High cavity nano starch and high aging-resistant rubber material based on same and preparation thereof

Abstract

The application belongs to the technical field of modified rubber, and discloses a high-cavity nano starch, a high-aging-resistant rubber material based on the high-cavity nano starch and a preparation method of the high-cavity nano starch. The preparation method of the high-cavity nano starch comprises the following steps: sequentially performing gelatinization pretreatment and single-helix structure modification treatment on starch, and then performing homogenization treatment in an ultrahigh-pressure nano material preparation dispersing machine to obtain the high-cavity nano starch. The method can prepare a nano starch emulsion with high stability, the starch has a high-cavity structure and a nano-level particle size, and the dispersibility of the starch is significantly improved when the starch is mixed with natural latex. The high-cavity nano starch can be applied to rubber reinforcement, and the obtained rubber material has significantly improved tensile strength and tear strength, the tensile strength is increased by 34%, the tear strength is increased by 58%, and the rubber material has excellent aging resistance without adding an anti-aging agent, so that the problems of uneven rubber compound, increased defects, discoloration and environmental pollution caused by the addition of the anti-aging agent in the existing rubber are solved.

Description

Technical Field

[0001] This invention belongs to the field of modified rubber technology, and specifically relates to a high-cavity nano-starch and a high-aging-resistant rubber material based thereon and its preparation. Background Technology

[0002] Natural rubber possesses excellent comprehensive properties and processing performance, including wear resistance, high elasticity, and ease of processing, making it widely used in industrial products such as tires, conveyor belts, and seals. However, natural rubber and its products are susceptible to aging during processing, storage, and use due to environmental factors such as heat, oxygen, ozone, and humidity. Oxidation is one of the main causes of natural rubber aging. The numerous carbon-carbon double bond molecular chains in natural rubber readily produce free radicals under the influence of heat and oxygen. These free radicals continue to react with oxygen, causing the rubber molecular backbone to break and degrade. Simultaneously, under the influence of free radicals, residual free sulfur in the sulfur vulcanization system continues to crosslink or desulfurizes polysulfide bonds, generating more monosulfide and disulfide bonds. This leads to shorter molecular chain lengths and increased crosslinking density, resulting in the material becoming brittle, hard, and losing elasticity. Improving the aging resistance of natural rubber is crucial for extending its service life and enhancing its safety. Existing technologies mainly improve the aging resistance of natural rubber by adding antioxidants and improving the vulcanization system. However, these methods often have a negative impact on the original properties of the rubber. For example, antioxidants are difficult to disperse evenly during the mixing process, resulting in large differences and instability in rubber properties, as well as causing discoloration of the rubber compound and environmental pollution.

[0003] Starch has many advantages, including wide availability, renewability, cost-effectiveness, and minimal environmental impact. In particular, its abundant active hydroxyl groups show great potential for capturing and neutralizing free radicals, making it a novel green antioxidant for rubber. However, the large particle size, high crystallinity, and tendency to agglomerate of primary starch particles make it difficult to disperse evenly in the rubber matrix, resulting in poor anti-aging and reinforcing effects. Summary of the Invention

[0004] In order to overcome the shortcomings and deficiencies of the prior art, the primary objective of this invention is to provide a method for preparing high-cavity nano starch.

[0005] The method of the present invention first processes starch to obtain modified starch with a single helical structure, and then uses an ultra-high pressure nanomaterial dispersing machine to homogenize and disperse the processed starch to prepare nanoscale high-cavity nano starch.

[0006] The preparation method of this invention is green and environmentally friendly, has specific reaction characteristics, and is highly operable. It is inspiring for providing new rubber fillers and the preparation and application of green rubber.

[0007] Another object of the present invention is to provide high-cavity nano-starch prepared by the above method.

[0008] Another object of the present invention is to provide a natural latex / starch composite based on the above-mentioned high-cavity nano starch.

[0009] Another object of the present invention is to provide applications of the above-mentioned high-cavity nano starch, particularly in rubber modification.

[0010] Another object of the present invention is to provide a highly aging-resistant rubber material based on the above-mentioned high-cavity nano-starch. The natural rubber / starch composite material prepared by blending the high-cavity nano-starch of the present invention with natural latex exhibits significantly improved aging resistance.

[0011] The objective of this invention is achieved through the following solution:

[0012] A method for preparing high-cavity nano starch includes subjecting starch to gelatinization pretreatment, single-helix structure modification treatment, and homogenization treatment in an ultra-high pressure nanomaterial preparation disperser to obtain high-cavity nano starch.

