Thermally cross-linked ethylene-based polymer

Abstract

Embodiments are directed to a thermally cross-linked ethylene-based polymer comprising an ethylene-based polymer formed by high pressure (greater than or equal to 100 MPa and less than or equal to 400 MPa), free-radical polymerization of ethylene and one or more cyclicvinylsiloxane molecules. Each of the one or more cyclicvinylsiloxane molecules comprises two or more vinyl groups. The thermally cross-linked ethylene-based polymer, thermally cross-linked in the presence of oxygen, has a greater melt elongation relative to an ethylene-based polymer not subjected thermal crosslinking in the presence of oxygen. Further embodiments are directed to a process for making the thermally cross-linked ethylene-based polymer.

Description

[0001] 86400-WO-PCT / DOW 86400 WO

[0002] 1

[0003] THERMALLY CROSS-LINKED ETHYLENE-BASED POLYMER

[0004] CROSS-REFERENCE TO RELATED APPLICATIONS

[0005] [1] This application claims the benefit of U.S. Provisional Application Serial No. 63 / 725,673 filed November 27, 2024, the contents of which are incorporated in their entirety herein.

[0006] TECHNICAL FIELD

[0007] [2] Embodiments of the present disclosure generally relate to ethylene-based polymers and specifically relate to thermally cross-linked ethylene-based polymers.

[0008] BACKGROUND

[0009] [3] High-pressure reactors have been used in industry for making low density polyethylene (LDPE) products for many years. The level of branching in LDPE at given melt index correlates to melt elongation, with higher branching correlating to a higher melt elongation. The level of branching in LDPE is affected by the reactor design and the polymerization conditions used to make the LDPE. But the process conditions required to achieve LDPE with a high level of branching, and thus high melt elongation may result in a final product with a lower crystallinity and with a higher content of a low molecular weight extractable fraction. Branching agents have been used to increase the level of branching in an LDPE under conditions that maintain desirable polymer properties. However, due to processing limitations, only a limited amount of branching agent may be added, thereby limiting the melt elongation increase that may be achieved.

[0010] [4] Accordingly, there is a need for a modified LDPE having relatively higher branching levels corresponding to a relatively higher melt elongation as compared to a LDPE formed utilizing a branching agent.

[0011] SUMMARY

[0012] [5] The embodiments of the present disclosure meet this need by utilizing thermal crosslinking in the presence of oxygen. This resulted in a thermally cross-linked ethylenebased polymer having a greater melt elongation (e.g., at least 5% greater) relative to an ethylene-based polymer not subjected thermal crosslinking in the presence of oxygen. 86400-WO-PCT / DOW 86400 WO

[0013] 2

[0014] [6] In one embodiment, a thermally cross-linked ethylene-based polymer comprises an ethylene-based polymer formed by high pressure (greater than or equal to 100 MPa and less than or equal to 400 MPa), free-radical polymerization of ethylene and one or more cyclicvinylsiloxane based molecules. Each of the one or more cyclicvinylsiloxane molecules comprises two or more vinyl groups. The thermally cross-linked ethylene-based polymer, thermally cross-linked in the presence of oxygen, has a greater melt elongation relative to an ethylene-based polymer not subjected thermal crosslinking in the presence of oxygen.

[0015] [7] In another embodiment, a process for making a thermally cross-linked ethylenebased polymer comprises producing an ethylene-based polymer by high pressure (greater than or equal to 100 MPa and less than or equal to 400 MPa), free-radical polymerization of ethylene and one or more cyclicvinylsiloxane based molecules and crosslinking the ethylenebased polymer with heat in the presence of oxygen for a duration of at least 10 minutes to form the thermally cross-linked ethylene-based polymer. Each of the one or more cyclicvinylsiloxane molecules comprises two or more vinyl groups. The thermally crosslinked ethylene-based polymer has a greater melt elongation relative to an ethylene-based polymer not subjected thermal crosslinking.

[0016] [8] Additional features and advantages will be set forth in the detailed description, which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows and the claims.

[0017] [9] It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter.

