Ethylene polymer containing a reversible crosslinking agent

Abstract

The present disclosure provides a crosslinkable polymer composition. In one embodiment, the crosslinkable polymer composition comprises an ethylene-based polymer, a free radical initiator, and 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate). The present disclosure provides a crosslinked composition. In one embodiment, the crosslinked composition comprises an ethylene-based polymer and 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate).

Description

Technical Field

[0001] Crosslinked olefin polymers (and in particular crosslinked ethylene polymers) are well known in numerous applications due to their excellent mechanical properties, high thermal stability, and outstanding chemical resistance. Unfortunately, crosslinked ethylene polymers (also known as thermosetting polymers) cannot be reprocessed and / or recycled due to the presence of a permanent crosslinked network within the ethylene polymer. Thus, the use of crosslinked ethylene polymers is associated with attendant environmental and sustainability concerns.

[0002] The ability to reprocess and / or recycle crosslinked ethylene polymers has been a longstanding challenge. Accordingly, in the art, there is a recognized need for crosslinked olefin polymers (and in particular crosslinked ethylene polymers) that are reprocessable and / or recyclable.

Summary of the Invention

[0003] The present disclosure provides a crosslinkable polymer composition. In one embodiment, the crosslinkable polymer composition comprises an ethylene polymer, a free radical initiator, and 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate).

[0004] The present disclosure provides a crosslinked composition. In one embodiment, the crosslinked composition comprises an ethylene polymer and 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate).

[0005] Definitions All references to the Periodic Table of the Elements in this specification are intended to refer to the Periodic Table copyrighted and published in 2003 by CRC Press, Inc. Further, any reference to a group is intended to refer to the group reflected in that Periodic Table of the Elements using the IUPAC system for numbering groups. Unless otherwise stated, unless implicit from the context, or unless not customary in the art, all parts and percentages are by weight. For purposes of U.S. patent practice, the contents of any patent, patent application, or publication referenced herein are hereby incorporated by reference in their entirety (or their equivalent U.S. version is so incorporated by reference).

[0006] The numerical ranges disclosed in this specification include all values (including the boundary values) from the lower limit value to the upper limit value. In the case of a range containing explicit values (for example, a range of 1 or 2 or 3 to 5 or 6 or 7), any sub-range between the two explicit values is included (for example, the above range of 1 to 7 includes sub-ranges such as 1 to 2, 2 to 6, 5 to 7, 3 to 7, 5 to 6, etc.).

[0007] Unless otherwise stated, unless implicit from the context, or unless not customary in the art, all parts and percentages are by weight and all test methods are the latest as of the filing date of this disclosure.

[0008] As used herein, the term "composition" refers to a mixture of materials that includes the composition, as well as reaction products and decomposition products formed from the materials of the composition.

[0009] The terms "comprising", "including", "having", and their derivatives are not intended to exclude the presence of any additional constituent, step, or procedure, whether or not specifically disclosed. To avoid any doubt, all compositions claimed through the use of the term "comprising" may, unless inconsistent therewith, contain any additional additives, adjuvants, or compounds, whether polymeric or otherwise. In contrast, the term "consisting essentially of" excludes any other constituent, step, or procedure from the scope of any subsequent description, except for those that are not essential to the operability. The term "consisting of" excludes any constituent, step, or procedure not specifically depicted or listed.

[0010] "Ethylene-based polymer" is a polymer that contains more than 50 mol% of polymerized ethylene monomer (based on the total amount of polymerizable monomers) and may optionally contain at least one comonomer. Ethylene-based polymers include ethylene homopolymers and ethylene copolymers (meaning units derived from ethylene and one or more comonomers). The terms "ethylene-based polymer" and "polyethylene" may be used synonymously. Non-limiting examples of ethylene-based polymers (polyethylene) include low density polyethylene (LDPE) and linear polyethylene. Non-limiting examples of linear polyethylene include linear low density polyethylene (LLDPE), ultra low density polyethylene (ULDPE), very low density polyethylene (VLDPE), multi-component ethylene copolymers (EPE), ethylene / α-olefin multi-block copolymers (also known as olefin block copolymers (OBC)), substantially linear or linear plastomers / elastomers, and high density polyethylene (HDPE). Generally, polyethylene can be produced using heterogeneous catalyst systems such as Ziegler-Natta catalysts, Group 4 transition metals and metallocenes, non-metallocene metal centers, homogeneous catalyst systems containing ligand structures such as heteroaryls, heterovalent aryloxyethers, phosphine imines, etc., and others, in gas phase, fluidized bed reactor, liquid phase slurry process reactor, or liquid phase solution process reactor. Combinations of heterogeneous and / or homogeneous catalysts can also be used in either single reactor or dual reactor configurations.

[0011] "Ethylene plastomer / elastomer" means units derived from ethylene and at least one C3-C 10It is a substantially linear or linear ethylene / α-olefin copolymer containing a uniform short-chain branching distribution comprising units derived from an α-olefin comonomer. The ethylene plastomer / elastomer has a density of 0.870 g / cc to 0.917 g / cc. Non-limiting examples of ethylene plastomers / elastomers include AFFINITY™ plastomers and elastomers (available from The Dow Chemical Company), EXACT™ plastomers (available from ExxonMobil Chemical), Tafmer™ (available from Mitsui), Nexlene™ (available from SK Chemicals Co.), and Lucene™ (available from LG Chem Ltd.).

[0012] "High density polyethylene" (or "HDPE") is an ethylene homopolymer or at least one C4-C 10 α-olefin comonomer or C 4- It is an ethylene / α-olefin copolymer containing a C8α-olefin comonomer and has a density of 0.940 g / cc, or 0.945 g / cc, or 0.950 g / cc, or 0.953 g / cc to 0.955 g / cc, or 0.960 g / cc, or 0.965 g / cc, or 0.970 g / cc, or 0.975 g / cc, or 0.980 g / cc. HDPE may be a unimodal copolymer or a multimodal copolymer. A "unimodal ethylene copolymer" is an ethylene / C4-C 10 α-olefin copolymer having one distinct peak in gel permeation chromatography (GPC) showing a molecular weight distribution. A "multimodal ethylene copolymer" is an ethylene / C4-C 10It is an α-olefin copolymer. Examples of multimodality include copolymers having two peaks (bimodality) and copolymers having three or more peaks. Non-limiting examples of HDPE include DOW (trademark) high-density polyethylene (HDPE) resin (commercially available from The Dow Chemical Company), ELITE (trademark) enhanced polyethylene resin (commercially available from The Dow Chemical Company), CONTINUUM (trademark) bimodal polyethylene resin (commercially available from The Dow Chemical Company), LUPOLEN (trademark) (commercially available from LyondellBasell), and HDPE products from Borealis, Ineos, and ExxonMobil.

[0013] "Linear low-density polyethylene (or "LLDPE")" is a linear ethylene / α-olefin copolymer containing units derived from ethylene and units derived from at least one C3-C 10 α-olefin, or C4-C8 α-olefin comonomer, and having a non-uniform short-chain branch distribution. LLDPE is characterized by having little to no long-chain branching, in contrast to conventional LDPE. LLDPE has a density of from 0.910 g / cc to less than 0.940 g / cc. Non-limiting examples of LLDPE include TUFLIN (trademark) linear low-density polyethylene resin (available from The Dow Chemical Company), DOWLEX (trademark) polyethylene resin (available from the Dow Chemical Company), and MARLEX (trademark) polyethylene (available from Chevron Phillips).

[0014] "Low-density polyethylene" (or "LDPE") is an ethylene homopolymer or contains at least one C3-C having a density of 0.915 g / cc to 0.940 g / cc and long-chain branching with a broad MWD. 10It consists of an ethylene / α-olefin copolymer containing α-olefin or C4-C8 α-olefin. LDPE is typically produced by high-pressure free radical polymerization (tubular reactor or autoclave using a free radical initiator). Non-limiting examples of LDPE include MarFlex (trademark) (Chevron Phillips), LUPOLEN (trademark) (LyondellBasell), and LDPE products from Borealis, Ineos, ExxonMobil, etc.

