ADHESION OF A REINFORCING CORD FOR A RUBBER MATRIX

A method forms an adhesion joint between a cord and a rubber matrix. The method includes the steps of: providing a cord having an initial relatively smooth surface; texturing the smooth surface such that the resulting surface is rougher than the initial surface of the cord; depositing a uniform polymer coating on to the textured surface of the cord by plasma polymerization of an organic precursor and an air plasma; and inserting the cord into a rubber matrix such that the resulting surface provides enhanced adhesion to the rubber matrix compared to the adhesion of the initial surface to the rubber matrix or adhesion of the textured surface to rubber matrix.

DETAILED DESCRIPTION OF AN EXAMPLE OF THE PRESENT INVENTION

Reference will now be made in example detail to compositions, embodiments, and methods of the present invention known to the inventors. However, it should be understood that disclosed embodiments are merely exemplary of the present invention which may be embodied in various and alternative forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, rather merely as representative bases for teaching one skilled in the art to variously employ the present invention.

In accordance with part of the present invention, a laser may form a micro-texture at the surface of tire reinforcing cords, such as cords of steel, inorganic material, organic material, aramid, etc. The micro-texture may roughen the smooth surface thereby improving adhesion between the cords and the rubber matrix of the tire, thereby improving the durability and fatigue performance of the tire. The micro-texture may be varied by adjusting the wavelength, focus (or accuracy), continuity of power, and/or angle of incidence of the laser. The power may have a power/accuracy comparable to conventional medical lasers.

An example method for achieving a micro-textured surface on a metal wire is shown inFIG. 4. The initial rod may be steel, as described below. Carbon, C, the main strengthening element, may be present in the amount of 0.95 to 1.3%. A steel with carbon content of 0.95 to 1.05% may be processed to have a fine pearlitic structure characterized by a good combination of high ductility and strength. When the carbon content is greater than 1.05%, formation of cementite networks around blocks of pearlite colonies may occur. The increased carbon may result in a higher volume fraction of cementite leading to increased strength of the steel, but may dramatically reduce local ductility of the wire because broken cementite networks may cause crack formation.

However, the characteristics of the steel may be controlled by a defined chemical composition and processing to provide a high strength wire with ductility sufficient for wire drawing without premature cracks. A steel wire may be processed to have ductile properties similar to a 0.96% C steel with improved strength. Chromium, Cr, may be present in amounts of 0.2 to 1.8%. Cr reduces a carbon diffusion rate resulting in both refining of the pearlite and reducing the thickness of the pro-eutectoid cementite network during patenting. The Cr may partition into cementite, affecting the cementite crystal structure and thereby reducing the cementite brittleness. If the amount of Cr is less than 0.2%, the addition may induce a poor effect. Conversely, if the amount of Cr is greater than 1.8%, hardenability becomes high and martensite or bainite may be formed during patenting, resulting in deterioration of cold workability.

Manganese, Mn, may be present in amounts of 0.2 to 0.8%. Mn is a strong solid solution strengthener of ferrite. When the Mn content is less than 0.2%, the strengthening effect may not be achieved, and when the Mn content is in excess of 0.8%, there may be a deterioration of cold workability, particularly due to a higher number of Mn—S inclusions.

Silicon, Si, may be present in amounts of 0.2 to 1.2%. Si imparts a strong solid solution strengthening on ferrite. When the Si content is less than 0.2%, the effect may be lost, and when the Si content is greater than 1.2%, the silicate inclusions may form thereby increasing the probability of wire breakage during drawing.

Cobalt, Co, if present, may be not more than 2.2%. Co suppresses the formation of cementite networks in the steel when the carbon content is greater than 1.0%. If the amount of Co is greater than 2.2%, cobalt inclusions may form, negatively affecting wire drawability. Co also produces additional cost.

Niobium, Nb, if present, may be not more than 0.1% when carbon content is greater than 1.0%. The small amount of Nb may control the size of pearlite colonies by limiting growth of austenite grains at the austenitization stage of patenting and may prevent formation of large particles that may result in wire breaks during drawing. Small Nb may precipitate at austenite grain boundaries preventing excessive austenite grain growth, thereby improving wire ductility.

Boron, B, may be present in amounts of 0.006-0.0025 parts per million (ppm). The small amount of B may affect the structure of crystalline interfaces. During wire drawing, the volume fraction of ferrite/cementite interlamellar interfaces may increase up to ten percent. Boron atoms may aggregate at grain boundaries, thereby eliminating de-cohesion. Additionally, boron may tie free nitrogen, thereby reducing strain aging during drawing and improving ductility.

