Patent Publication Number: US-2011076474-A1

Title: Nanocomposite composition and system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Patent Application No. 61/245,776, filed Sep. 25, 2009, which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The present disclosure generally relates to a nanocomposite composition. 
     BACKGROUND 
     Gas transport through a polymer may be modeled according to a solution-diffusion mechanism, and may be expressed as a permeability of the polymer, i.e., a rate at which gas passes through the polymer. For example, during gas transport through the polymer, a gas molecule may dissolve into the polymer from a region of relatively high pressure, diffuse through a thickness of the polymer, and desorb from a surface of the polymer to a region of comparatively low pressure. Permeability may therefore be affected by the diffusivity of the gas molecule within the polymer. 
     Such diffusivity may be expressed as a diffusivity coefficient, i.e., a measure of a mobility of the gas molecule within the polymer. As the diffusivity coefficient decreases, permeation of the gas molecule through the polymer also decreases, and gas transport through the polymer is slowed. 
     SUMMARY 
     A nanocomposite composition includes a polymer and a barrier component sufficiently dispersed within the polymer so as to define a tortuous path within the polymer. The barrier component includes a nano-constituent including a plurality of layers and a macro-constituent including a plurality of particles. Each of the plurality of layers has a first average thickness, and each of the plurality of particles has a second average thickness that is greater than the first average thickness. 
     A nanocomposite system includes a substrate and a coating disposed on the substrate. The coating is formed from the nanocomposite composition. 
     The above features and advantages and other features and advantages of the present disclosure are readily apparent from the following detailed description of the best modes for carrying out the disclosure when taken in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic illustration of a magnified portion of a nanocomposite composition including a barrier component dispersed within a polymer; 
         FIG. 2  is a schematic illustration of a magnified portion of the nanocomposite composition of  FIG. 1 , wherein the barrier component defines a tortuous path configured to inhibit gas permeation through the nanocomposite composition; 
         FIG. 3  is a schematic cross-sectional illustration of a nanocomposite system including a coating formed from the nanocomposite composition of  FIGS. 1 and 2  disposed on a substrate; 
         FIG. 4  is a graphical representation of four x-ray diffraction spectra corresponding to a nanocomposite composition of each of Example 1 and Comparative Examples 3-5; and 
         FIG. 5  is a graphical representation of gas permeability for a rubber of Control  6  and a nanocomposite composition of each of Examples 1 and 2 and Comparative Examples 4 and 5. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to the Figures, wherein like reference numerals refer to like elements, a schematic illustration of a magnified portion of a nanocomposite composition  10  is shown generally in  FIG. 1 . The nanocomposite composition  10  may be useful for applications requiring materials having decreased gas permeability, and excellent elongation at break, tensile strength, and modulus of elasticity, as set forth in more detail below. For example, the nanocomposite composition  10  may be useful for automotive applications including, but not limited to, accumulator bladders, diaphragm bladders, pressure pulsation dampener bladders, hydraulic hoses, fuel hoses, and fuel tanks. However, the nancocomposite composition  10  may also be useful for non-automotive applications including, but not limited to, packaging, foodstuff liners, containers, electronics, and other agricultural, construction, and industrial applications. 
     As used herein, the terminology “nanocomposite composition” refers to a material in which at least one constituent has one or more dimensions, such as length, width, or first average thickness  12  ( FIG. 2 ), measurable on a nanometer scale, i.e., in a nanometer size range. One nanometer is equal to 1×10 −9  meters. 
     Referring again to  FIG. 1 , the nanocomposite composition  10  includes a polymer  14 . In general, the polymer  14  may provide structure to the nanocomposite composition  10  and may be a carrier for other components of the nanocomposite composition  10 , as set forth in more detail below. Therefore, the polymer  14  may be selected according to required properties of a desired application. For example, the polymer  14  may be selected to have excellent tensile strength and/or elongation at break. The polymer  14  may be an elastomer, such as, but not limited to, rubber. For example, the polymer  14  may be selected from the group including epichlorohydrin, acrylonitrile-butadiene rubber, hydrogenated acrylonitrile-butadiene rubber, natural rubber, fluorocarbon rubber, ethylene propylene diene monomer (EPDM/EPR), butyl rubber, chlorobutyl rubber, chlorinated polyethylene, and combinations thereof. 
