Preparation method of modified aramid pulp reinforced rubber material

Abstract

This invention discloses a method for preparing modified aramid pulp-reinforced rubber materials, belonging to the field of rubber reinforcement materials technology. The method first involves synergistic enzymatic activation using diammonium hydrogen phosphate and cellulase to form micron-sized pores on the surface of the aramid pulp. Subsequently, nano-TiO2 is embedded into the fiber surface layer with the assistance of an ionic liquid to construct a mechanically interlocked structure. Finally, the fiber surface is treated by the self-polymerization reaction of a silane coupling agent and dopamine in Tris buffer, followed by premixing with hydrogenated nitrile butadiene rubber and refining on a two-roll mill to obtain the modified aramid pulp-reinforced rubber material. Through a biomimetic multi-level modification process (multi-level treatment of anchoring layer, embedding layer, and bonding layer to construct a "plant root-soil" biomimetic structure), the surface structure of the aramid pulp is gradually improved, effectively solving the problem of insufficient mechanical property improvement in aramid pulp-reinforced hydrogenated nitrile butadiene rubber in existing technologies, and significantly improving the comprehensive performance of the rubber material.

Description

Technical Field

[0001] This invention belongs to the field of rubber reinforcement material technology, specifically relating to a method for preparing a modified aramid pulp reinforced rubber material. Background Technology

[0002] In modern industry, rubber materials are widely used in numerous sectors such as automotive manufacturing, aerospace, and mechanical engineering due to their excellent elasticity, wear resistance, and corrosion resistance. Hydrogenated nitrile butadiene rubber (NBR), as an important rubber variety, occupies a significant position in friction materials such as seals, piston rings, and water-lubricated bearings due to its outstanding oil resistance and ease of modification. However, its relatively low wear resistance is a key factor limiting its further widespread application. To improve the mechanical and frictional properties of NBR, the use of inorganic fillers, organic fillers, and fiber-reinforced rubber modifications has become an important research direction in the industry.

[0003] Aramid pulp, as a differentiated product of aramid fibers, not only inherits the excellent heat resistance, abrasion resistance, and dimensional stability of aramid fibers, but also possesses a unique surface structure. Its surface is characterized by clusters of fluffy microfibers, with the axial ends of the fibers fibrillating into needle-like tips. This results in a large specific surface area for aramid pulp, providing a wide potential contact area with the reinforcing matrix, theoretically making it an ideal rubber reinforcement material. However, in practical applications, the presence of polar groups such as amino and amide groups on the surface of aramid pulp, while hydrogenated nitrile butadiene rubber (HNBR) is a non-polar or weakly polar material, leads to poor interfacial strength and compatibility between the two. Furthermore, the interaction of surface polar groups within the aramid pulp easily causes entanglement and flocculation, forming a coiled structure that severely affects its dispersibility in HNBR. This uneven dispersion prevents the aramid pulp from fully exerting its reinforcing effect, limiting the improvement of the mechanical properties of HNBR and thus restricting its application expansion in high-end fields.

[0004] Chinese patent document CN117051591A discloses a method and application for modifying aramid pulp. This method uses dopamine and a silane coupling agent to surface-modify short aramid pulp fibers in water. Although this invention improves the interfacial strength between aramid pulp and rubber through chemical modification, it fails to effectively solve the problem of fiber agglomeration in the rubber matrix, resulting in limited improvement in dispersibility and insufficient enhancement of mechanical properties.

[0005] Chinese patent document CN110885461A discloses a method for modifying aramid pulp. This method uses a modifier (polyisocyanate), a coupling agent, and a separating agent (calcium carbonate, talc, carbon black, or silica) to modify the aramid pulp. While this method can improve the dispersibility of aramid pulp in rubber, the separating agent (calcium carbonate, talc, carbon black, or silica) has poor binding ability with the aramid pulp, resulting in limited improvement. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a method for preparing modified aramid pulp-reinforced rubber materials. This invention significantly improves the interfacial bonding and dispersibility between aramid pulp and rubber through a biomimetic multi-level synergistic modification process (diamine hydrogen phosphate / cellulase etching, ionic liquid-assisted nano-TiO2 embedding, and silane / polydopamine modification), resulting in a substantial increase in the tensile strength and tensile stress of the material.