[0018] DETAILED DESCRIPTION

[0019]

[0010] Specific embodiments of the present application will now be described. The disclosure may be embodied in different forms and should not be construed as limited to the embodiments set forth in this disclosure. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the subject matter to those skilled in the art.

[0020]

[0011] DEFINITIONS 86400-WO-PCT / DOW 86400 WO

[0021] 3

[0022]

[0012] Unless stated to the contrary, implicit from the context, or customary in the art, all test methods are current as of the filing date of this disclosure.

[0023]

[0013] Ranges may be expressed herein as from “about” one particular value, and / or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and / or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about,” it will be understood that the particular value forms another embodiment. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint.

[0024]

[0014] The terms "comprising", "including", "having”, and their derivatives, are not intended to exclude the presence of any additional component, step or procedure, whether the same is specifically disclosed. In order to avoid any doubt, all compositions claimed through use of the term "comprising" may include any additional additive, adjuvant, or compound, whether polymeric or otherwise, unless stated to the contrary. In contrast, the term, "consisting essentially of’ excludes from the scope of any succeeding recitation any other component, step or procedure, excepting those that are not essential to operability. The term "consisting of’ excludes any component, step or procedure, not specifically delineated or listed.

[0025]

[0015] Unless stated to the contrary, implicit from the context, or customary in the art, all parts and percentages are based on weight.

[0026]

[0016] The term "ethylene monomer," as used herein, refers to a chemical unit having two carbon atoms with a double bond there between, and each carbon bonded to two hydrogen atoms, wherein the chemical unit polymerizes with other such chemical units to form an ethylene-based polymer composition.

[0027]

[0017] The term “LDPE” may also be referred to as “high-pressure ethylene polymer” or “highly branched polyethylene” and is defined to mean that the polymer is partly or entirely homopolymerized or copolymerized in autoclave or tubular reactors high pressure (greater than or equal to 100 MPa and less than or equal to 400 MPa) with the use of free-radical initiators, such as peroxides (see, for example, U.S. Patent No. 4,599,392, which is hereby incorporated by reference in its entirety). LDPE resins typically have a density in the range of 0.916 g / cm3to 0.930 g / cm3. 86400-WO-PCT / DOW 86400 WO

[0028] 4

[0029]

[0018] The term "cyclicvinylsiloxane molecules comprising two or more vinyl groups," (or interchangeably referred to as "cyclicvinylsiloxane molecules") as used herein, refers to a chemical component that is a cyclic siloxane where cycle composed of alternating silicon and oxygen atoms, having two or more vinyl groups that are attached directly to silicon atoms.

[0030]

[0019] The term "mixture of cyclicvinylsiloxane molecules," as used herein, refers to two or more cyclicvinylsiloxane molecules, wherein at least two of the molecules differ in structure, property, and / or composition.

[0031]

[0020] The term “thermally cross-linked ethylene-based polymer,” as used herein, refers to a polymer that has been thermally cross-linked in the presence of oxygen.

[0032]

[0021] The terms “crosslinking,” “thermal crosslinking,” and “thermal treatment,” as used herein, refer to crosslinking with heat in the presence of oxygen.

[0033]

[0022] EMBODIMENTS

[0034]

[0023] Embodiments of the present disclosure are directed to thermally cross-linked ethylene-based polymers comprising an ethylene-based polymer formed by high pressure (greater than or equal to 100 MPa and less than or equal to 400 MPa), free-radical polymerization of ethylene and one or more cyclicvinylsiloxane molecules.

[0035]

[0024] Ethylene-based Polymer

[0036]

[0025] The ethylene-based polymer is the polymerization reaction product of ethylene and one or more cyclicvinylsiloxane molecules. Each cyclicvinylsiloxane molecule comprise two or more vinyl groups.

