Forming monolithic polyethylene articles

Abstract

A method of forming a polyethylene (PE) article comprising: optionally providing a first support; assembling a plurality of polyethylene substrates on the first support, the plurality of polyethylene substrates defining a PE structure; applying a second support to the PE structure such that the PE structure is located between the first support and the second support; positioning the first support, the PE structure, and the second support in a position proximate the housing; and applying a force to the first support, the second support, and the PE structure such that the first support, the second support, and the PE structure expand to fit / conform to the shape of the housing wherein the housing limits expansion of the first support, the second support, and the PE structure beyond the housing such that the PE article is formed when the PE structure expands.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority of U.S. Provisional Application No. 63 / 433,132, filed on December 16, 2022, which is hereby incorporated by reference in its entirety for all purposes. Technical Field

[0003] The present disclosure generally relates to equipment, systems, and methods for processing polyethylene. More specifically, the present disclosure relates to equipment, systems, and methods for processing polyethylene that can be used in medical devices. Background Art

[0004] Material selection is crucial for providing functional articles. For example, implantable medical devices are typically formed from specific materials that are biocompatible and provide certain functions (such as cell adhesion, etc.).

[0005] Not only is material selection important, but the method used to process the material can also impart or provide specific properties, structures, or functions to the processed material, thereby facilitating the function of the article formed from the material. The specific properties imparted during the processing may be a prerequisite for the processed material to be suitable for a specific function. The choice of processing method is important in various industries, including but not limited to the medical device industry, and more specifically, for implantable medical devices. However, the processed material may be used in various industries, and the same properties required in one industry may also be important in other industries.

[0006] After many materials are formed into sheets, they are coupled and processed, ultimately forming a specific structure. However, these coupling points or seams are often weak points in the finished product or may cause other undesirable properties, such as particle accumulation, etc.

[0007] We need a material that can be reliably formed without these undesirable properties. Summary of the Invention

[0008] The present disclosure relates to a method, article, and apparatus produced by such a method for forming an integral expanded polyethylene (ePE) article from a polyethylene (PE) structure. For example, producing an article and apparatus by such a method includes applying a force to a PE structure to form a PE article. The PE article can be formed as integral and seamless. The PE article can also exhibit a series of desirable properties, such as durability, abrasion resistance, a smaller profile, high strength, and thromboresistance.

[0009] According to one example ("Example 1"), a method for forming a polyethylene (PE) product includes: optionally, providing a first support member; assembling a plurality of polyethylene substrates on the first support member, the plurality of polyethylene substrates defining a PE structure; applying a second support member to the PE structure so that the PE structure is located between the first support member and the second support member; positioning the first support member, the PE structure, and the second support member at a position close to a shell; and applying force to the first support member, the second support member, and the PE structure so that the first support member, the second support member, and the PE structure expand to fit the shell / conform to the shape of the shell, wherein the shell limits the expansion of the first support member, the second support member, and the PE structure beyond the shell so that the PE product is formed when the PE structure expands.

[0010] According to another example further to Example 1 ("Example 2"), a monolithic PE article was formed by applying a force to a PE structure.

[0011] According to another example further to Example 1 ("Example 3"), the monolithic PE article is seamless.

[0012] According to yet another further example of Example 1 ("Example 4"), the method further includes positioning the first support, the second support, and the PE structure around the mandrel.

[0013] According to yet another example further to Example 3 ("Example 5"), the mandrel is porous or perforated.

[0014] According to another example further to Example 1 ("Example 6"), the first support member and the second support member are formed of silicone.

[0015] According to another further example of Example 1 ("Example 7"), assembling the multiple polyethylene components also includes assembling other components formed by materials other than PE, and the materials other than PE include at least one of expanded polyethylene (ePE), polytetrafluoroethylene (PTFE) or expanded polytetrafluoroethylene (ePTFE).

[0016] According to another further example of Example 1 ("Example 8"), the method also includes heating the PE structure.

[0017] According to another further example of Example 1 ("Example 9"), applying force to the first support member, the second support member and the PE structure includes heating the liquid in the mandrel to about 130 degrees Celsius so that the liquid phase is converted into a gas, and the force is applied by the gas.

[0018] In a further example ("Example 10") according to Example 8, the liquid is heated into a gas, resulting in an expansion ratio of the liquid to the gas of approximately 1:1600.

[0019] According to another example further to Example 1 (“Example 11”), applying a force to the first support, the second support, and the PE structure includes releasing compressed gas.

[0020] According to one example (“Example 12”), a method of forming an integral polyethylene (PE) article includes: positioning a PE structure such that a first portion of the PE structure overlaps a second portion of the PE structure; applying heat to the PE structure; and expanding the PE structure while applying heat to the PE structure.

[0021] According to another example further to Example 12 (“Example 13”), positioning the PE structure includes positioning the PE structure between a first silicone support and a second silicone support.

[0022] According to another example further to Example 13 (“Example 14”), expanding the PE structure includes applying a force to one of the first silicone support and the second silicone support such that the first silicone support, the PE structure, and the second silicone support expand together.

[0023] According to another example further to Example 14 (“Example 15”), expanding the PE structure includes applying a force by pressure.

[0024] According to another example further to Example 15 (“Example 16”), the pressure is provided by heating a liquid to convert it into a gas.

[0025] According to another example further to Example 15 (“Example 17”), the pressure is provided by compressed gas.

[0026] According to another example further to Example 14 (“Example 18”), expanding the PE structure while applying heat forms a seamless integral PE article.

[0027] According to one example (“Example 19”), a method of forming a polyethylene (PE) article includes: assembling a PE structure onto a first forming support; placing a punch near the PE structure; applying a force to the PE structure through the punch such that the punch contacts the PE structure and pushes the PE structure into the first forming support; the PE structure conforming to the shape of the first forming support; applying heat to the PE structure; and releasing the punch from the PE structure to form a PE article that retains the shape of the first forming support.

[0028] According to another example further to Example 19 (“Example 20”), applying heat to the PE structure includes heating to about 130 degrees Celsius.

[0029] Another example, further to Example 19 (“Example 21”), involves applying heat to a PE structure to densify a PE article, with the density varying in a gradient across the entire PE article.

[0030] Another example, further to Example 19 (“Example 22”), involves applying force to a punch and heat to a PE structure simultaneously.

[0031] Another example, further to Example 19 (“Example 23”), involves applying heat to a PE structure while the PE structure is within a first forming support.

[0032] The foregoing examples are merely examples and should not be construed as limiting or otherwise narrowing the scope of any inventive concept provided by this disclosure. Although multiple examples are disclosed, other embodiments will be apparent to those skilled in the art from the following detailed description that shows and describes illustrative examples. Accordingly, the drawings and detailed description are considered to be illustrative in nature and not restrictive. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The accompanying drawings are used to assist in further understanding the present disclosure, which are incorporated into and form a part of the specification. The drawings show embodiments of the present disclosure and, together with the specification, are used to explain the principles of the present disclosure.

