Reversible cross-linked extruded profiles and processes

Abstract

The present disclosure provides an article. In one embodiment, the article is an extruded profile composed of a crosslinked composition formed from starting materials including an ethylene polymer and 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate). Thereby, an extruded profile composed of a crosslinked composition including (i) an ethylene polymer and (ii) a bond having Structure 2 is obtained. 【Chemical 1】 JPEG2025524617000014.jpg26170

Description

Technical Field

[0001] Thermally cured crosslinked polyolefin elastomers are widely used in automotive weather seals and in transportation and infrastructure applications such as under hoods, hoses, and belts. One conventional procedure for producing thermally cured crosslinked polyolefin elastomers is profile extrusion. In profile extrusion, peroxide crosslinking of polyolefin elastomers can produce network polymers with improved thermomechanical properties (such as compression set and creep resistance at elevated temperatures). Peroxide crosslinking creates C-C chemical bonds that are very stable and cannot be readily dissociated further by heating or mechanical shear, thus limiting the reuse or recycling of post-industrial scrap.

[0002] Given the worldwide attention to the carbon neutrality and recyclability of plastic materials, the art recognizes the need for thermally cured crosslinked extrusions that can be reprocessed and / or recycled.

Summary of the Invention

[0003] The present disclosure provides an article. In one embodiment, the article is an extrusion formed from a crosslinked composition formed from starting materials including an ethylene-based polymer and 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate). Thereby, an extrusion formed from a crosslinked composition including (i) an ethylene-based polymer and (ii) a bond having Structure 2 is obtained.

[0004]

Chemical Formula

[0005] The present disclosure provides a process. In one embodiment, the process includes heating a first article to a reprocessing temperature, the first article being composed of an extruded shape formed from a crosslinked composition comprising (i) an ethylene-based polymer and (ii) a bond having structure (2).

[0006]

Chemical formula

[0007] The coating is formed from starting materials of an ethylene-based polymer and 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS) methacrylate. The process includes heating the coating to the reprocessing temperature and forming the coating into a reprocessable ethylene-based polymer composition at the reprocessing temperature. The process includes shaping the reprocessable ethylene-based polymer composition into a reprocessed preform at the reprocessing temperature. The process includes cooling the reprocessed preform to below the reprocessing temperature to form a second article composed of a re-crosslinked ethylene-based polymer composition comprising (i) an ethylene-based polymer and (ii) a bond having structure (2).

[0008] Definitions All references to the Periodic Table of the Elements herein shall refer to the Periodic Table of the Elements published and copyrighted in 2003 by CRC Press, Inc. Also, any reference to a group shall be to the group reflected in the Periodic Table of the Elements for that element using the IUPAC system for numbering groups. Unless otherwise indicated, unless implicit from the context, or unless customary in the art, all parts and percentages are by weight. For the 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. versions are so incorporated by reference).

[0009] The numerical ranges disclosed in this specification include all values from the lower limit to the upper limit (including the boundary values). In the case of a range that includes explicit values (for example, a range of 1 or 2 or 3 to 5 or 6 or 7), any partial range between the two explicit values is included (for example, the above range of 1 to 7 includes partial ranges such as 1 to 2, 2 to 6, 5 to 7, 3 to 7, 5 to 6, etc.).

[0010] 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.

[0011] 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.

[0012] 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 they are specifically disclosed. To avoid any doubt, all compositions claimed through the use of the term "comprising" may include any additional additives, adjuvants, or compounds, whether polymeric or otherwise, unless there is a conflicting description. 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 for operation. The term "consisting of" excludes any constituent, step, or procedure that is not specifically depicted or listed.

[0013] "Ethylene polymer" is a polymer that contains more than 50 mol% of polymerized ethylene monomer (based on the total amount of polymerizable monomers) and optionally may contain at least one comonomer. Ethylene polymers include ethylene homopolymers and ethylene copolymers (meaning units derived from ethylene and one or more comonomers). The terms "ethylene polymer" and "polyethylene" may be used synonymously. Non-limiting examples of ethylene 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), ethylene / α-olefin multiblock 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, homogeneous catalyst systems containing ligand structures such as non-metallocene metal centers, 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 a single reactor or a multi-reactor configuration.

