Polymers of Ethylene and Monocyclic Organosiloxane

Abstract

An ethylene-based polymer composition includes units derived from ethylene, units derived from a comonomer, and an optionally units derived from a termonomer. The comonomer is a monocyclic organosiloxane (MOCOS) of formula (I) [R.sup.1, R.sup.2SiO.sub.2/2].sub.n wherein n is an integer greater than or equal to 3, each R.sup.1 is independently a (C.sub.2-C.sub.4) alkenyl or a H.sub.2C═C(R.sup.1a)—C(═O)—O—(CH.sub.2).sub.m— wherein R.sup.1a is H or methyl, m is an integer from 1 to 4, and each R.sup.2 is independently H, (C.sub.1-C.sub.4) alkyl, phenyl, or R.sup.1.

Claims

1. An ethylene-based polymer composition comprising: units derived from ethylene, units derived from a comonomer, and an optionally units derived from a termonomer; and the comonomer is a monocyclic organosiloxane (MOCOS) of formula (I)
[R.sup.1,R.sup.2SiO.sub.2/2].sub.n wherein n is an integer greater than or equal to 3, each R.sup.1 is independently a (C.sub.2-C.sub.4)alkenyl or a H.sub.2C═C(R.sup.1a)—C(═O)—O—(CH.sub.2).sub.m— wherein R.sup.1a is H or methyl; m is an integer from 1 to 4; and each R.sup.2 is independently H, (C.sub.1-C.sub.4)alkyl, phenyl, or R.sup.1.

2. The ethylene-based polymer composition of claim 1 comprising from 0.01 wt % to 0.5 wt % of the MOCOS comonomer.

3. The ethylene-based polymer composition of claim 1 wherein the MOCOS comonomer is selected from the group consisting of 2,4,6-trimethyl-2,4,6-trivinyl-cyclotrisiloxane, 2,4,6,8-tetramethyl-2,4,6,8-tetravinyl-cyclotetrasiloxane, 2,4,6,8,10-pentamethyl-2,4,6,8,10-pentavinyl-cyclopentasiloxane, and combinations thereof.

4. The ethylene-based polymer of claim 1 wherein the ethylene-based polymer is an ethylene/MOCOS copolymer having (i) a Mw/Mn from 7.5 to 9.5, (ii) a vinyls content from 0.3600/1000 carbons to 0.6200/1000 carbons, and (iii) a trans content from 0.1000/1000 carbon atoms to 0.3100/1000 carbon atoms.

5. The ethylene-based polymer of claim 1 wherein the ethylene/MOCOS copolymer has (iv) an MI from 2.0 g/10 min to 5.0 g/10 min, and (v) a melt strength from 5.0 to 8.5 cN.

6. The ethylene-based polymer composition of claim 1 wherein the termonomer is present and is selected from the group consisting of an olefin, an unsaturated ester, a functionalized alkene, and combinations thereof.

7. The ethylene-based polymer of claim 6 wherein the ethylene-based polymer comprises from 0.01 wt % to 0.5 wt % of the MOCOS comonomer; and from 0.5 wt % to 20 wt % of the termonomer.

8. An article comprising the ethylene-based polymer composition of claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0066] FIG. 1 is a graph showing melt force (MF) versus weight percent of MOCOS present in the formant ethylene/MOCOS copolymer in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

[0067] The present disclosure is directed to an ethylene-based polymer composition. In an embodiment, the ethylene-based polymer composition includes units derived from ethylene, units derived from a comonomer, and an optionally units derived from a termonomer. The comonomer is a monocyclic organosiloxane (MOCOS) of formula (I)

[R.sup.1,R.sup.2SiO.sub.2/2].sub.n

[0068] wherein n is an integer greater than or equal to 3,

[0069] each R.sup.1 is independently a (C.sub.2-C.sub.4)alkenyl or a H.sub.2C═C(R.sup.1a)—C(═O)—O—(CH.sub.2).sub.m—

[0070] wherein R.sup.1a is H or methyl,

[0071] m is an integer from 1 to 4, and

[0072] each R.sup.2 is independently H, (C.sub.1-C.sub.4)alkyl, phenyl, or R.sup.1.