     As described with continued reference to  FIG. 1 , the nanocomposite composition  10  also includes a barrier component  16  sufficiently dispersed within the polymer  14  so as to define a tortuous path  36  ( FIG. 2 ) within the polymer  14 , as set forth in more detail below. As used herein, the terminology “barrier component” refers to a material or material structure, such as a layer  18  ( FIG. 2 ) or a surface  20  ( FIG. 2 ), that obstructs and/or impedes the penetration, permeation, diffusion, dissolution, movement, transport, and/or desorption of gas molecules (represented generally by  22  in  FIG. 2 ) through or beyond the material or material structure. The barrier component  16  may be thoroughly mixed within the polymer  14  so as to be uniformly dispersed throughout the polymer  14 . For example, any two separate regions of the polymer  14  may include a substantially uniform quantity of the barrier component  16 . Alternatively, the barrier component  16  may be randomly dispersed within the polymer  14 . For example, any two separate regions may include different quantities of the barrier component  16 . 
     Referring again to  FIG. 1 , the barrier component  16  includes a nano-constituent  24  including a plurality of layers  18 . As used herein, the terminology “nano-constituent” refers to a constituent of the barrier component  16  having one or more dimensions, such as length, width, or first average thickness  12  ( FIG. 2 ), measurable on the nanometer scale, i.e., in the nanometer size range. 
     As shown in  FIG. 2 , each of the plurality of layers  18  has a first average thickness  12 . In particular, the first average thickness  12  may be from about 0.5 nm to about 2 nm, e.g., about 1 nm. Layers  18  having a first average thickness  12  of less than about 0.5 nm may decrease the effectiveness of the barrier component  16  so that gas permeation through the polymer  14  is not properly impeded. Similarly, layers  18  having a first average thickness  12  of greater than about 2 nm may decrease effective dispersion of the nano-constituent  24  within the nanocomposite composition  10 . Each of the plurality of layers  18  may have a non-spherical shape, e.g., a platelet-like shape, and may have a length  26  ( FIG. 2 ) that is longer than the first average thickness  12  of the layer  18 . That is, each of the plurality of layers  18  may have an aspect ratio of from about 100:1 to about 1,000:1, e.g., about 200:1. As used herein, the terminology “aspect ratio” refers to a ratio of a longer dimension to a shorter dimension of the layer  18 , e.g., a ratio of the length  26  to the first average thickness  12  of the layer  18 . 
     In one variation, the nano-constituent  24  ( FIG. 1 ) may include a silicate having a plurality of non-ordered layers  18 , as set forth in more detail below. The silicate may be selected from the group including montmorillonite, bentonite, hectorite, saphonite, vermiculite, and combinations thereof. In one example described with reference to  FIG. 1 , the nano-constituent  24  may include individual layers  18  of the silicate that are each separated and dispersed throughout the polymer  14 . That is, the silicate may be initially procured as layered clay or nanoclay in preparation for forming the nanocomposite composition  10 , and may be characterized as 2:1 phyllosilicate. However, for the prepared nanocomposite composition  10 , the individual layers  18  of the silicate may be separated and dispersed within the polymer  14 , as set forth in more detail below. 
     In another variation, the nano-constituent  24  may include a carbon-based platelet-type nanoparticle. For example, the nano-constituent  24  may include grapheme. The nano-constituent  24  may have a first average thickness  12  ( FIG. 2 ) of about 1 nm and a length  26  ( FIG. 2 ) of less than about 1 micron. 
     The nano-constituent  24  may be present in an amount of from about 0.1 parts by weight to about 100 parts by weight based on 100 parts of the polymer  14 . In one example, the nano-constituent  24  may be present in an amount of from about 20 parts by weight to about 40 parts by weight based on 100 parts by weight of the polymer  14 . At amounts less than about 0.1 parts by weight, the barrier component  16  may not effectively impede gas permeation in the polymer  14 , and at amounts greater than about 100 parts by weight, the barrier component  16  may not sufficiently disperse within the polymer  14 . A suitable nano-constituent  24  is commercially available from Nanocor Inc. of Arlington Heights, Ill., under the trade name Nanomer®. 
     In one variation, the nano-constituent  24  may be chemically modified. Chemical modification of the nano-constituent  24  may improve the dispersion and/or the adhesion of the nano-constituent  24  within the polymer  14 . That is, chemical modification of the nano-constituent  24  may improve compatibility with the polymer  14  ( FIG. 2 ). In particular, chemical modification of the layers  18  of the nano-constituent  24  may attract the polymer  14  to spaces between adjacent layers  18  ( FIG. 2 ) of the nano-constituent  24  to thereby fill the interlayer spacing between individual layers  18  of the nano-constituent  24 . 
