Polymer composition and method of making the same

Abstract

A polymer composition comprises a polyolefin, a polar polymer, and a reactive polymeric processing aid. The reactive polymeric processing aid comprises an epoxy-functional copolymer grafted to a propylene polymer. A method of making a polymer composition comprises the steps of (a) combining at least one polyolefin, at least one polar polymer, and at least one reactive polymeric processing aid to produce a mixture, and (b) melt mixing the mixture at a temperature greater than the melting points of the polyolefin and polar polymer to produce a polymer composition.

Description

POLYMER COMPOSITION AND METHOD OF MAKING THE SAMETECHNICAL FIELD

[0001] The subject matter of this patent application relates to processing aids that improve the melt processing of mixed polymer streams, polymer compositions made with such processing aids, and methods of making such polymer compositions.BACKGROUND

[0002] Plastics have become ubiquitous in the modern world. Their durability and versatility and the relative ease with which they can be processed into myriad different forms have contributed to this rise to prominence. For example, plastics are today used to produce a variety of durable goods (e.g., home appliances, consumer electronics, furniture, and automobiles), consumable goods, and packaging materials for such goods.

[0003] Driven in part by an increased emphasis on sustainability, companies are striving to utilize increased amounts of recycled polymers or plastics in their products and / or the packaging for such products. However, utilizing recycled polymers and / or plastics in manufacturing processes often presents challenges that are not typically encountered when utilizing virgin polymers or plastics.

[0004] For example, most recycled polymer streams contain a mixture of different polymers, such as polyolefins and polar polymers, like polyethylene terephthalate (PET). The extrusion of such commingled polymer mixtures can be difficult because the molten polymers do not form a homogeneous melt. The heterogeneity of the polymer melt is due, at least in part, to differences in the chemical make-up and physical properties (e.g., surface energy and viscosity) of the different polymers. A high degree of heterogeneity in the recycled polymer melt generally manifests itself in a variety of undesirable ways during melt processing and extrusion, such as surging of the extruder and variability in the diameter of the polymer strand exiting the die (e.g., die swell variation). All these combine to make it difficult to melt process such recycled polymer streams into the consistent pellets needed to facilitate further use of the recycled polymer stream in the manufacture of products and / or packaging.

[0005] A need therefore remains for processing aids that improve the processability of recycled polymer streams containing a mixture of different polymers. A need also remains for polymer compositions made from recycled polymer streams using the processing aids, as well as methods for making such polymer compositions. Preferably, the polymer compositions made using such processing aids will exhibit enhanced processability relativeto the unmodified polymer stream, with less surging and / or die swell variation during extrusion and improved pelletization. The subject matter described in this application seeks to address these needs.BRIEF SUMMARY OF THE INVENTION

[0006] In a first embodiment, the invention provides a polymer composition comprising a polyolefin, a polar polymer, and a reactive polymeric processing aid. In a particular embodiment of such polymer composition, the polymer composition comprises:(a) a polyolefin selected from the group consisting of polypropylene homopolymers, polypropylene copolymers, polyethylene homopolymers, polyethylene copolymers, and mixtures thereof;(b) a polar polymer selected from the group consisting of polyester polymers, polyamide polymers, and mixtures thereof; and(c) about 0.1 to 5 wt.% of a reactive polymeric processing aid based on the total weight of the polymer composition, the reactive polymeric processing aid comprising an epoxy-functional copolymer grafted to a propylene polymer, wherein (i) the propylene polymer is selected from the group consisting of polypropylene homopolymers and propylene-ethylene random copolymers, (ii) wherein the epoxy-functional copolymer is a copolymer of at least one vinyl monomer and at least one epoxy-functional acrylate monomer, and (iii) the epoxy-functional copolymer comprises about 60 wt.% to about 90 wt.% of the mass of the reactive polymeric processing aid.

[0007] In a second embodiment, the invention provides a method of making a polymer composition, such as that described in the first embodiment. The method comprises the steps of combining a polyolefin, a polar polymer, and a reactive polymeric processing aid to produce a mixture and then melt mixing the mixture to produce a polymer composition. In a particular embodiment, the method comprises the steps of:(a) combining a polyolefin, a polar polymer, and a reactive polymeric processing aid to produce a mixture, wherein:(i) the polyolefin is selected from the group consisting of polypropylene homopolymers, polypropylene copolymers, polyethylene homopolymers, polyethylene copolymers, and mixtures thereof;(ii) the polar polymer is selected from the group consisting of polyester polymers, polyamide polymers, and mixtures thereof;(iii) the reactive polymeric processing aid comprises an epoxy-functional copolymer grafted to a propylene polymer, where the propylene polymer is selectedfrom the group consisting of polypropylene homopolymers and propylene-ethylene random copolymers, the epoxy-functional copolymer is a copolymer of at least one vinyl monomer and at least one epoxy-functional acrylate monomer, and the epoxyfunctional copolymer comprises about 60 wt.% to about 90 wt.% of the mass of the reactive polymeric processing aid; and(iv) the reactive polymeric processing aid comprises about 0.1 to 5 wt.% of the total weight of the mixture; and(b) melt mixing the mixture at a temperature greater than the melting points of the polyolefin and polar polymer to produce a polymer composition.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Fig. 1 is a photograph of an extruded strand made from Sample 1 A, which includes a United States penny for scale.

[0009] Fig. 2 is a photograph of an extruded strand made from Sample 1 B, which includes a United States penny for scale.

[0010] Fig. 3 is a photograph of an extruded strand made from Sample 1 C, which includes a United States penny for scale.

[0011] Fig. 4 is a photograph of an extruded strand made from Sample 1 D, which includes a United States penny for scale.

[0012] Fig. 5 is a photograph of an extruded strand made from Sample 1 E, which includes a United States penny for scale.

[0013] Fig. 6 is a photograph of an extruded strand made from Sample 1 F, which includes a United States penny for scale.

[0014] Fig. 7 is a polarized optical microscopy photograph of a cross section of a pellet made from Sample 2A.

[0015] Fig. 8 is a polarized optical microscopy photograph of a cross section of a pellet made from Sample 2B.

[0016] Fig. 9 is a polarized optical microscopy photograph of a cross section of a pellet made from Sample 2D.DETAILED DESCRIPTION OF THE INVENTION

[0017] In a first embodiment, the invention provides a polymer composition comprising a polyolefin, a polar polymer, and a reactive polymeric processing aid.

[0018] The polymer composition comprises a polyolefin or, in some embodiments, a mixture of two or more polyolefins. In a preferred embodiment, the polymer compositioncomprises a polyolefin selected from the group consisting of polypropylene homopolymers and copolymers, polyethylene homopolymers and copolymers, polybutylene homopolymers and copolymers, poly(4-methyl-1 -pentene) homopolymers and copolymers, poly(vinyl cyclohexane) homopolymers and copolymers, and mixtures thereof. Suitable polypropylene polymers include polypropylene homopolymers (e.g., atactic polypropylene homopolymer, isotactic polypropylene homopolymer, and syndiotactic polypropylene homopolymer), polypropylene copolymers (e.g., polypropylene random copolymers), polypropylene impact copolymers, and mixtures thereof. Suitable polypropylene copolymers include, but are not limited to, random copolymers made from the polymerization of propylene in the presence of one or more a-olefin comonomers, such as ethylene, but-1-ene (i.e., 1 -butene), and / or hex- 1 -ene (i.e., 1 -hexene), with polypropylene random copolymers made from propylene and ethylene being preferred. In such polypropylene random copolymers, the comonomer can be present in any suitable amount, but typically is present in an amount of less than about 10 wt.% (e.g., about 0.5 wt.% to about 10 wt.%, about 0.5 wt.% to about 7 wt.%, about 0.5 wt.% to about 5 wt.%, about 1 wt.% to about 10 wt.%, about 1 wt.% to about 7 wt.%, or about 1 wt.% to about 5 wt.%). Suitable polypropylene impact copolymers include, but are not limited to, those produced by the addition of a copolymer selected from the group consisting of ethylene-propylene rubber (EPR), ethylenepropylene-diene monomer (EPDM), polyethylene, and plastomers to a polypropylene homopolymer or polypropylene random copolymer. In such polypropylene impact copolymers, the copolymer can be present in any suitable amount, but typically is present in an amount of from about 5 wt.% to about 25 wt.%.

