Improving bend radius and storage length in polyethylene structures

Abstract

An article comprising an expanded polyethylene substrate (12) having a longitudinal length, a first zone (14) and a second zone (16), wherein the first zone has a first density and the second zone has a second density, the second density being greater than the first density, and the second zone is embossed.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of Provisional Application No. 63 / 433,093, filed December 16, 2022, which is incorporated herein by reference in its entirety for all purposes.

[0002] Field FIELD OF THE DISCLOSURE The present disclosure relates generally to an apparatus, system, and method for embossing expanded polyethylene, and more particularly, to an apparatus, system, and method for embossing expanded polyethylene usable for medical devices. [Background technology]

[0003] background The method used to process a material is important because it can impart certain properties to the processed material. Certain properties may be necessary for the processed material to function for its intended purpose or may allow the processed material to be used in new ways. The choice of processing method is important in a variety of industries, including, but not limited to, the medical device industry, particularly implantable medical devices. However, processed materials are used in a variety of industries, and properties desirable in one industry may also be important in another.

[0004] Medical devices are often required to be adaptable to suit the needs of a patient. For example, implantable devices made from engineered materials may be required to conform to or be adaptable to serpentine shapes. In adapting to serpentine geometries, the implantable device can be molded or engineered into various shapes. However, engineered materials can be subjected to stresses during engineering, making them susceptible to failure. What is needed are materials useful for providing medical devices that can operate without failure during an implantation procedure. Summary of the Invention

[0005] Abstract The present disclosure relates to methods for densifying expanded (expanded, expanded, stretched, or foamed) polyethylene, and articles produced thereby. For example, such methods and articles produced thereby include selectively densifying portions of an expanded polyethylene substrate to form a storage length, which can provide desirable characteristics such as increased bend radius, kink resistance, and durability.

[0006] According to one example ("Example 1"), an article includes an expanded polyethylene substrate having a longitudinal length, having a first zone and a second zone, the first zone having a first density, the second zone having a second density, the second density being greater than the first density, and the second zone being embossed.

[0007] According to another example ("Example 2"), further to Example 1, the expanded polyethylene substrate is compressed in at least one of the longitudinal or transverse directions to define a storage length along at least a portion of the longitudinal length.

[0008] According to another example ("Example 3"), in addition to Example 1, the expanded polyethylene substrate is a tubular member.

[0009] According to another example ("Example 4"), in addition to Example 3, the second zone is a ring extending around the tubular member at a longitudinal position defined along the longitudinal length.

[0010] According to another example ("Example 5"), further to Example 4, the second zone includes a plurality of rings extending around the circumference of the tubular member at a plurality of longitudinal positions defined along the longitudinal length.

[0011] According to another example ("Example 6"), in addition to Example 1, the expanded polyethylene substrate does not contain an adhesive.

[0012] According to another example ("Example 7"), further to Example 1, the expanded polyethylene substrate includes multiple expanded polyethylene layers bonded together.

[0013] According to one example ("Example 8"), a method of forming an article optionally includes providing an expanded polyethylene substrate having a first density; and selectively densifying a portion of the expanded polyethylene substrate to form one or more densified portions of the expanded polyethylene substrate, wherein the expanded polyethylene substrate has one or more non-densified portions having a first density, the one or more densified portions having a second density higher than the first density, and the one or more densified portions are disposed adjacent to the one or more non-densified portions.

[0014] According to another example ("Example 9"), in addition to Example 8, the method further includes forming the expanded polyethylene substrate into a tubular member.

[0015] According to another example ("Example 10"), further to Example 9, selectively densifying a portion of the expanded polyethylene substrate includes applying heat to an exterior surface of the expanded polyethylene substrate.

[0016] According to another example ("Example 11"), in addition to example 9, the method further includes placing the tubular member over a mandrel.

[0017] According to another example ("Example 12"), further to Example 11, selectively densifying a portion of the expanded polyethylene substrate includes applying heat to an interior surface of the expanded polyethylene substrate.

[0018] According to another example ("Example 13"), in addition to Example 12, selectively densifying a portion of the expanded polyethylene substrate includes selectively heating a portion of the mandrel.

[0019] According to another example ("Example 14"), further to Example 8, selectively densifying a portion of the expanded polyethylene substrate includes applying ultrasonic energy to an exterior surface of the expanded polyethylene substrate.

[0020] According to another example ("Example 15"), further to Example 8, selectively densifying a portion of the expanded polyethylene substrate includes applying ultrasonic energy to an interior surface of the expanded polyethylene substrate.

[0021] According to one example ("Example 16"), a method of forming an article optionally includes providing an expanded polyethylene substrate having a first density; compressing the expanded polyethylene substrate in a longitudinally and / or transversely compressed state, wherein the expanded polyethylene substrate has a first density; selectively densifying a portion of the expanded polyethylene substrate while in the longitudinally and / or transversely compressed state to form a densified portion of the expanded polyethylene substrate, wherein the densified portion has a second density greater than the first density; and releasing the expanded polyethylene substrate from the longitudinally and / or transversely compressed state.