     In one example, the nano-constituent  24  may be chemically modified via an ion-exchange reaction to replace a hydrated cation on a surface of the layers  18  of the nano-constituent  24 . For example, the layers  18  of the nano-constituent  24  may be modified by a surfactant, a monomer group, and/or combinations thereof. A suitable surfactant includes alkylamonium. Suitable monomer groups include ammonium salt, octadecylamine, hydrogenated tallow-bis(2-hydroxyethyl) methyl ammonium salt, methyl-tallow-bis(2-hydroxyethyl) quaternary ammonium salt, octadecyltrimethyl ammonium salt, dimethyl hydrogenated tallow 2-ethylhexyl quaternary ammonium salt, and combinations thereof. 
     Referring again to  FIG. 1 , the barrier component  16  also includes a macro-constituent  28  including a plurality of particles  30 . As used herein, the terminology “macro-constituent” refers to a constituent of the barrier component  16  having one or more dimensions, such as length  32  ( FIG. 2 ), width, or second average thickness  34  ( FIG. 2 ), measurable on a scale greater than the nanometer scale, e.g., a micron scale. That is, one or more dimensions of the barrier component  16  may be in the micron size range. One micron is equal to 1×10 −6  meters. Therefore, the macro-constituent  28  is thicker than the nano-constituent  24 . 
     As shown in  FIG. 2 , each of the plurality of particles  30  has a second average thickness  34 . In particular, the second average thickness  34  may be from about 0.1 micron to about 100 microns, e.g., from about 1.7 microns to about 50 microns. Particles  30  having a second average thickness  34  of less than about 0.1 micron may decrease the effectiveness of the barrier component  16  so that gas permeation through the polymer  14  is not properly impeded. Likewise, particles  30  having a second average thickness  34  of greater than about 100 microns may decrease effective dispersion of the macro-constituent  28  within the nanocomposite composition  10 . Each of the plurality of particles  30  may have a non-spherical shape, e.g., platy, and may have a length  32  ( FIG. 2 ) that is longer than the second average thickness  34  of the particle  30 . That is, each of the plurality of particles  30  may have an aspect ratio of from about 10:1 to about 30:1, e.g., about 20:1. 
     Referring to  FIGS. 1 and 2 , the macro-constituent  28  may be selected from the group including talc, mica, i.e., phyllosilicate of aluminum or potassium, graphite, and combinations thereof. In one variation, the macro-constituent  28  may include talc, i.e., hydrated magnesium silicate, which may be represented as Mg 2 Si 4 O 10 (OH) 2 . The macro-constituent  28  may have a second average thickness  34  ( FIG. 2 ) of about 1 micron and a length  32  ( FIG. 2 ) of about 20 microns. The macro-constituent  28  may be present in an amount of from about 0.1 parts by weight to about 60 parts by weight based on 100 parts of the polymer  14 . In one example, the macro-constituent  28  may be present in an amount of from about 10 parts by weight to about 20 parts by weight based on 100 parts by weight of the polymer  14 . At amounts of less than about 0.1 parts by weight, the barrier component  16  may not effectively impede gas permeation in the polymer  14 , and at amounts of greater than about 60 parts by weight, the barrier component  16  may not sufficiently disperse within the polymer  14 . A suitable macro-constituent  28  is commercially available from Luzenac Inc. of Greenwood Village, Colo., under the trade name Mistron® Vapor R talc. 
     In one variation, the macro-constituent  28  may be chemically modified. Chemical modification of the macro-constituent  28  may improve compatibility with the nano-constituent  24  and/or the polymer  14 . The macro-constituent  28  may be chemically modified with a silane such as, but not limited to, an organosilane. Suitable silanes include methyltrimethoxysilane, aminopropyltriethoxysilane, diaminosilane, triaminosilane, and combinations thereof. However, the macro-constituent  28  may be substantially free from chemical modification by an alkyl ammonium salt so as not to interfere with compatibility of the nano-constituent  24  and the polymer  14 . 
     Without intending to be limited by theory, the macro-constituent  28  may exfoliate the nano-constituent  24  of the barrier component  16 . As used herein, the terminology “exfoliate” or “exfoliated” refers to individual layers  18  of the nano-constituent  24  dispersed throughout a carrier material, e.g., the polymer  14 . Generally, “exfoliated” denotes a highest degree of separation of layers  18  of the nano-constituent  24  and is contrasted with intercalated layers  18  as defined below. Likewise, the terminology “exfoliation” refers to a process for forming an exfoliated nano-constituent  24  from an intercalated or otherwise less-dispersed state of separation of the layers  18  of the nano-constituent  24 . In contrast, the terminology “intercalate” or “intercalated” refers to a layered constituent having merely increased interlayer spacing between adjacent layers  18 , i.e., interlayer spacing that is less than the interlayer spacing of the exfoliated nano-constituent  24 . Stated differently, exfoliated nano-constituent  24  represents the highest level of dispersion of the individual layers  18  of nano-constituent  24  within the polymer  14 . 