[0073] The ethylene-based polymer composition includes (i) units derived from ethylene, (ii) units derived from comonomer (hereafter interchangeably referred to as “ethylene/MOCOS copolymer”), and (iii) optionally units derived from a termonomer (hereafter interchangeably referred to as “ethylene/MOCOS/terpolymer”), wherein the units of ethylene constitute a majority amount (wt %) of the monomers present in the polymer. In other words, the ethylene-based polymer composition includes ethylene monomer, MOCOS comonomer (and optional termonomer) each of the two monomers (or each of the three monomers when the termonomer is present) polymerized into the polymer backbone. In this way, the present ethylene-based polymer is structurally distinct compared to a polyethylene with a functional coagent grafted pendant to the polymer chain.

[0074] In addition to ethylene, the ethylene-based polymer composition includes units derived from a comonomer. The comonomer is a monocyclic organosiloxane of formula (I) [R.sup.1,R.sup.2SiO.sub.2/2].sub.n (interchangeably referred to as “MOCOS” or “MOCOS comonomer”), formula (I) being a molecule containing a single ring substructure composed of silicon and oxygen atoms disposed in an alternating arrangement; and formula (I) containing unsaturated organo (hydrocarbonyl) groups; and optionally hydrogen (“H”), saturated substituent groups or aromatic substituent groups. At least two unsaturated organo groups and each of at least two silicon atoms in the ring substructure have at least one unsaturated organo group bonded thereto and wherein after accounting for the unsaturated organo groups and oxygen atoms, any remaining valences of the silicon atoms are bonded to the hydrogen atom, saturated substituent groups, or aromatic substituent groups; or collection of such molecules.

[0075] The MOCOS may be a monocyclic organosiloxane composed of a 6-member ring (n=3), an 8-member ring (n=4), a 10-member ring (n−5), or a 12-member ring (n=6). The ring substructure is composed of units of formula (I):

[R.sup.1,R.sup.2SiO.sub.2/2].sub.n,

[0076] wherein n is an integer greater than or equal to 3, or n is 3, or 4 to 5, or 6,

[0077] each R.sup.1 is independently a (C.sub.2-C.sub.4)alkenyl or a H.sub.2C═C(R.sup.1a)—C(═O)—O—(CH.sub.2).sub.m—, wherein R.sup.1a is H or methyl,

[0078] each R.sup.2 is independently H, (C.sub.1-C.sub.4)alkyl, phenyl, or R.sup.1 (as defined above). In each [R.sup.1,R.sup.2SiO.sub.2/2] unit, the R.sup.1 group and the R.sup.2 group is bonded to its respective silicon atom. The units may be designated using conventional organosiloxane shorthand notations simply as D.sup.R1,R2 such that formula (I) becomes [D.sup.R1,R2].sub.n. R.sup.1 and R.sup.2 can be the same or different.

[0079] Nonlimiting examples of suitable compounds for MOCOS of formula (I) include: R.sup.1 is vinyl and R.sup.2 is ethyl for MOCOS shorthand designation D.sup.Vi,Et wherein Vi is vinyl and Et is ethyl; R.sup.1 is allyl and R.sup.2 is ethyl for MOCOS shorthand designation D.sup.Allyl,Et; R.sup.1 is butenyl (H.sub.2C═C(H)CH.sub.2CH.sub.2—) and R.sup.2 is ethyl for MOCOS shorthand designation D.sup.Butenyl,Et; R.sup.1 is vinyl and R.sup.2 is vinyl for MOCOS shorthand designation D.sup.Vi,Vi; R.sup.1 is allyl and R.sup.2 is allyl for MOCOS shorthand designation D.sup.Allyl,Allyl; R.sup.1 is butenyl (H.sub.2C═C(H)CH.sub.2CH.sub.2—) and R.sup.2 is butenyl for MOCOS shorthand designation D.sup.Butenyl,Butenyl; R.sup.1 is vinyl and R.sup.2 is phenyl for MOCOS shorthand designation D.sup.Vi,Ph wherein Ph is phenyl; R.sup.1 is allyl and R.sup.2 is phenyl for MOCOS shorthand designation D.sup.Allyl,Ph; R.sup.1 is butenyl (H.sub.2C═C(H)CH.sub.2CH.sub.2—) and R.sup.2 is phenyl for MOCOS shorthand designation D.sup.Butenyl,Ph.

[0080] When R.sup.2 is methyl (CH.sub.3), the unit may be designated more simply as D.sup.R1 such that formula (I) becomes [D.sup.R1].sub.n. Further nonlimiting examples of suitable compounds for MOCOS of formula (I) include: R.sup.1 is vinyl and R.sup.2 is methyl for MOCOS shorthand designation D.sup.Vi; R.sup.1 is allyl and R.sup.2 is methyl for MOCOS shorthand designation D.sup.Allyl; R.sup.1 is butenyl (H.sub.2C═C(H)CH.sub.2CH.sub.2—) and R.sup.2 is methyl for MOCOS shorthand designation D.sup.Butenyl.

