Silica-coated starch

Abstract

A modified starch product comprising a quantity of particles, each particle having a starch core with an intermediate polymer coating and an outer coating of nanosilica. A method for making the modified starch product, the method comprising: combining silicate with water to form a nanosilica solution; combining the original starch with a polymer to form particles having a starch core with an intermediate polymer layer; combining the nanosilica solution with the starch particles having the intermediate polymer layer to form a suspension of the modified starch product; dewatering the suspension of the modified starch product; and drying the modified starch product to form a modified starch having particles including a starch core with an intermediate polymer coating and an outer coating of nanosilica. The rubber compound comprises a quantity of elastomer and a quantity of modified starch. The particles are substantially uniformly dispersed throughout the elastomer.

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application No. 62 / 948,376, filed December 16, 2019, the entire disclosure of which is incorporated herein by reference.

[0002]

[0002] This disclosure relates to reinforcing fillers for rubber compounds, and more particularly to modified starch fillers for rubber compounds. [Background technology]

[0003]

[0003] This section provides background information related to the present disclosure, but it is not necessarily prior art.

[0004] Starch is a carbohydrate consisting of many glucose units linked by glycosidic bonds. Starch has many advantages, such as low cost, abundant supply, and environmental friendliness. Starch is widely known for its use in the food, paper, fine chemical, and packaging industries. Starch is also a renewable material, which can reduce dependence on petroleum-based materials.

[0004]

[0005] The application of starch as a rubber filler has attracted increasing interest from the rubber industry in recent years. In particular, the use of starch in tires together with carbon black and silica can improve many properties, such as reducing tire weight, reducing rolling resistance, and improving wet grip while maintaining wear resistance. The application of starch is also attractive due to concerns about the energy consumption and environmental pollution of conventional tires.

[0005]

[0006] Starch-rubber composites are expected to be applicable not only to rubber tires but also to other types of rubber products due to their low cost, light weight, and good overall performance. For these reasons, extensive efforts have been made to develop starch-based composites, including, for example, starch biocomposites and starch-based thermoplastics obtained by blending starch with synthetic polymers, to replace one or more synthetic polymer materials or their composites.

[0006]

[0007] However, starch particles are relatively large (1-20 μm) and similarly have a low surface area compared to conventional rubber fillers such as carbon black and silica. Furthermore, starch is polar and generally exhibits reduced interaction with hydrophobic or nonpolar rubbers, such as styrene-butadiene rubber (SBR) and natural rubber (NR), compared to carbon black. Due to its low surface area and polar surface, starch interacts poorly with hydrophobic polymers. Therefore, such starch particles may not provide reinforcement when used as a filler in most rubber composites. As a result, starch-based rubber composites fail to achieve the mechanical properties required for many applications, including tires. Summary of the Invention [Problem to be solved by the invention]

[0007]

[0008] There is a continuing need for modified starch products that can be utilized in rubber compositions as reinforcing fillers in the rubber composition. Desirably, the modified starch products can provide improved performance in rubber compositions compared to unmodified starch. [Means for solving the problem]

[0008]

[0009] In accordance with the present disclosure, modified starch products have surprisingly been discovered that can be utilized in rubber compositions as reinforcing fillers therein and that can provide improved performance in rubber compositions compared to unmodified starch.

[0009]

[0010] It has been found that the hydroxyl groups on the surface of starch particles exhibit strong polarity and interact with neighboring starch particles through hydrogen bonds. The interactions between starch particles tend to cause starch to aggregate, which can lead to poor filler dispersibility in rubber compounds. Therefore, shielding the hydroxyl groups on the starch surface can reduce the hydrophilicity of starch particles and increase their hydrophobicity, thereby minimizing starch aggregation and improving filler dispersibility in rubber compounds.

