Processing of expanded polyethylene above melting point

Abstract

A method of processing expanded polyethylene (ePE), the method comprising: placing an ePE substrate on a heated component, the ePE substrate having a first size when the ePE substrate is heated on the heated component; taking down the ePE substrate from the heated component to cool and shrink the ePE substrate to a second size, where the second size is smaller than the first size; and forming the ePE substrate into an ePE article.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of U.S. Provisional Application No. 63 / 433,114, filed on December 16, 2022, which is incorporated herein by reference in its entirety for all purposes. Technical Field

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

[0004] Methods for processing materials are important because they can impart specific qualities to the processed materials. Specific qualities may be necessary for the processed materials to serve their intended purposes or may allow the processed materials to be used in new ways. In various industries, including but not limited to the medical device industry, and more specifically implantable medical devices, the choice of processing method is important. However, processed materials can be used in multiple industries, and the same properties required in one industry may also be important in other industries.

[0005] Medical devices often need to be adapted to the needs of the patient. For example, an implantable device made of a processed material may need to fit the length or diameter of a patient's lumen. However, it is costly to manufacture and store implantable devices in a variety of sizes in small increments. Implantable devices may only be available in specific intervals of sizes, which are determined by average sizes and then used based on the closest match. However, the closest match does not necessarily mean the tightest fit. In addition, the lumen diameter may vary along the length of the patient's lumen, so it may be difficult to determine the appropriate size of the implantable device. What is needed are materials that can be used to provide medical devices that can provide an optimal fit when implanted. Summary of the Invention

[0006] The present disclosure relates to a method for processing ePE and articles produced by the method. For example, the method and articles produced by the method include: exposing ePE to a temperature above the melting temperature during processing, which temperature is above the melting point of ePE, and the ePE exhibits desirable properties. These desirable properties may include: diameter adjustability, improved adhesion to metals, improved adhesion to other polyethylenes, the ability to store / record length, the ability to expand, and wear resistance.

[0007] According to an example ("Example 1"), a method for processing expanded polyethylene (ePE) includes: placing an ePE substrate having a first dimension on a heated component, heating the ePE substrate on the heated component, removing the ePE substrate from the heated component to cool and shrink the ePE substrate to a second dimension, wherein the second dimension is smaller than the first dimension, and forming the ePE substrate into an ePE article.

[0008] According to another example ("Example 2") based on Example 1, forming the ePE substrate into an ePE article includes: wrapping the ePE substrate around a mandrel.

[0009] According to another example ("Example 3") based on Example 2, forming the ePE substrate into an ePE article includes: melt-bonding the ePE substrate to itself along a longitudinal line.

[0010] According to another example ("Example 4") based on Example 1, placing the ePE substrate on the heated component includes providing the ePE substrate as an ePE sheet.

[0011] According to another example ("Example 5") based on Example 1, heating the ePE substrate on the heated component includes heating the heated component at about 110°C to 180°C.

[0012] According to another example ("Example 6") based on Example 1, the method further includes adhering the ePE article to metal.

[0013] According to another example ("Example 7") based on Example 1, the method further includes adhering the ePE article to another polyethylene structure.

[0014] According to another example ("Example 8") based on Example 1, the method further includes expanding at least a portion of the ePE article.

[0015] According to another example ("Example 9") based on Example 8, expanding at least a portion of the ePE article includes radial expansion.

[0016] According to another example ("Example 10") based on Example 8, expanding at least a portion of the ePE article includes longitudinal expansion.

[0017] According to an example ("Example 11"), a method for processing expanded polyethylene (ePE) includes: heating an ePE substrate to a temperature above the ePE melting temperature, the ePE substrate having a first dimension; cooling the ePE substrate, the ePE substrate shrinking to a second dimension when cooled, the second dimension being smaller than the first dimension; and forming the ePE substrate into an ePE article.

[0018] According to another example based on Example 11 (“Example 12”), the ePE substrate is heated at about 110 °C to 180 °C.

[0019] According to another example based on Example 11 (“Example 13”), the method further includes the step of expanding at least a portion of the ePE article.

[0020] According to another example based on Example 13 (“Example 14”), expanding at least a portion of the ePE article is performed at room temperature.

[0021] According to one example (“Example 15”), an ePE article made of expandable polyethylene (ePE) includes: an ePE substrate that has formed the ePE article, the ePE article being formed by shrinking an ePE sheet during a heating to cooling process, and the ePE article being capable of expanding.

[0022] According to another example based on Example 15 (“Example 16”), the ePE substrate is formed as a graft.

[0023] According to another example based on Example 15 (“Example 17”), using a mandrel, the ePE substrate is formed into an ePE article.

[0024] According to another example based on Example 15 (“Example 18”), the ePE article is capable of expanding in the longitudinal direction.

[0025] According to another example based on Example 15 (“Example 19”), the ePE article is capable of expanding in the radial direction.

[0026] According to another example based on Example 15 (“Example 20”), the ePE article is porous.

[0027] The above embodiments are merely examples and should not be construed as limiting or otherwise narrowing any scope of the inventive concept provided in other ways by the present disclosure. Although multiple embodiments are disclosed, other embodiments will become apparent to those skilled in the art from the following detailed description that shows and describes exemplary embodiments. Therefore, the drawings and the detailed description are considered to be illustrative in nature and not restrictive in nature.

[0028] Brief Description of the Drawings

[0029] The accompanying drawings are used to assist in further understanding of the present disclosure, which are incorporated into and constitute 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.

[0030] Figure 1is a block diagram of a method for processing expanded polyethylene (ePE) according to some embodiments, including a positioning step, a removing step, and a forming step;

[0031] Figure 2 is according to some embodiments Figure 1 of a method for processing expanded polyethylene (ePE), the method further including an expansion step;

[0032] Figure 3 is a block diagram of a method for processing expanded polyethylene (ePE) according to some embodiments, including a heating step, a cooling step, and a forming step;

[0033] Figure 4 is according to some embodiments Figure 3 of a method for processing expanded polyethylene (ePE), the method further including an expansion step;

[0034] Figure 5 shows an example of forming a tubular article from an ePE sheet according to some embodiments;

[0035] Figure 6 shows an example of forming a flat article from an ePE sheet according to some embodiments;

[0036] Figure 7 shows, according to some embodiments, Figure 5 an embodiment in which a tubular article expands to an intermediate size;

[0037] Figure 8 shows, according to some embodiments, Figure 6 an embodiment in which a flat article expands to an intermediate size;

[0038] Figure 9A and 9B shows the microstructure of the ePE substrate of Example 1 processed above the melting temperature;

[0039] Figure 10 shows the thickness data of the ePE substrates of Examples 1 and 2;

[0040] Figure 11 shows the bubble point data of the ePE substrates of Examples 1 and 2;

[0041] Figure 12 shows the air leakage data of the ePE substrates of Examples 1 and 2; and

[0042] Figure 13 shows the peel data of the ePE substrate of Example 2. Detailed Description

[0043] Definitions and Terms

[0044] The present disclosure is not meant to be read in a limiting sense. For example, the terms used in this application should be read broadly in the context of the meanings ascribed to these terms in the art.