[0007] The specific technical solution of this invention is as follows:

[0008] (1) Immerse aramid pulp in a mixture containing diammonium hydrogen phosphate and cellulase, heat and dry to obtain enzymatically activated modified aramid pulp;

[0009] (2) The enzymatically activated modified aramid pulp was immersed in a mixture containing ionic liquid and nano TiO2 sol, ultrasonicated, and then heat-treated to solidify and dry to obtain nano-composite modified aramid pulp.

[0010] (3) The nanocomposite modified aramid pulp was immersed in Tris buffer containing silane coupling agent and dopamine hydrochloride to undergo self-polymerization reaction, and then dried to obtain biomimetic multi-level modified aramid pulp.

[0011] (4) The biomimetic multi-stage modified aramid pulp is premixed with hydrogenated nitrile rubber and then processed by an open mill to obtain modified aramid pulp reinforced rubber material.

[0012] Preferably, in step (1), the mass concentration of diammonium hydrogen phosphate is 5-10 wt%; the mass concentration of cellulase is 0.5-2 wt%; the mass ratio of aramid pulp to mixed liquor is 0.15-0.2:1; the heat treatment temperature is 40-60℃ and the time is 30-60 min.

[0013] Preferably, in step (2), the ionic liquid is one of 1-propenyl-3-vinylimidazolium chloride, 1-propenyl-3-thiomethylimidazolium chloride, or 1-carboxymethyl-3-methylimidazolium chloride; the mass concentration of the ionic liquid is 8-12 wt%; the mass concentration of the nano-TiO2 sol is 1-3 wt%; the mass ratio of the enzymatically activated modified aramid pulp to the mixture containing the ionic liquid and the nano-TiO2 sol is 0.15-0.2:1; the ultrasonic treatment time is 20-40 min; and the heat treatment curing reaction temperature is 80-100℃ for 1-3 h.

[0014] Preferably, in step (3), the silane coupling agent is one of KH-560, KH-570 or A-151; the mass concentration of the silane coupling agent is 2-5 wt%; the mass concentration of dopamine hydrochloride is 0.5-2 wt%; the mass ratio of the nanocomposite modified aramid pulp to the Tris buffer containing the silane coupling agent and dopamine hydrochloride is 0.15-0.2:1; the self-polymerization reaction temperature is 25-30℃, and the reaction time is 10-15 h.

[0015] Preferably, in step (4), the mass ratio of biomimetic multi-level modified aramid pulp to hydrogenated nitrile rubber is 0.05-0.1:1.

[0016] The beneficial effects of this invention are:

[0017] 1. The technical solution provided by this invention constructs a "plant root-soil" biomimetic structure through a biomimetic multi-level synergistic modification process (anchoring layer, embedding layer, and bonding layer). The anchoring layer is formed by enzymatic activation modification: a low-concentration diammonium hydrogen phosphate solution is used in synergistic treatment with cellulase to etch the surface of aramid pulp under mild conditions, forming micron-level pores, i.e., an anchoring layer mimicking the branching structure of a "root system," while simultaneously enzymatically removing weakly crystalline areas from the surface. The embedding layer is formed by nanocomposite modification: ionic liquid-assisted in-situ deposition of nano-titanium dioxide is used, utilizing the selective dissolution of amorphous regions of the aramid pulp by the ionic liquid to embed TiO2 nanoparticles into the fiber surface, forming a "root-soil" mechanical interlock. The bonding layer is formed by silane coupling agent-dopamine modification: a chemical bridging network is constructed on the surface of nano-TiO2 using silane coupling agent and polydopamine co-modification, enhancing covalent bonding and hydrogen bonding with the rubber matrix. This invention progressively improves the surface structure of aramid pulp. Low-concentration diammonium hydrogen phosphate and cellulase etching form micron-sized pores. Ionic liquid-assisted embedding of nano-titanium dioxide constructs mechanical interlocking, and a silane-polydopamine composite layer forms a chemical bridging network. This biomimetic multi-level modification effectively reduces the polarity difference between aramid pulp and hydrogenated nitrile butadiene rubber, significantly inhibits fiber aggregation, and promotes uniform dispersion of fibers in the rubber matrix. This effectively solves the problem of insufficient mechanical property improvement in aramid pulp-reinforced hydrogenated nitrile butadiene rubber in existing technologies, significantly improving the overall performance of rubber materials.

