USES THEREOF

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] The present invention claims priority to US provisional application number 62/685,342 filed on June 15, 2018.

BACKGROUND OF THE INVENTION

A. Field of the Invention

[0002] The invention generally concerns multilayered polymeric structures. These structures can be polypropylene (PP) and polyethylene (PE) multilayered structures where the polypropylene and/or polyethylene are characterized by a narrow molecular weight distribution.

B. Description of Related Art

[0003] Conventional propylene and/or polyethylene polymeric materials have long been used in processes like thermoforming, blow moulding, coating, etc., to make end-use articles such as films, bottles, fuel tanks, medical devices, food containers, and the like. However, if the process included blown films process, extrusion/injection/stretch blow molding of large hollow devices with 3-dimensional complexity (e.g., bottles with a handle), or thermoforming (either pre-stretch or plug assisted), these production processes require the polypropylene and polyethylene to have high melt strengths, which can be achieved by increasing molecular weight, broadening of molecular weight distribution of the polymers, and/or introduction of long chain branching. Molecular weight and molecular weight distribution can be modified in the polymerization process itself by choosing particular process conditions. Nonetheless, typical propylene polymer resins, even those having high molecular weight and broad molecular weight distribution, often cannot provide commercially desired levels of melt strength and/or barrier properties without additional processing and/or inclusion of additives. Production of polypropylene grades with long chain branches is possible but complicated, requiring the copolymerization of propylene with specific comonomer (e.g., long dienes), use of specific single site catalysts or combination of such catalysts, or specific treatment of the fluff (irradiation, palletization with high amount of peroxide (e.g., peroxydicarbonate products), pelletization with peroxide and short molecules containing double bonds, and the like. [0004] Attempts to reduce the oxygen permeability of polyolefin films for packaging applications have been described. By way of example, Mauri et al. (Journal of Polymer Science, Part B: Polymer Physics, 2018, 56, 520-531 ) describes PE/PP multilayered thin (25 microns) films with 50% polyethylene and 50% polypropylene resulted in an increase in oxygen permeability. To reduce the oxygen permeability layers of less permeable polymers such as ethylene vinyl alcohol copolymer can be added.

[0005] While various approaches have been tried to improve the physical properties of polymers used for moulding, extrusion, and other processes, there is still a need for polymeric structures that have improved melt strength properties and oxygen barrier properties. There is also a need for polymeric structures that have improved flame retardant properties such as improved anti-dripping properties.

SUMMARY OF THE INVENTION

[0006] A discovery has been made that provides a solution to at least some of the problems associated with melt strength and barrier properties of polymers used in extrusion, foaming, film blowing, blow moulding, or thermo-forming applications. The discovery is premised on a polyethylene and polypropylene multilayered structure where at least one of the polyethylene and polypropylene (preferably both) used to produce the layers have a narrow molecular weight distribution. The narrow molecular weight distribution can be achieved by making the polyethylene and polypropylene using single site catalysts. In some embodiments, a polypropylene that has a higher crystallization temperature than the polyethylene is also used. Notably, and as illustrated in a non-limiting manner in the examples, the multilayered polymeric structures of the present invention have a higher melt strength when compared with single layer polypropylene materials and multilayered structures made from polymers with broader molecular weight distribution like those obtained when the polymerization is performed with multisite type catalysts ( e.g ., Ziegler- Natta catalysts). Even more notably, the higher melt strength is achieved without melt strength additives (e.g., phthalic acid diethyl esters melt strength additives, metal oxides, etc.) and/or additional polymers (e.g., polyethylene terephthalate, polylactic acid, acrylic polymers and copolymers, etc.). Still further, the multilayered polymeric structures of the present invention can have reduced oxygen permeability coefficient (P02) that is better than that of multilayered structures made from polymers with broader molecular weight distribution. Without wishing to be bound by theory, it is believed that using the narrow molecular weight distribution polyethylene and/or the narrow molecular weight distribution polypropylene to produce a multilayered polymeric structure where at least a portion of the polyethylene layer is in direct contact with a polypropylene layer such that an interface is formed between the polyethylene and polypropylene layers results in a higher density of interfacial entanglements at the interfaces of the polymeric layers. This is believed to produce the increased melt strength and/or P02 barrier properties of the polymeric structures of the present invention. Notably, annealing conditions do not have to be used (but can be if so desired) in the context of the present invention. Surprisingly, an improvement of the anti- dripping properties was demonstrated on the polyethylene and polypropylene multilayered structure according to the invention.

[0007] In one aspect of the current invention, multilayered polymeric structures are disclosed.

A multilayered polymeric structure can include (a) at least one polyethylene (PE) layer, and (b) at least one polypropylene (PP) layer that is in direct contact with at least a portion of the polyethylene layer such that an interface is formed between the polyethylene and polypropylene layers. The polyethylene of the at least one polyethylene layer and/or the polypropylene of the at least one polypropylene layer is characterized by a narrow molecular weight distribution (Mw/Mn) and it can be formed from a single-site catalyzed polyethylene or a single-site catalyzed PP, respectively.

[0008] In other terms, according to a first aspect, the invention provides a multilayered polymeric structure comprising:

(a) at least one polyethylene layer comprising a polyethylene; and

(b) at least one polypropylene layer comprising a polypropylene;

is remarquable in that at least one polypropylene layer is in direct contact with at least a portion of the polyethylene layer such that an interface is formed between the polyethylene and polypropylene layers; in that the polyethylene of the at least one polyethylene layer and/or the polypropylene of the at least one polypropylene layer has a narrow molecular weight distribution ranging from 2 to 4; and in that the polypropylene of the at least one polypropylene layer has a crystallization temperature that is equal or higher than the crystallization temperature of the polyethylene of the at least one polyethylene layer.

[0009] With preference, both the polyethylene of the at least one polyethylene layer and the polypropylene of the at least one polypropylene layer have a narrow molecular weight distribution ranging from 2 to 4. [0010] In an embodiment, at least one of the polyethylene of the at least one polyethylene layer and/or of the polypropylene of the at least one polypropylene layer has a molecular weight distribution ranging from 2 to 4, preferably ranging to 2.1 to 3.9, more preferably ranging from 2.3 to 3.7, and most preferably from 2.5 to 3.5. With preference, the polyethylene of the at least one polyethylene layer and the polypropylene of the at least one polypropylene layer have each a molecular weight distribution ranging from 2 to 4, preferably ranging to 2.1 to 3.9, more preferably ranging from 2.3 to 3.7, and most preferably from 2.5 to 3.5.

[0011] According to the invention, the polypropylene of the at least one polypropylene layer has a crystallization temperature that is equal or higher than the crystallization temperature of the polyethylene of the at least one polyethylene layer. With preference, the polypropylene of the at least one polypropylene layer has a crystallization temperature that is higher than the crystallization temperature of the polyethylene of the at least one polyethylene layer. In an embodiment, the polypropylene has a crystallization temperature that is higher than the crystallization temperature of the polyethylene of at least 0.1 °C and at most 15°C, preferably from 0.5 °C to 10°C, more preferably from 1 °C to 8°C.

[0012] In another preferred embodiment that complementary to the preceding one, the difference between the crystallization temperature of the polypropylene of the at least one polypropylene layer and the crystallization temperature of the polyethylene of the at least one polyethylene layer is at most 15 °C; preferably at most 12°C, more preferably at most 10°C, and even more preferably at most 8°C.

[0013] In an embodiment, the polyethylene and/or the polypropylene having a narrow molecular weight distribution are derived from a single site catalyzed polymerization preferably a metallocene catalyzed polymerization. With preference, the polyethylene is a single-site catalyzed polyethylene and/or the polypropylene is a single site-catalyzed polypropylene; more preferably, the polyethylene is a metallocene-catalyzed polyethylene and/or the polypropylene is a metallocene-catalyzed polypropylene. In other words, in a preferred embodiment, the polyethylene of the at least one polyethylene layer is a metallocene-catalyzed polyethylene and/or the polypropylene of the at least one polypropylene layer is a metallocene-catalyzed polypropylene.

[0014] By way of example, the polyethylene can be a single-site catalyzed polymer, the polypropylene can be a single-site catalyzed polymer, or both the polyethylene and polypropylene can be single-site catalyzed polymers. In some instances, the polypropylene and/or polyethylene are each selected from a metallocene catalyzed polymer. The polyethylene and the polypropylene can each have a molecular weight distribution (Mw/Mn) of 2 to 4.5, preferably 2 to 4. In some instances, each polymer has an Mw/Mn of 2 to 4.

[0015] In some embodiments, one of the polypropylene or the polyethylene is made using a Ziegler-Natta catalyst. In some embodiments, the polyethylene is made using a chromium catalyst. Thus, in an embodiment, the multilayered polymeric structure according to the invention can have a polyethylene having a narrow molecular weight distribution ranging from 2 to 4 in combination with a polypropylene having a larger molecular weight distribution of above 4, preferably above 5, more preferably above 6. In such a case, the polypropylene can be produced using a Ziegler-Natta catalyst. In another embodiment, the multilayered polymeric structure according to the invention can have a polypropylene having a narrow molecular weight distribution ranging from 2 to 4 in combination with a polyethylene having a larger molecular weight distribution of above 4, preferably above 5, more preferably above 6. In such a case, the polyethylene can be produced using a Ziegler-Natta catalyst or a chromium catalyst.

[0016] In some embodiments, the polyethylene is low-density polyethylene (LDPE), a linear low-density polyethylene (LLDPE) polymer or a medium density polyethylene (MDPE). In another embodiment, the polyethylene is a high-density polyethylene (HDPE). The polyethylene can be a copolymer of ethylene and one or more comonomer(s) having from 1 to 12 carbon atoms. The more preferred comonomer is hexene.

[0017] With preference, the polyethylene of the at least one polyethylene layer has a density ranging from 0.900 g/cm ³ to 0.980 g/cm ³ as determined according to ISO 1 183; and/or has an MFI ranging from 0.4 g/10 min to 8 g/10 min, as determined according to ISO 1 133 at a temperature of 190 °C with a load of 2.16 kg; with preference, ranging from 1 g/10 min to 6 g/10 min.

[0018] In an embodiment, the polyethylene is a linear low-density polyethylene (LLDPE) having a density ranging from 0.900 g/cm ³ to 0.930 g/cm ³ as determined according to ISO 1 183; and/or is a linear low-density polyethylene being a copolymer of ethylene and one or more comonomer(s) having from 1 to 12 carbon atoms; preferably the comonomer is 1 -hexene.