[0015] As used herein, "olefinic polymer" or "polyolefin" is a polymer containing more than 50 mole percent polymerized olefin monomer (based on the total amount of polymerizable monomers) and optionally containing at least one comonomer. Non-limiting examples of olefinic polymers include ethylene-based polymers and propylene-based polymers.

[0016] A "polymer" is a compound prepared by polymerizing monomers, whether of the same or different types, which provides multiple and / or repeating "units" or "structural units" that make up the polymer in a polymerized form. Thus, the general term "polymer" encompasses the term "homopolymer", which is commonly used to refer to a polymer prepared from only one type of monomer, and the term "copolymer", which is commonly used to refer to a polymer prepared from at least two types of monomers. It also includes all forms of copolymers, such as random and block copolymers. The terms "ethylene / α-olefin polymer" and "propylene / α-olefin polymer" refer to the above-mentioned copolymers prepared by polymerizing ethylene or propylene and one or more additional polymerizable α-olefin monomers, respectively. Polymers are often referred to as being "made from" one or more specified monomers, such as being "based on" a specified monomer or monomer type and "containing" a specified monomer content. However, in this context, it should be noted that the term "monomer" is understood to refer to the polymerized residue of the specified monomer and does not refer to non-polymerized species. Generally, polymers herein are referred to as being based on "units" that are the polymerized form of the corresponding monomers.

[0017] Test Methods Density is measured in accordance with ASTM D792, and the results are reported in g / cc at 25°C.

[0018] Differential scanning calorimetry (DSC) was performed using a Mettler Toledo DSC822e differential scanning calorimeter to measure the thermal properties including the peak and end point melting temperatures and crystallinity of the polymer and crosslinked compositions (network polymers). The network materials tested for most polymers are as-synthesized materials prior to compression molding. In the Examples section, IE1 of Polymer 7 (INFUSE™ 9100) was selected to demonstrate thermal property recovery by collecting DSC data after each successive compression molding reuse (up to 3 times) (Table 4). A heating rate of 10 °C / min and a cooling rate of -40 °C / min were applied for all measurements in the temperature range of -60 °C to 160 °C

[0019] Dynamic mechanical analysis (DMA). DMA experiments were performed using a TA Instruments RSA-G2 Solid Analyzer to measure the storage modulus (E’), loss modulus (E”), and damping ratio (tanδ) of the network as a function of temperature and reuse under a nitrogen atmosphere. DMA is operated in tension mode at a frequency of 1 Hz with a vibration strain of 0.03%. Data are collected from room temperature to 160 °C at a heating rate of 3 °C / min.

[0020] High temperature creep test. Samples were compression molded into 0.7 mm thick tensile bars with a bar dimension of 16 mm × 4.5 mm. The bars were clamped in an oven at 130 °C, suspended vertically, and a 60 g weight was suspended from the bottom. The time required for the weight to fall to the oven floor (indicating sample failure) was measured and tabulated. The experimental uncertainty was estimated using the standard deviation of 3 - 4 creep tests.

[0021] (Ethylene polymer) melt index (MI or I2) was measured according to ASTM D 1238 under the conditions of 190 °C / 2.16 kg, and the results are reported in grams per 10 minutes (g / 10 min). I 21It is measured according to ASTM D1238, Condition 190 °C / 21.6 kg and reported in grams per 10 minutes (g / 10 min).

DETAILED DESCRIPTION OF THE INVENTION

[0022] The present disclosure provides a crosslinkable polymer composition. In one embodiment, the crosslinkable polymer composition includes an ethylene-based polymer, a free radical initiator, and 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate).

[0023] A. Ethylene-based polymer The crosslinkable polymer composition includes an ethylene-based polymer. The ethylene-based polymer can be an ethylene homopolymer, an ethylene / C3-C 10 α-olefin copolymer, or an ethylene C4-C8 α-olefin copolymer. The ethylene-based polymer has a melt index (MI) of 0.1 g / 10 min to 100 g / 10 min, or 1 g / 10 min to 100 g / 10 min, or 1 g / 10 min to 50 g / 10 min, or 1 g / 10 min to 25 g / 10 min, or 1 g / 10 min to 10 g / 10 min, or 1 g / 10 min to 5 g / 10 min. Non-limiting examples of suitable ethylene-based polymers include ethylene plastomers / elastomers, high density polyethylene (HDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), ethylene / α-olefin multi-block copolymers, and combinations thereof.

[0024] In one embodiment, the ethylene-based polymer is an ethylene plastomer / elastomer.

[0025] In one embodiment, the ethylene-based polymer is HDPE.

[0026] In one embodiment, the ethylene-based polymer is LLDPE.

[0027] In one embodiment, the ethylene-based polymer is LDPE.

[0028] In one embodiment, the ethylene-based polymer is an ethylene / α-olefin multiblock copolymer. The term "ethylene / α-olefin multiblock copolymer" refers to an ethylene / C4-C8α-olefin multiblock copolymer composed of a polymerization form of ethylene and one copolymerizable C4-C8α-olefin comonomer (and optionally additives), and the polymer is characterized by a plurality of blocks or segments of two polymerization monomer units with different chemical or physical properties, and the blocks are joined (or covalently bonded) in a linear manner. That is to say, the polymer contains chemically distinct units with ends joined to the polymerized ethylenic functional groups. Ethylene / α-olefin multiblock copolymers include block copolymers having two blocks (diblocks) and more than two blocks (multiblocks). The C4-C8α-olefin is selected from butene, hexene, and octene. The ethylene / α-olefin multiblock copolymer does not contain styrene (i.e., styrene-free), and / or vinyl aromatic monomers, and / or conjugated dienes, or alternatively excludes them. When referring to the amount of "ethylene" or "comonomer" in the copolymer, this is understood to refer to its polymerization unit. In some embodiments, the ethylene / α-olefin multiblock copolymer has the following formula: (AB) ncan be represented by the formula, where n is at least 1, preferably an integer greater than 1, for example, 2, 3, 4, 5, 10, 15, 20, 30, 40, 50, 60, 70, 80, 90, 100, or more; "A" represents a hard block or segment, and "B" represents a soft block or segment. A and B are linked or covalently bonded in a substantially linear manner, or in a linear pattern, as opposed to a substantially branched or substantially star-shaped manner. In other embodiments, the A blocks and B blocks are randomly distributed along the polymer chain. In other words, the block copolymer typically does not have the following structure: AAA-AA-BBB-BB. In one embodiment, the ethylene / α-olefin multiblock copolymer does not have a third type of block containing different comonomers. In another embodiment, each of block A and block B has monomers or comonomers randomly distributed substantially within the block. In other words, neither block A nor block B contains two or more subsegments (or subblocks) of distinct compositions, such as a tip segment having a composition substantially different from the remaining blocks.

[0029] In one embodiment, ethylene constitutes more than half of the molar fraction of the total ethylene / α-olefin multiblock copolymer, that is, ethylene constitutes at least 50% by weight of the total ethylene / α-olefin multiblock copolymer. More preferably, ethylene comprises at least 60% by weight, at least 70% by weight, or at least 80% by weight, along with substantially the remaining portion of the total ethylene / α-olefin multiblock copolymer containing C4-C8 α-olefin comonomers. In one embodiment, the ethylene / α-olefin multiblock copolymer contains 50% to 90% by weight of ethylene, or 60% to 85% by weight of ethylene, or 65% to 80% by weight of ethylene. In the case of many ethylene / octene multiblock copolymers, the composition comprises an ethylene content of more than 80% by weight of the total ethylene / octene multiblock copolymer and an octene content of 10% to 15% or 15% to 20% by weight of the total multiblock copolymer.

