After Nucleation 0.0017 0.0019 Melt Index (g / Wmln), Base Resin 11.3 11 Melt Index Ie (g / 10min) 46.6 44.7 Melt Index Io(g / 10min) 83 82.1 Melt Index I21 (g / 10min) 300 289 Melt Flow Ratio (I21 / I2) 26.5 26.1 Exponent of Stress 1.29 1.27 Melt Flow Ratio (I10 / I2) 7.57 7.51 Rheological Properties Shear Viscosity (η) at 105s-1 (240°C, Pa-s) 7.2 6.7 100 / η at 10 5 s-1 (240°C), processability indicator 13.9 14.9 Shear Viscosity Ratio η100 / η 100000 (240°C) 37.7 42.1 Zero Shear Viscosity - 190°C (Pa-s) 860.65 854.43 Crossover Frequency: 190°C (rad / s) — — DRI 0.389 0.326 G' at G”= 500Pa 32 26.4 DSC Primary Melting Peak (°C) 126.05 129.02 126.73 130.18 Heat of Fusion (J / g) 196.4 211.6 200.4 211.7 Crystallinity (%) $7 7 Λ 72.95 69.11 73.01 Branching Frequency - FTIR (uncorrected for -CH3 chain end) Branch Freq. (SCB per 1000C) 3.8 3.1 Comonomer ID 1-octene 1-octene Comonomer Content (mol%) 0.8 0.8 Comonomer Content (wt%) 3 3 Internal Unsat. / 100C 0.016 0.016 Side Chain Unsat. / 100C 0.002 0.002 Terminal Unsat. / 100C 0.019 0.019 SLOW CTREE High Elution Peak (°C) 93 93.3. CDBI so 83.6 84.5 Co / Ho 0.40 0.30 HD Fraction - Approx. % by weight (95a105°C) 72.4 79.5 GPC Mn 23563 19814 Mw 55988 54421 Mz 114231 115102 Polydispersity Index (Mw / Mn) 2.38 2.75 Extractables and Regulatory Tests Hexane Extractables (% by weight) - Plate 0.24 0.14 TABLE 2 - CONTINUED Resin Properties Example No. 3 3* 4 4* 5 5* Nucleating Agent None HPN20E None HPN20E None HPN20E Density (g / cm3) 0.9539 0.9564 0.954 0.9569 0.9546 0.9574 Base Resin Density (g / cm3) 0.9539 0.954 0.9546 Density Increase After Nucleation 0.0025 0.0029 0.0028 Melt Index I2 (g / 10min), Base Resin 20.4 13.5 29.1 Melt Index Ie (g / 10min) 75 53.1 103 Melt Index I10 (g / 10min) 141 95 170 Melt Index I21 (g / 10min) 400 312 524 Melt Flow Ratio (121 / I2) 19.6 23.1 18 Stress Exponent 1.19 1.25 1.15 Melt Flow Ratio (110 / I2) 7.73 7.08 6.08 Rheological Properties Shear Viscosity (η) at 105^1 (240°C, Pa-s) 7.3 7.0 7.4 100 / η at 105 si (240°C), processability indicator 13.7 14.3 13.5 Shear Viscosity Ratio ηιοο / ηιοοοο (240°C) 24.1 34.8 16.9 Zero Shear Viscosity - 190°C (Pa-s) 401.46 685.04 276.45 Crossover Frequency: 190°C (rad / s) - - - DRI 0.15 0.243 0.119 G at G”= 500Pa 12.8 20.7 9.2 DSC Primary Melting Peak (°C) 129.84 131.38 130.42 132.03 130.27 132.35 Heat of Fusion (J / g) 218.1 221.1 215.5 247.5 217.2 228.2 Crystallinity (%) 75.2 76.23 74.31 85.34 74.89 78.7 FTIR Branching Frequency (uncorrected for chain end) -CH3) Branching Frequency (SCB per 1000C) 1.8 1.7 1.5 ινΐΛ / a / zuz i / uu rao □ Comonomer ID 1-octene 1-octene 1-octene Comonomer Content (mol%) 0.4 0.3 0.3 Comonomer Content (wt%) 1.4 1.4 1.2 Internal Unsat. / 100C 0.017 0.018 0.017 Side Chain Unsat. / 1 OOC 0 0.001 0 Terminal Unsat. / 1 OOC 0.021 0.022 0.019 SLOW CTREF High Elution Peak (°C) 95.3 95.2 95.4 CDBI so 82.1 83.8 82.3 Co / Ho 0.2 0.1 0.1 HD Fraction - wt% Approx. (95 to 105°C) 87.2 88.8 88.1 GPC Mn 21653 24905 23930 Mw 49521 55953 46233 Mz 89061 109160 76726 Polydispersity Index (Mw / Mn) 2.29 2.25 1.93 Extractables and Regulatory Tests Hexane Extractables (% by weight) - Plate 0.19 0.15 0.14 iviA / a / ¿u¿i / uu j TABLE 3 Properties of Polyethylene Composition Components Example No. 1 2 3 4 5 Density (g / cm3) 0.9449 0.947 0.9539 0.954 0.9546 I2 (g / 10min.) 11.3 11 20.4 13.5 29.1 Stress Exponent 1.29 1.27 1.19 1.25 1.15 MFR (I21 / I2) 26.5 26.1 19.6 23.1 18 Mw / Mn 2.38 2.75 2.29 2.25 1.93 First Ethylene