[0019] In an embodiment, the polyethylene is a low-density polyethylene (LDPE) having a density ranging from 0.900 g/cm ³ to 0.930 g/cm ³ as determined according to ISO 1 183; and/or is a low-density polyethylene being a copolymer of ethylene and one or more comonomer(s) having from 1 to 12 carbon atoms; preferably the comonomer is 1 -hexene.

[0020] In another embodiment, the polyethylene is a high-density polyethylene (HDPE) having a density ranging from 0.940 g/cm ³ to 0.980 g/cm ³ as determined according to ISO 1 183; and/or is a high-density polyethylene being a copolymer of ethylene and one or more comonomer(s) having from 1 to 12 carbon atoms; preferably the comonomer is 1 -hexene.

[0021] In an embodiment, the polyethylene is a medium-density polyethylene (MDPE) having a density ranging from 0.930 g/cm ³ to 0.940 g/cm ³ as determined according to ISO 1 183; and/or is a medium-density polyethylene being a copolymer of ethylene and one or more comonomer(s) having from 1 to 12 carbon atoms; preferably the comonomer is 1 -hexene.

[0022] With preference, the polypropylene of the at least one polypropylene layer is a propylene homopolymer; and/or has an MFI ranging from 0.8 g/10 min to 30 g/10 min, as determined according to ISO 1 133 at a temperature of 230 °C with a load of 2.16 kg; with preference, ranging from 2 g/10 min to 25 g/10 min.

[0023] In an embodiment, the polypropylene of the at least one polypropylene layer and polyethylene of the at least one polyethylene layer are selected in order to have the MFI of the polypropylene as determined according to ISO 1 133 at a temperature of 230 °C with a load of 2.16 kg being equal to or at most eight time higher than MFI of the polyethylene as determined according to ISO 1 133 at a temperature of 190 °C with a load of 2.16 kg; preferably the MFI of the polypropylene as determined according to ISO 1133 at a temperature of 230 °C with a load of 2.16 kg is at least two time and/or at most five time higher than MFI of the polyethylene as determined according to ISO 1 133 at a temperature of 190 °C with a load of 2.16 kg.

[0024] In an embodiment, the polyethylene and/or the polypropylene having a narrow molecular weight distribution are derived from a single site catalyzed polymerization preferably a metallocene catalyzed polymerization, and the polypropylene is a nucleated polypropylene, and the multilayer structure has an actual oxygen permeability coefficient (P02) that is less than its predicted P02.

[0025] The multilayered polymeric structure can have an actual oxygen permeability coefficient (P02) that is less than its predicted P02, and/or a melt strength that is greater than the melt strength of a comparable polymeric structure absent the narrow molecular weight polyethylene layer ( e.g ., a P02 of less than 0.1 (mxcm ³ )/(m ² x24hrsxPa) for the multilayered structure of the present invention versus greater than 0.1 (mxcm ³ )/(m ² x24hrsxPa) for a comparative sample).

[0026] In an embodiment, the multilayered polymeric structure comprises a melt strength that is greater than the melt strength of a comparable polymeric structure absent the polypropylene layer.

[0027] In a preferred embodiment, the multilayered polymeric structure is consisting of polyethylene and polypropylene. Thus, the invention provides a multilayered polymeric structure comprising:

(a) at least one polyethylene layer consisting of a polyethylene; and

(b) at least one polypropylene layer consisting of a polypropylene;

is remarkable in that at least one polypropylene layer is in direct contact with at least a portion of the polyethylene layer such that an interface is formed between the polyethylene and polypropylene layers; in that the polyethylene of the at least one polyethylene layer and/or the polypropylene of the at least one polypropylene layer have a narrow molecular weight distribution ranging from 2 to 4; and in that the polypropylene of the at least one polypropylene layer has a crystallization temperature that is equal or higher than the crystallization temperature of the polyethylene of the at least one polyethylene layer; with preference, the polyethylene is a high- density polyethylene having a density ranging from 0.940 g/cm ³ to 0.980 g/cm ³ as determined according to ISO 1183; or the polyethylene is a low-density polyethylene having a density ranging from 0.900 g/cm ³ to 0.930 g/cm ³ as determined according to ISO 1 183; or the polyethylene is a medium-density having a density ranging from 0.930 g/cm ³ to 0.940 g/cm ³ as determined according to ISO 1 183; or polyethylene is a linear low-density polyethylene having a density ranging from 0.900 g/cm ³ to 0.930 g/cm ³ as determined according to ISO 1 183.

[0028] The polyethylene layer and/or the polypropylene layer can further include one or more additives. Non-limiting examples of additives include a nucleating agent, an anti-blocking agent, an antistatic agent, an antioxidant, a neutralizing agent, a blowing agent, a dye, a flame retardant, a filler, an impact modifier, a mold release agent, an oil, another polymer, a pigment, a processing agent, a reinforcing agent, a clarifying agent, a slip agent, a flow modifier, a stabilizer, an UV resistance agent, and combinations thereof. Non-limiting examples of nucleating additives can include talc, alkali metal benzoate salts (e.g., lithium benzoate, sodium benzoate, and the like), and sorbitol derivatives. [0029] The multilayered structure can have a plurality of alternating polyethylene and polypropylene layers ( e.g ., 2, 50, 100, 150, efc.); preferably at least 50 alternating polyethylene layers and polypropylene layers, more preferably at least 100 alternating polyethylene layers and polypropylene layers, even more preferably at least 150 alternating polyethylene layers and polypropylene layers, and most preferably at least 200 alternating polyethylene layers and polypropylene layers, or at least 500 alternating polyethylene layers and polypropylene layers. With preference multilayered structure has at most 20,000 alternating polyethylene layers and polypropylene layers, preferably at most 10,000 alternating polyethylene layers and polypropylene layers, or at most 7,000 alternating polyethylene layers and polypropylene layers more preferably at most 5,000 alternating polyethylene layers and polypropylene layers, at most 3,000 alternating polyethylene layers and polypropylene layers even more preferably at most 2,000 alternating polyethylene layers and polypropylene layers; and most preferably at most 1 ,000 alternating polyethylene layers and polypropylene layers.

[0030] In certain embodiments, the multilayered structure has at least 4 layers (e.g., 4, 50, 100, 150, etc.). In some embodiments, the multilayered structure has 50 to 10000 polyethylene layers and 50 to 10,000 polypropylene layers or more. With preference, the multilayered structure has 50 to 10,000 linear low-density polyethylene layers and 50 to 10,000 polypropylene layers. In an embodiment, the multilayered structure has 50 to 10,000 high-density polyethylene layers and 50 to 10,000 polypropylene layers.

[0031] Thus, in a preferred embodiment, the invention provides a multilayered polymeric structure comprising:

(a) at least one polyethylene layer comprising a polyethylene; and

(b) at least one polypropylene layer comprising a polypropylene;

is remarquable in that at least one polypropylene layer is in direct contact with at least a portion of the polyethylene layer such that an interface is formed between the polyethylene and polypropylene layers; in that the polyethylene of the at least one polyethylene layer and/or the polypropylene of the at least one polypropylene layer has a narrow molecular weight distribution ranging from 2 to 4; in that the polypropylene of the at least one polypropylene layer has a crystallization temperature that is equal or higher than the crystallization temperature of the polyethylene of the at least one polyethylene layer; and in that the multilayered polymeric structure is having at least 50 alternating polyethylene layers and polypropylene layers. With preference, the multilayered polymeric structure is having from 50 to 20,000 alternating polyethylene layers and polypropylene layers; preferably from 100 to 10,000 alternating polyethylene layers and polypropylene layers; more preferably from 150 to 7,000 alternating polyethylene layers and polypropylene layers; even more preferably from 200 to 5,000 alternating polyethylene layers and polypropylene layers; and most preferably from 500 to 3,000 alternating polyethylene layers and polypropylene layers.

[0032] The minimum thickness of any individual layer is 5 nm; preferably at least 10 nm, more preferably at least 50 nm, even more preferably at least 100 nm and most preferably at least 1 pm.

[0033] In one instance, the multilayered structure only contains polyethylene and polypropylene. Said another way, the multilayered structure is absent tensile property additives and/or barrier additives or additional polymers. The multilayered structure can include antioxidants, light stabilizers, etc.

[0034] In an embodiment, the multilayered polymeric structure comprises:

- from 40 to 60 wt.% of polyethylene based on the total weight of both the polyethylene and the polypropylene in the multilayered polymeric structure; and

- from 60 to 40 wt.% of polypropylene based on the total weight of both the polyethylene and the polypropylene in the multilayered polymeric structure.

[0035] Preferably, the multilayered polymeric structure comprises from, 42 to 58 wt.% of polyethylene based on the total weight of both the polyethylene and the polypropylene in the multilayered polymeric structure; more preferably from 45 to 55 wt.%; even more preferably, from 48 to 52 wt. %; and most preferably 50 wt.%.

[0036] Preferably, the multilayered polymeric structure comprises from, 58 to 42 wt.% of polypropylene based on the total weight of both the polyethylene and the polypropylene in the multilayered polymeric structure; more preferably from 55 to 45 wt.%; even more preferably, from 52 to 48 wt. %; and most preferably 50 wt.%.

[0037] In second aspect of the invention, methods of making the multilayered polymeric structures of the present invention are described. A method can include (a) extruding a polyethylene and a polypropylene, and (b) forming at least one polyethylene layer and at least one polypropylene layer that is in direct contact with at least a portion of the polyethylene layer such that an interface is formed between the polyethylene and polypropylene layers. At least one of the polyethylene and/or of the polypropylene is characterized by a narrow molecular weight distribution ranging from 2 to 4 and the polypropylene have a crystallization temperature that is higher than or equal to the crystallization temperature of the polyethylene; with preference, the difference between the crystallization temperature of the polypropylene and the crystallization temperature of the polyethylene is at most 15 °C.

[0038] Therefore, with preference, the invention provides a method of making the multilayered polymeric structure of the first aspect, the method comprising:

(a) extruding a polyethylene and a polypropylene, wherein at least one of the polyethylene or the polypropylene is a single-site catalyzed polymer and has a narrow molecular weight distribution ranging from 2 to 4; and

(b) forming at least one polyethylene layer and at least one polypropylene layer that is in direct contact with at least a portion of the polyethylene layer such that an interface is formed between the polyethylene and polypropylene layers,

wherein the polypropylene has a crystallization temperature higher than or equal to the crystallization temperature of the polyethylene; with preference, the polypropylene has a crystallization temperature higher than the polyethylene and/or the difference between the crystallization temperature of the polypropylene and the crystallization temperature of the polyethylene is at most 15 °C.