[0022] According to another example ("Example 17"), in addition to example 16, the method further includes forming the expanded polyethylene substrate into a tubular member.

[0023] According to another example ("Example 18"), in addition to Example 17, selectively densifying a portion of the expanded polyethylene substrate includes applying heat to an exterior surface of the expanded polyethylene substrate.

[0024] According to another example ("Example 19"), in addition to example 17, the method further includes placing the tubular member over a mandrel.

[0025] According to another example ("Example 20"), further to example 19, selectively densifying a portion of the expanded polyethylene substrate includes applying heat to an interior surface of the expanded polyethylene substrate.

[0026] According to another example ("Example 21"), further to Example 20, selectively densifying a portion of the expanded polyethylene substrate includes selectively heating a portion of the mandrel.

[0027] According to another example ("Example 22"), further to Example 16, selectively densifying a portion of the expanded polyethylene substrate includes contacting the portion of the expanded polyethylene substrate with an element at about 110°C to about 180°C.

[0028] According to another example ("Example 23"), further to Example 16, selectively densifying a portion of the expanded polyethylene substrate includes applying ultrasonic energy to an exterior surface of the expanded polyethylene substrate.

[0029] According to another example ("Example 24"), further to example 16, selectively densifying a portion of the expanded polyethylene substrate includes applying ultrasonic energy to an interior surface of the expanded polyethylene substrate.

[0030] The foregoing examples are exemplary only and should not be construed as limiting or narrowing the scope of the inventive concepts otherwise provided by this disclosure. While multiple embodiments are disclosed, still other embodiments will become apparent to those skilled in the art from the following detailed description, which shows and describes illustrative examples. Accordingly, the drawings and detailed description are to be regarded as illustrative in nature and not restrictive. [Brief explanation of the drawings]

[0031] BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification, illustrating embodiments and, together with the description, serving to explain the principles of the disclosure.

[0032] [Figure 1] FIG. 1 is an embossed expanded polyethylene article according to some embodiments.

[0033] [Figure 2] FIG. 2 is an embossed expanded polyethylene article showing the inner and outer surfaces according to some embodiments.

[0034] [Figure 3] FIG. 3 is an embossed expanded polyethylene article shown in a bent configuration, according to some embodiments.

[0035] [Figure 4] FIG. 4 is a method for making an embossed expanded polyethylene article according to some embodiments.

[0036] [Figure 5] FIG. 5 is an embossed expanded polyethylene article produced by the method of FIG. 4, according to some embodiments.

[0037] [Figure 6] FIG. 6 is a method for making an expanded polyethylene embossed article having a storage length according to some embodiments.

[0038] [Figure 7] FIG. 7 is an embossed expanded polyethylene article produced by the method of FIG. 6, according to some embodiments. DETAILED DESCRIPTION OF THE INVENTION

[0039] Detailed Description Definitions and Terminology The present disclosure is not intended to be construed in a limiting sense. For example, the terms used in this application should be interpreted broadly in relation to the meaning that one of ordinary skill in the art would assign to such terms.

[0040] With respect to terms related to imprecision, the terms "about" and "approximately" may be used interchangeably to refer to measurements that include the stated measurement and measurements that are reasonably close to the stated measurement. A measurement that is reasonably close to the stated measurement deviates from the stated measurement by a reasonably small amount, to the extent that it would be understood and readily grasped by one of ordinary skill in the relevant art. Such deviations may result from, for example, measurement error, differences in the calibration of measuring and / or manufacturing equipment, human error in reading and / or setting measurements, fine-tuning made to optimize performance and / or structural parameters to account for variations in measurements associated with other components, specific implementation scenarios, imprecise adjustment and / or manipulation of objects by humans or machines, and / or the like. When it is determined that the value of such reasonably small deviations would not be readily grasped by one of ordinary skill in the relevant art, the terms "about" and "approximately" are understood to mean plus or minus 10% of the stated value.

[0041] The term "laminate," as used herein, refers to multiple layers of films, composites, or other materials, such as, but not limited to, polymers, such as, but not limited to, elastomers, elastomeric or non-elastomeric materials, and combinations thereof.

[0042] The term "film," as used herein, refers generically to one or more of a membrane, a composite, or a laminate.

[0043] The term "polyethylene" (PE), as used herein, includes all types of polyethylene, including but not limited to expanded polyethylene (ePE).

[0044] The term "selective densification," as used herein, generally refers to densification at predetermined locations on a substrate and includes various degrees of densification, including partial densification, where the substrate maintains a porous, open microstructure after densification, and complete densification, where the substrate has a closed microstructure. Selective densification can include, but is not limited to, densification throughout the thickness of the substrate or along the length of the substrate, with adjacent areas remaining non-densified.

[0045] Description of Various Embodiments Those skilled in the art will readily appreciate that the various aspects of the present disclosure may be implemented by any number of methods and apparatus configured to perform the intended functions. It should also be noted that the accompanying drawings referred to herein are not necessarily drawn to scale and may be exaggerated to illustrate various aspects of the present disclosure, and in that regard, the drawings should not be construed as limiting.