[0014] "Ethylene plastomer / elastomer" is a unit derived from ethylene and at least one C3 - C 10It is a substantially linear or linear ethylene / α-olefin interpolymer containing a uniform short-chain branching distribution comprising units derived from an α-olefin comonomer. Ethylene plastomers / elastomers have a density of 0.8540 g / cc to 0.917 g / cc. Non-limiting examples of ethylene plastomers / elastomers include AFFINITY™ polyolefin plastomers and ENGAGE™ polyolefin elastomers (available from The Dow Chemical Company), EXACT™ plastomers (available from ExxonMobil Chemical), Tafmer™ alpha-olefin copolymers (available from Mitsui), Solumer™ polyolefin elastomers and Supreme™ polyolefin elastomers (available from SK Chemicals Co.), and Lucene™ polyolefin elastomers (available from LG Chem Ltd.).

[0015] "High density polyethylene" (or "HDPE") is an ethylene homopolymer, or an ethylene / α-olefin copolymer containing at least one C4 - C 10 α-olefin comonomer or C4 - C8 α-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 the 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 (bimodal) and copolymers having three or more peaks. Non-limiting examples of HDPE include DOW (trademark) high density polyethylene (HDPE) resin (available from The Dow Chemical Company), ELITE (trademark) enhanced polyethylene resin (available from The Dow Chemical Company), CONTINUUM (trademark) bimodal polyethylene resin (available from The Dow Chemical Company), LUPOLEN (trademark) (available from LyondellBasell), and HDPE products from Borealis, Ineos, and ExxonMobil.

[0016] “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 uniform or 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 ELITE (trademark) enhanced polyethylene resin, 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).

[0017] “Low density polyethylene” (or “LDPE”) is an ethylene homopolymer or has a density of 0.915 g / cc to 0.940 g / cc and contains at least one C3-C having a broad MWD and long chain branching. 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 AGILITY (trademark) Performance LDPE and DOW (trademark) LDPE (available from The Dow Chemical Company), MarFlex (trademark) (Chevron Phillips), LUPOLEN (trademark) (LyondellBasell), and LDPE products from Borealis, Ineos, ExxonMobil, and others.

[0018] As used herein, "olefinic polymer" or "polyolefin" is a polymer that contains a polymerized olefin monomer greater than 50 mole percent (based on the total amount of polymerizable monomers) and optionally may contain at least one comonomer. Non-limiting examples of olefinic polymers include ethylene-based polymers and propylene-based polymers.

[0019] A "polymer" is a compound prepared by polymerizing monomers, whether of the same or different types, that provides in polymerized form a plurality of and / or repeating "units" or "structural units" that make up the polymer. 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 encompasses 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-described copolymers prepared by polymerizing ethylene or propylene, respectively, and one or more additional polymerizable α-olefin monomers. Polymers are often referred to as being "made from" one or more specified monomers, such as being "based on" a specified monomer or type of monomer and "containing" a specified monomer content. In this context, it should be noted that the term "monomer" is understood to refer to the polymerized residue of the specified monomer and not to non-polymerized species. Generally, polymers herein are referred to as being based on "units" that are the polymerized form of the corresponding monomers.

[0020] Test Methods Compression set. Compression set (or "Cset") was measured on one specimen per sample using one test piece per specimen according to ASTM D395 Method B and Type 1 specimen dimensions at 25% strain for 22 hours (hr) at 70 °C and at 25% strain for 22 hours at 100 °C.

[0021] Density was measured in accordance with ASTM D792 and the results were reported in g / cc at 25 °C.