[0039] According to a third aspect, the invention provides a material for producing a plastic film via cast or blown film extrusion, a container produced by extrusion molding process, a hollow container produced by extrusion, injection, or stretch blow molding, a device produced by thermoforming, or a foam produced via foaming process can include a multilayered polymeric structure of the present invention. In another embodiment, a hygienic film, an oxygen barrier film for food packaging, or a polymeric foamed sheet can include a multilayered polymeric structure of the present invention.

[0040] In an embodiment, the invention provides a film comprising the multilayered polymeric structure and/or the material of the present invention, wherein the film has a thickness from 0.1 to 1 mm; and/or wherein each layer has a thickness of at least 5 nm, with preference at least 1 pm.

[0041] According to a fourth aspect, the invention provides a method of improving the oxygen (O2) barrier and/or melt strength property of polyethylene (PE) or polypropylene (PE) are also described. A method can include contacting a portion of the polyethylene with the polypropylene such that an interface can be formed between the polyethylene and the polypropylene, where at least one of the polyethylene or the polypropylene is characterized by a narrow molecular weight distribution ranging from 2 to 4. In some embodiments, both the polyethylene and polypropylene are both characterized by a narrow molecular weight distribution. A method of improving the oxygen barrier and/or melt strength property of polyethylene or polypropylene, can comprise contacting a portion of the polyethylene with the polypropylene such that an interface is formed between the polyethylene and the polypropylene, wherein at least one of the polyethylene or the polypropylene is a single-site catalyzed polymer; wherein both the polyethylene and the polypropylene each have a narrow molecular weight distribution ranging from 2 to 4 and the polypropylene has a crystallization temperature higher than or equal to the crystallization temperature of the polyethylene; with preference, the difference between the crystallization temperature of the polypropylene and the crystallization temperature of the polyethylene is at most 15 °C; preferably at most 10°C.

DETAILLED DESCRIPTION OF THE INVENTION

[0042] The following includes definitions of various terms and phrases used throughout this specification.

[0043] The phrase“melt flow index” (MFI) refers to the measurement of the ease of flow of the melt of a polymer or blend.

[0044] The phrase“melt strength” refers to an engineering measurement of the extensional viscosity of the molten polymer and is the maximum tension that can be applied to the melt without it breaking. Extensional viscosity is measured as described in the testing methods part.

[0045] The phrase“molecular weight distribution (MWD or Mw/Mn)” refers to the weight average molecular weight (Mw) divided by the number average molecular weight (Mn). MWD can be measured using gel permeation chromatography (GPC). The samples can be dissolved in 1 ,2,4-trichlorobenzene. The resulting solution can then be injected into a gel permeation chromatograph and analyzed under conditions well-known in the polymer industry as exemplified in the testing methods part.

[0046] The terms“about” or“approximately” are defined as being close to as understood by one of ordinary skill in the art. In one non-limiting embodiment, the terms are defined to be within 10%, preferably within 5%, more preferably within 1 %, and most preferably within 0.5%. [0047] The terms“wt.%”,“vol.%”, or“mol.%” refers to a weight percentage of a component, a volume percentage of a component, or molar percentage of a component, respectively, based on the total weight, the total volume of material, or total moles, that includes the component. In a non-limiting example, 10 grams of a component in 100 grams of the material is 10 wt.% of the component.

[0048] The term“substantially” and its variations are defined to include ranges within 10%, within 5%, within 1 %, or within 0.5%.

[0049] The terms“inhibiting” or“reducing” or“preventing” or“avoiding” or any variation of these terms, when used in the claims and/or the specification includes any measurable decrease or complete inhibition to achieve a desired result.

[0050] The term“effective,” as that term is used in the specification and/or claims, means adequate to accomplish a desired, expected, or intended result.

[0051] The use of the words“a” or“an” when used in conjunction with any of the terms “comprising,”“including,”“containing,” or“having” in the claims, or the specification, may mean “one,” but it is also consistent with the meaning of“one or more,”“at least one,” and“one or more than one.”

[0052] The words “comprising” (and any form of comprising, such as “comprise” and “comprises”),“having” (and any form of having, such as“have” and“has”),“including” (and any form of including, such as“includes” and“include”) or“containing” (and any form of containing, such as“contains” and“contain”) are inclusive or open-ended and do not exclude additional, unrecited elements or method steps. The terms“comprising”,“comprised” and“comprised of also includes the terms“consisting of”.

[0053] The multilayered polymeric structures of the present invention can“comprise,”“consist essentially of,” or“consist of” particular ingredients, components, compositions, etc. disclosed throughout the specification. With respect to the transitional phrase“consisting essentially of,” in one non-limiting aspect, a basic and novel characteristic of the multilayered polymeric structures of the present invention are (1 ) their abilities to be formed into articles of manufacture (2) their increased melt strength when compared with the melt strength of pure polyethylene or polypropylene, and/or (3) an actual oxygen permeability coefficient (P02) that is less than its predicted P02. [0054] Other objects, features, and advantages of the present invention will become apparent from the following figures, detailed description, and examples. It should be understood, however, that the figures, detailed description, and examples, while indicating specific embodiments of the invention, are given by way of illustration only and are not meant to be limiting. Additionally, it is contemplated that changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. In further embodiments, features from specific embodiments may be combined with features from other embodiments. For example, features from one embodiment may be combined with features from any of the other embodiments. In further embodiments, additional features may be added to the specific embodiments described herein.

[0055] The terms“polypropylene” (PP) and“propylene polymer” may be used synonymously. The term “polypropylene” encompasses homopolymer of propylene as well as copolymer of propylene which can be derived from propylene and one or more comonomers selected from the group consisting of ethylene and C4-C20 alpha-olefins, such as 1 -butene, 1 -pentene, 4-methyl- 1-pentene, 1 -hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1- octadecene and 1-eicosene.

[0056] The terms“polyethylene” (PE) and“ethylene polymer” may be used synonymously. The term“polyethylene” encompasses homopolymer of ethylene as well as copolymer of ethylene which can be derived from ethylene and one or more comonomers selected from the group consisting of C3-C20 alpha-olefins, such as propylene, 1 -butene, 1-pentene, 4-methyl-1-pentene, 1 -hexene, 1 -octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1 -octadecene and 1- eicosene.

[0057] Unless stated otherwise, a reference to a polyethylene is a reference to the polyethylene of the at least one polyethylene layer. Similarly, a reference to a polypropylene is a reference to the polypropylene of the at least one polypropylene layer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Advantages of the present invention may become apparent to those skilled in the art with the benefit of the following detailed description and upon reference to the accompanying drawings. [0059] FIG. 1 is a schematic of a co-extrusion process to prepare a multilayered polymeric structure of the present invention.

[0060] FIG. 2A-2C are atomic force microscopy (AFM) images of comparative multilayered structure (2A) and multilayered structures of the present invention (2B and 2C).

[0061] FIG. 3 are differential scanning calorimetry (DSC) scans of the comparative multilayered structure (bottom scan), and multilayered structures of the present invention (middle and top scans).

[0062] FIGS. 4A-4C show the extensional viscosity for the comparative multilayered structure (4A) and the multilayered structures of the present invention (4B and 4C) with polypropylene and polyethylene used for each sample.

[0063] FIGS. 5A-5D show the engineering stress-strain properties of the individual polymers and the multilayered structures of the present invention and the comparative multilayered structure. FIG. 5A shows the engineering stress-strain curve for the comparative multilayered structure. FIGS. 5B and 5C show the engineering stress-strain curve for the multilayered structures of the present invention. FIG. 5D shows the tear strength of the comparative multilayered structure and the multilayered structures of the present invention.

[0064] FIGS. 6A and 6B show the O2 barrier properties of the multilayered structures of the present invention and the comparative multilayered structure (FIG. 6A) and the differential of the barrier properties (FIG. 6B).

[0065] FIG. 7 is a picture of an installation to conduct a dripping test.

[0066] While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings. The drawings may not be to scale.

[0067] A discovery has been made that provides a solution to at least some of the problems associated with producing polyethylene and polypropylene multilayered structures. The solution is premised on using polyethylene characterized by a narrow molecular weight distribution and/or a polypropylene characterized by a narrow molecular weight distribution to produce a multilayered polymeric structure where at least a portion of the polyethylene layer is in direct contact with a polypropylene layer such that an interface is formed between the polyethylene and polypropylene layers.

[0068] These and other non-limiting aspects of the present invention are discussed in further detail in the following sections.

A. Materials

1. Polymers

[0069] The polymers used in the polymer structures of the present invention can include polyolefins. Polyolefins can be prepared by any of the polymerization processes, which are in commercial use ( e.g ., a“high pressure” process, a slurry process, a solution process and/or a gas phase process. Polymerization processes can include polymerization of reactants in a sequence of reactors, leading to multi-modal polyolefin structures). At least one of the polyolefins (e.g., either the polyethylene or the polypropylene, but preferably both) are characterized by a narrow molecular weight distribution polymer property that can be achieved using any of the known single site catalysts (e.g., metallocene catalysts, and the like). Non-limiting examples of polyolefins include polypropylenes and polyethylenes.

[0070] Polyethylenes can include homopolymers of ethylene or copolymers of ethylene with at least one alpha-olefin (e.g., 1 -butene, 1 -pentene, 1 -hexene, 1-octene and the like). Non-limiting examples of polyethylenes include low-density polyethylene (LDPE), a linear low-density polyethylene (LLDPE), a medium density polyethylene (MDPE), a high-density polyethylene (HDPE), an ethylene copolymer, or blends thereof. Polypropylenes can include homopolymers of propylene, copolymers of propylene and other olefins, and terpolymers of propylene, ethylene, and butene, a longer alpha-olefin or a diene. Impact copolymers, corresponding to a blend of homopolypropylene (or of a copolymer of propylene and a few other olefins) with an elastomeric phase (like e.g., an ethylene-propylene rubber phase) can be used.

[0071] The polypropylene grade can be a“straight reactor” grade or a“controlled rheology” grade. A controlled rheology grade polypropylene is one that has been further processed (e.g., through a degradation process) to produce a polypropylene with a targeted high melt flow index (MFI), lower molecular weight, and/or a narrower molecular weight distribution than the starting polypropylene. Narrow molecular weight distribution polymers (e.g., single site catalyst polymers) are available from commercial sources. [0072] A non-limiting example of commercial polyolefins having a narrow molecular weight distribution are the LUMICENE® polyethylenes and polypropylenes manufactured by TOTAL Petrochemicals (France).