[0030] Ethylene / α-olefin multiblock copolymers contain various amounts of "hard" segments and "soft" segments. The "hard" segments are blocks of polymerized units in which ethylene is present in an amount of more than 90 wt%, or 95 wt%, or more than 95 wt%, or more than 98 wt%, up to a maximum of 100 wt% based on the weight of the polymer. In other words, the comonomer content (content of monomers other than ethylene) in the hard segments is less than 10 wt%, or 5 wt%, or less than 5 wt%, or less than 2 wt% based on the weight of the polymer, and can be as low as zero. In some embodiments, the hard segments contain all or substantially all of the units derived from ethylene. The "soft" segments are blocks of polymerized units in which the comonomer content (content of monomers other than ethylene) is more than 5 wt%, or more than 8 wt%, more than 10 wt%, or more than 15 wt% based on the weight of the polymer. In one embodiment, the comonomer content in the soft segments is more than 20 wt%, more than 25 wt%, more than 30 wt%, more than 35 wt%, more than 40 wt%, more than 45 wt%, more than 50 wt%, or more than 60 wt%, and can be up to 100 wt%.

[0031] The soft segment may be present in the ethylene / α-olefin multiblock copolymer in an amount of 1 wt% to 99 wt% of the total weight of the ethylene / α-olefin multiblock copolymer, or 5 wt% to 95 wt%, 10 wt% to 90 wt%, 15 wt% to 85 wt%, 20 wt% to 80 wt%, 25 wt% to 75 wt%, 30 wt% to 70 wt%, 35 wt% to 65 wt%, 40 wt% to 60 wt%, or 45 wt% to 55 wt% of the total weight of the ethylene / α-olefin multiblock copolymer. Conversely, the hard segment may be present in a similar range. The weight percentages of the soft segment and the hard segment can be calculated based on data obtained from DSC or NMR. Such methods and calculations are disclosed, for example, in U.S. Patent No. 7,608,668, entitled "Ethylene / α-Olefin Block Inter-Polymers," filed on March 15, 2006, in the names of Colin L.P. Shan, Lonnie Hazlitt, et al., and assigned to Dow Global Technologies Inc., the disclosure of which is hereby incorporated by reference in its entirety. In particular, the weight percentages and comonomer contents of the hard segment and the soft segment may be determined as described in columns 57 to 63 of U.S. Patent No. 7,608,668.

[0032] An ethylene / α-olefin multiblock copolymer comprises two or more chemically distinct regions or segments (referred to as "blocks") joined (or covalently bonded) in a linear fashion, i.e., it contains chemically distinguishable units that are joined end-to-end rather than pendant or grafted to the polymerized ethylenic functionality. In one embodiment, the blocks differ in the amount or type of comonomer incorporated, density, amount of crystallinity, the size of the crystallites that may result from a polymer of such composition, the type or degree of stereoregularity (isotactic or syndiotactic), regioregularity or regiomrandomness, the amount of branching (including long-chain branching or hyperbranching), homogeneity, or any other chemical or physical property. Compared to prior art block interpolymers, including interpolymers produced by continuous monomer addition, metallocene catalysts, or anionic polymerization techniques, the ethylene / α-olefin multiblock copolymers of the present invention are, in one embodiment, characterized by a unique distribution of both the polymer polydispersity (PDI or Mw / Mn or MWD), the polydisperse block length distribution, and / or the polydisperse block number distribution due to the effect of the shuttle agent in combination with the multiple catalysts used in their preparation.

[0033] In one embodiment, the ethylene / α-olefin multiblock copolymer is produced in a continuous process and has a polydispersity index (Mw / Mn) of from 1.7 to 3.5, or from 1.8 to 3, or from 1.8 to 2.5, or from 1.8 to 2.2. When produced in a batch or semi-batch process, the ethylene / α-olefin multiblock copolymer has an Mw / Mn of from 1.0 to 3.5, or from 1.3 to 3, or from 1.4 to 2.5, or from 1.4 to 2.

[0034] Furthermore, the ethylene / α-olefin multiblock copolymer has a PDI (or Mw / Mn) that conforms to the Schultz-Flory distribution rather than the Poisson distribution. This ethylene / α-olefin multiblock copolymer has both a polydisperse block distribution and a polydisperse distribution of block sizes. Thereby, a polymer product having improved distinguishable physical properties is formed. The theoretical advantages of the polydisperse block distribution have already been modeled and considered in Potemkin, Physical Review E (1998) 57(6), pp. 6902-6912, and Dobrynin, J. Chem. Phys. (1997) 107(21), pp9234-9238.

[0035] In one embodiment, this ethylene / α-olefin multiblock copolymer has a most probable distribution of block lengths.

[0036] In a further embodiment, the ethylene / α-olefin multiblock copolymer of the present disclosure, particularly that made in a continuous solution polymerization reactor, has a most probable distribution of block lengths. In one embodiment of the present disclosure, the ethylene / α-olefin multiblock copolymer is defined as having: (A) an Mw / Mn of from about 1.7 to about 3.5, at least one melting point Tm (in degrees Celsius), and a density d (in grams per cubic centimeter), where the numerical values of Tm and d are related by: Tm > -2002.9 + 4538.5(d) - 2422.2(d) 2 corresponding; and / or (B) characterized by an Mw / Mn of from about 1.7 to about 3.5, and a heat of fusion DH in units of J / g, and a delta amount DT in degrees Celsius defined as the temperature difference between the highest DSC peak and the highest crystallization analysis fraction ("CRYSTAF") peak, where the numerical values of DT and DH have the following relationship: when DH is greater than zero and at most 130 J / g, DT > -0.1299DH + 62.81, when DH is greater than 130 J / g, DT ≧ 48 °C The CRYSTAF peak is determined using at least 5 percent of the cumulative polymer. If less than 5 percent of the polymer has a resolvable CRYSTAF peak, the CRYSTAF temperature is 30 °C; and / or (C) having 300 percent strain and elastic recovery Re (percent) in one cycle measured on a compression molded film of the ethylene / α-olefin interpolymer, having a density d (grams per cubic centimeter), and when the ethylene / α-olefin interpolymer is substantially free of a crosslinked phase, the numerical values of Re and d are related by: Re > 1481 - 1629(d) such that; and / or (D) having a molecular fraction eluting at 40 °C to 130 °C when fractionated using TREF, the fraction having a comonomer molar content at least 5 percent higher than an equivalent random ethylene interpolymer fraction eluting between the same temperatures, the equivalent random ethylene interpolymer having the same comonomer and having a melt index, density, and comonomer molar content (based on the total polymer) within 10 percent of the ethylene / α-olefin interpolymer; and / or (E) having a storage modulus G'(25 °C) at 25 °C and a storage modulus G'(100 °C) at 100 °C, the ratio of G'(25 °C) to G'(100 °C) being in the range of about 1:1 to about 9:1.

[0037] The ethylene / α-olefin multiblock copolymer may also have: (F) a molecular fraction eluting at 40 °C to 130 °C when fractionated using TREF, the fraction having a block index of at least 0.5 and at most 1 and a molecular weight distribution Mw / Mn greater than 1.3; and / or (G) an average block index greater than zero and at most 1.0 and a molecular weight distribution Mw / Mn greater than 1.3.

[0038] It is understood that the ethylene / α-olefin multiblock copolymer may have one, several, all, or any combination of properties (A) to (G). The block index can be determined as detailed in U.S. Patent No. 7,608,668, which is incorporated herein by reference for that purpose. The analysis methods for determining properties (A) to (G) are disclosed, for example, in columns 31, line 26 to column 35, line 44 of U.S. Patent No. 7,608,668, which is incorporated herein by reference for that purpose.

[0039] In one embodiment, the ethylene / α-olefin multiblock copolymer has hard segments and soft segments, is styrene-free, consists of only (i) ethylene and (ii) a C4-C8 α-olefin or a C8 α-olefin (and any additives), and is defined as having an Mw / Mn of 1.7 to 3.5, at least one melting point Tm (in degrees Celsius), and a density d (in grams per cubic centimeter), and the numerical values of Tm and d correspond to the following relationship: Tm > -2002.9 + 4538.5(d) - 2422.2(d) 2 , wherein the density d is 0.850 g / cc, or 0.860 g / cc, or from 0.870 g / cc to 0.875 g / cc, or 0.877 g / cc, or 0.880 g / cc, or 0.890 g / cc, and the melting point Tm is 110 °C, or 115 °C, or from 120 °C to 125 °C, or 130 °C, or 135 °C.