[0019] Suitable polyethylene polymers include low-density polyethylene, linear low- density polyethylene, medium-density polyethylene, high-density polyethylene, and combinations thereof. In certain preferred embodiments, the polyolefin is a polyethylene polymer selected from the group consisting of low-density polyethylene, linear low-density polyethylene, high-density polyethylene, and mixtures thereof. In another preferred embodiment, the polyolefin is a high-density polyethylene. The high-density polyethylene polymers suitable for use in the polymer composition generally have a density of greater than about 0.940 g / cm3. There is no upper limit to the suitable density of the polymer, but high-density polyethylene polymers typically have a density that is less than about 0.980 g / cm3(e.g., less than about 0.975 g / cm3). The polyethylene polymers (e.g., high-density polyethylene polymers) suitable for use in the polymer composition can be either homopolymers or copolymers of ethylene with one or more a-olefins. Suitable a-olefins include, but are not limited to, 1 -butene, 1 -hexene, 1 -octene, 1 -decene, and 4-methyl-1 - pentene. The comonomer can be present in the polyethylene copolymer in any suitableamount, such as an amount of about 5 wt.% or less (e.g., about 3 mol.% or less). As will be understood by those of ordinary skill in the art, the amount of comonomer suitable for the polyethylene copolymer is largely driven by the end use for the copolymer and the required or desired polymer properties dictated by that end use.

[0020] As noted above, the polymer composition can comprise a mixture of two or more polyolefins. In such an embodiment, the two polyolefins need not be made from entirely different monomers or mixtures of monomers. Thus, for example, the polymer composition can comprise a mixture of a polypropylene homopolymer with one or more polypropylene random copolymers. Likewise, the polymer composition can comprise a mixture of two or more different polyethylene polymers, such as a mixture of one or more high-density polyethylene polymers with one or more linear low-density polyethylene polymers. In a preferred embodiment, the polymer composition comprises (a) a first polyolefin selected from polypropylene homopolymers, polypropylene copolymers, and mixtures thereof and (b) a second polyolefin selected from polyethylene homopolymers, polyethylene copolymers, and mixtures thereof. In such an embodiment, the first polyolefin can be any of the polypropylene homopolymers or polypropylene copolymers described above, including a mixture of such homopolymers and / or copolymers. Further, the second polyolefin in such an embodiment can be any of the polyethylene homopolymers or polyethylene copolymers described above, including a mixture of such homopolymers and / or copolymers.

[0021] The polyolefin polymer(s) preferably comprise about 5 wt.% or more, about 10 wt.% or more, about 15 wt.% or more, about 20 wt.% or more, about 25 wt.% or more, about 30 wt.% or more, about 35 wt.% or more, or about 40 wt.% or more of the total mass of polyolefin(s) and polar polymer(s) present in the polymer composition. In other embodiments, the polyolefin polymer(s) preferably comprise about 95 wt.% or less, about 90 wt.% or less, about 85 wt.% or less, about 80 wt.% or less, or about 75 wt.% or less of the total mass of polyolefin(s) and polar polymer(s) present in the polymer composition. Thus, in a series of preferred embodiments, the polyolefin polymer(s) comprise about 5 wt.% to about 95 wt.% (e.g., about 5 wt.% to about 90 wt.%, about 5 wt.% to about 85 wt.%, about 5 wt.% to about 80 wt.%, or about 5 wt.% to about 75 wt.%), about 10 wt.% to about 95 wt.% (e.g., about 10 wt.% to about 90 wt.%, about 10 wt.% to about 85 wt.%, about 10 wt.% to about 80 wt.%, or about 10 wt.% to about 75 wt.%), about 15 wt.% to about 95 wt.% (e.g., about 15 wt.% to about 90 wt.%, about 15 wt.% to about 85 wt.%, about 15 wt.% to about 80 wt.%, or about 15 wt.% to about 75 wt.%), about 20 wt.% to about 95 wt.% (e.g., about 20 wt.% to about 90 wt.%, about 20 wt.% to about 85 wt.%, about 20 wt.% to about 80 wt.%, or about20 wt.% to about 75 wt.%), about 25 wt.% to about 95 wt.% (e.g., about 25 wt.% to about 90 wt.%, about 25 wt.% to about 85 wt.%, about 25 wt.% to about 80 wt.%, or about 25 wt.% to about 75 wt.%), about 30 wt.% to about 95 wt.% (e.g., about 30 wt.% to about 90 wt.%, about 30 wt.% to about 85 wt.%, about 30 wt.% to about 80 wt.%, or about 30 wt.% to about 75 wt.%), about 35 wt.% to about 95 wt.% (e.g., about 35 wt.% to about 90 wt.%, about 35 wt.% to about 85 wt.%, about 35 wt.% to about 80 wt.%, or about 35 wt.% to about 75 wt.%), or about 40 wt.% to about 95 wt.% (e.g., about 40 wt.% to about 90 wt.%, about 40 wt.% to about 85 wt.%, about 40 wt.% to about 80 wt.%, or about 40 wt.% to about 75 wt.%) of the total mass of polyolefin(s) and polar polymer(s) present in the polymer composition.

[0022] The polymer composition comprises at least one polar polymer or, in some embodiments, a mixture of two or more polar polymers. In a preferred embodiment, the polymer composition comprises a polar polymer selected from the group consisting of polyester polymers, polyamide polymers, and mixtures thereof. Polyester polymers are made from the reaction of a dicarboxylic acid (e.g., terephthalic acid) and a diol (e.g., ethylene glycol). Suitable polyester polymers include, but are not limited to, polyethylene terephthalate) (PET), poly(butylene terephthalate) (PBT), poly(hexamethylene terephthalate) (PHT), polypropylene terephthalate (PTT), polylactic acid (PLA), and mixtures thereof. In a preferred embodiment, the polymer composition comprises a polyester polymer selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and mixtures thereof. In another preferred embodiment, the polymer composition comprises polyethylene terephthalate.

[0023] Polyamide polymers are generally described as polymers with repeating units linked by amide groups. Preferably, any polyamide polymer in the polymer composition is a thermoplastic polyamide polymer, such as an aliphatic polyamide polymer or a polyphthalamide polymer. Suitable aliphatic polyamide polymers include, but are not limited to, poly(hexamethylene adipamide) (also known as Nylon 66, polyamide 66, or PA66), polycaprolactam (also known as Nylon 6, polyamide 6, or PA6), and mixtures thereof. Suitable polyphthalamide polymers include, but are not limited to, copolymers of terephthalic acid and / or isophthalic acid with aliphatic diamines (e.g., aliphatic C6-C12 diamines), such as copolymers of terephthalic acid and hexamethylenediamine (polyamide 6T or PA 6T), copolymers of terephthalic acid, adipic acid, and hexamethylenediamine (polyamide 6T / 66 or PA 6T / 66), and copolymers of terephthalic acid, isophthalic acid, and hexamethylenediamine (polyamide 6T / 6I or PA6T / 6I). In a preferred embodiment, the polymer composition comprises an aliphatic polyamide polymer, such as poly(hexamethylene adipamide), polycaprolactam, and mixtures thereof.

[0024] As noted above, the polymer composition can comprise a combination of two or more of any of the polar polymers described above. In a preferred embodiment, the polymer composition comprises a mixture of at least one polyester polymer and at least one polyamide polymer. In one such embodiment, the polymer composition comprises a mixture of (i) a polyester polymer selected from the group consisting of polyethylene terephthalate), poly(butylene terephthalate), and mixtures thereof and (ii) a polyamide polymer selected from the group consisting of poly(hexamethylene adipamide), polycaprolactam, and mixtures thereof.