[0073] The polypropylene and/or polyethylene can have a narrow molecular weight distribution (MWD). In some embodiments, the MWD can be (Mw/Mn) ranging from 2 to 4.5, preferably ranging from 2 to 4, more preferably ranging to 2.1 to 3.9, even more preferably ranging from 2.3 to 3.7, and most preferably from 2.5 to 3.5. With preference, the polyethylene and the polypropylene have each a molecular weight distribution ranging from 2 to 4, preferably ranging to 2.1 to 3.9, more preferably ranging from 2.3 to 3.7, and most preferably from 2.5 to 3.5

[0074] In some embodiments, the MWD is at least, equal to, or between any two of 2, 2.25., 2.5, 2.75, 3, 3.25, 3.5, 3.75, 4, 4.25, and 4.5. In some embodiments, the MWD of both the polyethylene or polypropylene is 2 to 4.5, or 2 to 4, or at least, equal to, or between any two of 2, 2.1 , 2.2., 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1 , 3.2, 3.3., 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4.0, 4.1 , 4.2, 4.3, 4.4, and 4.5. MWD can be obtained using gel permeation methodology known in the polymer industry.

[0075] Properties of polyethylene characterized by a narrow molecular weight distribution can include density and melt flow index. The density and MFI can be any range or value. In some instances, a polyethylene having a narrow molecular weight distribution can have a density of at least 0.920 g/cm ³ or at least, equal to, or between any two of 0.900, 0.905, 0.10, 0.915, 0.920, 0.925, 0.930, 0.935, 0.940, 0.950, 0.960, 0.970, and 0.980 g/cm ³ and/or the MFI of the polyethylene can be at least 0.4 g/10 min up to 8.0 g/10 min, or at least, equal to, or between any two of 0.4, 0.5, 0.6, 0.65, 0.7, 0.75, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 6.0, 6.5, 7.0, 7.5, and 8.0 g/10 min.

[0076] In an embodiment, the polyethylene has an MFI ranging from 0.4 g/10 min to 8 g/10 min, as determined according to ISO 1 133 at a temperature of 190 °C with a load of 2.16 kg; preferably ranging from 0.5 to 7 g/10 min, more preferably ranging from 1 to 6 g/10 min, more preferably ranging from 2 to 5 g/10 min, and most preferably ranging from 3 to 4 g/10 min.

[0077] The polyethylene can be selected from a HDPE, a LLDPE, a LDPE, a MDPE, or any mixture thereof. With preference the polyethylene is selected from a HDPE and/or a LLDPE. [0078] The monomodal or multimodal HDPE characterized by a narrow molecular weight distribution can have properties such as an MFI and density. The density and MFI can be any range or value. In some instances, the density of the monomodal and/or multimodal HDPE can be at least 0.940 g/cm ³ , or at least, equal to, or between any two of 0.940, 0.945, 0.950, 0.955, 0.960, and 0.965 g/cm ³ . In some embodiments, the HDPE is monomodal. In some instances, an MFI of monomodal HDPE can be at least 0.1 g/10 min up to 1000 g/10 min. The preferred MFI values ( e.g for film production) are ranging between 0.4 g/10 min and maximum 8.0 g/10 min or at least, equal to, or between any two of 0.4, 0.5, 1.0, 1 .5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5 and 8.0 g/10 min. In some embodiments, the HDPE is multimodal. Multimodal HDPE can have an MFI of at least 0.1 g/10 min up to 1000 g/10 min. The preferred MFI values (e.g., for film production) are ranging between 0.4 g/10 min and maximum 8 g/10 min, or at least, equal to, or between any two of 0.4, 0.5, 0.75, 1 .0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.5, 2.75, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5 and 8.0 g/10 min.

[0079] The monomodal and multimodal LLDPE characterized by a narrow molecular weight distribution can have properties such as an MFI and density. The density and MFI can be any range or value. In some instances, the LLDPE can have a density of at least 0.900 g/cm ³ , or at least, equal to or between any two of 0.900 g/cm ³ , 0.905 g/cm ³ , 0.910 g/cm ³ , 0.915 g/cm ³ , 0.920 g/cm ³ , 0.925 g/cm ³ , and 0.930 g/cm ³ . MFI of LLDPE can be at least 0.1 g/10 min and maximum 1000 g/10 min. The preferred MFI values (e.g., for film production) are ranging between 0.4 g/10 min and maximum 8 g/10 min, or at least, equal to, or between any two of 0.4, 0.5, 0.6, 0.7, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.5, 2.75, 3.0, 4.0, 5.0, 6.0, 7.0 and 8.0 g/10 min. LDPE can have a melting temperature between 100 and 120 °C, or at least, equal to, or between 100, 1 10, 1 15 and 120 °C. In some embodiments, the (L)LDPE is multimodal. Multimodal (L)LDPE can have an MFI of at least 0.1 g/10 min. and maximum 1000 g/10 min. The preferred MFI values (e.g. for film production) are ranging between 0.4 g/10 min and maximum 8 g/10 min, or at least, equal to, or between any two of 0.4, 0.5, 0.6, 0.7, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.5, 2.75, 3.0, 4.0, 5.0, 6.0, 7.0 and 8.0 g/10 min.

[0080] The monomodal and/or multimodal MDPE characterized by a narrow molecular weight distribution can have properties such as an MFI and density. The density and MFI can be any range or value. In some instances, MDPE can have a density of at least 0.930 g/cm ³ , or at least, or equal to 0.930 g/cm ³ , 0.935 g/cm ³ , and 0.940 g/cm ³ . MFI of MDPE can be at least 0.1 g/10 min and maximum 1000 g/10 min. The preferred MFI values (e.g., for film production) are ranging between 0.4 g/10 min and maximum 8 g/10 min, or at least, equal to, or between any two of 0.4, 0.5, 0.6, 0.7, 0.75, 1 .0, 1.25, 1.5, 1 .75, 2.0, 2.25, 2.5, 2.75, 3.0, 4.0, 5.0, 6.0, 7.0 and 8.0 g/10 min. Multimodal MDPE can have an MFI of at least 0.1 g/10 min and maximum 1000 g/10 min. The preferred MFI values (e.g. for film production) are ranging between 0.4 g/10 min and maximum 8 g/10 min, or at least, equal to, or between any two of 0.4, 0.5, 0.6, 0.7, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.5, 2.75, 3.0, 4.0, 5.0, 6.0, 7.0 and 8.0 g/10 min.

[0081] The polypropylene can be selected from a propylene homopolymer, a random copolymer polypropylene, an impact copolymer, or any mixture thereof. With preference, the polypropylene is a propylene homopolymer. The polypropylene can be isotactic or syndiotactic; with preference, the polypropylene is isotactic.

[0082] Properties of monomodal and/or multimodal homopolymer of propylene characterized by a narrow molecular weight distribution can include MFI, melting temperature, and the like. The melting temperature and MFI can be any range or value. The MFI of the polypropylene can be at least 0.1 g/10 min, maximum 2000 g/10 min. The preferred MFI values (e.g., for film production) are ranging between 0.8 g/10 min and maximum 30 g/10 min, or at least, equal to, or between 0.8, 1 , 2, 3, 4, 5, 10, 15, 20, 25, 30 g/10 min. A melting point of the polypropylene can be at least 140 °C, or at least, equal to, or between any two of 140, 145, 150, 155, 160, and 170 °C. Isotactic polypropylene is polypropylene where the methyl groups are oriented on one side of the carbon backbone. This arrangement creates a greater degree of crystallinity and can result in a stiffer material that is more resistant to creep than both atactic polypropylene and polyethylene. Isotactic polypropylene can have a melting point from 140 to 170 °C, preferably 150-166 °C.

[0083] Properties of monomodal and/or multimodal random copolymer polypropylene characterized by a narrow molecular weight distribution can include MFI, melting temperature, and the like. The melting temperature and MFI can be any range or value. The MFI of the polypropylene can be at least 0.1 g/10 min, maximum 2000 g/10 min. The preferred MFI values (e.g., for film production) are ranging between 0.8 g/10 min and a maximum of 30 g/10 min, preferably a maximum of 20 g/10 min. A melting point of the random copolymer polypropylene can be at least 100 °C up to 160 °C, or at least, equal to, or between any two of 140, 145, 150, 155, and 160 °C. An isotactic random copolymer polypropylene can have a degree of isotacticity as determined by the content of mmmm pentads in the polymer. The content of mmmm pentads can be determined by ¹³ C NMR as described in U.S. Patent Application No. 20150031262. [0084] Impact copolymers, corresponding to a blend of homopolypropylene (or of a random copolymer of propylene and a few other olefins) with an elastomeric phase (like e.g., an ethylene- propylene rubber phase) can be used. The melting temperature of the impact copolymer is the same as one of the homopolypropylenes (or of a random copolymer of propylene and a few other olefins) or at least 100 °C up to 170 °C. The elastomeric phase content can be between 1 wt.% and 80 wt.%. Preferred values of the elastomeric content are ranging between 10 wt.% and 25 wt.%. The MFI of the impact copolymer can be at least 0.1 g/10 min, maximum 2000 g/10 min. The preferred MFI values (e.g., for film production) are ranging between 0.8 g/10 min and a maximum of 30 g/10 min, preferably a maximum of 20 g/10 min.

[0085] In some embodiments, the multilayered structure includes layers made from polyethylene characterized by a narrow molecular weight distribution and polypropylene characterized by a narrow molecular weight distribution. In some embodiments, the multilayered structure includes polyethylene layers made from a polyethylene characterized by a narrow molecular weight distribution (for example LLDPE) having a density of 0.910 g/cm ³ to 0.930 g/cm ³ and polypropylene layers made polypropylene characterized by a narrow molecular weight distribution. In one instance, the polyethylene of the polyethylene layer can have a density of 0.918 g/cm ³ . In some embodiments, the polyethylene of the polyethylene layer(s) can have an MFI of 3.0 to 4.0 g/10 min and the polypropylene of the polypropylene layer has an MFI 20 to 30 g/10 min. The polyethylene of the polyethylene layer(s) can have a melting temperature of about 100 °C to 120 °C, and the polypropylene layer can have a melting temperature of about 140 °C to 160 °C. In one instance, the polyethylene of the polyethylene layer can polyethylene layer has a melting temperature of 108.5 °C and the polypropylene of the polypropylene layer has a melting temperature of 151 °C. In some instance, the polyethylene of the polyethylene layer(s) can have a MWD from 2 to 4.5, or preferably 2 to 4. In some instance, the polypropylene of the polypropylene layer(s) can have a MWD from 2 to 4.5, or preferably 2 to 4. In some instance, the polyethylene of the polyethylene layer(s) and the polypropylene of the polypropylene layer(s) both have a MWD from 2 to 4.5, or more preferably 2 to 4.