[0040] In one embodiment, the ethylene / α-olefin multiblock copolymer is an ethylene / 1-octene multiblock copolymer (consisting of only ethylene and octene comonomer) and has one, several, or all of the following properties: (i) an Mw / Mn of 1.7 or 1.8 to 2.2, or 2.5, or 3.5, and / or (ii) a density of from 0.860 g / cc or 0.865 g / cc to 0.870 g / cc, or 0.877 g / cc, or 0.880 g / cc, and / or (iii) A melting point Tm of 115 °C, or 118 °C, or 119 °C, or 120 °C to 120 °C, or 123 °C, or 125 °C, and / or (iv) A melt index (MI) of 0.1 g / 10 min or 0.5 g / 10 min to 1.0 g / 10 min, or 2.0 g / 10 min, or 5 g / 10 min, or 10 g / 10 min, and / or (v) (Based on the total weight of the ethylene / octene multiblock copolymer) 50 to 85 wt% soft segments and 40 to 15 wt% hard segments, and / or (vi) 10 mol%, or 13 mol%, or 14 mol%, or 15 mol% to 16 mol%, or 17 mol%, or 18 mol%, or 19 mol%, or 20 mol% octene in the soft segments, and / or (vii) 0.5 mol%, or 1.0 mol%, or 2.0 mol%, or 3.0 mol% to 4.0 mol%, or 5 mol%, or 6 mol%, or 7 mol%, or 9 mol% octene in the hard segments, and / or (viii) When measured according to ASTM D 1708, an elastic recovery (Re) of 50% or 60% to 70%, or 80%, or 90% at a deformation rate of 300% / min at 21 °C ·1 and / or (ix) The polydispersity distribution of the blocks and the polydispersity distribution of the block sizes (hereinafter referred to as the characteristics (i) to (ix) of the multiblock copolymer).

[0041] In one embodiment, the ethylene / α-olefin multiblock copolymer is an ethylene / octene multiblock copolymer. The ethylene / octene multiblock copolymer is sold under the trade name INFUSE™ available from The Dow Chemical Company (Midland, Michigan, USA).

[0042] The ethylene / α-olefin multiblock copolymer can be produced via a chain shuttling process such as that described in U.S. Patent No. 7,858,706, which is incorporated herein by reference. In particular, suitable chain shuttling agents and related information are listed from line 39, column 16 to line 44, column 19. Suitable catalysts are described from line 45, column 19 to line 19, column 46, and suitable cocatalysts are described from line 20, column 46 to line 28, column 51. The process is described throughout the document, and in particular, from line 29, column 51 to line 56, column 54. The process is also described, for example, in U.S. Patent Nos. 7,608,668, 7,893,166, and 7,947,793.

[0043] The ethylene / α-olefin multiblock copolymer may contain more than one ethylene / α-olefin multiblock copolymer.

[0044] B. Free Radical Initiator The crosslinkable composition contains a free radical initiator. In one embodiment, the free radical initiator is an organic peroxide. Non-limiting examples of suitable organic peroxides include bis(1,1-dimethylethyl) peroxide, bis(1,1-dimethylpropyl) peroxide, 2,5-dimethyl-2,5-bis(1,1-dimethylethylperoxy)hexane, 2,5-dimethyl-2,5-bis(1,1-dimethylethylperoxy)hexyne, 4,4-bis(1,1-dimethylethylperoxy)valeric acid, butyl ester, 1,1-bis(1,1-dimethylethylperoxy)-3,3,5-trimethylcyclohexane, benzoyl peroxide, tert-butyl peroxybenzoate, di-tert-amyl peroxide (DTAP), bis(α-t-butyl-peroxyisopropyl) benzene (BIPB), isopropyl cumyl t-butyl peroxide, t-butyl cumyl peroxide, di-t-butyl peroxide, 2,5-bis(t-butylperoxy)-2,5-dimethylhexane, 2,5-bis(t-butylperoxy)-2,5-dimethylhex-3-yne, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, isopropyl cumyl cumyl peroxide, butyl 4,4-di(tert-butylperoxy)valerate, di(isopropyl cumyl) peroxide, dicumyl peroxide, and combinations thereof.

[0045] In one embodiment, the free radical initiator is dicumyl peroxide.

[0046] C.BiTEMPS methacrylate disulfide The crosslinkable polymer composition contains 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide, which is synonymously referred to as "BiTEMPS methacrylate" or "BiTEMPS" or "BiT". BiTEMPS methacrylate disulfide has the following Structure 1.

[0047] [Chemical]

[0048] In one embodiment, the crosslinkable composition comprises 70 wt% to 98.5 wt%, or 77 wt% to 98.5 wt% of an ethylene polymer, 0.5 wt% to 10 wt%, or 0.5 wt% to 5 wt%, 0.5 wt% to 3.0 wt%, or 0.5 wt% to 1.5 wt%, or 1.5 wt% to 3.0 wt% of a free radical initiator which is an organic peroxide (such as dicumyl peroxide, etc.), and 1 wt% to 20 wt%, or 1 wt% to 15 wt%, 3 wt% to 20 wt%, or 3 wt% to 10 wt% of BiTEMPS methacrylate disulfide. It is understood that the aggregate of the ethylene polymer, the free radical initiator, and BiTEMPS methacrylate disulfide (and optional additives) amounts to 100 wt% of the crosslinkable polymer composition.

[0049] The present disclosure provides a crosslinked composition. The crosslinkable polymer composition is melt blended at a temperature of 100°C to 250°C, or 120°C to 200°C, or 120°C to 180°C, or 120°C to 160°C to cause a crosslinking reaction to form a crosslinked composition. In one embodiment, the crosslinked composition comprises an ethylene polymer and 2,2,6,6 - tetramethyl - 4 - piperidyl methacrylate disulfide (BiTEMPS methacrylate). The crosslinked composition contains disulfide bonds formed from BiTEMPS methacrylate by the crosslinking reaction, and the disulfide bonds have the following Structure 2.

[0050] [Chemical]

[0051] The term "P" (and structure) in the above structure 2 refers to the chains of polymerized ethylene (and optional comonomers) of the ethylene-based polymer. The ethylene-based polymer of the crosslinked composition can be any ethylene-based polymer having an MI of 0.1 g / 10 min to 100 g / 10 min, as disclosed previously herein. Non-limiting examples of suitable ethylene-based polymers include ethylene plastomers / elastomers, high density polyethylene (HDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), ethylene / α-olefin multiblock copolymers, and combinations thereof.

[0052] In one embodiment, the ethylene-based polymer is an unused ethylene-based polymer. As used herein, an "unused ethylene-based polymer" is an ethylene-based polymer that has not been subjected to a crosslinking reaction. In other words, the term "unused ethylene-based polymer" refers to the ethylene-based polymer present in the crosslinked composition before the ethylene-based polymer is crosslinked with BiTEMPS methacrylate. The unused ethylene-based polymer is the ethylene-based polymer before crosslinking, and the crosslinked composition contains the same ethylene-based polymer that was unused but is now crosslinked with BiTEMPS methacrylate. In this way, the unused ethylene-based polymer serves as a baseline for evaluating the properties of the crosslinked composition. The crosslinked composition (i) has a storage modulus value E' at 140 °C that is greater than the storage modulus value E' of the unused ethylene-based polymer at 140 °C, (ii) has a tan delta value at 60 °C that is less than the tan delta value of the unused ethylene-based polymer at 60 °C, (iii) has a tan delta value at 140 °C that is less than the tan delta value of the unused ethylene-based polymer at 140 °C.

[0053] In one embodiment, the crosslinked composition comprises 80 wt% to 97 wt% of an ethylene-based polymer and 3 wt% to 20 wt% of BiTEMPS methacrylate, and the aggregate of the ethylene-based polymer and BiTEMPS methacrylate (and optional additives) amounts to 100 wt% of the crosslinked composition. The crosslinked composition (i) has a storage modulus value E' at 60°C greater than 1 MPa, and (ii) has a storage modulus value E' at 140°C greater than 0.1 MPa, and (iii) has a tan delta value at 60°C less than 0.17, and (iv) has a tan delta value at 140°C less than 0.62.