[0025] The polar polymer(s) preferably comprise about 5 wt.% or more, about 10 wt.% or more, about 15 wt.% or more, about 20 wt.% or more, or about 25 wt.% or more of the total mass of polyolefin(s) and polar polymer(s) present in the polymer composition. In other embodiments, the polar polymers preferably comprise about 95 wt.% or less, about 90 wt.% or less, about 85 wt.% or less, about 80 wt.% or less, about 75 wt.% or less, about 70 wt.% or less, about 65 wt.% or less, or about 60 wt.% or less of the total mass of polyolefin(s) and polar polymer(s) present in the polymer composition. Thus, in a series of preferred embodiments, the polar polymer(s) comprise about 5 wt.% to about 95 wt.% (e.g., about 5 wt.% to about 90 wt.%, about 5 wt.% to about 85 wt.%, about 5 wt.% to about 80 wt.%, about 5 wt.% to about 75 wt.%, about 5 wt.% to about 70 wt.%, about 5 wt.% to about 65 wt.%, or about 5 wt.% to about 60 wt.%), about 10 wt.% to about 95 wt.% (e.g., about 10 wt.% to about 90 wt.%, about 10 wt.% to about 85 wt.%, about 10 wt.% to about 80 wt.%, about 10 wt.% to about 75 wt.%, about 10 wt.% to about 70 wt.%, about 10 wt.% to about 65 wt.%, or about 10 wt.% to about 60 wt.%), about 15 wt.% to about 95 wt.% (e.g., about 15 wt.% to about 90 wt.%, about 15 wt.% to about 85 wt.%, about 15 wt.% to about 80 wt.%, about 15 wt.% to about 75 wt.%, about 15 wt.% to about 70 wt.%, about 15 wt.% to about 65 wt.%, or about 15 wt.% to about 60 wt.%), about 20 wt.% to about 95 wt.% (e.g., about 20 wt.% to about 90 wt.%, about 20 wt.% to about 85 wt.%, about 20 wt.% to about 80 wt.%, about 20 wt.% to about 75 wt.%, about 20 wt.% to about 70 wt.%, about 20 wt.% to about 65 wt.%, or about 20 wt.% to about 60 wt.%), or about 25 wt.% to about 95 wt.% (e.g., about 25 wt.% to about 90 wt.%, about 25 wt.% to about 85 wt.%, about 25 wt.% to about 80 wt.%, about 25 wt.% to about 75 wt.%, about 25 wt.% to about 70 wt.%, about 25 wt.% to about 65 wt.%, or about 25 wt.% to about 60 wt.%) of the total mass of polyolefin(s) and polar polymer(s) present in the polymer composition.

[0026] The polymer composition comprises at least one reactive polymeric processing aid. The reactive polymeric processing aid preferably comprises an epoxyfunctional copolymer grafted to a propylene polymer. As utilized herein, the term “epoxy-functional copolymer” refers to a copolymer comprising one or more pendant epoxide groups, with copolymers comprising multiple pendant epoxide groups being preferred. The reactive polymeric processing aid preferably has a “comb” structure in which the propylene polymer provides a “backbone” onto which multiple epoxy-functional copolymer side chains are grafted.

[0027] The propylene polymer of the reactive polymeric processing aid can be any suitable propylene polymer. In a preferred embodiment, the propylene polymer is selected from the group consisting of polypropylene homopolymers and polypropylene random copolymers. Suitable polypropylene random copolymers include, but are not limited to, random copolymers made from the polymerization of propylene in the presence of one or more a-olefin comonomers, such as ethylene, but-1 -ene (i.e., 1 -butene), and / or hex-1 -ene (i.e., 1 -hexene). In these polypropylene random copolymers, the comonomer preferably is present in an amount of about 4 wt.% or more. Further, the comonomer can be present in an amount of up to about 50 wt.%, about 40 wt.%, about 30 wt.%, or about 20 wt.%. Thus, when the propylene polymer of the reactive polymeric processing is a polypropylene random copolymer, the polypropylene random copolymer preferably comprises about 4 wt.% to about 50 wt.%, about 4 wt.% to about 40 wt.%, about 4 wt.% to about 30 wt.%, or about 4 wt.% to about 20 wt.% of the comonomer. When the propylene polymer of the reactive polymeric processing aid is a polypropylene random copolymer, the polypropylene random copolymer preferably is made from propylene and ethylene — it is a propylene-ethylene random copolymer.

[0028] As noted above, the reactive polymeric processing aid also comprises an epoxy-functional copolymer grafted to the propylene polymer. The epoxy-functional copolymer preferably is a copolymer made from at least one vinyl monomer and at least one epoxy-functional monomer, such as an epoxy-functional vinyl monomer (e.g., an epoxyfunctional acrylate monomer). The vinyl monomer used to make the epoxy-functional copolymer can be any suitable vinyl monomer, such as acrylic acid, acrylates (e.g., methyl acrylate, ethyl acrylate, butyl acrylate, etc.), methacrylic acid, methacrylates (e.g., methyl methacrylate, ethyl acrylate, butyl acrylate, etc.), styrene, substituted styrenes, and mixtures thereof. Suitable substituted styrenes can be substituted with one or more non-hydrogen substituents (e.g., halogens, alkyl groups, etc.) on the phenyl group, as in 4-methylstyrene, and / or on the vinyl group, as in alpha-methylstyrene. In a preferred embodiment, the vinyl monomer is selected from the group consisting of styrene, substituted styrenes, and mixtures thereof. More preferably, the vinyl monomer used in making the epoxy-functional copolymer is styrene. The epoxy-functional monomer used in making the epoxy-functionalcopolymer can be any suitable epoxy-functional monomer, such as the glycidol esters of acrylic acid and methacrylic acid. Thus, in a preferred embodiment, the epoxy-functional acrylate monomer is selected from the group consisting of glycidyl acrylate, glycidyl methacrylate, and mixtures thereof. More preferably, the epoxy-functional acrylate monomer is glycidyl methacrylate. Thus, in one particularly preferred embodiment, the epoxyfunctional copolymer is a copolymer of styrene and glycidyl methacrylate. In another preferred embodiment, the epoxy-functional copolymer is a copolymer of styrene, methyl methacrylate, and glycidyl methacrylate. The epoxy-functional copolymer grafted to the propylene polymer can be either a block copolymer or a random copolymer of any of the monomers described above. Preferably, the epoxy-functional copolymer is a random copolymer.

[0029] The epoxy-functional copolymer of the reactive polymeric processing aid can be made with any suitable ratio of the vinyl monomer(s) and the epoxy-functional monomer(s) (e.g., epoxy-functional acrylate monomer(s)). Preferably, the epoxy-functional copolymer comprises about 1 wt.% or more, about 5 wt.% or more, about 10 wt.% or more, or about 15 wt.% or more of the epoxy-functional monomer(s). In other embodiments, the epoxy-functional copolymer comprises about 50 wt.% or less, about 45 wt.% or less, about 40 wt.% or less, about 35 wt.% or less, or about 30 wt.% or less of the epoxy-functional monomer(s). Thus, in a series of preferred embodiments, the epoxy-functional copolymer preferably comprises about 1 wt.% to about 50 wt.% (e.g., about 1 wt.% to about 45 wt.%, about 1 wt.% to about 40 wt.%, about 1 wt.% to about 35 wt.%, or about 1 wt.% to about 30 wt.%), about 5 wt.% to about 50 wt.% (e.g., about 5 wt.% to about 45 wt.%, about 5 wt.% to about 40 wt.%, about 5 wt.% to about 35 wt.%, or about 5 wt.% to about 30 wt.%), about 10 wt.% to about 50 wt.% (e.g., about 10 wt.% to about 45 wt.%, about 10 wt.% to about 40 wt.%, about 10 wt.% to about 35 wt.%, or about 10 wt.% to about 30 wt.%), or about 15 wt.% to about 50 wt.% (e.g., about 15 wt.% to about 45 wt.%, about 15 wt.% to about 40 wt.%, about 15 wt.% to about 35 wt.%, or about 15 wt.% to about 30 wt.%) of the epoxy-functional monomer(s). In such embodiments, the remainder of the epoxy-functional copolymer preferably is the vinyl monomer(s). Thus, the epoxy-functional copolymer preferably comprises about 50 wt.% to about 99 wt.% (e.g., about 55 wt.% to about 99 wt.%, about 60 wt.% to about 99 wt.%, about 65 wt.% to about 99 wt.%, or about 70 wt.% to about 99 wt.%), about 50 wt.% to about 95 wt.% (e.g., about 55 wt.% to about 95 wt.%, about 60 wt.% to about 95 wt.%, about 65 wt.% to about 95 wt.%, or about 70 wt.% to about 95 wt.%), about 50 wt.% to about 90 wt.% (e.g., about 55 wt.% to about 90 wt.%, about 60 wt.% to about 90 wt.%, about 65 wt.% to about 90 wt.%, or about 70 wt.% to about 90 wt.%), or about 50 wt.%to about 85 wt.% (e.g., about 55 wt.% to about 85 wt.%, about 60 wt.% to about 85 wt.%, about 65 wt.% to about 85 wt.%, or about 70 wt.% to about 85 wt.%) of the vinyl monomer(s).