     Referring again to  FIGS. 1 and 2 , the nano-constituent  24  may be exfoliated and dispersed within the polymer  14 . More specifically, the polymer  14  may be interdisposed between the plurality of non-ordered layers  18 , as best shown at  10  in  FIG. 1 . That is, referring to  FIG. 2 , the layers  18  of the nano-constituent may be separated by the polymer  14  and generally have a large interlayer spacing as compared to a non-exfoliated, e.g., intercalated, constituent. For example, the interlayer spacing between each individual layer  18  of the nano-constituent  24  may be from about 4 nm to about 6 nm. 
     Further, the nano-constituent  24  may be uniformly dispersed within the polymer  14 . That is, although an orientation of the individual layers  18  of the nano-constituent  24  may differ in two separate regions of the nanocomposite composition  10  as shown in  FIG. 2 , the two separate regions may include an equal amount of the nano-constituent  24 . 
     Likewise, the macro-constituent  28  may be uniformly dispersed within the polymer  14 . That is, two separate regions of the nanocomposite composition  10  may include an equal amount of the macro-constituent  28 . Alternatively, the macro-constituent  28  may be randomly dispersed within the polymer  14 . That is, two separate regions of the nanocomposite composition  10  may include differing amounts or concentrations of the macro-constituent  28 . 
     As best shown in  FIGS. 1 and 2 , the nano-constituent  24  ( FIG. 1 ) and the macro-constituent  28  ( FIG. 1 ) may together define the tortuous path (represented generally by arrows  36  in  FIG. 2 ) or passage within the polymer  14  configured to inhibit gas permeation through the nanocomposite composition  10 . That is, the macro-constituent  28  may exfoliate the nano-constituent  24  and provide for increased interlayer spacing between adjacent individual layers  18  of the nano-constituent  24 . Further, the macro-constituent  28  may be disposed between such individual layers  18  of the nano-constituent  24  so as to interfill a portion of the interlayer spacing. Therefore, the nano-constituent  24  and the macro-constituent  28  may together inhibit gas permeation through the nanocomposite composition  10 . 
     More specifically, as described with reference to  FIG. 2 , as a gas molecule  22  enters the polymer  14  from a comparatively higher pressure feed side  38  of the polymer  14  and attempts diffusion through the nanocomposite composition  10 , each of the plurality of layers  18  of the nano-constituent  24  ( FIG. 1 ) and the plurality of particles  30  of the macro-constituent  28  ( FIG. 1 ) impede the progress of the gas molecule  22  towards a comparatively lower pressure permeate side  40  of the polymer  14 . That is, the gas molecule  22  may be obstructed by the nano-constituent  24  and the macro-constituent  28  within the polymer  14 . 
     In addition, the macro-constituent  28  ( FIG. 1 ) may lubricate individual polymer chains of the polymer  14 , reduce compound viscosity of the polymer  14 , and thereby improve processing characteristics of the polymer  14 . Further, the macro-constituent  28  may shear the nano-constituent  24  ( FIG. 1 ) within the polymer  14 . In addition, the combination of the nano-constituent  24  and the macro-constituent  28  within the polymer  14  may create a synergistic effect that encourages each of the nano-constituent  24  and the macro-constituent  28  to uniformly disperse within the polymer  14 . Without intending to be limited by theory, such uniform dispersal within the polymer  14  may also effectively decrease gas permeation through the polymer  14 . 
     The nanocomposite composition  10  ( FIG. 1 ) may further include one or more additives and/or curing agents. Suitable additives include, but are not limited to, fillers, dyes, plasticizers, antioxidants, activators, and combinations thereof. Suitable curing agents include vulcanizing agents, crosslinking agents, organic peroxides, and combinations thereof. 
     Referring now to  FIG. 3 , a nanocomposite system  42  includes a substrate  44  and a coating  46  disposed on the substrate  44 . The coating  46  is formed from the nanocomposite composition  10  ( FIG. 1 ), as set forth above. That is, the nanocomposite composition  10  may be disposable on the substrate  44  in the form of the coating  46 . 
     The coating  46  may be applied to the substrate  44  via any suitable process and/or device. For example, the coating  46  may be sprayed or roll-coated onto the substrate  44 . In addition, the coating  46  may have a thickness  48  of from about 5 microns to about 1,000 microns. Further, the substrate  44  may be any suitable material configured for supporting the coating  46 . The substrate  44  may be selected from the group including elastomers, e.g., rubber, fabric, e.g., woven para-aramid synthetic fiber, and combinations thereof. 