[0010]

[0011] In certain embodiments, the modified starch product comprises particles having a starch core, an intermediate polymer coating, and an outer coating of nanosilica. The starch core can provide a supporting cross-base as a reinforcing filler structure. The intermediate polymer layer blocks hydrophilic hydroxyl groups on the surface of the silica core, reducing filler-filler interactions. The intermediate polymer layer also creates a polymer buffer for energy dissipation. The outer coating of nanosilica creates a shell to increase the surface area and accessibility of the modified starch product upon reaction with silanes.

[0011]

[0012] In another embodiment, a method for producing a modified starch product involves coating the surface of starch with nanosilica by an irreversible adsorption process. A silicate is mixed with water to form a nanosilica solution; the original starch is mixed with a polymer to form particles having a starch core with an intermediate polymer layer. The nanosilica solution is mixed with the starch particles having the intermediate polymer layer to form a suspension of the modified starch product. The suspension of the modified starch product can be dehydrated. The modified starch product can then be dried to form a modified starch having particles comprising a starch core with an intermediate polymer coating and an outer coating of nanosilica.

[0012]

[0013] In a further aspect, a rubber compound includes an amount of elastomer and an amount of modified starch particles, each of the particles including a starch core with an intermediate polymer coating and an outer coating of nanosilica, the particles being substantially uniformly dispersed throughout the elastomer.

[0013]

[0014] Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

[0014]

[0015] The drawings described herein are intended only to illustrate selected aspects rather than all possible implementations and are not intended to limit the scope of the present disclosure. [Brief explanation of the drawings]

[0015] [Figure 1]

[0016] FIG. 1 is a schematic diagram of a modified starch product illustrating a starch core, an intermediate polymer coating, and an outer nanosilica coating, according to one embodiment of the present disclosure. [Figure 2A]

[0017] FIG. 2 is a schematic diagram of a method for producing the modified starch product of FIG. 1 according to another embodiment of the present disclosure. [Figure 2B]

[0018] FIG. 2B is a schematic diagram of modified starch particles produced by the method shown in FIG. 2A. [Figure 3]

[0019] It includes images comparing the original starch with the modified starch products, each image taken from a scanning electron microscope and having a width of 40 micrometers, showing reduced aggregation in the modified starch products compared to the original starch. [Figure 4]

[0020] It includes images comparing the original starch and the modified starch products, each taken from a scanning electron microscope, illustrating the differences in surface morphology, including the increased surface roughness of the modified starch products compared to the original starch. [Figure 5]

[0021] 1 is a graph comparing the tensile properties of rubber compositions formulated with original starch and modified starch products. [Figure 6]

[0022] 1 is a graph comparing the modulus of rubber compositions formulated with original starch and modified starch products. [Figure 7]

[0023] 1 is a graph comparing cure curves of rubber compositions formulated with original starch and modified starch products. [Figure 8]

[0024] 1 is a graph comparing the ozone degradation properties of rubber compositions formulated with original starch and modified starch products. [Figure 9]

[0025] 1 is a graph comparing the Payne effect of rubber compositions formulated with original starch and modified starch products. [Figure 10]

[0026] 1 is a graph comparing the split adhesion properties of rubber compositions formulated with original starch and modified starch products. DETAILED DESCRIPTION OF THE INVENTION

[0016]

[0027] The following description of the technology is merely illustrative in nature of the subject matter, manufacture, and use of one or more inventions and is not intended to limit the scope, application, or use of any particular invention claimed in this application or any other application that may claim priority to this application, or in any patent issued therefrom. With regard to the disclosed methods, the order of steps presented is exemplary in nature; thus, the order of steps may be varied in various embodiments, including instances where certain steps may be performed simultaneously, unless expressly stated otherwise. As used herein, "a" and "an" mean that there is "at least one" of that item; where possible, there may be multiple such items. In describing the broadest scope of the technology, all numerical quantities herein should be understood to be modified by the word "about," and all geometric and spatial descriptions should be understood to be modified by the word "substantially," unless expressly indicated. When applied to a numerical value, "about" means that the calculation or measurement allows for some imprecision in the value (nearby; approximately, or reasonably close to; approximately). Instead, if for any reason the imprecision imparted by "about" and / or "substantially" is not understood in its ordinary sense in the art, then "about" and / or "substantially" as used herein will at least account for the variation that might result from ordinary methods of measuring or using such parameters.