[0037]

[0026] In embodiments, each of the cyclicvinylsiloxane molecules (i.e., one or more of the cyclicvinylsiloxane molecules) may comprise Structure I:

[0038] Structure I

[0039]

[0027] In Structure I, n may be from 2 to 4; Ri, R2, R3, and R4 may each independently H, an alkyl group, an aryl group, a cycloalkyl group, an alkoxy group, or a vinyl group; and at least 2 of Ri, R2, R3, or R4 may be a vinyl group. 86400-WO-PCT / DOW 86400 WO

[0040] 5

[0041]

[0028] In embodiments, referring to Structure I, n may be 3, Ri and R3 may be a vinyl group, and R2 and R4 may be a methyl group such that the cyclicvinylsiloxane comprises Structure II:

[0042]

[0029] Structure II may be referred to as 2,4,6,8-tetramethyl-2,4,6,8- tetravinylcyclotetrasiloxane (ViD4).

[0043]

[0030] In embodiments, the ethylene-based polymer may comprise, in polymerized form, from 95 wt% to 99.95 wt%, from 95 wt% to 99.90 wt%, from 96 wt% to 99.95 wt%, from 96 wt% to 99.0- wt%, from 97 wt% to 99.95 wt%, from 97 wt% to 99.90 wt%, from 98 wt% to 99.95 wt%, from 98 wt% to 99.90 wt%, or any subset thereof, of ethylene, and a reciprocal amount of the cyclicvinylsiloxane, or from 0.05 wt% to 5 wt%, from 0.05 wt% to 4 wt%, from 0.05 wt% to 3 wt%, from 0.05 wt% to 2 wt%, from 0.1 wt% to 5 wt%, from 0.1 wt% to 4 wt%, from 0.1 wt% to 3 wt%, from 0.1 wt% to 2 wt%, from 0.5 wt% to 5 wt%, from 0.5 wt% to 4 wt%, from 0.5 wt% to 3 wt%, from 0.5 wt% to 2 wt%, from 1 wt% to 5 wt%, from 1 wt% to 4 wt%, from 1 wt% to 3 wt%, from 1 wt% to 2 wt%, or any subset thereof. Weight percent is based on total weight of the ethylene-based polymer.

[0044]

[0031] In embodiments, the ethylene-based polymer may have a density from 0.910 g / cc to 0.940 g / cc, from 0.910 g / cc to 0.935 g / cc, from 0.910 g / cc to 0.930 g / cc, from 0.910 g / cc to 0.925 g / cc, from 0.914 g / cc to 0.940 g / cc, from 0.914 g / cc to 0.935 g / cc, from 0.914 g / cc to 0.930 g / cc, from 0.914 g / cc to 0.925 g / cc, or any subset thereof.

[0045]

[0032] In embodiments, the ethylene-based polymer may have a melt index (h), prior to thermal crosslinking, from 0.05 g / 10 min to 200 g / 10 min, from 0.10 g / 10 min to 150 g / 10 min, from 0.10 g / 10 min to 50 g / 10 min, from 0.1 g / 10 min to 10 g / 10 min, from 0.15 g / 10 min to 150 g / 10 min, from 0.15 g / 10 min to 10 g / 10 min, from 0.25 g / 10 min to 150 g / 10 min, from 0.25 g / 10 min to 10 g / 10, or any subset thereof. 86400-WO-PCT / DOW 86400 WO

[0046] 6

[0047]

[0033] In embodiments, the ethylene-based polymer may have an alkenes content from 0.05 / 1000 carbons to 3.0 / 1000 carbons, from 0.05 / 1000 carbons to 2.0 / 1000 carbons, from 0.05 / 1000 carbons to 1.0 / 1000 carbons, from 0.15 / 1000 carbons to 3.0 / 1000 carbons, from 0.15 / 1000 carbons to 2.0 / 1000 carbons, from 0.15 / 1000 carbons to 1.0 / 1000 carbons, from 0.3 / 1000 carbons to 3.0 / 1000 carbons, from 0.3 / 1000 carbons to 2.0 / 1000 carbons, from 0.3 / 1000 carbons to 1.0 / 1000 carbons, from 0.4 / 1000 carbons to 3.0 / 1000 carbons, from 0.4 / 1000 carbons to 2.0 / 1000 carbons, from 0.4 / 1000 carbons to 1.0 / 1000 carbons, or any subset thereof.

