Application of supramolecular polymer in modification of carboxyl nitrile rubber, modified carboxyl nitrile rubber and preparation method thereof

Abstract

The application discloses application of a supramolecular polymer in modification of carboxyl nitrile rubber, modified carboxyl nitrile rubber and a preparation method thereof, and belongs to the technical field of reinforced and toughened carboxyl nitrile rubber. The technical scheme comprises that the supramolecular polymer is a supramolecular polymer formed based on hydrogen bond interaction; and the supramolecular polymer is used as a reinforcing agent and a toughening agent in modification of the carboxyl nitrile rubber to obtain the modified carboxyl nitrile rubber. The application is applied to the aspect of reinforcing and toughening of the carboxyl nitrile rubber, solves the technical problems of difficult filler dispersion and complex interface design when existing fillers are used to reinforce and toughen XNBR, and solves the technical problems of processing difficulty and accelerated aging of rubber caused by introduction of metal cations when metal salts are used to reinforce and toughen XNBR, so that the rubber becomes hard and brittle quickly and loses use value, and the application has the characteristics of being capable of significantly improving the strength and toughness of the XNBR.

Description

Technical Field

[0001] This invention belongs to the field of reinforced and toughened carboxylated nitrile butadiene rubber technology, and particularly relates to the application of a supramolecular polymer in the modification of carboxylated nitrile butadiene rubber, modified carboxylated nitrile butadiene rubber and its preparation method. Background Technology

[0002] Carboxylated acrylonitrile butadiene rubber (XNBR) is a terpolymer of butadiene, acrylonitrile, and organic acid monomers (acrylic acid, methacrylic acid, etc.). The introduction of carboxyl groups increases the polarity of XNBR, enhancing its compatibility with polar materials such as polyvinyl chloride and phenolic resins, and further improving its oil resistance. Simultaneously, the introduction of carboxyl groups also improves the tensile strength of the material, especially at high temperatures. In addition, XNBR exhibits good adhesion and aging resistance, improving its abrasion resistance and tear strength. XNBR can be used alone or in combination with other elastomers to manufacture products such as hoses, tape seals, O-rings, rubber rollers, and rubber shoes. Although the introduction of carboxyl groups improves the basic mechanical properties of XNBR to some extent, further reinforcement and toughening modification is still necessary to achieve optimal application value.

[0003] In the rubber industry, rubber is typically reinforced and toughened by filling it with large amounts of nano-reinforcing fillers (such as carbon black, silica, graphene, and carbon nanotubes). However, the addition of fillers also brings other problems: on the one hand, the prerequisite for filler-reinforced and toughened XNBR is that the filler is well dispersed in the rubber matrix; however, nano-fillers are prone to agglomeration in the rubber matrix, which reduces the reinforcing and toughening effect. On the other hand, the performance of XNBR composites strongly depends on the interfacial strength between the rubber and the filler, which usually requires complex design and optimization of the interface. Finally, when the filler is mixed with rubber, the filler nanoparticles fly around, creating a poor processing environment and harming the health of operators.

[0004] To enhance and toughen XNBR, metal salts can be introduced into the XNBR crosslinking network. The strength and toughness of XNBR can be improved by the in-situ formation of metal coordination bonds between the COOH groups in XNBR and metal ions. However, during rubber compounding, the added metal cations rapidly form ionic bonds with the carboxyl groups in XNBR, making processing difficult. Furthermore, the introduction of metal ions accelerates rubber aging, causing the rubber to harden and become brittle rapidly, ultimately rendering it unusable. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the technical problems to be solved by the present invention are to overcome the difficulties in filler dispersion and complex interface design when reinforcing and toughening XNBR with existing fillers, and the difficulties in processing and accelerated aging of rubber caused by the introduction of metal cations when reinforcing and toughening XNBR with metal salts, which make the rubber harden and become brittle quickly and lose its usability. The present invention proposes the application of a supramolecular polymer that can significantly improve the strength and toughness of XNBR in the modification of carboxylated nitrile butadiene rubber, the modified carboxylated nitrile butadiene rubber and its preparation method.