[0034] Figure 1 is a block diagram of a method for forming a polyethylene (PE) article from multiple polyethylene substrates according to some embodiments;

[0035] Figure 2 is an illustration of an embodiment for forming a PE article from a PE structure according to some embodiments;

[0036] Figure 3 is according to some embodiments, Figure 2 a side view illustration of an embodiment;

[0037] Figure 4 is a block diagram of a method for forming a monolithic PE article according to some embodiments;

[0038] Figure 5 is an illustration of an embodiment for forming a monolithic PE article according to some embodiments;

[0039] Figure 6 is a block diagram of a method for forming a PE article using a forming support according to some embodiments;

[0040] Figure 7 is a side view illustration of an embodiment for forming a polyethylene PE article using a forming support according to some embodiments;

[0041] Figure 8A and 8B show the microstructure of the PE article of Example 1 processed at a temperature above the melting temperature;

[0042] Figure 9 shows the thickness data of the PE articles of Example 1 and Example 2;

[0043] Figure 10 The bubble point data of the PE articles of Example 1 and Example 2 are shown;

[0044] Figure 11 The air leakage data of the PE articles of Example 1 and Example 2 are shown;

[0045] Figure 12 The peel data of the PE article of Example 2 are shown. Detailed Description

[0046] Definitions and Terms

[0047] The present disclosure is not intended to be read in a limiting manner. For example, the terms used in this application should be read broadly in the context of the meaning ascribed to these terms in the art.

[0048] For imprecise terms, the terms "about" and "approximately" may be used interchangeably and mean that a measured value includes the measured value and also includes any measured value reasonably close to the measured value. As understood and readily determined by one of ordinary skill in the relevant art, there is a reasonably small deviation between the measured value reasonably close to the measured value and the measured value. For example, such deviations may be attributable to measurement errors, differences in calibration of measurement and / or manufacturing equipment, human error in reading and / or setting measurements, fine-tuning due to measurement differences associated with other components to optimize performance and / or structural parameters, particular implementation scenarios, imprecise adjustment and / or manipulation of objects by a person or a machine, etc. If it is determined that one of ordinary skill in the relevant art cannot readily determine the value of such a reasonably small difference, the terms "about" and "approximately" may be understood to mean plus or minus 10% of the stated value.

[0049] The term "laminate" as used herein refers to a multi-layer film, composite material, or other material, such as but not limited to polymers (such as but not limited to elastomers, elastomeric materials, or non-elastomeric materials and combinations thereof).

[0050] The term "film" as used herein generally refers to one or more of a film, composite material, or laminate.

[0051] The term "biocompatible material" as used herein generally refers to any material having biocompatible properties, including synthetic materials (such as but not limited to biocompatible polymers) or biomaterials (such as but not limited to bovine pericardium). Biocompatible materials can include the first film and the second film as described herein for various embodiments.

[0052] The term "polyethylene" (PE) as used herein includes all types of polyethylene, including but not limited to expanded polyethylene (ePE).

[0053] Description of Various Embodiments

[0054] Those skilled in the art will understand that various aspects of the present disclosure can be implemented by any number of methods and devices configured to perform the desired functions. It should also be noted that the accompanying drawings referred to herein are not necessarily drawn to scale and may be enlarged to illustrate various aspects of the present disclosure. In this regard, the drawings should not be considered limiting.

[0055] The present disclosure relates to integral articles and devices, and methods of forming such articles and devices. The integral articles and devices can be formed from a starting material comprising multiple layers that are processed to form an integral single article, where each of the multiple layers is indistinguishable from one another. The integral articles and devices can include articles and devices in which the starting material layers are integrated (e.g., meshed) with one another. In some embodiments, the integral article can be formed to be seamless and not include seams created by arranging (e.g., wrapping) the starting material layers together. Integral articles and devices may be desirable because they can be formed by methods that reduce undesirable features (e.g., voids, particle accumulation, or poor layer adhesion). These undesirable features can lead to device failure. Reducing these undesirable features can extend the life of the device and article.

[0056] The integral article can be formed from a polyethylene (PE) substrate. For example, the methods described herein can be used to form a PE substrate or PE structure into an integral PE article. For example, integral articles and devices can be produced by a method comprising the steps of: assembling a PE substrate on a first support and a second support; placing the first support, the PE substrate, and the second support in proximity to a housing; and applying a force to the first support, the PE structure, and the second support to form a PE article. The PE article can be integral and seamless. The PE article can also exhibit a range of desirable properties, such as durability, abrasion resistance, a smaller profile, high strength, and thromboresistance.

[0057] Figure 1 The methods shown are given as examples of various features of the method, and although combinations of these shown features are clearly within the scope of the invention, this example and its illustration are not meant to limit the concepts provided herein to Figure 1 fewer features, additional features, or alternative features of one or more of the features shown.

[0058] More specifically referring to Figure 1The method shown, according to some embodiments, provides a method 100 for forming a polyethylene (PE) article from a plurality of polyethylene (PE) substrates. The method 100 can be implemented in a variety of situations, including but not limited to the preparation or manufacture of medical devices, which may include implantable medical devices. Various forms of PE can be implemented in the method, including but not limited to films, membranes, tapes, tubes, etc. It is further understood that the PE can have various properties, including different thicknesses, fibril and node structures, porosities, densities, etc. Thus, the embodiments discussed herein are not limited to specific initial conditions or forms, but should be broadly understood to encompass any PE starting material suitable for the method.

[0059] In some embodiments, as Figure 1 shown, the method 100 for forming a PE article from a plurality of PE substrates may optionally include: providing a first support 110; assembling a plurality of PE substrates on the first support, wherein the plurality of PE substrates define a PE structure 120; applying a second support to the PE structure 130; positioning the first support, the PE structure, and the second support near a housing 140; and applying a force to the first support, the PE structure, and the second support to form the PE article 150.

[0060] Further referring Figure 1 to, when optionally providing the first support 110, the first support can be formed of silicone. In some embodiments, the first support can be similar to the first support 210 Figure 2 shown. In some embodiments, the first support is provided in the form of a silicone tube (see the first support 210 in Figure 2 ). However, the first support can be provided in any shape or size suitable for the application.

[0061] Further referring Figure 1 to, when assembling a plurality of PE substrates on the first support, wherein the plurality of PE substrates define a PE structure 120, the plurality of PE substrates can include but are not limited to discrete sheets, tapes, films, extrusion assemblies, or laminates of PE. The plurality of PE substrates can be provided in any size or thickness suitable for the application. Each of the plurality of PE substrates can have the same size or the same thickness, or can be provided in a variety of sizes and thicknesses. The plurality of PE substrates can also be provided in any shape suitable for the application. The PE substrates can be assembled on the first support in an environment suitable for the application or the material used. The environment can include but is not limited to a cooling (e.g., refrigerated) environment, a room temperature environment, or a heating environment.

