Abstract:
A stopper ( 1, 100, 200 ) for sealing bottles ( 3 ), particularly for sealing bottles of wine for ageing, comprises:—a main body ( 2 ) shaped in such a way as to be removably housed in engagement in an aperture ( 3   a ) of the bottles,—a first surface ( 5 ) and a second surface ( 6 ) formed on the main body and facing, respectively, the outside and the inside of the bottles when en the main body is received in engagement in the aperture,—at least one passage ( 4 ) extending between the first and second surfaces and capable of making the inside of said bottles communicate with the environment outside the bottles,—a permeable element ( 16, 101, 201 ) which is impermeable to liquids and permeable to oxygen, the said permeable element being extended to seal the said passage in order to regulate the flow of oxygen between the inside and the outside of the bottle, and having an oxygen permeability, measured at 2O° C., in the range from 10 −5  to 10 −11  (Ncm 3 *cm/cm 2 *cm Hg *s).

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a stopper for sealing bottles, particularly for sealing bottles of wine for ageing, the stopper having the characteristics stated in the preamble of the principal claim. 
       TECHNOLOGICAL BACKGROUND 
       [0002]    In the technical field of bottling drinks, particularly wine, there is a known need to replace the conventional cork stoppers with synthetic stoppers made from polymer material. This need arises from specific economic factors, significant technical drawbacks associated with conventional stoppers, including the possibility that cork stoppers will release substances which can alter the flavour of the wine, and the ease with which bacteria and moulds can develop on the wine. 
         [0003]    To provide a positive response to this need, stoppers made from polymer material, usually expanded, have been developed, but these stoppers do not allow a controlled oxygen exchange between the inside and the outside of the bottle, and therefore they prevent a correct wine maturing process, while causing the well-known problems of oxidation or reduction of the wine in the bottle. This limitation is particularly serious for wines for ageing, usually red vintage wines, which require long maturing periods to obtain the flavour properties which characterize them. 
         [0004]    In an attempt to resolve this problem, a synthetic stopper has been developed which includes a passage for putting the inside of the bottle in communication with the outside, sealed by a membrane intended to selectively regulate the flow of oxygen through the passage, between the inside and the outside of the bottle. 
         [0005]    An example of this prior art is described in international patent application WO 02/055397, in which this membrane is inserted into a support sleeve inserted into the passage formed in the stopper. 
         [0006]    However, the results achieved with the stoppers described therein are not completely satisfactory in respect of the maturing of wines and consequent oxidation or reduction phenomena of the wine in the bottle. 
       DESCRIPTION OF THE INVENTION 
       [0007]    The problem tackled by the present invention is that of providing a stopper for sealing bottles, which is structurally and functionally designed to overcome the limitations described above with reference to the cited prior art. 
         [0008]    This problem is resolved by the invention by means of a stopper produced in accordance with the claims below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The characteristics and advantages of the invention will be made clearer by the detailed description of some preferred examples of embodiment thereof, illustrated, for the purposes of guidance and without restrictive intent, with reference to the attached drawings, in which: 
           [0010]      FIG. 1  is a schematic view, in longitudinal section, of a first example of a stopper made according to the present invention, 
           [0011]      FIG. 2  is a schematic view in longitudinal section and on an enlarged scale of a detail of the stopper of  FIG. 1 , 
           [0012]      FIG. 3  is a schematic view in longitudinal section of a second example of a stopper made according to the present invention, 
           [0013]      FIG. 4  is a schematic view in longitudinal section of a third example of a stopper made according to the present invention. 
       
    
    
