Patent Publication Number: US-11661286-B2

Title: Vacuum holder with extensible skirt gasket

Description:
FIELD OF THE INVENTION 
     The present disclosure relates to a vacuum holder for articles, a combination of a vacuum holder and an article, a carrier with autonomous vacuum, a system for holding and conveying articles, and a method for holding and conveying articles. 
     BACKGROUND 
     Various apparatuses and methods of holding and conveying articles are disclosed in the patent literature and on the internet. Patent publications disclosing apparatuses and methods of holding and/or conveying articles include: U.S. Pat. No. 3,229,953, Muir, Jr.; U.S. Pat. No. 3,426,884, Donner; U.S. Pat. No. 3,941,237, MacGregor, Jr.; U.S. Pat. No. 5,154,380, Risca; U.S. Pat. No. 5,651,941, Stark, et al.; U.S. Pat. No. 8,813,951, Forsthoevel, et al.; U.S. Pat. No. 9,032,880 B2, King, et al. (assigned to MagneMotion, Inc.); U.S. Pat. No. 9,085,420 B2, Williams, et al.; and, U.S. Pat. No. 9,193,108 B2, Seger, et al. Some types of vacuum holding devices are shown on the following internet sites: www.hysitron.com; www.toolocity.com; and www.vacmotion.com. 
     Many current conveyor systems use plastic “pucks” to transport bottles around the conveying systems. Such conveyor systems suffer from a number of drawbacks. The plastic pucks are often made to only fit one size and shape of an article, such as a bottle. The pucks also obstruct portions of the article so that it is not possible to apply decorations such as labels, stickers, shrink sleeves, and the like to the portions of the article behind the puck. 
     In conveyors in which an article is held in place on a conveyor by vacuum, the conveyor will typically have a hose that runs from a vacuum pump that is tethered to portion of the conveyor holding the article. As a result, at least a portion of the hose would ordinarily be required to travel along with the part of the conveyor to which it is attached. 
     Therefore, a need exists for, among other things, improved apparatuses and methods of holding and conveying articles. 
     SUMMARY 
     The present disclosure relates to: a vacuum holder for articles, a combination of a vacuum holder and an article, a carrier with autonomous vacuum, a system for holding and conveying articles, and a method for holding and conveying articles. 
     The vacuum holder may be used in many applications which currently utilize suction cups to adhere to the surface of an article. The vacuum holder, in certain uses, represents an improvement over suction cups with benefits that are not possible with suction cups. In some cases, a vacuum holder is provided for holding one or more articles. The vacuum holder has a retaining surface for holding one or more articles against the retaining surface by vacuum. The vacuum holder has a vacuum port at the retaining surface, a valve in fluid communication with the vacuum port through a passageway extending from the valve to the vacuum port. The valve can be closed so that after a vacuum is drawn, the vacuum holder can hold an article by vacuum untethered from attachment to a vacuum source. 
     In some cases, the vacuum holder can comprise an elastically extensible gasket adjacent at least a portion of the outer surface of the main body of the vacuum holder. The extensible gasket has an opening therein, and when the gasket is stretched and relaxed, the opening is sized and configured for fitting around the portion of the surface of the article to be held against the retaining surface of the vacuum holder and at least some portions of the article adjacent thereto. Such a gasket can be stretched and relaxed in any suitable manner and by any suitable stretching or expanding mechanism. 
     In other cases, the vacuum holder can comprise one part of a combination of a vacuum holder and an article. In such cases, at least one of the retaining surface of the vacuum holder and the surface of the article may be configured to provide a space between the retaining surface and the surface of the article wherein the space has an at least partial vacuum therein. 
     In other cases, the vacuum holder can comprise at least a portion of a vehicle or carrier with autonomous vacuum. The vehicle or carrier is, therefore, not required to be continuously in contact with a vacuum source. The vehicle can optionally comprise runners or wheels to facilitate movement of the vehicle. 
     In other cases, a system is provided for holding and conveying articles comprises the vacuum holder vehicle, a conveyor for moving the vacuum holder vehicle with an article held thereon from a first location to a second location, and a vacuum station along the conveyor. The vacuum station can draw a vacuum through the valve on the vacuum holder until an article is held against the vacuum holder. The vacuum holder with the article held thereon can then be conveyed untethered from a vacuum source. 
     In other cases, a method for holding and conveying articles is provided. The method comprises placing an article adjacent to the retaining surface of the vacuum holder, and drawing a vacuum at a vacuum station so that the article is held against the retaining surface of the vacuum holder. The method further comprises closing the valve so that the article is held against the retaining surface of the vacuum holder without being connected to the vacuum station. The vacuum holder with the article held thereon can then be conveyed untethered from a vacuum source. 
     Any of the embodiments described in this specification may be combined, or provided with any of the features of any other embodiment described herein in any suitable combinations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view of one non-limiting embodiment of a vacuum holder. 
         FIG.  2    is a cross-sectional view of the vacuum holder in  FIG.  1    taken along line  2 - 2  of  FIG.  1   . 
         FIG.  3    is a perspective view of a vacuum holder with an article (a bottle) thereon. 
         FIG.  4    is a simplified schematic cross-sectional view of the vacuum holder with a bottle thereon taken along line  4 - 4  of  FIG.  3    (without the gasket and top plate, and with the bottle being fragmented), along with a vacuum source. 
         FIG.  5    is a schematic cross-sectional view of another embodiment of a vacuum holder with a bottle thereon (the bottle being fragmented). 
         FIG.  6    is a schematic cross-sectional view of another embodiment of a vacuum holder with a bottle thereon (the bottle being fragmented). 
         FIG.  6 A  is a perspective view of another embodiment of a vacuum holder showing a bottle positioned above the vacuum holder and an extensible gasket, wherein the vacuum holder is configured to stretch the extensible gasket (the gasket being shown in an unstretched condition). 
         FIG.  6 B  is a perspective view of the vacuum holder shown in  FIG.  6 A  showing the gasket in a stretched condition, and the bottle placed inside an opening in the gasket. 
         FIG.  6 C  is a schematic cross-sectional view of the bottle with the gasket forming a skirt around the base of the bottle. 
         FIG.  6 D  is a perspective view of an alternative gasket having a volcano-shaped configuration. 
         FIG.  6 E  is a perspective view of a stretching/expanding mechanism for stretching an extensible gasket shown without the gasket and with the mechanism in an unextended configuration. 
         FIG.  6 F  is a perspective view of the expanding mechanism in  FIG.  6 E  shown without the gasket and with the mechanism in an extended configuration. 
         FIG.  6 G  is an enlarged perspective view of the sliding gripper assembly used in the expanding mechanism shown in  FIGS.  6 E and  6 F . 
         FIG.  6 H  is a perspective view showing how the optional arms of the stretching/expanding mechanism can be folded over to push the gasket (not shown) down on the top of the vacuum holder. 
         FIG.  6 I  is a plan view of another type of expanding mechanism for stretching an extensible gasket. 
         FIG.  6 J  is a cross-section view of the expanding mechanism shown in  FIG.  6 I  taken along lines  6 J- 6 J. 
         FIG.  6 K  is a cut-away perspective view of the expanding mechanism shown in  FIG.  6 I , showing the gasket in a first condition. 
         FIG.  6 L  is a cut-away perspective view of the expanding mechanism shown in  FIG.  6 I , showing the gasket in a second condition. 
         FIG.  6 M  is a cut-away perspective view of the expanding mechanism shown in  FIG.  6 I , showing the gasket in a third condition. 
         FIG.  7    is a perspective view of a vacuum holder that is provided with wheels and is joined to a component comprising a motive mechanism in order to form a vehicle. 
         FIG.  8    is a schematic cross-sectional view of another embodiment of a vacuum holder which is capable of holding multiple articles. 
         FIG.  9    is a schematic side view of an embodiment of a vacuum holder having a pair of holding features thereon. 
         FIG.  10    is a schematic cross-sectional view of an alternative embodiment of a vacuum source. 
         FIG.  11    is a schematic plan view of one non-limiting embodiment of a system and method for holding and conveying articles. 
         FIG.  12    is a stress/strain curve for several materials, some of which are suitable for use as elastically extensible gasket materials. 
     
    
    