Exemplary Compositions for the Steel in Table 1.

After the desired steel composition is determined, the steel may be hot rolled into wires with an initial diameter of about 4.0 mm to about 5.5 mm. The wire may be directly drawn for an initial diameter reduction, patented to the tensile strength desired, brass plated, and finely drawn to reduce the wire to a final diameter of about 0.1 to 0.35 mm.

The hot rolled steel may be free of centerline carbon segregation with non-deformable inclusions having a size not more than 10 microns. The network of pro-eutectoid cementite, if present, may have a thickness of not more than 20 nm.

Each of the steps inFIG. 4is described below. After the steel is hot rolled to an initial rod diameter of about 4.0 to about 5.5 mm, the rod may be subjected to a rough/direct draw. During the rough/direct draw, by using a dry drawing lubricant at a drawing rate up to 14 m/sec, the rod diameter may be reduced to a wire with a diameter between about 1.1 mm to about 2.0 mm.

Following the rough/direct draw, the wire may be subject to intermediate patenting, which may include heat treating the wire to remove the effects of the rough/direct draw. Following the intermediate patenting, the wire may be subject to an intermediate draw/pass wherein the diameter of the wire is reduced to between about 0.15 mm to about 0.2 mm. Following the intermediate draw/pass, the wire may be subject to a fine patenting, which may include heat treating the wire to remove the effects of the intermediate draw. Following the fine patenting, the wire may be plated with brass to improve adhesion to the rubber matrix. Following the brass plating, the wire may be subject to a fine draw/pass wherein the diameter of the wire may be reduced by approximately 4.0% to about 0.15 mm. Following the fine draw/pass, in accordance with the present invention, a laser may form a micro-texture at the surface of the wire for improving adhesion between the wire and the rubber matrix of a tire, thereby improving the durability and fatigue performance of the tire (left arrow inFIG. 4). The wire may then be combined with other micro-textured wires to form a cable that may be used for reinforcing part of a tire. Alternatively the wire may be cabled following the fine draw/pass and the resulting cable may be micro-textured by a laser (right arrow inFIG. 1).

During an example patenting process, the ductility of the wire may be improved and the wire may have a microstructure capable of yielding the target strength required of the wire. The example patenting process may have three distinct steps: austenitization, cooling, and transformation. During austenitization, the wire may be quickly heated to an initial high temperature within the range of 930° to about 1100° C. The furnace temperature in the first furnace section may be about 50° C. to 100° C. higher than the targeted austenitization temperature such that the wire may be heated faster to the desirable temperature. After the wire is heated to the initial high temperature, the wire may pass into at least one lower temperature furnace section to maintain a desired wire temperature. Temperature in the remaining furnace zones may gradually taper down to the target austenitization temperature in the last zone.

The wire may be given sufficient time for the alloy to be fully austenitized as it passes through the different heating sections; however, the wire may not be subjected to an excessive heating period. The goal in this example step may be a small austenite grain size (e.g., 50 microns or less). The temperature gradient experienced by the wire may result in a formation of a fine grained austenite microstructure yielding improved ductility characteristics of the patented wire. Heating of the wire may be accomplished by electric resistance, fluidized bed, or an electric or gas fired furnace. The duration in each furnace may depend on furnace length and wire speed.

After passing through the heated zones, as described above, the wire may be rapidly cooled to a temperature below the ideal transformation temperature. Typical transformation temperatures may range from 525° C. to 620° C., depending on the amount of the alloying elements. The wire may be cooled to a temperature of about 20° C. to about 80° C. below the ideal temperature. This lower temperature may become the transformation temperature of the wire being worked.

The wire may be cooled at a rate higher than 30° C. per second, or even 50° C. per second. The wire may be cooled to the desired temperature within a period of 4 seconds or less. By quickly quenching the wire to a lower temperature, formation of a thick network of pro-eutectoid cementite may be suppressed thereby improving ductility of the wire.

After the wire is rapidly cooled to a transformation temperature, similar to the austenitization phase, the wire may pass through multiple, different temperature heat zones. The temperature in the first zone may be set to maintain the wire temperature at the transformation temperature. The second temperature zone may be 10° C. to 20° C. less than the prior zone to compensate for heat generated by the wire as transformation from the austenite phase to the pearlite phase progresses and to thereby prevent the wire from overheating. The time in the second zone may be approximately half of the total duration for the wire to transform; total time may be dependent upon the length of time for the wire to achieve full transformation and the exact wire composition.