[0045] For imprecise terms, the terms "about" and "approximately" may be used interchangeably to indicate that a measured value includes the measured value and also includes any measured value that is reasonably close to the measured value. As understood and readily determinable by one of ordinary skill in the relevant art, a measured value that is reasonably close to the measured value deviates quite slightly from the measured value. For example, such deviations may be attributable to measurement errors, differences in measurement and / or manufacturing equipment calibration, 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 an object by a person or machine, etc. If it is determined that the value of such a reasonably small difference is not readily determinable by one of ordinary skill in the relevant art, the terms "about" and "approximately" may be understood to mean plus or minus 10% of the stated value.

[0046] As used herein, the term "laminate" refers to multi-layered film-like materials, composite materials, or other materials, such as, but not limited to, polymers, such as, but not limited to, elastomers, elastomeric materials, or non-elastomeric materials, and combinations thereof.

[0047] As used herein, the term "membrane" generally refers to one or more of a membranous material, a composite material, or a laminate.

[0048] As used herein, the term "biocompatible material" 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 may include the first membrane and the second membrane as described herein for each embodiment.

[0049] As used herein, the term "polyethylene" (PE) includes all types of polyethylene, including, but not limited to, expanded polyethylene (ePE).

[0050] Description of Embodiments

[0051] Those skilled in the art will appreciate 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 drawings referenced herein are not necessarily drawn to scale and may, in some instances, be enlarged to illustrate various aspects of the present disclosure, and in this regard, the drawings should not be considered limiting.

[0052] Figure 1 and Figure 2The method shown is provided as an example of the various features of the method. Although combinations of the features shown are clearly within the scope of the present invention, the embodiments and their illustrations are not meant to limit the inventive concept provided herein to fewer features, additional features, or alternative features to Figure 3 and Figure 4 one or more of the features shown in Figure 1 and Figure 2 For example, in various embodiments, the processing steps shown in Figure 3 and Figure 4 may include the processing steps described with reference to Figure 3 and Figure 4 It should also be understood that the reverse is also true. Figure 3 and Figure 4 One or more of the components shown may be used as a supplement or alternative to the components shown in Figure 1 and Figure 2 For example, Figure 3 and Figure 4 the method steps of the method shown may be used in combination with the method steps of the method shown in Figure 1 and Figure 2

[0053] Figure 1 is a block diagram of a method 100 for processing expanded polyethylene (ePE) according to some embodiments. The method 100 may be implemented in various situations, including but not limited to medical devices, which may include implantable medical devices. Various forms of ePE may be implemented in these methods, including but not limited to membranes, films, ribbons, tubes, etc. It is further understood that ePE may have various characteristics, including: different thicknesses, fibril and node structures, porosity, density, etc. Therefore, the embodiments discussed herein are not limited to specific initial conditions or forms, but should be understood broadly as encompassing any ePE starting material suitable for the method.

[0054] In some embodiments, the method 100 for processing ePE includes: placing an ePE substrate on a heated component 110, removing the ePE substrate from the heated component 120, and forming the ePE substrate into an ePE article 130.

[0055] In some embodiments, when the ePE substrate is placed on the heated component, for example, as Figures 5-6The heated components 510, 610 are shown. Heat is transferred from the heated components to the ePE substrate, such that the ePE substrate is heated by the heated components. Although not limited to these embodiments, the heated components may include a press, a heating pad, an oven, etc. The heated components may be set to various temperatures, including but not limited to temperatures higher than the melting temperature of ePE. For example, the temperature of the heated components may be set to about 100 °C to about 180 °C. In some embodiments, the temperature of the heated components is set to 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, about 170 °C to about 180 °C. Before placing the ePE substrate on the heated component 110, the heated component may be set to any appropriate temperature, or after placing the ePE substrate on the heated component 110, the heated component may be heated to an appropriate temperature. In some embodiments, when the ePE substrate is placed on the heated component 110 and the heated component is at or above the melting temperature of ePE, the ePE substrate on the heated component may be heated to a temperature above the melting temperature of ePE. In some embodiments, the ePE substrate is heated without restraint. In other embodiments, the ePE substrate may be constrained in the X direction (e.g., horizontally), the Y direction (e.g., longitudinally), or in both the X direction and the Y direction. In some embodiments, placing the ePE substrate on the heated component 110 may further include: providing the ePE substrate as an ePE sheet. When the ePE substrate is heated on the heated component, the ePE sheet has a first dimension. The ePE sheet may be provided as a square, a rectangle, or other shapes. In one embodiment, the ePE sheet may be square (see Figure 5 ), and the first dimension may be defined by a first dimension L1 (see Figure 5 ).

[0056] Still referring to Figure 1, the method further includes: removing the ePE substrate 120 from the heated component. For example, after a specified time, after reaching the target ePE substrate temperature, or when the desired material properties are achieved, the ePE substrate is removed from the heated component. When removing the ePE substrate 120 from the heated component, the ePE substrate is removed from the heated component to cool the ePE substrate. The ePE substrate can be cooled at room temperature, can be placed in an environment colder than room temperature (such as a freezer), or can be slowly cooled in an environment with a temperature higher than room temperature. In some embodiments, the environment in which the ePE substrate is cooled can be at a stable temperature or at a variable temperature. In some embodiments, the variable temperature of the environment allows the ePE substrate to cool at a controlled rate. The cooling rate of the PE substrate can be constant or variable.