[0013] In the preparation method of the present invention, the gelatinization pretreatment can be carried out using conventional gelatinization processes, such as preparing a starch suspension with a concentration of 5-25 wt% using phosphate buffer and gelatinizing it at 80-100℃ for 0.5-1.5 h.

[0014] Furthermore, the phosphate buffer solution has a pH of 5.

[0015] In the preparation method of the present invention, the single-helix structure modification treatment may include enzymatic hydrolysis, acid hydrolysis modification, or oxidative modification treatment.

[0016] Furthermore, the enzymatic hydrolysis and acid hydrolysis modification treatment includes the following steps: after starch gelatinization pretreatment, amylase is added, followed by incubation and enzymatic hydrolysis, followed by heating and inactivation, followed by addition of acid solution and heating for acid hydrolysis, to obtain modified starch with a single helical structure after enzymatic hydrolysis and acid hydrolysis.

[0017] Furthermore, the amount of amylase used can be 5-30 ASPU / g starch.

[0018] Furthermore, the incubation enzymatic hydrolysis can be carried out at 55-65℃ for 4-8 hours.

[0019] Furthermore, the amylase can be any amylase commonly used in the art, such as pullulanase, α-glucan phosphorylase, etc.

[0020] Furthermore, the molar ratio of the acid solution to starch can be 0.25:1 to 1:1. The acid solution can be hydrochloric acid, sulfuric acid, phosphoric acid, etc., and the concentration of the acid solution can be 1-3 mol / L.

[0021] Furthermore, the heating and acid hydrolysis can be carried out at 70-90℃ for 1-6 hours.

[0022] Furthermore, the acid hydrolysate can be neutralized with alkali and washed with water to obtain the treated starch.

[0023] Furthermore, the oxidative modification treatment involves oxidizing the pretreated starch with copper sulfate and hydrogen peroxide under acidic conditions.

[0024] Furthermore, the amount of copper sulfate used can be 1-3‰ of the starch mass.

[0025] Furthermore, the molar ratio of hydrogen peroxide to starch used can be 0.15:1-0.5:1.

[0026] Furthermore, the acidic conditions refer to a system pH of 5.8-6.2.

[0027] Furthermore, the oxidation reaction can be carried out at 25-50°C for 8-24 hours.

[0028] Furthermore, after the reaction was completed, the starch was precipitated with anhydrous ethanol and then washed with water to obtain the treated starch.

[0029] In the preparation method of this invention, before homogenization, the treated starch is diluted with water to a dispersion with a mass concentration of 0.5-2.5 wt%. Homogenization can be performed 15-25 times, until the dispersion emits a blue glow.

[0030] In this invention, amylase is used to enzymatically remove the branched chains of starch, while acid hydrolysis is used to destroy the amorphous and residual crystalline regions of the enzymatically hydrolyzed starch, shortening the molecular chain length, reducing the molecular weight and relative crystallinity, and transforming the starch molecular chain from a double helix to a single helix structure, forming high cavities including hydroxyl groups, thus enhancing the starch's ability to capture free radicals; or, a Fenton-like reagent is used to oxidize the starch, causing the starch molecular chains to break and recombine, and introducing new functional groups on the molecular chains to increase the steric hindrance between molecular chains, so that the single molecular chain helix forms a cavity structure, enhancing the ability of oxidized starch to capture free radicals; then, an ultra-high pressure nanomaterial dispersant is used for homogenization to further reduce the size of the high-cavity starch particles, obtaining a highly stable nano-starch emulsion.

[0031] This invention provides a high-cavity nano-starch prepared by the above method. The preparation method of this invention involves gelatinization pretreatment, single-helix structure modification treatment, and then homogenization treatment to prepare a highly stable nano-starch emulsion. The starch in this emulsion has a high-cavity structure and a particle size reaching the nanometer scale. When mixed with natural latex, it exhibits significantly improved dispersibility.

[0032] This invention also provides the application of the above-mentioned high-cavity nano starch in rubber modification.

[0033] This invention also provides a natural latex / starch composite based on the aforementioned high-cavity nano-starch. The latex / starch composite is obtained by mixing a high-cavity nano-starch dispersion with natural latex and then co-precipitating the mixture.