[0018] 2. The technical solution provided by this invention forms a strong interfacial bond of "mechanical interlocking + chemical bonding" between biomimetic multi-level modified aramid pulp and a rubber matrix, effectively promoting stress transfer. The modified aramid pulp-reinforced rubber material prepared by the method of this invention has a tensile strength of 27.3-27.8 MPa, an elongation at break of 624-629%, a tensile stress (100%) of 4.7-4.9 MPa, a tensile stress (200%) of 8.8-8.9 MPa, and a tear strength of 76-77 N·mm. -1 The hardness is 70. Compared with the unmodified or partially modified control, the prepared rubber material has significantly improved key mechanical properties such as tensile strength, tensile stress, and tear strength, meeting the industrial demand for high-strength and high-toughness rubber materials.

[0019] 3. The technical solution provided by this invention is based on the biomimetic concept of "plant root-soil" and constructs a multi-level interface structure through a multi-dimensional modification strategy, breaking through the limitations of traditional modification. This method not only solves the problem of poor compatibility between aramid pulp and rubber matrix, but also provides a brand-new approach to the design of rubber reinforcing materials through biomimetic principles. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to specific embodiments and comparative examples. The following embodiments and comparative examples are only used to illustrate the technical solutions of the present invention more clearly, and should not be used to limit the scope of protection of the present invention. Example 1

[0021] (1) Weigh 18g of aramid pulp, soak it in 100g of a mixture containing 7wt% diammonium hydrogen phosphate and 1.5wt% cellulase, treat it in a constant temperature water bath at 50℃ for 45min, and dry it to obtain enzymatically activated modified aramid pulp.

[0022] (2) Weigh 18g of enzymatically activated modified aramid pulp, immerse it in 100g of a mixture containing 10wt% 1-propenyl-3-vinylimidazolium chloride and 2wt% nano-TiO2 sol, sonicate for 30min, transfer the mixture to a drying oven, heat treat and solidify at 90℃ for 2h, and dry to obtain nano-composite modified aramid pulp;

[0023] (3) Weigh 18g of nanocomposite modified aramid pulp and immerse it in 100g of Tris buffer containing 3wt% KH-570 and 1.5wt% dopamine hydrochloride to carry out self-polymerization reaction. The self-polymerization reaction temperature is 27℃ and the reaction time is 12h. After drying, biomimetic multi-level modified aramid pulp is obtained.

[0024] (4) 8g of biomimetic multi-stage modified aramid pulp and 100g of hydrogenated nitrile rubber were premixed in an internal mixer. The premixed material was then transferred to a two-roll mill. The roller temperature of the two-roll mill was controlled at 50℃ and the roller gap was adjusted to 4mm for refining. During the refining process, the rubber was cut left and right 4 times to ensure that the material was fully mixed. Then the roller gap was reduced to 1mm and the rubber was wrapped in a triangular shape 5 times. Finally, the roller gap was adjusted to 6mm, the rubber was sheeted, and the rubber was left to stand to obtain the modified aramid pulp reinforced rubber material. Example 2

[0025] (1) Weigh 15g of aramid pulp, soak it in 100g of a mixture containing 5wt% diammonium hydrogen phosphate and 0.5wt% cellulase, treat it in a constant temperature water bath at 40℃ for 30min, and dry it to obtain enzymatically activated modified aramid pulp.

[0026] (2) Weigh 15g of enzymatically activated modified aramid pulp, immerse it in 100g of a mixture containing 8wt% 1-propenyl-3-thiomethylimidazolium chloride and 1wt% nano TiO2 sol, sonicate for 20min, transfer the mixture to a drying oven, heat treat and solidify at 80℃ for 1h, and dry to obtain nano-composite modified aramid pulp;

[0027] (3) Weigh 15g of nanocomposite modified aramid pulp and immerse it in 100g of Tris buffer containing 2wt% KH-560 and 0.5wt% dopamine hydrochloride to carry out self-polymerization reaction. The self-polymerization reaction temperature is 25℃ and the reaction time is 10h. After drying, biomimetic multi-level modified aramid pulp is obtained.