[0046] The device shown in FIG. 1 is provided as an example of various features of the device, and while combinations of the illustrated features are clearly within the scope of the present invention, this example and its illustration are not intended to suggest that the inventive concepts provided herein are limited to fewer features, additional features, or alternative features to one or more of the features shown in FIG. 1.

[0047] The articles and methods can implement various forms of expanded polyethylene, including, but not limited to, membranes, films, tapes, tubes, etc. It is further understood that expanded polyethylene can have a variety of properties, including different thicknesses, fibril and node structures, porosity, density, etc. Thus, the embodiments discussed herein are not limited to any particular initial condition or form, but are understood to broadly encompass any expanded polyethylene starting material suitable for the described methods.

[0048] Referring to FIG. 1 , article 10 is shown, comprising an expanded polyethylene substrate 12 having a first zone 14 and a second zone 16. First zone 14 has a first density, and second zone 16 has a second density. The second density of second zone 16 is greater than the first density of first zone 14. Additionally, second zone 16 is embossed. Article 10 can be provided in a variety of configurations, including but not limited to those shown. Article 10 can be provided in a variety of three-dimensional shapes, such as a tubular member or tubular shape as shown in FIG. 1 . Article 10 can also be formed as a two-dimensional shape, such as a sheet. Sheets formed from article 10 can be provided in a variety of shapes, such as circular, rectangular, or other geometric shapes. It is understood that any of these two-dimensional shapes can be fabricated to provide a three-dimensional shape. For example, article 10 can be formed by bonding (e.g., gluing, joining, fusing, etc.) a sheet to itself, for example, to form a tubular member. By providing article 10 in a variety of shapes, article 10 can be endowed with particular properties that are unique to each shape or that are consistent regardless of the shape of article 10.

[0049] In one embodiment, as shown in FIG. 1 , article 10 is formed as a tubular member 100. Tubular member 100 includes first and second zones 14, 16 that function to enhance durability, including abrasion resistance, when subjected to repeated bending operations, including in applications where compliance and durability are important factors. Additionally, tubular member 100 exhibits kink resistance, bend radius, compliance, and shelf life. While these features are specifically described with respect to tubular member 100, it will be understood that article 10 provided in other forms may also include these and similar features.

[0050] With further reference to FIG. 1 , the tubular member 100 includes first and second zones 14, 16, with the second zone 16 being a ring 102, which is a densified region, disposed (e.g., extending) along the circumference of the tubular member 100. The tubular member 100 can include multiple rings 102, which are densified regions of the tubular member 100, with each ring 102 spaced apart from adjacent rings 102 along the longitudinal length of the tubular member 100. Other geometric shapes of densified regions besides circumferential rings are also contemplated. For example, the densified region can be formed in a spiral pattern along the longitudinal length of the tubular member. The longitudinal length can be aligned with the longitudinal axis of the tubular member 110. The rings 102, which provide the densified regions, provide radial support to the tubular member 100 and act to resist radial forces and collapse due to either external forces (e.g., mechanical contact, pressure gradients, etc.) or internal forces (e.g., pressure gradients). The ring 102 can be disposed on the tubular member 100 such that the outer surface 104 is concave and the inner surface 106 is constant (e.g., smooth), as shown, for example, in FIG. 2 . Having a smooth inner surface 106 provides a lumen 108 (see FIG. 2 ) through which fluid can flow without disrupting fluid dynamics. Providing a concavity in the outer surface 104 can improve fixation of the tubular member 100 within the patient's lumen. It will be appreciated that the concavities in the ring 102 may instead be positioned such that the inner surface 106 is concaved while the outer surface 104 is smooth. In another alternative embodiment, the concavities formed by the ring 102 may be present on both the inner and outer surfaces 104, 106 (e.g., alternating, zoned, etc.).

[0051] Article 10 can be provided in a variety of configurations. In some embodiments, article 10 includes multiple polymer layers. For example, article 10 can be formed as a laminate of expanded polyethylene layers. These layers can be bonded together via adhesives, bonding processes, or mechanical processes. In some embodiments, article 10 is formed into a particular configuration, such as the tubular member 100 described above. Article 10 can be substantially adhesive-free. In these embodiments, the configuration is formed by joining one portion of article 10 to another portion of article 10, or article 10 can be provided in the shape of a configuration (e.g., extrusion molding, etc.).

[0052] Referring to FIG. 3 , an embodiment of a tubular member 100 is shown. The tubular member 100 includes a plurality of rings 102 (e.g., second zone 16 embossed to form a densified portion of the article 10). The tubular member 100 is shown in a bent configuration 160 in which the tubular member 100 resists kinking. The rings 102 on the tubular member 100 allow the tubular member 100 to achieve a small bend radius without kinking, thereby maintaining an open lumen 108 and facilitating fluid flow through the lumen 108 without occlusion or disruption of fluid dynamics. Because the tubular member 100 is not kinked, the tubular member 100 is more durable, as kinks are often weak points in implantable devices over time. This is especially true when the implantable device is placed within a patient's dynamic lumen, which experiences changes in shape, orientation, position, etc.