[0048]

[0034] In embodiments, the ethylene-based polymer may be a low density polyethylene comprising, in polymerized form, ethylene monomer and the cyclicvinylsiloxane molecules.

[0049]

[0035] The ethylene-based polymer is produced via in-reactor high pressure (greater than or equal to 100 MPa and less than or equal to 400 MPa), free-radical polymerization of ethylene and cyclicvinylsiloxane. An exemplary process of making the ethylene-based polymer is described in International Patent Application Publication No. WO 2020 / 112873, which is incorporated herein by reference in its entirety.

[0050]

[0036] In an embodiment, the ethylene-based polymer composition includes a blend component. The blend component is a polymer that does not include the mixture of cyclicvinylsiloxane molecules.

[0051]

[0037] In an embodiment, the blend component is an ethylene-based polymer that does not include the mixture of the cyclicvinylsiloxane molecules. Nonlimiting examples of suitable ethylene-based polymers include only ethylene based polymers like, for example, LDPE or HDPE, ethylene / alpha-olefin copolymers, ethylene / C3-C8 alpha-olefin copolymers, ethylene / C4-C8 alpha-olefin copolymers, and copolymers of ethylene and one or more of the following comonomers: (meth)acrylic acid, (meth)acrylic ester, carbon monoxide, maleic anhydride, vinyl acetate, vinyl propionate, mono esters of maleic acid, diesters of maleic acid, vinyl trialkoxysilane, vinyl trialkyl silane, and any combination thereof.

[0052]

[0038] Thermally Cross-linked Ethylene-based Polymer

[0053]

[0039] As described herein, the thermally cross-linked ethylene-based polymer has a greater melt elongation relative to the ethylene-based polymer not subjected to thermal crosslinking.

[0054]

[0040] In embodiments, the melt elongation of the of the thermally cross-linked ethylenebased polymer may be at least 5% greater, at least 10% greater, at least 25% greater, at least 86400-WO-PCT / DOW 86400 WO

[0055] 7

[0056] 50% greater, at least 75% greater, or even at least 100% greater than the ethylene-based polymer not subjected to thermally crosslinking in the presence of oxygen.

[0057]

[0041] In embodiments, the melt elongation of the of the thermally cross-linked ethylenebased polymer may be at least 2 nm greater, at least 5 nm greater, at least 10 nm greater, at least 25 nm greater, at least 50 nm greater, at least 75 nm greater, or even at least 100 nm greater than the ethylene-based polymer not subjected to thermally crosslinking in the presence of oxygen.

[0058]

[0042] In embodiments, the thermally cross-linked ethylene-based polymer may have a melt elongation greater than or equal to 20 mN, greater than or equal to 40 mN, greater than or equal to 60 mN, greater than or equal to 80 nM, greater than or equal to 100 mN, greater than or equal to 120 mN, or even greater than or equal to 140 mN.

[0059]

[0043] While not wishing to be bound by theory, relatively greater melt elongation is indicative of enhanced mechanical properties, dimensional stability, and heat resistance. For example, higher melt elongation may indicate better molecular alignment and packing during the molding process, leading to improved mechanical properties, such as tensile strength, impact resistance, and rigidity. Moreover, rigid articles may need to maintain their shape and dimensions under various conditions. Increased melt elongation may help in achieving a better dimensional stability, reducing warping and deformation. Furthermore, rigid applications may rely on materials that can withstand higher temperatures without losing structural integrity. Increased melt elongation may contribute to better heat resistance, making the material more suitable for demanding environments.

[0060]

[0044] One skilled in the art should appreciate that melt index (I2) correlates to melt elongation, lower melt index (I2) corresponding to greater the melt elongation. However, while not wishing to be bound by theory, after a given thermal crosslinking, the melt index (I2) of the thermally cross-linked, ethylene-based polymer may begin to increase.