     The embodiments of the method, apparatus(es), and articles shown in the drawings are illustrative in nature and are not intended to be limiting of the invention defined by the claims. Moreover, the features of the invention will be more fully apparent and understood in view of the detailed description. 
     DETAILED DESCRIPTION 
     The present disclosure relates to: a vacuum holder for articles, a combination of a vacuum holder and an article, a carrier with autonomous vacuum, a system for holding and conveying articles, and a method for holding and conveying articles. 
       FIGS.  1  and  2    show one non-limiting embodiment of a vacuum holder  20 . The vacuum holder  20  comprises a holder body (or “main body”)  22  and a valve  24 . The main body  22  has an outer surface  22 A and may have a fluid (e.g., gas or air) passageway (or “passageway”)  26  therein that leads to the outer surface  22 A. The vacuum holder  20  has a retaining surface  28  for contacting the surface of an article. The valve  24  is joined to the main body  22  and is in fluid communication with the passageway  26 . In the embodiment shown in  FIG.  1   , the vacuum holder  20  further comprises several optional components which comprise a gasket  30 , a top plate  32 , and an O-ring  34 . 
     The vacuum holder  20  described herein provides autonomous untethered vacuum therefore, it is not required to be continuously in contact with a vacuum source. The term “untethered”, as used herein, means that the vacuum holder is not connected to a vacuum source such as a vacuum pump or vacuum hose. It also means that the vacuum holder is not connected to any vacuum-creating mechanism that displaces air such as a handle that provides a cranking mechanism or other movement that is activated by a human for creating a vacuum, or a bellows or the like. The vacuum holder may be used in many applications which currently utilize suction cups to adhere to the surface of an article. The vacuum holder, in certain uses, represents an improvement over suction cups with benefits that are not possible with suction cups. 
     In other cases, the vacuum holder  20  can comprise at least a portion of a vehicle or carrier with autonomous vacuum. The vehicle or carrier is, therefore, not required to be continuously in contact with a vacuum source. When it is said that the vacuum holder can comprise at least a portion of a vehicle or carrier, it is meant that the vacuum holder  20  itself could comprise a vehicle or a carrier. In another example, the vacuum holder  20  may form a portion of a vehicle and when the vacuum holder is combined with another component (such as a motive mechanism, or part of a motive mechanism, that is capable of moving the vacuum holder  20 ) it could form a vehicle or carrier. In another example, the vacuum holder may be physically associated with (e.g., joined to), in any useful orientation, a vehicle or carrier that is capable of moving the vacuum holder. 
     The vacuum holder  20  can be used to adhere to and/or convey numerous different types of three dimensional articles  10 . Such articles include, but are not limited to: bottles, cans, cups, containers, tubs or trays for holding multiple individual products, bags, cartons, flow wraps, tampon tubes, and deodorant stick containers. Although pucks can be subject to the disadvantages described above, the vacuum holder could also be used to convey pucks and other carriers which hold articles therein. While the vacuum holder  20  can easily transport conventionally-shaped articles (e.g., cylindrical, and/or symmetrical articles), the vacuum holder  20  shown in  FIG.  1    is particularly suited to transport and control articles having shapes that are challenging to transport by other types of conveyors and pucks. The vacuum holder  20  can, for example, be used to transport: bottles with angled and/or off-center necks; asymmetrical bottles; bottles of non-constant cross-section, etc. The same vacuum holder can securely transport different article shapes, including different bottom shape and area surfaces, without need for any physical modification to the vacuum holder which is unlike many pucks and other types of conveyors. Similarly, the vacuum holder may comprise mechanisms to further secure the article to the holder that are integral to the holder rather than as part of a separate puck. Such mechanisms may consist of arms, straps, pins, depressions, and the like that may extend inwardly towards or outwardly from the surface of the vacuum holder. Such mechanisms may contact the article at one or more points beyond the portion of the article that is secured to the holder by means of the vacuum. Such mechanisms can advantageously be positioned to as to not interfere with any operations that might be performed on the article while secured to the holder such as decoration operations or filling operations in the case where the article is a container. 
     The articles  10  may have at least two opposing ends. For example, a bottle will have a top  12  and a base (or bottom)  14 . The articles  10  have a surface  16  which comprises the outside (or exterior) of the article except for any opening(s) in the article. The surface  16  may comprise the bottom  14  and a front, a back, and/or sides of the article. The articles  10  may be solid as in the case of some toothbrush handles, or hollow in the case of bottles, for example. If the articles are hollow, they will also have an interior. For bottles and other containers, the interior may be accessible from the environment through one or more openings such as for receiving and dispensing fluent material. Such openings will typically be capable of being closed or sealed. Any openings may be provided, for example, at the top, bottom, or on the sides of the articles. The surface of the articles  10  may be flat or curved. The entire surface need not be either flat or curved. The curved surface may be simple or complex. For example, the surface of the articles  10  may have: portions that are flat; portions that are curved; or, the surface may have both flat portions and curved portions. For instance, in the case of bottles, at least a portion of the surface may have a convex curvature. It is also possible that some articles may have a surface in which a portion thereof has a concave curvature. 
     The main body  22  is any component that is suitable for containing the valve  24 , or having the valve  24  at least indirectly joined thereto. The main body  22  may also provide, at least indirectly, a surface for retaining an article, including a structure for allowing the application of a vacuum to the article  10  to hold the article against the surface of the vacuum holder  20 . The surface  28  against which the article is held is referred to herein as the “retaining surface” of the vacuum holder  20 . In some cases, the main body  22  may also provide, at least indirectly, a surface for supporting an article. The outer surface  22 A of the main body  22  is the surface of the main body  22  located nearest the surface of the article when the vacuum holder  20  holds an article. The main body  22  also has an opposed surface  22 B that is located furthest from the surface of the article when holding an article, and sides  22 C. When the main body  22  is described herein as providing a surface for supporting an article (and holding the article against its surface), this includes holding the article directly against the outer surface  22 A of the main body  22 , as well as holding the article indirectly against the outer surface  22 A of the main body  22 . An example of holding an article indirectly against the outer surface  22 A of the main body  22  comprises holding the article against the outer surface  22 A of the main body where the gasket  30  (and/or top plate  32 , or other element) lies between the article  10  and the outer surface  22 A of the main body  22 . Depending upon the surface of the vacuum holder  20  that is directly presentable to a surface  16  of the article, the retaining surface  28  of the vacuum holder may comprise the outer surface  22 A, the top plate  32  or the gasket  30 . 
     The vacuum holder  20  and the main body  22  can be of any suitable configuration. If the article will rest on the vacuum holder  20  by gravity and be supported by the vacuum holder, then the vacuum holder  20  may be in the configuration of a platform for holding one or more articles.  FIGS.  1 - 3    show one non-limiting embodiment of the vacuum holder  20 . In this embodiment, the vacuum holder has the configuration of a generally rectangular prism. In this embodiment, the vacuum holder provides a rectangular platform for supporting one or more articles  10 . In other embodiments, the platform can be circular, disk shaped, or any other suitable shape having any number of sides which outline any shaped platform such as including, but not limited, to the inclusion of geometric shapes in whole or part from the listing of a: simple, complex, concave or convex polygon; trapezoid; parallelogram; rhombus; diamond; ellipse; oval; or circle. Of course, the overall size/footprint of the vacuum holder  20  can be scaled up for larger articles, the holding of multiple articles, or, scaled down for one or more smaller articles. 
     The configuration of the retaining surface  28  may vary depending on the configuration of the portion of the surface of the article  10  which is intended to be held by the vacuum holder  20 . Suitable configurations include those in which at least one of the retaining surface  28  and the portion of the surface of the article to be held is configured to provide a void space between the surface of an article and the retaining surface  28  of the vacuum holder  20 . This void space provides a vacuum chamber  40  from which air can be evacuated to form an at least partial vacuum between the retaining surface  28  of the vacuum holder  20  and the surface  16  of the article. 
     The void space can be of any suitable size (that is, volume) and shape. The vacuum holder  20  can provide some holding benefit if there is no void space between the retaining surface  28  of the vacuum holder  20  and the surface  16  of the article. In such a case, the area on the surface of the article held by the vacuum holder  20  may only be the size of the area of the vacuum port. However, the holding force in such an embodiment may be relatively low. Therefore, it is typically desirable to provide a void space that interacts with a greater area on the surface  16  of the article than the area of the vacuum port. 
       FIG.  4    shows that, in some cases, such as those in which the surface of the article  10  to be held has a concavity therein, the retaining surface  28  may have any suitable configuration so long as it is capable of contributing to form a void space with the surface of the article  10 . The retaining surface  28  should also be capable of maintaining the at least partial vacuum in the vacuum chamber  40  without allowing ambient air to leak into the vacuum chamber by creating a continuous contact perimeter (shown on  FIG.  4    as  38 ) between the retaining surface  28  and the surface  16  of the article  10 . The configuration of the retaining surface  28  can have depressions or raised areas therein (provided that these do not allow air to leak in), and be concave, convex, substantially planar, or be any combination of the foregoing. Of course, any convexity in the retaining surface  28  must still allow for the creation of the void space. In some embodiments, particularly those in which it is desired for the vacuum holder  20  to serve as a platform to support an article  10 , at least a portion of the retaining surface  28  may be substantially planar. For example, if the article  10  is a bottle that is to be held on the bottom  14  and supported by the retaining surface  28 , and the bottom  14  of the article has an inward dome or concavity therein, then the concavity on the bottom of the bottle  10  will provide a suitable void space  40  even if (at least a portion of) the retaining surface  28  is substantially planar. When it is said that at least a portion of the retaining surface  28  is substantially planar, it may, but need not be completely planar. 
     It is also desirable to form a seal between the surface of an article to be held and the retaining surface  28  of the vacuum holder  20 , particularly at the continuous contact perimeter  38 , in order to maintain an at least partial vacuum in the vacuum chamber  40 . As shown in  FIGS.  1 - 3   , this may be achieved by placing a gasket  30  between the surface of the article and the outer surface  22 A of the holder body  22 . The portion of the surface of the article  10  being held (for example, the bottom of the article  14 ) may be held adjacent to the outer surface  22 A of the main body  22  with the gasket  30  between the surface of the article and the outer surface  22 A of the main body  22 . The gasket  30  can be any suitable element that is compliant (that is, conformable) and/or compressible so that it assists in forming a substantially airtight seal between the portion of the surface of the article being held and the retaining surface  28  of the vacuum holder  20 . The gasket  30  can be made of any suitable at least partially air impervious material that is sufficiently impervious to air so as to allow the formation and maintenance of the vacuum for a sufficient period of time. Suitable materials include, but are not limited to polyurethane rubber, nitrile butadiene rubber (NBR), ethylene propylene diene monomer (EPDM) rubber, neoprene (polychloroprene) rubber, silicone rubber, processed natural gum rubber, or a thermoplastic resin with extremely low hardness that is formed into a flexible and durable elastomeric material for air or other gas leak testing instruments such as Cosmo SUPER GEL™ obtained from Cosmo Instruments Co., Ltd., Tokyo, Japan. In the embodiment shown in  FIGS.  1 - 3   , the gasket  30  is a flat rectangular piece of material that has a uniform thickness. The size, shape, thickness profile and material properties of the gasket  30  can be altered to allow an even broader range of articles to be held. These changes may also enable other transformation extremes like sending the vacuum holder  20  through heat tunnels, steam tunnels, chemical exposure, etc. 
     In other embodiments, the gasket  30  can be eliminated, and a top layer of the main body  22  can be provided with properties that allow it to serve the function that would have been performed by the gasket. This can be done, for example, by making the main body  22  using a dual shot injection mold where the top layer of the main body  22  is made of a compressible material such as a thermoplastic elastomer like ExxonMobil&#39;s SANTOPRENE™ or other synthetic rubbers including those among the examples mentioned earlier, and the remainder of the main body  22  is made of a more rigid material. Thus, the retaining surface  28  can be formed by the outer surface  22 A of the main body  22  or the gasket  30 . 
       FIG.  5    shows that, in other cases, at least a portion of the retaining surface  28  may have a concavity (or “recess”)  42  therein. The concavity (or recess)  42  may be of any suitable configuration. For example, if the article  10  is a bottle that is to be held on the bottom  14  and supported by the retaining surface  28 , and the bottom  14  of the article  10  is substantially planar, at least a portion of the retaining surface  28  may have a concavity  42  therein to provide the vacuum chamber  40 . Alternatively, the outer surface  22 A of the main body  22  may be substantially planar, and a gasket with a concavity or void therein may be placed between the outer surface  22 A and the surface of the article to provide the vacuum chamber. 