[0081] In an embodiment, MOCOS of formula (I) each R.sup.1 is independently H.sub.2C═C(R.sup.1a). C(═O)—O—(CH.sub.2).sub.m— wherein R.sup.1a is H or methyl, and subscript m is an integer from 1, or 2 to 3 or to 4, and any range or individual value therein. In a further embodiment, each R.sup.2 is independently (C.sub.1-C.sub.2)alkyl or (C.sub.2-C.sub.3)alkenyl; or each R.sup.2 is independently (C.sub.1-C.sub.2)alkyl; or each R.sup.2 is independently methyl.

[0082] In an embodiment, MOCOS of formula (I) is 2,4,6-trimethyl-2,4,6-trivinyl-cyclotrisiloxane, “(D.sup.Vi).sub.3” (CAS No. 3901-77-7) having Structure (B) below:

##STR00002##

[0083] In an embodiment, MOCOS of formula (I) is 2,4,6,8-tetramethyl-2,4,6,8-tetravinyl-cyclotetrasiloxane, “(D.sup.Vi).sub.4” (CAS No. 2554-06-5), having Structure (C) below:

##STR00003##

[0084] In an embodiment, MOCOS of formula (I) is 2,4,6,8,10-pentamethyl-2,4,6,8,10-pentavinyl-cyclopentasiloxane, (D.sup.Vi).sub.5.

[0085] The MOCOS comonomer of formula (I) is present in the ethylene-based polymer in an amount from 0.01 wt % to 2 wt %, or from 0.01 wt % to 0.5 wt %, or from 0.05 wt % to 0.45 wt %, or from 0.1 wt % to 0.40 wt %, or from 0.15 wt % to 0.30 wt %, or from 0.05 wt % to 0.15 wt %. Weight percent is based on total weight of the ethylene-based polymer composition.

[0086] In addition to the ethylene and the MOCOS comonomer, the ethylene-based polymer composition includes optional units derived from a termonomer. When present, the termonomer is an olefin, an unsaturated ester, a functionalized alkene, silane, and combinations thereof. Nonlimiting examples of suitable termonomer (when the termonomer is present) include propylene, C.sub.4-C.sub.8 alpha-olefin, acrylate, (meth)acrylate, vinyl acetate, vinyltrimethoxysilane, and combinations thereof. When the termonomer is present in the ethylene-based polymer, the termonomer is present in an amount from 0.5 wt % to 20 wt %, or from 1 wt % to 15 wt %, of from 3 wt % to 12 wt %, or from 5 wt % to 10 wt %. Weight percent is based on the total weight of the ethylene-based polymer composition.

[0087] In an embodiment, the present ethylene-based polymer composition includes the ethylene/MOCOS copolymer of formula (I) and also includes a termonomer of formula (II)

[R.sup.1,R.sup.2SiO.sub.2/2].sub.n  formula (II)

[0088] wherein n is an integer greater than or equal to 3,

[0089] each R.sup.1 is independently a methyl group, a (C.sub.2-C.sub.4)alkenyl or a H.sub.2C═C(R.sup.1a)—C(═O)—O—(CH.sub.2).sub.m— with the proviso at least two R.sup.1's are not a methyl group,

[0090] wherein R.sup.1a is H or methyl,

[0091] m is an integer from 1 to 4, and

[0092] each R.sup.2 is independently H, (C.sub.1-C.sub.4)alkyl, phenyl, or R.sup.1.

[0093] The ethylene-based polymer composition may include one or more optional additives. When the additive is present, non-limiting examples of suitable additives include stabilizers, light stabilizers, UV absorbers, antioxidants, plasticizers, antistatic agents, pigments, dyes, nucleating agents, fillers, slip agents, fire retardants, processing aids, smoke inhibitors, peroxides, crosslinking coagents and scorch retardants, viscosity control agents and anti-blocking agents. The ethylene-based polymer composition may, for example, include less than 10 percent of the combined weight of one or more additives, based on the weight of the ethylene-based polymer composition.