[0053] 4, a method 400 of forming an expanded polyethylene article is provided, according to some embodiments. The manufacturing method can include the steps of providing an expanded polyethylene substrate 410, selectively densifying a portion of the expanded polyethylene substrate 420, and optionally forming the expanded polyethylene substrate into an expanded polyethylene article 430.

[0054] 4, in providing 410 an expanded polyethylene substrate, the polyethylene substrate has a first density. The expanded polyethylene substrate may include, but is not limited to, a film, a membrane, a laminate, etc. Providing 410 an expanded polyethylene substrate may further include disposing the expanded polyethylene substrate on a surface (e.g., surface 202 of FIG. 5). The surface may include a mandrel.

[0055] Further to FIG. 4 , when a portion of the expanded polyethylene substrate 420 is selectively densified, a densified portion of the expanded polyethylene substrate (e.g., second zone 16 of tubular member 100 of FIG. 1 ) is formed. Selective densification refers to densifying a portion of the expanded polyethylene substrate 420 to increase the density of the portion of the expanded polyethylene substrate 420. In some embodiments, selective densification includes increasing the density while maintaining porosity in the selectively densified portion of the expanded polyethylene substrate 420 (e.g., not fully densifying so that an open microstructure is maintained). In some embodiments, selective densification includes increasing the density without maintaining porosity (e.g., fully densifying so that an open microstructure is absent). The portion of the expanded polyethylene substrate 420 that is not selectively densified is a porous portion that defines a non-densified portion. Selective densification can occur through the thickness of the expanded polyethylene substrate 420 or along the length of the expanded polyethylene substrate 420. The densified portion of the expanded polyethylene substrate 420 is not densified throughout the entire thickness of the expanded polyethylene substrate 420, thereby maintaining at least some porosity throughout the thickness of the expanded polyethylene substrate 420. In some embodiments, the non-densified portion of the expanded polyethylene substrate 420 can be selectively masked to remain undensified and porous. The densified portion of the expanded polyethylene substrate can include a second density, which can be higher than the first density. The densified portion of the expanded polyethylene substrate can be disposed adjacent to a portion of the expanded polyethylene substrate having the first density. Selectively densifying 420 a portion of the expanded polyethylene substrate can be performed by embossing. Selectively densifying 420 a portion of the expanded polyethylene substrate can further include applying heat to an outer surface of the expanded polyethylene substrate (e.g., the outer surface 104 of the tubular member 100 in FIGS. 1 and 2). Selectively densifying 420 a portion of the expanded polyethylene substrate can further include applying heat to an inner surface of the expanded polyethylene substrate (e.g., the inner surface 106 of the tubular member 100 in FIG. 2).Applying heat to the expanded polyethylene substrate can further include placing the expanded polyethylene substrate on a mandrel and selectively heating a portion of the mandrel (eg, surface 202 in FIG. 5).

[0056] 4, the method 400 can optionally further include forming 430 the expanded polyethylene substrate into an expanded polyethylene article. The expanded polyethylene article can include a tubular member. Forming the expanded polyethylene into a tubular member can further include placing the tubular member over a mandrel. In some embodiments, the expanded polyethylene article can be formed by joining one portion of the article to another portion of the article, or the article can be provided in the shape of a structure (e.g., extrusion, etc.).

[0057] FIG. 5 illustrates an embossed expanded polyethylene article 220 produced by the method of FIG. 4 , according to some embodiments. FIG. 5 includes providing an expanded polyethylene substrate 200 (e.g., a film, membrane, laminate, etc.). The expanded polyethylene substrate 200 can be a tubular member (e.g., the tubular member 100 of FIG. 1 ). The expanded polyethylene substrate 200 can have an outer surface 206 and an inner surface 208 (e.g., a lumen). The expanded polyethylene substrate 200 can be disposed on a surface 202 (e.g., a mandrel) for further processing of the expanded polyethylene substrate 200. When disposed on the surface 202, the expanded polyethylene substrate 200 has a first density. The first density can be substantially uniform throughout the expanded polyethylene substrate 200, or only a portion of the expanded polyethylene substrate 200 can have the first density. Once the expanded polyethylene substrate 200 is provided, the expanded polyethylene substrate 200 can be disposed on the surface 202 and selectively densified. Selective densification can include embossing. Embossing can be performed via an external device (not shown, e.g., a soldering iron, a heated stamp, ultrasonic bonding, etc.), or embossing can be performed via surface 202 (e.g., a mandrel can be heated, etc.). Embossing via an external device can selectively densify exterior surface 206 and / or interior surface 208. Embossing via surface 202 can selectively densify interior surface 208.