Copolymer Weight Fraction 0.4164 0.4161 0.3066 0.3069 0.3063 Mw 129242 122356 92001 117778 74433 I2 (g / 10min.) 0.32 0.40 1.22 0.46 2.79 SCB1 / 1000C 3.04 2.45 0.625 0.633 0.617 Density, d1 (g / cm3) 0.9282 0.9306 0.9441 0.9417 0.9463 Second Ethylene Copolymer Weight Fraction 0.5836 0.5839 0.6934 0.6931 0.6937 Mw 28316 28885 37539 37851 37179 I2 (g / 10min.) 121.4 112.3 40.3 39.0 41.9 SCB2 / 1000C 1.16 0.93 0.2 0.2 0.2 Density, d2 (g / cm3) 0.952 0.9531 0.957 0.957 0.9571 SCB1 / SCB2 2.62 2.63 3.13 3.17 3.09 Estimated (d2-d1), g / cm3 0.0238 0.0225 0.0129 0.0153 0.0108 TABLE 4 Properties of Plate ινΐΛ / a / zuz i / uu rao □ Example No. 1 1* (Inventive) 2 2* (Inventive) Tensile Properties (plates) Elongation at Yield (%) 9 10 11 9 Dev. Elongation at Yield (%) 0.1 0.1 0 0.2 Strength at Yield (MPa) 24.2 25.6 24.9 26.6 Dev. Strength at Yield (MPa) 0.3 0.1 0.1 0.1 Ultimate Elongation (%) 279 237 441 407 Dev. Maximum Elongation (%) 142 83 31.1 - Ultimate Strength (MPa) 14.4 14.3 14.7 14.5 Dev. Ultimate Strength (MPa) 0.3 0.4 0.6 8.8 Secant Modulus 1% (MPa) 964 1092 1055 1163 Dev. of Secant Modulus 1% (MPa) 49 11 23 26 Secant Modulus 2% (MPa) 763 842 803 893 Dev. of Secant Modulus 2% (MPa) 19 6 9 10 Young's Modulus (MPa) 1499.9 966 - Dev. of Young's Modulus (MPa) 236.2 91 - Flexural Properties (Plates) Elastic Modulus Secant1% (MPa) 945 1077 978 1092 Dev. Secant Elastic Modulus 1% (MPa) 20 26 29 16 Secant Elastic Modulus 2% (MPa) 805 911 819 927 Dev.Secant Elastic Modulus 2% (MPa) 18 21 27 10 Tangent Elastic Modulus (MPa) 1203 1392 1263 1358 Dev. Tangent Elastic Modulus (MPa) 59 70 27 73 Flexural Strength (MPa) 30.6 33.6 30.5 33.9 Dev. Flexural Strength (MPa) 0.5 0.4 0.8 0.5. Impact Properties (Plates) Izod Impact (nrkg / cm (ft-lb / in)) 0.0566 1.04 0.0539 0.99 0.0528 0.97 0.0506 0.93 Environmental Stress Cracking Resistance ESCR Cond. B at 100% CO - 630 (hrs) 7 7 6 6 Miscellaneous VICAT Softening Point (°C) - Plate 123.9 125.2 - Heat Deflection Temperature (°C) at 155.5 kPa (66 PSI) 67 - - IVIA / a / ¿U¿ I / UU / UO O TABLE 4 - CONTINUED Plate Properties Example No. 3 3* 4 4* 5 5* Tensile Properties (Plates) Elongation at Yield (%) 10 9 10 9 10 9 Dev. Elongation at Yield (%) 0.1 0.3 0.1 0.1 0.1 0.3 Strength at Yield (MPa) 28.8 29.9 28.5 30.9 29.6 30.4 Dev. Strength at Yield (MPa) 0.3 0.6 0.2 0.2 0.2 0.2 Ultimate Elongation (%) 213 652 535 1377 118 775 Dev. Ultimate Elongation (%) 159 672 412 70 87 656 Ultimate Strength (MPa) 18.9 13.9 15.7 19.9 19.3 14.2 Dev. Ultimate Strength (MPa) 7.2 3 1 2.1 8.1 1.3 Secant Modulus 1% (MPa) 1226.8 1296 1219 1418 1266 1371 Dev. Secant Modulus 1% (MPa) 56 122 39 17 54 33 Secant Modulus 2% (MPa) 959 1002 944 1071 990 1045 Dev. Secant Modulus 2% (MPa) 26 59 16 6 20 6 100 Young's Modulus (MPa) 1594.6 1633.1 313.3 Dev. Young's Modulus (MPa) Flexural Properties (Plates) Secant Elastic Modulus 1% (MPa) 1262 1369 1250 1455 1259 1258 Dev. Secant Elastic Modulus 1% (MPa) 30 30 16 44 39 22 Secant Elastic Modulus 2% (MPa) 1063 1143 1060 1214 1065 1051 Dev. Secant Elastic Modulus 2% (MPa) 26 9 12 35 35 20 Tangent Elastic Modulus (MPa) 1493 1664 1456 1747 1471 1531 Dev. Tangent Elastic Modulus (MPa) 65 153 52 32 86 39 Flexural Strength (MPa) 38 38.8 37.8 42.2 38.1 35.9 Dev. Flexural Strength (MPa) 0.6 0.3 0.3 0.3 0.9 0.6 Impact Properties (plates) Izod Impact m-kg / cm (ft-lb / in) 0.0435 (0.80) 0.0408 (0.75) 0.0479 (0.88) 0.0441 (0.81) 0.0408 (0.75) 0.0386 (0.71) Environmental Stress Cracking Resistance