[0022] Rheological analysis using a Rubber Process Analyzer (RPA). The rheology of the composition was measured using an Alpha Technologies RPA 2000 instrument, a rotorless oscillatory shear rheometer, in accordance with ASTM D6204, based on the following test conditions and exceptions. The sample was placed between two Mylar films for analysis. Rheology was monitored during an initial timed test at 160 °C, 1.0 rad / s, and 7% strain for 60 minutes. The elastic torque S’ at the end of the 60-minute crosslinking process was recorded. Immediately after 60 minutes at 160 °C, a frequency sweep from 0.1 to 300 rad / s was performed on the same sample at 160 °C and 7% strain, then a frequency sweep from 0.1 to 300 rad / s was performed at 190 °C and 7% strain, and then a frequency sweep from 0.1 to 300 rad / s was performed at 230 °C and 7% strain. The dynamic complex viscosity η * , and tan delta were recorded for each frequency sweep. In ASTM D6204, the frequency sweep for unvulcanized rubber is performed before the curing process. In this case, the frequency sweep was performed after the first crosslinking step at 160 °C to evaluate the reversibility of crosslinking.

[0023] Dynamic mechanical analysis (DMA). DMA experiments were performed using a TA Instruments RSA-G2 Solid Analyzer to measure the storage modulus (G’), loss modulus (G’’), and damping ratio (tan δ) of the network as a function of temperature and reuse under a nitrogen atmosphere. DMA was operated in tension mode at a frequency of 1 Hz with a vibration strain of 0.03%. Data were collected from room temperature to 160 °C at a heating rate of 3 °C / min.

[0024] The melt index (MI or I2) of (ethylene-based polymers) was measured in accordance with 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).

[0025] Tensile measurement at 80 °C. The tensile measurement was performed on an INSTRON device at an elongation rate of 1 inch / min in accordance with ASTM D1708 standard. The tensile bars were prepared by die-cutting from a compression-molded sheet with a thickness of 1.5 mm. The test was carried out in an environmental chamber whose temperature was equilibrated at 80 °C for 30 minutes before the test. Here, the tensile strength was recorded to reflect whether the material has cross-linking characteristics, which is the maximum stress applied before the sample breaks. These parameters were averaged by repeating the tensile measurement three times. The cross-linked part typically has a significantly higher breaking-point tensile strength compared to the non-cross-linked part.

Mode for Carrying Out the Invention

[0026] The present disclosure is directed to an article. The article includes an extruded profile. The extruded profile is composed of a cross-linked polymer composition formed from starting materials including (i) an ethylene-based polymer and (ii) 2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate).

[0027] A. Extruded Profile The present disclosure is directed to an article that includes, or alternatively is, an extruded profile. As used herein, an "extruded profile" (or "profile") is a three-dimensional shaped object composed of a polymeric composition, having length, width, and height, and the shaped object has a constant cross-sectional shape along its length. The cross-sectional shape is constant (or otherwise uniform) along, or substantially along, the entire length of the shaped object. The extruded profile is formed by forcing a molten polymeric composition through a die outlet and cooling the molten polymer as it exits the die outlet. Non-limiting examples of the (constant) cross-sectional shape of the extruded profile include circular, elliptical, polygonal, ring-shaped, triangular, square, and rectangular. Non-limiting examples of the extruded profile include film, fiber, rod, tube, pipe, sheet, rubber tube, extruded automotive rubber profile, and weatherstrip.

[0028] B. Ethylene-Based Polymer An article comprising (or being) an extruded profile is formed from a crosslinkable polymer composition (synonymously referred to as "starting material") comprising 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 multiblock copolymers, and combinations thereof.

[0029] In one embodiment, the ethylene-based polymer is an ethylene plastomer / elastomer.

[0030] In one embodiment, the ethylene-based polymer is HDPE.

[0031] In one embodiment, the ethylene-based polymer is LLDPE.

[0032] In one embodiment, the ethylene-based elastomer is an ethylene / α-olefin multi-block copolymer. The term "ethylene / α-olefin multi-block copolymer" refers to an ethylene / C4-C8α-olefin multi-block copolymer composed of polymerized 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 polymerized monomer units with different chemical or physical properties, and the blocks are joined (or covalently bonded) linearly. That is to say, the polymer contains chemically distinct units with ends joined to the polymerized ethylenic functional groups. Ethylene / α-olefin multi-block copolymers include block copolymers having two blocks (diblocks) and more than two blocks (multi-blocks). The C3-C8α-olefin is selected from propylene, butene, hexene, and octene. The ethylene / α-olefin multi-block copolymer does not contain, or alternatively excludes, styrene (i.e., styrene-free), and / or vinyl aromatic monomers, and / or conjugated dienes. When referring to the amount of "ethylene" or "comonomer" in the copolymer, this is understood to refer to its polymerized unit. In some embodiments, the ethylene / α-olefin multi-block copolymer has the following formula: (AB) nIt can 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 usually 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 substantially randomly distributed within the block. In other words, neither block A nor block B contains two or more subsegments (or subblocks) of distinct composition, such as a tip segment having a composition substantially different from the remaining blocks.