[0028] (4) 5g of biomimetic multi-stage modified aramid pulp and 100g of hydrogenated nitrile rubber were premixed in an internal mixer. The premixed material was then transferred to a two-roll mill. The roller temperature of the two-roll mill was controlled at 50℃ and the roller gap was adjusted to 4mm for refining. During the refining process, the rubber was cut left and right 4 times to ensure that the material was fully mixed. Then the roller gap was reduced to 1mm and the rubber was wrapped in a triangular shape 5 times. Finally, the roller gap was adjusted to 6mm, the rubber was sheeted, and the rubber was left to stand to obtain the modified aramid pulp reinforced rubber material. Example 3

[0029] (1) Weigh 20g of aramid pulp, soak it in 100g of a mixture containing 10wt% diammonium hydrogen phosphate and 2wt% cellulase, treat it in a constant temperature water bath at 60℃ for 60min, and dry it to obtain enzymatically activated modified aramid pulp.

[0030] (2) Weigh 20g of enzymatically activated modified aramid pulp, immerse it in 100g of a mixture containing 12wt% 1-carboxymethyl-3-methylimidazolium chloride and 3wt% nano TiO2 sol, sonicate for 40min, transfer the mixture to a drying oven, heat treat and solidify at 100℃ for 3h, and dry to obtain nanocomposite modified aramid pulp;

[0031] (3) Weigh 20g of nanocomposite modified aramid pulp and immerse it in 100g of Tris buffer containing 5wt% A-151 and 2wt% dopamine hydrochloride to carry out self-polymerization reaction. The self-polymerization reaction temperature is 30℃ and the reaction time is 15h. After drying, biomimetic multi-level modified aramid pulp is obtained.

[0032] (4) 10g of biomimetic multi-stage modified aramid pulp and 100g of hydrogenated nitrile rubber were premixed in an internal mixer. The premixed material was then transferred to a two-roll mill. The roller temperature of the two-roll mill was controlled at 50℃ and the roller gap was adjusted to 4mm for refining. During the refining process, the rubber was cut left and right 4 times to ensure that the material was fully mixed. Then the roller gap was reduced to 1mm and the rubber was wrapped in a triangular shape 5 times. Finally, the roller gap was adjusted to 6mm, the rubber was sheeted, and the rubber was left to stand to obtain the modified aramid pulp reinforced rubber material. Comparative Example 1

[0033] (1) Weigh 18g of aramid pulp, soak it in 100g of a mixture containing 7wt% diammonium hydrogen phosphate and 1.5wt% cellulase, treat it in a constant temperature water bath at 50℃ for 45min, and dry it to obtain enzymatically activated modified aramid pulp.

[0034] (2) 8g of enzymatically activated modified aramid pulp and 100g of hydrogenated nitrile rubber were premixed in an internal mixer. The premixed material was then transferred to a two-roll mill. The roller temperature of the two-roll mill was controlled at 50℃ and the roller gap was adjusted to 4mm for refining. During the refining process, the rubber was cut left and right 4 times to ensure that the material was fully mixed. Then the roller gap was reduced to 1mm and the rubber was wrapped in a triangular shape 5 times. Finally, the roller gap was adjusted to 6mm, the rubber was sheeted, and the rubber was left to stand to obtain the modified aramid pulp reinforced rubber material. Comparative Example 2

[0035] (1) Weigh 18g of aramid pulp, soak it in 100g of a mixture containing 7wt% diammonium hydrogen phosphate and 1.5wt% cellulase, treat it in a constant temperature water bath at 50℃ for 45min, and dry it to obtain enzymatically activated modified aramid pulp.