[0058] In some embodiments, embossing or selective densification of the polyethylene substrate 200 can be performed using ultrasonic energy. Ultrasonic energy can be applied to the outer surface 206 and / or the inner surface 208 of the polyethylene substrate 200 (e.g., using a mandrel). Ultrasonic energy can be applied using a rotary ultrasonic bonding unit including a horn and anvil assembly. The anvil can include a pattern (e.g., a circumferential ring) that can be embossed onto the polyethylene substrate 200. The use of ultrasonic energy can result in a more pronounced difference in density and porosity between the embossed and non-embossed portions of the polyethylene substrate 200. This can be because the non-embossed portions are less susceptible to ultrasonic energy than heating. This can better maintain the density and porosity of the non-embossed portions.

[0059] Embossing the expanded polyethylene substrate 200 densifies the embossed portions, resulting in a second density that is higher than the first density. The embossing can be performed in multiple steps, such that the expanded polyethylene substrate 200 has both embossed portions 210 and non-embossed portions 212. The embossing can be performed throughout the expanded polyethylene substrate 200 to create an embossed article 220. It is also understood that when the expanded polyethylene substrate 200 is embossed, the embossing configuration (e.g., pattern) may shorten the length of the expanded polyethylene substrate 200. For example, FIG. 4 illustrates an expanded polyethylene substrate 200 provided as an expanded polyethylene tubular member 230 that has been embossed to include a circumferential ring 204 on its outer surface 206. When the circumferential ring 204 is embossed into the outer surface 206 of the expanded polyethylene tubular member 230, the longitudinal length of the expanded polyethylene tubular member is shortened. A longitudinal length may be defined along the longitudinal axis L of the expanded polyethylene tubular member. The expanded polyethylene substrate 200 is provided with a first longitudinal length L1. When the embossed portion 210 is formed in a portion of the expanded polyethylene substrate 200, the expanded polyethylene substrate 200 has an intermediate longitudinal length L1. The intermediate longitudinal length L1 is shorter than the first longitudinal length L1. When the embossed portion 210 is formed over the entire length of the expanded polyethylene substrate 200 to create the embossed tubular article 220, the embossed tubular article 220 has a second longitudinal length L2. The second length L2 is shorter than the intermediate length L1. In some embodiments, the change in length between the first longitudinal length L1 and the second longitudinal length L2 is small.

[0060] It is also understood that the densification or embossing process may or may not densify the expanded polyethylene substrate 200 throughout the entire thickness of the embossed portion 210 of the expanded polyethylene substrate 200. For example, the expanded polyethylene substrate 200 may be densified only in a portion of its thickness, resulting in a portion of the thickness that is not embossed (e.g., the inner surface 208 of the expanded polyethylene tubular member 230). The portion of the thickness that is not embossed may substantially retain a first density (e.g., the inner surface 208). Thus, when a cross-section of the expanded polyethylene substrate 200 is viewed with the densified portion located on the outer surface 206, the density in the embossed portion 210 comprises a continuum of density throughout the entire thickness of the expanded polyethylene substrate 200 in the embossed portion 210. Thus, by substantially retaining the first density, the inner surface 208 may substantially retain its porosity, fluid dynamics, and / or hemodynamics.

[0061] Embossing or selective densification of expanded polyethylene substrate 200 can be accomplished by heating expanded polyethylene substrate 200 with a tool to about the melting temperature of expanded polyethylene substrate 200, or from about 110°C to about 180°C. For example, expanded polyethylene substrate 200 can be selectively heated to temperatures of from about 110°C to about 120°C, from about 120°C to about 130°C, from about 130°C to about 140°C, from about 140°C to about 150°C, from about 150°C to about 160°C, from about 160°C to about 170°C, and from about 170°C to about 180°C.

[0062] 6, a method 600 of forming an expanded polyethylene article is provided, according to some embodiments. The manufacturing method may include method steps including providing an expanded polyethylene substrate 610, compressing the expanded polyethylene substrate into a compressed state 620, selectively densifying a portion of the expanded polyethylene substrate 630, releasing the expanded polyethylene substrate from a compressed state 640, and optionally forming the expanded polyethylene substrate into an expanded polyethylene article 650.

[0063] With further reference to FIG. 6, in providing 610 an expanded polyethylene substrate, the expanded polyethylene substrate has a first density. The expanded polyethylene substrate can include, but is not limited to, a film, a membrane, a laminate, etc. The expanded polyethylene substrate can include a tubular member (e.g., expanded polyethylene tubular member 300 of FIG. 7). Providing 610 an expanded polyethylene substrate can further include disposing the expanded polyethylene substrate on a surface. The surface can include a mandrel (e.g., mandrel 302 of FIG. 7).

[0064] Further to FIG. 6, compressing the expanded polyethylene substrate into a compressed state 620 can be performed longitudinally and / or transversely such that the expanded polyethylene substrate is in a longitudinally and / or transversely compressed state.