[0094] In an embodiment, the ethylene-based polymer composition is treated with one or more stabilizers, for example, antioxidants, such as IRGANOX 1010, IRGANOX 1076 and IRGAFOS 168. In general, the ethylene-based polymer composition is treated with one or more stabilizers before extrusion or other melt processes.

[0095] In an embodiment, the ethylene-based polymer composition is an ethylene/MOCOS copolymer consisting of (i) ethylene and (ii) from 0.05 wt % to 0.5 wt % MOCOS copolymer selected from (D.sup.Vi).sub.3, (D.sup.Vi).sub.4, and (D.sup.Vi).sub.5, the ethylene/MOCOS copolymer having a Mw/Mn from 7.5 to 9.5, a vinyls content from 0.3600/1000 carbon atoms to 0.6200/1000 carbon atoms, a trans content from 0.1000/1000 carbon atoms to 0.3100/1000 carbon atoms, a MI from 2.0 g/10 min to 5.0 g/10 min, and a melt strength from 5.0 cN to 8.5 cN.

[0096] In an embodiment, the ethylene-based polymer composition is an ethylene/MOCOS copolymer consisting of (i) ethylene and (ii) from 0.05 wt % to 0.5 wt % (D.sup.Vi).sub.4, the ethylene/MOCOS copolymer composition having one, some, or all of the following properties:

[0097] (i) a Mw/Mn from 7.5 to 9.5; and/or

[0098] (ii) a vinyls content from 0.3600/1000 carbon atoms to 0.6200/1000 carbon atoms; and/or

[0099] (iii) a trans content from 0.1000/1000 carbon atoms to 0.3100/1000 carbon atoms; and/or

[0100] (iv) a MI from 2.0 g/10 min to 5.0 g/10 min, or from 2.5 g/10 min to 4.7 g/10 min; and/or

[0101] (v) a melt elasticity from 2.5 cN to 5.0 cN, or from 2.7 cN to 4.8 cN; and/or

[0102] (vi) a melt force from 20 mN to 40 mN, or from 22 mN to 37 mN; and/or

[0103] (vii) a melt strength from 5.0 cN to 8.5 cN, or from 5.5 cN to 8.5 cN.

[0104] In an embodiment, the ethylene-based polymer composition is an ethylene/MOCOS copolymer consisting of (i) ethylene and (ii) from 0.1 wt % to 0.5 wt % MOCOS copolymer selected from (D.sup.Vi).sub.4, the ethylene/MOCOS copolymer having a Mw/Mn from 7.0 to 7.5, a vinyls content from 0.5800/1000 carbons to 0.6200/1000 carbons, a trans content from 0.2000/1000 carbon atoms to 0.2500/1000 carbon atoms, and a MI from 35.0 g/10 min to 42.0 g/10 min.

[0105] In an embodiment, the ethylene-based polymer composition is an ethylene/MOCOS/MA terpolymer consisting of (i) ethylene, (ii) from 0.1 wt % to 0.5 wt % MOCOS and (iii) from 8 wt % to 12 wt % MA.

[0106] Applications

[0107] The ethylene-based polymer composition of the present disclosure may be employed in a variety of conventional thermoplastic fabrication processes to produce useful articles, including but not limited to monolayer and multilayer films; agricultural 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, foams. The present ethylene-based polymer composition is well-suited for applications requiring crosslinking by free radical methods, such as organic peroxides, such applications including, but not limited to, insulation for power cables.

[0108] The present ethylene-based polymer composition may be used in a variety of films, including but not limited to, clarity shrink films, agricultural films, collation shrink films, cast stretch films, silage films, stretch hood, sealants, and diaper backsheets. Other suitable applications include, but are not limited to, wire insulation, cable insulation, gaskets and profiles, adhesives; footwear components, and auto interior parts. The present ethylene-based polymer composition can be used as a part of the blend with LLDPE for agricultural films—big blown films.

[0109] By way of example, and not limitation, some embodiments of the present disclosure will now be described in detail in the following examples.

EXAMPLES

[0110] Materials used in the examples are set forth in Table 1 below.