By employing a temperature gradient at this transformation step, the release of latent heat may result in fine pearlitic microstructure with an interlamellar spacing of less than 60 nm, thereby improving strength characteristics of the wire. After the transformation is fully completed, the wire may be cooled to ambient temperature.

During an example fine drawing process, a tapered draft or a mixed tapered-even area reduction draft may be employed. The wire may be drawn through a die with an 8° approach angle. Again, similar to the direct draw, the wire may be subject to a skin pass wherein the diameter of the wire is reduced by 4% for the purpose of reducing delamination.

By using the above die design and process and applying true strains of greater than 3.8, and preferably 3.9 to 4.5 as defined by εd=2 ln(do/d) where dois the starting wire diameter and d is the final diameter filament of tensile strength greater than 3800 MPa at wire diameters 0.35 mm are achieved and wires with a tensile strengths greater than 4500 MPa at 0.20 mm are possible. For example, the true strain in the drawing of 1.65 mm wire to 0.20 mm diameter filament is 4.2.

As stated above, prior to a fine draw, the wire may be treated for corrosion resistance and to improve wire drawability. Joining of metals by adhesion is a conventional alternative to welding and mechanical fastening because adhesion joints may eliminate local stress concentrations and thermal distortion, and reduce weight by eliminating rivets, screws, and/or other fasteners. However, the durability of an adhesion joint may largely depend on the joint design, type of adhesive, and the surface structure of the adherent. Metallic medical implants may be used for internal fixation of body parts, such as bones. Some of these implants may be removed after a fractured bone is healed. Other implants, such as dental implants and joint replacements, may remain in the body indefinitely. As a result, strong and rapid fixation between a metallic implant and bone tissue has been of prime importance to surgeons. Different surface texturing techniques have thus been conventionally utilized. Some conventional fixation methods may be: (1) to use bone cement or ceramic coating for direct chemical bonding; (2) to use a screw thread for mechanical locking; and (3) to make use of the surface texture on the implant to facilitate the attachment of bone cells, and subsequently bone tissue growth on the implant.

The advantages for laser micro-drilling of medical implants, compared with other technologies, may produce highly precise machining and complex geometries. The more holes drilled on the adherent surface, the more mechanical locking sites may result. Similarly, the more holes on the medical implant surface, the easier bone cells may attach, resulting in higher adhesion strength. Thus, the adhesion strength of metal surfaces subject to different surface texturing treatment may be increased by micro-texturing, such as by laser, sand-blasting, electro-erosion, acid treatment, etc. In accordance with part of the present invention, this principle also applies to metal surfaces adhering to a rubber matrix, as stated above.

Referring toFIG. 1, in an example atmospheric pressure air plasma (APAP) system1in accordance with part of the present invention, a polymerizable material in the form of prepolymer in a feedstock vessel22may be supplied in metering tube30using a mass flow controller32and vaporized and mixed with a carrier gas in mixing chamber38. The carrier gas may be supplied from a carrier gas feedstock vessel36and introduced through a meter34into the mixing chamber38. This mixture may be introduced into an atmospheric pressure air plasma apparatus44containing the plasma of ionized gas. The ionized gas may come from a ionization gas feedstock vessel40through a meter42. The ambient air pressure around the air plasma apparatus44may range from greater than 50 kilopascals, 75 kilopascals, or 100 kilopascals, and less than 300 kilopascals, 250 kilopascals, 200 kilopascals, or 150 kilopascals. At an exit nozzle50, the high-velocity polymer reaction coating may achieve velocities greater than 10-m/s, 50-m/s, or 75-m/s, and less than 200-m/s, 150-m/s, or 125-m/s. The gases may exit the nozzle50at a temperature less than 450° C., 400° C., 350° C., 325° C., or 300° C., and greater than 70° C., 100° C., 125° C., or 150° C. The temperature of the substrate58may be less than 95° C., 85° C., 75° C., 70° C., 65° C., 60° C., 55° C., or 50° C., depending upon the conditions of operation. This temperature at the substrate58allows this process to work with substrates that are susceptible to heat damage.