[0006] To solve the aforementioned technical problem, the technical solution adopted by the present invention is as follows:

[0007] This invention provides an application of a supramolecular polymer in the modification of carboxylated nitrile butadiene rubber, wherein the supramolecular polymer is a supramolecular polymer formed based on hydrogen bonding interactions; the supramolecular polymer is used as a reinforcing agent and toughening agent in the modification of carboxylated nitrile butadiene rubber to obtain modified carboxylated nitrile butadiene rubber.

[0008] Preferably, the amount of the supramolecular polymer used is 4-7 phr.

[0009] Preferably, the supramolecular polymer is prepared by reacting 1,12-diaminododecane with acrylic acid.

[0010] Preferably, the molar ratio of 1,12-diaminododecane to acrylic acid is 1:2-4.

[0011] In another aspect, the present invention provides a modified carboxylated nitrile rubber obtained by applying the supramolecular polymer described in any one of the above-mentioned methods in the modification of carboxylated nitrile rubber.

[0012] Preferably, the modified carboxylated nitrile rubber is obtained by mixing the supramolecular polymer with the carboxylated nitrile rubber and then vulcanizing it.

[0013] The present invention also provides a method for preparing the modified carboxylated nitrile butadiene rubber according to any one of the above claims, comprising a supramolecular polymer synthesis step and a step of modifying the carboxylated nitrile butadiene rubber using the supramolecular polymer.

[0014] Preferably, the supramolecular polymer synthesis step includes: dissolving 1,12-diaminododecane in dichloromethane, adding acrylic acid while stirring under ice bath conditions, stirring until homogeneous, heating to 55°C for reaction, purifying and drying to obtain the supramolecular polymer.

[0015] Preferably, the step of modifying the carboxylated nitrile rubber with the supramolecular polymer includes: adding the supramolecular polymer, the carboxylated nitrile rubber and other rubber vulcanizing aids other than sulfur into a mixer to mix and obtain a compound; mixing the compound with sulfur on a two-roll mill at room temperature; and vulcanizing it through a flat vulcanizing machine to obtain the modified carboxylated nitrile rubber.

[0016] Preferably, the vulcanization temperature for obtaining the modified carboxylated nitrile rubber by vulcanization using a flat vulcanizing machine is 170°C, and the vulcanization pressure is 10 MPa.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] This invention provides an application of supramolecular polymers in the modification of carboxylated nitrile butadiene rubber. The supramolecular polymer is used as a reinforcing and toughening agent to modify carboxylated nitrile butadiene rubber. When the modified carboxylated nitrile butadiene rubber is subjected to tensile stress, the hydrogen bonds of the supramolecular polymer itself and the hydrogen bonds between the supramolecular polymer and the carboxylated nitrile butadiene rubber break preferentially over the covalent bonds to dissipate energy. The breaking of hydrogen bonds will prevent the covalently cross-linked carboxylated nitrile butadiene rubber from being destroyed prematurely due to stress concentration, thereby significantly improving the strength and toughness of the carboxylated nitrile butadiene rubber.

[0019] This invention provides a modified carboxylated butadiene-acrylonitrile rubber, which has high strength and toughness;

[0020] The present invention also provides a method for preparing modified carboxylated nitrile butadiene rubber, which does not change the existing processing method of carboxylated nitrile butadiene rubber or increase its processing difficulty. It has the characteristics of simple preparation method, low cost and easy industrial production. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the network structure of the modified carboxylated butadiene-acrylonitrile rubber provided in an embodiment of the present invention;

[0022] Figure 2 This is a flow chart of the preparation process of modified carboxylated butadiene-acrylonitrile rubber provided in the embodiments of the present invention;

[0023] Figure 3 This is a schematic diagram showing the state of comparative samples 1 and 2 and samples 1-6 provided in the embodiments of the present invention;

[0024] Figure 4 Cyclic tensile curves of comparative sample 1 and samples 1-3 provided in the embodiments of the present invention;

[0025] Figure 5 Cyclic stretching curves of comparative sample 1 and samples 4-6 provided in the embodiments of the present invention. Detailed Implementation

[0026] The technical solutions in specific embodiments of the present invention will now be described in detail and completely with reference to the accompanying drawings. Obviously, the described embodiments are merely some specific implementations of the overall technical solution of the present invention, and not all implementations. Based on the overall concept of the present invention, all other embodiments obtained by those skilled in the art fall within the protection scope of the present invention.