[0054] D. Blend Components In one embodiment, the crosslinkable composition and / or the crosslinked composition comprises blend components. Non-limiting examples of suitable blend components include ethylene vinyl acetate (EVA), polyolefins (e.g., polyethylene other than an ethylene-based polymer crosslinked with BiTEMPS methacrylate, and polypropylene), polymers (e.g., polystyrene, ABS, SBS, etc.), and combinations thereof. Non-limiting examples of suitable polyolefins include polyethylene, polypropylene, polybutylene (e.g., polybutene-1), poly(1-pentene), poly(1-hexene), poly(1-octene), poly(1-decene), poly(3-methyl-1-butene), poly(4-methyl-1-pentene), polyisoprene, polybutadiene, poly(1,5-hexadiene), interpolymers derived from olefins, interpolymers derived from olefins and other polymers, e.g., polyvinyl chloride, polystyrene, polyurethane, etc., and mixtures thereof.

[0055] In one embodiment, the polyolefin is a homopolymer such as polyethylene, polypropylene, polybutylene, poly(1-pentene), poly(3-methyl-1-butene), poly(4-methyl-1-pentene), polyisoprene, polybutadiene, poly(1,5-hexadiene), poly(1-hexene), poly(1-octene), and poly(1-decene).

[0056] Non-limiting examples of polyethylene (other than ethylene polymers crosslinked with BITEMPS methacrylate) suitable as blend components include ultra-low density polyethylene (ULDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), high molecular weight high density polyethylene (HMW-HDPE), ultra high molecular weight polyethylene (UHMW-PE), and combinations thereof. Non-limiting examples of polypropylene include low density polypropylene (LDPP), high density polypropylene (HDPP), high-melt strength polypropylene (HMS-PP), and combinations thereof. In one embodiment, the blend component is high-melt strength polypropylene (HMS-PP), low density polyethylene (LDPE), or a combination thereof.

[0057] E. Additives The crosslinkable composition and / or the crosslinked composition may contain one or more optional additives. Non-limiting examples of suitable additives include graft initiators, crosslinking catalysts, foaming agents, foaming agent activators (e.g., zinc oxide, zinc stearate, etc.), auxiliaries (e.g., triallyl cyanurate), plasticizers, processing oils, processing aids, carbon black, colorants or pigments, stability control agents, nucleating agents, fillers, antioxidants, acid scavengers, ultraviolet (UV) stabilizers, flame retardants, lubricants, processing aids, extrusion aids, and combinations thereof. When present, the total amount of the additives can be more than 0 to 80%, or 0.001% to 70%, or 0.01% to 60%, or 0.1% to 50%, or 0.1% to 40%, or 0.1% to 20%, or 0.1% to 10%, or 0.1% to 5% of the total weight of the composition.

[0058] In one embodiment, the crosslinkable composition and / or the crosslinked composition comprises an antioxidant. Non-limiting examples of suitable antioxidants include aromatic or hindered amines, such as alkyldiphenylamine, phenyl-α-naphthylamine, alkyl or aralkyl substituted phenyl-α-naphthylamine, alkylated p-phenylenediamine, tetramethyl-diaminodiphenylamine, etc., phenols, such as 2,6-di-t-butyl-4-methylphenol, 1,3,5-trimethyl-2,4,6-tris(3’,5-di-t-butyl-4,-hydroxybenzyl)benzene, tetrakis[(methylene(3,5-di-t-butyl-4-hydroxyhydrocinnamate)]methane (e.g., IRGANOX™ 1010 (Ciba Geigy, New York)), acryloyl modified phenol, octadecyl-3,5-di-t-butyl-4-hydroxycinnamate (e.g., IRGANOX™ 1076 commercially available from Ciba Geigy), phosphites and phosphonites, hydroxylamines, benzofuranone derivatives, and combinations thereof. When used, the amount of the antioxidant in the composition can be more than 0 to 5 wt%, 0.0001 to 2.5 wt%, or 0.001 to 1 wt%, or 0.001 to 0.5 wt% of the total weight of the composition.

[0059] In one embodiment, the crosslinkable composition and / or the crosslinked composition contains a UV stabilizer. Non-limiting examples of suitable UV stabilizers include benzophenone, benzotriazole, aryl ester, oxanilide, acrylic ester, formamidine, carbon black, hindered amine, nickel quencher, hindered amine, phenolic antioxidant, metal salt, zinc compound, and combinations thereof. When used, the amount of the UV stabilizer can be more than 0 to 5% by weight, or 0.01% to 3% by weight, or 0.1% to 2% by weight, or 0.1% to 1% by weight of the total weight of the composition.

[0060] In one embodiment, the crosslinkable composition and / or the crosslinked composition contains a colorant or pigment. Non-limiting examples of suitable colorants or pigments include inorganic pigments such as metal oxides such as iron oxide, zinc oxide, and titanium dioxide, mixed metal oxides, carbon black, organic pigments such as anthraquinone, ansanthrone, azo, and monoazo compounds, arylamide, benzimidazolone, BONA lake, diketopyrrolo-pyrrole, dioxazine, disazo compound, diarylide compound, flavanthrone, indanthrone, isoindolinone, isoindoline, metal complex, monoazo salt, naphthol, b-naphthol, naphthol AS, naphthol lake, perylene, perinone, phthalocyanine, pyranthrone, quinacridone, and quinophthalone, and combinations thereof. When used, the amount of the colorant or pigment in the composition can be more than 0 to 10% by weight, or 0.1% to 5% by weight, or 0.25% to 2% by weight of the total weight of the composition.

[0061] In one embodiment, the crosslinkable composition and / or the crosslinked composition includes a filler. Non-limiting examples of suitable fillers include talc, calcium, carbonate, chalk, calcium sulfate, clay, kaolin, silica, glass, fumed silica, mica, wollastonite, feldspar, aluminum silicate, calcium silicate, alumina, hydrated alumina such as alumina trihydrate, glass microspheres, barite, wood flour, glass fiber, carbon fiber, marble powder, cement powder, magnesium oxide, magnesium hydroxide, antimony oxide, zinc oxide, barium sulfate, titanium dioxide, titanates, and combinations thereof.

[0062] In one embodiment, the filler is barium sulfate, talc, calcium carbonate, silica, glass, glass fiber, alumina, titanium dioxide, or a mixture thereof. In a further embodiment, the filler is talc, calcium carbonate, barium sulfate, glass fiber, or a mixture thereof. When used, the amount of the filler in the composition can be more than 0% to 80% by weight, or 0.1% to 60% by weight, or 0.5% to 40% by weight, or 1% to 30% by weight, or 10% to 40% by weight of the total weight of the composition.

[0063] In one embodiment, the crosslinkable composition and / or the crosslinked composition includes a lubricant. Non-limiting examples of suitable lubricants include fatty alcohols and their dicarboxylic acid esters, fatty acid esters of short-chain alcohols, fatty acids, fatty acid amides, metal soaps, oligomeric fatty acid esters, fatty acid esters of long-chain alcohols, montan wax, polyethylene wax, polypropylene wax, natural and synthetic paraffin waxes, fluoropolymers, and combinations thereof. When used, the amount of the lubricant in the composition can be more than 0% to 5% by weight, or 0.1% to 4% by weight, or 0.1% to 3% by weight of the total weight of the composition.

[0064] In one embodiment, the crosslinkable composition and / or the crosslinked composition contains an antistatic agent. Non-limiting examples of suitable antistatic agents include conductive fillers (e.g., carbon black, metal particles, and other conductive particles), fatty acid esters (e.g., glycerol monostearate), ethoxylated alkylamines, diethanolamide, ethoxylated alcohols, alkyl sulfonates, alkyl phosphates, quaternary ammonium salts, alkyl betaines, and combinations thereof. When used, the amount of the antistatic agent in the composition can be more than 0 wt% to 5 wt%, or 0.01 to 3 wt%, or 0.1 to 2 wt% of the total weight of the composition.