[0034] Furthermore, the starch content in the natural latex / starch composite can be 1-30 wt%.

[0035] Furthermore, the mass concentration of the high-cavity micro / nano starch dispersion can be 0.5-2.5 wt%. The high-cavity nano starch dispersion is obtained by the above preparation method.

[0036] Furthermore, the solid content of the natural latex can be 50-70%.

[0037] Furthermore, co-precipitation is a conventional process in this field. Continuous stirring ensures uniform mixing of the high-cavity nano-starch and latex, followed by demulsification and sedimentation. The settled solids are then washed with water and dried to obtain the latex / starch composite. The stirring time can be 1-3 hours. Vacuum drying can be performed at 50°C.

[0038] In the above preparation method, the quality of the dispersion and natural latex used can be determined first based on the formula, the concentration of the dispersion, and the solid content of the natural latex, and then the preparation can be carried out.

[0039] The present invention also provides a high-aging-resistant rubber material based on the above-mentioned high-cavity nano starch, wherein the composition contains 1-30 wt% of the above-mentioned high-cavity nano starch.

[0040] The present invention also provides a method for preparing the above-mentioned high aging-resistant rubber material, which involves mixing high-cavity nano starch dispersion and natural latex, co-coagulating to obtain a latex / starch composite; and then using traditional rubber processing technology to mix with rubber additives to prepare a natural rubber / starch composite material.

[0041] Furthermore, the rubber additives can be conventional additives, such as stearic acid, zinc oxide, accelerators, and sulfur.

[0042] The rubber material prepared by the present invention using high-cavity nano starch blending has significantly improved tensile strength and tear strength, with tensile strength increased by 34% and tear strength increased by 58%, and it has excellent aging resistance without the addition of antioxidants.

[0043] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0044] (1) The high-cavity nano starch provided by the present invention has low molecular weight and low relative crystallinity. Its molecular chain has a single helical structure and high cavity with hydroxyl groups, and has excellent free radical scavenging ability.

[0045] (2) The high-cavity nano starch of the present invention has excellent dispersibility and compatibility in the rubber matrix. The natural rubber / starch composite material prepared by blending it with natural latex has significantly improved aging resistance, tensile strength and tear strength. Attached Figure Description

[0046] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This is a scanning electron microscope image of the high-cavity nano-starch from Example 1.

[0048] Figure 2 This is a scanning electron microscope image of the high-cavity nano-starch in Example 4.

[0049] Figure 3 The image shows the X-ray diffraction curve of the high-cavity nano starch in Example 1.

[0050] Figure 4 This is a photograph of the roller sticking during the mixing process of the natural latex / pure starch compound in Comparative Example 1. Detailed Implementation

[0051] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto. It should be noted that the embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Furthermore, it should be understood that after reading the teachings of the present invention, those skilled in the art can make some non-essential improvements and adjustments based on the above content of the present invention, and these equivalent forms also fall within the scope defined by the appended claims. The raw materials involved in the present invention can all be purchased from conventional commercial channels. For process parameters not specifically specified, conventional techniques can be referred to. The amounts of each component are expressed in parts by mass or parts by volume, in g or mL.

[0052] The raw materials used in the following examples and comparative examples are as follows:

[0053] Tapioca starch: food grade, Shandong Hengren Industry & Trade Co., Ltd.

[0054] Natural latex: 60% solids content, Chinese Academy of Tropical Agricultural Sciences;

[0055] Pullulanase: P299007, Aladdin.

[0056] Example 1

[0057] (1) Preparation of high-cavity nano starch

[0058] 100 parts by weight of starch were added to 1000 parts by volume of phosphate buffer solution with pH=5.0. The mixture was gelatinized in a 100℃ water bath at 300 rpm for 0.5 h. After complete gelatinization, it was removed and cooled to 58℃. Pullulanase solution was added at a rate of 5 ASPU / g starch. The starch paste was then incubated in a 58℃ water bath for 8 h of enzymatic hydrolysis. After the enzymatic hydrolysis was completed, the water bath temperature was raised to 100℃ and heated for 30 min to inactivate the enzyme and terminate the reaction. Then, 150 parts by volume of 1 mol / L hydrochloric acid was added, and the mixture was hydrolyzed in a 70℃ water bath for 3 h. After the reaction, the mixture was neutralized, washed with water, diluted, and dispersed in deionized water (solid content 1%). The dispersion was homogenized 18 times in an ultra-high pressure nanomaterial dispersant to obtain a high-cavity nano-starch dispersion. The prepared high-cavity nano-starch was then observed. Figure 1 The image shows a scanning electron microscope (SEM) image of the high-cavity nano-starch from Example 1. As can be seen from the image, its particle size reaches the nanometer scale and it is well dispersed. Figure 3 The image shows the X-ray diffraction curve of the high-cavity nano-starch in Example 1. As can be seen from the figure, the starch transforms from A-type crystals with a double-helix structure to V-type high-cavity crystals with a single-helix structure. h It exhibits a crystallization pattern, with a significantly reduced relative crystallinity.