     PREFERRED EMBODIMENTS OF THE INVENTION 
       [0014]    In  FIGS. 1 and 2 , the number  1  indicates the whole of a first example of a stopper, made according to the present invention, intended for sealing bottles of wine, particularly wine for ageing which requires a considerable period of maturing. 
         [0015]    The stopper  1  comprises a main body  2 , of generally cylindrical shape with rounded edges and having dimensions such as to allow it to be housed and engaged in an aperture  3   a  of a bottle  3  only partially indicated by broken lines in  FIG. 1 . 
         [0016]    The main body  2  is made from any polymer material having mechanical and sealing characteristics such that it is as impermeable as possible to liquids, gases and vapours such as expanded polyethylene, or polyolefin and styrene based copolymers, or elastomers in general. 
         [0017]    A passage  4  is formed in the main body  2  and extends along a longitudinal axis X of the body  2 , opening at its opposite ends which form a first surface  5  and a second surface  6 . When the stopper  1  is inserted into the bottle  3 , the first and second surfaces  5  and  6  are intended to face the outside environment in one case, and the inside of the bottle in the other case, thus forming an outer surface and an inner surface of the stopper  1 . Clearly, the stopper is of a two-way type; that is to say it can be inserted into the neck of the bottle in either of the two possible directions, so that the outer surface can be formed by the first surface  5  or by the second surface  6 . 
         [0018]    A permeable element is inserted into the passage  4 , to provide adequate regulation of the passage of oxygen between the inside and the outside of the bottle. This permeable element can be of the membrane type, as described in detail below with reference to  FIGS. 1 and 2 , or can be of the insert type, that is to say a rod-like cylindrical body, extending predominantly along the axis of the passage  4 , as described below. 
         [0019]    In the first preferred example described here, the passage  4  comprises a first cylindrical portion of reduced diameter  7 , extending from the second surface  6  towards a median portion  8  of the passage  4 , and a second portion  9 , also cylindrical but having a larger diameter, extending from the median portion  8  towards the first surface  5 . 
         [0020]    The median portion  8  is delimited towards the second portion  9  by a circular bead  10  extending radially towards the inside of the passage  4 , and it is delimited towards the first portion  7  by a shoulder  11 . 
         [0021]    The median portion  8  has surfaces slightly inclined with respect to the axis X from the bead  10  to the shoulder  11 , and forms a seat for housing a support sleeve  12  whose shape is substantially conjugate with that of the median portion  8 . The sleeve  12 , shown in greater detail in  FIG. 2 , thus has a generally truncated conical shape with a profile tapered along the axis X from its major base  13  to its minor base  14 . 
         [0022]    In the seat  8 , the sleeve  12  is positioned with its minor base bearing on the shoulder  11  and with its major base  13  next to the bead  10 . 
         [0023]    A through hole  15 , intercepted in its central area by a membrane  16  which extends transversely with respect to the axis X and is fixed to the support sleeve  12  by particular welding or moulding methods, is formed along the longitudinal axis of the sleeve  12 , coinciding with the axis X. 
         [0024]    The membrane  16  therefore intercepts the hole  15  and consequently the entire passage  4  for communication between the first and second surfaces  5  and  6  of the stopper  1 . The characteristics of the membrane  16 , described in detail below, are such as to efficiently regulate the passage of gases and vapours, particularly oxygen, through the passage  4 . 
         [0025]    In the specific case detailed here, the diameter of the hole  15  is equal to that of the first portion  7 , so as to form an extension thereof, but clearly it is possible for it to have a different diameter. The hole  15  can also have different cross sections in the portions separated by the membrane  16 . 
         [0026]    A projection  19 , extending radially towards the walls of the seat  8  from the edge of the major base  13 , is also conveniently provided around the outer shell of the sleeve  12 . 
         [0027]    The projection  19  preferably has a sharp edge, so that it can be more easily inserted into the walls of the seat  8 . 
         [0028]    The production of the stopper  1  comprises a first step of producing the main body  2  of the suitable polymer material, with the provision of the passage  4 . This step can be carried out by injection moulding, extrusion, or any other method suitable for the purpose. 
         [0029]    The support sleeve  12  is made separately, for example by injection moulding of polypropylene, polyamide or ABS, and the membrane  16  is fixed therein. 
         [0030]    The membrane  16  can be fixed to the sleeve  12  in the most suitable way. For example, in the embodiment described here, the membrane is positioned on a shoulder  17  formed in the hole  15  and retained in position by a tubular insert  18  bearing on the shoulder  17  and subsequently heat-welded. To improve the retention of the membrane, it is possible to create pointed formations (not shown in the figures) on the shoulder  17  and/or on the tubular insert  18 , projecting towards the membrane  16 , with a pressure retaining system of the flange type. 
         [0031]    Similarly, the membrane  16  can be fixed to the sleeve  12  by overmoulding the plastics material forming the sleeve on to the membrane which has previously been positioned in the mould, or by ultrasonic welding. In particular, the overmoulding method is particularly preferred if the polymer material forming the sleeve  12  and that forming the membrane  16  are chemically compatible with each other. 