     In other cases, as shown in  FIG.  6   , it may be desirable to provide the vacuum holder  20  or main body  22  with other features, or to provide the retaining surface  28  with configurations other than a substantially planar configuration, or a configuration with a concavity therein. Such other cases may occur if the surface of the article  10  to be held has a configuration in which gaps are formed that would prevent the formation of a sealed void space (that is, a continuous contact perimeter) with a retaining surface  28  that has either a substantially planar configuration, or a configuration with a concavity therein. For example, such a situation would be present if the article  10  is a bottle that is to be held on the bottom and supported by the retaining surface, and the bottom of the article has a central concavity therein which is surrounded by a plurality of spaced apart feet (such as in disposable plastic water bottles currently in wide use), sometimes referred to as “petals” in the case of blown bottles. Air would tend to leak in through the spaces between the feet. In such cases, the retaining surface  28 , such as the surface of the gasket  30  can be configured (e.g., by molding, thickness profiling or other methods) to more closely conform to the configuration of the bottom surface  14  (or other surface to be held) of the article  10 . In some cases as shown in  FIG.  6   , the gasket  30  can extend along at least a portion of the sides of the article  10  to form a skirt gasket seal. In such cases, it may not be necessary for any portions of the gasket  30  to be positioned between the bottom  14  of the article  10  and the main body  22 . Of course, in other embodiments, the gasket  30  may form a seal along portions of the sides of the article, and also comprise a portion that is positioned between the bottom  14  of the article  10  and the main body  22 . 
       FIGS.  6 A- 6 C  show another embodiment of a gasket  30  that can be used for holding such articles  10 . In the embodiment shown in  FIGS.  6 A- 6 C , rather than comprising a flat continuous piece of material, or a piece of material having a surface that is configured to conform to the bottom surface of the article  10 , the gasket  30  has an opening or hole (or aperture)  36  therein. The gasket  30  comprises an elastically extensible material that has a first (or initial) unextended configuration and dimensions and a second extended configuration and dimensions. The elastically extensible gasket material is capable of extension in the plane of the surface of the gasket by application of tensile forces to the same. After the tensile forces are removed from the material (the material is relaxed), it retracts back to a third (or relaxed) configuration and dimensions. The gasket material retracts at least part of the way to its initial unextended configuration and dimensions. If the gasket material retracts back to its initial unextended configuration and dimensions, then its relaxed configuration and dimensions will be the same as its first configuration and dimensions. If the gasket material only retracts part of the way to its initial configuration, then its third configuration and dimensions will be between its first and second configuration and dimensions. 
     This gasket  30 , in its unextended configuration, has an opening  36  with a perimeter having a length (measured along the perimeter) that is smaller than the dimensions of the perimeter of the base  18  of the article  10 . For the purpose of describing this embodiment, the term “base of the article”, refers to the portion of the article  10  that is positioned adjacent to the surface of the vacuum holder. The base  18  of the article  10  therefore may, but need not, be at the bottom  14  of the article. In addition, the “base” of the article  10  may also include portions of the article (such as on the sides of the article as shown in  FIG.  6 C ) that are adjacent to the portion of the article that is in contact with the vacuum holder (the “contact surface”). That may occur if the gasket  30  contacts portions of the article that are adjacent to, but displaced from, the contact surface. The opening  36  in the gasket  30  can be of any suitable shape including, but not limited to circular and oval. (Thus, the length of the perimeter of a circular opening will be that of its circumference.) The opening  36  can be of any suitable size and shape, provided that the perimeter of the opening  36  is smaller than the perimeter of the base  18  of the article  10  after the gasket  30  is stretched and relaxed. This will allow the gasket  30  to fit snugly around the base  18  of the article  10 . The outer dimensions of the gasket  30  (that is, the outer perimeter of the gasket  30 ) will typically be larger than base  18  of the article  10 . 
     This embodiment operates as follows. The extensible gasket  30  is extended so that the opening  36  is larger than the base  18  of the article  10 . The article  10  is then placed through the opening  36  in the gasket  30  and on top of the retaining surface  28  of the vacuum holder  20 . The gasket  30  is then allowed to retract so that the opening  36  in the gasket  30  fits snugly around the base  18  of the article  10 . As shown in  FIG.  6 C , this causes the portion of the gasket  30  adjacent to the opening  36  to form a skirt around the base  18  of the article  10 . More specifically, the portion of the gasket adjacent to the opening  36  is disposed toward the end of the article opposite the base (upward in this drawing figure) and out of the plane of the remainder of the gasket to form a lip or rim  86 . 
     Various alternative embodiments of the extensible gasket  30  are also possible. For example,  FIG.  6 D  shows an extensible gasket  30  with a truncated cone shape or volcano-shaped configuration. In such a case, the smaller opening or mouth of the volcano will be facing upward so that it faces away from the retaining surface  28  of the vacuum holder  20 . The volcano-shaped gasket configuration has been found to be beneficial in ensuring that the extensible gasket  30  will assume the configuration shown in  FIG.  6 C  after the gasket is relaxed and makes contact with the base  18  of the article. Without the volcano shape, the gasket can sometimes buckle upward resulting in an upside down version of the shape of the gasket shown in  FIG.  6 C , which may not form an adequate seal with the surface of the article  10 . 
     Ideally, the elastically extensible gasket  30  is made of a material that has certain properties. These include: (1) the ability to undergo a relatively high degree of stretching or strain without breaking; (2) the ability to be repeatedly stretched over a large number of extension/relaxation cycles with minimal loss of its modulus of elasticity; and (3) exhibits low stress at various strains up to the strain at which breakage occurs. 
     The term “extensible”, as used herein, means the ability to stretch or elongate, without rupture or breakage, to at least 50% strain, for example, as described below in the Hysteresis Test. The terms “elastic,” “elastomeric,” and “elastically extensible” mean the ability of a material to stretch by at least 50% strain without rupture or breakage at a given load, and upon release of the load the elastic material or component exhibits at least 75% recovery (i.e., has less than 25% set). For example, an elastic material that has an initial length of 25.4 mm can stretch to at least 38.1 mm (50% strain) and, upon removal of the force, retract to a length of 30.5 mm (i.e., have a set of 5.1 mm or 20%). Stretch, sometimes referred to as strain, percent strain, engineering strain, draw ratio, or elongation, along with % recovery and % set may each be determined according to the Hysteresis Test described below. 
     With respect to the property of strain without breaking, the gasket  30  may be capable of surviving a strain of at least about 50% to at least about 1,100%, or more (or any 100 percent increment therebetween—e.g., 100%, 200%, 300%, 400%, 500%, etc.) without breaking. It is understood, however, that the gasket  30  may experience strain of less than 50% in use (e.g., as low as about 20%) to load and hold articles of the same size and cross-sectional shape. It is believed that a strain of as low as about 20% to about 100% may be sufficient to load articles having many different cross-sectional shapes (circle, square, oval, hexagon, etc.) so long as the base  18  of the articles  10  have substantially the same perimeter and aspect ratio. If it is desired to use the extensible gasket with a range of articles that vary in the size of their perimeter, higher amounts of strain (e.g., 200%, 300%, 400%, 500%, etc.) may be desirable. 
     It is desirable for the gasket to be capable of such strain through multiple cycles as described below. When it is said that it is desirable for the gasket to undergo “insubstantial loss” (or synonymously “minimal loss”) of its modulus of elasticity, this means that the gasket does not: (a) sag to such a degree that it interferes forming a seal with the desired part of the article; and/or (b) fail to retract sufficiently to form an air tight seal with the article. 
     With respect to the property of being able to be repeatedly stretched over a large number of extension/relaxation cycles with minimal loss of its modulus of elasticity, it may be desirable for the gasket to be capable of undergoing at least 1,000 cycles up to 100,000 cycles, or more (or any 10,000 cycle increments therebetween). For example, it may be desirable for the extensible gasket material to be capable of undergoing up to 1,000, 5,000, 10,000, 50,000, or more cycles (or any increment of 1,000 cycles between these numbers) while maintaining its properties sufficiently to perform its intended function (such as its modulus of elasticity). For example, one material, after being extended to a strain of 400% and relaxed to a strain of 100%, and being cycled between such strains up to 100,000 times, may exhibit a decrease of modulus of elasticity of only about 40% or less at a strain of up to 1,000%, or a decrease of modulus of elasticity of only about 30% or less at strain of up to 800%, or a decrease of modulus of elasticity of only about 25% or less at strain of up to 400%, or a decrease of modulus of elasticity of only about 10% or less at a strain of up to 200%. 
     With respect to the property of exhibiting low stress at various strains up to the strain at which breakage occurs, this refers the ease with which the gasket  30  can be stretched to ensure that the opening  36  is larger than the base  18  of the article  10 . A low stress, thus, is indicative of a gasket that can be stretched with ease. It may be desirable that the gasket material exhibit a stress of less than 0.5 MPa, 0.4 Mpa, 0.3 Mpa, 0.2 MPa, 0.1 MPa or 0.05 MPa at a strain of up to about 200% and/or the gasket material exhibit a stress of less than less than 0.5 MPa, 0.4 Mpa, 0.3 Mpa, 0.2 MPa, or 0.1 MPa at a strain of up to about 500% and/or the gasket material exhibit a stress of less than 0.5 MPa at a strain of up to about 1,000%. It may also be desirable that the gasket material exhibit a minimal level of stress at low strain so that the gasket  30  will not sag too much. For example, it may be desirable that the gasket material exhibit a stress of greater than or equal to about 0.01 MPa at strains equal to 10% or greater. 
       FIG.  12    shows several elastically extensible materials that have been proposed for use an elastically extensible gasket. Comparative Ex. 1 is 25A Duro polyurethane. Comparative Ex. 2 is latex rubber. While it is believed that the materials described in Comparative Exs. 1 and 2 can be used, they are less preferred. Suitable materials may include thermoplastic elastomers. 
     One suitable material for such a gasket  30  is Cosmo SUPER GEL™. Cosmo SUPER GEL™ has an Asker C hardness from 0 to 30 degrees. Cosmo SUPER GEL™ is very useful for this purpose because it is highly elastically extensible, extremely durable, and conforms closely to the configuration of the article. As shown in  FIG.  12   , Cosmo SUPER GEL™ is capable of undergoing a strain of over 1,100% before it reaches its necking point at a stress of slightly over 0.7 MPa. The necking point of a material is the point where a material begins to permanently deform, such that it begins to lose its elasticity, among other properties.  FIG.  12    also shows that Cosmo SUPER GEL™ is capable of undergoing a strain of over 1,200% before failure. 
     Another material that may be suitable for use as an extensible gasket which is shown in  FIG.  12    is McMaster Carr #1782T54 thermoplastic elastomer available from the McMaster-Carr Supply Company, Elmhurst, Ill., U.S.A. 
     The extensible gasket  30  can be of any suitable thickness provided that it is able to conform closely to the article and form a seal with the article. A suitable range of thickness is between about 2 mm and about 8 mm. In some cases, the extensible gasket  30  can be about 5 mm thick. 
     The extensible gasket  30  can be extended and retracted in any suitable manner and by any suitable stretching or expanding mechanism (or simply “expanding mechanism”). It should be understood that even though it may not always be shown in these embodiments, at least one of the retaining surface and the surface of the article is configured to provide a void space between the surface of the article and the retaining surface. 
       FIGS.  6 A and  6 B  show one expanding mechanism  90  for extending and retracting the extensible gasket  30 . In this embodiment, the expanding mechanism  90  comprises part of the vacuum holder  20 . Such a mechanism  90  can take many possible different configurations. In the embodiment shown, the expanding mechanism  90  comprises a plurality of pistons  92  (shown extended from piston housings  94  in  FIG.  6 B ) with grippers or clamps  96  joined thereto. The pistons  92  can extend from any suitable portion of the vacuum holder. In the embodiment shown, there are four pistons  92 , and each piston  92  extends from a piston housing  94  at one of the corners  22 D of the main body  22  of the vacuum holder  20 . 
     As shown in  FIG.  6 B , the pistons  92  are movable diagonally outwardly away from the opening  36  in the gasket  30  to increase the size of the opening  36  so that it is larger than the base  18  of the article  10 . After the base  18  of the article  10  is placed within the opening  36  (and the base of the article is in contact with the retaining surface  28  of the vacuum holder  20 ), the pistons  92  allow the gasket  30  to retract, and the portions of the gasket  30  adjacent to the opening  36  fit closely around the base  18  of the article  10 . In embodiments in which the gasket  30  has an opening  36 , the retaining surface  28  that the surface of the base of the article  10  is placed in contact will typically be the outer surface  22 A of the main body  22  or top plate  32  of the vacuum holder  20  (rather than the gasket  30 ). The grippers  96  in this embodiment may continue to grasp the gasket  30  at all times, including after the vacuum is drawn. Since the grippers  96  do not release the gasket  30 , this avoids the challenge of the grippers  96  having to reacquire (or regrip) the gasket  30  when it is time to extend the gasket again. 
     In this embodiment, if the corners of the gasket  30  remain slightly elevated above the retaining surface after stretching, it may be desirable to provide a placement or “positioning” mechanism that pushes the gasket  30  against the top surface of the vacuum holder  20  before a vacuum is drawn. Such a positioning mechanism can be part of a mechanism (such as at an article loading station) that is separate from the vacuum holder  20 . One non-limiting embodiment of such a positioning mechanism  110  is shown and described in  FIGS.  6 E,  6 F, and  6 H  below. Of course, in other embodiments, such a positioning mechanism may comprise part of the vacuum holder  20 . 
       FIGS.  6 E- 6 H  show another expanding mechanism  100  for extending and retracting the gasket  30 . This expanding mechanism  100  is separate from the vacuum holder  20 , and works in conjunction with (that is, as part of a combination with) a vacuum holder  20 . In the embodiment shown, the vacuum holder  20  is in the form of a vehicle that travels around a conveyor  72  in the form of a track system. Such a track system is described in greater detail below. As shown in these figures, this expanding mechanism  100  can be located at a station along the track system. For example, the expanding mechanism  100  can be located at a station for loading vehicles with the article to be transported. Such a mechanism  100  can take many possible different configurations. 