[0036] (2) Weigh 18g of enzymatically activated modified aramid pulp, immerse it in 100g of a mixture containing 10wt% 1-propenyl-3-vinylimidazolium chloride and 2wt% nano-TiO2 sol, sonicate for 30min, transfer the mixture to a drying oven, heat treat and solidify at 90℃ for 2h, and dry to obtain nano-composite modified aramid pulp;

[0037] (3) 8g of nano-composite modified aramid pulp and 100g of hydrogenated nitrile rubber were premixed in an internal mixer. The premixed material was then transferred to a two-roll mill. The roller temperature of the two-roll mill was controlled at 50℃ and the roller gap was adjusted to 4mm for refining. During the refining process, the rubber was cut left and right 4 times to ensure that the material was fully mixed. Then the roller gap was reduced to 1mm and the rubber was wrapped in a triangular shape 5 times. Finally, the roller gap was adjusted to 6mm, the rubber was sheeted, and the rubber was left to stand to obtain the modified aramid pulp reinforced rubber material. Comparative Example 3

[0038] (1) Weigh 18g of aramid pulp and immerse it in 100g of a mixture containing 10wt% 1-propenyl-3-vinylimidazolium chloride and 2wt% nano-TiO2 sol. After ultrasonic treatment for 30min, transfer the mixture to a drying oven and heat-treat it at 90℃ for 2h. After drying, a modified aramid pulp is obtained.

[0039] (2) Weigh 18g of primary modified aramid pulp and immerse it in 100g of Tris buffer containing 3wt% KH-570 and 1.5wt% dopamine hydrochloride to undergo self-polymerization reaction. The self-polymerization reaction temperature is 27℃ and the reaction time is 12h. After drying, secondary modified aramid pulp is obtained.

[0040] (3) 8g of secondary modified aramid pulp and 100g of hydrogenated nitrile rubber were premixed in an internal mixer. The premixed material was then transferred to a two-roll mill. The roller temperature of the two-roll mill was controlled at 50℃ and the roller gap was adjusted to 4mm for refining. During the refining process, the rubber was cut left and right 4 times to ensure that the material was fully mixed. Then the roller gap was reduced to 1mm and the rubber was wrapped in a triangular shape 5 times. Finally, the roller gap was adjusted to 6mm, the rubber was sheeted, and the rubber was left to stand to obtain the modified aramid pulp reinforced rubber material. Comparative Example 4

[0041] (1) Weigh 18g of aramid pulp, immerse it in 100g of a mixture containing 2wt% nano TiO2 sol, sonicate for 30min, transfer the mixture to a drying oven, heat treat and solidify at 90℃ for 2h, and dry to obtain a modified aramid pulp.

[0042] (2) Weigh 18g of primary modified aramid pulp and immerse it in 100g of Tris buffer containing 3wt% KH-570 and 1.5wt% dopamine hydrochloride to undergo self-polymerization reaction. The self-polymerization reaction temperature is 27℃ and the reaction time is 12h. After drying, secondary modified aramid pulp is obtained.

[0043] (3) 8g of secondary modified aramid pulp and 100g of hydrogenated nitrile rubber were premixed in an internal mixer. The premixed material was then transferred to a two-roll mill. The roller temperature of the two-roll mill was controlled at 50℃ and the roller gap was adjusted to 4mm for refining. During the refining process, the rubber was cut left and right 4 times to ensure that the material was fully mixed. Then the roller gap was reduced to 1mm and the rubber was wrapped in a triangular shape 5 times. Finally, the roller gap was adjusted to 6mm, the rubber was sheeted, and the rubber was left to stand to obtain the modified aramid pulp reinforced rubber material. Comparative Example 5

[0044] (1) Weigh 18g of aramid pulp, soak it in 100g of a mixture containing 7wt% diammonium hydrogen phosphate and 1.5wt% cellulase, treat it in a constant temperature water bath at 50℃ for 45min, and dry it to obtain enzymatically activated modified aramid pulp.

[0045] (2) Weigh 18g of enzymatically activated modified aramid pulp, immerse it in 100g of a mixture containing 2wt% nano TiO2 sol, sonicate for 30min, transfer the mixture to a drying oven, heat treat and solidify at 90℃ for 2h, and dry to obtain secondary modified aramid pulp;

[0046] (3) Weigh 18g of secondary modified aramid pulp and immerse it in 100g of Tris buffer containing 3wt% KH-570 and 1.5wt% dopamine hydrochloride to undergo self-polymerization reaction. The self-polymerization reaction temperature is 27℃ and the reaction time is 12h. After drying, tertiary modified aramid pulp is obtained.