[0030] The reactive polymeric processing aid can comprise any suitable amount of the epoxy-functional copolymer (i.e., any suitable amount of the epoxy-functional copolymer can be grafted to the propylene polymer). Preferably, the epoxy-functional copolymer comprises about 50 wt.% or more, about 60 wt.% or more, about 70 wt.% or more, or about 75 wt.% or more of the mass of the reactive polymeric processing aid. In other preferred embodiments, the epoxy-functional copolymer preferably comprises about 95 wt.% or less, about 90 wt.% or less, or about 85 wt.% or less of the mass of the reactive polymeric processing aid. Thus, in a series of preferred embodiments, the epoxy-functional copolymer comprises about 50 wt.% to about 95 wt.% (e.g., about 50 wt.% to about 90 wt.% or about 50 wt.% to about 85 wt.%), about 60 wt.% to about 95 wt.% (e.g., about 60 wt.% to about 90 wt.% or about 60 wt.% to about 85 wt.%), about 70 wt.% to about 95 wt.% (e.g., about 70 wt.% to about 90 wt.% or about 70 wt.% to about 85 wt.%), or about 75 wt.% to about 95 wt.% (e.g., about 75 wt.% to about 90 wt.% or about 75 wt.% to about 85 wt.%) of the mass of the reactive polymeric processing aid.

[0031] The reactive polymeric processing aid described herein can be made by any suitable method. For example, the reactive polymeric processing aid can be made by controlled free radical polymerization of a vinyl monomer and an epoxy-functional acrylate monomer to produce the epoxy-functional copolymer followed by grafting of the epoxyfunctional copolymer to a propylene polymer using controlled free radical polymerization. Suitable methods for making the reactive polymeric processing aid are described, for example, in International Patent Application No. WO 2007 / 023375 A2 and International Patent Application No. WO 2018 / 007869 A1 .

[0032] The polymer composition can comprise any amount of reactive polymeric processing aid(s) that improves the melt processing of the mixture of polyolefin and polar polymer described above. As will be understood by those skilled in the art, the amount of reactive polymeric processing aid(s) may depend upon several factors, such as the particular polyolefin(s) and polar polymer(s) present in the polymer composition, the amount or ratio of polyolefin(s) and polar polymer(s) present in the polymer composition, and the structure and composition of the reactive polymeric processing aid(s). Thus, for example, a polymer composition comprising a polypropylene homopolymer and polyethylene terephthalate) may require a different amount of reactive polymeric processing aid(s) than a polymer composition comprising a polypropylene homopolymer and poly(hexamethyleneadipamide). Preferably, the polymer composition comprises about 0.1 wt.% or more, about 0.25 wt.% or more, about 0.5 wt.% or more, about 0.75 wt.% or more, or about 1 wt.% or more of the reactive polymeric processing aid based on the total weight of the polymer composition. In other embodiments, the polymer composition preferably comprises about 10 wt.% or less, about 7.5 wt.% or less, about 5 wt.% or less, about 4.5 wt.% or less, about 4 wt.% or less, about 3.5 wt.% or less, or about 3 wt.% or less of the reactive polymeric processing aid based on the total weight of the polymer composition. Thus, in a series of preferred embodiments, the polymer composition comprises about 0.1 wt.% to about 10 wt.% (e.g., about 0.1 wt.% to about 7.5 wt.%, about 0.1 wt.% to about 5 wt.%, about 0.1 wt.% to 4.5 wt.%, about 0.1 wt.% to about 4 wt.%, about 0.1 wt.% to about 3.5 wt.%, or about 0.1 wt.% to about 3 wt.%), about 0.25 wt.% to about 10 wt.% (e.g., about 0.25 wt.% to about 7.5 wt.%, about 0.25 wt.% to about 5 wt.%, about 0.25 wt.% to 4.5 wt.%, about 0.25 wt.% to about 4 wt.%, about 0.25 wt.% to about 3.5 wt.%, or about 0.25 wt.% to about 3 wt.%), about 0.5 wt.% to about 10 wt.% (e.g., about 0.5 wt.% to about 7.5 wt.%, about 0.5 wt.% to about 5 wt.%, about 0.5 wt.% to 4.5 wt.%, about 0.5 wt.% to about 4 wt.%, about 0.5 wt.% to about 3.5 wt.%, or about 0.5 wt.% to about 3 wt.%), about 0.75 wt.% to about 10 wt.% (e.g., about 0.75 wt.% to about 7.5 wt.%, about 0.75 wt.% to about 5 wt.%, about 0.75 wt.% to 4.5 wt.%, about 0.75 wt.% to about 4 wt.%, about 0.75 wt.% to about 3.5 wt.%, or about 0.75 wt.% to about 3 wt.%), or about 1 wt.% to about 10 wt.% (e.g., about 1 wt.% to about 7.5 wt.%, about 1 wt.% to about 5 wt.%, about 1 wt.% to 4.5 wt.%, about 1 wt.% to about 4 wt.%, about 1 wt.% to about 3.5 wt.%, or about 1 wt.% to about 3 wt.%) of the reactive polymeric processing aid based on the total weight of the polymer composition. If the polymer composition comprises two or more different reactive polymeric processing aids, each reactive polymeric processing aid can be present in an amount falling within at least one of the ranges recited above, or the total amount of reactive polymeric processing aids present in the polymer composition falls within at least one of the ranges recited above. Preferably, the total amount of reactive polymeric processing aid(s) present in the polymer composition falls within at least one of the ranges recited above.

[0033] As noted above, mixtures of polyolefins and polar polymers typically are difficult to melt process (e.g., extrude) because the different polymers do not form a heterogenous melt. The heterogeneity of such a melt negatively impacts the processability of the melt mixture. However, with the inclusion of one or more reactive polymeric processing aids as described herein, the polymer compositions described herein exhibit markedly improved processability. For example, when the polymer composition is melt processed using an extruder, the extruder experiences less surging and less variation in thetorque required to drive the extruder screw(s) as compared to when a similar polymer composition excluding the reactive polymeric processing aid is processed. Additionally, the extrudate exiting the die of the extruder exhibits a more uniform diameter (i.e., there is less die swell variation). These improvements permit the polymer composition of the invention to be more easily and / or more uniformly pelletized or otherwise subsequently processed as compared to a conventional mixture of such polymers (i.e., a mixture that does not include the reactive polymeric processing aid).

[0034] In a second embodiment, the invention provides a method of making a polymer composition, such as that described in the first embodiment. The method comprises the steps of combining at least one polyolefin, at least one polar polymer, and at least one reactive polymeric processing aid to produce a mixture and then melt mixing the mixture to produce a polymer composition. The polyolefin(s), polar polymer(s), and reactive polymeric processing aid(s) used in the method can be any of the polyolefins, polar polymers, and reactive polymeric processing aids described above in connection with the polymer composition embodiments. Further, the amounts of the polyolefin(s), polar polymer(s), and / or reactive polymeric processing aid(s) present in the mixture can be any of the amounts described above in connection with the polymer composition embodiments.

[0035] The mixture of polyolefin(s), polar polymer(s), and reactive polymeric processing aid(s) can be melt mixed or compound by any suitable means. Preferably, the mixture is melt mixed or compounded at a temperature that is greater than the melting points of the polyolefin(s) and polar polymer(s) present in the mixture. Those skilled in the art will understand that the melt mixing or compounding of the mixture can be conducted in stages or steps that are performed at different temperatures. Thus, when a reference is made to the temperature at which the mixture is melt mixed or compounded, it should be understood as a reference to the maximum temperature to which the mixture is heated or exposed during the melt mixing or compounding step of the method. In other preferred embodiments, the mixture is melt mixed or compounded at a maximum temperature of about 250 °C to about 270 °C (e.g., about 255 °C to about 265 °C, or about 260 °C). In another preferred embodiment, the mixture of polyolefin(s), polar polymer(s), and reactive polymeric processing aid(s) is melt mixed or compounded using an extruder, such as a single screw extruder or a twin screw extruder.