[0017]

[0028] All documents cited in this detailed description, including patents, patent applications, and scientific literature, are incorporated herein by reference unless expressly stated otherwise. In the event of any conflict or ambiguity between a document incorporated by reference and this detailed description, the detailed description of the present invention will control.

[0018]

[0029] Although the open-ended term "comprising" is used herein as a synonym for non-limiting terms such as "including," "containing," or "having" to describe and claim embodiments of the present technology, embodiments can alternatively be described using more restrictive terms such as "consisting of" or "consisting essentially of." Thus, for a given embodiment that describes a material, component, or process step, the present technology also specifically includes embodiments that consist of or consist essentially of such material, component, or process step and do not include additional materials, components, or processes (in the "consisting of"), and embodiments that do not include additional materials, components, or processes that affect a critical characteristic of the embodiment, even if such additional materials, components, or processes are not explicitly set forth herein. For example, a description of a composition or process that describes elements A, B, and C specifically contemplates embodiments consisting of A, B, and C, and embodiments consisting essentially of A, B, and C, without element D, as may be described in the art, even if element D is not explicitly set forth herein as excluded.

[0019]

[0030] As referred to herein, all percentages of compositions are by weight of the total composition unless otherwise specified. The disclosure of a range includes the endpoints and encompasses all individual values ​​and further divided ranges within the entire range, unless otherwise specified. Thus, for example, a range such as "from A to B" or "from about A to about B" includes A and B. The disclosure of a value and range of values ​​for a particular parameter (e.g., amount, weight percentage, etc.) does not exclude other values ​​and ranges of values ​​useful herein. It is contemplated that two or more specific exemplary values ​​for a given parameter can define the endpoints of a range of values ​​that can be claimed for that parameter. For example, if parameter X is exemplified herein as having a value A and also exemplified herein as having a value Z, it is contemplated that parameter X can have a range of values ​​from about A to about Z. Similarly, the disclosure of two or more ranges of values ​​for a parameter (whether such ranges are nested, overlapping, or separate) is contemplated to encompass all possible combinations of value ranges that can be claimed using the endpoints of the disclosed ranges. For example, if a parameter X is exemplified herein as having a value in the range of 1 to 10, or 2 to 9, or 3 to 8, it is contemplated that the parameter X can also have other ranges of values, including 1 to 9, 1 to 8, 1 to 3, 1 to 2, 2 to 10, 2 to 8, 2 to 3, 3 to 10, 3 to 9, etc.

[0020]

[0031] When an element or layer is referred to as "resting on," "engaged with," "connected to," or "coupled to" another element or layer, it can be directly resting on, engaged with, connected to, or coupled to the other element or layer, or intervening elements or layers can be present. In contrast, when an element is referred to as "directly resting on," "directly engaged with," "directly connected to," or "directly coupled to" another element or layer, there can be no intervening elements or layers. Other terms used to describe relationships between elements (e.g., "between" vs. "directly between," "adjacent" vs. "directly adjacent," etc.) should be interpreted similarly. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0021]

[0032] Terms such as "first," "second," and "third" may be used herein to describe various elements, components, regions, layers, and / or sections, but these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms are used only to distinguish one element, component, region, layer, or section from another region, layer, or section. As used herein, terms such as "first," "second," and other numerical terms do not imply an order or sequence unless clearly indicated by context. Thus, a first element, component, region, layer, or section discussed below could also be referred to as a second element, component, region, layer, or section without departing from the teachings of the exemplary embodiments.

[0022]

[0033] The present disclosure relates to modified starch products, such as those shown in FIG. 1. The modified starch products can include discrete particles, which can be finely divided or agglomerated. The starch particles can be configured to be incorporated into or compounded into rubber compositions. Each particle can have a starch core with an intermediate polymer coating and an outer coating of nanosilica. As a non-limiting example, the modified starch product can be configured to be used as a reinforcing filler in rubber compositions for tires. Those skilled in the art can select more appropriate end uses for the modified starch products, as needed.