ESCRCond. Ba100%CO-630 (hrs) 1 2 0 Various VICAT Softening Point (°C) - Plate 127.5 127 127.6 Heat Deflection Temperature (°C) at 155.05 kPa (66 PSI) 78.3 79.3 79.9 As can be seen from the data in Table 4, the plates prepared from the compositions of 101 inventive copolymers of Examples 1 and 2 had ESCR values ​​which were superior (in this case, higher) than for the plates prepared from the comparative copolymer compositions of Examples 3-5. Alternatively, Figure 5 shows that the inventive core copolymer compositions provide an improved balance of ESCR and OTR properties relative to the comparative core copolymer compositions. As can be seen from the data in Table 4, plates made from the inventive core copolymer compositions (Examples 1* and 2*) had notched Izod impact strengths that were higher than plates made from the comparative core copolymer compositions (Examples 3*-5*). Alternatively, Figure 6 shows that the inventive core copolymer compositions provide an improved balance of impact strength (notched Izod) and OTR properties relative to the comparative core copolymer compositions. Method for manufacturing compression molded films A Wabash MPI Wabash G304 laboratory scale compression molding press was used to prepare compression molded film from the inventive and comparative polyethylene compositions. A metal frame of the required dimensions and thickness was filled with a measured amount of resin (e.g., pellets of a composition 102 polyethylene) and placed between two polished metal plates. The measured amount of polymer used was sufficient to obtain the desired film thickness. Polyester (Mylar) sheets were used on top of the metal backing plates to prevent the resin from sticking to the metal plates. This assembly with the resin was loaded into the compression press and preheated to 200°C under low pressure (e.g., 21482.68 kg / m2 (2 imperial tons or 4400 lb per square foot)) for five minutes. The plates were closed and high pressure (e.g., 301099.31 kg / m2 (28 imperial tons or 61670 lb per square foot)) was applied for another five minutes. After that, the press was cooled to approximately 45°C at a rate of approximately 15°C per minute. At the end of the cycle, the assembly was removed from the frame, disassembled, and the film (or plate) was separated from the frame.Subsequent tests were performed at least 48 hours after the compression molding time. Determination of the Oxygen Transmission Rate (OTR) of a Compression Molded Film Using a Masking Method The oxygen transmission rate (OTR) of the compression molded film was evaluated using an OX-TRAN®2 / 20 instrument manufactured by MOCON Inc, Minneapolis, Minnesota, USA using a version of ASTM F1249-90. The instrument 103 had two test cells (A and B), and each film sample was tested in duplicate. The reported OTR result was the average of the results from these two test cells (A and B). Testing was conducted at a temperature of 23°C and a relative humidity of 0%. Typically, the film sample area used for OTR testing was 100 cm2. However, for barrier testing of films where there is a limited number of samples, a foil mask is used to reduce the test area. By employing the mask, the test area was reduced to 5 cm2. The foil mask had an adhesive on one side to which the sample was bonded. A second foil was then coupled to the first to ensure a leak-free seal. The carrier gas used was 2% hydrogen gas in a nitrogen gas balance, and the test gas was ultrahigh purity oxygen.The OTR