[0057] As the ePE substrate cools, the ePE substrate shrinks to a second dimension. The second dimension can be smaller than the first dimension. Continuing with the embodiment where the ePE sheet is a square sheet (e.g., as Figure 5 shown), the second dimension can be defined by a second dimension L2 (see Figure 5 ). The second dimension L2 ( Figure 5 ) can be smaller than the first dimension L1 ( Figure 5 ). Although reference is made here to the Figure 5 embodiment, a rectangular ePE sheet (e.g., as Figure 6 shown) can undergo a similar process and will experience similar dimensional changes upon cooling. Embodiments of the ePE rectangular sheet are further discussed with reference to Figure 6 . It can be understood that once the ePE substrate cools and the ePE is at or below a predetermined temperature, the shrinkage of the ePE substrate stops and the dimensions of the ePE substrate are stable. In some embodiments, the predetermined temperature can be the melting temperature of the ePE substrate. The predetermined temperature can depend at least in part on the type of ePE used (e.g., expanded low molecular weight polyethylene or expanded high molecular weight polyethylene). Once cooled, the ePE substrate is capable of expanding or distending at a temperature far below the melting temperature (e.g., room temperature). The ePE substrate is still capable of expanding or distending at a temperature above the melting temperature.

[0058] It should be understood that during the cooling process, as the ePE substrate shrinks, in some cases certain material properties may be imparted to the ePE substrate. For example, an ePE substrate that has cooled and shrunk may be capable of selective expansion or distention, better adhesion to secondary structures such as metals, PE, or other polymers, storage of length in the ePE substrate, expansion upon yielding, etc. Similar properties can be imparted when the ePE substrate expands or distends after cooling.

[0059] Still referring toFigure 1 After removing the ePE substrate 120 from the heated component, the ePE substrate is formed into an ePE article. Forming the ePE substrate into an ePE article 130 can, for example, result in the formation of Figures 5-6 ePE article 540 or the formation of ePE article 620. Forming the ePE substrate into an ePE article 130 can be carried out at the temperature of the heated component or an elevated temperature below that temperature. In some embodiments, the ePE article can be formed into a tubular article (e.g., Figure 5 tubular article 540), formed into a flat article (e.g., Figure 6 flat articles 620, 630, 640 or 650), formed into a film, or formed into a laminate made of multiple layers of processed ePE layers. Other articles can also be considered. In medical applications, the tubular article can be a graft, and the flat article can be a hernia patch, a cardiovascular patch, a nerve membrane, etc.

[0060] In some embodiments, forming the ePE substrate into an ePE article 130 can further include: wrapping the ePE substrate around a mandrel (e.g., Figure 5 mandrel 530). This can form the ePE substrate into a tubular article (e.g., Figure 5 tubular article 540). In addition to this embodiment, forming the ePE substrate into an ePE article 130 can further include adhering or attaching the ePE substrate to itself (e.g., adhering with an adhesive, fusion bonding, or mechanical attachment using sutures). In one embodiment, the adhesion or attachment of the ePE substrate to itself can be along a longitudinal line (e.g., Figure 5 longitudinal fusion bonding line 535). In other embodiments, the ePE substrate is adhered or attached to itself along a horizontal line, a diagonal line, etc. within a region. When the ePE is wrapped around a mandrel, the ePE sheet can be adhered or attached to itself.

[0061] In some embodiments, the method 100 of processing ePE can further include: attaching the ePE article to a metal or metal secondary structure. Adhering the ePE article to a metal or metal secondary structure can be carried out while forming the ePE substrate into an ePE article 130, or can be carried out after forming the ePE substrate into an ePE article. The metal or metal secondary structure can include a stent, a occluder, a shunt, a valve frame, etc.

[0062] In some embodiments, method 100 of processing ePE may further include: attaching an ePE article to polyethylene or a polyethylene secondary structure. Attaching the ePE article to polyethylene or a polyethylene secondary structure may be performed while forming the ePE substrate into the ePE article 130, or may be performed after forming the ePE substrate into the ePE article. The polyethylene or polyethylene secondary structure may include grafts, leaflets, etc.

[0063] Additionally, in some embodiments, method 100 of processing ePE may further include: attaching an ePE article to a polymer or a polymer secondary structure. The polymer may include polytetrafluoroethylene (PTFE), including but not limited to expanded polytetrafluoroethylene (ePTFE). Other polymer types may be considered.

[0064] Now refer to Figure 2 , a block diagram of method 200 of processing expanded polyethylene (ePE) according to some embodiments is provided. Method 200 may be implemented in various situations, including but not limited to medical devices, which may include implantable medical devices.

[0065] Method 200 of processing ePE includes: placing an ePE substrate on a heated member 210, removing the ePE substrate from the heated member 220 such that the ePE substrate is formed into an ePE article 230, and expanding at least a portion of the ePE article 240.

[0066] The method step of placing the ePE substrate on the heated member 210 may be substantially similar to the method step of placing the ePE substrate on the heated member 110 as described above with reference to Figure 1 . For example, the heated member may be the heated members 510, 610 as shown in Figures 5-6 . The method step of removing the ePE substrate from the heated member 220 may be substantially similar to the method step of removing the ePE substrate from the heated member 120 as described above with reference to Figure 1 . The method step of forming the ePE substrate into the ePE article 230 may be substantially similar to the method step of forming the ePE substrate into the ePE article 130 as described above with reference to Figure 1 . Forming the ePE substrate into the ePE article may for example include Figures 5-6 the ePE article 540 and / or the ePE article 620.

[0067] In some embodiments, after shrinking the ePE substrate, heat and / or pressure may be applied to the ePE substrate to limit the possible amount of expansion. This allows the ePE substrate to have a locked or specified amount of possible expansion. This may allow control of the size of the ePE article formed from the ePE substrate.

[0068] When forming an ePE substrate into an ePE article 230, the ePE article can expand. In some embodiments, at least a portion of the ePE article is expanded 240 at at least one location of the ePE article. In other embodiments, at least a portion of the ePE article can be expanded 240 over the entire ePE article. In some embodiments, when the ePE article is in a second size, expanding at least a portion of the ePE article 240 can cause the ePE article to expand back to a first size. In some embodiments, when the ePE article is in a second size, expanding at least a portion of the ePE article 240 can cause the ePE article to expand to an intermediate size between the first size and the second size. In some embodiments, the intermediate size can include an intermediate diameter (e.g., Figure 7 the intermediate diameter DI in Figure 8 ). In some embodiments, the intermediate size can further include an intermediate length (e.g., Figure 7 XI and YI in

[0069] ). In other embodiments, the intermediate size can include an intermediate diameter and an intermediate length (e.g., Figure 7 the intermediate diameter DI and the intermediate length HI in

[0070] ).

[0071] Figure 3 is a block diagram of a method 300 for processing expandable polyethylene (ePE) according to some embodiments. In some embodiments, Figure 3 the process of Figure 1Similarities. Method 300 can be implemented in various situations, including but not limited to medical devices, which may include implantable medical devices.