         [0032]    The sleeve  12  is then inserted mechanically into the passage  4  of the main body  2 , until the minor base  14  bears on the shoulder  11 , thus defining its correct position in the seat  8 . 
         [0033]    It should be noted that the step of inserting the sleeve  12  is facilitated by its truncated conical shape and that the provision of the bead  10  prevents its movement out of the main body  2 . 
         [0034]    When the stopper  1  is inserted and engaged in the aperture  3   a  of the bottle  3 , the main body is normally subjected to radial compression which ensures that the stopper is retained in the sealing position, and that there is sufficient resistance to the passage of gases and liquids between the stopper and bottle. Following this compression, the projection  19  is pressed forcefully against the walls of the seat  8 , thus forming a means of preventing the passage of gases or liquids between the sleeve  12  and the main body  2 , and an efficient means of fixing the sleeve  12  inside the seat  8 . 
         [0035]    The membrane  16  is impermeable to liquids, and thus does not allow the passage of any liquids through it. 
         [0036]    The membrane  16  is also made from polymer material having characteristics such that it allows a sufficient flow of oxygen for the process of maturing the wine contained in the bottle, this flow being measured at approximately 0.1-5 milligrammes (mg) per month, depending on the type of wine. In particular, for most of the wines concerned, the monthly flow of oxygen which must pass from the outside to the inside of the bottle for the wine to mature correctly is in the range from 0.2 to 2 mg. 
         [0037]    If suitable allowance is made for a minimum constant quantity of oxygen which inevitably passes between the stopper and the neck of the bottle, and if the same differential partial pressure of oxygen is assumed to exist between the two sides of the membrane, this flow depends substantially on the area of the membrane exposed to the flow, on its thickness and on its permeability to oxygen. 
         [0038]    The area of the membrane  16  exposed to the flow of oxygen is identical, in the case described here, to the area of the cross section of the hole  15 , whose diameter varies from approximately 0.1 to 10 mm, preferably from 1 mm to 7 mm. The area concerned is therefore in the range from 0.0078 to 78.5 mm 2 , preferably from 0.7 to 38.5 mm 2 . 
         [0039]    On the other hand, the thickness of the membrane  16  is in the range from 5 to 2000 microns, preferably from 10 to 1000 microns. If the membrane has a thickness of less than about 100 microns, it is preferably placed on a supporting material, for example a suitably treated paper-based material, whose characteristics must be such as not to affect the permeability of the membrane. 
         [0040]    Additionally, in the case of membranes of a certain thickness, the membrane  16  can be moulded in one piece with the sleeve  12 , thus forming a monolithic permeable element made from a single material. 
         [0041]    It should be noted that, in the preferred case described here, there is only one membrane. However, it is possible to control the flow of oxygen by providing more than one membrane. In this case, it must be possible to provide an equivalent total area and an equivalent total thickness, defined as the surface and thickness of a hypothetical membrane which by itself would offer the same resistance to the flow of oxygen as the plurality of membranes provided in the stopper. 
         [0042]    The determination of this equivalent total area and thickness will clearly depend on the way in which the membranes are positioned in the stopper, for example on whether they are positioned in series in the same passage or in parallel in different passages. 
         [0043]    The oxygen permeability of the membrane  16  at ambient temperature, fixed at 20° C., is in the range from 10 −7  to 10 −11  (Ncm 3 *cm/cm 2 *cm Hg *s). 
         [0044]    The membrane  16  can be of a compact type, in other words having substantially no porosity, in which case the flow of the gas concerned through the membrane takes place by diffusion in the polymer matrix, or of a microporous type, in which case the flow of the gas takes place primarily through the micropores (Fick diffusion). 
         [0045]    Membranes of the compact type having levels of permeability within the aforesaid limits may, for example, be based on silicone rubber such as vulcanized polydimethylsiloxane (PDMS) or poly(oxydimethylsilylene). 
         [0046]    Silicone rubbers have poor chemical compatibility with the polypropylene from which the sleeve  12  is preferably made, and therefore membranes made from this material are typically kept engaged in the sleeve  12  by the method described above with reference to  FIGS. 1 and 2 . 
         [0047]    Additionally, if the material of the membrane is a silicone rubber, the membrane and the sleeve can be formed in one piece by a single moulding operation, forming a monolithic permeable element. 
         [0048]    Other examples, provided for information and not intended to be exhaustive, of materials suitable for making membranes of the compact type include:
       polydienes and their copolymers, such as polybutadiene, polyisoprene, polyisoprene hydrochloride, polymethyl-1-pentenylene, hydrogenated polybutadiene, poly(2-methyl-1,3-pentadiene-co-4-methyl-1,3-pentadiene), vulcanized trans rubber, polychloroprene and butadiene-acrylonitrile copolymer;   cellulose derivatives, such as ethylcellulose and cellulose acetobutyrate,   styrene/olefin/diene-based copolymers such as styrene-ethylene-butene-styrene (SEBS) and styrene-ethylene-propylene-styrene (SEPS),   polyoxides, such as poly(oxy-2,6-dimethyl-1,4-phenylene),   polyolefins and their derivatives, such as low-density polyethylene or ethylene-vinylacetate copolymer (EVA),   fluoridated polymers and copolymers, such as polytetrafluoroethylene and tetrafluoroethylene-hexafluoropropylene copolymer.       
 