[0047] (4) 8g of tertiary modified aramid pulp and 100g of hydrogenated nitrile rubber were premixed in an internal mixer. The premixed material was then transferred to a two-roll mill. The roller temperature of the two-roll mill was controlled at 50℃ and the roller gap was adjusted to 4mm for refining. During the refining process, the rubber was cut left and right 4 times to ensure that the material was fully mixed. Then the roller gap was reduced to 1mm and the rubber was wrapped in a triangular shape 5 times. Finally, the roller gap was adjusted to 6mm, the rubber was sheeted, and the rubber was left to stand to obtain the modified aramid pulp reinforced rubber material. Comparative Example 6

[0048] (1) Weigh 18g of aramid pulp and immerse it in 100g of Tris buffer containing 3wt% KH-570 and 1.5wt% dopamine hydrochloride to carry out self-polymerization reaction. The self-polymerization reaction temperature is 27℃ and the reaction time is 12h. After drying, a modified aramid pulp is obtained.

[0049] (2) 8g of primary modified aramid pulp and 100g of hydrogenated nitrile rubber were premixed in an internal mixer. The premixed material was then transferred to a two-roll mill. The roller temperature of the two-roll mill was controlled at 50℃ and the roller gap was adjusted to 4mm for refining. During the refining process, the rubber was cut left and right 4 times to ensure that the material was fully mixed. Then the roller gap was reduced to 1mm and the rubber was wrapped in a triangular shape 5 times. Finally, the roller gap was adjusted to 6mm, the rubber was sheeted, and the rubber was left to stand to obtain the modified aramid pulp reinforced rubber material. Comparative Example 7

[0050] (1) Weigh 18g of aramid pulp and immerse it in 100g of Tris buffer containing 3wt% KH-570 and 1.5wt% dopamine hydrochloride to carry out self-polymerization reaction. The self-polymerization reaction temperature is 27℃ and the reaction time is 12h. After drying, a modified aramid pulp is obtained.

[0051] (2) Weigh 18g of primary modified aramid pulp, immerse it in 100g of a mixture containing 10wt% 1-propenyl-3-vinylimidazolium chloride and 2wt% nano TiO2 sol, sonicate for 30min, transfer the mixture to a drying oven, heat treat and cure at 90℃ for 2h, and dry to obtain secondary modified aramid pulp;

[0052] (3) Weigh 18g of secondary modified aramid pulp, soak it in 100g of a mixture containing 7wt% diammonium hydrogen phosphate and 1.5wt% cellulase, treat it in a constant temperature water bath at 50℃ for 45min, and dry it to obtain tertiary modified aramid pulp.

[0053] (4) 8g of tertiary modified aramid pulp and 100g of hydrogenated nitrile rubber were premixed in an internal mixer. The premixed material was then transferred to a two-roll mill. The roller temperature of the two-roll mill was controlled at 50℃ and the roller gap was adjusted to 4mm for refining. During the refining process, the rubber was cut left and right 4 times to ensure that the material was fully mixed. Then the roller gap was reduced to 1mm and the rubber was wrapped in a triangular shape 5 times. Finally, the roller gap was adjusted to 6mm, the rubber was sheeted, and the rubber was left to stand to obtain the modified aramid pulp reinforced rubber material. Comparative Example 8

[0054] 8g of aramid pulp and 100g of hydrogenated nitrile butadiene rubber were premixed in an internal mixer. The premixed material was then transferred to a two-roll mill, with the roll temperature controlled at 50℃ and the roll gap adjusted to 4mm for refining. During the refining process, the rubber was first cut left and right four times to ensure thorough mixing. Then, the roll gap was reduced to 1mm, and the mixture was formed into triangular bundles five times. Finally, the roll gap was adjusted to 6mm, the rubber was sheeted, and the sheet was left to stand to obtain the aramid pulp-reinforced rubber material.

[0055] Blank example

[0056] 100g of hydrogenated nitrile butadiene rubber was subjected to open mill refining. The roller temperature of the open mill was controlled at 50℃, and the roller gap was adjusted to 4mm. During the refining process, the rubber was first cut left and right 4 times; then the roller gap was reduced to 1mm, and triangular wrapping was performed 5 times; finally, the roller gap was adjusted to 6mm, the sheet was cut, and the rubber material was obtained.