     In the embodiment shown, this expanding mechanism  100  comprises four movable gripping mechanisms  102  for gripping the four corners of the gasket to extend the gasket. (The gasket is not shown in  FIGS.  6 E- 6 H , but may be the same as that shown in  FIGS.  6 A- 6 D ). The movable gripping mechanisms  102  comprise a gripper track  104  along which grippers or clamps  106  are slidably movable. The movable gripping mechanisms  102  are movable diagonally outwardly away from the opening  36  in the gasket  30  to increase the size of the opening  36  so that it is larger than the base  18  of the article  10 . One of the gripping mechanisms  102  is shown in greater detail in  FIG.  6 G . The clamps  106  in the drawing are part of clamp assemblies  112  that may be referred to as “bobbins” (not because they hold thread, but because they may have components that resemble the shape of a bobbin). The top part of these bobbins  112 , the clamps  106 , are permanently attached to the gasket corners (that is, until the gasket is replaced). The bottom part  114  of the bobbin  112  is shaped like two spools stacked one on top of the other. The spools define an upper spool groove  116  and a lower spool groove  118 . The upper spool groove  116  slips into a slot  122  in the corner of the vacuum holder  20  top plate  32 . When it is time to expand the gasket  30 , a sled  124  slides into the lower spool groove  118  at the bottom of the bobbin  112  and carries the bobbin away from the holder top plate slot  122  outwardly away from the gasket opening  36  (not shown). When the gasket  30  is retracted, the sled  124  carries the bobbin  112  back towards the center and “drops it off” back in the slot  122  at the corner of the holder top plate  32 . With the sleds  124  in the retracted position, and the bobbins  112  in the grooves in the top plate  32 , it is still possible for the vacuum holder  20  to pass freely over the sleds  124  without interference. 
     As in the case of the prior embodiment, after the base  18  of the article  10  is placed within the opening  36  (and the base of the article  10  is in contact with the retaining surface  28  of the vacuum holder  20 ), the gripping mechanisms  102  allow the gasket  30  to retract and the opening  36  in the same to fit closely around the base  18  of the article  10 . 
     This embodiment may also include a positioning mechanism  110  to push at least portions of the gasket  30  flat against the retaining surface  28  of the vacuum holder  20 . This may be desirable before a vacuum is drawn to ensure an airtight seal is formed. In the embodiment shown, the positioning mechanism comprises a pair of arms  110  that push the gasket  30  against the top surface of the vacuum holder  20 . 
     It should be understood that while the embodiments of the expanding mechanisms described herein grip the corners of the gasket  30  in order to extend the same, the invention is not limited to such embodiments. In other embodiments, any suitable portions of the gasket  30  (such as the sides of the gasket  30 ) can be gripped and extended by any suitable mechanism. 
       FIGS.  6 I- 6 M  show still another expanding mechanism  130  for extending and retracting an extensible gasket  30 . In this embodiment, the expanding mechanism  130  comprises part of the vacuum holder  20 . Such a mechanism  130  can take many possible different configurations. In the embodiment shown, the expanding mechanism  130  comprises a frame  132  with a generally circular configuration. The frame  132  comprises retaining members for holding the edge portions of the extensible gasket  30 . The retaining members can be in any suitable number and configuration. The only requirements are that the retaining members be capable of holding the edge portions of the extensible gasket  30  therebetween, and that air tight chambers are formed as described below. 
     As shown in  FIGS.  6 I and  6 J , in this embodiment, the retaining members comprising a ring-shaped upper holding member  134 , a middle retaining component  136 , and a base portion  138 . The upper holding member  134 , middle retaining component  136 , and base portion  138  may comprise portions of the frame  132 . The middle retaining component  136  shown in these figures has a sideways oriented U-shaped cross-section where a gap G (also shown at the tip of arrow  144  in  FIGS.  6 K and  6 L ) forms the center of the U, and legs of the U are formed by the upper and lower retaining portions  136 A and  136 B, respectively. The ring-shaped upper holding member  134  is positioned on top of the upper retaining portion  136 A for holding portions of the gasket. The lower retaining portion  136 B of the middle retaining component  136  is positioned on top of the ring-shaped raised perimeter portion  138 A of the base portion  138  for holding other portions of the gasket  30 . 
     The expanding member  130  also comprises a gasket expansion chamber vacuum port  140  for drawing a vacuum to stretch the gasket  30 , and an article vacuum chamber port  142  for drawing a vacuum to hold an article to the retaining surface  28 . As shown in  FIG.  6 J , the gasket expansion chamber vacuum port (or simply “gasket vacuum port”)  140  is in fluid (or air) communication with the gap G between the upper and lower retaining portions  136 A and  136 B of the middle retaining component  136 . This gap G forms at least part of the gasket expansion chamber  144 . The article vacuum chamber port  142  is in fluid (or air) communication with an article vacuum chamber  146  that is located adjacent the retaining surface  28  of this vacuum holder  20 . 
     The extensible gasket  30  is comprised of two layers comprising a first layer, shown as an upper layer  30 A and a second layer, shown as a lower layer  30 B. The layers  30 A and  30 B are joined together at the central part  30 C of the gasket which surrounds the opening  36 . The outer edge portions of the layers are not joined together outside of the central part  30 C of the gasket  30  so that they can be gripped by the retaining members of the vacuum holder. More specifically, the upper layer  30 A has an outer edge  30 A 1 . The upper layer  30 A also has an outer edge portion (or simply “outer portion”)  30 A 2  that is located between outer edge  30 A 1  of the upper layer  30 A and the central part  30 C of the gasket. The lower layer  30 B has an outer edge  30 B 1 . The lower layer  30 B also has an outer edge portion (or simply “outer portion”)  30 B 2  that is located between the outer edge  30 B 1  of the lower layer  30 B and central part  30 C of the gasket. The two-layered extensible gasket can be made in any suitable manner including, but not limited to lamination, and molding the two layers as one piece. 
     The gasket  30  is placed so that the outer portions  30 A 2  of the upper layer  30 A of the gasket  30  are positioned between the upper holding member  134  and the upper retaining portion  136 A of the middle retaining component  136 . The outer portions  30 B 2  of the lower layer  30 B of the gasket  30  are positioned between the lower retaining portion  136 B of the middle retaining component  136  and the raised perimeter portion  138 A of the base portion  138 . This spaces apart the outer portions  30 A 2  of the upper layer  30 A and the outer portions  30 B 2  of the lower layer  30 B of the gasket and creates a space for vacuum to be drawn therebetween. 
     The expanding mechanism  130  shown in  FIGS.  6 I- 6 M  is particularly suitable for use with articles having a non-flat surface by which they are to be held (e.g., non-flat bottom bottles). The elastic gasket  30  engages with the sides of the article above the base of the article. The elastic gasket  30  can engage with the sides of the article any suitable distance above the base of the article (e.g., from about 5 mm to about 20 mm). In the case of plastic bottles where the sides of the bottle are often smoother than the bottoms, this may provide the additional advantage of creating a better seal with the gasket. The expanding mechanism  130  shown in  FIGS.  6 I- 6 M  is also particularly advantageous because it requires no moving parts. 
     In operation, the expanding mechanism  130  shown in  FIGS.  6 I- 6 M  works as follows.  FIG.  6 K  shows the expanding mechanism  130  without any tension placed on the gasket  30 . In a first step, the aperture  36  must be enlarged. To enlarge the aperture  36 , the air is evacuated from the gasket expansion chamber  144  by drawing a vacuum through the gasket vacuum port  140 . The vacuum draws portions of the gasket  30  into the previously-described gap, which makes the aperture  36  larger.  FIG.  6 L  shows the configuration and size of (one embodiment of) the aperture  36  after tension is exerted on the gasket  30  radially outward in the direction of the arrows to partially extend the gasket  30 .  FIG.  6 M  shows the configuration and size of (one embodiment of) the aperture  36  after tension is exerted on the gasket  30  to fully extend the gasket  30 . 
     Next, the base of the article is placed in contact with retaining surface  28 , which comprises part of the base  138  of the expanding mechanism  130 . The base of the article is placed within the aperture  36  of the gasket  30 . The vacuum in the gasket expansion chamber  144  between the upper and lower retaining members  136 A and  136 B is then released so that the gasket  30  retracts and the portions of the gasket around the aperture  36  fit snugly against the sides of the article. When the vacuum is released, the outer portions of the gasket  30  will return to a configuration similar to that shown in  FIG.  6 K , and the aperture  36  will take the configuration of the sides of the article that is being held. A vacuum is then drawn through the article vacuum chamber port  142  to draw a vacuum on the base of the article with the article vacuum chamber  146 . This vacuum can be retained using a Schrader valve such used in the prior embodiments. 
     The present invention also relates to the combination of a vacuum holder  20  and an article  10 . In one embodiment, the combination of a vacuum holder  20  and article  10  comprises an article  10  having a surface with a concavity therein which is held against the retaining surface  28  of the vacuum holder  20  when the vacuum holder is in its activated configuration, and the concavity in the surface of the article provides the space (vacuum chamber  40 ) between the surface of an article and the retaining surface  28 . In one version of this embodiment, the combination comprises a vacuum holder  20  and an article  10  wherein the article  10  (such as a bottle) has a top optionally provided with an opening and a bottom, and the concavity is in the bottom  14  of the article. In another embodiment, the combination of a vacuum holder  20  and an article  10  is one in which the vacuum holder  20  has a retaining surface  28  with a concavity therein. In this case, the article  10  is held against the retaining surface  28  of the vacuum holder  20  when the vacuum holder  20  is in its activated configuration, and the concavity in the retaining surface  28  of the vacuum holder  20  provides the space for the vacuum chamber  40  between the surface of the article and the retaining surface  28 . 
     The main body  22  of the vacuum holder  20  may be formed of a solid block of material or from one or more pieces of material. Alternatively, the main body  22  may have one or more hollowed out and/or internal portions (or compartments) therein in order to save material and/or weight. The main body  22  can be made from any suitable material(s). Suitable materials include, but are not limited to metals (e.g., stainless steel or aluminum), plastic including thermoplastic or thermoset polymer resins, and composite materials. The main body  22  can be made by any suitable process including, but not limited to injection molding in the case of plastic materials. The main body, or portions thereof, may be produced from a single or multiple kinds of suitable materials by any known additive, subtractive, assembly or combination of manufacturing methods. Materials and manufacturing method selection may be similar, identical, vary or differ between or within portions of the main body  22 . 
     The vacuum holder  20  may be subject to many different uses and may be used in many different processes including, but not limited to production processes which include those in which the article is a container in a filling and capping operation. The vacuum holder  20  may not only be subject to the rough handling of a production line but, additionally, as product is invariably spilled onto the vacuum holder  20  during container filling and capping operations, the vacuum holder  20  may need to be washed. Depending on the nature of the product(s) introduced into the container, washing may require use of hot water and detergents. Thus, it may be desirable for the main body  22  to be impervious to repeated washings with hot water, steam and detergents. 
     The opposed surface  22 B (as shown in  FIGS.  1  and  2   ), which in some cases may form the bottom of the main body  22 , may have optional extensions that form “runners”  44  joined thereto and extending therefrom. There can be any suitable number of runners (e.g., two or more). In the embodiment shown in  FIGS.  1  and  2   , there are four runners in which one runner  44  is located adjacent each corner of the bottom of the main body  22 . These runners  44  are useful if the main body  22  is intended to move on a conveyor by sliding the main body  22  on its bottom surface  22 B. The runners  44  may be used to stabilize the main body  22  and/or provide other benefits. The runners  44  can be made of the same material as the remainder of the main body  22 . In other embodiments, any portion of the bottom of the main body in contact with the conveyor including the entire bottom surface, or the runners, can be made of a low friction material such as TEFLON® impregnated or coated plastic. Alternatively, a low friction material could be applied to (e.g., coated on) such surfaces. 
     In other embodiments, the friction forces can be reduced by providing wheels, bearings, or other rolling elements on the bottom surface  22 B of the main body  22 , or on any optional runners  44  thereon.  FIG.  7    shows one non-limiting embodiment of a vacuum holder  20  that is provided with wheels  46  on the bottom surface  22 B of the main body  22  to facilitate movement of the vacuum holder  20  in the machine direction (MD). The vacuum holder  20  may be provided with any suitable number of wheels  46 . Typically, there will be at least two wheels, alternatively at least four wheels  46 . In some cases, there may be at least three wheels on each side of the longitudinal centerline of the vacuum holder  20  so that the vehicle can smoothly skip over any breaks in the track surface (such as where pieces of track are joined together). In the particular embodiment shown, the vacuum holder  20  has eight wheels  46  that are vertically oriented in the drawing. The wheels  46  can be joined to the interior or exterior of the main body  22 . In the embodiment shown, the wheels  46  are joined inboard of the exterior of the main body  22  in both the machine direction and cross machine direction (CD). More specifically, the wheels  46  are located in recesses  48  on the bottom surface  22 B of the main body  22 . Any suitable portion of the wheels  46  may be located within the recesses. In the embodiment shown, the wheels  46  are almost entirely within the recesses, except for a portion that is about 10% of the height of the wheels which extends outward from the recesses. Four of the wheels  46  are located adjacent the corners on the bottom surface  22 B of the main body  22 . The other four wheels  46  are located further inward toward the center of the bottom surface  22 B of the main body  22 . The wheels  46  can allow the vacuum holder  20  to roll on top of the rails of a track. 
     In the embodiment shown in  FIG.  7   , the vacuum holder  20  is joined to a component  54  comprising a motive mechanism in order to form a vehicle. The motive mechanism can comprise any suitable type of mechanism. In the embodiment shown, the motive mechanism comprises a magnet that cooperates with a magnetic track system to propel the vehicle along the track system using electromagnetic force. The component  54  comprising the motive mechanism is joined to the bottom surface  22 B of the main body  22  of the vacuum holder  20  by a septum  58  that will lie between the sides of the rails of a track. The septum and/or the component  54  comprising a motive mechanism can have wheels thereon that are horizontally oriented to facilitate movement of the vehicle along the sides of the rails of a track. In the embodiment shown, there are four wheels on the component  54  comprising a motive mechanism that are designated  46 A, and two (horizontally-oriented) wheels on the septum  58  that are designated  46 B. 