[0072] The method 300 for processing ePE may include: heating the ePE substrate to a temperature 310 higher than the melting temperature of ePE, cooling the ePE substrate 320, and shaping the ePE substrate into an ePE article 330.

[0073] Heating the ePE substrate to a temperature 310 higher than the melting temperature of ePE is carried out using a heating source. The heating source can be similar to the heated component described above with reference to Figure 1 The heated component. The heating source can be set to various temperatures, including but not limited to higher than the melting temperature of ePE. For example, the temperature of the heating source can be set to about 100 °C to about 180 °C. In some embodiments, the temperature of the heating source is set to 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, about 170 °C to about 180 °C. The heating source can include but not limited to: presses, heating pads, ovens, etc. In some embodiments, for example, the heating source can be similar to the heated components 510, 610 as Figures 5-6 Shown. In other embodiments, the heating source can be an indirect heating source, such as an environment set to the target temperature for heating the ePE substrate.

[0074] In some embodiments, heating the ePE substrate to a temperature 310 higher than the melting temperature of ePE can be carried out when the ePE substrate is unconstrained. When unconstrained, the ePE substrate can shrink or collapse when heated. In other embodiments, the ePE substrate can be constrained in the X direction (e.g., horizontally), the Y direction (e.g., longitudinally), or in both the X direction and the Y direction. The ePE substrate can be fully or partially constrained in the X direction and / or the Y direction. When constrained, the shrinkage or collapse of the ePE substrate in the constrained direction can be restricted or prevented. When the ePE substrate is heated to a temperature higher than the melting temperature of ePE, the ePE substrate has a first dimension.

[0075] Still referring to Figure 3, the method 300 of processing ePE further includes: cooling the ePE substrate 320. The ePE substrate can be cooled by removing / taking down the ePE from the heating source. For example, after a specified time, after reaching the target ePE substrate temperature, or when the desired material properties are achieved, the ePE substrate can be removed / taken down from the heating source to cool the ePE substrate. The ePE substrate can be cooled at room temperature, can be placed in an environment colder than room temperature (such as a freezer), or can be slowly cooled in an environment with a temperature higher than room temperature. In some embodiments, the environment in which the ePE substrate is cooled can be at a stable temperature or at a variable temperature. In some embodiments, the variable temperature of the environment cools the ePE substrate at a controlled rate. The cooling rate of the PE substrate can be constant or variable. When cooled, the ePE shrinks or retracts to a second dimension. The second dimension can be smaller than the first dimension. It can be understood that once the ePE substrate is cooled and the ePE is at or below a predetermined temperature, the shrinkage of the ePE substrate stops and the size of the ePE substrate stabilizes. The predetermined temperature can be the melting temperature of the ePE substrate. It should be understood that during the cooling process, as the ePE substrate shrinks, in some cases specific material properties may be imparted to the ePE substrate. For example, the cooled and shrunk ePE substrate may include selective swelling, better adhesion to secondary structures such as metals, PE, or other polymers, stored length in the ePE substrate, expansion at yield, etc. In some embodiments, the predetermined temperature can be the melting temperature of the ePE substrate. The predetermined temperature can depend at least in part on the type of ePE used (e.g., expanded low molecular weight polyethylene or expanded high molecular weight polyethylene). Once cooled, the ePE substrate is capable of swelling or distending at a temperature far below the melting temperature (such as room temperature). The ePE substrate is still capable of swelling or distending at a temperature higher than the melting temperature.

[0076] Still referring to Figure 3 , after cooling the ePE substrate, the ePE substrate can be formed into an ePE article. In some embodiments, the ePE substrate of the second dimension can be formed into an ePE article. Forming the ePE substrate into an ePE article 330 can be carried out at an elevated temperature, the elevated temperature being equal to or lower than the temperature of the heating source. In some embodiments, the ePE article can be formed into a tubular article (e.g., Figure 5 tubular article 540), formed into a flat article (e.g., Figure 6 flat articles 620, 630, 640, or 650), formed into a film, or formed into a laminate made of multiple processed ePE layers. Other articles can also be considered. In medical applications, the tubular article can be a graft, and the flat article can be a hernia patch, a cardiovascular patch, a nerve membrane, etc.

[0077] In some embodiments, forming the ePE substrate into the ePE article 330 may further include: wrapping the ePE substrate around a mandrel (such as Figure 5 the mandrel 530). This may form the ePE substrate into a tubular article (such as Figure 5 the tubular article 540). In addition to this embodiment, forming the ePE substrate into the ePE article 130 may further include adhering or attaching the ePE substrate to itself (e.g., adhering with an adhesive, fusion bonding, or mechanically attaching using sutures). In one embodiment, the adhesion or attachment of the ePE substrate to itself may be along a longitudinal line (such as Figure 5 the longitudinal fusion bond line 535). In other embodiments, it is contemplated to adhere or attach the ePE substrate to itself along a horizontal line, diagonal line, etc. When the ePE is wrapped around a mandrel, the ePE sheet may be adhered or attached to itself.

[0078] Now referring to Figure 4 , a block diagram of a method 400 for processing expanded polyethylene (ePE) is provided according to some embodiments. In some embodiments, Figure 4 the process is similar to Figure 3 . The method 400 for processing ePE may be implemented in various situations, including but not limited to medical devices, which may include implantable medical devices.

[0079] The method 400 for processing ePE includes a plurality of method steps. The method portion may include: heating the ePE substrate to a temperature above the ePE melting temperature, cooling the ePE substrate 420 such that the ePE substrate is formed into an ePE article 430, and expanding at least a portion of the ePE article 440.

[0080] The method step of heating the ePE substrate to a temperature 410 above the ePE melting temperature may be substantially similar to heating the ePE substrate to a temperature 310 above the ePE melting temperature as described above with reference to Figure 3 . For example, the heating source may be similar to the heating source described above with reference to Figure 3 . The method step of cooling the ePE substrate 420 may be substantially similar to cooling the ePE substrate 320 as described above with reference to Figure 3 . The method step of forming the ePE substrate into an ePE structure 430 may be substantially similar to the method step of forming the ePE substrate into an ePE structure 330 as described above with reference to Figure 3 . Forming the ePE substrate into an ePE structure 430 may, for example, include: forming an ePE structure 540 (see Figure 5 ) and / or forming an ePE structure 620 (see Figure 6 ).