[0027] This invention provides an application of supramolecular polymers in the modification of carboxylated nitrile butadiene rubber (CBR). The supramolecular polymers are formed based on hydrogen bonding interactions. In the modification of CBR, the supramolecular polymers act as reinforcing and toughening agents to modify the CBR, resulting in modified CBR. This technical solution utilizes supramolecular polymers as reinforcing and toughening agents to modify CBR. When the modified CBR is subjected to tensile stress, the hydrogen bonds within the supramolecular polymer itself and the hydrogen bonds between the supramolecular polymer and the CBR preferentially break than covalent bonds to dissipate energy. The breaking of hydrogen bonds prevents the covalently cross-linked CBR from prematurely failing due to stress concentration, thereby significantly improving the strength and toughness of the CBR.

[0028] It should be noted that supramolecular polymers include polymers formed based on various intermolecular interactions and their synergistic or multiple interactions, such as coordination interactions, host-guest interactions, charge transfer interactions, and π-π interactions. This invention specifically defines supramolecular polymers as those formed based on hydrogen bonding interactions. This is because supramolecular polymers formed based on hydrogen bonding interactions are linked by hydrogen bonds between primary and secondary amine groups at the ends of small molecules and carboxyl groups at the ends of small molecules. Furthermore, the primary, secondary, and carboxyl groups in the supramolecular polymer can also form hydrogen bonds with the carboxyl groups in XNBR. Since the bond energy of hydrogen bonds is lower than that of covalent bonds, hydrogen bonds break preferentially over covalent bonds when the material is subjected to tensile stress. The mechanism by which supramolecular polymers reinforce and toughen XNBR involves two aspects: firstly, the energy is dissipated by the breaking of hydrogen bonds within the supramolecular polymer itself; secondly, the energy is dissipated by the breaking of hydrogen bonds between the supramolecular polymer and XNBR. The preferential breaking of hydrogen bonds over covalent bonds prevents the premature destruction of covalently cross-linked XNBR due to stress concentration, thereby significantly improving the strength and toughness of the material. In addition, this invention uses supramolecular polymers as reinforcing and toughening agents to modify carboxylated nitrile rubber. Due to the reversible nature of hydrogen bonds, after the modified carboxylated nitrile rubber is subjected to tensile stress, the broken hydrogen bonds can reconnect and form again, thereby achieving a repeated toughening effect and further ensuring the strength and toughness of the modified carboxylated nitrile rubber.

[0029] Furthermore, the supramolecular polymer is easily dispersed in the XNBR matrix and does not affect the mixing process. This is because both the supramolecular polymer and XNBR are polar and compatible with each other. In addition, the supramolecular polymer defined in this invention is based on hydrogen bonds between monomers. These hydrogen bonds dissociate during the blending of the supramolecular polymer, XNBR, and rubber crosslinking aid. The supramolecular polymer is dispersed in the XNBR matrix in the form of monomer molecules. After the sample is vulcanized, these monomer molecules reassociate with each other through hydrogen bonds, forming a supramolecular polymer in situ in the XNBR matrix. Therefore, there is no problem of supramolecular polymer agglomeration degrading the material performance.

[0030] In a preferred embodiment, the supramolecular polymer is used in an amount of 4-7 phr. This technical solution specifically limits the amount of supramolecular polymer used, which not only achieves the optimal reinforcement and toughening effect on XNBR, but also helps to reduce the impact of the supramolecular polymer on the original XNBR system, ensuring that other properties of XNBR are not affected. It is understood that the amount of supramolecular polymer used can also be 5 phr, 6 phr, or any value within this range. Here, phr represents the percentage content of additives in the rubber. For example, 4 phr represents 4 g of supramolecular polymer added per 100 g of rubber. Of course, g can also be replaced with kg, t, etc.