The gases from the exit nozzle50may be a spray pattern with the outer penumbra56having mostly ionized gas for cleaning and/or activating. Closer to the center of the spray pattern may be an area of the higher concentration54of high-velocity impact polymer reaction coating material. The substrate58receiving the high-velocity impact polymer reaction coating64may be a rubber reinforcement material.

The substrate58may be activatable by ionization and heat and may be in pristine condition, having a covering of debris, or be corroded. The substrate58may be cleaned, and partially activated, by an atmospheric pressure air plasma. When the atmospheric pressure air plasma is also a device depositing high-velocity impact polymer coatings, the penumbra56of the atmospheric pressure air plasma exiting from the nozzle50may have a cleaning function associated with the ionization and heat. Accordingly, the time period between the cleaning and/or activation step and the deposition step may be greater than 1 ms, 5 ms, 10 ms, 25 ms, or 100 ms.

One or more separate atmospheric pressure air plasmas may be provided to clean and/or activate the surface, followed by one or more separate atmospheric pressure air plasmas depositing high velocity impact polymer coatings. The APAPs may be operated in a sequential manner, in a parallel manner, or a combination thereof. When operated as a parallel set of multi-APAPs, typical spacing may be about 2 mm.

The cleaning and/or activating operation may be capable of operating at higher travel speeds than the deposition operation or a combined cleaning and/or activating operation, as well as a deposition operation. A cleaning operation using broader width passes and a deposition operation using raster-type passes may also be included. The cleaning and/or activating operation may be accomplished using other ionization technologies, such as corona discharge or combustion sources. The time periods between the cleaning/activation step and deposition may be greater than 0.1 s, 1 s, 5 s, 10 s, 25 s, or 100 s, and less than 150 s, 300 s, 600 s, 1800 s, 3600 s, 12 hr, 1 day, 2 days, or 5 days.

Gradients of prepolymers may be developed where an additional feedstock vessel24holding other prepolymers feeds through a supply line26to the prepolymer feedstock vessel22in order to incrementally adjust the ratio or ratios of the prepolymers in the feedstock. Other prepolymers may be fed through a supply line28to a metering device32that may be adjusted incrementally or step-wise based on the ratio or ratios of prepolymers.

The APAP may deliver a plasma air treatment to the substrate58to reactivate the substrate. For example, the substrate58may be cleaned and coated in one location, and then shipped to a second location for reactivation at a later time.

Plasma polymerization yields polymers in arrangements not typically found under normal chemical conditions. The polymers may be have highly branched chains, randomly terminated chains, or functional crosslinking sites. Absent are regularly repeating units, in general. This is a result of the fragmentation of the prepolymer molecules when they are exposed to the high-energy electrons inherent in the plasma. The reactions appear to proceed by several reaction pathways including free radical formation, homolytic cleavage, cationic oligomerization, and combinations thereof.

The deposit resulting from reaction in an atmospheric pressure air plasma differs from some conventional polymers, oligomers, and monomers. In some conventional monomers, oligomers, and polymers, there is a standard series of one or more building block units, also called mers. As the polymeric chains grow the building block units are repeated and occasionally cross-linked. In a plasma polymer, the building block units may be fragmented and have new functional groups developed. When they recombine, there may be generally higher crosslink density, an increased presence of branched chains, randomly terminated chains, or a combination thereof. The crosslink density calculation becomes more difficult as the number of cross links divided by the number of backbone atoms approaches unity. Such may be the case in plasma polymers. A relative measure of the crosslink density may be the shift in glass transition temperature relative to the conventional polymer. One may expect that at low degrees of crosslinking the shift upwards of the glass transition temperature will be to the number of crosslinks. In plasma polymers, the slope of the proportion may increase relatively by about 10%, 15%, or 20% compared to conventional polymers.

Prepolymers that may be suitable for deposition by atmospheric pressure air plasma include compounds that can be vaporized. The vapors may be metered and blended with a carrier gas. This mixture of gases may be introduced into a plasma generated by an atmospheric pressure air plasma. The ionization gas of the atmospheric pressure air plasma may be chosen from gases typical of welding processes which may include, but are not limited to, noble gases, oxygen, nitrogen, hydrogen, carbon dioxide, and combinations thereof.

Prepolymers used to create a high velocity impact polymer coating may include, but are not limited to, reactive substituted compounds of group14. Candidate prepolymers do not need to be liquids, and may include compounds that are solid but easily vaporized. They may also include gases that compressed in gas cylinders, or are liquefied cryogenically and vaporized in a controlled manner by increasing their temperature.