of the compression-molded films was tested at the corresponding film thickness obtained from the compression molding process. However, for the purpose of comparing different samples, the resulting OTR values ​​were normalized to a film thickness of 25.4 µm (1 mil). Determination of Water Vapor Transmission Rate (WVTR) of a Compression Molded Film Using a Masking Method The water vapor transmission rate (WVTR) of the compression molded film was tested using a 104 PERMATRAN® 3 / 34 instrument manufactured by MOGON Inc, Minneapolis, Minnesota, USA using a version of ASTM D3985. The instrument had two test cells (A and B) and each film sample was tested in duplicate. The reported WVTR result was the average of the results from these two test cells (A and B). The test is conducted at a temperature of 37.8°C and a relative humidity of 100%. Typically, the film sample area used for WVTR testing was 50 cm2. However, for barrier testing of films where a limited amount of sample was available, a foil mask was used to reduce the test area. When the mask was used, the test area was reduced to 5 cm2. The foil mask has adhesive on one side to which the sample was bonded. A second foil mask was then coupled to the first to ensure a leak-free seal.The carrier gas used was ultra-high purity nitrogen, and the test gas was water vapor at 100% relative humidity. The WVTR of the compression-molded films was evaluated using the corresponding film thickness obtained from the compression molding process. However, for the purpose of comparing different samples, the resulting WVTR values ​​were normalized to a film thickness of 25.4 µm (1 mil). The barrier properties (OTR and WVTR) of pressed films made from polyethylene compositions 105 comparative and inventive features are provided in Table 5. TABLE 5 OTR and WVTR Properties of Cast Films by Compression Example No. 1 Γ (Inventive) 2 2* (Inventive) WVTR - thickness (pm (mil)) 44.45 (1.75) 58.42 (2.3) 67.31 (2.65) 59.69 (2.35) WVTR g / 645.16 cm2 (100 pg2) / day (relative humidity = 100%, 37.8°C, atm) 0.1765 0.1285 0.1761 0.0940 WVTR in g / 645.16 cm2 (100 pg2) / day normalized thickness (25.4 pm (1 mil)) 0.3089 0.2956 0.4667 0.2209 WVTR property improvements after nucleation 4.3% 52.7% OTR - thickness (25.4 µm (mil)) 1.75 2.3 2.65 2.35 OTR in cm3 / 645.16 cm2 (100 µg2) / day (relative humidity = 0%, 23°C, atm) 91.08 50.82 8 8.55 40.92 OTR in cm3 / 645.16 cm2 (100 µg2) / day normalized thickness (25.4 µm (1 mil)) 159.3900 116.89 234.6575 96.16 OTR property improvement after nucleation. 26.7% 59.0% TABLE 5 - CONTINUED OTR and WVTR Properties of Compression Molded Films Example No. 3 3* 4 4* 5 5* WVTR - thickness (25.4 µm (1 mil)) 2.9 2.4 1.7 2.1 2.85 1.85 WVTR g / 645.16 cm2 (100 µg2) / day (relative humidity = 100%, 37.8°C, atm) 0.1279 0.0949 0.1706 0.0965 0.0822 0.1109 106 WVTR in g / 645.16 cm2 (100 pg2) / day - normalized thickness (25.4 pm (1 mil)) 0.3709 0.2278 0.2900 0.2027 0.2343 0.2052 Improvement in WVTR property after nucleation -38.59% -30.13% -12.42% OTR - thickness (mil) 2.9 2.4 1.7 2.1 2.85 1.85 OTR in cm3 / 645.16 cm2 (100 pg2) / day (relative humidity = 0%, 23°C, atm) 54.23 31.22 99.21 40.16 47.61 49.79 OTR in cm3 / 645.16 cm2 (100 pg2) / day - normalized thickness (25.4 pm (1 mil)) 157.2670 74.93 168.6570 84.34 135.6885 92.11 Improvement of OTR property after nucleation 52.4% 50.0% 32.1% As can be seen from the data in Table 5, as well as Figures 2 and 3, a film produced from an inventive nucleated copolymer composition (Example 2*) had OTR and WVTR values ​​that were comparable to films made from the comparative copolymer compositions when similarly nucleated (Examples 3*, 4*, and 5*), even though the inventive nucleated composition (Example 2*) had a much lower density. 