[0031] In a preferred embodiment, the supramolecular polymer is prepared by reacting 1,12-diaminododecane (DDA) with acrylic acid (AA). Optionally, the molar ratio of 1,12-diaminododecane to acrylic acid is 1:2-4. This embodiment defines the supramolecular polymer as a combination of a series of small molecules with different structures, and the content of carboxyl groups in the synthesized supramolecular polymer material increases with the increase of the amount of AA. The reaction formula of 1,12-diaminododecane (DDA) with acrylic acid (AA) is as follows:

[0032]

[0033] The above embodiments specifically limit the molar ratio of 1,12-diaminododecane to acrylic acid to 1:2-4. This is because experiments have shown that when the monomer ratio is higher than 1:2, the resulting supramolecular polymer blended with XNBR and vulcanized results in uneven surfaces, excessive shrinkage, and substandard sample preparation. Conversely, when the monomer ratio is lower than 1:4, the strength and toughness of the resulting supramolecular polymer blended with XNBR decrease. It is understood that the molar ratio of 1,12-diaminododecane to acrylic acid can also be 1:3 or any value within that range.

[0034] Another aspect of the present invention provides a modified carboxylated nitrile rubber obtained by applying the supramolecular polymer described in any one of the above claims in the modification of carboxylated nitrile rubber, the modified carboxylated nitrile rubber having the following properties: Figure 1 The network structure is shown. In a preferred embodiment, the modified carboxylated nitrile butadiene rubber is obtained by mixing the supramolecular polymer with the carboxylated nitrile butadiene rubber and then vulcanizing it. This modified carboxylated nitrile butadiene rubber retains the original properties of the carboxylated nitrile butadiene rubber while exhibiting high strength and toughness. This modified carboxylated nitrile butadiene rubber strengthens and toughens the XNBR by constructing a supramolecular polymer in situ within a sulfur-vulcanized XNBR matrix. When the material is subjected to stress and deformation, energy is dissipated through the preferential breaking of hydrogen bonds within the supramolecular polymer itself and between the supramolecular polymer and XNBR, preventing premature material failure due to the breakage of covalent bonds in the XNBR main chain. This process reinforces and toughens the XNBR, whereas it is difficult to achieve simultaneous improvement in strength and toughness using filler-reinforced XNBR methods.

[0035] This invention also provides a method for preparing the modified carboxylated butadiene-acrylonitrile rubber according to any one of the above claims, such as... Figure 2 As shown, the process includes a supramolecular polymer synthesis step and a step of modifying the carboxylated nitrile rubber using the supramolecular polymer. In this embodiment, the supramolecular polymer is easily dispersed in the XNBR matrix and does not affect the mixing process. This is because, on the one hand, both the supramolecular polymer and XNBR are polar and thus compatible; on the other hand, the polar supramolecular polymer is formed based on hydrogen bonds between monomers. These hydrogen bonds dissociate during the blending of the supramolecular polymer, XNBR, and rubber additives, dispersing as monomer molecules in the polar XNBR matrix. After vulcanization, these monomer molecules reassociate through hydrogen bonds, forming a supramolecular polymer in situ within the XNBR matrix, thus ensuring the dispersibility of the supramolecular polymer in the XNBR matrix.

[0036] In a preferred embodiment, the supramolecular polymer synthesis step includes: dissolving 1,12-diaminododecane in dichloromethane, adding acrylic acid while stirring under ice bath conditions, stirring until homogeneous, heating to 55°C for reaction, purifying and drying to obtain the supramolecular polymer. This supramolecular polymer synthesis method is simple, with a yield exceeding 90%, and the solvent used in the synthesis process is non-toxic and recyclable. Specifically, the synthesis method includes: dissolving DDA in dichloromethane, adding AA (nDDA:nAA = 1:2-4) dropwise to the above solution while stirring under ice bath conditions, continuing to stir the solution for 0.5 h after the AA addition is complete, raising the solution temperature to 55°C, and reacting at this temperature for 8 h. After the reaction, the product is purified with anhydrous ethanol, and the purified product is vacuum dried at 80°C for 12 h to obtain the supramolecular polymer, wherein the yield of the supramolecular polymer is >90%.