[0033] 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, together with substantially the remainder of the ethylene / α-olefin multiblock copolymer containing C3-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.

[0034] 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 greater than 90 wt%, or 95 wt%, or greater than 95 wt%, or greater 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 greater than 5 wt%, or greater than 8 wt%, greater than 10 wt%, or greater than 15 wt% based on the weight of the polymer. In one embodiment, the comonomer content in the soft segments is greater than 20 wt%, greater than 25 wt%, greater than 30 wt%, greater than 35 wt%, greater than 40 wt%, greater than 45 wt%, greater than 50 wt%, or greater than 60 wt%, and can be up to 100 wt%.

[0035] The soft segment may be present in the ethylene / α-olefin multi-block copolymer in an amount of 1 wt% to 99 wt% of the total weight of the ethylene / α-olefin multi-block 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 multi-block 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.

[0036] An ethylene / α-olefin multiblock copolymer contains two or more chemically distinct regions or segments (referred to as "blocks") that are joined linearly (or covalently), i.e., it contains chemically distinguishable units that are joined end-to-end with respect to the polymerized ethylenic functionality, rather than being pendant or grafted. In one embodiment, the blocks differ in the amount or type of comonomer incorporated, density, amount of crystallinity, microcrystalline size that may result from a polymer of such composition, type or degree of stereoregularity (isotactic or syndiotactic), regioregularity or regiomrandomness, 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 both a unique distribution of the polymer polydispersity (PDI or Mw / Mn or MWD), a polydisperse block length distribution, and / or a polydisperse block number distribution due to the effect of a shuttle agent in combination with a plurality of catalysts used in their preparation.

[0037] 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.

[0038] Furthermore, the ethylene / α-olefin multi-block copolymer has a PDI (or Mw / Mn) that conforms to the Schultz-Flory distribution rather than the Poisson distribution. This ethylene / α-olefin multi-block 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.

[0039] In one embodiment, this ethylene / α-olefin multi-block copolymer has a most probable distribution of block lengths.

[0040] In a further embodiment, the ethylene / α-olefin multi-block copolymer of the present disclosure, particularly those 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 multi-block 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. When less than 5 percent of the polymer has an identifiable 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 as follows: Re > 1481 - 1629(d), 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 whole 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.

[0041] The ethylene / α-olefin multiblock copolymer may also have the following: (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.

[0042] It is understood that the ethylene / α-olefin multiblock copolymer may have one, several, all, or any combination of the characteristics (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 analytical methods for determining the characteristics (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.

[0043] In one embodiment, the ethylene / α-olefin multiblock copolymer has a hard segment and a soft segment, is styrene-free, and 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 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 120 °C to 125 °C, or 130 °C, or 135 °C.

[0044] 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 characteristics: (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 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 segment, 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 segment, 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).

[0045] 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).

[0046] Ethylene / α-olefin multiblock copolymers 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 column 16, line 39 to column 19, line 44. Suitable catalysts are described from column 19, line 45 to column 46, line 19, and suitable cocatalysts are described from column 46, line 20 to column 51, line 28. The process is described throughout the document, and in particular, from column 51, line 29 to column 54, line 56. The process is also described, for example, in: U.S. Patent Nos. 7,608,668, 7,893,166, and 7,947,793.

[0047] C. Free radical initiator The crosslinkable polymer composition from which the extruded profile is formed 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), isopropylcumyl 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-dimethylhexyne-3, 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane, isopropylcumyl cumyl peroxide, butyl 4,4-di(tert-butylperoxy)valerate, di(isopropylcumyl) peroxide, dicumyl peroxide, and combinations thereof.