[0057] The tensile strength, stress at a given elongation, and elongation at break of rubber are tested according to standard GB / T528-2009; the tear strength of rubber is tested according to standard GB / T529-2008; and the Shore A hardness of rubber is tested according to standard GB / T531.1-2008.

[0058] The relevant test data for Examples 1-3, Comparative Examples 1-8, and the blank example are shown in Table 1:

[0059]

[0060] From the table above, we can see that:

[0061] In Examples 1-3 (complete synergistic modification), the tensile strength was 27.3-27.8 MPa, the elongation at break was 624-629%, the stress at a given elongation (100%) was 4.7-4.9 MPa, the stress at a given elongation (200%) was 8.8-8.9 MPa, and the tear strength was 76-77 N·mm. -1 With a hardness of 70, the performance data of all embodiments significantly outperformed all comparative examples and blank examples.

[0062] As shown in Example 1 and Comparative Example 1, surface enzymatic activation modification of aramid pulp, while slightly improving compatibility, has extremely limited effect. Enzymatic activation modification only provides a foundation for subsequent treatments and cannot significantly improve rubber performance itself. As shown in Example 1 and Comparative Example 2, surface enzymatic activation modification and nanocomposite modification of aramid pulp successfully constructed a "mechanically interlocked" structure, but lacked "chemical bonding." The interfacial bonding strength still has significant room for improvement. The large difference in tensile stress and tensile strength indicates that chemical bonding is crucial for improving material rigidity and load-bearing capacity; it can transform mechanical bonding into a stronger mechanical-chemical synergistic bond. As shown in Example 1 and Comparative Examples 3-5, the tensile stress (100%) in Example 1 is significantly higher than that in Comparative Example 3, by approximately 63%, indicating that enzymatic activation modification is the foundation for the success of all subsequent modification processes. Without the micron-level rough surface and pores formed by enzymatic activation modification, the modification effect is greatly reduced. In Comparative Example 4, ionic liquid was omitted, and only TiO2 sol was used for treatment. The performance of Example 5 was slightly lower than that of Comparative Example 3, and the performance of Comparative Example 5 was lower than that of Example 1. This indicates that the ionic liquid played an "optimization" and "strengthening" role in the modification. Its function is to swell the amorphous region of the aramid pulp, creating more space and binding sites for the embedding of nano-TiO2, making the embedding effect more solid. Although omitting the ionic liquid still has some effect, it cannot achieve the optimal performance. As can be seen from Example 1 and Comparative Example 6, although simple surface chemical modification can improve some compatibility, the effect is far less than that of complete synergistic modification. Without etching and nanoparticle embedding to increase the specific surface area and mechanical anchoring points, the grafting efficiency and bonding strength of chemical modification are limited. As can be seen from Example 1 and Comparative Example 7, the modification order of Comparative Example 7 is reversed, and its performance is only comparable to that of Comparative Example 6 which only has chemical modification. Chemical bridging first will coat the fiber and block the channels for subsequent processing, and etching last will destroy the already constructed interface structure. Only by following the biomimetic logic of "from the surface to the core, layer by layer" can a multi-level reinforcement structure be successfully constructed. Comparative Example 8 shows that its various properties are almost identical to the blank example, and some indicators are even slightly worse. This indicates that unmodified aramid pulp, due to its strong polarity and easy agglomeration, has extremely poor compatibility with rubber. Not only can it not play a reinforcing role, but it may also cause stress defects due to agglomeration points, leading to a decline in performance.

[0063] In summary, the above comparisons use Example 1 as a benchmark against other comparative examples and existing technologies. Other examples also exhibit similar data and comparative performance to Comparative Example 1. Each step in the biomimetic multi-level modification process is necessary and indispensable. Enzymatic activation modification lays the foundation for nanocomposite modification, while nanocomposite modification provides a platform for chemical modification. Following the biomimetic logic of "from the surface to the core, layer by layer," the multiple synergistic effects of "mechanical interlocking + chemical bonding" can be achieved. The omission of any step will lead to a decline in final performance. The biomimetic multi-level modification technology described in this invention solves the problem of poor compatibility between aramid pulp and the rubber matrix through a synergistic interface enhancement mechanism, significantly improving the mechanical properties of hydrogenated nitrile butadiene rubber and providing new ideas for the design of high-performance rubber composite materials.