[0037] In a preferred embodiment, the step of modifying the carboxylated nitrile butadiene rubber (XNBR) using the supramolecular polymer includes: mixing the supramolecular polymer, the carboxylated nitrile butadiene rubber, and other rubber vulcanizing auxiliaries (excluding sulfur) in a mixer to obtain a compound; mixing the compound with sulfur on a two-roll mill at room temperature; and vulcanizing the compound using a flat vulcanizing machine to obtain the modified carboxylated nitrile butadiene rubber. In this process, the polar supramolecular polymer is formed based on hydrogen bonds between monomers. These hydrogen bonds dissociate during the blending of the supramolecular polymer, XNBR, and rubber auxiliaries, allowing the supramolecular polymer to disperse as monomer molecules within the XNBR matrix. After vulcanization, these monomer molecules reassociate through hydrogen bonds, forming a supramolecular polymer in situ within the XNBR matrix, ensuring the dispersion of the supramolecular polymer within the XNBR matrix. This preparation process is simple and easy to operate. Adding a supramolecular polymer to reinforce and toughen XNBR does not change the XNBR processing method or increase its processing difficulty. The processing equipment is general-purpose rubber processing equipment, enabling large-scale industrial production and facilitating market promotion. In a preferred embodiment, the vulcanization temperature for obtaining the modified carboxylated nitrile rubber by vulcanization using a flat vulcanizing machine is 170°C, and the vulcanization pressure is 10 MPa.

[0038] To more clearly and in detail introduce the application of the supramolecular polymer provided in the embodiments of the present invention in the modification of carboxylated nitrile butadiene rubber, the modified carboxylated nitrile butadiene rubber and its preparation method, the following description will be based on specific embodiments.

[0039] Example 1

[0040] Synthesis of supramolecular polymer (DDA1AA2):

[0041] (1) Dissolve 10g of DDA in 100mL of dichloromethane in a 150mL three-necked flask;

[0042] (2) Under ice bath conditions, 7.2g of AA (nDDA:nAA=1:2) was added dropwise to the above solution while stirring. After the addition of AA was completed, the solution was stirred for another 0.5h.

[0043] (3) Raise the solution temperature to 55℃ and react at this temperature for 8 hours;

[0044] (4) After the reaction was completed, the product was purified by anhydrous ethanol and the purified product was dried under vacuum at 80°C for 12 h to obtain DDA1AA2 (yield > 90%).

[0045] Preparation of carboxylated acrylonitrile butadiene rubber / supramolecular polymer vulcanizate:

[0046] The internal mixer was set to an initial temperature of 60℃ and a rotor speed of 70 rpm. 100 kg of carboxylated nitrile rubber, 5 kg of zinc oxide, 1 kg of stearic acid, 1 kg of accelerator MBTS, and 4 kg of supramolecular polymer DDA1AA2 were added to the internal mixer and mixed for 8 min. At room temperature, 1.5 kg of sulfur was added to the resulting compound on a two-roll mill, and then the mixture was rolled into a thin sheet of about 2 mm after 6 triangular passes. The resulting compound was vulcanized at 170℃ for the correct vulcanization time and at a vulcanization pressure of 10 MPa using a flat vulcanizing machine. Sample 1 was obtained after vulcanization.

[0047] Example 2

[0048] Synthesis of supramolecular polymer (DDA1AA3):

[0049] (1) Dissolve 10g of DDA in 100mL of dichloromethane in a 150mL three-necked flask;

[0050] (2) Under ice bath conditions, 10.8g of AA (nDDA:nAA=1:3) was added dropwise to the above solution while stirring. After the addition of AA was completed, the solution was stirred for another 0.5h.