[0062] In addition, the step of assembling a plurality of PE substrates (wherein the plurality of PE substrates define the PE structure 120) on the first support may further include assembling other substrates made of materials other than PE. It can be understood that, in addition to the PE substrates, substrates formed of other materials can also be used, such as expanded polyethylene (ePE), polytetrafluoroethylene (PTFE), and expanded polytetrafluoroethylene (ePTFE). Other absorbable or resorbable materials can also be considered. For example, a composite material can be formed according to the method described herein. The composite material can include multiple layers, such as a base layer and an outer layer. The multiple layers can include one or more material types. The base layer and the outer layer can include biostable materials (such as PTFE or PE) suitable for direct contact with blood or biological tissue.

[0063] Continuing to refer Figure 1 , when applying the second support to the PE structure 130, the PE structure can be located between the first support and the second support. In some embodiments, the second support can also be made of silicone. The second support can be similar to Figure 2 the second support 230 shown. In some embodiments, the second support is a silicone tube (see the second support 230 in Figure 2 ). However, the second support can be set to any shape or size suitable for the application. In some embodiments, the first support, the PE structure, and the second support can be cylindrical or tubular. This can be such that in a layered structure, the PE structure wraps around the first support, and the second support wraps around the PE structure (e.g., see Figure 2 and Figure 3 ). The cylindrical structure can be such that the first support is the internal support of the PE structure, and the second support is the external support of the PE structure. In other structures, the first support, the PE structure, and the second support can be flat, such that the layers are applied in a stacked structure. However, other configurations and shapes (such as spherical) can also be considered.

[0064] Further referring Figure 1 , when positioning the first support, the PE structure, and the second support near the housing 140, the housing can be set to any size or shape suitable for the application. The housing can be similar to Figure 2 and the housing 240 in Figure 3 . In some embodiments, the second support is located between the PE structure and the housing, such that the second support acts as a cushion for the PE structure. Positioning the first support, the PE structure, and the second support near the housing 140 can also include providing a mandrel around which the first support, the second support, and the PE structure are positioned. The mandrel can be similar to the mandrel 220 shown in Figure 2 . In some embodiments, the mandrel can be disposed within the housing.

[0065] Further reference is made to Figure 1 which includes applying forces to a first support member, a PE structure, and a second support member to form a PE article 150. Applying the forces can cause the first support member (e.g., the first support member 210 in Figure 2 ), the second support member (e.g., the second support member 230 in Figure 2 ), and the PE structure (e.g., the PE structure 200 in Figure 2 ) to expand or swell to conform to the shape of a housing (e.g., the housing 240 in Figure 2 ). In some embodiments, the housing can restrict the expansion of the first support member, the second support member, and the PE structure beyond the housing (the housing can restrict the expansion of the first support member, the second support member, and the PE structure so that their expansion does not exceed the housing), such that when the PE structure expands, a PE article (e.g., the PE article 260 in Figure 2 ) is formed. In some embodiments, when the PE structure expands, the PE structure conforms to the shape of the housing, thereby causing the PE article to assume the shape of the housing. In some embodiments, the surfaces of the first silicone support member and the second silicone support member can be provided with corrugations or textures such that when the forces are applied, the corrugations or textures are imprinted onto the PE structure. In some embodiments, forces are applied to the first support member, the PE structure, and the second support member to form a PE article 150, thereby forming an integral PE article. In some embodiments, an integral PE article can be defined as having the layers of the PE structure integrated (e.g., meshed) with each other. The integral PE article can be formed to be seamless and the individual layers of the PE structure are difficult to distinguish from each other. More details regarding changes in structure and material properties will be discussed in Example 1 and Example 2.

[0066] In some embodiments, an integral PE article can be formed such that the individual layers of the PE structure are integrated (e.g., meshed) with each other. In some embodiments, the integral PE article is formed without adhesive bonding. In some embodiments, the integral PE article is seamless such that the individual layers of the PE structure are difficult to distinguish. In some embodiments, the integral PE article is dense or non-porous. In some embodiments, the texture of the integral PE article is formed by the texture or corrugated surface of the first and second support members.

[0067] In some embodiments, when the starting material is an ePE structure, an integral ePE article is formed. The ePE structure can be processed by the method described above with respect to Figure 1 . In some embodiments, the integral ePE article is processed to be partially densified. In other embodiments, the integral ePE article is processed to be fully densified.

[0068] In some embodiments, a PE article (e.g., the PE article 260 in Figure 2 ) can be formed by the methods described herein, and the processing methods of these materials can endow them with properties such as higher durability, wear resistance, smaller profile, high strength, and antithrombogenicity. This may be due to better integration between the layers of the PE structure (e.g., by applying force rather than an adhesive), thereby reducing interlayer voids and reducing interlayer delamination, loosening, or spreading. By eliminating these properties, fewer potential failure points are formed in the PE article. Forming a seamless PE article can also reduce the points for failure propagation and reduce interlayer failures. This can in turn extend the service life of the PE article. In addition, forming a seamless PE article can also improve antithrombogenicity by reducing the areas where thrombus may form. The PE article formed by method 100 can have a thin-wall profile. In some embodiments, the thickness of the thin-wall profile of the PE article can be in the range of about 0.001 inches to about 0.040 inches. In some embodiments, the thickness can be in the range of about 0.001 inches to about 0.004 inches, about 0.004 inches to about 0.008 inches, about 0.008 to about 0.012 inches, about 0.012 inches to about 0.016 inches, about 0.016 inches to about 0.020 inches, about 0.020 inches to about 0.024 inches, about 0.024 inches to about 0.028 inches, about 0.028 inches to about 0.032 inches, about 0.032 inches to about 0.036 inches, and about 0.036 inches to about 0.040 inches. The thickness can be measured at the perimeter of the PE article after layer integration or engagement of the PE structure.

[0069] In some embodiments, the PE article can be formed as a medical device or a medical device component, or provided as a medical device or a medical device component. The medical device can include an implantable medical device. The PE article can be formed as a tubular structure and can be implemented, for example, as a graft. The PE article can be formed as a flat structure and can be implemented, for example, as a hernia patch, a cardiovascular patch, a neuromeninx, etc.

[0070] In some embodiments, applying force to the first support member, the PE structure, and the second support member to form the PE article 150 may also include heating the liquid to convert the liquid into a gas. In some embodiments, the liquid may be heated to about 130°C. In other embodiments, the liquid may be heated to a temperature between about 110-130°C, about 130-150°C, or 150-180°C. In some embodiments, the liquid may be liquid water, and the liquid water may be heated to a liquid water phase transition to steam. When the liquid undergoes a phase change, the gas expands and generates pressure, which applies force to the first support member, the PE structure, and the second support member. In some embodiments, the liquid may be heated while the liquid is in a mandrel, and the first support member, the PE structure, and the second support member are placed around the mandrel. In some embodiments, the mandrel is porous or perforated so that the gas can be released through the mandrel. In some embodiments, the mandrel is hollow to allow water to enter the interior of the mandrel. In some embodiments, heating the liquid into a gas may result in an expansion ratio of the liquid to the gas of about 1:1600.