107 Method of Manufacturing a Closure by Injection Molding Nucleated versions of the inventive polyethylene copolymer compositions, as well as comparative resins, were processed into closures using an injection molding process. A Sumitomo injection molding machine and a 2.15 gram PCO 1881 carbonated soft drink (CSD) closure mold (plastic only closure) were used to prepare the closures of the present invention. A Sumitomo injection molding machine (model SE75EV C250M) having a screw diameter of 28 mm was used. The 4-cavity CSD closure mold was manufactured by Zmoulds (Austria). The closure design for the 2.15 gram PCO 1881 CSD was developed by Universal Closures Ltd. (UK).During closure manufacturing, four closure parameters—cap top diameter, orifice seal diameter, tamper-evident band diameter, and overall cap height—were measured and ensured to be within quality control specifications. A voluntary standard test method from the International Society of Beverage Technologists (ISBT) was used to determine closure dimensions. The test involved selecting a mold cavity and measuring at least five closures produced from that cavity. At least 14 measurements were obtained. 108 dimensional measurements of fasteners that were aged for at least 1 week from the date of production. Fastener dimension measurements were made using a Vision Engineering Swift Duo dual optical and video measurement system. All measurements were taken at 10x magnification using METLOGIX® M video measurement system software (see METLOGIX M3: Vision Computer Software Digital Field Comparator, User Guide). The closures were formed by injection molding and the injection molding processing conditions are provided in Table 6. TABLE 6 Injection Molding Processing Conditions Example No. 1* (Inv.) 2* (Inv.) 3* 4* 5* No. of Closures 1 2 3 4 5 Additives (Color & Formulation) Natural Natural Natural Natural Natural Part Weight (g) 8.60 8.60 8.60 8.6 8.6 Injection Speed ​​(mm / s) 45 45 45 45 45 Cycle Time (s) 4.49 4.07 4.41 4.36 4.35 Filling Time (s) 0.673 0.662 0.684 0.651 0.640 Dosing Time (s) 1.71 1.715 1.68 1.706 1.64 Minimum Cushion (mm) 9.75 9.75 9.79 9.756 9.76 Pressure Filling Peak (MPa (psi)) 74.284 (10774) 73.69 (10688) 69.24 (10043) 69.85 (10132) 58.14 (8433) 109 Maximum Total Pressure (MPa (PS¡)) 74.38 10789 73.81 10706 69.64 10101 69.98 10151 58.24 8447 End Held Position (mm) 13.56 12.76 15.00 12.63 12.77 Clamping Force (ton) 20 20 19 20 20 Initial Filling Position (mm) 40.01 39.49 40.51 39.00 3 8.51 Dosing Back Pressure (MPa (psi)) 5.819 844 5.819 844 5.798 841 5.805 842 5.791 840 Package Pressure (MPa (psi)) 74.30 10777 73.71 10692 69.41 10067 69.91 10140 58.15 8434 Fill Time 1 (s) 0.672 0.664 0.688 0.648 0.640 Temperature Zone 1 (°C) 180 180 180 180 180 Temperature Zone 2 (°C) 185 185 185 185 185 Temperature Zone 3 (°C) 190 190 190 190 190 Temperature Zone 4 (°C) 200 200 200 200 200 Temperature Zone 5 (°C) 200 200 200 200 200 Stationary mold temperature (°C) 10 10 10 10 10 Oxygen Transmission Rate (OTR) of an Injection Molded Closure To measure the oxygen transmission rate through a closure, ASTM D3985 (Standard Test Method for Oxygen Gas Transmission Rate Through Plastic Films