[0059] (2) Preparation of natural latex / starch complex

[0060] 100 parts by weight of 1 wt% high-cavity nano starch dispersion and 33.4 parts by weight of natural latex with a solid content of 60% were mechanically stirred at 500 rpm for 1 hour at room temperature to ensure that the starch was fully and uniformly dispersed in the natural latex. Then, the emulsion was broken, the mixture was allowed to settle, washed with water, and dried in a vacuum oven at 50°C for 24 hours to obtain a natural latex / starch composite.

[0061] Example 2

[0062] (1) Preparation of high-cavity nano starch

[0063] 100 parts by weight of starch were added to 1000 parts by volume of phosphate buffer solution with pH=5.0. The mixture was gelatinized in a 90°C water bath at 350 rpm for 1 hour. After complete gelatinization, the mixture was removed and cooled to 58°C. Pullulanase solution was added at a concentration of 10 ASPU / g starch. The starch paste was then placed in a 59°C water bath for 6 hours of enzymatic hydrolysis. After the enzymatic hydrolysis was completed, the water bath temperature was raised to 100°C and heated for 30 minutes to inactivate the enzyme and terminate the reaction. Then, 150 parts by volume of 2 mol / L hydrochloric acid was added, and the mixture was hydrolyzed in a 75°C water bath for 2 hours. After the reaction was completed, the mixture was neutralized, washed with water, diluted, and dispersed in deionized water (solid content 1.5%). The mixture was homogenized 16 times in an ultra-high pressure nanomaterial preparation disperser to prepare a high-cavity nano-starch dispersion.

[0064] (2) Preparation of natural latex / starch complex

[0065] 120 parts by weight of 1.5 wt% high-cavity nano starch dispersion and 33.4 parts by weight of natural latex with a solid content of 60% were mechanically stirred at 500 rpm for 1 hour at room temperature to ensure that the starch was fully and uniformly dispersed in the natural latex. Then, the emulsion was broken, the mixture was allowed to settle, washed with water, and dried in a vacuum oven at 50°C for 24 hours to obtain a natural latex / starch composite.

[0066] Example 3

[0067] (1) Preparation of high-cavity nano starch

[0068] 100 parts by weight of starch were added to 1000 parts by volume of phosphate buffer solution with pH=5.0. The mixture was gelatinized in an 85°C water bath at 400 rpm for 1 hour. After complete gelatinization, the mixture was removed and cooled to 58°C. Pullulanase solution was added at a concentration of 15 ASPU / g starch. The starch paste was then placed in a 60°C water bath for 6 hours of enzymatic hydrolysis. After the enzymatic hydrolysis was completed, the water bath temperature was raised to 100°C and heated for 30 minutes to inactivate the enzyme and terminate the reaction. Then, 150 parts by volume of 3 mol / L hydrochloric acid was added, and the mixture was hydrolyzed in an 80°C water bath for 1 hour. After the reaction was completed, the mixture was neutralized, washed with water, diluted, and dispersed in deionized water (solid content of 2%). The mixture was homogenized 20 times in an ultra-high pressure nanomaterial preparation disperser to prepare a high-cavity nano-starch dispersion.

[0069] (2) Preparation of natural latex / starch complex

[0070] 150 parts by weight of 2 wt% high-cavity nano starch dispersion and 33.4 parts by weight of 60% solid content natural latex were mechanically stirred at 500 rpm for 1 h at room temperature to ensure that the starch was fully and uniformly dispersed in the natural latex. Then, the emulsion was broken, the mixture was allowed to settle, washed with water, and dried in a vacuum oven at 50℃ for 24 h to obtain a natural latex / starch composite.