         [0055]    Some examples of membranes made from these materials are given in the table appended to the description. 
         [0056]    The materials listed above are also more chemically compatible with polypropylene than are silicone rubbers, and they can therefore be overmoulded for the formation of the sleeve  12 . 
         [0057]    The membrane  16  can be of the composite type, formed by a single layer or by a plurality of superimposed layers, each of which can be made from any polymer, homopolymer, or polymer or copolymer mixture, which may be of a composite type and filled with inorganic filler. One of the layers can also consist of an inorganic, ceramic or zeolite material. 
         [0058]    The materials forming the aforesaid membranes can be suitably nano-filled, for example with organomodified nanoclays, silica, TiO 2 , magnesium oxide, titanium dioxide, etc., to achieve the desired oxygen permeability. 
         [0059]    For microporous membranes (including nanoporous membranes), the membrane must, according to another aspect of the invention, have a molecular cut-off of less than 50 kDalton. 
         [0060]    The molecular cut-off is a measurement correlated with the dimension of the micropores and indicates the maximum molecular weight of molecules capable of passing through the membrane by travelling through its holes. 
         [0061]    The measurement of the dimension of the micropores is of considerable importance if the stopper  1  is used in bottles containing wine intended for a long maturing process. This is because a low molecular cut-off substantially impedes the passage of complex heavy molecules from and to the inside of the bottle, including molecules of compounds important for the conservation and/or production of the final flavour properties required in the wine contained in the bottle, and also including spores, moulds and bacteria. In particular, the microporous membrane preferably has a molecular cut-off in the range from 1 to 30 kDalton, or more preferably in the range from 1 to 10 kDalton. 
         [0062]    Microporous membranes having the characteristics specified above can be made, for example, from polytetrafluoroethylene (PTFE) and have a thickness ranging from 100 to 500 microns. Their chemical compatibility with polypropylene is also sufficient to enable them to be fixed to the sleeve  12  by an overmoulding method. 
         [0063]    According to another aspect of the invention, the membrane  16  also preferably has a water vapour permeability, measured at 23° C., in the range from 50 to 500 g/m 2 d, a value at which the loss of water over time can be sufficiently controlled. 
       EXAMPLES 
       [0064]    A set of stoppers were prepared according to the above teachings, using membranes with compact materials, with different permeability, and having different areas and thicknesses. 
         [0065]    All the examples of stoppers made were tested under constant pressure and temperature, comparable with the environmental conditions in which the process of maturing a wine in the bottle normally takes place. 
         [0066]    The test results are shown in Table 1, which lists the monthly flows of oxygen through a stopper having a membrane made from a material with a permeability indicated as Perm, a thickness indicated as S, in microns, and a specific diameter indicated as D, in mm. 
         [0067]    The results which meet the flow requirements for a correct ageing process of the wine are those in the range from 0.1 to 2 mg/month, which, allowing for an oxygen exchange of approximately 0.1 mg/month through the tested stopper and the bottle neck, conform to the optimal exchange conditions for maturing a vintage wine. 
         [0068]    All the materials used, the surface dimensions, the thicknesses and the measured oxygen flows are shown in Table 1 which is provided for the purposes of this description. The positive results, in other words those relating to a flow within the aforementioned range, are shown in bold type. 
         [0069]    The results in Table 1 demonstrate that silicone rubbers require greater thicknesses, in the region of 500 microns, in order to be suitable for the required purpose, while other polymer materials must have smaller thicknesses, of approximately 100 microns, or even as little as 10 microns. 
         [0070]    A stopper  100  made according to a second example of the present invention is shown in  FIG. 3 , in which details similar to details of the preceding example are identified by the same reference numerals. 
         [0071]    In the stopper  100 , the permeable element, in this case in the form of a membrane  101 , is made from the same material as the main body  2 , and is produced simultaneously with it, by a moulding method. 
         [0072]    Clearly, this solution enables the production costs to be considerably reduced, since only one material and one operation are required, with no need for subsequent working or assembly. 
         [0073]    This material must of course have not only the appropriate permeability but also all the necessary mechanical, chemical and physical, and workability characteristics for its use in the production of the main body  2 . 
         [0074]    A preferred example of this material consists of SEBS copolymer and SEPS copolymer. By using this material, it is possible to mould the main body  2 , in one piece in a single operation, the passage  4 , sealed by a membrane  16  of suitable thickness, being formed inside the main body. In particular, where the size of the passage  4  is approximately 7 mm, the membrane  16  has a thickness of approximately 1000 microns, which is large enough to allow the moulding method to be used. 
         [0075]    In a third example of embodiment of the present invention, shown in  FIG. 4 , which represents a stopper  200 , the permeable element is of the insert type, in other words having a rod-like body  201  whose cross section is conjugate with that of the passage  4 . 
         [0076]    In this case, the predominant dimension of the permeable element is the axial dimension, which can be in the range from 2 mm to 60 mm, while the cross sections of the passage  4  are similar to those of the preceding example. 
         [0077]    In this case, since the thickness of the permeable element is greater by approximately two orders of magnitude than the thickness of the membranes of the preceding example, the permeability required in the material forming the permeable element is, correspondingly, greater by approximately two orders of magnitude, being preferably in the range from 10 −5  to 10 −9  (Ncm 3 *cm/cm 2 *cm Hg *s). Preferably, the insert is of the compact type. 
         [0078]    Thus the present invention resolves the problem of the prior art identified above, while also offering numerous other benefits. 
         [0000]    
       