[0065] In one embodiment, the crosslinkable composition and / or the crosslinked composition contains a foaming agent. A "foaming agent" is a substance that can generate a bubble structure in the composition through a foaming process. The foaming agent is used to foam the crosslinked composition. Non-limiting examples of suitable foaming agents include inorganic physical foaming agents such as air, argon, nitrogen, carbon dioxide, argon, helium, oxygen, and neon, and aliphatic hydrocarbons such as propane, n-butane, isobutane, n-pentane, isopentane, and n-hexane, alicyclic hydrocarbons such as cyclohexane and cyclopentane, halogenated hydrocarbons such as chlorofluoromethane, trifluoromethane, 1,1-difluoroethane, 1,1,1,2-tetrafluoroethane, methyl chloride, ethyl chloride, and methylene chloride, and organic physical foaming agents such as dialkyl ethers such as dimethyl ether, diethyl ether, and methyl ethyl ether.

[0066] Non-limiting examples of suitable organic blowing agents include aliphatic hydrocarbons having 1 to 6 carbon atoms, aliphatic alcohols having 1 to 3 carbon atoms, and fully and partially halogenated aliphatic hydrocarbons having 1 to 4 carbon atoms. Non-limiting examples of suitable aliphatic hydrocarbons include methane, ethane, propane, n-butane, isobutane, n-pentane, isopentane, neopentane, and the like. Non-limiting examples of suitable aliphatic alcohols include methanol, ethanol, n-propanol, and isopropanol. Non-limiting examples of suitable fully and partially halogenated aliphatic hydrocarbons include fluorocarbons, chlorocarbons, and chlorofluorocarbons. Non-limiting examples of suitable fluorocarbons include fluorinated methyl, perfluoromethane, fluorinated ethyl, 1,1-difluoroethane (HFC152a), 1,1,1-trifluoroethane (HFC-143a), 1,1,1,2-tetrafluoroethane (HFC-134a), pentafluoroethane, difluoromethane, perfluoroethane, 2,2-difluoropropane, 1,1,1-trifluoropropane, perfluoropropane, dichloropropane, difluoropropane, perfluorobutane, perfluorocyclobutane. Non-limiting examples of suitable partially halogenated chlorocarbons and chlorofluorocarbons include methyl chloride, methylene chloride, ethyl chloride, 1,1,1-trichloroethane, 1,1-dichloro-1-fluoroethane (HCFC-141b), 1-chloro-1,1-difluoroethane (HCFC-142b), 1,1-dichloro-2,2,2-trifluoroethane (HCFC-123), and 1-chloro-1,2,2,2-tetrafluoroethane (HCFC-124). Non-limiting examples of suitable fully halogenated chlorofluorocarbons include trichloromonofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), trichlorotrifluoroethane (CFC-113), 1,1,1-trifluoroethane, pentafluoroethane, dichlorotetrafluoroethane (CFC-114), chloroheptafluoropropane, and dichlorohexafluoropropane.Non-limiting examples of suitable chemical blowing agents include azodicarbonamide, azodiisobutyronitrile, benzenesulfohydrazide, 4,4-oxybeneznesulfonyl-semicarbazide, p-toluenesulfonyl semicarbazide, barium azodicarboxylate, N,N'-dimethyl-N,N'-dinitrosoterephthalamide, and trihydrazinotriazine.

[0067] BiTEMPS methacrylate is a "dynamic crosslinking agent". The dynamic crosslinking agent BiTEMPS methacrylate enables the formation of a crosslinked network with an ethylene-based polymer by disulfide bonds between the chains of the ethylene-based polymer (in the presence of a free radical initiator) to form a crosslinked ethylene-based polymer composition. When the crosslinked ethylene-based polymer composition is subjected to a "reprocessing temperature" that is a temperature of 120°C to 160°C, or 130°C to 160°C, the disulfide bonds can be broken, allowing chain mobility and exchange, so the crosslinking is dynamic. At the reprocessing temperature, the disulfide bonds in the crosslinked ethylene-based polymer composition are broken, forming a reprocessable ethylene-based polymer composition. When the reprocessable ethylene-based composition is cooled below the reprocessing temperature, a re-crosslinked ethylene-based polymer composition is formed.

[0068] The dynamic crosslinking agent BiTEMPS methacrylate enables periodic “reprocessing” for the secondary fabrication of new polymer articles. When a crosslinked ethylene-based polymer composition is heated to the reprocessing temperature, the disulfide bonds are broken or otherwise cleaved, enabling the previously crosslinked ethylene-based polymer composition to flow at the reprocessing temperature and form a “reprocessable ethylene-based polymer composition”. Heating to the reprocessing temperature enables bond breakage and polymer chain flow, allowing the ethylene-based composition to be readily reshaped. At the reprocessing temperature, the reprocessable ethylene-based polymer composition is no longer crosslinked, but rather is fluid, now enabling the formation and / or secondary processing of the fluid reprocessable ethylene-based composition (including BiTEMPS methacrylate) into a new preform or article. Cooling below the “reprocessing temperature” reforms the disulfide bonds, reconstructs the network, and forms a re-crosslinked ethylene-based composition with the new article configuration, returning to the high viscosity (non-flowing at room temperature) and resistance to mechanical deformation characteristic of the crosslinked network. When the newly formed article of the reprocessable ethylene-based polymer composition is cooled below the reprocessing temperature, the disulfide bonds in the reprocessable ethylene-based polymer composition are reconstructed, and the ethylene-based polymer (including BiTEMPS methacrylate) becomes a re-crosslinked ethylene-based polymer composition assuming the shape of the newly secondary processed article. Below the reprocessing temperature, the network disulfide bonds are stable, and the re-crosslinked ethylene-based polymer composition exhibits the high viscosity characteristic of the crosslinked network and resistance to mechanical deformation. This cycle of crosslinking / reprocessing / re-crosslinking and secondary processing into new articles can be repeated.

[0069] Although not bound by a particular theory, the number of "reprocessing" cycles that are possible using the present crosslinked ethylene-based composition (before competing heat and oxidative permanent crosslinking occur and prevent further reprocessing) can be determined by calculating the ratio of the melt viscosities of the crosslinked ethylene-based polymer composition before and after the reprocessing cycle. For a crosslinked ethylene-based polymer composition that is reprocessable, the ratio of the Mooney viscosity after reprocessing to the Mooney viscosity before reprocessing is from 0.5 to 5, or from 0.7 to 3, or from 0.9 to 2, or from 0.95 to 1.2.

[0070] As another measurement criterion for monitoring the number of "reprocessing" cycles that are possible using the BiTEMPS methacrylate dynamic crosslinking agent before competing oxidative permanent crosslinking occurs, visual observation can be mentioned. A formed film that has been mechanically deformed is heated to the reprocessing temperature and visually inspected to determine whether the mechanically deformed film recovers to form a stable film. This measurement criterion for reprocessability is shown in Table 2 below.

[0071] The present disclosure provides a process. In one embodiment, the process comprises heating a first article to a reprocessing temperature. The first article is composed of a crosslinked ethylene-based polymer composition comprising (i) an ethylene-based polymer and (ii) 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate). The process comprises forming, at the reprocessing temperature, the first article into a reprocessable ethylene-based polymer composition. The process comprises shaping, at the reprocessing temperature, the reprocessable ethylene-based composition into a reprocessed preform. The process comprises cooling the reprocessed preform to below the reprocessing temperature and forming a second article composed of a re-crosslinked ethylene-based polymer composition composed of (i) an ethylene-based polymer and (ii) BiTEMPS methacrylate, the second article being different from the first article.

[0072] In one embodiment, the forming step is a procedure selected from the group consisting of injection molding, extrusion molding, thermoforming, slush molding, overmolding, insert molding, blow molding, cast molding, tentering, compression molding, and combinations thereof.