[0071] Example 4

[0072] (1) Preparation of high-cavity nano starch

[0073] 100 parts by weight of starch were added to 1000 parts by volume of phosphate buffer solution with pH=5.0. The mixture was gelatinized for 0.5 h in an 85°C water bath with stirring at 350 rpm. After complete gelatinization, the mixture was removed and cooled to room temperature. The pH was adjusted to 5.8 with 0.5 mol / L sodium hydroxide solution. Then, 1 part by weight of copper sulfate and 11 parts by weight of 30% hydrogen peroxide solution were added. The mixture was then oxidized for 12 h in a 25°C water bath with mechanical stirring at 300 rpm. After the reaction, the mixture was precipitated with anhydrous ethanol, washed with water, and then diluted and dispersed in deionized water (solid content 1%). The dispersion was then homogenized 16 times in an ultra-high pressure nanomaterial dispersant to obtain a high-cavity nano-starch dispersion. The prepared high-cavity nano-starch was observed. Figure 2 The image shows a scanning electron microscope (SEM) image of the high-cavity nano-starch from Example 4. As can be seen from the image, its particle size reaches the nanometer scale and it is well dispersed.

[0074] (2) Preparation of natural latex / starch complex

[0075] 100 parts by weight of 1 wt% high-cavity nano starch dispersion and 33.4 parts by weight of natural latex with a solid content of 60% were mechanically stirred at 500 rpm for 1 hour at room temperature to ensure that the starch was fully and uniformly dispersed in the natural latex. Then, the emulsion was broken, the mixture was allowed to settle, washed with water, and dried in a vacuum oven at 50°C for 24 hours to obtain a natural latex / starch composite.

[0076] Example 5

[0077] (1) Preparation of high-cavity nano starch

[0078] 100 parts by mass of starch were added to 1000 parts by volume of phosphate buffer solution with pH=5.0. The mixture was gelatinized in an 85°C water bath with stirring at 350 rpm for 0.5 h. After complete gelatinization, the mixture was removed and cooled to 30°C. The pH was adjusted to 6.0 with 0.5 mol / L sodium hydroxide solution. Then, 2 parts by mass of copper sulfate and 15 parts by mass of 30% hydrogen peroxide solution were added. The mixture was oxidized in a 30°C water bath with mechanical stirring at 300 rpm for 18 h. After the reaction was completed, the mixture was precipitated with anhydrous ethanol and washed with water. The mixture was then diluted and dispersed in deionized water (solid content of 1.5%). The mixture was then homogenized 18 times in an ultra-high pressure nanomaterial preparation disperser to obtain a high-cavity nano-starch dispersion.

[0079] (2) Preparation of natural latex / starch complex

[0080] 120 parts by weight of 1.5 wt% high-cavity nano starch dispersion and 33.4 parts by weight of natural latex with a solid content of 60% were mechanically stirred at 500 rpm for 1 hour at room temperature to ensure that the starch was fully and uniformly dispersed in the natural latex. Then, the emulsion was broken, the mixture was allowed to settle, washed with water, and dried in a vacuum oven at 50°C for 24 hours to obtain a natural latex / starch composite.

[0081] Example 6

[0082] (1) Preparation of high-cavity nano starch

[0083] 100 parts by mass of starch were added to 1000 parts by volume of phosphate buffer solution with pH=5.0, and gelatinized for 0.5 h in an 85°C water bath with stirring at 350 rpm. After complete gelatinization, the mixture was removed and cooled to 45°C. The pH was adjusted to 6.2 with 0.5 mol / L sodium hydroxide solution. Then, 3 parts by mass of copper sulfate and 20 parts by mass of 30% hydrogen peroxide solution were added. The mixture was then oxidized for 24 h in a 45°C water bath with mechanical stirring at 300 rpm. After the reaction was completed, the mixture was precipitated with anhydrous ethanol, washed with water, and then diluted and dispersed in deionized water (solid content of 2%). The mixture was then homogenized 20 times in an ultra-high pressure nanomaterial preparation disperser to obtain a high-cavity nano-starch dispersion.

[0084] (2) Preparation of natural latex / starch complex

[0085] 150 parts by weight of 2 wt% high-cavity nano starch dispersion and 33.4 parts by weight of 60% solid content natural latex were mechanically stirred at 500 rpm for 1 h at room temperature to ensure that the starch was fully and uniformly dispersed in the natural latex. Then, the emulsion was broken, the mixture was allowed to settle, washed with water, and dried in a vacuum oven at 50℃ for 24 h to obtain a natural latex / starch composite.