         
               
               
               
             
               
               
               
               
               
               
               
             
               
               
             
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
             
             
               
                   
                 Perm 
                 Oxygen flow (mg/month) 
               
             
          
           
               
                   
                 Ncm 3  * cm/ 
                 S = 10μ 
                 S = 10μ 
                 S = 10μ 
                 S = 100μ 
                 S = 100μ 
               
               
                 Material 
                 (cm 2  * cm Hg  * s) 
                 D = 1 mm 
                 D = 1.5 mm 
                 D = 2 mm 
                 D = 1 mm 
                 D = 1.5 mm 
               
               
                   
               
               
                 PDMS 
                 8.00E−08 
                 37.18 
                 83.66 
                 148.72 
                 3.72 
                 8.37 
               
               
                 Poly(oxydimethylsilylene) with 
                 4.88E−08 
                 22.68 
                 51.04 
                 90.74 
                 2.27 
                 5.1 
               
               
                 10% Scantocel CS filler 
               
               
                 SEPS (Megol K) 
                 1.88E−08 
                 8.74 
                 19.66 
                 34.95 
                 
                   0.87 
                 
                 
                   1.97 
                 
               
               
                 Polyisoprene hydrochloride 
                 5.39E−09 
                 2.50 
                 5.63 
                 10.01 
                 
                   0.25 
                 
                 
                   0.56 
                 
               
               
                 Polymethyl-1-pentenylene 
                 3.22E−09 
                 
                   1.50 
                 
                 3.37 
                 5.98 
                 
                   0.15 
                 
                 
                   0.34 
                 
               
               
                 Polyisoprene amorphous 
                 2.34E−09 
                 
                   1.09 
                 
                 2.45 
                 4.35 
                 
                   0.11 
                 
                 
                   0.24 
                 
               
               
                 Polybutadiene 
                 1.90E−09 
                 
                   0.88 
                 
                 
                   1.99 
                 
                 3.54 
                 0.09 
                 
                   0.20 
                 
               
               