TABLE-US-00001 TABLE 1 Material Description Source LDPE control Ethylene homopolymer LDPE1 control 4MI Dow Inc. Ethylene homopolymer LDPE1A control 2MI Ethylene/methyl acrylate copolymer control 6, 20 MI Ethylene homopolymer LDPE 12 control 40 MI comonomer 2,4,6,8-tetramethyl-2,4,6,8-tetravinyl- Alfa Aesar MOCOS cyclotetrasiloxane, (CAS No. 2554-06-5) (D.sup.Vi).sub.4 [00004] Termonomer Methyl acrylate (MA) Parchem Fine and Specialty Chemicals Organic peroxide Luperox 26 Arkema t-butyl peroxy-2-ethylhexanoate Propylene chain transfer agent Praxair

[0111] The amount of each material used in the inventive examples and in the comparative samples (controls) are provided in Table 2 below. A 545 milliliter (ml) stirred autoclave is charged with a mixture of ethylene, MOCOS ((D.sup.Vi).sub.4), propylene (as a chain transfer agent) and methyl acrylate (as a termonomer in comparative sample 6 and in inventive examples 7-8). Organic peroxide (Luperox 26) as a 0.5 wt %, 1 wt %, or 2 wt % solution in odorless mineral spirit was added as a polymerization initiator to the mixture, which was subjected to a set pressure of approximately 28,000 psi (1,969 kg/cm.sup.2). Reactor temperature was set to a target temperature of 220° C. Under the polymerization conditions shown in Table 2, ethylene/MOCOS copolymers were continuously synthesized and subsequently converted into pellet forms by melt extrusion. The conditions listed in Table 2 are averages over the time span that the samples were collected. The “autoclave-made” experimental reactor copolymers thus formed were found to have the characteristics set forth in Table 3.

TABLE-US-00002 TABLE 2 Polymerization Conditions Initiator Reactor Ethylene (D.sup.Vi).sub.4 MA Propylene Initiator solution Reactor Pressure Reactor feed rate feed rate feed rate feed rate solution feed rate conversion Example (psi) Temperature(° C.) (lb/hr) (lb/hr) (lb/hr) (lb/hr) wt % (cc/hr) (%) 1 control 28000 220.4 25.0 0 0 0.93 1.0 22.5 8.69 1A control 28003 220.5 24.9 0 0 0.81 1.0 18.8 9.55 IE2 27987 220.1 25.0 0.12 0 0.98 0.50 45.6 9.93 IE3 28024 220.6 24.9 0.24 0 1.1 1.0 41.1 10.5 IE4 28013 220.9 25.0 0.40 0 1.2 2.0 27.9 8.72 6 control 28007 220.4 25.0 0 0.55 0.68 2.0 10.7 11.9 IE7 28023 220.0 25.0 0.26 0.55 0.79 2.0 15.9 9.58 IE8 28038 220.7 25.0 0.44 0.53 0.93 2.0 25.5 10.4 IE10 27986 220.0 24.9 0.40 0 1.6 1.0 61.7 9.38 IE11 28048 219.6 24.9 0.12 0 0.95 1.0 22.6 10.1 12 control 27975 221.1 25.0 0 0 1.4 0.50 19.7 10.1 IE13 28027 219.7 25.1 0.24 0 1.5 1.0 53.0 14.9 Control = comparative sample IE = inventive example

[0112] The properties of resultant ethylene/MOCOS copolymers and ethylene/MOCOS/MA terpolymers are provided in Table 3 below.

TABLE-US-00003 TABLE 3 Properties for Ethylene/MOCOS Copolymer and Ethylene/MOCOS/MA Terpolymer MI MI (D.sup.Vi).sub.4 * MA * target measured ME MF MS Vinyls.sup.+ Trans.sup.+ 1 control 0.0 0.0 4.0 4.15 1.647 12.79 3.32 0.3500 0.0522 1A control 0.0 0.0 2.0 1.92 NM NM NM 0.3112 0.0489 IE2 0.15 0.0 4.0 3.51 3.173 25.03 7.65 0.3837 0.1283 IE3 0.3 0.0 4.0 3.47 3.727 29.48 6.33 0.4463 0.2043 IE4 0.50 0.0 4.0 2.85 4.649 36.88 8.37 0.5121 0.2984 6 control 0.0 10.0 2.0 NM NM NM NM NM NM IE7 0.30 10.0 20 NM NM NM NM NM NM IE8 0.50 10.0 20 NM NM NM NM NM NM IE10 0.50 0.0 40 14.66 NM NM NM 0.6167 0.3008 IE11 0.08 0.0 4.0 3.46 2.804 22.07 5.54 0.3786 0.1014 12 control 0.0 0.0 40.0 40.46 NM NM NM 0.5447 0.0755 IE13 0.30 0.0 40.0 37.25 NM NM NM 0.6092 0.2307 Control = comparative sample IE = inventive example MA = methyl acrylate, ME = melt elasticity (cN), MF = melt force (mN), MI = melt index (g/10 minutes), MS = melt strength (cN) NM = not measured * wt % (D.sup.Vi).sub.4 and wt % MA based on total weight ethylene-based polymer composition .sup.+Vinyls and trans are in mole %