[0048] In one embodiment, the free radical initiator is dicumyl peroxide.

[0049] D.BiTEMPS methacrylate The crosslinkable polymer composition from which the extruded profile is formed 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.

[0050] [Chemical formula]

[0051] In one embodiment, the crosslinkable composition comprises 70 wt% to 98.5 wt%, or 77 wt% to 98.5 wt% of an ethylene polymer, 0.1 wt% to 10 wt%, or 0.1 wt% to 5 wt%, or 0.1 wt% to 3.0 wt%, or 0.1 wt% to 1.5 wt%, or 0.5 wt% to 1.5 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%, or 2 wt% to 20 wt%, or 2 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.

[0052] The crosslinked composition of the extruded profile is formed from the crosslinkable polymer composition. The crosslinkable polymer composition is melt blended at a temperature of 100°C to 250°C, or from 120°C to 210°C, or from 140°C to 210°C, or from 140°C to 190°C to cause a crosslinking reaction and form the 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.

[0053] [Chemical formula]

[0054] 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.

[0055] In one embodiment, the ethylene-based polymer is an unused ethylene-based polymer. As used herein, "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 G' at 140 °C that is greater than the storage modulus value E' of the unused ethylene-based polymer at 140 °C, and (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, and (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, and is formed into an extruded profile as disclosed above.

[0056] In one embodiment, the crosslinked composition comprises 80 wt% to 99.9 wt%, or 80 wt% to 97 wt% of an ethylene-based polymer and a bond having structure (2) formed from (2 wt% to 20 wt% of BiTEMPS methacrylate), and the aggregate of the ethylene-based polymer and the bond of structure (2) (and optional additives) makes up 100 wt% of the crosslinked composition. The crosslinked composition of the extruded profile is (i) a storage modulus value G' at 60°C greater than 1 MPa, and (ii) a storage modulus value G' at 140°C greater than 0.1 MPa, and (iii) a tan delta value at 60°C less than 0.17, and (iv) a tan delta value at 140°C less than 0.62.

[0057] E. Blend Components In one embodiment, the crosslinkable polymer 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), polypentene-1, polyhexene-1, polyoctene-1, polydecene-1, poly-3-methylbutene-1, poly-4-methylpentene-1, polyisoprene, polybutadiene, poly-1,5-hexadiene, interpolymers derived from olefins, interpolymers derived from olefins and other polymers such as polyvinyl chloride, polystyrene, polyurethane, etc., and mixtures thereof.

[0058] 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).

[0059] 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.

[0060] F. Additives The crosslinkable polymer composition and / or the crosslinked composition may contain one or more optional additives. Non-limiting examples of suitable additives include graft initiators, crosslinking catalysts, blowing agents, blowing agent activators (e.g., zinc oxide, zinc stearate, etc.), co-agents (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.

[0061] 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 through 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" which is a temperature of 160°C to 230°C, or 160°C to 200°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.

[0062] The dynamic crosslinking agent BiTEMPS methacrylate enables periodic “reprocessing” for the secondary fabrication of new polymer articles. When the crosslinked ethylene-based polymer composition is heated to the reprocessing temperature, the disulfide bonds are broken or otherwise cleaved, allowing the previously crosslinked ethylene-based polymer composition to flow at the reprocessing temperature and forming a “reprocessable ethylene-based polymer composition”. Heating to the reprocessing temperature allows bond breakage and polymer chain flow, enabling 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 shaping 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 newly crosslinked ethylene-based composition with the high viscosity (non-flowing at room temperature) and resistance to mechanical deformation characteristic of a 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 newly 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 newly crosslinked ethylene-based polymer composition exhibits the high viscosity and resistance to mechanical deformation characteristic of a crosslinked network. This cycle of crosslinking / reprocessing / recrosslinking and secondary processing into new articles can be repeated.

[0063] 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 viscosity after reprocessing to the 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.

[0064] 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 is visual observation. 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.