[0073] Non-limiting examples of articles (first article and second article) suitable for the present crosslinked / re-crosslinked ethylene-based polymer (including BiTEMPS methacrylate) compositions include elastic films, elastic fibers, soft-touch items such as toothbrush handles and instrument handles, gaskets and profiles, adhesives (including hot melt adhesives and pressure-sensitive adhesives), footwear (including shoe soles and shoe liners), automotive interior parts and profiles, foam articles (both open-cell foams and closed-cell foams), impact modifiers for other thermoplastic polymers, such as high-density polyethylene, isotactic polypropylene, or other olefin polymers, coated fabrics, hoses, tubes, overlays, cap liners, flooring materials, and combinations thereof.

[0074] By way of example and not limitation, some embodiments of the present disclosure will now be described in detail in the following examples.

[0075] 1. Materials The materials used in the comparative sample (CS) and the inventive examples (IE) of the present invention are provided in Table 1 below.

[0076]

Table 1

[0077] 1. Synthesis of BiTEMPS Methacrylate To synthesize BiTEMPS methacrylate, 2,2,6,6 - tetramethyl - 4 - piperidyl methacrylate (8.78 g, 39.0 mmol, supplied by TCI America) is first dissolved in anhydrous petroleum ether (about 90 mL, supplied by Sigma - Aldrich and dried with molecular sieves for 48 hours before use), and cooled to - 70 °C in a dry ice / acetone bath. Then, sulfur monochloride (1.30 g, 9.7 mmol, supplied by Sigma - Aldrich) is dissolved in anhydrous petroleum ether (about 1.25 mL) and added dropwise to the reaction vessel over 30 minutes. The solution is stirred at - 70 °C for an additional 30 minutes and at room temperature for 15 minutes. Next, the reaction solution is poured into a large amount of distilled water and stirred overnight at room temperature to precipitate BiTEMPS methacrylate. The precipitate is collected, vacuum filtered, and dried under vacuum at 60 °C for 48 hours to obtain BiTEMPS methacrylate shown as Structure 1 below.

[0078]

Chemical formula

[0079] 2. Preparation of the cross - linked composition Weigh out appropriate masses of starting materials, including polymer pellets (ethylene-based polymers), a crosslinking agent (BiTEMPS methacrylate), and a radical initiator (DCP) separately using a chemical balance (typically, 2 g of polymer, 0.1 g of crosslinking agent, and 0.02 g of radical initiator). Before synthesis, load the polymer of interest, heat it above its melt transition point, and mix for 3 - 5 minutes to wash out impurities from the cup of a Dynisco (formerly Atlas) Laboratory Mixing Molder (LMM). After washing out the polymer fragments, add the bulk polymer pellets and the powder mixture of the crosslinking agent and the radical initiator to the cup using a spatula. Add the starting materials in doses such that they are uniformly distributed throughout the cup before mixing. In addition, add three steel balls (about 5 mm in diameter) uniformly to the cup to mimic the extrusion process during melt-state mixing. Next, raise the temperature of the LMM above the melt transition point of the polymer and mix the starting materials at this temperature at 120 rpm (maximum rotational speed) for 3 - 5 minutes to ensure homogenization of the components in the melt state while minimizing radical initiation. For polymers 4 - 6, this mixing temperature is 100 °C. For polymers 2 and 7 - 10, this mixing temperature is 130 °C. For polymer 1, this mixing temperature is 140 °C. After this homogenization, raise the temperature of the LMM to 160 °C to initiate the radical initiation and crosslinking agent grafting process. Mix at this temperature for about 20 minutes. During mixing, manually cycle the rotor of the LMM up and down periodically to promote homogenization of the blend. After mixing for 20 minutes, stop the mixing and remove the crosslinked polymer blend from the cup using a spatula.

[0080] The crosslinked composition (network blend) is cut into small pieces and compression molded into a film having dimensions of 50 mm in length, 25 mm in width, and 0.65 mm in thickness at 160 °C and 8 MPa for 30 minutes in a PHI press (Model 0230C-X1) to obtain a first molded sample. The film is cut into millimeter-sized small pieces and compression molded under the same conditions to obtain a second molded sample, and this procedure is repeated again to obtain a third molded sample. Strips are cut from each sample film for dynamic mechanical analysis (DMA).

[0081] 3. Polymer 7 (INFUSE™ 9100) IE1 of Polymer 7 (INFUSE™ 9100) was selected and thermal property recovery was demonstrated by collecting DSC data after each successive compression molding reuse (up to 3 times) (Table 4). A heating rate of 10 °C / min and a cooling rate of -40 °C / min were adapted for all measurements in the temperature range of -60 °C to 160 °C.

[0082] The processability of the Polymer 7 (INFUSE™ 9100) crosslinked composition (network blend) was evaluated by film quality after completing the aforementioned standard compression molding procedure and conditions in Table 2 (below). The thermomechanical properties of the Polymer 7 (INFUSE™ 9100) crosslinked composition (network blend) were also tested by DMA to evaluate the network response for the first molded sample compared to the unused Polymer 7 (INFUSE™ 9100) material. Therefore, the performance criteria are based on the properties of the unused Polymer 7.

[0083]

Table 2

[0084] Table 2 (above) shows Examples (IE) and comparative samples of the inventive cross - linkable compositions containing Polymer 7 (INFUSE™ 9100) with various amounts of BiTEMPS methacrylate (“BiT” cross - linker) and various amounts of dicumyl peroxide (“DCP” radical initiator). The cross - linkable compositions of Table 2 were mixed in a Laboratory Mixing Molder (LMM) as described above to form cross - linked compositions. Subsequently, each cross - linked composition sample was cut into small pieces (each piece being 50 mm in length, 25 mm in width, and 0.65 mm in thickness) and compression - molded into a film of 1 mm thickness at 160 °C and 8 MPa for 30 minutes in a PHI press (Model 0230C - X1) to obtain a first molded sample.

[0085] The properties of each cross - linked film sample are shown in Table 2 as “Properties Tested”. In Table 2, the fact that the minimum E’ at 140 °C is 0.1 MPa demonstrates that the network response (cross - linking) exceeds the thermoplastic response of the unused Polymer 7 (formulation CS1) having a cross - linker and a radical initiator. Typically, the synthesis of a dynamic network by the described procedure has been successful for most polymers using 5 wt% cross - linker and 1 wt% radical initiator. Table 2 shows (i) varying the amount of radical initiator while keeping the amount of BiT cross - linker constant at 5 wt% of the cross - linker amount. Table 2 also shows (ii) varying the amount of BiT cross - linker while keeping the amount of radical initiator constant at 1 wt%. This two - pronged approach enabled the evaluation of the limits for achieving the network response (cross - linking) for the model polymer (in this case, Polymer 7) while maintaining processability in a compression - molding machine.

[0086] From Table 2, the viable ranges of the crosslinking agent (BiT) and the radical initiator (DCP) for Polymer 7 with respect to the loading mass of Polymer 7 are 3 wt% to 20 wt% and 0.5 to 1.25 wt%, respectively. In these ranges, a network response (crosslinking) exceeding 0.1 MPa at 140 °C can be obtained, and the partial or complete processability can be evaluated based on the film quality after compression molding. In Table 2, the crosslinked compositions IE1, IE3, IE4, IE5, and IE6 are completely processable (score 3 for processability / film quality). The E’ value of IE1 (5 wt% crosslinking agent and 1 wt% radical initiator with respect to a 2 g Polymer 7 loading mass) at 140 °C is 0.992, which correlates with a strong dynamic network response. The comparative samples CS1 - CS9 in Table 2 either did not produce a network material due to insufficient crosslinking agent or radical initiator (CS1 - 2, 5), or could not be processed after compression molding due to overloading of the radical initiator, forming a permanent crosslink where dynamic chemistry was not possible (CS3 - 4, 6 - 9). Therefore, the Polymer 7 (INFUSE™ 9100) materials synthesized from CS1 - CS9 either flow above the melt transition temperature or cannot produce a recovered film, so neither of them can be characterized by DMA.

[0087] In addition, using the Polymer 7 (INFUSE™ 9100) IE1 formulation, the minimum compression molding time required for processing at 160 °C and 8 MPa in Table 3 below was evaluated.