[0065] Further to FIG. 6 , selectively densifying 630 a portion of the expanded polyethylene substrate can be performed while the expanded polyethylene substrate is in a longitudinally and / or transversely compressed state to form a densified portion of the expanded polyethylene substrate (e.g., densified portion 306 in FIG. 7 ). The densified portion can have a second density, which can be greater than the first density. The densified portion of the expanded polyethylene substrate can be disposed adjacent to a non-densified portion of the expanded polyethylene substrate having a first density (e.g., non-densified portion 308 in FIG. 7 ). Selectively densifying 630 a portion of the expanded polyethylene substrate can be performed by embossing. Selectively densifying 630 a portion of the expanded polyethylene substrate can further include applying heat to an outer surface of the expanded polyethylene substrate (e.g., outer surface 312 in FIG. 7 ). Selectively densifying 630 a portion of the expanded polyethylene substrate can further include applying heat 630 to an inner surface of the expanded polyethylene substrate (e.g., inner surface 314 in FIG. 7 ). Applying 630 heat to the expanded polyethylene substrate may further include placing the expanded polyethylene substrate on a mandrel and selectively heating a portion of the mandrel.

[0066] Further to FIG. 6 , releasing 640 the expanded polyethylene substrate from a compressed state can include releasing the expanded polyethylene substrate from a longitudinally and / or transversely compressed state. Method 600 can optionally further include forming 650 the expanded polyethylene substrate into an expanded polyethylene article. The expanded polyethylene article can include a tubular member. Forming the expanded polyethylene into a tubular member can further include placing the tubular member over a mandrel.

[0067] Additionally, FIG. 7 illustrates an expanded polyethylene embossed article 10 manufactured by the method of FIG. 6 , according to some embodiments. In some embodiments, the embossed article 320 can be provided to have a storage length. This can be achieved by a method for manufacturing the article 10. The method for manufacturing the article can be substantially similar to the method illustrated in FIG. 6 . For example, the method includes providing an expanded polyethylene substrate, such as a tubular member 300 having a first density, where the tubular member 300 is disposed on a surface 302 (e.g., a mandrel 302). The expanded polyethylene substrate is not limited to the tubular member 300 and can include, but is not limited to, a flat member or other geometric shapes. The expanded polyethylene substrate can be provided in an original length X1. The tubular member 300 includes an outer surface 312 and an inner surface 314 (e.g., a lumen). Once disposed, the tubular member 300 is compressed along a longitudinal or transverse direction to a compressed state 304 (e.g., uncompressed through the thickness of the tubular member 300). In this embodiment, the compressed state 304 is defined longitudinally and by the longitudinal axis L of the tubular member 300. The compressed state 304 can have a compressed length XC that is shorter than the original length X1. While the tubular member 300 is held in the compressed state 304 (e.g., while the tubular member 300 is held in the longitudinally compressed state 304), the tubular member 300 is selectively densified to form a densified portion 306. The densified portion 306 can be adjacent to a non-densified portion 308. The densified portion 306 of the tubular member 300 comprises a second density that is higher than the first density of the tubular member 300 prior to densification. The selective densification can be achieved by embossing. Similar to the above description, the embossing process may or may not densify the tubular member 300 throughout the entire thickness of the tubular member 300 at the densified portion 306. For example, the tubular member 300 may be densified over only a portion of the tubular member 300 (e.g., the outer surface 312 of the tubular member 300) and not over a portion of the thickness of the tubular member 300 (e.g., the inner surface 314 of the tubular member 300).The unembossed portion of the thickness of the tubular member can substantially maintain the first density (e.g., on the inner surface of the tubular member 300). Thus, when a densified portion is disposed on the outer surface 312 of the tubular member 300, when the tubular member 300 is viewed in cross section, the density in the densified portion 306 is a continuum of density throughout the thickness of the tubular member 300 at the densified portion 306. Thus, the inner surface of the tubular member can substantially maintain its porosity, fluid dynamics, and / or hemodynamics. The tubular member 300 can be embossed or densified with various patterns, including, but not limited to, rings 310, thereby creating a densified tubular member 320.

[0068] After the tubular member 300 is selectively densified, the tubular member 300 is released from the compressed state 304 in which it was maintained during the densification process. As shown in FIG. 7 , the tubular member 300 is released from the compressed state 304. When the tubular member 300 is released from the compressed state 304, the densified tubular member 320 does not return to the tubular member's original length X1. In some embodiments, the shortened length (or width) X2 of the densified tubular member 320 can be the result of the tubular member 300 being embossed in the compressed state 304. Additionally, the shortened length (or width) X2 can be the result of either the embossing or the densification process. In either case, the tubular member 300 is embossed in the compressed state 304 to facilitate storage length within the expanded polyethylene substrate. Applying force to both ends of the densified tubular member 320 can expand the densified tubular member 320 and release the storage length to form the expanded densified tubular member 330. The expanded densified tubular member 330 has an expanded length (or width) X3. The expanded length (or width) X3 can include the entire storage length or a portion of the storage length. In embodiments where the entire storage length is included in the expanded length (or width) X3, the expanded length (or width) X3 can be substantially the same as the original length X1. In other embodiments, the expanded length (or width) X3 can be less than the original length X1.