[0065] G. Process The present disclosure provides a process. In one embodiment, the process includes heating a first article to a reprocessing temperature. The first article is composed of an extrudate or is otherwise an extrudate. The extrudate is composed of a crosslinked composition comprising an ethylene-based polymer and a bond having structure (2) formed from (2,2,6,6-tetramethyl-4-piperidyl methacrylate disulfide (BiTEMPS methacrylate)). The process includes forming the first article into a reprocessable ethylene-based polymer composition at the reprocessing temperature. The process includes shaping the reprocessable ethylene-based polymer composition into a reprocessed preform at the reprocessing temperature. The process includes cooling the reprocessed preform to below the reprocessing temperature to form a second article composed of (i) an ethylene-based polymer and (ii) a re-crosslinked ethylene-based polymer composition composed of BiTEMPS methacrylate.

[0066] The second article may be the same as or different from the first article.

[0067] In one embodiment, the forming process is a procedure selected from the group consisting of injection molding, extrusion, extrusion molding, thermoforming, slush molding, overmolding, insert molding, blow molding, cast molding, tentering, compression molding, and combinations thereof.

[0068] Non-limiting examples of a second article suitable for the present crosslinked / re-crosslinked ethylene-based polymer (including BiTEMPS methacrylate) composition include three-dimensional loop materials, extruded profiles, 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 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, liners, cap liners, flooring materials, and combinations thereof.

[0069] The applicant has discovered an extruded profile that can undergo reversible crosslinking at the reprocessing temperature. This is achieved by forming an extruded profile from a crosslinkable polymer composition of an ethylene-based polymer, a peroxide, and BiTEMPS methacrylate. The composition of the present invention forms an article composed of an extruded profile composed of a crosslinked composition or is otherwise an extruded profile composed of a crosslinked composition, the crosslinked composition being crosslinked at the intended use temperature but capable of being melt reprocessed at typical extruded profile processing temperatures (about 160 - 250 °C). As a result, the proposed solution provides the advantages of heat resistance and durability of the extruded profile while maintaining the (re)processability at typical extrusion temperatures.

[0070] By way of example and not limitation, several embodiments of the present disclosure will now be described in detail in the following examples.

[0071] 1. Materials The materials used in the comparative sample (CS) and the inventive example (IE) of the present invention are provided in Table 1 below.

[0072]

Table 1

[0073] 2. 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) was 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) was dissolved in anhydrous petroleum ether (about 1.25 mL) and added dropwise to the reaction vessel over 30 minutes. The solution was stirred at - 70 °C for an additional 30 minutes and at room temperature for 15 minutes. Next, the reaction solution was poured into a large amount of distilled water and stirred at room temperature overnight to precipitate BiTEMPS methacrylate. The precipitate was collected, vacuum - filtered, and dried under vacuum at 60 °C for 48 hours to obtain BiTEMPS methacrylate shown as Structure 1 below.

[0074]

Chemical Formula

[0075] 3. Formulation Composition (i) Baseline polyethylene (8842, 9000, 8100), (ii) polyethylene and DCP, and (iii) polyethylene, DCP, and BiTEMPS methacrylate were combined (in the amounts shown in Table 2 below) and batch - mixed at 100 °C to form a cross - linkable polymer composition. The cross - linkable polymer composition was heated on an RPA at 160 °C for 60 minutes to initiate the cross - linking reaction. The properties of the cross - linked composition are provided in Table 2 below.

[0076] [Table 2] * Compositions having a VRR greater than 5 are recyclable. Compositions having a VRR less than 5 are not recyclable.

[0077] 4. Crosslinking A 4 inch × 3 inch × 1.5 mm or 1 inch diameter plaque and a 0.5 inch thick button of the crosslinking composition were prepared in a compression molding machine at 30,000 lbf and 180 °C for 15 minutes. The plaque and button were then conditioned at room temperature for 1 day. Tensile tests at 80 °C, compression set at 70 °C, and compression set at 100 °C were evaluated as reported in Table 2.