[0071] In other embodiments, applying force to the first support member, the PE structure, and the second support member to form the PE article 150 may further include releasing compressed gas. In some embodiments, the released compressed gas may be released by placing the first support member (e.g., Figure 2 The first support member 210 in the PE structure (eg, Figure 2 PE structure 200) and a second support member (eg, Figure 2 The release of compressed gas can apply force to the first support member, the PE structure, and the second support member by the release rate of the compressed gas or by the pressure gradient inside (e.g., the side in contact with the gas) and outside the first support member, the PE structure, and the second support member. In some embodiments, the compressed gas can be inert. In some embodiments, the compressed gas can be stored in a mandrel (e.g., Figure 2 In some other embodiments, the housing can be connected to an external compressed gas source, wherein the external source applies compressed gas to the first support member, the PE structure and the second support member to apply force.

[0072] In some embodiments, the method 100 of forming a PE article from a plurality of PE substrates may further include heating the PE structure. Figure 2The PE structure (200) therein can be heated to a temperature higher than the melting temperature or glass transition temperature of the PE. This temperature can be about 130 °C, about 110 - 130 °C, about 130 - 150 °C, or about 150 - 180 °C. The heat can be provided by a heating environment (e.g., an oven). The heat can be applied by a heat source directly acting on the outer surface of the PE structure (e.g., the part of the PE structure in contact with the second support), or the heat can be applied by a heat source directly acting on the inner surface of the PE structure (e.g., the part of the PE structure in contact with the first support, or inside the lumen). In some embodiments, at least a portion of the heat applied to the PE structure is provided by the same mechanism as the force applied to expand the PE structure, e.g., a liquid is heated and transformed into a gas or compressed gas is released.

[0073] In some embodiments, heating the PE structure (e.g., Figure 2 the PE structure (200) therein) can be performed before applying forces to the first support, the PE structure, and the second support to form the PE article (150). In some embodiments, heating the PE structure can be performed while applying forces to the first support, the PE structure, and the second support to form the PE article (150). In some embodiments, applying heat to the PE structure will result in the formation of a monolithic structure (e.g., a seamless tube). In some embodiments, the PE structure can be formed into a medical device or a component of a medical device. In some embodiments where the PE structure contains ePE, applying heat and force to the PE structure will densify the PE structure.

[0074] In some embodiments, the PE structure is cooled after being heated. The PE structure can be cooled at room temperature, placed in an environment below room temperature (e.g., a refrigerator), or can be slowly cooled in an environment with a temperature higher than room temperature. In some embodiments, the environment for cooling the densified PE structure can be a stable temperature or a variable temperature. In some embodiments, the variable temperature of the environment allows the PE structure to cool at a controlled rate. The cooling rate of the PE structure can be constant or variable.

[0075] Figure 2 is a diagrammatic illustration of an embodiment of forming a PE article from a PE structure according to some embodiments. In some embodiments, Figure 2 The schematic diagram of Figure 1 follows the method 100 described regarding

[0076] Figure 2Shows the PE structure 200. In some embodiments, the PE structure 200 may include a plurality of PE substrates. In this embodiment, the PE structure 200 is in contact with the first support member 210. The PE structure 200 may be applied to the outer side of the first support member 210. In this embodiment, the inner side of the first support member 210 is in contact with the mandrel 220. The first support member may be applied to the outer surface of the mandrel. In this embodiment, the PE structure 200, the first support member 210, and the mandrel 220 are all shown as cylindrical. However, the PE structure 200, the first support member 210, and the mandrel 220 may also adopt other shapes, such as spherical, rectangular, etc.

[0077] The second support member 230 may be applied to the PE structure 200. In this embodiment, the second support member 230 is applied to the outer side of the PE structure 200 such that the PE structure 200 is located between the first support member 210 and the second support member 230. In this embodiment, the first support member 210, the PE structure 200, and the first support member 230 are all positioned around the mandrel 220. In some embodiments, the first support member 210 and the second support member 230 are made of silicone. However, embodiments in which the first support member 210 and the second support member 230 are made of flexible materials other than silicone are also contemplated.

[0078] The first support member 210, the PE structure 200, and the second support member 230 are located near the housing 240. In some embodiments, the mandrel 220 is part of the housing 240; in other embodiments, the mandrel 220 may be separated from the housing 240 and placed near the housing 240. In other embodiments, the mandrel 220 may be separated from the housing 240, and the housing 240 may be placed such that the housing 240 surrounds the mandrel 220. In this embodiment, the housing 240 has a cylindrical perimeter. However, depending on the target shape of the final PE product, the housing 240 may also adopt other perimeter shapes.

[0079] See Figure 2 , after placing the first support member 210, the PE structure 200, and the second support member 230 near the housing 240, a force 250 may be applied. The force 250 may be applied to the first support member 210, the PE structure 200, and the second support member 230 such that the first support member 210, the PE structure 200, and the second support member 230 expand to conform to the housing 240 (match the shape of the housing 240). The housing 240 may be positioned to limit the expansion of the first support member 210, the PE structure 200, and the second support member 230 so that they do not expand beyond the housing 240. When the PE structure 200 expands, the PE product 260 is formed.

[0080] In this embodiment, the force 250 is a radially outward radial force. In some embodiments, the force 250 applied to the PE structure can be a tensile force applied in the transverse or longitudinal direction. The tensile force can include stretching the PE structure to a longer length. In other embodiments, the force 250 applied to the PE structure can be a combination of a radial force and a tensile force. In the present embodiment, the mandrel 210 is porous or perforated such that the force 250 can be derived from the mandrel 220. In some embodiments, a liquid can be placed within the mandrel 220, where the liquid is heated such that the liquid phase transforms into a gas, the gas passes through the holes or perforations, and the gas applies the force 250. In other embodiments, compressed gas is released to apply the force 250.

[0081] Further referring Figure 2 , applying the force 250 to the PE structure forms the PE article 260. When the mandrel 220 and the outer shell 240 are removed, the formed PE article 260 undergoes plastic deformation and retains the expanded radial dimensions of the outer shell. The first support member 210 and the second support member 230 can undergo elastic deformation such that the first support member 210 and the second support member 230 temporarily maintain the expanded radial dimensions but may then rebound to a smaller size. This can enable the first support member 210 and the second support member 230 to be reused in future manufacturing. In the present embodiment, when the first support member 210 and the second support member 230 are removed, the PE article 260 continues to maintain the expanded radial dimensions. In some embodiments, the PE article 260 is a monolithic PE article. In some embodiments, the monolithic PE article is seamless. In this embodiment, the monolithic PE article 260 is formed without an adhesive, but rather by applying the force 250 to integrate or engage the layers of the PE structure to form the PE article.

[0082] In some embodiments, as described above with respect to Figure 1 , the PE article 260 can be formed to have desired properties such as higher durability, wear resistance, smaller profile, high strength, and thromboresistance.

[0083] In the present embodiment, the PE article 260 can be formed into a tubular structure and can be used, for example, as a graft. Other tubular medical devices or components are also contemplated.