[0081] In some embodiments, after the ePE substrate is shrunk, heat and / or pressure may be applied to the ePE substrate to limit the possible amount of expansion. This allows the ePE substrate to have a locked or specified amount of possible expansion. This may allow for control of the dimensions of the ePE article formed from the ePE substrate.

[0082] The ePE structure is capable of expansion. In some embodiments, expansion of at least a portion of the ePE structure 440 is performed only on a portion of the structure (e.g., at a specified longitudinal position). In some embodiments, the portion of the structure is at least one end of the ePE structure. In other embodiments, the portion of the structure is at the middle of the ePE structure between the two ends. In other embodiments, expansion of at least a portion of the ePE structure 440 may be performed on the entire structure. In some embodiments, expansion of at least a portion of the ePE structure 440 may cause the ePE structure to expand back from a second dimension to a first dimension. In some embodiments, expansion of at least a portion of the ePE structure 440 may cause the ePE structure to expand to an intermediate dimension between the first dimension and the second dimension. In some embodiments, the intermediate dimension may include an intermediate diameter (e.g., Figure 7 the intermediate diameter DI in Figure 8 ). In some embodiments, the intermediate dimension may further include an intermediate length (e.g., Figure 7 the XI and YI in

[0083] ). In other embodiments, the intermediate dimension may include an intermediate diameter and an intermediate length (e.g.,

[0084] In some embodiments, at least a portion of the ePE structure can be expanded 440 while the ePE structure is at room temperature (e.g., about 25°C - 30°C). In some embodiments, the expansion can be performed using a balloon (e.g., an angioplasty balloon). In some embodiments, the amount of expansion of the ePE article is limited such that the ePE article is expanded to a predetermined size using the balloon. In some embodiments, expanding at least a portion of the ePE structure 440 is done by the manufacturer of the ePE structure. In some embodiments, expanding at least a portion of the ePE structure 440 can be performed by the user or another party other than the manufacturer. In some embodiments, expanding at least a portion of the ePE structure 240 is done by a doctor before, during, or after a surgical procedure.

[0085] Figure 5 Embodiment 500 showing the formation of a tubular article from an ePE substrate according to some embodiments. In some embodiments, the ePE substrate is an ePE sheet 515. The ePE sheet 515 can be similar to the ePE substrate described above with reference to Figures 1-4 The ePE sheet 515 is provided as a starting material for forming the tubular article 540. In this embodiment, the tubular article 540 is an ePE structure as described above with reference to Figures 1-4 In some embodiments, the tubular article 540 is a graft. The method of forming the tubular article 540 generally can follow Figure 1 and Figure 2 and / or Figure 3 and Figure 4 The methods described in

[0086] The ePE sheet 515 is placed on a heated member 510 (e.g., a heat press). The heated member 510 is heated to a target temperature. For example, the target temperature of the heated member 510 can be set to about 100°C to about 180°C. In some embodiments, the temperature of the heat source is set to 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, about 170°C to about 180°C. In this embodiment, on the heated member 510, the ePE sheet 515 is unconstrained. In this embodiment, the ePE sheet 515 is approximately square and is defined by a first length L1.

[0087] Remove / take out the ePE sheet 515 from the heated member 510. After taking out from the heated member 510, cool the ePE sheet 515 as described regarding taking out the ePE substrate from the heated members 120, 220 and / or cooling the ePE substrates 320, 420. After cooling, the ePE sheet 515 shrinks into a smaller ePE sheet 520. The smaller ePE sheet 520 is defined by a second length L2. In this embodiment, the second length L2 is less than the first length L1. In this embodiment, the smaller ePE sheet 520 retains the generally square shape of the ePE sheet 515, but other configurations can also be considered, where the smaller ePE sheet 520 shrinks into a generally rectangular shape or a non-uniform shape in the X direction (e.g., horizontal) and the Y direction (e.g., longitudinal).

[0088] Then, form the smaller ePE sheet 520 into a tubular article 540. To form the tubular article 540, wrap the smaller ePE sheet 520 around a mandrel 530. In this embodiment, the mandrel 530 is tubular with a diameter M1. The smaller ePE sheet 520 wrapped around the mandrel 530 can be melt-bonded to itself along a longitudinal line to form a longitudinal melt-bonding line 535. Excess material 525 can be removed (e.g., cut off) from the smaller ePE sheet 520 to form the tubular article 540. In this embodiment, the tubular article 540 has a first diameter D1. The first diameter D1 can be substantially similar to the mandrel diameter M1.

[0089] The tubular article 540 is capable of expanding into an expanded tubular article 550. The tubular article 540 can expand when cooled. In this embodiment, the tubular article 540 can expand radially after the ePE sheet 515 shrinks. The tubular article 540 can be radially expanded using a balloon. In one embodiment, the expanded tubular article 550 can have only a radially expanded portion, such that the expanded tubular article 550 increases to a second diameter D2 at one end. In another embodiment, the middle portion of the tubular article 540 can be radially expanded. In other embodiments, the entire tubular article 540 can be radially expanded. In other embodiments, the tubular article 540 can be radially expanded and longitudinally expanded.

[0090] Figure 7 An embodiment is shown where, according to some embodiments, Figure 5 the tubular article 540 expands to an intermediate size. Figure 7Shows a tubular article 540 having a first diameter D1 and a first length H1. Generally, the first diameter D1 and the first length H1 define a first size of the tubular article 540. The tubular article 540 can be radially expanded to an expanded tubular article 550, which has a second diameter D2 and is longitudinally expanded to a second length H2. Generally, the second diameter D2 and the second length H2 define a second size of the tubular article 540 or the expanded tubular article 550. In some embodiments, the tubular article 540 can be expanded to an intermediate tubular article 545 having an intermediate size. The intermediate size is between the first size and the second size. In this embodiment, the tubular article 540 is expanded in both the radial direction and the longitudinal direction. In other embodiments, the tubular article 540 can be expanded in only one of the radial direction and the longitudinal direction. In this embodiment, the intermediate size is defined by an intermediate diameter DI and an intermediate length HI. In some embodiments, the tubular article 540 can be expanded from the first size to the intermediate size at a first temperature to produce the intermediate tubular article 545. Then, the intermediate tubular article 545 can be expanded from the intermediate size to the second size at a second temperature to produce the expanded tubular article 550. In some embodiments, the first temperature is higher than the second temperature. In some examples, the second temperature is room temperature.