[0061]

[0045] The thermally cross-linked ethylene-based polymer may be used to form various articles, including monolayer and multilayer films; molded articles, such as blow molded, injection molded, or rotomolded articles; coatings; fibers; and woven or non- woven fabrics, cables, pipes, green house films, silo bag films, collation shrink films, food packaging films, or foams.

[0062]

[0046] Process for Making Thermally Cross-linked Ethylene-based Polymer 86400-WG-PCT / DGW 86400 WO

[0063] 8

[0064]

[0047] In embodiments, a process for making a thermally cross-linked ethylene-based polymer comprises producing an ethylene-based polymer and crosslinking the ethylene-based polymer with heat in the presence of oxygen for a duration and at a temperature

[0065]

[0048] The ethylene-based polymer may be produced by high pressure (greater than or equal to 100 MPa and less than or equal to 400 MPa), free-radical polymerization of ethylene and one or more cyclicvinylsiloxane molecules, as described herein.

[0066]

[0049] In embodiments, the crosslinking may comprise heating the ethylene-based polymer in the presence of oxygen. Heat and oxygen promote crosslinking, thereby achieving the desired increase in melt elongation. In embodiments, the ethylene-based polymer may be formed into an article (e.g., polymer pellets) prior to thermal treatment. In embodiments, the crosslinking may occur in ambient air (i.e. 21% oxygen). In embodiments, the crosslinking may occur in little to no light, such as in a dark convection oven.

[0067]

[0050] In embodiments, the crosslinking may occur at a temperature greater than or equal to 40 °C, greater or equal to 60 °C, greater or equal to 80 °C, or even greater or equal to 100 °C.

[0068]

[0051] In embodiments, the crosslinking may occur for a duration greater than or equal to 10 minutes, greater than or equal to 20 minutes, greater than or equal to 30 minutes, or even greater or equal to 60 min.

[0069]

[0052] One skilled in the art would appreciate that temperature and / or duration may be altered to effect crosslinking. Relatively higher temperatures for relatively short durations or relatively low temperature for relatively long durations may both produce the desired crosslinking.

[0070]

[0053] In embodiments, the crosslinking does not include any additional reagents or catalysts, such as silane or peroxide crosslinker.

[0071]

[0054] TEST METHODS

[0072]

[0055] Melt Elongation

[0073]

[0056] “Melt elongation,” as used herein, refers to the measure of the maximum tension applied to a polymer in a melted state, before the polymer breaks. Melt elongation is measured using a GOTTFERT D-Melt instrument (GOTTFERT Werkstoff-Prufmaschinen GmbH, SiemensstraBe 2, 74722 Buchen, Germany). A molten polymer strand is extruded from a standard plastometer barrel at a constant temperature (190 °C) through a standard ASTM D1238 MFR die orifice (height (8.000 ± 0.025 mm) and diameter (2.0955 ± 0.005 86400-WO-PCT / DOW 86400 WO

[0074] 9 mm)) using a weighted piston. The extrudate is pulled through 2 free spinning rollers onto a drum driven by a stepper motor which is ramped over a velocity range during the analysis. The force of the polymer strand pulling up on the force sensor platform mounted tension roller is recorded by the integrated control computer. From a curve fitting function of the acquired force data, the final reported melt elongation value is determined based on a constant velocity ratio of the polymer strand speed versus the die exit speed. Measurement results are reported as melt elongation in milli-Newton (mN). After the melt elongation measurement, the melt index measurement at ASTM conditions as described below is performed with the same charge.

[0075]

[0057] Melt Index

[0076]

[0058] The terms "melt index," or “h,” as used herein, refer to the measure of how easily a thermoplastic polymer flows when in a melted state. Melt index (I?) is measured in accordance with ASTM D 1238, Condition 190 °C / 2.16 kg, and is reported in grams eluted per 10 minutes (g / 10 min).

[0077]

[0059] EXAMPLES

[0078]

[0060] By way of example, and not limitation, some embodiments of the present disclosure will now be described in detail by the following examples.

[0079]

[0061] Materials

[0080]

[0062] 2,4,6,8-tetramethyltetravinylcyclotetrasiloxane (ViD4) was supplied from MilliporeSigma.