[0086] In a preferred embodiment of the invention, the polypropylene and the polyethylene are selected to have crystallization temperature that the same or that show a difference of at most 15 °C; preferably at most 12°C, more preferably at most 10°C, even more preferably at most 8°C, most preferably at most 6°C. [0087] According to the invention, the polypropylene of the at least one polypropylene layer has a crystallization temperature that is equal to or higher than the crystallization temperature of the polyethylene of the at least one polyethylene layer; with preference the polypropylene of the at least one polypropylene layer has a crystallization temperature that is higher than the crystallization temperature of the polyethylene of the at least one polyethylene layer. In an embodiment, the polypropylene has a crystallization temperature that is higher than the crystallization temperature of the polyethylene of at least 0.1 °C and at most 15°C, preferably from 0.5 °C to 10°C, more preferably from 1 °C to 8°C.

[0088] In an embodiment, the polypropylene of the at least one polypropylene layer and polyethylene of the at least one polyethylene layer are selected in order to have the MFI of the polypropylene as determined according to ISO 1 133 at a temperature of 230 °C with a load of 2.16 kg being equal to or at most eight time higher than MFI of the polyethylene as determined according to ISO 1 133 at a temperature of 190 °C with a load of 2.16 kg; preferably the MFI of the polypropylene as determined according to ISO 1133 at a temperature of 230 °C with a load of 2.16 kg is at least two time and/or at most five time higher than MFI of the polyethylene as determined according to ISO 1133 at a temperature of 190 °C with a load of 2.16 kg. For example, if the polyethylene selected has an MFI of 3.5 g/10 min, the polypropylene selected may have an MFI ranging from 3.5 to 28 g/10 min.

[0089] In an embodiment, the multilayered polymeric structure comprises:

- from 40 to 60 wt.% of polyethylene based on the total weight of both the polyethylene and the polypropylene in the multilayered polymeric structure; and

- from 60 to 40 wt.% of polypropylene based on the total weight of both the polyethylene and the polypropylene in the multilayered polymeric structure.

[0090] Preferably, the multilayered polymeric structure comprises from, 42 to 58 wt.% of polyethylene based on the total weight of both the polyethylene and the polypropylene in the multilayered polymeric structure; more preferably from 45 to 55 wt.%; even more preferably, from 48 to 52 wt. %; and most preferably 50 wt.%.

[0091] Preferably, the multilayered polymeric structure comprises from, 58 to 42 wt.% of polypropylene based on the total weight of both the polyethylene and the polypropylene in the multilayered polymeric structure; more preferably from 55 to 45 wt.%; even more preferably, from 52 to 48 wt. %; and most preferably 50 wt.%. [0092]

2. Additives

[0093] The polymer structures and compositions of the present invention can further include at least one additive. Except, in some cases, for the crystallizing agent (which includes nucleating agent) or the clarifying agent, these additives are not impactful to the engineering properties of the multilayered structure. Non-limiting examples of additives include an antiblocking agent, an antistatic agent, an antioxidant, a neutralizing agent, a blowing agent, a dye, a flame retardant, a filler, an impact modifier, a mold release agent, an oil, another polymer, a pigment, a processing agent, a reinforcing agent, a crystalizing agent (which includes nucleating agent), a clarifying agent, a slip agent, a stabilizer, an UV resistance agent, and combinations thereof. Additives are available from various commercial suppliers. Non-limiting examples of commercial additive suppliers include BASF (Germany), Dover Chemical Corporation (U.S.A.), AkzoNobel (The Netherlands), Sigma-Aldrich® (U.S.A.), Atofina Chemicals, Inc., and the like. An overview of suitable additives may be found in Plastics Additives Handbook, ed. H. Zweifel, 5 ^th edition, 2001 , Hanser Publishers. The total amount of additives generally does not exceed 5 wt.% based on the weight of the polymer. a. Crystalizing agents

[0094] Non-limiting examples of crystalizing agents that can be used with the polymeric structures and compositions of the present invention include calcium carbonate (CaCOs), barium sulfate (BaS04), silica (S1O2), kaolin, talc, mica, titania (T1O2), alumina (AI2O3), a zeolite, mono-or polycarboxylic aromatic acid, a dye, a pigment, metal carboxylates, metal aromatic carboxylate, hexahydrophthalic acid metal salts, stearates, organic phosphates, bisamides, sorbitols, or a combination thereof. A non-limiting example of metal aromatic carboxylate includes sodium benzoate. The increase of the crystallization temperature of the polypropylene can be used as an illustration of the effect of the crystalizing agent efficiency. Such increase depends on the nature and content of crystalizing agent, but typical content values are ranging between 50 and 5000 ppm, more usually between 100 and 2000 ppm. b. Light stabilizers

[0095] The polymeric structures and compositions of the present invention can include a light stabilizer. In certain aspects, at least, equal to, or between any two of 0.01 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, and 1.0 wt.% of the light stabilizer can be included in the polymeric structure or composition of the present invention. The light stabilizer can be a hindered amine light stabilizer. The term“hindered amine light stabilizer” refers to a class of amine compounds having certain light stabilizing properties. Non-limiting examples, of hindered amine light stabilizers (HALS) include 1-cyclohexyloxy-2,2,6,6-tetramethyl- 4-octadecylaminopiperidine; bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate; bis(1-acetoxy-

2.2.6.6-tetramethylpiperidin-4-yl) sebacate; bis(1 ,2,2,6,6-pentamethylpiperidin-4-yl) sebacate; bis(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl) sebacate; bis(1-octyloxy-2, 2,6,6- tetramethylpiperidin-4-yl) sebacate; bis(1-acyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate; bis(1 ,2,2,6,6-pentamethyl-4-piperidyl) n-butyl-3,5-di-tert-butyl-4-hydroxybenzyl malonate; 2,4- bis[(1-cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl)butyl amino]-6-(2-hydroxyethyl amino-s- triazine; bis(1 -cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl) adipate; 2,4-bis[(1-cyclohexyloxy-

2.2.6.6-piperidin-4-yl)butylamino]-6-chloro-s-triazine; 1-(2-hydroxy-2-methylpropoxy)-4-hydroxy-

2.2.6.6-tetramethylpiperidine; 1-(2-hydroxy-2-methylpropoxy)-4-oxo-2, 2,6,6- tetramethylpiperidine; 1 -(2-hydroxy-2-methyl propoxy)-4-octadecanoyloxy-2,2,6,6-tetramethyl piperidine; bis(1-(2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperid in-4-yl) sebacate;bis(1- (2-hydroxy-2-methylpropoxy)-2,2,6,6-tetramethylpiperidin-4-y l) adipate; 2,4-bis{N-[1 -(2-hydroxy- 2-methyl propoxy)-2,2,6,6-tetramethylpiperidin-4-yl]-N-butylamino}-6- (2-hydroxyethylamino)-s- triazine; 4-benzoyl-2,2,6,6-tetramethylpiperidine; di-(1 ,2,2,6,6-pentamethylpiperidin-4-yl) p- methoxybenzylidenemalonate; 2,2,6,6-tetramethylpiperidin-4-yl octadecanoate; bis(1-octyloxy-

2.2.6.6-tetramethylpiperidyl) succinate; 1 ,2,2,6,6-pentamethyl-4-aminopiperidine; 2-undecyl-

7,7,9,9-tetramethyl-1 -oxa-3,8-diaza-4-oxo-spiro[4,5]decane; tris(2,2,6,6-tetramethyl-4-piperidyl) nitrilotriacetate; tris(2-hydroxy-3-(amino-(2,2,6,6-tetramethylpiperidin-4-yl)p ropyl) nitrilotriacetate; tetrakis(2,2,6,6-tetramethyl-4-piperidyl)-1 ,2,3,4-butane-tetracarboxylate; tetrakis(1 , 2, 2,6,6- pentamethyl-4-piperidyl)-1 ,2,3,4-butane-tetracarboxylate; 1 ,1 '-(1 ,2-ethanediyl)-bis(3, 3,5,5- tetramethylpiperazinone); 3-n-octyl-7,7,9,9-tetramethyl-1 ,3,8-triazaspiro[4.5]decan-2,4-dione; 8- acetyl-3-dodecyl-7,7,9,9-tetramethyl-1 ,3,8-triazaspiro[4.5]decane-2,4-dione; 3-dodecyl-1-