It would be desirable to coat the external surface of tire beads or cords to promote adhesion to the surrounding bead area rubber compound matrix. As described above, plasma deposition of polymerizable material and in-situ polymerization/crosslinking via ions of the plasma may produce films which promote adhesion to a substrate, such as rubber. The effectiveness of this method partially depends on the uniform deposition of a very thin film of the adhesion promoter.

A conventional plasma nozzle may be modified in accordance with the present invention to allow the continuous and concentric feed-through of a bead, cord, or any other elongated cylindrical object. A central bore of the modified nozzle may enable the elongated cylindrical object to pass through a center of a plasma stream, resulting in a uniform exposure of the elongated cylindrical object's surface to the plasma, and the uniform deposition of adhesion promoter.

The nozzle thus provides uniform plasma deposition of adhesion coatings on tire beads and cords that may significantly reduce cost and enhance tire properties relative to conventional nozzles. Conventionally, plasma nozzles were merely passed along one side of the bead leading to a non-uniform surface coating. Multiple passes along different sides of the bead improved the coating uniformity, though not significantly enough. Further, these multiple passes increased the process time and the amount of reagent used. Use of the plasma nozzle of the present invention, with a concentric fee-through of the bead, allows for the single-pass treatment of the bead while minimizing the consumption of coating reagent.

A plasma polymerization nozzle200, as inFIG. 2, may consist of a metallic mixing chamber210where an organic precursor201is injected upstream and completely mixed with a plasma stream203prior to coming out of a round-shaped nozzle. As described above, this type of nozzle does not efficiently produce a uniform coating of a tire bead.

As shown inFIG. 3, a nozzle300in accordance with part of the present invention has a cylindrical body307with a coaxial and conical inlet310for receiving the plasma303and the tire bead305and a radial inlet320for receiving the organic precursor301. The plasma303and tire bead305pass axially from the conical inlet310through a cylindrical shield chamber312having a diameter only somewhat larger than the tire bead itself. The axial length of the cylindrical shield chamber312may protect the tire bead305from premature deposition of the polymer (i.e., before appropriate mixing can occur). The plasma303and the tire bead305then pass axially into a mixing chamber325. The organic precursor301passes radially from the radial inlet320to the mixing chamber325of the nozzle300. Mixing of the plasma303and the organic precursor301occurs in the mixing chamber325, thereby surrounding the cylindrical surface of the tire bead305and depositing a thin uniform polymer coating on the entire surface of the tire bead. The tire bead305may be fed through the nozzle300thereby providing a continuous process for coating tire bead stock of any length.

A pneumatic tire and method in accordance with the present invention may combine the two above described methods for improving cord adherence to a rubber matrix at the cord surface rubber interface. The use of steel or textile cord micro-texturing combined with the deposition of a thin plasma coating improves rubber-cord adhesion and durability.

The laser texturing part of the present invention may be conducted on twisted cables and/or filaments. The textures on the cord may intrinsically improve the mechanical aspect of the adhesion to rubber while the ultra-thin plasma coating applied to the textured cord may provide a chemical aspect to the adhesion. The depth of the texturing may not exceed the thickness of the plating (approximately 2 to 5 micrometers) because bare/untextured metal or textile cords may be exposed which may quickly lead to a detrimental rust/bubble/separation formation.

FIG. 5shows schematic representation of one example procedure1000in accordance with the present invention. Electrogalvanized UT filaments1010may be fed to a cabling module1020. From the cabling module1020, the cord/cable1100may be fed to a steam cleaning module1030for removing contaminants, such as drawing lubricants. From the steam cleaning module1030, the cord1100may be fed to a laser texturing module1040for creating a pattern with a predetermined roughness at the surface of the cord1100(e.g., micro-texturing). From the laser texturing module1040, the cord1100may be fed to plasma coating module1050for plasma polymerization of the cord1100by a predetermined mixture of precursor onto the textured cord. Form the plasma coating module1050, the cord1100may be fed to a shipping module1060for preparing the cord for shipping (e.g., spools, etc.). Form the shipping module1060the appropriately packaged cord1101may be shipped a tire plant1070for plying operations, such as in a creel room. Cords1101treated according to this process1000have shown to exhibit enhanced durability/aged adhesion in rubber matrices, such as pneumatic tires compared to either texturing or plasma polymerization alone. This process1000may eliminate brass and the associated brass corrosion issues as well as increase the life of casings for retreaded truck tires.