and Sheets Using a Coulometric Sensor) was adapted as described below. First, the tamper-evident strip was removed from the closure. The bottom edge of the closure was then lightly sanded with sandpaper (for better 110 adhesion to epoxy resin) and then the closure was bonded with epoxy resin (using DEVCON® 2 epoxy part) to a test plate so that it covered an outlet tube (for sweep gas) and the inlet tube for N2 introduction. The epoxy was left to dry overnight. One of the two gas tubes protruding into the closure interior carried nitrogen gas flowing into the closure interior (nitrogen feed line), while the other carried sweep gas (e.g., nitrogen plus permeate from the closure’s surrounding atmosphere) out of the closure interior and into a detector. If any oxygen was present in the atmosphere permeating the closure walls, it was detected as a component within the N2 exiting the closure interior as sweep gas.The plate / closure / tube apparatus is connected to an OX-TRAN low-end instrument (PERMATRAN-C® Model 2 / 21 MD) with the test plate placed in an environmental chamber controlled to a temperature of 23°C. A baseline measurement for atmospheric oxygen detection was also taken using an impermeable aluminum foil (in parallel with the closure) for direct permeability comparison. The oxygen permeability of the closure is reported as the average oxygen transmission rate in units of cm3 / closure / day. The oxygen barrier properties of closures 111 injection moldings produced from comparative and inventive polyethylene compositions, all of which have been nucleated, are provided in Table 7. TABLE 7 Example No. No. of Closures Average OTR (cm3 / closure / day) Test Gas 1* (Inventive) 1 0.0027 ambient air (20.9% oxygen) 2* (Inventive) 2 0.0026 ambient air (20.9% oxygen) 3* 3 0.0026 ambient air (20.9% oxygen) 4* 4 0.0024 ambient air (20.9% oxygen) 5* 5 0.0025 ambient air (20.9% oxygen) As can be seen from the data in Table 7 as well as Figure 4, closures produced from the inventive nucleated copolymer compositions (Examples 1* and 2*) had OTR values ​​that were comparable to closures produced from comparative copolymer compositions (Examples 3*, 4* and 5*) which were similarly nucleated, even though the inventive compositions are of a much lower density. Thus, the nucleated compositions of the present invention have a particularly good balance of impact strength (Izod) values, DESC values ​​and oxygen transmission rates (in a closure), making them particularly suitable for compression molded or molded closure applications. 112 injection molded products, where barrier properties may be desirable. Furthermore, the use of a lower density polyethylene copolymer composition as described herein may have advantages in the manufacture of articles which may benefit from good barrier properties, such as for example a cap or closure for a bottle, container or the like, or an assembly for a bag or the like. INDUSTRIAL APPLICABILITY A dual-reactor solution polymerization process provides polyethylene compositions with a balance of properties, such as barrier properties, toughness properties, and environmental resistance. The polyethylene compositions can be useful in end-use applications such as bottle closures or films that have barrier properties. It is noted that in relation to this date, the best method known to the applicant to put the aforementioned invention into practice is the one that is clear from the present description of the invention.