[0084] Figure 3 is according to some embodiments, Figure 2Side view illustration of an embodiment. In this embodiment, the outer shell 240 is shown as having a shape with a constant circular cross-section. The constant circular cross-section of the outer shell 240 gives the PE article 260 a corresponding constant circular cross-section, which can result in a constant thickness of the PE article 260 along its length direction. This can form a PE article with a constant circular cross-section for a medical device or a medical device component. For example, a graft or a graft component can be formed. However, in some other embodiments, the outer shell 240 can have a variable cross-section. For example, in some embodiments, one end of the outer shell 240 can have a circular cross-section while the other end has a D-shaped cross-section. This can form a PE article with a variable cross-section for a medical device or a medical device component. For example, the variable cross-section outer shell 240 can be used to form a bifurcated graft or a bifurcated graft component. In other examples, some embodiments can have an outer shell with a variable thickness such that the PE article has a variable thickness along the length direction of the PE article 260.

[0085] In some embodiments, the layers of the PE structure 200 can be longitudinally wound around the first support 210 like a cigarette. However, other types of configurations can also be considered, including but not limited to helical winding. In some embodiments, a seam is formed longitudinally in the PE structure 200 before heating and expansion. However, in a method step (e.g., Figure 1 the method 100 described), this seam disappears, thus forming a seamless PE article 260 (e.g., a seamless tubular structure).

[0086] Figure 4 is a block diagram of a method 400 for forming an integral polyethylene (PE) article according to some embodiments. The method 400 can be implemented in a variety of situations, including but not limited to medical devices, which can include implantable medical devices.

[0087] In some embodiments, as Figure 4 shown, the method 400 for forming an integral polyethylene (PE) article can include: positioning the PE structure such that a first portion of the PE structure overlaps a second portion of the PE structure 410; applying heat to the PE structure 420; and expanding the PE structure while applying heat 430.

[0088] Further referring to Figure 4, when positioning the PE structure such that a first portion of the PE structure overlaps a second portion of the PE structure by 410, it should be understood that in some embodiments, the PE structure can be made of multiple PE substrates. In other embodiments, the multiple substrates can be other forms of polyethylene, including but not limited to ePE substrates or PTFE substrates. The multiple components can include but are not limited to discrete sheets, tapes, films, extruded components, or laminates. In some embodiments, the first portion of the PE structure (e.g., the first portion 510 in Figure 5 can be one of the multiple components, while the second portion of the PE structure (e.g., the second portion 520 in Figure 5 ) can be another of the multiple components. In some embodiments, the first portion of the PE structure and the second portion of the PE structure can have the same shape and size such that the overlapping portion of the first and second portions of the PE structure covers the other of the first and second portions of the PE structure. In other embodiments, the first portion of the PE structure and the second portion of the PE structure can have different shapes and sizes.

[0089] Positioning the PE structure such that a first portion of the PE structure overlaps a second portion of the PE structure by 410 can also include positioning the PE structure (e.g., the PE structure 500 in Figure 5 ) between a first silicone support (e.g., the first silicone support 515 in Figure 5 ) and a second silicone support (e.g., the second silicone support 525 in Figure 5 ). In some embodiments, the PE structure is sandwiched between the first silicone support and the second silicone support. In some embodiments, both the first silicone support and the second silicone support are tubular. In some embodiments, the PE structure is wound around the first silicone support such that the PE structure forms a PE structure tube. In some embodiments, the configuration of the PE structure tube is such that the second portion of the PE structure is located outside the first portion of the PE structure, as shown in Figure 5 . In other embodiments, the PE structure forms the opposite configuration, where the first portion of the PE structure is located outside the second portion of the PE structure. This configuration of the PE structure tube may only become apparent before heating and / or applying a force to the PE structure tube. The PE structure can have multiple layers that together make up the PE structure. In some embodiments, the PE structure is wound around a mandrel (e.g., the mandrel 530 in Figure 5 ).

[0090] For further reference Figure 4, heating the PE structure (420) can be carried out at a temperature around the melting temperature or glass transition temperature of the PE. In some embodiments, the heating temperature can be around about 130 °C, between about 110 - 130 °C, between about 130 - 150 °C, or between about 150 - 180 °C. In some embodiments, the heat can be provided by a heating environment (e.g., an oven). In some embodiments, the heat can be applied by a heat source directly acting on the outer surface of the PE structure (e.g., the part of the PE structure in contact with the second support), or the heat can be applied by a heat source directly acting on the inner surface of the PE structure (e.g., the part of the PE structure in contact with the first support, or inside the lumen).

[0091] Continuing to refer Figure 4 , expanding the PE structure 430 while applying heat can also include applying a force to one of the first silicone support and the second silicone support such that the first silicone support, the PE structure, and the second silicone support expand together. In some embodiments, the first silicone support, the PE structure, and the second silicone support expand together radially to form a tubular shape. In other embodiments, the first silicone support, the PE structure, and the second silicone support are compressed together axially (e.g., laterally or longitudinally) to form a flat structure. In further embodiments, the first silicone support, the PE structure, and the second silicone support expand together radially and axially. In some embodiments, heat can be applied through a mandrel (e.g., Figure 5 the mandrel 530 in

[0092] In some embodiments, expanding the PE structure 430 while applying heat can also include applying a force through pressure. In some embodiments, the heat and / or pressure is provided by heating a liquid to transform it into a gas. In some embodiments, the heating liquid is water and the gas is steam. The heating liquid transformed into a gas can be applied from the inside of the tubular PE structure to cause the tubular PE structure to expand radially. In some embodiments, the heating liquid can be disposed inside the mandrel (e.g., Figure 5 the mandrel 530 in

[0093] In other embodiments, the heat and / or pressure is provided by compressed gas. The compressed gas can include an inert compressed gas, and the pressure of the compressed gas can be applied to the inside of the tubular PE structure (e.g., through Figure 5 the mandrel 530 in Figure 5The PE structure therein 500) is exposed to the released compressed gas to apply heat and / or pressure. The release of the compressed gas can apply heat and / or pressure through the release rate of the compressed gas or the pressure gradient between the inner side (e.g., the side in contact with the gas) and the outer side of the tubular PE structure.

[0094] In some embodiments, expanding the PE structure while applying heat 430 can form a seamless, integral PE article. In this embodiment, since the integral PE article is seamless, the first part of the PE structure may be indistinguishable from the second part of the PE structure. The first part of the PE structure can engage or integrate with the second part of the PE structure.

[0095] In some embodiments, the integral PE article (e.g., Figure 5 the integral PE article 560 therein) can be formed by the methods described herein, and the processing methods of these materials can endow them with properties such as higher durability, wear resistance, smaller profile, high strength, and thromboresistance. This may be due to better integration between the layers of the PE structure (e.g., by applying force instead of an adhesive), thereby reducing the voids between the layers and reducing interlayer peeling, loosening, or spreading. By eliminating these characteristics, there are fewer potential failure points formed in the PE article. Forming a seamless PE article can also reduce the failure propagation points and reduce interlayer failures. This can in turn extend the service life of the integral PE article. In addition, forming a seamless PE article can also improve thromboresistance by reducing the areas where thrombus may form. The integral PE article formed by method 400 can have a thin-walled profile. In some embodiments, the thickness can be in the range of about 0.001 inches to about 0.004 inches, about 0.004 inches to about 0.008 inches, about 0.008 to about 0.012 inches, about 0.012 inches to about 0.016 inches, about 0.016 inches to about 0.020 inches, about 0.020 inches to about 0.024 inches, about 0.024 inches to about 0.028 inches, about 0.028 inches to about 0.032 inches, about 0.032 inches to about 0.036 inches, and about 0.036 inches to about 0.040 inches.