     The vacuum holder  20  may also comprise an optional top plate  32  joined to the outer surface  22 A of the main body  22 . The term “joined to”, as used throughout this specification, encompasses configurations in which an element is directly secured to another element by affixing the element directly to the other element; configurations in which the element is indirectly secured to the other element by affixing the element to intermediate member(s) which in turn are affixed to the other element; and configurations in which one element is integral with another element, i.e., one element is essentially part of the other element. 
     The main body  22  may comprise a fluid (such as air) passageway  26 , or have a fluid passageway associated therewith. The fluid passageway  26  may be located within (or on) the main body  22 . The fluid passageway  26  may be formed into the main body  22 , or it may be in the form of a separate conduit that runs inside or outside the main body  22 . The fluid passageway  26  may extend from the valve  24  to the vacuum port  50 . In the embodiment shown in  FIG.  2   , the fluid passageway  26  passes through at least a portion of the main body  22 . In the embodiment, the fluid passageway  26  is located entirely within the main body  22 . The fluid passageway  26  initially extends parallel to the longitudinal axis, A, of the valve (and parallel to the retaining surface  28 ). The fluid passageway  26  then turns (such as by making a right angle) and runs generally perpendicular to the retaining surface  28 . The fluid passageway  26  may pass through a hole in the gasket  30 , if present, and form an opening or port  50  at the retaining surface  28 . In other embodiments, the fluid passageway may be entirely outside the main body  22 . For example, the valve can be located in the main body  22 , and a flexible hose that acts as the fluid passageway  26  could be connected to a separate plate where the vacuum port is located. In embodiments comprising multiple ports (described below), the fluid passageway  26  could also be a plurality of flexible hoses that are each joined to one of the vacuum ports. 
     The port  50  may be flush with the retaining surface  28 , whether the retaining surface  28  is the outer surface  22 A of the main body  22 , the top plate  32 , or the outer surface of the gasket  30 . In other embodiments, the fluid passageway  26  may be part of a structure that forms a protuberance or protrusion  52  so that the port  50  extends outwardly from the retaining surface  28 . When the port  50  is described as being located “at” or “along” the retaining surface, it is intended to include embodiments in which the port  50  is flush with the retaining surface  28  (that is, the port is in the retaining surface) as well as those in which the port  50  is in the form of a protuberance that extends outwardly from the retaining surface  28 . Providing such a protuberance  52  may be useful in cases in which the portion of the surface of the article being held, such as the bottom  14  of the article  10  is flexible and would tend to be drawn in and collapse by the application of the vacuum. The protuberance  52  ensures that the surface of the article being held (e.g., the bottom of the article) does not collapse when a vacuum is drawn by spacing the retained surface of the article away from the retaining surface  28 . This maintains the void space between the retained surface of the article and the retaining surface  28 . The port  50  can be of any suitable configuration. In the embodiment shown, the port is in the form of a slit. 
     The valve  24  may be associated with, or joined to, any portion of the vacuum holder  20  such as the main body  22 , in any suitable manner. This includes that the valve  24  may be located on or in any surface of the main body  22 , including any side, the bottom, or even the top provided it does not interfere with holding the article or formation of the vacuum chamber  40 . The location of the valve  24  may influence the shape, pathway and orientation of the fluid passageway  26 . In the embodiment shown in  FIGS.  1 - 3   , the main body  22  may comprise a recess for the valve  24 . The recess for the valve  24  may be located on any suitable surface of the main body  22  including the outer surface  22 A, the opposing surface  22 B, and the sides  22 C. In other embodiments, the valve  24  need not be located in a recess, but instead joined to the main body  22 . For example, the valve  24  may be joined to the outside of the main body  22 . 
     The valve  24  can be any suitable valve that is capable of being repeatedly opened and closed, and while in the closed position is capable of maintaining an at least partial vacuum between the vacuum holder  20  and the surface of the article  10  that is held by the vacuum holder  20 . Example valves include: a Schrader valve, a check valve, a butterfly valve, and a Presta valve also known as a French valve. In some embodiments, the valve  24  is a check valve (that is, a “one way valve” that allows fluid, such as air, to flow through it in only one direction). The check valve, in the form of a ball valve or a ball-spring check valve, may be of a type that allows vacuum to be quickly drawn with an activating tool and then quickly sealed, thus allowing the vacuum holder  20  (and article  10  held thereby) to be untethered from a vacuum source. 
     In some embodiments, the valve  24  may be a Schrader valve. A Schrader valve is a well-known type of valve that is commonly used on car tires. However, the use of such a valve in the manner described herein is not believed to be known. The Schrader valve allows for the two-way flow of air and provides the convenient activating and sealing mechanism described above. The Schrader valve comprises an externally threaded hollow cylindrical (typically metal) tube having an axis and a pair of ends comprising a first end and a second end. In the center of the first end, a metal pin is oriented along the axis of the tube. The pin is normally in a spring-loaded closed position, and the pin can be pushed to open the valve. Air can be both removed and let back in with the same valve by activating the pin at the appropriate time. If desired, the valve housing can be modified to make it smaller. The valve  24  can be joined to the main body  22  and be in fluid (e.g., air) communication with the air passageway  26 . The pin for opening the valve is accessible from the side opposing the air passageway  26  associated with the holder. The main body  22  may be configured so that the valve  24  is either permanent or replaceable. 
     Numerous alternative embodiments of the valve  24  are possible. For example, in some embodiments, more than one valve can be used. For instance, one valve can be in fluid communication with the air passageway  26 , and be used to draw a vacuum, and another valve which is also in fluid communication with the air passageway  26  can be used to open the air passageway  26  to let air in so that a vacuum is no longer present. The two valves may be of the same type or may be different from each other. 
     The top plate  32  can be used for any suitable purpose including, but not limited to: covering any cavities that were formed in the main body  22  (for the purposes of weight reduction or material savings; or, to cover unneeded ports) and/or facilitating joining the vacuum holder  20  to another component. The top plate  32  may span, including the optional joining of, two or more vacuum holders, for example to make a tandem pair of vacuum holders that can move or convey as a unit. The two or more vacuum holders joined together by a top plate may be done so in a separable manner or in a more permanent arrangement, utilizing, for example, mechanical or chemical (e.g. adhesive) elements. An O-ring  34  may be provided to prevent air from leaking into the vacuum chamber  40 . The O-ring may be in any suitable location. In the embodiment shown in  FIG.  2   , the O-ring  34  is located between the top plate  32  and the outer surface  22 A of the main body  22 . In this embodiment, the O-ring  34  surrounds the base of the extension  52  of the main body in which the vertical portion of the passageway  26  is formed that leads to the port  50 . Positioning the O-ring  34  at this location prevents air from entering the vacuum chamber  40  through any gaps between the top plate  32  and the main body  22  and releasing the partial vacuum in the vacuum chamber  40 . 
     In other embodiments, as shown in  FIG.  4    (and the following embodiments), the vacuum holder  20  may comprise fewer elements than those described above. For instance, one or more of the top plate, gasket, and O-ring can be eliminated. For example, the top plate can be eliminated, and the gasket  30  can rest directly on the main body  22 . In other embodiments, the top plate, gasket, and O-ring can all be eliminated. 
     Numerous alternative embodiments of the vacuum holder  20  are possible. The vacuum holder  20  is shown in  FIG.  3    as supporting an article. The vacuum holder  20  is, however, not limited to supporting a single article. The vacuum holder  20  can be of a size and configuration suitable for holding any desired number of articles (e.g., two, three, four, or more articles). As shown in  FIG.  8   , the vacuum holder  20  can, thus, hold a plurality of articles. The vacuum holder  20  shown in  FIG.  8    has a retaining surface  28  and an air passageway  26  in the form of a manifold with branches leading to portions of the retaining surface  28  associated with each article  10 . 
     The vacuum holder  20  may, as shown in  FIG.  8    comprise more than one port  50 . The multiple ports  50  are in fluid communication with a fluid passageway  26 . The multiple ports  50  may connect to the same vacuum chamber  40  or to different vacuum chambers  40  associated with one or more articles  10 . In another example, a fluid passageway  26  may lead to three ports  50 , wherein there are two vacuum chambers  40 . One port  50  may be associated with one vacuum chamber and the other two ports  50  may be associated with a different vacuum chamber. To accommodate fluid communication with the multiple ports  50 , the fluid passageway  26  may comprise, for example, a more voluminous volume such as a cavern-like or reservoir-like volume; or, a branched passage structure. As described earlier, the retaining surface  28  may comprise a gasket  30 . The retaining surface  28  may also comprise multiple gaskets  30  each associated with at least one port and one vacuum chamber. In addition, for a vacuum holder  20  that comprises multiple N number of ports  50 , when, unneeded, at least one up to N−1 ports may be capped, plugged or covered for the purpose of preventing fluid communication between the environment and the fluid passageway  26 , especially when the fluid passageway is under at least a partial vacuum. 
     The vacuum holder  20  may, as shown in  FIG.  8   , include more than one fluid passageway  26  wherein each fluid passageway  26  connects to at least one valve  24  and at least one port  50 . 
     When the vacuum holder is in the untethered activated state, one to all of the fluid passageways  26  may be under vacuum. For multiple fluid passageways  26  which are under vacuum, they may all be at the same vacuum level, given normal manufacturing variations. Alternatively, two or more of the fluid passageways  26  may have different levels of vacuum when compared at least one other fluid passageway of the activated vacuum holder  20 . Example differences of vacuum between any two fluid passageways  26  include greater than or equal to 0.1 psi (0.7 kPa), alternatively 0.5 psi (3 kPa), and alternatively 1 psi (7 kPa). 
     The different activated fluid passageways  26  may be utilized to hold different articles, or to hold the same article at the same or multiple vacuum chambers  40 , or a combination of these scenarios. If at least one of the fluid passageways  26  is unneeded to maintain at least a partial vacuum when the vacuum holder  20  is activated, then the valves  24  associated with the unneeded fluid passageways  26  may be opened to release any vacuum present. Further, during vacuum charging of the vacuum holder  20 , the valves of the unneeded air passageways  26  are not open for the purpose of drawing a vacuum. 
     The vacuum holder  20  may be provided with one or more additional holding features  56  as shown in  FIG.  9    if it is desired to convey bottles with non-flat or convexly-rounded bottoms that would be unstable on a horizontal surface, or bottles with small bases that will easily tip. The one or more holding features may be in continual contact with the article, or they may be in the near vicinity of the article but only contact the article in certain situations such as during vehicle acceleration or deceleration force experienced by the article wherein the holding feature provides additional anti-tipping function when contacted. 
     As shown in  FIG.  4   , a vacuum source  60  will typically be used in conjunction with the vacuum holder  20 . The vacuum source  60  can be used to draw an at least partial vacuum in the void space or vacuum chamber  40  between the retaining surface  28  of the vacuum holder  20  and the surface of the article to be held. Any suitable type of vacuum source can be used. One suitable type of vacuum source  60  is a vacuum pump. The vacuum pump  60  can have a hose  62  joined thereto, and a tool  64  at the distal end of the hose  62  for fitting into or onto the valve  24 .  FIG.  10    shows an alternative type of vacuum source  60  in the form of a piston-type device. This piston-type device  60  comprises a housing  66  having a chamber  67  with a movable piston  68  therein. When the piston  68  slides as shown, a vacuum can be drawn at the opening  69  of the device  60 . 
     The vacuum holder  20  can be used for numerous different purposes. In some cases, the vacuum holder  20  can be used in a system  70  for holding and conveying articles. As shown in  FIG.  11   , one non-limiting embodiment of the system  70  comprises an article conveyor  72  that conveys at least one article  10  past at least one station  74  for performing an operation on the article. If there is more than one station, they can be designated by reference numbers  74 A,  74 B,  74 C, etc. If the system  70  is part of a bottle processing operation, the stations  74  may, for example, comprise a bottle filling station  74 A, a decorating (e.g., labeling) station  74 B, and a capping station  74 C. 
     The term “conveyor”, as used herein, refers to devices that move articles generally, and is not limited to conveyor belts. The conveyor  72  can be any suitable type of conveyor. Suitable types of conveyors include, but are not limited to: endless loop conveyors, which may be in the form of tracks, belts, chains, and the like, and magnetic servo car conveyors. 
     In one embodiment, the conveyor  72  may be physically-guided track, guided by fixed or limited movement floor tracks, side rails, etc., upon which one or more wheel-equipped vacuum holders  20  may travel, and be moved by an on-board motive mechanism such as a motor to drive at least one of the wheels. To supply the motor with energy, the vacuum holder may comprise an on-board storage battery or capacitor supplying at least part of the vacuum holder with power. The storage battery or capacitor can be recharged at any desired time and position, examples include during routine maintenance, downtime of the individual vacuum holder, vacuum activation or deactivation or at certain points of travel or temporary rest on the physically-guide track. Recharging may occur by physical conductor connection to a power-charging source, or may be accomplished inductively for a vacuum holder equipped with the proper induction receiver coil. Alternatively, the vacuum holder&#39;s battery may be periodically removed from the vacuum holder and replaced with a charged battery replacement. 