Claims

1. A polyethylene copolymer composition characterized in that it comprises: (1) 10 to 70% by weight of a first ethylene copolymer having a melting index I2, from 0.1 to 10 g / 10 min; a molecular weight distribution Mw / Mn of less than 3.0; and a density from 0.900 to 0.946 g / cm3; and (2) 90 to 30% by weight of a second ethylene copolymer having a melting index I2, from 25 to 1500 g / 10 min; a molecular weight distribution M„ / Mn of less than 3.0; and a density higher than the density of the first ethylene copolymer, but less than 0.970 g / cm3; wherein the density of the second ethylene copolymer is less than 0.037 g / cm3 higher than the density of the first ethylene copolymer; the ratio (SCB1 / SCB2) of the number of short-chain branches per thousand carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per thousand carbon atoms in the second ethylene copolymer (SCB2) is greater than 1.0; and wherein the polyethylene copolymer composition has a molecular weight distribution Mw / Mn, from 1.8 to 7.0; a density less than 0.949 g / cm3; a high load melt index 114 I21, of at least 150 g / 10 min; an average molecular weight Z Mz of less than 200,000; a melt flux ratio I21 / I2, from 20 to 50; a strain exponent less than 1.40; and an ESCR Condition B (100% Igepal) of at least 3.5 hours; and wherein the polyethylene copolymer composition further comprises a nucleating agent.

2. The polyethylene copolymer composition according to claim 1, characterized in that it has an ESCR Condition B (100% Igepal) from 3.5 to 15 hours.

3. The polyethylene copolymer composition according to claim 1, characterized in that it has a melt index I2, from more than 5.0 to less than 20.0 g / 10 min.

4. The polyethylene copolymer composition according to claim 1, characterized in that the density of the second ethylene copolymer is less than 0.030 g / cm3 higher than the density of the first ethylene copolymer.

5. The polyethylene copolymer composition according to claim 1, characterized in that the first ethylene copolymer has a melting index I2, from 0.1 to 5.0 g / 10 min.

6. The polyethylene copolymer composition 115 according to claim 1, characterized in that the second ethylene copolymer has a melting index I2, from 25 to 500 g / 10 min.

7. The polyethylene copolymer composition according to claim 1, characterized in that it has a high load melt index I21 of at least 200.

8. The polyethylene copolymer composition according to claim 1, characterized in that it has a high load melt index I21, from 200 to 500 g / 10 min.

9. The polyethylene copolymer composition according to claim 1, characterized in that it has a bimodal molecular weight distribution as determined by gel permeation chromatography.

10. The polyethylene copolymer composition according to claim 1, characterized in that the ratio (SCB1 / SCB2) of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer (SCB1) to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB2) is at least 2.

0.

11. The polyethylene copolymer composition according to claim 1, characterized in that it has a molecular weight distribution Mw / Mn, from 2.0 to 116 4.

0.

12. The polyethylene copolymer composition according to claim 1, characterized in that the first ethylene copolymer has a density from 0.920 to 0.940 g / cm3.

13. The polyethylene copolymer composition according to claim 1, characterized in that the second ethylene copolymer has a density of less than 0.965 g / cm3.

14. The polyethylene copolymer composition according to claim 1, characterized in that the second ethylene copolymer has a density from 0.946 to 0.963 g / cm3.

15. The polyethylene copolymer composition according to claim 1, characterized in that it has a density from 0.939 to less than 0.949 g / cm3.

16. The polyethylene copolymer composition according to claim 1, characterized in that it has no long chain branches.

17. The polyethylene copolymer composition according to claim 1, characterized in that it has a composition distribution amplitude index CDBI(50) greater than 65% by weight.