     Referring again to  FIG. 1 , a method of forming the nanocomposite composition  10  includes combining the polymer  14  and the barrier component  16  to form a blend, and mixing the blend to sufficiently exfoliate and disperse the nano-constituent  24  within the polymer  14  so as to define the tortuous path  36  ( FIG. 2 ) within the polymer  14  and thereby form the nanocomposite composition  10 . The polymer  14  and the barrier component  16  may be combined in any order. For example, the polymer  14  may be added to the barrier component  16 , or the barrier component  16  may be added to the polymer  14 . More specifically, the nano-constituent  24 , macro-constituent  28 , and polymer  14  may be combined simultaneously, or may each be added to the other in any order to form the blend. Further, the polymer  14  and the barrier component  16  may be combined in solid form. That is, the resulting blend may be non-aqueous. 
     The polymer  14  and the barrier component  16  may be mixed by any suitable process and/or apparatus. By way of non-limiting examples, mixing may include processes selected from the group including melt mixing, extruding, shear mixing, pulverizing, solution casting, compounding, and combinations thereof. That is, mixing may sufficiently interdisperse the nano-constituent  24  and the macro-constituent  28  within the polymer  14  so that the macro-constituent  28  may shear and/or exfoliate the nano-constituent  24  to thereby define the tortuous path  36  ( FIG. 2 ) within the polymer  14  configured to inhibit gas permeation through the nanocomposite composition  10 . Further, the polymer  14  and the barrier component  16  may be combined and mixed on full-scale production equipment. That is, the method provides for full-scale production of the nanocomposite composition  10  and is not limited to bench- or lab-scale equipment or batch sizes. 
     The method may further include chemically modifying each of the plurality of layers  18 . For example, the individual layers  18  may be chemically modified to improve the dispersion, adhesion, and/or compatibility of the nano-constituent  24  ( FIG. 1 ) within the polymer  14 . In particular, chemically modifying the nano-constituent  24  may attract the polymer  14  to interlayer spacing between adjacent layers  18  of the nano-constituent  24  to thereby fill the interlayer spacing between individual layers  18  of the nano-constituent  24 . 
     In one example, the nano-constituent  24  ( FIG. 1 ) may be chemically modified via an ion-exchange reaction to replace a hydrated cation of the nano-constituent  24 . For example, the nano-constituent  24  may be modified by a surfactant, a monomer group, and/or combinations thereof, as set forth above. 
     The method may further include chemically modifying each of the plurality of particles  30  ( FIG. 1 ). Chemically modifying of the macro-constituent  24  ( FIG. 1 ) may improve compatibility of the macro-constituent  28  ( FIG. 1 ) with the nano-constituent  24  and/or the polymer  14 . In one example, the macro-constituent  28  may be chemically modified with a silane such as, but not limited to, an organosilane, as set forth above. However, the macro-constituent  28  may not be chemically modified by an alkyl ammonium salt so as not to diminish compatibility of the nano-constituent  24  and the polymer  14 . 
     The method may also include combining the blend and one or more additives and/or curing agents. Suitable additives include, but are not limited to, fillers, dyes, plasticizers, antioxidants, activators, and combinations thereof. Suitable curing agents include vulcanizing agents, crosslinking agents, organic peroxides, and combinations thereof. 
     The nanocomposite composition  10  and system  42  exhibit decreased gas permeability. In particular, the nano-constituent  24  and the macro-constituent  28  interact to impede gas transport through the polymer  14 . As such, the nanocomposite composition  10  and system  42  are useful for applications requiring materials having decreased gas permeability, and excellent elongation at break, tensile strength, and modulus of elasticity. 
     The following examples are meant to illustrate the disclosure and are not to be viewed in any way as limiting to the scope of the disclosure. 
     EXAMPLES 
     To prepare the nanocomposite compositions of Examples 1 and 2 and Comparative Examples 3-5, components A-G are combined in the amounts listed in Table 1. Specifically, the nanocomposite compositions of each of Examples 1 and 2 and Comparative Examples 4 and 5 are prepared by compounding component B and/or component C in component A with Additives D and E in a Banbury Mixer BR 1600 at a rotor speed of 55 revolutions per minute for 5 minutes to prepare respective homogeneous blends. Additive F and Curing AgenteG are combined with each of the homogeneous blends and mixed for an additional 2 minutes to form the respective nanocomposite compositions of Examples 1 and 2 and Comparative Examples 4 and 5. Each of the resulting nanocomposite compositions is mixed on a roll mill to form a sheet, and cured to form plaques for evaluation according to the test methods set forth below. The amounts of components B-G listed in Table 1 refer to parts by weight based on 100 parts by weight of component A. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Nanocomposite Compositions 
               