(2,2,6,6-tetramethyl-4-piperidyl)pyrrolidin-2,5-dione; 3-dodecyl-1-(1 , 2,2,6, 6-pentamethyl-4- piperidyl)pyrrolidine-2,5-dione; N,N'-bis-formyl-N,N'-bis(2,2,6,6-tetramethyl-4- piperidyl)hexamethylenediamine; reaction product of 2,4-bis[(1 -cyclohexyloxy-2,2,6,6-piperidin- 4-yl)butylamino]-6-chloro-s-triazine with N,N'-bis(3-aminopropyl)ethylenediamine);condensate of 1-(2-hydroxyethyl)-2,2,6,6-tetramethyl-4-hydroxypiperidine and succinic acid; condensate of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-hexamethylenediami ne and 4-tert-octylamino-2,6- dichloro-1 ,3,5-triazine; condensate of N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)- hexamethylenediamine and 4-cyclohexylamino-2,6-dichloro-1 ,3,5-triazine; condensate of N,N - bis-(2,2,6,6-tetramethyl-4-piperidyl)hexamethylenediamine and 4-morpholino-2,6-dichloro-1 ,3,5- triazine; condensate of N,N'-bis-(1 ,2,2,6,6-pentamethyl-4-piperidyl)hexamethylenediamine and 4- morpholino-2,6-dichloro-1 ,3,5-triazine; condensate of 2-chloro-4,6-bis(4-n-butylamino-2, 2,6,6- tetramethyl piperidyl)-1 ,3,5-triazine and 1 ,2-bis(3-aminopropylamino)ethane; condensate of 2- chloro-4,6-di-(4-n-butylamino-1 ,2,2,6,6-pentamethylpiperidyl)-1 ,3,5-triazine and 1 ,2-bis-(3- aminopropylamino)ethane; a reaction product of 7,7,9,9-tetramethyl-2-cycloundecyl-1-oxa-3,8- diaza-4-oxospiro[4,5]decane and epichlorohydrin; poly[methyl, (3-oxy-(2, 2,6,6- tetramethylpiperidin-4-yl)propyl)]siloxane, CAS#182635-99-0; reaction product of maleic acid anhydride-C18-C22-a-olefin-copolymer with 2,2,6,6-tetramethyl-4-aminopiperidine; oligomeric condensate of 4,4'-hexamethylenebis(amino-2,2,6,6-tetramethylpiperidine) and 2,4-dichloro-6- [(2,2,6,6-tetramethylpiperidin-4-yl)butylamino]-s-triazine end-capped with 2-chloro-4,6- bis(dibutylamino)-s-triazine; oligomeric condensate of 4,4'-hexamethylenebis(amino-1 ,2,2,6,6- pentaamethylpiperidine) and 2,4-dichloro-6-[(1 ,2,2,6,6-pentaamethylpiperidin-4-yl)butylamino]-s- triazine end-capped with 2-chloro-4,6-bis(dibutylamino)-s-triazine; oligomeric condensate of 4,4 - hexamethylenebis(amino-1-propoxy-2,2,6,6-tetramethyl piperidine) and 2,4-dichloro-6-[(1- propoxy-2,2,6,6-tetramethylpiperidin-4-yl)butylamino]-s-tria zine end-capped with 2-chloro-4,6- bis(dibutylamino)-s-triazine; oligomeric condensate of 4,4'-hexamethylenebis(amino-1-acyloxy- 2,2,6,6-tetramethyl piperidine) and 2,4-dichloro-6-[(1-acyloxy-2,2,6,6-tetramethylpiperidin-4- yl)butylamino]-s-triazine end-capped with 2-chloro-4,6-bis(dibutylamino)-s-triazine; and product obtained by reacting (a) with (b) where (a) is product obtained by reacting 1 ,2-bis(3- aminopropylamino)ethane with cyanuric chloride and (b) is (2,2,6,6-tetramethyl piperidin-4- yl)butylamine; poly[[6-[(1 ,1 ,3,3-tetramethylbutyl)amino]-1 ,3,5-triazine-2,4-diyl][(2,2,6,6- tetramethyl-4-piperidinyl)imino]-1 ,6-hexanediyl[(2,2,6,6-tetramethyl-4-piperidinyl)imino]]) (CAS Number: 71878-19-8); butanedioic acid, dimethylester, polymer with 4-hydroxy-2, 2,6,6- tetramethyl-1 -piperidine ethanol (CAS Number: 65447-77-0); Alkenes, C20-24 a-, polymers with maleic anhydride, reaction products with 2,2,6,6-tetramethyl-4-piperidinamine (CAS Number: 152261-33-1 ). Also included are the sterically hindered N-H, N-methyl, N-methoxy, N-hydroxy, N- propoxy, N-octyloxy, N-cyclohexyloxy, N-acyloxy and N-(2-hydroxy-2-methylpropoxy) analogues of any of the above mentioned compounds. Non-limiting examples of commercial light stabilizers are available from BASF under the trade name Uvinul® 4050H, 4077H, 4092H, 5062H, 5050H, 4092H, 4077H, 3026, 3027, 3028, 3029, 3033P, and 3034 or Tinuvin® 622. c. Antistatic agent [0096] The polymeric structures and compositions of the present invention can include an antistatic agent. Antistatic agents can be used to inhibit accumulation of dust on plastic articles. Antistatic agents can improve the electrical conductivity of the plastic compositions, and thus dissipate any surface charges, which develop during production and use. Thus, dust particles are less attracted to the surface of the plastic article, and dust accumulation is consequently reduced. In certain aspects of the present invention, the antistatic agent can be a glycerol monostearate, ethoxylated fatty acid amines ( e.g ., N,N-bis-(2-hydroxyethyl) coco fatty amine (CAS Number: 61791 -31-9)), diethanolamides (e.g., N,N-bis(2-hydroxyethyl)dodecanamide; CAS Number: 120- 40-1 )), or ethoxylated sorbitan esters (e.g., Octadecanoic acid 2-[2- hydroxyethyl)octadecylamino]ethyl ester; CAS Number: 52497-24-2), Non-limiting examples of commercial antistatic agents include Clariant’s Hostastat® FA 24, FA 38 and FA 68, AkzoNobel’s Armostat 2000, or Sabo’s Sabostat A 300.

[0097] A polymeric structure or composition of the present invention can include 0.01 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, and 1 wt.% of total anti-static agent based on the total with of the polymeric structure or composition. d. Lubricant

[0098] The polymeric structures and compositions of the present invention can include a lubricant. A lubricant can be added to a thermoplastic polymer to improve the mould-making characteristics. The lubricant can be a low molecular compound from a group of fatty acids, fatty acid esters, wax ester, fatty alcohol ester, amide waxes, metal carboxylate, montanic acids, montanic acid ester, or such high molecular compounds, as paraffins or polyethylene waxes. In certain aspects of the present invention, the lubricant is a metal stearate. Non-limiting examples of metal stearates include zinc stearate, calcium stearate, lithium stearate or a combination thereof, preferably calcium stearate. A polymeric structure or composition of the present invention can include at least, equal to, or between any two of 0.01 wt.%, 0.2 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, and 1 wt.% of total lubricant based on the total weight of the polymeric structure or composition. e. Antioxidant

[0099] The polymeric structures and compositions of the present invention can include an antioxidant. An antioxidant can provide protection against polymer degradation during processing. Phosphites are known thermal oxidative stabilizing agents for polymers and other organic materials. The antioxidant can be a phosphite-based antioxidant. In certain aspects phosphite- antioxidants include, but are not limited to, triphenyl phosphite, diphenylalkyl phosphites, phenyldialkyl phosphites, tris(nonylphenyl)phosphite, trilauryl phosphite, trioctadecyl phosphite, distearyl pentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl)phosphite, diisodecyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, tristearyl sorbitol triphosphite, tetrakis(2,4-di-tertbutylphenyl)-4,4'-biphenylene diphosphonite, bis(2,4- dicumylphenyl)pentaerythritol diphosphite, a phosphorous acid, triphenyl ester, polymer with a- hydro- >-hydroxypoly[oxy(methyl-1 ,2- ethanediyl)], C10-16 alkyl esters, 5,7-bis(1 ,1- dimethylethyl)-3-[2,3(or 3,4)-dimethylphenyl]-2(3H)-benzofuranone. A polymeric structure or composition of the present invention can include at least, equal to, or between any two of 0.01 wt.%, 02 wt.%, 0.3 wt.%, 0.4 wt.%, 0.5 wt.%, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%, and 0.1 wt.% of total antioxidant based on the total weight of the polymeric structure or composition. Non- limiting examples of commercially available antioxidants include Irgafox® 168, Irganox® 1010, and Irganox® HP-136 available from BASF, Doverphos S9228T and Doverphos® LGP-1 1 available from Dover Chemical Company, and Utranox® 626 phosphite, Hostanox® P-EP, and WESTON® 619F phosphite available from Addivant (U.S.A.).

B. Preparation of Multilayered Polymeric Materials

[00100] A variety of different techniques can be used to form the polyethylene and polypropylene, or the polyethylene and polypropylene compositions, into a multilayered structure. For example, suitable forming techniques may include, for instance, extrusion casting, flat sheet die extrusion, blown film extrusion, tubular trapped bubble film processes, etc.

[00101] The polyethylene and other optional additives can be melt blended together to form polyethylene composition. The polypropylene and other optional additives can be melt blended together to form a polypropylene composition. The polypropylene and polyethylene compositions can be masterbatches. Melt blending may occur at a temperature range of from 170 °C to 340 °C, 200 °C to 285 °C, or from 200 °C to 240 °C to form the polymer composition.

[00102] In some embodiments, the preparation of a multilayered polymeric structure of the present invention can include extruding a polyethylene characterized by a narrow molecular weight distribution or composition thereof and a polypropylene characterized by a narrow molecular weight distribution or composition thereof to form at least one polyethylene layer and at least one polypropylene layer that is in direct contact with at least a portion of the polyethylene layer such that an interface is formed between the polyethylene and polypropylene layers. The choice of the polymer can include determining the crystallization temperature (T _c ) of the polymers. Crystallization temperatures can be determined using differential scanning calorimetry. In some instances, the polypropylene can have a high crystallization temperature than the polyethylene. Crystallization temperatures can be increased by the addition of a nucleating agent ( e.g . addition of 100 to 2000 ppm of a nucleating agent). In a non-limiting example, the polypropylene characterized by a narrow molecular weight distribution can have a crystallization temperature of 100 to 125 °C (without nucleating agent, the crystallization temperature is often close to 105 °C) and the polyethylene characterized by a narrow molecular weight distribution can have a crystallization temperature of 90 °C to 125 °C. FIG. 1 depicts a schematic of a multilayer film packaging application that produces a multilayered structure of the present invention having alternating layers of polyethylene and polypropylene. In FIG. 1 , system 100 includes an extruder system 102 and multiplier system 104. Polypropylene composition 106 and polyethylene composition 108 can be fed to extruder system 102 and through multiplier system 104 to produce multilayered polymeric structure 1 10. Polyethylene composition 106 can include polyethylene separately or in combination with optional additives. Polypropylene composition 108 can include polypropylene separately or in combination with optional additives.

[00103] Extruders system 102 can include a co-extrusion system. As shown in FIG. 1 , polyethylene composition 106, and polypropylene composition 108 can be fed to polyethylene and polypropylene extruders 1 12 and 1 14, respectively. The extruders can be in fluid communication with a multiplier system 104. As an alternative, a co-extrusion system containing more than one polyethylene and one polypropylene can be used. Additional layers can be polyethylene and polypropylene, but other polymers, polar or apolar polymers can be used. Whatever the considered system, it is important that, in the final structure, at least one polyethylene layer and at least one polypropylene layer are in direct contact with at least a portion of the polyethylene layer such that an interface is formed between the polyethylene and polypropylene layers. In a preferred embodiment, structures containing only polyethylene and polypropylene, preferably nucleated polypropylene, are used in the multilayered structure.

[00104] Extruders 1 12 and 1 14 can each include one screw rotatably mounted and received within a barrel (e.g., cylindrical barrel). The extruders can be a single screw or twin screw extruder. For example, a single screw extruder can include a housing or barrel and a screw is rotatably driven on one end by a suitable drive (typically including a motor and gearbox). Twin-screw extruder that contains two separate screws can be employed. The configuration of the screw is not particularly critical to the present invention and it may contain any number and/or orientation of threads and channels as is known in the art. For example, the screw can include a thread that forms a generally helical channel radially extending around a core of the screw. A feed section and melt section can be defined along the length of the screw in each extruder. The feed section can be the input portion of the barrel where the polypropylene and optional additives or polyethylene and optional additives are added. The melt section is the phase change section in which the polymer can be changed from a solid to a liquid. While there is no precisely defined delineation of these sections when the extruder is manufactured, it is well within the ordinary skill of those in this art to reliably identify the feed section and the melt section in which phase change from solid to liquid can be occurring. Although not necessarily required, the extruder can have a mixing section that is located adjacent to the output end of the barrel and downstream from the melting section. If desired, one or more distributive and/or dispersive mixing elements can be employed within the mixing and/or melting sections of the extruder. As is well known in the art, the mixing may be further improved by using pins in the barrel that create a folding and reorientation of the polymer melt, such as those used in Buss Kneader extruders, Cavity Transfer mixers, and Vortex Intermeshing Pin mixers. The extruder can, in addition, have side feeder(s) allowing introduction e.g., of additives via masterbatches or introduction of a blowing agent.