     In other embodiments, the conveyor  72  may be a linear synchronous motor system, such as the MAGNEMOVER® LITE intelligent conveyor system. The MAGNEMOVER® LITE intelligent conveyor system, and the components thereof, are described in U.S. Pat. Nos. 6,011,508; 6,101,952; 6,499,701; 6,578,495; 6,781,524; 6,917,136; 6,983,701; 7,448,327; 7,458,454; and 9,032,880. Such a conveyor utilizes carriers that are propelled by the principle of linear synchronous motor technology on a guideway, and electronics control the motion of the carriers. The carriers can be moved and accelerated individually irrespective of the propulsion system. In such a case, the vacuum holder  20  may either comprise a magnetic flux source or be joined to a vehicle comprising a magnetic flux source. If the vacuum holder  20  is joined to a vehicle comprising a magnetic flux source, in one embodiment as shown in  FIG.  7   , the vacuum holder  20  described herein can form a portion of a vehicle that moves on top of the guideways of such a conveyor system. In such case, the vacuum holder  20  can be joined at a septum portion  58  to a second portion  54  of the vehicle that is located below a guideway, wherein the second portion of the vehicle comprises the magnetic flux source. 
     The conveyor  72  may move (and, thus, move the vacuum holders  20  and articles  10 ) in a linear path; a curvilinear path such as a circular path; or in a path that comprises both linear portions and curvilinear portions. Non-limiting examples of the latter paths include: elliptical paths, race track configured paths ( FIG.  11   ), and other closed loop paths. The conveyor  20  may also have one or more side tracks joined thereto for diverting one or more vacuum holders  20  and/or articles  10  for any desired purpose. 
     The system and apparatus  70  shown in  FIG.  11    is described as a plan view. In this case, the retaining surfaces  28  of the vacuum holders  20  are oriented horizontally and the articles  10  rest on top of the vacuum holders  20 . However, the entire apparatus  70  can be reoriented so that the retaining surfaces  28  are vertical, in which case  FIG.  11    would be a side elevation view. In other embodiments, the system and apparatus  70  can be oriented in any configuration between horizontal and vertical. In addition, due to the strong holding force that can be exerted on the articles by the vacuum holders  20 , it is even possible for at least a portion of the apparatus to be oriented so that the retaining surfaces  28  of the vacuum holders  20  are oriented horizontally and the articles  10  are held upside down by the vacuum holders  20  with the retaining surface  28  facing downward. Of course, if the articles  10  are containers to be filled with liquids, the filling would likely take place in a conventional gravity filling orientation with the articles  10  resting on top of the vacuum holders  20 . 
     The vacuum source  60  for charging the vacuum holders  20  may be located at a vacuum station, designated generally by reference number  80 . There may be one or more vacuum stations  80  located at any suitable place(s) along the conveyor  72 . The individual vacuum stations can be labeled  80 A,  80 B, etc. Any suitable device/vacuum source  60  (such as those described above) that is capable of temporarily connecting to a vacuum holder  20  and drawing a vacuum may be located at the vacuum station  80 . The vacuum source  60  at the vacuum station  80  may comprise a vacuum pump having a hose one end of which is joined to the vacuum pump. A vacuum tool, such as a nozzle, can be joined to the other end of the hose, and the nozzle may have a quick connect coupling similar to a gas station tire pump so that after the vacuum is drawn, the valve on the vacuum holder  20  may be closed to retain the vacuum. 
     The system and apparatus may also comprise a vacuum release device that is located at a vacuum release station  82 . The vacuum release station  82  may be located any suitable place(s) along the conveyor  72  where it is desired to open a valve and let air into the void space  40  in order to release the article  10  from attachment to the vacuum holder  20 . The vacuum release device can be a device that is configured to only open a valve. In other cases, the vacuum release device can comprise part of a combined vacuum source and vacuum release device. For example, the vacuum source or other device at a vacuum station  80  can be configured to: draw a vacuum on the vacuum holder  20 ; close a valve to retain the vacuum; and, when it is desired to release the vacuum, open the valve on the vacuum holder  20  to release the vacuum. 
     In such a process, at least one article  10 , such as a bottle, is initially brought into contact with the retaining surface  28  of the vacuum holder  20  so that the surface of the article  10  to be held by the vacuum holder  20  is aligned with and in contact with the retaining surface  28  of the vacuum holder  20 . This can be done by moving the article  10 , the vacuum holder  20 , or both. This can be done manually, statically such as by a gravity feed chute with optional gate, or with a mechanical motion device. Suitable mechanical motion devices include, but are not limited to: independently actuatable automatic arms, pneumatic arms, robots, transfer wheel, and other mechanical moving elements. In the embodiment shown in  FIG.  11   , where the retaining surfaces  28  of the vacuum holders  20  are horizontally-oriented, the bottles  10  are placed onto the retaining surfaces  28  of the vacuum holders  20 . 
     Next, a vacuum tool “activates” the vacuum holder  20  and draws vacuum on the bottom of the bottle. Vacuum is applied to the holder with a “vacuum tool” (with a bottle in place) and then once the tool is removed the valve  24  maintains vacuum between the vacuum holder  20  and the surface of the article (e.g., the bottom of the bottle). The vacuum holder  20 , thus, has an activated configuration wherein the void space between the surface of the article  10  and the retaining surface  28  of the vacuum holder  20  has air evacuated therefrom to create an at least partial vacuum therein. The valve  24  can be closed to retain the vacuum and hold the surface of an article  10  against the retaining surface  28  of the vacuum holder  20 . The passageway  26  between the valve  24  and the retaining surface  28  will also be at (or near) the at least partial vacuum. The vacuum tool is removed (the vacuum holder  20  is, thus, untethered) and then the vacuum holder  20  and bottle  10  may be conveyed on the conveyor  72 . When it is desired to remove the article  10  from the vacuum holder  20  such as to send the article  10  to another step or operation in the process, the vacuum can be released by opening the valve  24  (or a separate valve) and allowing air to enter the vacuum chamber  40 . The vacuum holder  20  has an unactivated configuration when the vacuum is released. In the unactivated configuration, the pressure is atmospheric or ambient, and the air passageway between the valve and the retaining surface is at (or near) the ambient or atmospheric pressure. 
     The articles  10  may be conveyed without separating from the holder  20  (e.g., falling off a horizontally-oriented platform) at up to certain velocities and accelerations. For example, bottles capable of holding between 9 and 40 oz. (266 milliliters to 1.2 liters) of liquid do not fall off vacuum holders that form horizontal platforms at up to 2 m/s, or more, peak velocity and 2 m/s 2 , or more, acceleration. The vacuum holder  20  is also capable of maintaining a vacuum for an extended duration, which is well in excess of the period of time an article will typically remain on a conveyor in a manufacturing process. 
     The vacuum holders  20  may have an optional vacuum gauge joined thereto to verify that the vacuum level is not changing from a desired setpoint. Suitable setpoints may vary depending on the article being held. For example, a much lower partial vacuum is needed to hold and stabilize (during vehicle movement) a light article, such as a bottle cap, than is necessary to hold and stabilize a heavier article, such as large bottle filled with fluent material. For holding light articles, a partial vacuum of −1 psig (−7 kPa) may be suitable. For holding larger and/or heavier articles, the set point can range up to a partial vacuum of −13 psig (−90 kPa) or of −14 psig (−96 kPa), up to a perfect vacuum (−14.7 psig (−100 kPa)). The vacuum holder set point can be any amount of partial vacuum within these ranges (or greater than or equal to the following amounts) including, but not limited to: −2 psig (−14 kPa), −3 psig (−21 kPa), −4 psig (−28 kPa), −5 psig (−34 kPa), −6 psig (−41 kPa), −7 psig (−48 kPa), −8 psig (−55 kPa), −9 psig (−62 kPa), −10 psig (−69 kPa), −11 psig (−76 kPa), −12 psig (−83 kPa), or any range between any of the set points described herein. The statement “greater than or equal” conveys that an equal or increased (i.e. greater) vacuum is present with an activated configuration. For example, the statement “at least partial vacuum which is greater than or equal to −2 psig (−14 kPa) includes activated configuration partial vacuums of −3 psig (−21 kPa), −4 psig (−28 kPa), −5 psig (−34 kPa), −6 psig (−41 kPa), −7 psig (−48 kPa), −8 psig (−55 kPa), −9 psig (−62 kPa), −10 psig (−69 kPa), −11 psig (−76 kPa), −12 psig (−83 kPa), −13 psig (−90 kPa), or −14 psig (−96 kPa), up to a perfect vacuum (−14.7 psig (−100 kPa)). The vacuum holder  20  vacuum level can stay at setpoint for more than two weeks. It is believed that the Schrader valve is capable of holding a perfect vacuum. 
     The vacuum holder  20  can be provided with various additional optional features. The vacuum holder  20  vehicles (or “carriers”) may be provided with noise reducing bumpers in the event one vacuum holder carrier collides with another vacuum holder carrier, or with some other object. The vacuum holder  20  can be provided with a tracking device such as an RFID tag to identify when the vacuum holder passes a known position. The vacuum holder  20  can be provided with an on-board vacuum/pressure sensor which can measure the pressure in the void space  40  and visually or electronically communicate the same to a human observer, or to a device such as a part of a control system. 
     The optional vacuum gauge may be operably joined to sensor and/or communication means so that any decrease in the vacuum may result in a notification to any operator or operating system that the vacuum has decreased. This notification can be linked to any of the set points outlined above and may result in a subsequent operation to refresh the vacuum. This notification can be made by any known communication means including both wired and wireless communication means. This notification may result in the holder be routed to a portion of the path where the vacuum may be recharged or to an inspection and/or reject station where the integrity of the holder can be checked and/or corrected. 
     The system  70  may also be provided with various additional optional features. Other types of operations that can be performed on a container and/or its contents include: loading, dispensing, mixing, sealing, emptying, unloading, heating, cooling, pasteurizing, sterilizing, wrapping, rotating or inverting, printing, cutting, separating, pausing to allow mechanical settling or mechanical separation or chemical reaction, or etching. In addition, such operations may include one or more inspections, including any of the following: scanning, weighing, detecting the presence or orientation of a container, or other types of inspection. 
     The vacuum holder  20  can also be subjected to a cleaning or other operation. For example, the system  70  may provide a washing, brushing, or blow-off operation. Such a cleaning operation can be provided at any suitable location in the system. For example, after an article such as a bottle has all the desired operations performed thereon, and is unloaded from the vacuum holder  20 , and prior to loading the vacuum holder  20  with another article, a blow-through of the passageway  26  could be used to clean out the passageway  26  of any spilled contents. In another example, at unloading or loading, the pressure or dynamic back pressure of air passing through the passageway  26  could be measured to determine if the vacuum holder&#39;s passageway  26  has a partial or complete restriction (due to soiling debris). 
     The vacuum holder  20 , system, and method described herein may provide a number of advantages. It should be understood, however, that such advantages are not required to be present unless set forth in the appended claims. The vacuum holder  20 , system, and method are capable of holding and/or conveying articles of a wide variety of shapes and sizes. The vacuum holder  20  may, unlike pucks, provide nearly full exposure of the top and sides of articles since the article (such as a bottle) may be only held substantially from the bottom. As a result, all other surfaces are unobstructed so decorations such as labels, stickers, shrink sleeves, etc. can be applied to these surfaces while any opening in the top (or any side) is free for a filling operation. The vacuum holder  20  may also operate with no external connections being required to supply vacuum. The vacuum holder  20  is, therefore, “untethered” allowing it to move freely around a conveyor. 
     The vacuum holder  20  also has several advantages over suction cups. This vacuum holder  20  is suitable for adhering to surfaces having a variety of different curvatures and/or surface features. Suction cups typically have a certain diameter, and are not suitable for holding articles having dimensions smaller than their diameter. Suction cups create a void space that is fixed, and is defined by the dimensions of the suction cup. The vacuum holder, on the other hand, can accommodate variable void spaces, and can apply adjustable levels of vacuum. It is typically not possible to adjust the level of vacuum created by suction cups. Suction cups typically do not have a high level of structural rigidity, and if a suction cup is holding an article that is subject to acceleration, the force of the acceleration may cause the suction cup to lose its grip on the article. The vacuum holder  20  only requires the opening and closing of a valve to draw and release a vacuum, and does not require any manipulation of a suction cup or mechanism attached thereto. 
     TEST METHODS 
     1-1. Sample Preparation for Tensile and Hysteresis Tests 
     The direction in which the elastic material will stretch in its intended use is considered the primary stretch direction of the material. For standalone materials, where the primary stretch direction is not known, the direction in which the material has greatest extensibility is assumed to be the primary stretch direction. A set of rectilinear specimens at least 30 mm long in the primary stretch direction, and 25.4 mm wide (W) in the perpendicular direction is cut from the material. The width “W” can be within 10% of 25.4 mm. The three specimens are cut from the same portion of identical materials for each set. The basis weight of each material specimen is measured. If the difference in the elastic material specimen basis weight is more than 10% between highest and lowest basis weight samples for any set, then specimens are re-collected for that set from a different part of the material, or from fresh products. Each set is analyzed by the methods described below. For the Tensile Test and Hysteresis Test, the direction in which specimen has longer dimension is considered the specimen direction of stretching. 
     1-2. Specimen Weight and Basis Weight 
     Each specimen is weighed to within ±0.1 milligram using a digital balance. Specimen length and width are measured using digital Vernier calipers or equivalent to within ±0.1 mm. All testing is conducted at 22±2° C. and 50±10% relative humidity. Basis weight is calculated using equation below. 
               Basis   ⁢           ⁢   Weight   ⁢           ⁢     (     g     m   2       )       =       (     Weight   ⁢           ⁢   of   ⁢           ⁢   the   ⁢           ⁢   specimen   ⁢           ⁢   in   ⁢           ⁢   grams     )             (     Length   ⁢           ⁢   of   ⁢           ⁢   the   ⁢           ⁢   specimen   ⁢           ⁢   in   ⁢           ⁢   meter     )               (     Width   ⁢           ⁢   of   ⁢           ⁢   the   ⁢           ⁢   specimen   ⁢           ⁢   in   ⁢           ⁢   meter     )                   
1-3. Tensile Test Setup
 