[0091] Figure 6 Shows an embodiment 600 of forming a flat article 620 from an ePE substrate according to some embodiments. In this embodiment, the ePE substrate is an ePE sheet 615. The ePE sheet can be similar to the ePE substrate described above with reference to Figures 1-4 The ePE sheet 615 is provided as a starting material for forming the flat article 620. In this embodiment, the flat article 620 is an ePE structure as described above with reference to Figures 1-4 In some embodiments, the flat article 620 can be a hernia patch, a cardiovascular patch, a neuromeninx, etc. The flat article can also be a film or a multi-layer laminate. The method of forming the flat article 620 can generally follow Figure 1 and Figure 2 and / or Figure 3 and Figure 4 the methods described in

[0092] The ePE sheet 615 can be placed on a heated member 610 (e.g., a T-shirt press), which can be similar to the heated member 510 ( Figure 5)。The heated component 610 is heated to a target temperature. For example, the target temperature of the heated component can be set to about 110°C to about 180°C. In some embodiments, the temperature of the heated component 610 is set to 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, about 170°C to about 180°C. In this embodiment, on the heated component 615, the ePE sheet 610 is unconstrained. In other embodiments, the ePE sheet 615 can be constrained in the X direction (e.g., horizontally), the Y direction (e.g., longitudinally), or in both the X direction and the Y direction. In this embodiment, the ePE sheet 615 can be approximately rectangular in shape and is defined by a first X dimension X1 and a first Y dimension Y1. Other shapes of the ePE sheet 615 (e.g., square or irregular shape) can also be considered.

[0093] Remove the ePE sheet 610 from the heated component 615. As described above regarding removing the ePE substrate from the heated components 120, 220 and / or cooling the ePE substrates 320, 420, cool the ePE sheet 615. After being removed from the heated component 610, the ePE sheet 615 shrinks or contracts to a smaller ePE sheet 620. The smaller ePE sheet 620 is defined by a second X dimension X2 and a second Y dimension Y2. In this embodiment, the smaller ePE sheet 620 retains the generally rectangular shape of the ePE sheet 615, but other configurations can also be considered, where the smaller ePE sheet 620 contracts into a non-uniform shape in the X direction and the Y direction. In one embodiment, the smaller ePE sheet 620 is a flat product 620.

[0094] The ePE substrate or the flat product 620 is formed by shrinking (e.g., naturally shrinking) the ePE sheet 615 through the heating and cooling method as described above with reference to Figures 1-4 The flat product 620 can expand when cooled. The flat product 620 can expand longitudinally or horizontally after the ePE sheet 615 shrinks. In one embodiment, the flat product 620 can expand in the X direction (e.g., horizontally) and the Y direction (e.g., longitudinally) to form an XY flat product 630. The XY flat product is defined by a third X dimension X3 and a third Y dimension Y3. In some embodiments, the third X dimension X3 and the third Y dimension Y3 are respectively greater than the second X dimension X2 and the second Y dimension Y2 of the flat product 620. In some embodiments, the third X dimension X3 and the third Y dimension Y3 are respectively less than the first X dimension X1 and the first Y dimension Y1 of the ePE sheet 615. In some other embodiments, the third X dimension X3 and the third Y dimension Y3 are respectively the same as the first X dimension X1 and the first Y dimension Y1 of the ePE sheet 615.

[0095] In some embodiments, the flat article 620 can expand only in the Y direction (e.g., longitudinally) to form the Y flat article 640. This can occur if the ePE sheet 615 is partially or fully constrained in the X direction (e.g., horizontally) during the heating and cooling process. The Y flat article 640 is defined by a fourth X dimension X4 and a fourth Y dimension Y4. In some embodiments, the fourth X dimension X4 is the same as the second X dimension X2 of the flat article 620. In some embodiments, the fourth Y dimension Y4 is greater than the second Y dimension Y2 of the flat article 620. In some embodiments, the fourth Y dimension Y4 is less than the first Y dimension Y1 of the ePE sheet 615. In other embodiments, the fourth Y dimension Y4 is the same as the first Y dimension Y1 of the ePE sheet 615.

[0096] In some embodiments, the flat article 620 can expand only in the X direction (e.g., horizontally) to form the X flat article 650. This can occur if the ePE sheet 615 is partially or fully constrained in the Y direction (e.g., longitudinally) during the heating and cooling process. The X flat article 650 is defined by a fifth X dimension X5 and a fifth Y dimension Y5. In some embodiments, the fifth Y dimension Y5 is the same as the second Y dimension Y2 of the flat article 620. In some embodiments, the fifth X dimension X5 is greater than the second X dimension X2 of the flat article 620. In some embodiments, the fifth X dimension X5 is less than the first X dimension X1 of the ePE sheet 615. In other embodiments, the fifth X dimension X5 is the same as the first X dimension X1 of the ePE sheet 615.

[0097] Figure 8 An embodiment is shown in which, according to some embodiments, Figure 6 the flat article expands to an intermediate size. Figure 8Shows a flat article 620 having a second X dimension X2 and a second Y dimension Y2. Generally, the second X dimension X2 and the second Y dimension Y2 define a first dimension of the flat article 620. The flat article can expand horizontally and longitudinally to an XY flat article 630 having a third X dimension X3 and a third Y dimension Y3. Generally, for the XY flat article 630, the third X dimension X3 and the third Y dimension Y3 define a second dimension of the flat article 620. In some embodiments, the flat article 620 can expand to an intermediate flat article 625 having an intermediate dimension between the first dimension and the second dimension. In this embodiment, the intermediate dimension is defined by an intermediate X dimension XI and an intermediate Y dimension YI. In some embodiments, the flat article 620 can expand from the first dimension to the intermediate dimension to produce the intermediate flat article 625 at a first temperature. Then, the intermediate flat article 625 can expand from the intermediate dimension to the second dimension to produce the XY flat article 630 at a second temperature. In some embodiments, the first temperature is higher than the second temperature. In some examples, the second temperature is room temperature. Although this embodiment is described above with reference to the XY flat article 630, a similar intermediate dimension can be formed prior to the Y flat article 640 and the X flat article 650.

[0098] As described above with respect to Figures 1-8 the ePE substrate may experience changes in its material properties during the heating and cooling process. Prior to processing, the ePE substrate may exhibit high porosity, high surface area, and high crystallinity. In some embodiments, after the ePE substrate is shrunk by the heating and cooling process, the shrunk ePE or ePE structure may have reduced porosity and reduced surface area. In some embodiments, after the ePE substrate is shrunk by the heating and cooling process, the shrunk ePE may have a porosity similar to that before the heating and cooling process, where the pore diameter after shrinkage is smaller than the pore diameter before shrinkage. However, the shrunk ePE does not shrink to a completely dense state. Instead, the shrunk ePE can have pores with smaller dimensions than the starting material, such that the ePE substrate maintains its porosity throughout the processing, as Figures 1-4 shown. In some embodiments, the smaller pore diameter may not be deformed in shape relative to the pores of the ePE substrate before processing. In other embodiments, the smaller pore diameter may be deformed in shape relative to the pores of the ePE substrate before processing. Further details of the material property changes are discussed with respect to Examples 1 and 2.