            
           
           
               
               
               
               
               
               
            
               
                   
                   
                   
                 Comp. 
                 Comp. 
                 Comp. 
               
               
                   
                 Ex. 1 
                 Ex. 2 
                 Ex. 3 
                 Ex. 4 
                 Ex. 5 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
            
               
                 Component A 
                 100 
                 100 
                 — 
                 100 
                 100 
               
               
                 Component B 
                 10 
                 20 
                 100 
                 20 
                 40 
               
               
                 Component C 
                 20 
                 20 
                 — 
                 — 
                 — 
               
               
                 Additive D 
                 50 
                 50 
                 50 
                 50 
                 50 
               
               
                 Additive E 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
                 2.5 
               
               
                 Additive F 
                 5 
                 5 
                 5 
                 5 
                 5 
               
               
                 Curing Agent G 
                 5 
                 5 
                 5 
                 5 
                 5 
               
               
                   
               
            
           
         
       
     
     Component A is hydrogenated acrylonitrile-butadiene rubber commercially available from Zeon Chemicals L.P. of Louisville, Ky., under the trade name Zetpol®. 
     Component B is 2:1 layered phyllosilicate and includes a plurality of layers each having a first average thickness of 1 nm. Component B is commercially available from Nanocor Inc. of Arlington Heights, Ill., under the trade name Nanomer®. 
     Component C is hydrated magnesium silicate, i.e., talc, and includes a plurality of particles each having a second average thickness of 50 microns. Component C is commercially available from Luzenac Inc. of Greenwood Village, Colo., under the trade name Mistron® Vapor R talc. 
     Additive D is carbon black. Component D is commercially available from Columbian Chemicals Company of Marietta, Ga. 
     Additive E is 4,4′-bis dimethylbenzyl diphenylamine. Component E is commercially available from Chemtura Corporation of Middlebury, Conn. 
     Additive F is a combination of zinc oxide, commercially available under the trade name Kadox® 911 from Horsehead Corporation of Monaca, Pa., and stearic acid, commercially available under the trade name INDUSTRENE® R from Akrochem Corporation of Akron, Ohio. 
     Curing Agent G is 1,1′-bis(t-butylperoxy)-diisopropylbenzene. Curing Agent G is commercially available from GEO® Specialty Chemicals of Gibbstown, N.J., under the trade name Vul-Cup® 40KE. 
     After compounding, the resulting nanocomposite compositions of Example 1, Comparative Example 4, and Comparative Example 5 have a thickness of 500 microns. 
     In contrast, the nanocomposite composition of Example 2 is roll-coated onto a natural rubber substrate to form a nanocomposite system including a coating disposed on the substrate. The resulting coating formed from the nanocomposite composition of Example 2 has a thickness of 750 microns, and the natural rubber substrate has a thickness of 2 cm. 
     Each of the nanocomposite compositions of Examples 1 and 2 and Comparative Examples 3-5 is evaluated according to the test procedures set forth below. 
     X-Ray Diffraction 