[0081]

[0063] Polymerization: Autoclave Reactor

[0082]

[0064] Inventive Example IE1

[0083]

[0065] For Inventive Example IE1, ViD4 was loaded into a 316 stainless steel supply vessel and diluted with Isopar™ E to produce a final concentration of 1.7 wt%. This vessel was purged with nitrogen for three hours before use and kept under 70 psig nitrogen pad during operation.

[0084]

[0066] Peroxide initiator tert-butyl peroxyacetate (TPA, 20% by weight solution in ISOPAR™ H) and peroxide initiator di-tert-butyl peroxide (DTBP, 20% by weight solution in ISOPAR™ H) were combined with ISOPAR E in a second 316 stainless steel supply vessel to produce 1500 mass ppm TPA and 415 mass ppm DTBP (a ratio of 4:1 mole TPA / mole DTBP). The vessel was padded and de-padded five times with 70 psig nitrogen before use and kept under nitrogen pad during operation. 86400-WO-PCT / DOW 86400 WO

[0085] 10

[0086]

[0067] Ethylene was injected at 5500 gm / hr and at a pressure of 193 MPa into an agitated (1600 rpm) 300 mL high pressure CSTR reactor with an external heating jacket set to control the internal reactor temperature at 220 °C. Propylene (CTA) was added to the ethylene stream at a pressure of 6.2 MPa and controlled at a rate to produce a final product with a MI of about 4 g / 10 min before the mixture was compressed to 193 MPa and injected into the reactor. The solution of the appropriate additive solution was pumped at a pressure of 193 MPa directly into the reactor via a high-pressure pump. The peroxide initiator solution was added directly to the reactor, through the sidewall, at a pressure of 193 MPa at a rate to control the ethylene conversion near 12%.

[0087]

[0068] Comparative Sample CSA

[0088]

[0069] For Comparative Sample CSA, all process conditions were the same as for Inventive Example IE1, except for the Comparative Sample CSA, ViD4 was not added.

[0089]

[0070] Thermal crosslinking in the presence of air

[0090]

[0071] Inventive Example IE1-4 and Comparative Sample CSA were heated in a dark convection oven at 100 °C in ambient conditions for various durations as indicated. The oven was the UT 6060 model of Heraeus Instruments, with valve to control air flow fully open. The pellets were introduced in an aluminum bucket, evenly distributed over the surface in a single layer, and placed in the center of the oven.

[0091]

[0072] The melt elongations (in mN) of Inventive Example IE1 and Comparative Sample CSA, after thermal treatment for the time indicated and the melt elongation increase (in percentage and change), as compared to non-exposure (i.e., time = 0 hours) are shown in Table 1. The melt indices (in g / 10 min) of Inventive Example and Comparative Sample CSA and corresponding melt index change, as compared to non-exposure are also shown in Table 1.

[0092]

[0073] Table 1 86400-WO-PCT / DOW 86400 WO

[0093] 11

[0094] 1Measurement capabilities of machine limited to 150 nM.

[0095]

[0074] As shown in Table 1, after thermal treatment, Inventive Example IE1, a thermally cross-linked ethylene-based polymer including ViD4, had a greater melt force as compared to the sample not exposed to thermal treatment. Indeed, melt forces were so high that they could not be measured.

[0096]

[0075] As also shown in Table 1, after thermal treatment, Inventive Example IE1, a thermally cross-linked ethylene-based polymer including ViD4, had a greater melt force increase as compared to Comparative Sample CSA, thermally cross-linked ethylene-based polymers lacking ViD4, after 24 hrs. at 50 °C and 24 hrs. at 100 °C. A comparison could not be conducted after 48 hrs. at 100 °C do to the limited measurement capabilities of the machine.

[0097]

[0076] While particular embodiments of the present disclosure have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the disclosure. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this disclosure.