[0036] After the mixture has been melt mixed or compounded to produce a polymer composition, the resulting polymer composition can be further processed in any suitable way. For example, when the mixture is melt mixed in an extruder, the polymer compositionexiting the extruder’s die can be cooled (e.g., submerged in a water bath) to solidify it and then chopped into pellets for later use.

[0037] The inventions and the potential embodiments thereof described in and embraced by the foregoing description may be further understood by reference to the particular embodiments set forth below. As such, these embodiments are included for illustrative purposes only (e.g., describing potentially preferred embodiments of the invention) and are not intended to limit the foregoing description in any manner.Embodiment 1 . A polymer composition comprising:(a) at least one polyolefin;(b) at least one polar polymer; and(c) at least one reactive polymeric processing aid comprising an epoxy-functional copolymer grafted to a propylene polymer.Embodiment 2. The polymer composition of embodiment 1 , wherein the polyolefin is selected from the group consisting of polypropylene homopolymers, polypropylene copolymers, polyethylene homopolymers, polyethylene copolymers, and mixtures thereof.Embodiment 3. The polymer composition of embodiment 1 or embodiment 2, wherein the polymer composition comprises (a) a first polyolefin selected from the group consisting of polypropylene homopolymers, polypropylene copolymers, and mixtures thereof and (b) a second polyolefin selected from the group consisting of polyethylene homopolymers, polyethylene copolymers, and mixtures thereof.Embodiment 4. The polymer composition of embodiment 3, wherein the second polyolefin is selected from the group consisting of high-density polyethylene, low- density polyethylene, linear low-density polyethylene, and mixtures thereof.Embodiment 5. The polymer composition of any of embodiments 1 -4, wherein the polyolefin comprises about 5 wt.% to about 80 wt.% of the total mass of polyolefin and polar polymer present in the polymer composition.Embodiment 6. The polymer composition of embodiment 5, wherein the polyolefin comprises about 10 wt.% to about 75 wt.% of the total mass of polyolefin and polar polymer present in the polymer composition.Embodiment 7. The polymer composition of any of embodiments 1 -6, wherein the polar polymer is selected from the group consisting of polyester polymers, polyamide polymers, and mixtures thereof.Embodiment 8. The polymer composition of embodiment 7, wherein the polar polymer is a polyester polymer.Embodiment 9. The polymer composition of embodiment 8, wherein the polar polymer is selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and mixtures thereof.Embodiment 10. The polymer composition of embodiment 9, wherein the polar polymer is polyethylene terephthalate.Embodiment 11 . The polymer composition of any of embodiments 1 -10, wherein the polar polymer comprises about 5 wt.% to about 70 wt.% of the total mass of polyolefin and polar polymer present in the polymer composition.Embodiment 12. The polymer composition of embodiment 11 , wherein the polar polymer comprises about 10 wt.% to about 65 wt.% of the total mass of polyolefin and polar polymer present in the polymer composition.Embodiment 13. The polymer composition of any of embodiments 1 -12, wherein the propylene polymer is selected from the group consisting of polypropylene homopolymers and propylene-ethylene random copolymers.Embodiment 14. The polymer composition of embodiment 13, wherein the propylene polymer is a propylene-ethylene random copolymer comprising about 4 wt.% to about 50 wt.% ethylene.Embodiment 15. The polymer composition of embodiment 14, wherein the propylene-ethylene random copolymer comprises about 4 wt.% to about 20 wt.% ethylene.Embodiment 16. The polymer composition of any of embodiments 1 -15, wherein the epoxy-functional copolymer is a copolymer of at least one first vinyl monomer and at least one second, epoxy-functional vinyl monomer.Embodiment 17. The polymer composition of embodiment 16, wherein the epoxy-functional copolymer is a random copolymer of at least one vinyl monomer and at least one epoxy-functional acrylate monomer.Embodiment 18. The polymer composition of any of embodiments 1 -17, wherein the epoxy-functional copolymer comprises about 60 wt.% to about 90 wt.% of the mass of the reactive polymeric processing aid.Embodiment 19. The polymer composition of embodiment 18, wherein the epoxy-functional copolymer comprises about 70 wt.% to about 90 wt.% of the mass of the reactive polymeric processing aid.Embodiment 20. The polymer composition of any of embodiments 16-19, wherein the vinyl monomer is selected from the group consisting of styrene, substituted styrenes, and mixtures thereof.Embodiment 21 . The polymer composition of embodiment 20, wherein the vinyl monomer is styrene.Embodiment 22. The polymer composition of any of embodiments 17-21 , wherein the epoxy-functional acrylate monomer is selected from the group consisting of glycidyl acrylate, glycidyl methacrylate, and mixtures thereof.Embodiment 23. The polymer composition of embodiment 22, wherein the epoxy-functional acrylate monomer is glycidyl methacrylate.Embodiment 24. The polymer composition of any of embodiments 1 -23, wherein the polymer composition comprises about 0.1 wt.% to about 10 wt.% of the reactive polymeric processing aid(s), based on the total weight of the polymer composition.Embodiment 25. The polymer composition of embodiment 24, wherein the polymer composition comprises about 0.1 wt.% to about 5 wt.% of the reactive polymeric processing aid(s), based on the total weight of the polymer composition.Embodiment 26. The polymer composition of embodiment 25, wherein the polymer composition comprises about 0.25 wt.% to about 5 wt.% of the reactive polymeric processing aid(s), based on the total weight of the polymer composition.Embodiment 27. The polymer composition of embodiment 26, wherein the polymer composition comprises about 0.5 wt.% to about 5 wt.% of the reactive polymeric processing aid(s), based on the total weight of the polymer composition.Embodiment 28. The polymer composition of embodiment 27, wherein the polymer composition comprises about 0.75 wt.% to about 5 wt.% of the reactive polymeric processing aid(s), based on the total weight of the polymer composition.Embodiment 29. The polymer composition of embodiment 28, wherein the polymer composition comprises about 1 wt.% to about 5 wt.% of the reactive polymeric processing aid(s), based on the total weight of the polymer composition.Embodiment 30. The polymer composition of embodiment 25, wherein the polymer composition comprises about 0.1 wt.% to about 3 wt.% of the reactive polymeric processing aid(s), based on the total weight of the polymer composition.Embodiment 31 . The polymer composition of embodiment 30, wherein the polymer composition comprises about 0.25 wt.% to about 3 wt.% of the reactive polymeric processing aid(s), based on the total weight of the polymer composition.Embodiment 32. The polymer composition of embodiment 31 , wherein the polymer composition comprises about 0.5 wt.% to about 3 wt.% of the reactive polymeric processing aid(s), based on the total weight of the polymer composition.Embodiment 33. The polymer composition of embodiment 32, wherein the polymer composition comprises about 0.75 wt.% to about 3 wt.% of the reactive polymeric processing aid(s), based on the total weight of the polymer composition.Embodiment 34. The polymer composition of embodiment 33, wherein the polymer composition comprises about 1 wt.% to about 3 wt.% of the reactive polymeric processing aid(s), based on the total weight of the polymer composition.Embodiment 35. A method of making a polymer composition, the method comprising the steps of:(a) combining at least one polyolefin, at least one polar polymer, and at least one reactive polymeric processing aid to produce a mixture, wherein the reactive polymeric processing aid comprises an epoxy-functional copolymer grafted to a propylene polymer; and(b) melt mixing the mixture at a temperature greater than the melting points of the polyolefin and polar polymer to produce a polymer composition.Embodiment 36. The method of embodiment 35, wherein the polyolefin is selected from the group consisting of polypropylene homopolymers, polypropylene copolymers, polyethylene homopolymers, polyethylene copolymers, and mixtures thereof.Embodiment 37. The method of embodiment 35 or embodiment 36, wherein the mixture comprises (a) a first polyolefin selected from polypropylene homopolymers, polypropylene copolymers, and mixtures thereof and (b) a second polyolefin selected from polyethylene homopolymers, polyethylene copolymers, and mixtures thereof.Embodiment 38. The method of any of embodiments 35-37, wherein the polyolefin comprises about 5 wt.% to about 80 wt.% of the total mass of polyolefin and polar polymer present in the mixture.Embodiment 39. The method of embodiment 38, wherein the polyolefin comprises about 10 wt.% to about 75 wt.% of the total mass of polyolefin and polar polymer present in the mixture.Embodiment 40. The method of any of embodiments 35-39, wherein the polar polymer is selected from the group consisting of polyester polymers, polyamide polymers, and mixtures thereof.Embodiment 41 . The method of embodiment 40, wherein the polar polymer is a polyester polymer.Embodiment 42. The method of embodiment 41 , wherein the polar polymer is selected from the group consisting of polyethylene terephthalate, polybutylene terephthalate, and mixtures thereof.Embodiment 43. The method of embodiment 42, wherein the polar polymer is polyethylene terephthalate.Embodiment 44. The method of any of embodiments 35-43, wherein the polar polymer comprises about 5 wt.% to about 70 wt.% of the total mass of polyolefin and polar polymer present in the mixture.Embodiment 45. The method of embodiment 44, wherein the polar polymer comprises about 10 wt.% to about 65 wt.% of the total mass of polyolefin and polyester polymer present in the mixture.Embodiment 46. The method of any of embodiments 35-46, wherein the propylene polymer is selected from the group consisting of polypropylene homopolymers and propylene-ethylene random copolymers.Embodiment 47. The method of embodiment 46, wherein the propylene polymer is a propylene-ethylene random copolymer comprising about 4 wt.% to about 50 wt.% ethylene.Embodiment 48. The method of embodiment 47, wherein the propylene- ethylene random copolymer comprises about 4 wt.% to about 20 wt.% ethylene.Embodiment 49. The method of any of embodiments 35-48, wherein the epoxyfunctional copolymer is a copolymer of at least one first vinyl monomer and at least one second, epoxy-functional vinyl monomer.Embodiment 50. The method of embodiment 49, wherein the epoxy-functional copolymer is a random copolymer of at least one vinyl monomer and at least one epoxyfunctional acrylate monomer.Embodiment 51 . The method of any of embodiments 35-50, wherein the epoxyfunctional copolymer comprises about 60 wt.% to about 90 wt.% of the mass of the reactive polymeric processing aid.Embodiment 52. The method of embodiment 51 , wherein the epoxy-functional copolymer comprises about 70 wt.% to about 90 wt.% of the mass of the reactive polymeric processing aid.Embodiment 53. The method of any of embodiments 49-52, wherein the vinyl monomer is selected from the group consisting of styrene, substituted styrenes, and mixtures thereof.Embodiment 54. The method of embodiment 53, wherein the vinyl monomer is styrene.Embodiment 55. The method of any of embodiments 50-54, wherein the epoxyfunctional acrylate monomer is selected from the group consisting of glycidyl acrylate, glycidyl methacrylate, and mixtures thereof.Embodiment 56. The method of embodiment 55, wherein the epoxy-functional acrylate monomer is glycidyl methacrylate.Embodiment 57. The method of any of embodiments 35-56, wherein the mixture comprises about 0.1 wt.% to about 10 wt.% of the reactive polymeric processing aid(s), based on the total weight of the mixture.Embodiment 58. The method of embodiment 57, wherein the mixture comprises about 0.1 wt.% to about 5 wt.% of the reactive polymeric processing aid(s), based on the total weight of the mixture.Embodiment 59. The method of embodiment 58, wherein the mixture comprises about 0.25 wt.% to about 5 wt.% of the reactive polymeric processing aid(s), based on the total weight of the mixture.Embodiment 60. The method of embodiment 59, wherein the mixture comprises about 0.5 wt.% to about 5 wt.% of the reactive polymeric processing aid(s), based on the total weight of the mixture.Embodiment 61 . The method of embodiment 60, wherein the mixture comprises about 0.75 wt.% to about 5 wt.% of the reactive polymeric processing aid(s), based on the total weight of the mixture.Embodiment 62. The method of embodiment 61 , wherein the mixture comprises about 1 wt.% to about 5 wt.% of the reactive polymeric processing aid(s), based on the total weight of the mixture.Embodiment 63. The method of embodiment 58, wherein the mixture comprises about 0.1 wt.% to about 3 wt.% of the reactive polymeric processing aid(s), based on the total weight of the mixture.Embodiment 64. The method of embodiment 63, wherein the mixture comprises about 0.25 wt.% to about 3 wt.% of the reactive polymeric processing aid(s), based on the total weight of the mixture.Embodiment 65. The method of embodiment 64, wherein the mixture comprises about 0.5 wt.% to about 3 wt.% of the reactive polymeric processing aid(s), based on the total weight of the mixture.Embodiment 66. The method of embodiment 65, wherein the mixture comprises about 0.75 wt.% to about 3 wt.% of the reactive polymeric processing aid(s), based on the total weight of the mixture.Embodiment 67. The method of embodiment 66, wherein the mixture comprises about 1 wt.% to about 3 wt.% of the reactive polymeric processing aid(s), based on the total weight of the mixture.