[0023]

[0034] The particles of the modified starch product can have a particle size of about 1 micron (1 μm) to about 10 microns (10 μm). More specifically, the particles of the modified starch product can have a particle size of about 2 microns (2 μm) to about 8 microns (8 μm). Most specifically, the particles of the modified starch product can have a particle size of about 3 microns (3 μm) to about 7 microns (7 μm). One of skill in the art can select other appropriate dimensions for the modified starch product within the scope of the present disclosure.

[0024]

[0035] The starch core can be formed from particles of original starch. The particles of original starch can have a particle size configured to allow the modified starch product to be used in a rubber composition. The original starch can have a particle size of, for example, about 1 micron (1 μm) to about 20 microns (20 μm). The original starch can be unmodified starch. The original starch can be, by way of non-limiting example, one or more of rice starch, corn starch, potato starch, and wheat starch. In a most specific embodiment, the original starch is rice starch. Those skilled in the art can employ other suitable original starches to prepare the starch core of the modified starch product, as desired.

[0025]

[0036] It should be recognized that a starch core can have multiple hydroxyl groups on its surface. When the original starch is unprocessed, the hydroxyl groups of a first starch core can undesirably interact with the hydroxyl groups of a second starch core through the formation of hydrogen bonds between the starch cores. The hydrogen bonds can cause undesirable aggregation of the starch cores defined by the original starch.

[0026]

[0037] To minimize the formation of hydrogen bonds between starch cores, intermediate polymer coatings are employed. In particular, the intermediate polymer coating of the starch core can be configured to interact with or otherwise cover the hydroxyl groups of the starch core. In other words, the intermediate polymer coating can be adapted to prevent the formation of hydrogen bonds between starch cores.

[0027]

[0038] The intermediate polymer coating can also be selected to be sufficiently reactive to interact with the nanosilica of the outer coating. The intermediate polymer layer can also improve the energy dissipation of the modified starch particles. In the most specific example, the intermediate polymer coating can be poly(diallyldimethylammonium chloride) (PDDA). Advantageously, PDDA has a high charge density. The high charge density can allow PDDA to simultaneously interact with the hydroxyl groups of the starch core and the nanosilica of the outer coating. Furthermore, the intermediate polymer layer can function as a damping layer due to the viscoelastic properties of PDDA. While PDDA has been found to be particularly advantageous, those skilled in the art can select other suitable materials with a sufficiently high charge density for the intermediate polymer coating, if desired.

[0028]

[0039] The nanosilica outer coating is disposed on the intermediate polymer coating of the modified starch product, encapsulating both the starch core and the intermediate polymer coating. The nanosilica can have a hardness that is particularly suitable for use in filler compounds, thereby improving the reinforcing effect of the filler compound. The nanosilica outer coating provides silanol groups on the outer coating of the modified starch product. The silanol groups can increase the interaction between the modified starch product and the rubber polymer in a rubber composition.

[0029]

[0040] As a non-limiting example, the outer coating of nanosilica can be formed from tetraethyl orthosilicate (TEOS). The aggregated nanosilica can have an average diameter of, for example, between about 500 nm and about 800 nm. One skilled in the art can select other suitable types and sizes of nanosilica within the scope of the present disclosure.

[0030]

[0041] Referring to Figures 3 and 4, scanning electron microscopy was used to image the particles of the original starch and the modified starch product. Figure 3 shows the aggregation of the original starch and the modified starch product, revealing that the modified starch product exhibits reduced particle aggregation compared to the original starch. The addition of the intermediate polymer coating and the nanosilica outer coating disrupts the structure of the original starch aggregates. As shown in Figure 4, the nanosilica outer coating increases the surface area compared to that of the raw starch. Therefore, the nanosilica outer coating increases the accessibility of the modified starch product particles for reaction with rubber polymers.