     Each of the nanocomposite compositions of Examples 1 and 2 and Comparative Examples 3-5 is evaluated to determine an interlayer spacing between the plurality of layers of component B on a Scintag XDS2000 diffractometer in a Bragg-Brentano geometry. Each nanocomposite composition is scanned in a continuous symmetric scan with a step size of 0.02° at a scan rate of 0.5°/min. The scan range in 20 is from 1° to 10°. The tube and director fixed slits are 0.3°, 0.5° and 1°, 0.2°, respectively. The x-ray radiation is a CuK α1 , λ=1.5418 Å. Patterns and data are processed with MDI JADE 9+ software. 
       FIG. 4  is a graphical representation of four x-ray diffraction spectra of the nanocomposite compositions of each of Example 1 and Comparative Examples 3-5, wherein θ is a scattering angle of the x-ray beam. Each peak of the x-ray diffraction spectra corresponds to atomic distances and interlayer spacing of the nanocomposite compositions. 
     Referring to  FIG. 4 , the x-ray spectra of the nanocomposite composition of Comparative Example 3 indicates one peak at 1.84 nm. That is, the interlayer spacing between the plurality of layers of component B is 1.84 nm. In contrast, the x-ray spectra of the nanocomposite compositions of Comparative Examples 4 and 5, which include component B compounded in component A, indicates two peaks; a first peak is at 1.84 nm and a second peak is at 3.78 nm. Therefore, some of the interlayer spacing between the plurality of layers of the nanocomposite compositions of Comparative Examples 4 and 5 is greater than 1.84 nm. The two peaks indicate an expanded interlayer structure, and as such, the nanocomposite compositions of Comparative Examples 4 and 5 are intercalated. 
     By comparison, described with continued reference to  FIG. 4 , the x-ray spectra of the nanocomposite composition of Example 1, which includes both phyllosilicate (component B) and talc (component C), is free from a sharp peak at both 1.84 nm and 3.78 nm. Rather, the x-ray spectra of the nanocomposite composition of Example 1 indicates a broad peak at 4.48 nm and prominent scattering for 2θ of less than 2. That is, the nanocomposite composition of Example 1 includes irregular packing and spacing of the plurality of layers of the phyllosilicate (component B). Therefore, the nanocomposite composition of Example 1 is exfoliated rather than intercalated. Without intending to be limited by theory, since Example 1 includes both phyllosilicate (component B) and talc (component C), the talc may exfoliate the phyllosilicate (component B) and provide for increased interlayer spacing between adjacent individual layers of the phyllosilicate (component B). 
     Gas Permeability 
     The nanocomposite compositions of each of Examples 1 and 2 and Comparative Examples 4 and 5 are evaluated for gas permeability at 23° C. and 80° C. according to test method ASTM D 1434-82. Control  6 , a hydrogenated acrylonitrile-butadiene rubber, is also evaluated for gas permeability according to the aforementioned test method and compared to the nanocomposite compositions of each of Example 1 and 2 and Comparative Examples 4 and 5. The results of the gas permeability testing are illustrated in  FIG. 5 . 
     The nanocomposite compositions of Examples 1 and 2, which include both phyllosilicate (component B) and talc (component C), have a lower gas permeability than the rubber of Control  6 . In comparison, the nanocomposite compositions of each of Comparative Examples 4 and 5 have higher gas permeability than the nanocomposite compositions of Examples 1 and 2 for the same loading of phyllosilicate (component B). As such, the nanocomposite compositions of Examples 1 and 2 exhibit improved gas permeability as compared to the nanocomposite compositions of Comparative Examples 4 and 5. 
     Tensile Strength 
     The nanocomposite compositions of each of Examples 1 and 2 and Comparative Examples 4 and 5 are evaluated for tensile strength according to test method ASTM D 412. Control  6 , a hydrogenated acrylonitrile-butadiene rubber, is also evaluated for tensile strength according to the aforementioned test method and compared to the nanocomposite compositions of each of Examples 1 and 2 and Comparative Examples 4 and 5. The results of the tensile strength testing are listed in Table 2. 
     