TABLE-US-00004 TABLE 4 GPC Properties of ethylene/MOCOS copolymer Conventional GPC Absolute GPC Mw (Abs) ID* Mn Mw Mz Mp Mw/Mn Mn Mw Mz(BB) Mz(abs) Mz + 1(BB) Mz/Mw Mw (GPC) 1 control 11,471 82,089 410,969 41,675 7.16 11,976 182,857 886,632 6,210,161 1,986,555 33.96 2.23 (0/4) 1A control 12,213 93,388 433,074 44,680 7.65 13,354 202,853 862,196 4,839,926 1,867,682 23.86 2.17 (0/2) IE2 11,157 92,663 578,964 38,805 8.31 11,742 217,508 1,076,795 5,248,199 2,253,696 24.13 2.35 (0.15/4) IE3 10,975 102,163 782,298 35,617 9.31 10,526 294,562 1,357,367 7,140,095 2,527,086 24.24 2.88 (0.30/4) IE4 9,731 84,220 635,113 30,984 8.65 9,018 230,250 1,176,708 6,549,265 2,396,283 28.44 2.73 (0.50/4) IE10 9,566 89,026 795,450 27,402 9.31 9,040 303,637 1,357,442 8,346,058 2,315,738 27.49 3.41 (0.50/40) IE11 11,984 90,702 528,185 39,741 7.63 12,089 213,760 1,033,855 5,597,665 2,163,215 26.19 2.36 (0.08/4) 12 control 9,824 50,535 235,963 32,082 5.14 9,163 89,364 581,899 3,775,070 1,439,047 42.24 1.77 (0/40) IE13 8,997 64,132 522,051 25,620 7.13 8,253 182,120 1,099,960 7,415,758 2,092,632 40.72 2.84 (0.30/40) *ID = Identification, wt % (D.sup.Vi).sub.4 is first value and MI is second value in the closed parentheses

[0113] Proton NMR was used to characterize degree of incorporation/conversion of the (D.sup.Vi).sub.4 in selected samples. The Proton NMR detects the presence of Si—CH.sub.3 and Si-vinyl. On average, 2.5 double bonds per molecule of (D.sup.Vi).sub.4 are incorporated into the polyethylene backbone (Table 5). Bounded by no particular theory, it is believed that the copolymerization of the (D.sup.Vi).sub.4 with the ethylene and the incorporation of two double bonds produces H-branched structures resulting in an unexpected increase in melt strength.

TABLE-US-00005 TABLE 5 NMR data for ethylene/MOCOS copolymer NMR NMR SI-CH.sub.3 Si-vinyl Conversion per per (amount of 1000 1000 double bonds Sample carbons carbons consumed, %)  2 0.41 0.15 63.4  3 0.76 0.26 65.7  4 1.28 0.44 65.6 10 1.21 0.43 64.4 11 0.23 0.08 65.2 13 0.72 0.27 62.5

[0114] FIG. 1 shows melt force v. weight percent (D.sup.Vi).sub.4 (from left to right) for control 1, IE11, IE2, IE3, and IE4 from Table 3. As shown in FIG. 1, even low levels (0.5 wt % IE4 down to 0.08 wt % IE11) of the (D.sup.Vi).sub.4 result in a dramatic increase in melt force compared to the melt force for the comparative sample LDPE, control 1. The linear regression line through the inventive examples in FIG. 1 indicates a very good linear fit among the inventive examples (correlation coefficient R.sup.2 of 0.9989), while the y-intercept of the linear regression line (19.4 mN), which is much higher than the comparative example (12.8 mN), suggests highly non-linear behavior at very low levels of (D.sup.Vi).sub.4. That is, even very low levels of (D.sup.Vi).sub.4 lead to a surprisingly rapid rise in melt force; see for example IE11 0.08 wt % (D.sup.Vi).sub.4 with corresponding MF 22.07 mN and IE2 0.15 wt % (D.sup.Vi).sub.4 with corresponding MF 25.03 mN. The degree of effectiveness of (D.sup.Vi).sub.4 in increasing melt force at these low levels is an unexpected result.

[0115] It is specifically intended that the present disclosure not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.