[0038] The following examples further illustrate the subject matter described above but, of course, should not be construed as in any way limiting the scope thereof.EXAMPLES

[0039] The following general procedures and test methods were used in the examples that follow.

[0040] All polymer compositions made in the following examples were melt compounded on a 32:1 single screw extruder (SSE), a 18 mm twin-screw extruder (TSE), or a 16 mm TSE.

[0041] For polymer compositions made on the SSE, the components of the polymer composition were first bag mixed and then co-fed into the hopper of the SSE. The SSE was operated at a screw speed of 80 RPM and a temperature profile from the first zone to the die zone of: 250 °C, 260 °C, 260 °C, 260 °C, 255 °C. The extrudate exiting the die was immediately submerged in a water batch before being fed into a pelletizer.

[0042] For polymer compositions made on the 18 mm TSE, the components of the polymer composition were mixed and co-fed from the hopper of the extruder. The throughput was set to 5 kg / hr, and the extruder screw speed was set to 500 RPM. The extrusion profile used on the 18 mm TSE was the following from the first zone to the die zone: 255 °C, 260 °C, 260 °C, 260 °C, 260 °C, 260 °C, 260 °C, 250 °C. The extrudate exiting the die was immediately submerged in a water batch before being fed into a pelletizer.

[0043] For polymer compositions made on the 16 mm TSE, the components of the polymer composition were mixed and co-fed from the hopper of the extruder. The extruder was operated with a feed screw speed of 120 RPM (yielding a feed rate of approximately 2.8 kg / hr) and an extruder screw speed of 400 RPM. The extrusion profile used on the 16mmTSE was the following, from zone 1 to die zone: 250 °C, 260 °C, 260 °C, 260 °C, 255 °C. The extrudate exiting the die was immediately submerged in a water batch before being fed into a pelletizer.

[0044] The melt flow rate (MFR) of the polymer compositions was measured in accordance with ASTM D1238 at a temperature of 260 °C using a 2.16 kg mass. The resulting MFR are reported in units of grams per 10 minutes (g / 10 min).

[0045] Die swell is a measure of the degree to which a polymer extrudate expands after passing through a die orifice. The die swell ratio is the ratio between the cross section of the extrudate exiting a die orifice and the cross section of that die orifice. The average die swell ratio of the polymer compositions was measured in accordance with ASTM D3835 at a shear rate of 144 s-1and a temperature of 270 °C following a six-minute pre-heat time. The capillary rheometer used in the measurements was equipped with a 12 mm barrel and a 30:2 die. The die swell variation reported for a polymer composition is the coefficient of variation of the die swell ratio for that polymer composition, which was calculated by dividing the average die swell ratio for a polymer composition by the standard deviation of the average die swell ratio for that same polymer composition and then multiplying by 100%.