     A suitable tensile tester interfaced with a computer such as MTS model Alliance RT/1 with TestWorks 4® software or equivalent is used. The tensile tester is located in a temperature-controlled room at 22° C.±2° C. and 50±10% relative humidity. The instrument is calibrated according to the manufacturer&#39;s instructions. The data acquisition rate is set to at least 50 Hertz. The grips used for the test are wider than the sample. Grips having 50.8 mm width may be used. The grips are air actuated grips designed to concentrate the entire gripping force along a single line perpendicular to the direction of testing stress having one flat surface and an opposing face from which protrudes a half round (radius=6 mm, e.g. part number: 56-163-827 from MTS Systems Corp.) or equivalent grips, to minimize slippage of the specimen. The load cell is selected so that the forces measured are between 10% and 90% of the capacity of the load cell used. The initial distance between the lines of gripping force (gauge length) is set at 25.4 mm. The load reading on the instrument is zeroed to account for the mass of the fixture and grips. 
     The specimen is mounted into the grips in a manner such that there is no slack and the load measured is between 0.00 N and 0.02 N. The specimen is mounted in the center of the grips, such that the specimen direction of stretching is parallel to the applied tensile stress. 
     1-4. Tensile Test 
     The instrument is set up and the specimen mounted as described in the Tensile Test Setup above. The tensile test is initiated and the specimen is extended at 254 mm/min, with a data acquisition rate of at least 50 Hertz, until the specimen breaks, typically 500-1500% strain. The % strain is calculated from the length between grip lines L, and initial gauge length, Lo, as illustrated in  FIG.  1   , using the following formula: 
     