[0031]

[0042] The present disclosure includes a method for producing a modified starch product, for example, as shown in FIG. 2. The first step of the method can be the synthesis of nanosilica. A silicate can be introduced into a solution to form nanosilica. In a more specific embodiment, the silicate can be tetraethyl orthosilicate (TEOS). TEOS can be mixed with, by way of non-limiting example, isopropyl alcohol, deionized water, and ammonium hydroxide to form a nanosilica solution. The nanosilica solution can be stirred for a predetermined period of time. For example, the predetermined period of time can be about 8 to about 12 hours. One skilled in the art can select other suitable silica sources and additional materials to form the nanosilica solution, as needed.

[0032]

[0043] The second step of the method can be to form an intermediate polymer coating on the original starch. The original starch can be mixed with a polymer having a high charge density. As a non-limiting example, the polymer can be PDDA. More specifically, the original starch and PDDA can be mixed with NaCl and deionized water to form a suspension of starch core particles with an intermediate polymer layer. The suspension of surface-modified starch can be stirred for a predetermined time, for example, 30 minutes. The suspension of surface-modified starch can then be centrifuged to collect the starch core particles with an intermediate polymer layer.

[0033]

[0044] The third step of the method can be forming an outer coating of nanosilica on the intermediate polymer coating. The particles comprising the starch core with the intermediate polymer layer formed thereon from the second step of the method can be mixed with the nanosilica solution formed in the first step. The resulting solution can include particles of modified starch product. The solution of particles of modified starch product can be stirred for a predetermined time, for example, about 8 hours to about 12 hours.

[0034]

[0045] The solution of modified starch product particles can be filtered. The modified starch product can be rinsed and dried. The rinsing solution can include a 1:1 solution of isopropyl alcohol and deionized water. For example, the modified starch product can be dried in an oven at 50°C for a predetermined period of time to remove residual water and solvent.

[0035]

[0046] The present disclosure further includes a rubber composition for a tire component comprising the modified starch product. More specifically, the modified starch product can be used as a filler in the rubber composition for a tire component. By way of non-limiting example, the tire component can be a tire sidewall, a tire tread cap, or a tire base. Those skilled in the art can utilize the rubber composition for a tire component in additional tire components as needed.

[0036]

[0047] A rubber composition for a tire component can include an amount of elastomer and an amount of modified starch, the modified starch comprising particles having a starch core with an intermediate polymer coating and an outer coating of nanosilica, as described above. The particles can be dispersed substantially uniformly throughout the elastomer, for example, by conventional mixing operations.

[0037]

[0048] The modified starch product may be present in the rubber composition in an amount between 0 and 20 phr, more particularly between 5 and 15 phr, and most particularly 10 phr. Other suitable concentrations of the modified starch product in the rubber composition may also be selected, if desired.

[0038]

[0049] The rubber composition may further include a silane, more specifically, a polysulfide-type silane coupling agent for rubber applications. As a non-limiting example, the silane may be bis-3-triethoxysilylpropyltetrasulfide (TESPT). The silane may be added to react with the silanol groups of the outer coating of the nanosilica. The silane may be present in the rubber composition in an amount between 0.0 phr and 1.0 phr, more specifically between 0.5 phr and 0.9 phr, and most specifically 0.7 phr. Other suitable concentrations of the silane may also be selected as needed. Those skilled in the art may select other suitable types of silane coupling agents and their concentrations within the scope of the present disclosure.

[0039]

[0050] The rubber composition of the present disclosure can be compounded by various methods known in the rubber compounding art, for example, by mixing the elastomer and modified starch product with various commonly used additive materials. For example, the additive materials can include curing aids such as sulfur, activators, retarders and accelerators, processing additives such as oils, resins such as tackifying resins, plasticizers, non-carbon fillers, pigments, fatty acids, zinc oxide, waxes, antioxidants and antiozonants, peptizers, and reinforcing materials. Other suitable additives for rubber compositions can also be used as needed. Depending on the intended use of the rubber composition, conventional additives can be selected and used in conventional amounts in the rubber composition of the present invention.