[0078] [Table 3]

[0079] Table 3 summarizes the RPA results and indicates whether the material was crosslinked based on the RPA S’ value and whether the crosslinking composition was recyclable based on the VRR (i.e., viscosity ratio, VRR = RPA n at 160 °C * (0.1) / RPA n at 230 °C * (0.1)). A high RPA S’ value was an indicator that the composition during the initial curing process could reach a crosslinked state. The observation of high S’ values in Table 2 was also found to be consistent with the measured physical properties of the crosslinked material, including high tensile strength at 80 °C and relatively low Cset at 70 °C and 100 °C compared to the uncrosslinked elastomer.

[0080] A high VRR (greater than 5) is required to reprocess the crosslinked material during extrusion or to be reprocessable otherwise. This is due to the fact that the viscosity of irreversible crosslinked materials (compositions containing DCP and not containing BiTEMPS) at processing temperatures such as 230 °C typically experiences a viscosity reduction low enough to be extrudable. However, Examples IE1 - IE4 of the present invention each exhibit a significant viscosity reduction - at least a 5-fold reduction at 230 °C (i.e., VRR > 5) due to the breaking of disulfide bonds, and thus, IE1 - IE4 are extrudable and reprocessable.

[0081]

Table 4

[0082] For the extrusion study, the crosslinked plaques were cut into small pieces using scissors. Small pieces of each 20-gram crosslinked composition were fed into a microcompounder (DSM EXPLORE Microcompounder MC40) operating at 200 °C - 230 °C, starting at 25 rpm and increasing to 50 rpm if possible. The extrusion conditions and observations are shown in Table 4.

[0083] In Table 4, the extrudability of IE2 and IE4 was confirmed, and each example of the present invention after crosslinking (i.e., IE2 and IE4 after curing at 180 °C for 15 minutes) was able to be extruded at temperatures of 200 - 230 °C. In particular, for the extrusion carried out at 230 °C, the extruder was able to operate up to 50 RPM and had a relatively low torque comparable to that of the ENGAGE 8100 non-crosslinked resin extruded at 200 °C.

[0084] The present disclosure is not limited to the embodiments and examples included herein, and is particularly intended to include modified forms of those embodiments, including parts of embodiments and combinations of elements of different embodiments, to the extent that they fall within the scope of the following claims.

Claims

1. An article comprising an ethylene polymer and a crosslinked composition formed from starting materials including 2,2,6,6 - tetramethyl - 4 - piperidyl methacrylate disulfide (BiTEMPS methacrylate), the article comprising an extruded profile composed of the crosslinked composition.

2. The article according to claim 1, wherein the crosslinked composition comprises a bond of Structure 2 【Chemical 1】 .

3. The article according to claim 1 or 2, wherein the crosslinked composition comprises 80 wt% to 99 wt% of an ethylene polymer having a melt index of 0.1 g / 10 min to 100 g / 10 min and 20 wt% to 1 wt% of the BiTEMPS methacrylate.

4. The article according to any one of claims 1 to 3, wherein the ethylene 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.

5. The article according to any one of claims 1 to 4, wherein the ethylene polymer is the unused ethylene polymer before the crosslinked composition is crosslinked, and the crosslinked composition has (i) a storage modulus value G' at 140 °C greater than the storage modulus value G' of the unused ethylene polymer at 140 °C, (ii) a tan delta value at 60 °C less than the tan delta value of the unused ethylene polymer at 60 °C, and (iii) a tan delta value at 140 °C less than the tan delta value of the unused ethylene polymer at 140 °C.

6. An article comprising an ethylene polymer and a bond having Structure 2 【Chemical Formula 2】 , the article comprising an extruded profile composed of a crosslinked composition containing the same.

7. A process comprising heating a first article, the first article comprising (i) an ethylene polymer and (ii) an extruded profile composed of a crosslinked composition containing a bond of Structure 2, to a reprocessing temperature; 【Chemical 3】 forming the first article at the reprocessing temperature into a reprocessable ethylene - based polymer composition; and forming the reprocessable ethylene - based composition at the reprocessing temperature into a reprocessed preform. Cool the reprocessed preform to below the reprocessing temperature and form a second article composed of (i) the ethylene-based polymer and (ii) a re-crosslinked ethylene-based polymer composition composed of the bond having the structure 2. A process comprising:

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