       
         
           
             
               % 
               ⁢ 
               
                   
               
               ⁢ 
               Strain 
             
             = 
             
               
                 
                   ( 
                   
                     L 
                     - 
                     
                       L 
                       0 
                     
                   
                   ) 
                 
                 
                   L 
                   0 
                 
               
               × 
               100 
             
           
         
       
     
     Three specimens of each set are measured, and the arithmetic average of stress at 100% strain (MPa), stress at 200% strain (MPa), stress at break (also called Tensile Strength, MPa), and % Strain at break are recorded. % Strain at break is defined as the % Strain at peak force. 
     Stress in MPa is calculated as follows: Stress=[measured force]/[specimen cross-sectional area]. 
     Specimen cross-sectional area is calculated from specimen weight, Wt (g); before straining specimen width, W (mm); and density of the material, ρ (g/cm 3 ). Specimen cross-sectional area A 0  (mm 2 ) is given by formula: A 0 =[Wt×10 3 ]/[ρ×W]. 
     1-5. Hysteresis Test 
     The instrument is set up and the specimen mounted as described in the Tensile Test Setup section above. Data acquisition rate is set to at least 50 Hertz. 
     The Hysteresis Test method for material specimens involves the following steps (all strains are % strains): 
     (1) Strain the specimen to 50% strain at a constant crosshead speed of 25.4 cm per minute. 
     (2) Hold specimen at 50% strain for 30 seconds. 
     (3) Go to 0% strain at a constant crosshead speed of 25.4 cm per minute. 
     (4) Hold specimen for 1 minute at 0% strain. 
     (5) Pull the specimen to 0.05 N force and return to 0% strain with no hold time.
         The Specimen length at 0.05 force in step (5) is recorded and used to calculate the % set in the material as below.       

     % Set=((Length at 0.05 N force−Original Gauge length)/Original Gauge length))×100. 
     The dimensions and values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such dimension is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “90°” is intended to mean “about 90°”. 
     It should be understood that every maximum numerical limitation given throughout this specification includes every lower numerical limitation, as if such lower numerical limitations were expressly written herein. Every minimum numerical limitation given throughout this specification will include every higher numerical limitation, as if such higher numerical limitations were expressly written herein. Every numerical range given throughout this specification will include every narrower numerical range that falls within such broader numerical range, as if such narrower numerical ranges were all expressly written herein. 
     All documents cited in the Detailed Description of the Invention are, in relevant part, incorporated herein by reference; the citation of any document is not to be construed as an admission that it is prior art with respect to the present invention. To the extent that any meaning or definition of a term in this written document conflicts with any meaning or definition of the term in a document incorporated by reference, the meaning or definition assigned to the term in this written document shall govern. 
     While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.