[0086] Comparative Example 1

[0087] Two parts by weight of pure starch and 33.4 parts by weight of natural latex with a solid content were mechanically stirred at 500 rpm for 1 hour at room temperature. Then, the mixture was broken up, settled, washed with water, and dried in a vacuum oven at 50°C for 24 hours to obtain a natural latex / pure starch composite. When this composite was mixed with rubber additives using traditional rubber processing technology, it was found that the rubber compound adhered tightly to the rollers, making the mixing operation difficult. Figure 4 This is a photograph of the natural latex / pure starch composite sticking to the rollers during the mixing process in Comparative Example 1.

[0088] Comparative Example 2

[0089] 33.4 parts by weight of natural latex with a solid content of 60% were mechanically stirred at 500 rpm for 1 hour at room temperature, then the latex was broken, settled, washed with water, and dried in a vacuum oven at 50°C for 24 hours to obtain a pure natural latex sample.

[0090] The natural latex / starch composites obtained in Examples 1-6 and the pure natural latex sample obtained in Comparative Example 2 were first plasticized at room temperature under cooling water. Then, they were mixed in the order of adding stearic acid, zinc oxide, accelerator, and sulfur. Finally, the mixed rubber was thinly spun 10 times and sheeted. After the mixed rubber was left to stand overnight, the vulcanization characteristic curve was measured using a vulcanizing apparatus, and it was vulcanized and molded using a flat vulcanizing machine at 143℃ × Tc90. Rubber samples were prepared. The vulcanization formula (dry basis) was: 100 parts by weight of natural latex / composite material, 0.4 parts by weight of stearic acid, 1.0 parts by weight of zinc oxide, 0.3 parts by weight of accelerator, and 0.3 parts by weight of sulfur. 0.2 parts by weight of antioxidant were also added to the pure natural latex sample.

[0091] The rubber samples prepared above were aged in a thermo-oxidative aging oven at 70℃ for 72 hours according to GB / T 13939-2014. Dumbbell-shaped tensile specimens and uncut right-angled specimens were cut according to GB / T 528-2009 and GB / T 529-2008 to test tensile properties and tear strength.

[0092] The tensile strength, elongation at break, 100% modulus, 300% modulus, and tear strength of the samples before and after aging were statistically analyzed. The statistical results before aging are shown in Table 1, and the statistical results after aging are shown in Table 2.

[0093] Table 1

[0094]

[0095] Table 2

[0096]

[0097] As shown in the table, the natural rubber reinforced with the hollow nano-starch of this invention exhibits significantly improved tensile strength and tear strength. Furthermore, the natural rubber reinforced with the hollow nano-starch of this invention demonstrates superior aging resistance without the addition of antioxidants. This solves the problems of uneven rubber material, increased defects, discoloration, and environmental pollution caused by the addition of existing antioxidants, while achieving better aging resistance.

[0098] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing high-cavity nano-starch, characterized in that, The process includes pretreating starch with gelatinization, adding amylase after gelatinization, incubating for enzymatic hydrolysis, inactivating the amylase by heating, adding acid solution, and then heating for acid hydrolysis to obtain modified starch with a single helical structure after enzymatic and acid hydrolysis; diluting the modified starch with water to a mass concentration of 0.5-2.5 wt% dispersion, and homogenizing it in an ultra-high pressure nanomaterial preparation disperser to obtain high-cavity nano-starch; the high-cavity nano-starch has a V-shaped crystalline structure with a single helical structure. The amount of amylase used is 5-30 ASPU / g starch; the incubation enzymatic hydrolysis is carried out at 55-65℃ for 4-8 hours; the molar ratio of acid solution to starch is 0.25:1-1:1; the heating acid hydrolysis is carried out at 70-90℃ for 1-6 hours.

2. The preparation method according to claim 1, characterized in that, The gelatinization pretreatment involves preparing a starch suspension with a concentration of 5-25 wt% using phosphate buffer and gelatinizing it at 80-100℃ for 0.5-1.5 h.

3. The preparation method according to claim 1, characterized in that, The homogenization process is repeated 15-25 times.

4. The application of the high-cavity nano-starch prepared by the method according to any one of claims 1-3 in rubber modification.

5. The application according to claim 4, characterized in that... The rubber component contains 1-30 wt% of high-cavity nano-starch prepared by the method according to any one of claims 1-3.

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