[0096] In some embodiments, the PE article can be formed as a medical device or a medical device component, or provided as a medical device or a medical device component. The medical device can include an implantable medical device. The PE article can be formed as a tubular structure and can be implemented, for example, as a graft. The PE article can be formed as a flat structure and can be implemented, for example, as a hernia patch, a cardiovascular patch, a neuromeninx, etc.

[0097] Figure 5FIG. 0 is a diagram of an embodiment of forming an integral (PE) article. In some embodiments, Figure 5 The schematic diagram of Figure 4 follows the method 400 described with respect to

[0098] Figure 5 FIG. 8 shows a first portion 510 of the PE structure and a second portion 520 of the PE structure that are offset from each other and partially overlap. In some embodiments, the first portion 510 and the second portion 520 of the PE structure may have the same shape and size. In other embodiments, the first portion 510 and the second portion 520 of the PE structure may have different shapes and sizes. The PE structure 500 may include a stack of overlapping PE portions, including the first portion 510 of the PE structure and the second portion 520 of the PE structure. In the present embodiment, the first and second portions of the PE structure have substantially the same shape and size such that the second portion 520 of the PE structure can completely cover the first portion 510 of the PE structure.

[0099] Similar to Figure 2 the embodiment shown, the PE structure 500 can be applied to the mandrel 530. In the present embodiment, the PE structure 500 is wound around the mandrel 530 to form a tube. In some embodiments, the PE structure 500 may be located between a first silicone support 515 and a second silicone support 525. In some embodiments, the first silicone support 515 and the second silicone support 525 are substantially the same as the first silicone support 210 in Figure 2 and the second silicone support 230 in Figure 2 . In addition, in some embodiments, the PE structure may be located near the housing 540. In some embodiments, the PE structure is located within the housing 540.

[0100] In some embodiments, the PE structure 500 can be heated at a temperature near the glass transition temperature of the material. The heating temperature can be about 130 °C, about 110 - 130 °C, about 130 - 150 °C, or about 150 - 180 °C. In some embodiments, the PE structure 500 can expand while being heated. Similar to Figure 2 FIG. 21, causing the PE to expand can include applying a force 550. In the present embodiment, the force 550 can be a radially outward force and can be applied by the mandrel 530. In some embodiments, the force 530 can be a pressure, where the pressure comes from the release of hot water turning into steam or compressed gas.

[0101] After heating the PE structure 500 and causing it to expand, a seamless integral PE article 560 is formed. The seamless PE article 560 is composed of a first portion 510 and a second portion 520 of the PE structure. However, when forming the seamless integral PE article 560, the first PE structure portion 510 and the second PE structure portion 520 are difficult to distinguish from each other and are integrated or meshed together.

[0102] In some embodiments, as described above with respect to Figure 4 the PE article 560 can be formed to have desired properties such as higher durability, wear resistance, smaller profile, high strength, and thromboresistance.

[0103] In this embodiment, the integral PE article 560 can be formed as a tubular structure and can be used, for example, as a graft. Other tubular medical devices or components are also contemplated.

[0104] Figure 6 is a block diagram of a method 600 of forming an expanded polyethylene (ePE) article using a forming support according to some embodiments. The method 600 can be implemented in a variety of situations, including but not limited to medical devices, which can include implantable medical devices.

[0105] In some embodiments, as Figure 6 shown, the method 600 of forming a PE article can include assembling a PE structure onto a first forming support 610, positioning a punch near the PE structure 620, applying a force 630 to the PE structure through the punch 620, applying heat to the PE structure 640, and releasing the punch from the PE structure to form a PE article 650.

[0106] Further referring to Figure 6 assembling the PE structure onto the first forming support 610 can also include using an auxiliary support to hold the PE structure in place (e.g., Figure 7 the auxiliary support 740 in Figure 7 ). In some embodiments, the first forming support (e.g.,

[0107] the first forming support 720 in Figure 6 the first forming support 720 in Figure 7 ) can be made of a rigid material. In other embodiments, the first forming support can be made of a compliant material (e.g., silicone). Figure 7)。In other embodiments, the shape of the forming punch may not correspond to the shape of the first forming support.

[0108] Further reference Figure 6 , applying a force 630 to the PE structure by the punch may further include applying a force to the PE structure by the punch such that the punch contacts the PE structure and pushes the PE structure into the first forming support. The PE structure may conform to the shape of the first forming support. In some embodiments (e.g., Figure 7 embodiments), the first forming support may have a concave shape, and the PE structure is pushed by the punch into the concave shape, and the PE structure is stretched to conform to the concave shape.

[0109] Further reference Figure 6 , heating the PE structure 640 may include heating the PE structure at a temperature near the melting temperature or glass transition temperature of the PE structure. The heating temperature may be about 130 °C, about 110 - 130 °C, about 130 - 150 °C, or about 150 - 180 °C. In some embodiments, heat may be applied to the PE structure by the punch such that the punch is a heating punch. In other embodiments, heat may be applied to the PE structure by the first forming support. In other embodiments, heat may be applied to the PE structure by the environment (e.g., an oven or a heating environment). In some embodiments, when the PE structure is inside the first forming support, heat is applied to the PE structure 640 to form a PE article (e.g., Figure 7 the PE article 760 in

[0110] In some embodiments, heating the PE structure 640 may densify the PE article. In some embodiments, the PE article has a density gradient throughout the article. In this embodiment, the part of the PE article with a higher density may be the part of the PE structure that is stretched the farthest to the shape of the first support (see Figure 7 the PE structure 710 in

[0111] In some embodiments, applying a force 630 to the PE structure by the punch and heating the PE structure 640 are performed simultaneously. In other embodiments, applying a force 630 to the PE structure by the punch is performed before heating the PE structure 640. In other embodiments, heating the PE structure 640 is performed before applying a force 630 to the PE structure by the punch.

[0112] Further reference Figure 6, releasing the punch from the PE structure to form the PE article 650 may further include the PE article retaining the shape of the first forming support. In some embodiments, the PE article is a monolithic PE article. In some embodiments, the monolithic PE article can be formed to have desired properties such as higher durability, wear resistance, smaller profile, high strength, and thromboresistance. This may be due to better integration and engagement between the layers of the PE structure (e.g., by applying force rather than an adhesive), thereby reducing interlayer voids and reducing interlayer delamination, loosening, or spreading. This in turn can reduce the failure points in the PE article. The formation of a seamless PE article can also reduce the failure propagation points. All of these can extend the service life of the PE article. In addition, the formation of a seamless PE article can also improve thromboresistance.

[0113] In some embodiments, the PE article can be formed as or provided as a medical device or a medical device component. The medical device can include an implantable medical device. The PE article can be formed as a tubular structure and can be implemented, for example, as a graft. The PE article can be formed as a flat structure and can be implemented, for example, as a hernia patch, a cardiovascular patch, a neuromeninx, etc.