                 SEBS (Kraton G1650) 
                 1.39E−09 
                 
                   0.64 
                 
                 
                   1.44 
                 
                 2.57 
                 0.06 
                 
                   0.14 
                 
               
               
                 SEBS (Kraton G2705) 
                 2.51E−09 
                 
                   1.16 
                 
                 2.62 
                 4.66 
                 
                   0.12 
                 
                 
                   0.26 
                 
               
               
                 Poly(oxy-2,6-dimethyl-1,4- 
                 1.58E−09 
                 
                   0.74 
                 
                 
                   1.66 
                 
                 2.94 
                 0.07 
                 
                   0.17 
                 
               
               
                 phenylene 
               
               
                 Ethyl cellulose 
                 1.46E−09 
                 
                   0.68 
                 
                 
                   1.53 
                 
                 2.73 
                 0.07 
                 
                   0.15 
                 
               
               
                 Hydrogenated polybutadiene 
                 1.13E−09 
                 
                   0.52 
                 
                 
                   1.18 
                 
                 2.10 
                 0.05 
                 
                   0.12 
                 
               
               
                 Poly (2-methyl-1,3- 
                 1.00E−09 
                 
                   0.46 
                 
                 
                   1.05 
                 
                 
                   1.86 
                 
                 0.05 
                 
                   0.10 
                 
               
               
                 pentadiene-co-4-methyl-1,3- 
               
               
                 pentadiene) 85/15 
               
               
                 Polybutadiene-co-acrylonitrile 
                 8.18E−10 
                 
                   0.38 
                 
                 
                   0.86 
                 
                 
                   1.52 
                 
                 0.04 
                 0.09 
               
               
                 80/20 
               
               
                 Purified vulcanized trans 
                 6.17E−10 
                 
                   0.29 
                 
                 
                   0.65 
                 
                 
                   1.15 
                 
                 0.03 
                 0.06 
               
               
                 rubber, gutta percha 
               
               
                 Polytetrafluoroethylene-co- 
                 4.89E−10 
                 
                   0.23 
                 
                 
                   0.51 
                 
                 
                   0.91 
                 
                 0.02 
                 0.05 
               
               
                 hexafluoropropene 
               
               
                 Cellulose acetobutyrate 
                 4.73E−10 
                 
                   0.22 
                 
                 
                   0.50 
                 
                 
                   0.88 
                 
                 0.02 
                 0.05 
               
               
                 Polytetrafluoroethylene (PTFE) 
                 4.26E−10 
                 
                   0.20 
                 
                 
                   0.45 
                 
                 
                   0.79 
                 
                 0.02 
                 0.04 
               
               
                 Fluoridated polymer 
                 4.22E−10 
                 
                   0.20 
                 
                 
                   0.44 
                 
                 
                   0.78 
                 
                 0.02 
                 0.04 
               
               
                 Polychloroprene 
                 3.94E−10 
                 
                   0.18 
                 
                 
                   0.41 
                 
                 
                   0.73 
                 
                 0.02 
                 0.04 
               
               
                 Polybutadiene-co-acrylonitrile 
                 3.86E−10 
                 
                   0.18 
                 
                 
                   0.40 
                 
                 
                   0.72 
                 
                 0.02 
                 0.04 
               
               
                 73/27 
               
               
                 LDPE (low-density 
                 2.93E−10 
                 
                   0.14 
                 
                 
                   0.31 
                 
                 
                   0.54 
                 
                 0.01 
                 0.03 
               
               
                 polyethylene 
               
               
                   
               
             
          
           
               
                   
                 Oxygen flow (mg/month) 
               
             
          
           
               
                   
                 S = 100μ 
                 S = 500μ 
                 S = 500μ 
                 S = 500μ 
                 S = 250μ 
                 S = 1000μ 
               
               
                 Material 
                 D = 2 mm 
                 D = 1 mm 
                 D = 1.5 mm 
                 D = 2 mm 
                 D = 5 mm 
                 D = 7 mm 
               
               
                   
               
               