Claims

86400-WO-PCT / DOW 86400 WO12CLAIMS1. A thermally cross-linked ethylene-based polymer comprising: ethylene-based polymer formed by high pressure (greater than or equal to 100 MPa and less than or equal to 400 MPa), free-radical polymerization of ethylene and one or more cyclicvinylsiloxane molecules, each of the one or more cyclicvinylsiloxane molecules comprising two or more vinyl groups, wherein the thermally cross-linked ethylene-based polymer, thermally cross-linked in the presence of oxygen, has a greater melt elongation relative to an ethylene-based polymer not subjected thermal crosslinking in the presence of oxygen.

2. The thermally cross-linked ethylene-based polymer of claim 1, wherein each of the one or more cyclicvinylsiloxane molecules comprise Structure I:where n is from 2 to 4; Ri, R2, R3, and R4 are each independently H, an alkyl group, an aryl group, a cycloalkyl group, an alkoxy group, or a vinyl group; and at least 2 of Ri, R2, R3, or R4 is a vinyl group.

3. The thermally cross-linked ethylene-based polymer of claim 2, wherein n is 3, Ri andR3 are a vinyl group, and R2 and R4 are a methyl group such that the cyclicvinylsiloxane comprises Structure II:Structure II86400-WO-PCT / DOW 86400 WO134. The thermally cross-linked ethylene-based polymer of any one of claims 1 to 3, wherein the ethylene-based polymer has an alkenes content from 0.05 / 1000 carbons to 3.0 / 1000 carbons, or from 0.07 / 1000 carbons to 2.0 / 1000 carbons, or from 0.1 / 1000 carbons to 1.2 / 1000 carbons.

5. The thermally cross-linked ethylene-based polymer of any one of claims 1 to 4, wherein the ethylene-based polymer composition is a low density polyethylene comprising, in polymerized form, ethylene monomer and the one or more cyclicvinylsiloxane molecules.

6. The thermally cross-linked ethylene-based polymer of any one of claims 1 to 5, wherein the melt elongation of the thermally cross-linked ethylene-based polymer is at least 5% greater than the ethylene-based polymer not subjected to thermal crosslinking in the presence of oxygen.

7. The thermally cross-linked ethylene-based polymer of any one of claims 1 to 6, wherein the melt elongation of the thermally cross-linked ethylene-based polymer is at least 2 mN greater than the ethylene-based polymer not subjected to thermal crosslinking in the presence of oxygen.

8. The thermally cross-linked ethylene-based polymer of any one of claims 1 to 7, wherein the melt elongation of the thermally cross-linked ethylene-based polymer is greater than or equal to 20 mN.

9. An article comprising the thermally cross-linked ethylene-based polymer of any one of claims 1 to 8.

10. A process for making a thermally cross-linked ethylene-based polymer comprising: producing an ethylene-based polymer by high pressure (greater than or equal to 100MPa and less than or equal to 400 MPa), free-radical polymerization of ethylene and one or more cyclicvinylsiloxane molecules, each of the one or more cyclicvinylsiloxane molecules comprising two or more vinyl groups; and86400-WO-PCT / DOW 86400 WO14 crosslinking the ethylene-based polymer with heat in the presence of oxygen for a duration of at least 10 minutes to form the thermally cross-linked ethylene-based polymer, wherein the thermally cross-linked ethylene-based polymer has a greater melt elongation relative to an ethylene-based polymer not subjected to thermal crosslinking in the presence of oxygen.

11. The process of claim 10, wherein the crosslinking does not include silane or peroxide crosslinker.

12. The process of claim 10 or claim 11, wherein the crosslinking occurs at a temperature greater than or equal to 40 °C.

13. The process of any one of claims 10 to 12, wherein the melt elongation of the thermally cross-linked ethylene-based polymer is at least 5% greater than the ethylene-based polymer not subjected to thermal crosslinking in the presence of oxygen.

14. The process of any one of claims 10 to 13, wherein the melt elongation of the thermally cross-linked ethylene-based polymer is at least 2 mN greater than the ethylene-based polymer not subjected to thermal crosslinking in the presence of oxygen.

15. The process of any one of claims 10 to 14, wherein the melt elongation of the thermally cross-linked ethylene-based polymer is greater than or equal to 20 mN.

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