[0046] Some polymer compositions were observed using hot stage polarized optical microscopy (POM) to qualitatively assess morphology of the polymer composition. The POM assessments were conducted using a Leica DM 2700P microscope equipped with a Mettler Toledo FP82HT hot stage and Mettler Toledo FP90 control processor. A pellet collected following the extrusion of the polymer composition was carefully cut into a thin slice using a razor blade. The pellet slice was placed on a glass slide using a pair of tweezers, and the glass slide and pellet slice were placed into a hot stage equipped with a viewing window. The hot stage was then heated to 270 °C at 20 °C / min, and the temperature was held at 270 °C for approximately one minute. During the hold time, a second glass slide was placed on top of the molten pellet slice. The upper glass slide was pressed into the lower glass slide using the back end of a pair of metal tweezers. The cover on the hot stage was then closed, and the sample was cooled from 270 °C to 50 °C at 20 °C / min. The sample was then cycled between 270 °C and 50 °C as described above, and imaging was begun after the cooling cycle was initiated. Images were taken at 5x and 40x magnification directly on the stage.EXAMPLE 1

[0047] This example demonstrates the production of polymer compositions according to the invention and certain improved processability characteristics of those polymer compositions.

[0048] Six polymer compositions (Samples 1 A-1 F) were made using the SSE procedure set forth above. Samples 1 A and 1 B contained equal parts by weight of a polypropylene homopolymer (Formolene® 4100P from Formosa Plastics Corporation, U.S.A.) and a polyethylene terephthalate polymer (Bapolene® 80 from Bamberger Polymers, Inc.). Samples 1 C and 1 D contained equal parts by weight of a high density polyethylene polymer (ExxonMobil™ HD 6719.17 high density polyethylene) and a polyethylene terephthalate polymer (Bapolene® 80 from Bamberger Polymers, Inc.). Samples 1 E and 1 F contained equal parts by weight of a polypropylene homopolymer (Formolene® 41 OOP from Formosa Plastics Corporation, U.S.A.), a polyethylene polymer (please provide details of the PE used), and a polyethylene terephthalate polymer (Bapolene® 80 from Bamberger Polymers, Inc.).

[0049] Samples 1 B, 1 D, and 1 F additionally contained approximately 2 wt.% (based on the total weight of the polymer composition) of a reactive polymeric processing aid designated as “RPPA 1 .” “RPPA 1” was a reactive polymeric processing aid in the form of a comb polymer having a propylene-ethylene random copolymer backbone and an epoxyfunctional copolymer grafted to the propylene-ethylene random copolymer backbone. The propylene-ethylene random copolymer contained approximately 16 wt.% of ethylene. The epoxy-functional copolymer was a random copolymer of styrene and glycidyl methacrylate, and the epoxy-functional copolymer comprised approximately 80 wt.% of the reactive polymeric processing aid.

[0050] For each polymer composition, the die swell variation of the extrudate exiting the SSE was qualitatively assessed. Samples 1 A, 1C, and 1 E were each observed to produce extrudate having a highly variable cross-section, which is indicative of a high degree of die swell variation. Further, the SSE exhibited excessive surging behavior when these samples were processed, with large slugs of material exiting the die followed by thin strands of material. Samples 1 B, 1 D, and 1 F, which contained the reactive polymeric processing aid RPPA 1 , were each observed to produce extrudate having a more uniform cross-section, which is indicative of a low degree of die swell variation. Additionally, when Samples 1 B, 1 D, and 1 F were processed, the SSE did not exhibit the excessive surging behavior observed during the extrusion of Samples 1A, 1C, and 1 E.

[0051] Samples of the extrudate for each polymer composition were collected after water bath cooling and prior to pelletization. These strands were then photographed with a United States penny in the field of view for scale. These photographs are included as Figs. 1 -6.EXAMPLE 2

[0052] This example demonstrates the production of polymer compositions according to the invention and certain improved processability characteristics of those polymer compositions.

[0053] Four polymer compositions (Samples 2A-2D) were prepared in accordance with the 18 mm TSE procedure described above. All polymer compositions were made using three parts by weight of a polypropylene homopolymer (Formolene® 4100P from Formosa Plastics Corporation, U.S.A.) and one part by weight of a polyethylene terephthalate polymer (Bapolene® 80 from Bamberger Polymers, Inc.). Samples 2B-2D were additionally made using approximately 2 wt.% (based on the total weight of the polymer composition) of processing aid. Sample 2B utilized a commercially available maleic anhydride-grafted polypropylene random copolymer tie resin (Orevac® 18722 from SK Functional Polymer), and Sample 2C utilized a commercially available maleic anhydride- grafted ethylene octene copolymer tie resin (Amplify™ GR216 from Dow). Sample 2D was made using RPPA 1 described above in Example 1 .

[0054] After extrusion and pelletization, the samples were evaluated to measure MFR, average die swell ratio, die swell variation, chord flexural modulus, impact resistance at 23 °C, and elongation at break. The MFR, average die swell ratio, and die swell variation were determined as described above. The chord flexural modulus was measured in accordance with ISO178 except that the barrel of the extruder used in molding the samples was ramped from 250 °C (in zones 1-4) to 230 °C (in the die zone). The impact resistance at 23 °C was measured in accordance with ISO180 except that the samples were molded using the same temperature profile used in making samples for the chord flexural modulus measurements. The elongation at break was measured in accordance with ISO527 except that the samples were molded using the same temperature profile used in making samples for the chord flexural modulus measurements. The modified temperatures used for molding of the parts used for chord flexural modulus, impact resistance, and elongation at break were more suitable for molding of a sample that contained PET. The results of these measurements are set forth in Tables 1-3 below.Table 1 .

[0055] The data in Table 1 show that Sample 2B showed little change in MFR and die swell variation and a slight increase in average die swell ratio relative to the unmodified polymer blend (Sample 2A). Sample 2C showed some decrease in MFR, average die swell, and die swell variation relative to Sample 2A. Sample 2D, which was made using a reactive polymeric processing aid as described herein, exhibited an appreciable decrease in MFR and average die swell ratio relative to Sample 2A. Further, the die swell variation of Sample 2D was reduced to near zero, which is indicative of a polymer composition that is more easily processed and produces a significantly more homogeneous extrudate after processing.Table 2.

[0056] The data in Table 2 demonstrate that the use of a reactive polymeric processing aid as described herein does not deleteriously affect the physical properties of the resulting polymer composition. While Sample 2D did exhibit a lower flexural modulus, the lower stiffness is offset by improvements in the impact resistance and the elongation at break relative to the untreated polymer blend (Sample 2A).

[0057] Samples 2A, 2B, and 2D were also evaluated by POM as described above. Images from the POM evaluation are shown as Figs. 7-9. The images from the POM analysis illustrate some of the differences in the resultant morphologies of the polymer compositions. The unmodified polymer blend (Sample 2A) appeared to have much larger domains and smoother edges along the borders of the smaller domains, which are characteristic for immiscible polymer blends. The image for Sample 2B (Fig. 8) was used as a representative for the maleic anhydride-grafted tie resins as they were both very similar in appearance. The polymer compositions made with tie resins (Samples 2B and 2C) were characterized by small spherical domains scattered in the matrix, which could be seen at higher magnification. Lastly, the morphology for the polymer composition utilizing RPPA 1 (Sample 2D) was very different from the unmodified polymer blend and the tie resin modified samples (Samples 2B and 2C). The developed morphology had far fewer small spheres scattered within the matrix and elongated dispersed-phase structures, which are expected to be the domains containing PET.EXAMPLE 3

[0058] This example demonstrates the production of polymer compositions according to the invention and certain improved processability characteristics of those polymer compositions.

[0059] Five polymer compositions (Samples 3A-3E) were prepared in accordance with the 16 mm TSE procedure described above. All polymer compositions were made using equal parts by weight of a polypropylene homopolymer (Formolene® 41 OOP from Formosa Plastics Corporation, U.S.A.) and a polyethylene terephthalate polymer (Bapolene® 80 from Bamberger Polymers, Inc.). Samples 3B-3E were each additionally made using approximately 2 wt.% (based on the total weight of the polymer composition) of processing aid. Sample 3B was made using RPPA 1 described above in Example 1 . Sample 3C was made using a processing aid in the form of a comb polymer having a polypropylene homopolymer backbone onto which was grafted approximately 50 wt.% (based on the weight of the processing aid) of a copolymer of styrene, glycidyl methacrylate, and methyl methacrylate. Sample 3D was made using a processing aid in the form of a comb polymer having an ethylene butyl acrylate copolymer backbone on which was grafted a copolymer of styrene and glycidyl methacrylate. Sample 3E was made using a processing aid in the form of a comb polymer having an ethylene-octene copolymer backbone onto which was grafted a copolymer of styrene and glycidyl methacrylate.