[0069] In some embodiments, the expanded polyethylene substrate is not provided as tubular member 300, but instead is processed into a tubular member. This can occur before or after the embossing / densification process described herein. For example, the expanded polyethylene substrate can be formed into a tubular member and then placed on a mandrel and densified, similar to the densification process shown in FIG. 7. The expanded polyethylene substrate can be formed into a tubular substrate using any suitable method, including extrusion, bonding, gluing, bonding, etc. In other embodiments, the expanded polyethylene substrate is embossed / densified prior to forming the tubular member, for example, by bonding, gluing, or otherwise joining the ends of the embossed expanded polyethylene substrate together.

[0070] In some embodiments, embossing / densifying the expanded polyethylene substrate includes selectively applying heat to the outer surface of the expanded polyethylene substrate. In some embodiments, densification can occur at a temperature above the melting temperature of the expanded polyethylene substrate. In other embodiments, if an adhesive is present, densification can occur at the melting temperature of the adhesive. In some embodiments, the expanded polyethylene substrate is tubular member 300. Heat can be applied via a heating element such as a soldering iron, heat press, or heated tool. Heat is applied to the outer surface (e.g., outer surface 312 of tubular member 300) in a manner that maintains the structural properties of the inner surface (e.g., inner surface 314 of tubular member 300). Maintaining the inner surface of the expanded polyethylene substrate can maintain properties and functionality. For example, the outer surface can have a densified ring (e.g., ring 310) (e.g., formed by the densification process) for structural support, while the inner surface sufficiently retains selected structural properties, such as for hemodynamics, cell adhesion, texture, etc. It is understood that the reverse configuration is also possible, where the inner surface is modified by densification while the outer surface is an expanded polyethylene substrate that can fully retain selected structural or other properties. In other embodiments, modifying both the inner and outer surfaces can facilitate achieving specific characteristics of the embossed article 320 defined by the inner or outer surface or expanded polyethylene substrate (e.g., greater resistance to radial crush, increased shelf life, improved bend radius, etc.). Heat can be applied to the expanded polyethylene substrate near the melting temperature of the expanded polyethylene substrate, or by factors of about 110°C to about 180°C. For example, the expanded polyethylene substrate can be selectively heated to temperatures of about 110°C to about 120°C, about 120°C to about 130°C, about 130°C to about 140°C, about 140°C to about 150°C, about 150°C to about 160°C, about 160°C to about 170°C, and about 170°C to about 180°C. In some embodiments where the expanded polyethylene substrate is formed into a tubular member 300 prior to embossing / densification, the tubular member is placed on a mandrel 302 .While the tubular member is on the mandrel 302, the mandrel 302 may be selectively heated (e.g., in selected areas including strips, patterns, etc.) to facilitate embossing / densifying the inner surface of the tubular member 300.

[0071] While various materials may be implemented in accordance with the present disclosure, in one embodiment shown in FIG. 3, a multi-layer expanded polyethylene substrate is provided that is adhesive-free and has an open, breathable structure. The multi-layer expanded polyethylene substrate is wrapped around a cigarette to form a tubular member (e.g., tubular member 100). The multi-layer expanded polyethylene substrate is then selectively densified by localized heating (e.g., with a soldering iron) at about 110°C to about 180°C (e.g., about 175°C). As shown in FIG. 3, the selectively densified multi-layer expanded polyethylene substrate allows the tubular member 100 to exhibit high flexural strength without kinking.

[0072] Referring to FIG. 5, in one non-limiting embodiment, a six-layer, cigarette-wrapped, open, breathable expanded polyethylene substrate (e.g., provided as expanded polyethylene substrate 200) can be provided. The multilayer expanded polyethylene substrate is selectively heated to densify portions of the multilayer expanded polyethylene substrate into densified rings (e.g., circumferential ring 204). The multilayer expanded polyethylene substrate is selectively heated to about 110°C to about 180°C (e.g., about 150°C) using a soldering iron. The densified rings are spaced about 2 mm apart from one another along the longitudinal length of the multilayer expanded polyethylene substrate. The multilayer expanded polyethylene substrate can be provided in a length of about 9 cm before heating (e.g., constructed on a mandrel at a first length L1), and is compressed (i.e., densified) by selective heating to a length of about 7 cm (e.g., a second length L2) before being removed from the mandrel to form a densified ring.

[0073] Referring to FIG. 7 , in one non-limiting embodiment, a six-layer, cigarette-wrapped, open, breathable expanded polyethylene substrate is provided (e.g., provided as tubular member 300) and placed on a mandrel (e.g., surface 302). The multilayer expanded polyethylene substrate has a length of 9 cm (e.g., original length X1). The multilayer expanded polyethylene substrate is contracted to a length of 5.5 cm. The multilayer expanded polyethylene substrate is selectively heated to densify a portion of the multilayer expanded polyethylene substrate into a densified ring (e.g., contracted length XC). The multilayer expanded polyethylene substrate is selectively heated to a temperature range of about 110° C. to about 180° C. using a soldering iron. The multilayer expanded polyethylene substrate is then removed from the mandrel. When the multilayer expanded polyethylene substrate is relaxed, the length of the multilayer expanded polyethylene substrate is about 6 cm (e.g., contracted length X2). The multilayer expanded polyethylene substrate has a storage length that allows the multilayer expanded polyethylene substrate to extend to a length greater than 6 cm (e.g., expanded length X3). In some embodiments, the expanded polyethylene substrate is capable of recovering to a length of more than 6 cm before or after stretching.