A cord1100having a laser micro-textured surface beneath a plasma polymerized surface may exhibit improved adhesion to a rubber matrix, such as cords used in pneumatic tires (e.g., a carcass ply, belt ply, overlay, apex, flipper, chipper, runflat insert, gum strip, etc.) in accordance with the present invention. Such improved adhesion may thereby improve any or all functional properties of a pneumatic tire. This adhesion thus enhances the performance of the pneumatic tire, even though the complexities of the structure and behavior of the pneumatic tire are such that no complete and satisfactory theory has been propounded. Temple,Mechanics of Pneumatic Tires(2005). While the fundamentals of classical composite theory are easily seen in pneumatic tire mechanics, the additional complexity introduced by the many structural components of pneumatic tires readily complicates the problem of predicting tire performance. Mayni,Composite Effects on Tire Mechanics(2005). Additionally, because of the non-linear time, frequency, and temperature behaviors of polymers and rubber, analytical design of pneumatic tires is one of the most challenging and underappreciated engineering challenges in today's industry. Mayni.

A pneumatic tire has certain essential structural elements. United States Department of Transportation,Mechanics of Pneumatic Tires, pages 207-208 (1981). Important structural elements are the carcass ply, belt ply, overlay, possibly a runflat insert, and a tread, typically made up a low modulus polymeric material, usually natural or synthetic rubber. Id. at 207 through 208.

These complexities are demonstrated by the below table of the interrelationships between tire performance and tire components.

As seen in the table, the characteristics of a carcass ply, a belt ply, an overlay, a runflat insert, and a tread may affect the other components of a pneumatic tire, leading to a number of components interrelating and interacting in such a way as to affect a group of functional properties (noise, handling, durability, comfort, high speed, and mass (possibly in two modes of operation, inflated and deflated), resulting in a completely unpredictable and complex composite. Thus, changing even one component can lead to directly improving or degrading as many as the above ten functional characteristics, in either mode, as well as altering the interaction between that one component and as many as six other structural components. Each of those six interactions may thereby indirectly improve or degrade those ten functional characteristics. Whether each of these functional characteristics is improved, degraded, or unaffected, in which mode, and by what amount, certainly would have been unpredictable without the experimentation and testing conducted by the inventors.

Thus, for example, when the structure of the carcass ply of a pneumatic tire is modified with the intent to improve one functional property of the pneumatic tire, any number of other functional properties may be unacceptably degraded. Furthermore, the interaction between the carcass ply and the belt ply, overlay, and tread may also unacceptably affect the functional properties of the pneumatic tire. A modification of the carcass ply by improving cord adhesion to the rubber matrix may not even improve that one functional property (e.g., durability) because of these complex interrelationships.

Thus, as stated above, the complexity of the interrelationships of the multiple components makes the actual result of improved adhesion of cord reinforced structures in a pneumatic tire in accordance with the present invention, impossible to predict or foresee from the infinite possible results. Only through extensive experimentation has the improved adhesion of the present invention been revealed as an excellent, albeit unexpected and unpredictable, option for a pneumatic tire.

Except where expressly indicated, all numerical quantities in this description indicating amounts of material or conditions of reaction and/or use are to be understood as modified by the word “about” in describing the broadest scope of the present invention. While the best mode for carrying out the present invention has been described in detail, those familiar with the art to which the present invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.

The description of a group or class of materials as suitable for a given purpose in connection with the present invention implies that mixtures of any two or more of the members of the group or class are suitable. Description of constituents in chemical terms refers to the constituents at the time of addition to any combination specified in the description, and does not necessarily preclude chemical interactions among constituents of the mixture once mixed. The first definition of an acronym or other abbreviation applies to all subsequent uses herein of the same abbreviation and applies mutatis mutandis to normal grammatical variations of the initially defined abbreviation. Unless expressly stated to the contrary, measurement of a property is determined by the same technique as previously or later referenced for the same property.

The previous descriptive language is of the best presently contemplated mode or modes of carrying out the present invention. This description is made for the purpose of illustrating an example of general principles of the present invention and should not be interpreted as limiting the present invention. The scope of the invention is best determined by reference to the appended claims. The reference numerals as depicted in the schematic drawings are the same as those referred to in the specification. For purposes of this application, the various examples illustrated in the figures each use a same reference numeral for similar components. The example structures may employ similar components with variations in location or quantity thereby giving rise to alternative constructions in accordance with the present invention.