[00105] Multiplier system 104 can include a multilayer feedblock and/or multiple interfacial surface generators capable of dividing two or more polymer melt streams into a plurality of layers each, interleave these layers, and merge the many layers of two or more polymers into a single multilayer stream. The layers from any given melt stream can be created by sequentially bleeding off part of the stream from a flow channel into side channel tubes that feed layer slots for the individual layers in the feedblock. The multiplication factor can be dependent upon the geometry of the multiplier system. For example, two extruders can be used to feed the two polymeric materials into a feedblock to make a structure that includes 20 layers. Assuming 3 multipliers can be attached to the outflow of the feedblock system and each multiplier doubles the number of layers fed in; the polymeric layered product can include 160 total horizontal layers. Many multiplier systems are known in the art and as well as methods to introduce layer thickness gradient by controlling layer flow and are dependent on the application. In conventional processes, layer flow can be controlled by choices made in machining the shape and physical dimensions of the individual side channel tubes and layer slots. While, the multilayer system 104, as described in FIG. 1 , contains a feedblock and/or multiple interfacial surface generators, the feedblock can be replaced by a multilayer die. As shown in FIG. 1 , the die is a flat die, but other die geometries such as a circular die e.g., for multilayer blown film production are contemplated. C. Multilayered Polymeric Structure and Uses Thereof

[00106] The multilayered polymeric structure can include alternating layers of polypropylene and polyethylene or alternating layers of polyethylene and polypropylene. In a non-limiting example, the multilayered polymeric structure 1 10 can have 2 to 10000 polyethylene layers and 2 to 10000 polypropylene layer, or 50 to 200 layers of polyethylene and 50 to 200 layers polypropylene or 60 to 180 layers of polyethylene and 60 to 180 layers of polypropylene, or 155 to 165 layers of polyethylene and 155 to 165 layers of polypropylene. In some embodiments, the multilayered polymeric structure can have a plurality of layers of at least, equal to, or between any two of, 10, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 850, 900, 950, 1000, 1100, 1200, 1500, 1800, 1900, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500, and 10000 polyethylene players and at least, equal to, or between any two of, 10, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 850, 900, 950, 1000, 1 100, 1200, 1500, 1800, 1900, 2000, 2500, 3000, 3500, 4000, 4500, 5000, 5500, 6000, 6500, 7000, 7500, 8000, 8500, 9000, 9500, and 10000 polypropylene layers. It should be understood that the number of layers is not fixed. Referring to FIG. 1 , in structure 1 10, polypropylene layer 1 16 is in direct contact with polyethylene layer 1 18 such that interface 120 is formed between layers. The multilayered polymeric structure can have any thickness.

[00107] In certain embodiments, the multilayered polymeric structure can have an actual oxygen permeability coefficient (P02) that is less than its predicted P02. Permeability values for the LLDPE having a narrow molecular weight distribution can be 0.25 to 0.35 (m*cm ^A 3)/(m ^A 2*24hrs*Pa), or about 0.3 (m*cm ^A 3)/(m ^A 2*24hrs*Pa). Permeability values for HDPE having a narrow molecular weight distribution can be 0.1 to 0.25 (m*cm ^A 3)/(m ^A 2*24hrs*Pa), or about 0.2 (m*cm ^A 3)/(m ^A 2*24hrs*Pa). Permeability values for iPP having a narrow molecular weight distribution can be 0.6 to 0.8 (m*cm ^A 3)/(m ^A 2*24hrs*Pa) or about 0.7

(m*cm ^A 3)/(m ^A 2*24hrs*Pa). Permeability values for MDPE are intermediate between these two cases. By way of example, a predicted P02 of a multilayered polymeric structure made from metallocene (single site catalyst) polyethylene P02 = 0.3 (mxcm ³ )/(m ² x24hrsxPa) and metallocene homopolymer polypropylene P02 = 0.07 (mxcm ³ )/(m ² x24hrsxPa) and the actual P02 of the multilayer device is 0.07 (mxcm ³ )/(m ² x24hrsxPa). Predicted P02 can be calculated for a film that includes polypropylene and polyethylene layers using equation (1 ): With Fr _E being a value, ranging between 0 and 1 and describing the volume content of polyethylene in the final device. The difference between P02 predicted and P02 actual can be determined by equation (2):

Without wishing to be bound by theory, it is believed that associated improved barrier properties are related to the stronger interface between the polypropylene and polyethylene. The stronger interface can be attributed to polypropylene crystallizing first ( e.g when a nucleating agent is introduced), a stronger interface is created as compared to a polypropylene without a nucleating agent or a polypropylene that crystallized at a temperature lower than the polyethylene. Notably, and as illustrated in the non-limiting examples an HDPE with a nucleated iPP had improved barrier properties as compared to other films made using non-nucleated iPP.

[00108] The multilayered polymeric structure of the present invention can have a melt strength greater than the melt strength of the individual polymers used to make the multilayered polymeric structure or multilayered polymer structures made using multi-site catalysts. The tear strength of the multilayered polymeric structures of the present invention can also be greater than what would be expected for the same global polymer but without the multilayer polymeric structure. Notably, and as illustrated in a non-limiting manner in the Examples, the multilayered polymeric structures made from polyethylene characterized by a narrow molecular weight distribution and polypropylene characterized by a narrow molecular weight distribution had observable strain hardening and a constant interfacial viscosity over time. Without wishing to be bound by theory, it is believed that the choice of single-site catalyzed polymers having a narrow molecular weight distribution provides a higher density of interfacial entanglements of the two polymers in the multilayered structure of the present invention.

[00109] In some embodiments and as illustrated in the non-limiting Examples, the multilayered polymeric structure includes 160 layers of alternating low-density polyethylene layers and homopolymer polypropylene layers, where the polyethylene and polypropylene layers are both produced using a metallocene catalyst. Such a structure can have an engineering strain of at least 700% at 35 MPa and a tear strength of at least 130 Nmnr ¹ and less than predicted P02 properties. [00110] Due to its unique properties, the multilayer polymeric structure of the present can be used as a stand-alone product or incorporated into other types of products. For example, the multilayer structure can be used in a stand-alone form as a shrink film, cling film, stretch film, sealing film, sheet, foamed sheets etc., or to form a package. In some instances, the film can also be laminated to one or more substrates to form a composite. The substrate(s) can include a film, a fibrous layer (e.g., nonwoven web, paper web, woven fabric, knit fabric, etc.), a foam layer, a metal layer (e.g., foils), and so forth. In some embodiments, the film can be a standalone hygienic film, an oxygen barrier film for food packaging, a foamed layered sheet, or the like.

EXAMPLES

[00111] The present invention will be described in greater detail by way of specific examples. The following examples are offered for illustrative purposes only and are not intended to limit the invention in any manner. Those of skill in the art will readily recognize a variety of noncritical parameters which can be changed or modified to yield essentially the same results.

Testing Methods

[00112] Engineering strain was determined by cutting samples into dogbone geometries (22 mm x 4.8 mm ^c 0.6 mm). The dogbone specimens were uniaxially elongated in the extrusion direction at a testing speed of 5 mm/min (Shimadzu AGS-X, 500 N load cell) and the stress vs. strain response was recorded in accordance with ASTM D638 standard.

[00113] “Density” is defined as weight per volume. Density can be determined by ISO 1 183.

[00114] MFI values can be determined according to ISO 1 133 at a temperature of 230 °C for polypropylene and 190 °C for polyethylene with a load of 2.16 kg. A person skilled in the art can select a temperature for determining the MFI of the polymer without any difficulty.

[00115] Elongation (or extensional) measurements were conducted at 180 °C using the ARES Elongational Viscosity Fixture (EVF). The protocol for the measurement comprises:

Oven heating with elongational fixture including clamps for at least 20 minutes.

Sample: for this analysis, the sample is a 160-layer structure obtained by coextrusion of polyethylene and PP. The polyethylene and the polypropylene layers are each 3-5 pm thick. The loading of the sample in the EVF equipment may take up to ten seconds, and the time how fast one can load determines the reheating time.

Oven reheating, up to 5 minutes, and thermal equilibration of the sample.

Elongational measurements on rectangular plates at 180 °C: in this step the strain rate is constant and the torque response is measured and plotted as elongational viscosity. The duration of this step depends on the strain rate and the maximum Hencky strain to be achieved with.

[00116] All elongational tests were conducted in ARES EVF at 180 °C under nitrogen environment. A constant strain rate was applied to measure the torque signal which is later interpreted as elongational viscosity.

[00117] Tear strength was determined by Trouser tear testing (ASTM D624, type T). Each multilayered sheet was cut to a width of 15 mm and a length of 150 mm. A single 40 mm length cut was made down the centerline of the sample width (7.5 mm from each edge). Each leg of the tear sample was placed in a Shimadzu AGS-X, 500 N load cell tensile testing apparatus. In accordance with the cited ASTM standard, the sample was torn at a rate of 50 mm/min and a force vs. displacement curve was recorded. The tear strength is defined as the plateau tearing force normalized by sample thickness.

[00118] Oxygen barrier properties were determined by ASTM D3985 with the following conditions:

- A 4inx 4in square is cut out of the center of the test specimen using a premade stencil that includes three holes for the screws used to ensure a tight seal on the testing apparatus. Each specimen is inspected for flaws or blemishes on the film surface that could affect testing. Each sample is handled with gloves to prevent oils from the hands from altering the surface of the specimen. When applicable, the inside of the film (i.e. a polypropylene outside layer) is labeled and placed faced down to be in contact with the carrier gas.

- The average thickness of each specimen is measured using a micrometer and reported in microns. Five spots are measure on the film (the four edges of the square and the center) and the average is used. When two specimens from the same sample film are being tested at the same time, the average from both specimens is used as the thickness value. - The atmospheric pressure is measure and reported in mBar. A barometer is placed on top of the instrument, and the reading is entered at the start of each test cycle. Typical readings are between 1005 and 1015 mBar.