[0114] Figure 7 is a side view illustration of an embodiment of forming an expanded polyethylene (ePE) article using a forming support according to some embodiments. In some embodiments, Figure 7 The schematic diagram follows the method 600 described with respect to Figure 6 as described.

[0115] Figure 7 Shows a PE structure 710 assembled onto a first forming support 720. In some embodiments, the PE structure 710 can include multiple PE substrates. In some embodiments, the multiple PE substrates can include, but are not limited to, discrete sheets, tapes, films, extruded components, or laminates of PE. In some embodiments, the first forming support 720 has a concave portion 715 that defines a first shape. In some embodiments, the PE structure 710 is held in place by an auxiliary support 740. In some embodiments, the first forming support is made of a flexible material (such as silicone). In other embodiments, the first forming support can be made of a rigid material. The first forming support 720 and the auxiliary support can be made of the same material or different materials. The punch 730 can be placed in a position close to the PE structure 710. In this embodiment, the punch 730 can also be placed in a position close to the auxiliary support group 740.

[0116] Further referring to Figure 7, a force 750 can be applied to the PE structure 710 by a punch 730. The force 750 can be applied such that the punch 730 contacts the PE structure 710 and pushes or pulls the PE structure 710 into or out of the first forming support 720. When the PE structure 710 is pushed into the first forming support 720, the PE structure 710 can conform to the shape 715 of the first forming support 720. In this embodiment, the PE structure 710 conforms to the concave shape 715 of the first forming support 720. In this embodiment, the PE structure 710 can be stretched or expanded when the force 750 is applied, such that the PE structure 710 stretches to conform to the concave shape 715. In some embodiments, a force can also be applied to the auxiliary support 740 to further shape the PE structure 710. In other embodiments, no force can be applied to the auxiliary support 740.

[0117] In some embodiments, the PE structure 710 can be heated while the force 750 is applied to the PE structure 710. The heating temperature can be near the glass transition temperature of the PE. The temperature can be about 130 °C, about 110 - 130 °C, about 130 - 150 °C, or 150 - 180 °C. In some embodiments, the PE structure 710 can be heated when the PE structure 710 is within the first forming support 720. In some embodiments, heating the PE structure 710 can densify the PE structure 710. In some embodiments, the PE structure 710 can be uniformly densified. In other embodiments, the PE structure 710 can be densified to form a density gradient across the entire PE structure 710.

[0118] See further Figure 7 , the punch 730 can be released from the PE structure 710 to form a PE article 760. In some embodiments, the PE article can retain the shape 715 of the first forming support 720. In some embodiments, the PE article retains the density gradient formed on the PE structure 710. In some embodiments, the PE article is a monolithic PE article. In some embodiments, the PE article is seamless.

[0119] Examples

[0120] Example 1

[0121] In the first example, three PE articles were heated to a temperature above the melting temperature. The first, second, and third PE articles 800, 802, 804 each included a first porous PE film. These three PE articles all included expanded polyethylene (ePE), but a similar concept can also be seen in other PE articles. The first PE article 800 was heated to about 127 °C, the second PE article 802 was heated to about 130 °C, and the third PE article 804 was heated to about 133 °C.

[0122] The first PE product 800, the second PE product 802, and the third PE product 804 are all formed into tubes and then heated. Heat is applied substantially uniformly to each of the first, second, and third PE products 800, 802, 804 using a mandrel, although other heat sources can also be used. When heating each of the first, second, and third PE products 800, 802, 804, the pressure is kept constant, but no vacuum is drawn. A constant low pressure of about 2 psi is applied using an outer wrapper.

[0123] Figure 8 A shows the first PE product 800 after being heated to 127 °C and then cooled. Figure 8 B shows the second PE product 802 after being heated to 130 °C and then cooled. It was observed that as the processing temperature increased above the melting temperature, the PE product melted, or the layers within the PE product melted, causing the material to shrink and densify. As shown, compared to the first PE product 800, there are fewer visible layers or less space within the second PE product 802, further indicating that the material is denser or more cohesive. The disappearance of the visible layers or the reduction in space within the PE product also indicates a more integrated structure with less distinction between the layers. Additionally, as shown, relative to the first PE product 800, the thickness of the second PE product 802 decreased and it became more compact. The second PE product 802 also appears to have become more tightly packed or denser, causing the microstructure to coalesce.

[0124] Referring back to Figure 9, after heating the products, the thicknesses (in micrometers (μm)) of the first, second, and third PE products 800, 802, 804 were measured. The data indicates that as the processing temperature increased above the melting temperature, the thickness of the corresponding product decreased. In other words, the thickness of the third PE product 804 is less than the thickness of the second PE product 802, and the thickness of the second PE product 802 is less than the thickness of the first PE product 800. As described in connection with Figure 8 A-8B, the decrease in thickness may be related to the densification and shrinkage of the PE product, the compression of the microstructure of the PE product, and a more integrated structure.

[0125] Referring to Figure 10 , the bubble points (in psi) of the first, second, and third PE products 800, 802, 804 were measured. The data indicates that as the processing temperature increased above the melting temperature, the bubble point of the corresponding product also increased. The bubble point may be related to the pore size in the PE product. An increase in the bubble point indicates a decrease in the pore size of the product. In other words, the pore size of the third PE product 804 is less than the pore size of the second PE product 802, and the pore size of the second PE product 802 is less than the pore size of the first PE product 800. As described in connection with Figure 8As described in A-8B, the increase in the bubble point may also be related to the densification and shrinkage of the PE article, and a structure with a higher degree of compression and / or integration of the microstructure of the PE article.

[0126] Reference Figure 11 , the air flow or the air leakage through the first, second, and third PE articles 800, 802, 804 was measured, in liters per hour (l / hr). The air flow measurement was performed using a leak detection device. As the processing temperature increased above the melting temperature, the air leakage of the corresponding article decreased. The air leakage may be related to the pore size present in the PE article, because the larger the pore size, the more air is allowed to leak through the PE article. This indicates that as the processing temperature increases, the pore size of the corresponding article decreases. In other words, the pore size of the third PE article 804 is smaller than that of the second PE article 802, and the pore size of the second PE article 802 is smaller than that of the first PE article 800. As described in conjunction with Figure 8 A-8B, the reduction in air leakage may be related to the densification and shrinkage of the PE article, and a structure with a higher degree of compression and / or integration of the microstructure of the PE article.

[0127] In addition, the pore size may correspond to the ability of the article to selectively allow or reduce the entry, growth, and / or attachment of cells within its structure. A smaller pore size may enable the corresponding article to reduce or limit the entry of cells through it, which may be desirable in certain applications, including but not limited to aortic devices. A larger pore size may enable the corresponding article to allow cells to enter through it. Therefore, the processing temperature can be selected as needed to increase or decrease the pore size to respectively allow or reduce cell growth within.

[0128] Although the above embodiments were described for tubular PE articles, flat PE articles or PE articles of other shapes may exhibit similar behavior and similar changes in material properties when heated above the melting temperature.