[0099] Similarly, the microstructure of the ePE substrate may change during shrinkage. Prior to processing, the starting ePE substrate may have a microstructure consisting essentially of nodes and fibrils of varying lengths. In some embodiments, the fibrils may be tortuous (serpentine) fibrils. In some embodiments, the fibrils may all be tortuous fibrils substantially. In some embodiments, the shrunk ePE may retain a microstructure similar to that of the ePE substrate prior to processing. However, in some embodiments, during processing and shrinkage of the ePE substrate, the shorter fibrils may be lost. In some embodiments, during shrinkage, the microstructure of the shrunk ePE may reform or new connections may be created. For example, the new connections may be between fibril and fibril, fibril and node, or node and node. These new connections may occur in any direction. The new connections may reduce the pore size of the shrunk ePE substrate, but the shrunk ePE substrate remains porous. When the shrunk ePE substrate expands, at least some of the new connections may break, resulting in an increase in pore size. In some embodiments, when manufacturing a laminate or another ePE article having an ePE layer, new connections may be established in the microstructure between the ePE layers during shrinkage. Further details of the microstructure and other structural changes are discussed with respect to Examples 1 and 2.

[0100] The expansion ratio between the precursor ePE or starting ePE material and the shrunk ePE substrate may be affected by the thermal and / or expansion history of the precursor ePE. For example, the ePE precursor may initially have been directionally expanded (e.g., in the X, Y, Z, and / or radial directions, or any combination thereof), such that the ePE substrate shrinks in the same directionality. This may occur due to the alignment of the fibrils of the precursor ePE microstructure, where retraction is aligned with the fibrils. Similarly, the ePE substrate may expand in alignment with the fibrils. In this regard, to control the shrinkage and expansion directionality of the ePE substrate, the alignment of the fibrils of the precursor ePE microstructure can be controlled.

[0101] In other embodiments, the presence or absence of constraints in the X, Y, Z, radial, or any combination thereof directions may affect the directional shrinkage and expansion of the ePE substrate. In some embodiments, the fibrils may align in the X direction (e.g., the horizontal direction) upon shrinkage such that the shrunk ePE can only shrink and expand in the X direction. This may occur if the ePE sheet is constrained in the Y direction (e.g., the longitudinal direction) during the heating and cooling process. In other embodiments, the fibrils may align in the Y direction upon shrinkage such that the shrunk ePE can shrink and expand in the Y direction. This may occur if the ePE sheet is constrained in the X direction during the heating and cooling process. Similarly, the ePE substrate may be constrained in the Z direction (e.g., in thickness) or radially (e.g., with a mandrel) to affect the fibril orientation. Additionally, the alignment of shrinkage and expansion may affect the direction in which new connections in the microstructure form upon shrinkage and break upon expansion. In this regard, to control the directional shrinkage and expansion of the ePE substrate, the ePE substrate may be restricted.

[0102] Example

[0103] Example 1

[0104] In a first embodiment, three ePE substrates are heated to a temperature above the melting temperature. The first ePE substrate 700 is heated to about 127 °C, the second ePE substrate 702 is heated to about 130 °C, and the third ePE substrate 704 is heated to about 133 °C. The first, second, and third ePE substrates 700, 702, 704 each comprise a first porous ePE film.

[0105] The first ePE substrate 700, the second ePE substrate 702, and the third ePE substrate 703 are each formed into a tubular shape and then heated. Heat is applied substantially uniformly to each of the first, second, and third ePE substrates 700, 702, 704 using a mandrel, although other heat sources may also be used. When heating each of the first, second, and third ePE substrates 700, 702, 704, the pressure is kept constant without applying a vacuum. A constant low pressure of about 2 psi is applied using an outer package.

[0106] Figure 9A The first ePE substrate 700 after being heated to 127 °C and then cooled is shown. Figure 9BShows the second ePE substrate 702 after being heated to 130 °C and then cooled. As observed, as the processing temperature rises above the melting temperature, the ePE substrate melts, causing the material to shrink and densify. As shown in the figure, the thickness of the second ePE substrate 702 decreases relative to the first ePE substrate 700 and is denser. The second ePE substrate 702 also appears to be tightened or densified, compressing the microstructure. In addition, compared to the first ePE substrate 700, the second ePE substrate 702 has fewer visible delaminations or less space within the ePE substrate, further indicating a greater degree of densification or a denser material.

[0107] Go to Figure 10 , after heating the corresponding substrates, the thicknesses of the first, second, and third ePE substrates 700, 702, 704 are measured in micrometers (μm). As the data shows, as the processing temperature increases, the thickness of the corresponding substrate decreases. In other words, the thickness of the third ePE substrate 704 is less than the thickness of the second ePE substrate 702, and the thickness of the second ePE substrate 702 is less than the thickness of the first ePE substrate 700. As referred to Figures 9A-9B As described, the decrease in thickness may be related to the densification and shrinkage of the ePE substrate and / or the compression of the ePE substrate microstructure.

[0108] Go to Figure 11 , the bubble points of the first, second, and third ePE substrates 700, 702, 704 are measured in psi. As the data shows, as the processing temperature rises above the melting temperature, the bubble points of the corresponding substrates also increase. The bubble point may be related to the pore size present in the ePE substrate. As the bubble point increases, this indicates a decrease in the pore size of the substrate. In other words, the pore size of the third ePE substrate 704 is less than the pore size of the second ePE substrate 702, and the pore size of the second ePE substrate 702 is less than the pore size of the first ePE substrate 700. As referred to Figures 9A-9B As described, the increase in the bubble point may be related to the densification and shrinkage of the ePE substrate and / or the compression of the ePE substrate microstructure.

[0109] In addition, the pore size can correspond to the ability of the article to selectively allow or reduce the entry, ingrowth, and / or attachment of cells within its structure. A smaller pore size can allow 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 can allow 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 allow or reduce cell ingrowth, respectively.