       
         
           
               
             
               
                 TABLE 2 
               
               
                   
               
               
                 Tensile Strength 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Ex. 1 
                 2,880 psi 
               
               
                   
                 Ex. 2 
                 2,680 psi 
               
               
                   
                 Comp. Ex. 4 
                 2,998 psi 
               
               
                   
                 Comp. Ex. 5 
                 2,610 psi 
               
               
                   
                 Control 6 
                 2,928 psi 
               
               
                   
                   
               
            
           
         
       
     
     The nanocomposite compositions of Examples 1 and 2, which include both phyllosilicate (component B) and talc (component C), have a comparable tensile strength to the rubber of Control  6 . The addition of component B and component C does not significantly decrease the tensile strength of the nanocomposite compositions of Examples 1 and 2 as compared to the rubber of Control  6 . 
     Elongation at Break 
     The nanocomposite compositions of each of Examples 1 and 2 and Comparative Examples 4 and 5 are evaluated for elongation at break according to test method ASTM D 412. Control  6 , a hydrogenated acrylonitrile-butadiene rubber, is also evaluated for elongation at break according to the aforementioned test method and compared to the nanocomposite compositions of each of Examples 1 and 2 and Comparative Examples 4 and 5. The results of the elongation at break testing are listed in Table 3. 
     
       
         
           
               
             
               
                 TABLE 3 
               
               
                   
               
               
                 Elongation at Break 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Ex. 1 
                 430% 
               
               
                   
                 Ex. 2 
                 400% 
               
               
                   
                 Comp. Ex. 4 
                 469% 
               
               
                   
                 Comp. Ex. 5 
                 408% 
               
               
                   
                 Control 6 
                 426% 
               
               
                   
                   
               
            
           
         
       
     
     The nanocomposite compositions of Examples 1 and 2, which include both phyllosilicate (component B) and talc (component C), and Comparative Examples 4 and 5 have an acceptable elongation at break when compared to the rubber of Control  6 . As such, the inclusion of both phyllosilicate (component B) and talc (component C) in the nanocomposite composition of Example 1 does not unacceptably decrease elongation at break. 
     Modulus of Elasticity 
     The nanocomposite compositions of each of Examples 1 and 2 and Comparative Examples 4 and 5 are evaluated for modulus of elasticity at 50% strain according to test method ASTM D 412. Control  6 , a hydrogenated acrylonitrile-butadiene rubber, is also evaluated for modulus of elasticity at 50% strain according to the aforementioned test method and compared to the nanocomposite compositions of each of Example 1 and Comparative Examples 4 and 5. The results of the modulus of elasticity testing are listed in Table 4. 
     
       
         
           
               
             
               
                 TABLE 4 
               
               
                   
               
               
                 Modulus of Elasticity 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
            
               
                   
                 Ex. 1 
                 498 psi 
               
               
                   
                 Ex. 2 
                 742 psi 
               
               
                   
                 Comp. Ex. 4 
                 507 psi 
               
               
                   
                 Comp. Ex. 5 
                 713 psi 
               
               
                   
                 Control 6 
                 215 psi 
               
               
                   
                   
               
            
           
         
       
     
     The nanocomposite compositions of Examples 1 and 2, which include both phyllosilicate (component B) and talc (component C), have a higher modulus of elasticity than the rubber of Control  6 . As such, the nanocomposite compositions of Examples 1 and 2 exhibit a greater modulus of elasticity than the nanocomposite compositions of Comparative Examples 4 and 5 for the same loading of component B. 
     While the best modes for carrying out the disclosure have been described in detail, those familiar with the art to which this disclosure relates will recognize various alternative designs and embodiments for practicing the disclosure within the scope of the appended claims.