[0129] Example 2

[0130] In a second embodiment, three PE articles were heated to a temperature above the melting temperature. The fourth, fifth, and sixth PE articles 806, 808, 810 contain a second porous PE film, which is different from the first layer of porous PE film in Example 1. These three PE articles all contain expanded polyethylene (ePE), but similar concepts can also be seen in other PE articles. The fourth PE article 806 was heated to about 127 °C, the fifth PE article 808 was heated to about 130 °C, and the sixth PE article 810 was heated to about 133 °C.

[0131] Similar to Example 1, the fourth PE article 806, the fifth PE article 808, and the sixth PE article 810 were each formed into a tubular shape before heating. Heat was applied substantially uniformly to each of the fourth, fifth, and sixth PE articles 806, 808, 810 using a mandrel, although other heat sources could also be used. When heating each of the fourth, fifth, and sixth PE articles 806, 808, 810, the pressure was kept constant, but no vacuum was drawn. A constant low pressure of about 2 psi was applied using an outer package.

[0132] Similar to Example 1, the thickness, bubble point, and gas leakage of each of the fourth, fifth, and sixth PE articles 806, 808, and 810 were measured. The trends in the material properties were similar to those found in Example 1. As shown in FIG. 9, as the processing temperature was increased above the melting temperature, the thickness of the corresponding PE article decreased. As Figure 10 shown, as the processing temperature was increased above the melting temperature, the bubble point increased. As Figure 11 shown, as the processing temperature was increased above the melting temperature, the gas leakage of the corresponding article decreased. These results suggest that an increase in processing temperature may be related to the densification and shrinkage of the PE article, the compression of the microstructure of the PE article, the reduction in the pore size of the PE article, and / or a more overall structure. This also suggests that as the processing temperature increases, the densification, compression of the microstructure, reduction in pore size, and enhancement of the overall structure of the corresponding PE article are not limited to one type of porous ePE film, but can be observed in the first and second porous ePE films.

[0133] See Figure 12 , the peel strength of each of the fourth, fifth, and sixth PE articles 806, 808, 810 was measured. The peel strength was measured as the force required to peel the article by about 12 mm, in units of N / 12 mm. The data indicate that as the processing temperature was increased above the melting temperature, the peel strength of the corresponding article increased. In other words, the force required to pull the third PE article 804 was greater than the force required to pull the second PE article 802, and the force required to pull the second PE article 802 was greater than the force required to pull the first PE article 800. The increase in force may also be related to the densification and compaction of the PE article and / or the compression of the microstructure of the PE article. The increase in the force required to pull back the article indicates that as the processing temperature increases, the layers or spaces within the PE article decrease, and new bonds may form within the PE article. The increase in the pulling force also indicates that as the processing temperature increases, the PE article becomes more integrated because the layers within the article may become less distinct and more difficult to separate.

[0134] Although the above examples were described for tubular PE articles, flat PE articles or PE articles of other shapes may exhibit similar behavior and similar changes in material properties when heated above the melting temperature.

[0135] Although specific embodiments are provided herein, it should be understood that different arrangements and material properties can be selected and processed within the spirit of the present disclosure. In addition, the specific embodiments provide temperatures, steps, and properties that can be modified while still remaining within the spirit of the present disclosure.

[0136] The invention of the present application has been generally described above and in connection with specific embodiments. It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the invention. Accordingly, the embodiments are intended to cover such modifications and variations of the invention as long as they are within the scope of the appended claims and their equivalents.

Claims

1. A method of forming a polyethylene (PE) article, comprising: Assembling a plurality of polyethylene substrates on a first support, the plurality of polyethylene substrates defining a PE structure; Applying a second support to the PE structure such that the PE structure is located between the first support and the second support; Positioning the first support, the PE structure, and the second support in proximity to a housing; And Applying a force to the first support, the second support, and the PE structure such that the first support, the second support, and the PE structure expand to conform to the shape of the housing, Wherein the housing restricts the expansion of the first support, the second support, and the PE structure beyond the housing such that a PE article is formed when the PE structure expands.

2. The method according to claim 1, wherein Applying a force to the PE structure to form a monolithic PE article.

3. The method according to claim 2, wherein The monolithic PE article is seamless.

4. The method according to claim 1, wherein The method further comprises positioning the first support, the second support, and the PE structure around a mandrel.

5. The method according to claim 3, wherein The mandrel is porous or perforated.

6. The method according to claim 1, wherein, The first support and the second support are formed of silicone.

7. The method according to claim 1, wherein Assembling the plurality of polyethylene components further comprises assembling other components formed of materials other than PE, the materials other than PE including at least one of expanded polyethylene, polytetrafluoroethylene, or expanded polytetrafluoroethylene.

8. The method according to claim 1, wherein The method further comprises heating the PE structure.

9. The method according to claim 1, wherein Applying a force to the first support, the second support, and the PE structure includes heating a liquid located within the mandrel to about 130 degrees Celsius such that the liquid phase transforms into a gas that applies the force.

10. The method according to claim 8, wherein, Heating the liquid to a gas results in an expansion ratio of the liquid to the gas of about 1:1600.

11. The method according to claim 1, wherein, Applying a force to the first support, the second support, and the PE structure includes releasing compressed gas.

12. A method of forming a monolithic polyethylene (PE) article, comprising: Positioning a PE structure such that a first portion of the PE structure overlaps a second portion of the PE structure; Applying heat to the PE structure; And Expanding the PE structure while applying heat to the PE structure.

13. The method according to claim 12, wherein, Positioning the PE structure includes positioning the PE structure between a first silicone support and a second silicone support.

14. The method according to claim 13, wherein, Expanding the PE structure includes applying a force to one of the first silicone support and the second silicone support such that the first silicone support, the PE structure, and the second silicone support expand together.

15. The method according to claim 14, wherein, Expanding the PE structure includes applying a force by pressure.

16. The method according to claim 15, wherein, The pressure is provided by heating a liquid to a gas.

17. The method according to claim 15, wherein, The pressure is provided by using compressed gas.

18. The method according to claim 14, wherein, Expanding the PE structure while applying heat forms a seamless monolithic PE article.

19. A method of forming a polyethylene (PE) article, comprising: Assembling a PE structure onto a first forming support; Placing a punch in proximity to the PE structure; Applying a force to the PE structure through the punch such that the punch contacts the PE structure and pushes the PE structure into the first forming support, and the PE structure conforms to the shape of the first forming support; Applying heat to the PE structure; And Releasing the punch from the PE structure to form a PE article that retains the shape of the first forming support.

20. The method according to claim 19, wherein Applying heat to the PE structure includes heating to about 130 degrees Celsius.

21. The method according to claim 19, wherein, Applying heat to the PE structure densifies the PE article, and the density varies in a gradient across the entire PE article.

22. The method according to claim 19, wherein, Applying force to the punch and applying heat to the PE structure are carried out simultaneously.

23. The method according to claim 19, wherein, Heat is applied to the PE structure while the PE structure is located within the first forming support.

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