[0040]

[0051] The elastomer, modified starch product, and additive materials are dispersed substantially uniformly throughout the rubber composition prior to extrusion or molding, for example, by conventional mixing. It should be understood that substantially uniform dispersion of the elastomer and modified starch product can be facilitated by thorough mixing, and the ability to perform such mixing is within the capabilities of one skilled in the art.

[0041]

[0052] The present disclosure also includes articles comprising the rubber compositions. It should be recognized that the rubber compositions can be extruded, molded, or otherwise formed into a desired shape and cured by the application of heat and / or pressure. In a most specific example, as previously described, the rubber compositions can be used in the tread of a tire.

[0042]

[0053] The following examples are offered by way of illustration, not by way of limitation, of the present invention. [Example]

[0043]

[0054] Exemplary aspects of the present technology are provided with reference to several figures attached hereto.

[0055] The rubber compositions of the present disclosure were prepared for testing in a laboratory-sized rubber mixer according to conventional two-pass rubber mixing techniques. The rubber compositions were selected to evaluate the general effect of modified starch products on the physicochemical properties of the rubber compositions. The formulations of the experimental rubber compositions containing modified starch are shown in Table 1 below, along with a comparison containing the original starch.

[0044] [Table 1]

[0045]

[0056] The rubber compositions shown in Table 1 were cured using standard vulcanization techniques and tested for various processing and physicochemical properties.

[0057] Referring to Figures 5-6, the tensile properties of the rubber compound containing the original starch in Table 1 and the rubber compound containing the modified starch in Table 1 were tested and compared. The rubber compound containing the modified starch exhibits improved tensile properties compared to the rubber compound containing the original starch. Therefore, it can be concluded that the rubber compound containing the modified starch functions as a reinforcing filler in the compound.

[0046]

[0058] With continued reference to Figure 6, the moduli were calculated for the original starch rubber compound and the modified starch rubber compound at strains of 100%, 200%, and 300%. It was found that the difference in modulus between the two compounds increased as strain increased. For example, at 100% strain, the two compounds exhibited similar moduli, but at 300% strain, the modified starch compound exhibited a modulus 15% higher than the original starch compound. Thus, the modified starch rubber compound exhibited a higher modulus than the original starch rubber compound, further indicating the reinforcing effect of the modified starch product when used as a filler.

[0047]

[0059] The cure curves for the original starch rubber compound and the modified starch rubber compound were calculated and compared, as shown in Figure 7. The original starch rubber compound and the modified starch rubber compound exhibited similar cure curves.

[0048]

[0060] Referring to Figure 8, the fatigue properties of the original starch rubber compound and the modified starch compound were investigated. More specifically, the original starch rubber compound and the modified starch compound were tested after storage under ozone conditions. Since ozone is known to be an important factor in rubber fatigue, this can indirectly reflect the fatigue properties of the compound. Therefore, a compound with a higher ozone dynamic load has better anti-fatigue properties.

[0049]

[0061] After exposing the compounds to ozone for 0, 24, 48, 72, and 96 hours, the maximum load was calculated for each of the original starch rubber compound and the modified starch compound. It was found that the modified starch compound had a higher load than the original starch compound. This result is believed to be due to the coupling of the surface silanol groups in the modified starch compound with the polymer, which can reduce the potential failure points induced in the rubber. Thus, the anti-fatigue properties of the rubber are effectively improved.

[0050]

[0062] As shown in Figure 9, the interactions of the original starch rubber compound and the modified starch compound with each of the polymers in the rubber compound were investigated. The Payne effect is a common tool for investigating filler-polymer interactions. The Payne effect for the same rubber system can be calculated semi-quantitatively using the equation ΔG' = ΔG' (0.1%) - ΔG' (20%). The modified starch compound was shown to exhibit a lower ΔG' than the original starch compound, thus indicating a stronger filler / elastomer interaction.