18. The polyethylene copolymer composition according to claim 1, characterized in that ccr? nn / Lznz / E / YiA 117 comprises: from 20 to 55% by weight of the first ethylene copolymer; and from 80 to 45% by weight of the second ethylene copolymer.

19. The polyethylene copolymer composition according to claim 1, characterized in that the first and second ethylene copolymers are ethylene and 1-octene copolymers.

20. The polyethylene copolymer composition according to claim 1, characterized in that the nucleating agent is present in from 20 to 4000 parts per million based on the combined weight of the first ethylene copolymer and the second ethylene copolymer.

21. The polyethylene copolymer composition according to claim 1, characterized in that the nucleating agent is a salt of a dicarboxylic acid compound.

22. The polyethylene copolymer composition according to claim 1, characterized in that when produced in a CSD PCO 1881 closure, it has an OTR of less than 0.0030 cm3 / closure / day.

23. A film characterized in that it comprises the polyethylene copolymer composition according to claim 1 and has a standardized OTR of < 120cm3 / 645.16 cm2 (100 pg2) / day.

24. A film characterized in that it comprises the polyethylene copolymer 118 according to claim 1 and has a standardized WVTR of < 0.320 g / 645.16 cm2 (100 pg2) / day.

25. A bottle closure, characterized in that it comprises a polyethylene copolymer comprising: (1) 10 to 70% by weight of a first ethylene copolymer having a melting index I2, from 0.1 to 10 g / 10 min; a molecular weight distribution Mw / Mn less than 3.0; and a density from 0.900 to 0.946 g / cm3; and (2) 90 to 30% by weight of a second ethylene copolymer having a melting index I2, from 25 to 1500 g / 10 min; a molecular weight distribution Mw / Mn less than 3.0; and a density higher than the density of the first ethylene copolymer, but less than 0.970 g / cm3; wherein the density of the second ethylene copolymer is less than 0.037 g / cm3 higher than the density of the first ethylene copolymer; The ratio (SCB1 / SCB2) of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer (SCB1) to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB2) is greater than 1.0; and wherein the polyethylene copolymer composition has a molecular weight distribution Mw / Mn, from 1.8 to 7.0; a density of less than 0.949 g / cm3; a high load melt index I21, of at least 150 g / 10 min; an average molecular weight Z Mz of less than 200,000; a melt flux ratio I21 / I2, from 20 to 50; a strain exponent less than 1.40; and an ESCR Condition B (100% Igepal) of at least 3.5 hours; and wherein the polyethylene copolymer composition further comprises a nucleating agent.

26. A film, characterized in that it comprises a polyethylene copolymer composition comprising: (1) 10 to 70% by weight of a first ethylene copolymer having a melt index I2, from 0.1 to 10 g / 10 min; a molecular weight distribution Mw / Mn of less than 3.0; and a density from 0.900 to 0.946 g / cm3; and (2) 90 to 30% by weight of a second ethylene copolymer having a melt index I2, from 25 to 1500 g / 10 min; a molecular weight distribution Mw / Mn of less than 3.0; and a density higher than the density of the first ethylene copolymer, but less than 0.970 g / cm3; wherein the density of the second ethylene copolymer is less than 0.037 g / cm3 higher than the density of the first ethylene copolymer; the ratio (SCB1 / SCB2) of the number of short-chain branches per thousand carbon atoms in the first ethylene copolymer (SCB1) to the number of short-chain branches per thousand carbon atoms in the second ethylene copolymer (SCB2) is greater than 1.0; and wherein the polyethylene copolymer composition has a molecular weight distribution Mw / Mn, from 1.8 to 7.0; a density of less than 0.949 g / cm3; a high-load melt index I21, of at least 150 g / 10 min; an average molecular weight Z Mz, of less than 200,000; a melt flow ratio I21 / I2, from 20 to 50; a strain exponent less than 1.40; and an ESCR Condition B (100% Igepal) of at least 3.5 hours; and wherein the polyethylene copolymer composition further comprises a nucleating agent.