[0074] While specific embodiments are shown herein, it is understood that different configurations and material properties can be selected and manipulated within the scope of the present disclosure. Additionally, specific embodiments provide for temperature, process, and property variations within the scope of the present disclosure.

[0075] The invention of this application has been described above both generally and with reference to specific embodiments. It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments without departing from the scope of the present disclosure. Therefore, it is intended that the embodiments cover the modifications and variations of the present invention provided they come within the scope of the appended claims and their equivalents.

Claims

1. 1. An article comprising an expanded polyethylene substrate having a longitudinal length, a first zone and a second zone, wherein the first zone has a first density and the second zone has a second density, the second density being greater than the first density, and the second zone is embossed.

2. The article of claim 1 , wherein the expanded polyethylene substrate is compressed longitudinally and / or transversely to define a storage length along at least a portion of the longitudinal length.

3. The article of claim 1 , wherein the expanded polyethylene substrate is a tubular member.

4. 4. The article of claim 3, wherein the second zone is a ring extending around the tubular member at a longitudinal position defined along the longitudinal length.

5. The article of claim 4 , wherein the second zone comprises a plurality of rings extending around the tubular member at a plurality of longitudinal positions defined along the longitudinal length.

6. The article of claim 1 , wherein the expanded polyethylene substrate is adhesive-free.

7. The article of claim 1 , wherein the expanded polyethylene substrate comprises a plurality of expanded polyethylene layers bonded together.

8. 1. A method of forming an article, comprising:

1. A method comprising selectively densifying a portion of an expanded polyethylene substrate to form one or more densified portions of the expanded polyethylene substrate, wherein the expanded polyethylene substrate has one or more non-densified portions having a first density, the one or more densified portions having a second density greater than the first density, and the one or more densified portions are disposed adjacent to the one or more non-densified portions.

9. The method of claim 8 further comprising forming the expanded polyethylene substrate into a tubular member.

10. The method of claim 9 , wherein selectively densifying a portion of the expanded polyethylene substrate comprises applying heat to an exterior surface of the expanded polyethylene substrate.

11. The method of claim 9 further comprising placing the tubular member over a mandrel.

12. The method of claim 11 , wherein selectively densifying a portion of the expanded polyethylene substrate comprises applying heat to an interior surface of the expanded polyethylene substrate.

13. The method of claim 12 , wherein selectively densifying a portion of the expanded polyethylene substrate comprises selectively heating a portion of the mandrel.

14. The method of claim 8 , wherein selectively densifying a portion of the expanded polyethylene substrate comprises applying ultrasonic energy to an exterior surface of the expanded polyethylene substrate.

15. The method of claim 8 , wherein selectively densifying a portion of the expanded polyethylene substrate comprises applying ultrasonic energy to an interior surface of the expanded polyethylene substrate.

16. 1. A method of forming an article, comprising: compressing the expanded polyethylene substrate in the longitudinal and / or transverse directions such that the expanded polyethylene substrate is in a longitudinally and / or transversely compressed state, wherein the expanded polyethylene substrate has a first density; selectively densifying a portion of the expanded polyethylene substrate while in the longitudinally and / or transversely compressed state to form a densified portion of the expanded polyethylene substrate, wherein the densified portion has a second density greater than the first density; and Releasing the expanded polyethylene substrate from the longitudinal and / or transverse compression; A method comprising:

17. The method of claim 16, further comprising forming the expanded polyethylene substrate into a tubular member.

18. The method of claim 17 , wherein selectively densifying a portion of the expanded polyethylene substrate comprises applying heat to an exterior surface of the expanded polyethylene substrate.

19. The method of claim 17 further comprising placing the tubular member over a mandrel.

20. 20. The method of claim 19, wherein selectively densifying a portion of the expanded polyethylene substrate comprises applying heat to an interior surface of the expanded polyethylene substrate.

21. The method of claim 20, wherein selectively densifying a portion of the expanded polyethylene substrate comprises selectively heating a portion of the mandrel.

22. 17. The method of claim 16, wherein selectively densifying a portion of the expanded polyethylene substrate comprises contacting the portion of the expanded polyethylene substrate with an element at about 110°C to about 180°C.

23. The method of claim 16, wherein selectively densifying a portion of the expanded polyethylene substrate comprises applying ultrasonic energy to an exterior surface of the expanded polyethylene substrate.

24. The method of claim 16, wherein selectively densifying a portion of the expanded polyethylene substrate comprises applying ultrasonic energy to an interior surface of the expanded polyethylene substrate.

Images