- The carrier gas used for instrument is Ultra High Purity Nitrogen. The pressure of the gas as it enters the instrument is 25 psi. This value is the pressure for the instrument recommended by the vendor, and is verified by a pressure gauge placed on the line right before it enters the instrument.

- The flow rate of the nitrogen carrier gas is 10 + 0.1 cc/min.

- All test specimens are allowed to condition at 23°C ± 2°C in the lab prior to testing.

- The temperature of the test specimen is measured by the instrument throughout the testing process and the average is reported at the end. The temperature is typically measured to be between 22 and 23°C and is reported to the nearest 0.1 °C.

- The values of permeance and permeability are not reported. The O2TR value is reported in cc/(m ^2* day) in ambient air (20.9% O2). The O2TR value is captured every 30 minutes, and the average value is reported at the end of testing. Any results reported need to be multiplied by a correction factor of 4.78 to report the values at 100% O2 _.

- The apparatus used is the Model 8200 Oxygen Permeation Analyzer by Systech Illinois.

The instrument utilizes a very sensitive coulometric sensor, the Coulox detector, for the measurement of low concentrations of oxygen.

For calibration, a certified calibration film purchased from Systech Illinois every year was used. The known value of the film is entered, and then the calibration film is loaded into one chamber for testing. After the O2TR has stabilized, the instrument is calibrated. The current calibration film has an O2TR value of 61.9 cc/(m ^2* day) at 100% oxygen.

- The effective area for permeation on specimen tested is 50cm ² . For samples with an area less than 50cm ² , a mask is used. The specific area of the masked sample is measured and recorded.

[00119] Prior to testing, a 60 minutes purge time is observed. Once testing has begun, the test is run for an extended period of time to allow for stabilization of the O2TR. For most samples, the test time is 24 hours or until the collected values are within 1 % for low permeable samples and 0.1 % for highly permeable samples. Atomic force microscopy (AFM; Nanoscope III with Multimode system, Digital Instruments, Santa Barbara, CA, USA) was determined using the following procedure and equipment: Films were cut perpendicular to the extrusion direction to image edge-on using the same cryo-ultramicrotome at -120 °C with a series of progressive cuts. Initial cutting was carried out at a step length of 1 pm and a glass knife velocity of 6 mm/sec. Each cutting step reduced the step length and knife velocity until a final setting of 50 nm step length and 1 mm/sec velocity were reached. A series of finishing cuts were also made at 50 nm step length and 1 mm/sec velocity with a Diatome diamond knife. The microtome process ensured a smooth imaging surface for AFM in tapping mode. Samples were examined in the repulsive regime using a silicon tip (resonant frequency = 166 kHz, spring constant = 2 N/m, and radius = 8 nm).

[00120] DSC measurements: Melting temperatures T _meit and crystallization temperatures T _cryst were determined according to ISO 3146 on a DSC Q2000 instrument by TA Instruments (USA). To erase the thermal history, the samples (between 1 and 10 mg of the multilayer device introduced in a DSC cell) were first heated from 20 C to 220 °C at 10 °C/min and kept at 220 °C for a period of 3 minutes. The sample is later cooled at -10 °C/min, from 220 °C to 20 °C, kept at 20 °C during 3 minutes, and later heated again from 20 °C to 220 °C at 10 °C/min. When reported, the melting temperature corresponds to the value obtained during the second heating process.

[00121] Molecular weights are determined by Size Exclusion Chromatography (SEC) at high temperature (145 °C). A 10 mg polyethylene or polypropylene sample is dissolved at 160 °C in 10 mL of trichlorobenzene (technical grade) for 1 hour. Analytical conditions for the GPC-IR from Polymer Char are:

Injection volume: +/- 0.4 mL;

Automatic sample preparation and injector temperature: 160 °C;

Column temperature: 145 °C;

Detector temperature: 160 °C;

Column set: 2 Shodex AT-806MS and 1 Styragel HT6E;

Flow rate: 1 mL/min;

Detector: IR5 Infrared detector (2800-3000 cm-1 );

Calibration: Narrow standards of polystyrene (commercially available);

Calculation for polyethylene: Based on Mark-Houwink relation (log-io(MPE) = 0.965909 log10(MPS) - 0,28264); cut off on the low molecular weight end at M _PE = 1000.

[00122] Calculation for polypropylene: Based on Mark-Houwink relation (log-io(Mpp) = log-io(Mps) - 0.25323 ); cut off on the low molecular weight end at M _PP = 1000. [00123] The molecular weight averages used in establishing molecular weight/property relationships are the number average (M _n ), weight average (M _w ) and z average (M _z ) molecular weight. These averages are defined by the following expressions and are determined to form the calculated M,:

Ni and W, are the number and weight, respectively, of molecules having molecular weight Mi. The third representation in each case (farthest right) defines how one obtains these averages from SEC chromatograms h, is the height (from baseline) of the SEC curve at the i _th elution fraction and M, is the molecular weight of species eluting at this increment. The molecular weight distribution (MWD) is then calculated as Mw/Mn.

[00124] Layer counting: The co-extruded multilayer PE/PP samples were cryo-microtomed at -120°C with a glass knife in order to expose a smooth edge-on cross-section of the multilayer film. Each sample was cryo-microtomed at an angle so that the knife marks were clearlydistinguishable from the multilayer structure. The trimmed PE/PP multilayer cross-section was exposed to the vapors of ruthenium tetroxide (Ru0 ₄ ) solution in a 10 mL vial for 30 min beforebeing dried in a fume hood overnight. Additional trimming was performed by cryo-microtome at -120°Cwith a glass knife in order to remove excess Ru0 ₄ aggregate on the surface. Following the second trimming, 1.5 nm of iridium was sputter coated (Leica EM ACE600) on the cryo-microtomed surface to prevent charging during SEM (Hitachi SU8230) imaging. The SEM instrument was equipped with a cold field emission gun and the SEM images were obtained with an accelerating voltage of 25 kV. Due to the different staining rates between PE and PP by Ru0 ₄ , the PE/PP multilayer structure was observed with a back-scattered electron detector (BSE) where PE and PP layers are distinguished and bright and dark domain, respectively. To span the entire sample at the resolution needed to measure layer thicknesses with sub-microns dimensions, 6 to 9 separate high magnification micrographs were manually stitched together. Individual layer thicknesses were measured using Image J and the total number of individual layers (N) was counted.

[00125] Materials. Polymers were obtained from ExxonMobil Chemical and TOTAL Petrochemicals and are listed in Table 1 and Table 2

Table 1

Table 2

Example 1

(Characterization of Multilayered polyethylene and polypropylene Structure and

Comparative Samples)

[00126] Multilayered structures having 160 layers were prepared using a coextrusion device as follows. In brief, one stream of polyethylene was spaced to form 10 alternating layers alternating with 10 individual streams of isotactic polypropylene (iPP) to produce a 20 layer flow. The flow was then passed through 3 layer multiplication devices. Each layer multiplication device doubled the number of layers in the flow so that the final film would contain 160 layers. After layer multiplication, the flow passed through an exit die with a final temperature of 180 °C. The overall volumetric flow rate was kept constant at 32 cm ³ /min. Melt contact time was calculated based upon the continuity equation. With die dimensions, 50 mm ^c 1.2 mm and volumetric flow rate ~32 cm ³ /min, the average linear flow velocity was calculated to be 8.9 mm/sec. The die land length was measured to be 63 mm, giving an approximate melt interfacial contact time in the die of 7 sec. After leaving the exit die, 160 layer films were quenched on counter-rotating chill rolls with a gap of 0.8 mm between the cooled steel rolls. A gap between the exit die lip and rolls required ~2.8 sec before quenching, giving a total melt interfacial contact time of ~10 sec. The final dimensions of the extrudate after quenching were 22 mm ^c 0.8 mm. The gear pump metering iPP flow displaced 1.6 cm ³ /rotation, while the gear pump metering the polyethylene flow displaced 0.8 cm ³ /rotation. The pump RPM were set to give 16 cm ³ /min for each stream. These 50:50 (PE vol:iPP vol) films were fabricated from mhE-miP, mIE-miP (multilayer structures of the present invention), and zhE-ziP (comparative examples) with gear pumps speeds of 20 RPM for polyethylene and 10 RPM for iPP.

[00127] FIGS. 2A-2C show images of the multilayered structures for a comparative zhE/ziP multilayered structure made from multisite catalyzed polypropylene and multisite catalyzed PE, a mhE/miP multilayer structure of the present invention and a mIE/miP multilayer of the present invention made from polymers having a narrow molecular weight distribution. FIG. 3 shows DSC scans for the multilayered structures. The top scan is mIE/miP, the middle scan is mhE/miP, and the bottom scan is zhE/ziP. Table 3 lists the degree of crystallinity of the polymers in each of the multilayered polymeric structure and the controls (individual polyethylene and iPP materials used in each of the respective multilayer films). FIGS. 4A-4C shows the extensional viscosity for the individual polymers and the multilayered structures of the present invention (FIGS. 4A and 4B) and comparative samples (FIG. 4C) using polypropylene and the various types of polyethylene listed in Table 1. FIGS. 5A-5D show the mechanical properties of the individual polymers and the multilayered structures. FIGS. 6A and 6B show the O2 barrier properties of the multilayered structures of the present invention and the comparative multilayered structure. From the data, it was determined that the multilayered samples of the present invention had better mechanical and melt strength, than the comparative multilayered samples made from multisite catalyzed polypropylene and multisite catalyzed PE. The barrier properties, as determined through permeability properties, for the mIE/miP samples of the present invention were better than the comparative multilayered structure.

Table 3

Example 2

(Dripping test)

[00128] A dripping test as shown on figure 7 was conducted under the same conditions for four different films. In this test a flame was approached to a sample of a film arranged vertically until said film takes fire. The fire propagation rate and the time to the first drip were measured and reported in below table 4.

Table 4

[00129] Film 1 was a single layer film produced from mIE. Film 2 was a single layer film produced from miP. Film 3 was a mIE/miP film with 640 layers. Film 4 was a mIE/miP film with 2560 layers. Both films 3 and 4 comprised 50 wt.% of mIE and 50 wt.% of miP. All the films had the same thickness.

[00130] Surprisingly, an improvement in the anti-dripping properties is shown for the films comprising the multilayered polymeric structure according to the invention by comparison to the films produced from pure polyethylene or pure polyethylene. This improvement in the anti-dripping properties is obtained without the addition of any anti-dripping additive.

Although embodiments of the present application and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the embodiments as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the above disclosure, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein can be utilized. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.