                 PDMS 
                 14.87 
                 
                   0.74 
                 
                 
                   1.67 
                 
                 2.97 
                 37.18 
                 18.21 
               
               
                 Poly(oxydimethylsilylene) with 
                 9.07 
                 
                   0.45 
                 
                 
                   1.02 
                 
                 
                   1.81 
                 
                 22.68 
                 11.12 
               
               
                 10% Scantocel CS filler 
               
               
                 SEPS (Megol K) 
                 3.49 
                 
                   0.17 
                 
                 
                   0.39 
                 
                 
                   0.70 
                 
                 8.74 
                 4.28 
               
               
                 Polyisoprene hydrochloride 
                 
                   1.00 
                 
                 0.05 
                 
                   0.11 
                 
                 
                   0.20 
                 
                 
                   2.50 
                 
                 
                   1.23 
                 
               
               
                 Polymethyl-1-pentenylene 
                 
                   0.60 
                 
                 0.03 
                 0.07 
                 
                   0.12 
                 
                 
                   1.50 
                 
                 
                   0.73 
                 
               
               
                 Polyisoprene amorphous 
                 
                   0.44 
                 
                 0.02 
                 0.05 
                 0.09 
                 
                   1.09 
                 
                 
                   0.53 
                 
               
               
                 Polybutadiene 
                 
                   0.35 
                 
                 0.02 
                 0.04 
                 0.07 
                 
                   0.88 
                 
                 
                   0.43 
                 
               
               
                 SEBS (Kraton G1650) 
                 
                   0.26 
                 
                 0.01 
                 0.03 
                 0.05 
                 
                   0.64 
                 
                 
                   0.32 
                 
               
               
                 SEBS (Kraton G2705) 
                 
                   0.47 
                 
                 0.02 
                 0.05 
                 0.09 
                 
                   1.16 
                 
                 
                   0.57 
                 
               
               
                 Poly(oxy-2,6-dimethyl-1,4- 
                 
                   0.29 
                 
                 0.01 
                 0.03 
                 0.06 
                 
                   0.74 
                 
                 
                   0.36 
                 
               
               
                 phenylene 
               
               
                 Ethyl cellulose 
                 
                   0.27 
                 
                 0.01 
                 0.03 
                 0.05 
                 
                   0.68 
                 
                 
                   0.33 
                 
               
               
                 Hydrogenated polybutadiene 
                 
                   0.21 
                 
                 0.01 
                 0.02 
                 0.04 
                 
                   0.52 
                 
                 
                   0.26 
                 
               
               
                 Poly (2-methyl-1,3- 
                 
                   0.19 
                 
                 0.01 
                 0.02 
                 0.03 
                 
                   0.46 
                 
                 
                   0.23 
                 
               
               
                 pentadiene-co-4-methyl-1,3- 
               
               
                 pentadiene) 85/15 
               
               
                 Polybutadiene-co-acrylonitrile 
                 
                   0.15 
                 
                 0.01 
                 0.02 
                 0.03 
                 
                   0.38 
                 
                 
                   0.19 
                 
               
               
                 80/20 
               
               
                 Purified vulcanized trans 
                 
                   0.11 
                 
                 0.01 
                 0.01 
                 0.02 
                 
                   0.29 
                 
                 
                   0.14 
                 
               
               
                 rubber, gutta percha 
               
               
                 Polytetrafluoroethylene-co- 
                 0.09 
                 0.00 
                 0.01 
                 0.02 
                 
                   0.23 
                 
                 
                   0.11 
                 
               
               
                 hexafluoropropene 
               
               
                 Cellulose acetobutyrate 
                 0.09 
                 0.00 
                 0.01 
                 0.02 
                 
                   0.22 
                 
                 
                   0.11 
                 
               
               
                 Polytetrafluoroethylene (PTFE) 
                 0.08 
                 0.00 
                 0.01 
                 0.02 
                 
                   0.20 
                 
                 
                   0.10 
                 
               
               
                 Fluoridated polymer 
                 0.08 
                 0.00 
                 0.01 
                 0.01 
                 
                   0.20 
                 
                 
                   0.10 
                 
               
               
                 Polychloroprene 
                 0.07 
                 0.00 
                 0.01 
                 0.01 
                 
                   0.18 
                 
                 0.09 
               
               
                 Polybutadiene-co-acrylonitrile 
                 0.07 
                 0.00 
                 0.01 
                 0.01 
                 
                   0.18 
                 
                 0.09 
               
               
                 73/27 
               
               
                 LDPE (low-density 
                 0.05 
                 0.00 
                 0.01 
                 0.01 
                 
                   0.14 
                 
                 0.07 
               
               
                 polyethylene