[0051]

[0063] Referring to Figure 10, split adhesion tests were performed on the original starch rubber compound and the modified starch compound. The modified starch compound exhibited higher split adhesion than the original starch compound. It is believed that the improved split adhesion may be related to energy dissipation in the intermediate polymer coating. Due to the viscoelasticity of the intermediate polymer, it can function as a damping layer between the modified starch product and the elastomer of the rubber composition.

[0052]

[0064] Advantageously, the modified starch products are hydrophobic in the presence of a silane coupling agent and, therefore, can be utilized as a reinforcing filler in rubber compositions. Furthermore, the modified starch products can provide improved performance in rubber compositions, especially when compared to unmodified starch.

[0053]

[0065] Exemplary embodiments have been described so that this disclosure will be thorough and its scope will be fully conveyed to those skilled in the art. Numerous specific details, such as examples of particular components, devices, and methods, are described to provide a thorough understanding of the embodiments of the present disclosure. It will be apparent to those skilled in the art that specific details need not be employed, that the exemplary embodiments can be embodied in many different forms, and that neither should be construed as limiting the scope of the present disclosure. In some exemplary embodiments, well-known processes, well-known device structures, and well-known techniques have not been described in detail. Equivalent changes, modifications, and variations of some embodiments, materials, compositions, and methods can be made within the scope of the present technology and achieve substantially similar results.

Claims

1. A modified starch product for rubber formulations, comprising a plurality of particles, each particle comprising a starch core, an intermediate polymer coating and an outer coating comprising nanosilica, the intermediate polymer coating being selected to have a charge density that enables it to simultaneously interact with the hydroxyl groups of the starch core and the nanosilica of the outer coating.

2. 10. The modified starch product of claim 1, wherein the modified starch is produced by combining a raw starch with silica.

3. 3. The modified starch product of claim 2, wherein the nanosilica comprises tetraethyl orthosilicate.

4. 10. The modified starch product of claim 1, wherein the intermediate polymer coating comprises poly(diallyldimethylammonium chloride).

5. 10. The modified starch product of claim 1, wherein the starch core comprises a member selected from the group consisting of rice starch, corn starch, potato starch, wheat starch, and combinations thereof.

6. A method for producing a modified starch product for a rubber compound, comprising: combining silicate with water to form a nanosilica-containing solution; blending the original starch with a polymer to form particles, each particle having a starch core and an intermediate polymer coating; and combining the nanosilica-containing solution with the particles to form a suspension of modified starch product particles; Including, wherein each modified starch product particle comprises a starch core, an intermediate polymer coating, and an outer coating comprising nanosilica, and wherein the intermediate polymer coating is selected to have a charge density capable of simultaneously interacting with the hydroxyl groups of the starch core and the nanosilica of the outer coating. method.

7. dewatering the suspension of modified starch product particles; and drying the modified starch product particles to form the modified starch product. The method of claim 6 further comprising:

8. 7. The method of claim 6, wherein the silicate is tetraethyl orthosilicate.

9. 7. The method of claim 6, wherein the silicate is further combined with isopropyl alcohol, ammonium hydroxide, and deionized water to form the nanosilica-containing solution.

10. The method of claim 6 wherein the polymer is poly(diallyldimethylammonium chloride).

11. an amount of elastomer; and A quantity of modified starch granules, each modified starch granule comprising a starch core, a middle polymer coating, and an outer coating comprising nanosilica. A rubber compound comprising: the particles are substantially uniformly dispersed throughout the elastomer; The rubber compound.

12. The rubber compound of claim 11 further comprising a silane.

13. The rubber compound of claim 12, wherein the silane comprises a polysulfide-type silane coupling agent.

14. The rubber compound of claim 12, wherein the silane comprises bis-3 triethoxysilylpropyl tetrasulfide.

15. An article comprising the rubber compound of claim 11.

16. A tire comprising a tire sidewall comprising the rubber compound of claim 11.

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