[0060] After extrusion and pelletization, the samples were evaluated to measure MFR, average die swell ratio, and die swell variation, as described above. The results of these measurements are set forth in Table 4 below.Table 4.

[0061] The data in Table 4 show that the polymer composition made with RPPA 1 (Sample 3B) had the lowest average die swell ratio of the modified polymer compositions and the lowest die swell variation of all the polymer compositions. As before, these data are consistent with a polymer composition that is more easily processed and produces a significantly more homogeneous extrudate after processing. Further, these differences in die swell behavior are particularly striking when one considers that Samples 3C-3E had significantly higher average die swell ratios than the unmodified polymer blend (Sample 3A). In fact, the average cross-section of the extrudate for Samples 3C-3E was 84% to 96% greater than the average cross-section of the extrudate for Sample 3A. Thus, while the die swell variation of Samples 3C-3E was essentially the same as the die swell variation for Sample 3A, the absolute variation in the cross-section of the extrudate for Samples 3C-3E was nearly double that for the unmodified polymer blend and nearly twelvefold that for Sample 3B. Such significant variations in the cross-section of the extrudate would make uniform pelletization of such a polymer composition very difficult.

[0062] The differences between the results for Sample 3B and Samples 3C-3E are particularly surprising given the similar comb polymer structure of the processing aids used in Samples 3C-3E and the reactive polymeric processing aid (RPPA 1) used in Sample 3B. For example, the results for Sample 3C show that a processing aid having a similar comb polymer structure but containing a relatively low amount of copolymer (e.g., only 50 wt.% of a copolymer of styrene and glycidyl methacrylate) was unable to significantly improve the dieswell behavior of the polymer composition relative to the unmodified polymer blend. This appears to indicate that the amount of the copolymer exerts a significant influence over the processing aid’s ability to improve the polymer properties.

[0063] Similarly, the results for Samples 3D and 3E show that processing aids having similar comb polymer structures but having different backbones (e.g., an ethylene butyl acrylate copolymer backbone for Sample 3D and an ethylene octene copolymer backbone for Sample 3E) were unable to significantly improve the die swell behavior of the polymer composition relative to the unmodified polymer blend. This appears to indicate that the backbone of the copolymer also exerts a significant influence over the processing aid’s ability to improve the polymer properties.

[0064] All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein.

[0065] The use of the terms “a” and “an” and “the” and similar referents in the context of describing the subject matter of this application (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate the subject matter of the application and does not pose a limitation on the scope of the subject matter unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the subject matter described herein.

[0066] Preferred embodiments of the subject matter of this application are described herein, including the best mode known to the inventors for carrying out the claimed subject matter. Variations of those preferred embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilledartisans to employ such variations as appropriate, and the inventors intend for the subject matter described herein to be practiced otherwise than as specifically described herein. Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the present disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.

Claims

CLAIMS1 . A polymer composition comprising:(a) a polyolefin selected from the group consisting of polypropylene homopolymers, polypropylene copolymers, polyethylene homopolymers, polyethylene copolymers, and mixtures thereof;(b) a polar polymer selected from the group consisting of polyester polymers, polyamide polymers, and mixtures thereof; and(c) about 0.1 to 5 wt.% of a reactive polymeric processing aid based on the total weight of the polymer composition, the reactive polymeric processing aid comprising an epoxy-functional copolymer grafted to a propylene polymer, wherein (i) the propylene polymer is selected from the group consisting of polypropylene homopolymers and propylene-ethylene random copolymers, (ii) the epoxy-functional copolymer is a copolymer of at least one vinyl monomer and at least one epoxy-functional acrylate monomer, and (iii) the epoxy-functional copolymer comprises about 60 wt.% to about 90 wt.% of the mass of the reactive polymeric processing aid.

2. The polymer composition of claim 1 , wherein the polymer composition comprises (a) a first polyolefin selected from polypropylene homopolymers, polypropylene copolymers, and mixtures thereof and (b) a second polyolefin selected from polyethylene homopolymers, polyethylene copolymers, and mixtures thereof.

3. The polymer composition of claim 1 or claim 2, wherein the polyolefin comprises about 5 wt.% to about 80 wt.% of the total mass of polyolefin and polar polymer present in the polymer composition.

4. The polymer composition of any of claims 1-3, wherein the polar polymer is polyethylene terephthalate.

5. The polymer composition of any of claims 1-4, wherein the polar polymer comprises about 5 wt.% to about 70 wt.% of the total mass of polyolefin and polar polymer present in the polymer composition.

6. The polymer composition of any of claims 1-5, wherein the propyleneethylene copolymer comprises about 4 wt.% to about 50 wt.% ethylene.

7. The polymer composition of any of claims 1-6, wherein the epoxy-functional copolymer comprises about 60 wt.% to about 90 wt.% of the mass of the reactive polymeric processing aid.

8. The polymer composition of any of claims 1-7, wherein the vinyl monomer is selected from the group consisting of styrene, substituted styrenes, and mixtures thereof.

9. The polymer composition of any of claims 1-8, wherein the epoxy-functional acrylate monomer is selected from the group consisting of glycidyl acrylate, glycidyl methacrylate, and mixtures thereof.

10. The polymer composition of any of claims 1-9, wherein the polymer composition comprises about 1 wt.% to about 3 wt.% of reactive polymeric processing aid, based on the total weight of the polymer composition.

11. A method of making a polymer composition, the method comprising the steps of:(a) combining a polyolefin, a polar polymer, and a reactive polymeric processing aid to produce a mixture, wherein:(i) the polyolefin is selected from the group consisting of polypropylene homopolymers, polypropylene copolymers, polyethylene homopolymers, polyethylene copolymers, and mixtures thereof;(ii) the polar polymer is selected from the group consisting of polyester polymers, polyamide polymers, and mixtures thereof;(iii) the reactive polymeric processing aid comprises an epoxy-functional copolymer grafted to a propylene polymer, where the propylene polymer is selected from the group consisting of polypropylene homopolymers and propylene-ethylene random copolymers, and the epoxy-functional copolymer is a copolymer of at least one vinyl monomer and at least one epoxy-functional acrylate monomer; and(iv) the reactive polymeric processing aid comprises about 0.1 to 5 wt.% of the total weight of the mixture; and(b) melt mixing the mixture at a temperature greater than the melting points of the polyolefin and polar polymer to produce a polymer composition.

12. The method of claim 1 , wherein the mixture comprises (a) a first polyolefin selected from polypropylene homopolymers, polypropylene copolymers, and mixtures thereof and (b) a second polyolefin selected from polyethylene homopolymers, polyethylene copolymers, and mixtures thereof.

13. The method of claim 11 or claim 12, wherein the polyolefin comprises about 5 wt.% to about 80 wt.% of the total mass of polyolefin and polar polymer present in the mixture.

14. The method of any of claims 11 -13, wherein the polar polymer is polyethylene terephthalate.

15. The method of any of claims 11 -14, wherein the polar polymer comprises about 5 wt.% to about 70 wt.% of the total mass of polyolefin and polar polymer present in the mixture.

16. The method of any of claims 11 -15, wherein the propylene-ethylene copolymer comprises about 4 wt.% to about 50 wt.% ethylene.

17. The method of any of claims 11 -16, wherein the epoxy-functional copolymer comprises about 60 wt.% to about 90 wt.% of the mass of the reactive polymeric processing aid.

18. The method of any of claims 11 -17, wherein the vinyl monomer is selected from the group consisting of styrene, substituted styrenes, and mixtures thereof.

19. The method of any of claims 11 -18, wherein the epoxy-functional acrylate monomer is selected from the group consisting of glycidyl acrylate, glycidyl methacrylate, and mixtures thereof.

20. The method of any of claims 11 -19, wherein the mixture comprises about 1 wt.% to about 3 wt.% of reactive polymeric processing aid, based on the total weight of the mixture.

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