[0088]

Table 3

[0089] Table 3 (above) shows that 25 minutes is the minimum amount of time required to partially process the Polymer 7 (INFUSE™ 9100) IE1 formulation in a compression molding machine at 160 °C and 8 MPa, and 30 minutes is the minimum amount of time required to completely process this formulation under the same conditions. This supports the standard processing procedure for other polymers including a 30 - minute press time.

[0090] Table 4 (below) shows three consecutive molding cycles tested by DSC to demonstrate the thermal properties of Polymer 7 (INFUSE™ 9100) containing the as-synthesized material and the recovery of those thermal properties. The IE1 of Polymer 7 recovers in terms of the values of crystallinity and melting temperature range upon reuse as compared to the as-synthesized network.

[0091]

Table 4

[0092] As shown in Table 4 above, the IE1 of Polymer 7 recovers in terms of the values of crystallinity and melting temperature range upon reuse as compared to the as-synthesized network.

[0093] 4. Polymers 1 - 10 Based on the findings for Polymer 7 (INFUSE™ 9100), the IE1 formulation of Polymer 7 (2 g polymer base, 5 wt% crosslinker, 1 wt% radical initiator) was converted for Polymers 1 - 6 and 8 - 10. With this formulation, for Polymers 1 - 6 and 8 - 10, sufficient network response and complete recovery of thermomechanical properties were obtained after three consecutive compression molding cycles as evaluated using DMA.

[0094] Table 5 is provided below.

[0095]

Table 5

[0096] Table 5 shows E’ and tanδ at both 60 °C and 140 °C for the IE1 formulations of Polymers 1 - 10. The E’ values of the network polymers at 60 °C are equal (same order of magnitude) to the E’ values of the respective virgin polymers, within the range of experimental uncertainty. Depending on the changes in dynamic crosslinking and crystallinity after processing compared to the virgin polymers, the E’ values at this temperature may be slightly lower (due to a decrease in crystallinity, the E’ decreases below the melting transition point despite an improvement due to crosslinking) or slightly higher (the crystallinity is slightly affected and the E’ is improved due to crosslinking). The continuous moldings at this temperature for each of the IE1 polymer formulations show E’ values that are approximately equal (same order of magnitude) to the E’ values of the respective virgin polymers and the first molding samples, within the range of experimental uncertainty.

[0097] At 140 °C, the E’ values of the network polymer IE1 - IE10 crosslinked compositions are greater than the E’ values of the respective virgin Polymers 1 - 10. This is because the virgin Polymers 1 - 10 do not have network characteristics that would give large E’ values (> 0.1 MPa) above the melting transition point. The continuous moldings at 140 °C for each of the IE1 - 10 polymer crosslinked compositions show E’ values that are approximately equal (same order of magnitude) to the E’ values of the first molding samples, within the range of experimental uncertainty, or slightly higher (due to additional crosslink formation during processing).

[0098] Consistent with a greater presence of crosslinking in the network materials, the tanδ values at both 60 °C and 140 °C are smaller for the IE1-10 crosslinked compositions (network formulations) compared to their respective un-used corresponding polymers 1-10. Additionally, these values are maintained for samples continuously molded at both 60 °C and 140 °C. The IE1-10 crosslinked compositions presented in Table 5 demonstrate that not only do polymers 1-10 give a substantial dynamic network response (above 1 MPa at 60 °C and above 0.1 MPa at 140 °C) upon crosslinking, but they are reprocessable and recover their E’ and tanδ values after continuous compression molding cycles. Comparable samples that are processable do not achieve a substantial network response, and comparable samples that give a substantial network response cannot be reprocessed and do not recover their thermo-mechanical properties after processing because there is permanent crosslinking rather than sufficient dynamic crosslinking.

[0099] Table 5 provides the thermal properties (melting range and crystallinity) of the un-used polymers 1-10 (comparative samples) and the IE1-10 crosslinked compositions (network formulations) of the examples of the present invention as determined by DSC. The reactive crosslinking reduces the order of the crystal structures formed during processing after cooling, slightly reduces the crystallinity of the network polymers compared to their un-used corresponding polymers 1-10 (comparative samples), and also reduces their melting peaks and endpoints.

[0100] Table 6 below shows high temperature creep data for (i) un-used INFUSE™ 9100 ethylene / octene multiblock copolymer (comparative sample), (ii) a crosslinked ethylene-based polymer composition composed of 5 wt% BiTEMPS methacrylate, (IE7-1), (iii) ENGAGE™ 8003 ethylene / octene random copolymer (comparative sample), and (iv) a crosslinked ethylene-based composition composed of ENGAGE™ 8003, an ethylene / octene random copolymer, and 5 wt% BiTEMPS methacrylate (IE4-1).

[0101]

Table 6

[0102] The present disclosure is not limited to the embodiments and examples contained herein, and it is particularly intended to include, to the extent applicable to the following claims, modified forms of those embodiments that include portions of the embodiments and combinations of elements of different embodiments.

Claims

**Claim 1** A crosslinkable polymer composition comprising: an ethylene-based polymer; a free radical initiator; 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate). **Claim 2** The crosslinkable polymer composition according to claim 1, wherein the ethylene-based polymer has a melt index of 0.1 g / 10 min to 100 g / 10 min. **Claim 3** The crosslinkable polymer composition according to claim 1 or 2, wherein the ethylene-based polymer is selected from the group consisting of ethylene plastomer / elastomer, high density polyethylene (HDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), ethylene / α-olefin multiblock copolymer, and combinations thereof. **Claim 4** The crosslinkable polymer composition according to any one of claims 1 to 3, wherein the free radical initiator is an organic peroxide. **Claim 5** 70% to 98.5% by weight of the ethylene-based polymer; 0.5% to 10.0% by weight of the free radical initiator; 1% to 20% by weight of BiTEMPS methacrylate. **Claim 6** The crosslinkable polymer according to any one of claims 1 to 5, wherein the free radical initiator is dicumyl peroxide. **Claim 7** A crosslinked composition comprising: an ethylene-based polymer; 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate). **Claim 8** The crosslinked composition according to claim 7, wherein the crosslinked composition contains the bond of Structure 2. 【Chemical Formula 1】 **Claim 9** 80% to 99% by weight of an ethylene-based polymer having a melt index of 0.1 g / 10 min to 100 g / 10 min; 20% to 1% by weight of the BiTEMPS methacrylate. **Claim 10** The crosslinked composition according to any one of claims 7 to 9, wherein the ethylene-based polymer is selected from the group consisting of ethylene plastomer / elastomer, high density polyethylene (HDPE), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), ethylene / α-olefin multiblock copolymer, and combinations thereof. **Claim 11** The ethylene-based polymer is an unused ethylene-based polymer before the crosslinked composition is crosslinked, The crosslinked composition, (i) a storage elastic modulus value E' at 140°C that is greater than the storage elastic modulus value E' of the unused ethylene-based polymer at 140°C, and (ii) a tan delta value at 60°C that is less than the tan delta value of the unused ethylene-based polymer at 60°C, and (iii) a tan delta value at 140°C that is less than the tan delta value of the unused ethylene-based polymer at 140°C. The crosslinked composition according to any one of claims 7 to 10.

12. containing 3% to 20% by weight of BiTEMPS methacrylate, The crosslinked composition, and (i) a storage elastic modulus value E' at 60°C that is greater than 1 MPa, and (ii) a storage elastic modulus value E' at 140°C that is greater than 0.1 MPa, and (iii) a tan delta value at 60°C that is less than 0.17, and (iv) a tan delta value at 140°C that is less than 0.

62. The crosslinked composition according to any one of claims 7 to 11.

13. A process, heating a first article, the first article being composed of a crosslinked ethylene-based polymer composition containing (i) an ethylene-based polymer and (ii) 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate) to a reprocessing temperature; forming the first article into a reprocessable ethylene-based polymer composition at the reprocessing temperature; forming the reprocessable ethylene-based composition into a reprocessed preform at the reprocessing temperature; cooling the reprocessed preform to a temperature below the reprocessing temperature to form a second article composed of a re-crosslinked ethylene-based polymer composition composed of (i) the ethylene-based polymer and (ii) the BiTEMPS methacrylate, the second article being different from the first article. A process comprising.

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