[0064] Finally, it should be noted that the specific embodiments described herein are merely illustrative of the spirit of the invention and are not intended to limit the implementation of the invention. Those skilled in the art can make other modifications or additions to the described embodiments and use similar methods to substitute them; it is neither necessary nor possible to exemplify all embodiments here. However, obvious variations or modifications arising from the essential spirit of the invention still fall within the protection scope of the invention.

Claims

1. A method for preparing a modified aramid pulp-reinforced rubber material, characterized in that, Includes the following steps: (1) The aramid pulp was immersed in a mixture containing diammonium hydrogen phosphate and cellulase, heated and dried to obtain enzymatically activated modified aramid pulp; micron-sized pores were formed on the surface of the aramid pulp; (2) The enzymatically activated modified aramid pulp was immersed in a mixture containing ionic liquid and nano TiO2 sol, ultrasonicated and then heat-treated to solidify and dry to obtain nano-composite modified aramid pulp; the selective dissolution of the amorphous region of the aramid pulp by the ionic liquid allowed TiO2 nanoparticles to embed into the fiber surface, forming a "root-soil" mechanical interlock. (3) The nanocomposite modified aramid pulp was immersed in Tris buffer containing silane coupling agent and dopamine hydrochloride to undergo self-polymerization reaction, and then dried to obtain biomimetic multi-level modified aramid pulp. A chemical bridging network was constructed on the surface of nano-TiO2 by co-modification with silane coupling agent and polydopamine; (4) The biomimetic multi-stage modified aramid pulp is premixed with hydrogenated nitrile rubber and then processed by an open mill to obtain modified aramid pulp reinforced rubber material. In step (1), the mass concentration of diammonium hydrogen phosphate is 5-10 wt%; the mass concentration of cellulase is 0.5-2 wt%; and the mass ratio of aramid pulp to the mixed liquid is 0.15-0.2:

1.

2. The method for preparing the modified aramid pulp reinforced rubber material according to claim 1, characterized in that, In step (1), the heating temperature is 40-60℃ and the time is 30-60min.

3. The method for preparing the modified aramid pulp reinforced rubber material according to claim 1, characterized in that, In step (2), the ionic liquid is one of 1-propenyl-3-vinylimidazolium chloride, 1-propenyl-3-thiomethylimidazolium chloride, or 1-carboxymethyl-3-methylimidazolium chloride; the mass concentration of the ionic liquid is 8-12 wt%; the mass concentration of the nano-TiO2 sol is 1-3 wt%; and the mass ratio of the enzymatically hydrolyzed and activated modified aramid pulp to the mixture containing the ionic liquid and the nano-TiO2 sol is 0.15-0.2:

1.

4. The method for preparing the modified aramid pulp reinforced rubber material according to claim 1, characterized in that, In step (2), the ultrasonic treatment time is 20-40 min; the heat treatment curing reaction temperature is 80-100℃ and the time is 1-3 h.

5. The method for preparing the modified aramid pulp reinforced rubber material according to claim 1, characterized in that, In step (3), the silane coupling agent is one of KH-560, KH-570, or A-151; the mass concentration of the silane coupling agent is 2-5 wt%; and the mass concentration of dopamine hydrochloride is 0.5-2 wt%. The mass ratio of nanocomposite modified aramid pulp to Tris buffer containing silane coupling agent and dopamine hydrochloride is 0.15-0.2:

1.

6. The method for preparing the modified aramid pulp reinforced rubber material according to claim 1, characterized in that, In step (3), the self-polymerization reaction temperature is 25-30℃ and the reaction time is 10-15h.

7. The method for preparing the modified aramid pulp reinforced rubber material according to claim 1, characterized in that, In step (4), the mass ratio of biomimetic multi-level modified aramid pulp to hydrogenated nitrile rubber is 0.05-0.1:1.

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