[0110] Go to Figure 12, the air flow or air leakage through the first, second, and third ePE substrates 700, 702, 704 was measured in liters per hour (l / hr). The air flow measurement was performed using a leak detection device from . As the processing temperature increased, the air leakage of the corresponding substrate decreased. The air leakage volume may be related to the pore size present in the ePE substrate, as larger pore sizes will allow more air leakage through the ePE substrate. This indicates that as the processing temperature increases, the pore size of the corresponding substrate decreases. In other words, the pore size of the third ePE substrate 704 is smaller than the pore size of the second ePE substrate 702, and the pore size of the second ePE substrate 702 is smaller than the pore size of the first ePE substrate 700. As described with reference to Figures 9A-9B , the decrease in air leakage may be related to the densification and shrinkage of the ePE substrate and / or the compression of the ePE substrate microstructure.

[0111] Although the above embodiments are described for tubular ePE substrates, flat ePE substrates or ePE substrates of other shapes may exhibit similar behavior and similar changes in material properties when heated above the melting temperature.

[0112] Example 2

[0113] In the second embodiment, three ePE substrates were heated above the melting temperature. The fourth ePE substrate 706 was heated to approximately 127 °C, the fifth ePE substrate 708 was heated to approximately 130 °C, and the sixth ePE substrate 710 was heated to approximately 133 °C. The fourth, fifth, and sixth ePE substrates 706, 708, 710 each included a second porous ePE membrane, which was different from the first porous ePE membrane of Example 1.

[0114] Similar to Example 1, before heating, the fourth ePE substrate 706, the fifth ePE substrate 708, and the sixth ePE substrate 710 were each formed into a tubular shape. Heat was applied substantially uniformly to each of the fourth, fifth, and sixth ePE substrates 706, 708, 710 using a mandrel, but other heating sources could also be used. When heating each of the fourth, fifth, and sixth ePE substrates 706, 708, 710, the pressure was kept constant without a vacuum. A constant low pressure of approximately 2 psi was applied using an outer package.

[0115] Similar to Example 1, the thickness, bubble point, and air leakage of each of the fourth, fifth, and sixth ePE substrates 706, 708, 710 were measured. The trends in material properties were similar to those found in Example 1. As Figure 10 shown, as the processing temperature increased above the melting temperature, the thickness of the corresponding ePE substrate decreased. As Figure 11As shown, as the processing temperature increases above the melting temperature, the bubble point increases. As Figure 12 shown, as the processing temperature increases above the melting temperature, the air leakage of the corresponding ePE substrate decreases. These results suggest that increasing the processing temperature may be related to the densification and shrinkage of the ePE substrate, the compression of the microstructure of the ePE substrate, and / or the reduction of the pore size of the ePE substrate. This also indicates that as the processing temperature increases, the densification, microstructure compression, and pore size reduction of the corresponding ePE substrate are not limited to one type of porous ePE film, but can be observed in the first and second porous ePE films.

[0116] Turning to Figure 13 , the peel strength of each of the fourth, fifth, and sixth ePE substrates 706, 708, 710 was measured. The peel strength was measured as the force to peel the substrate backward by approximately 12 mm, in units of N / 12 mm. As shown by the data, as the processing temperature increases above the melting temperature, the peel strength of the corresponding substrate also increases. In other words, the force required to pull the third ePE substrate 704 is greater than the force required to pull the second ePE substrate 702, and the force required to pull the second ePE substrate 702 is greater than the force required to pull the first ePE substrate 700. The increase in force may also be related to the densification and compaction of the ePE substrate and / or the condensing of the microstructure of the ePE substrate. The increased force required to pull the substrate back indicates that as the processing temperature increases, the layers or spaces within the ePE substrate decrease, and new bonds can form within the ePE substrate.

[0117] Although the above embodiments are described for tubular ePE substrates, flat ePE substrates or ePE substrates of other shapes may exhibit similar behaviors and similar changes in material properties when heated above the melting temperature.

[0118] 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 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 for processing expanded polyethylene (ePE), the method comprising: Placing an ePE substrate on a heated member, the ePE substrate having a first dimension; Heating the ePE substrate on the heated member; Removing the ePE substrate from the heated member, allowing the ePE substrate to cool and shrink to a second dimension, wherein the second dimension is less than the first dimension; and Forming the ePE substrate into an ePE article.

2. The method according to claim 1, wherein, Forming the ePE substrate into an ePE article includes wrapping the ePE substrate around a mandrel.

3. The method according to claim 2, wherein, Forming the ePE substrate into an ePE article includes melt-bonding the ePE substrate to itself along a longitudinal line.

4. The method according to claim 1, wherein, Placing the ePE substrate on the heated member includes providing the ePE substrate in the form of an ePE sheet.

5. The method according to claim 1, wherein, Heating the ePE substrate on the heated member includes heating the heated member at about 110°C to 180°C.

6. The method according to claim 1, the method further comprising adhering the ePE article to a metal.

7. The method according to claim 1, the method further comprising adhering the ePE article to another polyethylene structure.

8. The method according to claim 1, wherein the method further comprises: Expanding at least a portion of the ePE article.

9. The method according to claim 8, wherein, Expanding at least a portion of the ePE article includes radial expansion.

10. The method according to claim 8, wherein, Expanding at least a portion of the ePE article includes longitudinal expansion.

11. A method for processing expanded polyethylene (ePE), the method comprising: Heating an ePE substrate to a temperature above the ePE melting temperature, the ePE substrate having a first dimension; Cooling the ePE substrate, the ePE substrate shrinking to a second dimension upon cooling, the second dimension being less than the first dimension; and Forming the ePE substrate into an ePE article.

12. The method according to claim 11, wherein, Heating the ePE substrate at about 110°C to 180°C.

13. The method according to claim 11, the method further comprising the step of expanding at least a portion of the ePE article.

14. The method according to claim 13, wherein, Expanding at least a portion of the ePE article is performed at room temperature.

15. An ePE article made of expanded polyethylene (ePE), comprising: The ePE substrate has been formed into an ePE article, the ePE article being formed by shrinking an ePE sheet during a heating-to-cooling process, the ePE article being capable of expanding.

16. The ePE article according to claim 15, wherein, The ePE substrate is formed into a graft.

17. The ePE article according to claim 15, wherein, Using a mandrel, the ePE substrate is formed into an ePE article.

18. The ePE article according to claim 15, wherein, The ePE article is capable of expanding in the longitudinal direction.

19. The ePE article according to claim 15, wherein, The ePE article is capable of expanding in the radial direction.

20. The ePE article according to claim 15, wherein, The ePE article is porous.

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