[0051] (3) Raise the solution temperature to 55℃ and react at this temperature for 8 hours;

[0052] (4) After the reaction was completed, the product was purified by anhydrous ethanol and the purified product was dried under vacuum at 80°C for 12 h to obtain DDA1AA3 (yield > 90%).

[0053] Preparation of carboxylated acrylonitrile butadiene rubber / supramolecular polymer vulcanizate:

[0054] The internal mixer was set to an initial temperature of 60℃ and a rotor speed of 70 rpm. 100 kg of carboxylated nitrile rubber, 5 kg of zinc oxide, 1 kg of stearic acid, 1 kg of accelerator MBTS, and 4 kg of supramolecular polymer DDA1AA3 were added to the internal mixer and mixed for 8 min. At room temperature, 1.5 kg of sulfur was added to the resulting compound on a two-roll mill, and then the mixture was rolled into a thin sheet of about 2 mm after 6 triangular passes. The resulting compound was vulcanized at 170℃ for the correct vulcanization time and at a vulcanization pressure of 10 MPa using a flat vulcanizing machine. Sample 2 was obtained after vulcanization.

[0055] Example 3

[0056] Synthesis of supramolecular polymer (DDA1AA4):

[0057] (1) Dissolve 10g of DDA in 100mL of dichloromethane in a 150mL three-necked flask;

[0058] (2) Under ice bath conditions, 14.4 g of AA (nDDA:nAA = 1:4) was added dropwise to the above solution while stirring. After the addition of AA was completed, the solution was stirred for another 0.5 h.

[0059] (3) Raise the solution temperature to 55℃ and react at this temperature for 8 hours;

[0060] (4) After the reaction was completed, the product was purified by anhydrous ethanol and the purified product was dried under vacuum at 80°C for 12 h to obtain DDA1AA4 (yield > 90%).

[0061] Preparation of carboxylated acrylonitrile butadiene rubber / supramolecular polymer vulcanizate:

[0062] The internal mixer was set to an initial temperature of 60℃ and a rotor speed of 70 rpm. 100 kg of carboxylated nitrile rubber, 5 kg of zinc oxide, 1 kg of stearic acid, 1 kg of accelerator MBTS, and 4 kg of supramolecular polymer DDA1AA4 were added to the internal mixer and mixed for 8 min. At room temperature, 1.5 kg of sulfur was added to the resulting compound on a two-roll mill, and then the mixture was rolled into a thin sheet of about 2 mm after 6 triangular passes. The resulting compound was vulcanized at 170℃ for the correct vulcanization time using a flat vulcanizing machine with a vulcanization pressure of 10 MPa. Sample 3 was obtained after vulcanization.

[0063] Example 4

[0064] The synthesis of the supramolecular polymer (DDA1AA3) was carried out according to Example 2.

[0065] Preparation of carboxylated acrylonitrile butadiene rubber / supramolecular polymer vulcanizate:

[0066] The internal mixer was set to an initial temperature of 60℃ and a rotor speed of 70 rpm. 100 kg of carboxylated nitrile rubber, 5 kg of zinc oxide, 1 kg of stearic acid, 1 kg of accelerator MBTS, and 3 kg of supramolecular polymer DDA1AA4 were added to the internal mixer and mixed for 8 min. At room temperature, 1.5 kg of sulfur was added to the resulting compound on a two-roll mill, and then the mixture was rolled into a thin sheet of about 2 mm after 6 triangular passes. The resulting compound was vulcanized at 170℃ for the correct vulcanization time using a flat vulcanizing machine with a vulcanization pressure of 10 MPa. Sample 4 was obtained after vulcanization.

[0067] Example 5

[0068] The synthesis of the supramolecular polymer (DDA1AA3) was carried out according to Example 2.

[0069] Preparation of carboxylated acrylonitrile butadiene rubber / supramolecular polymer vulcanizate:

[0070] The internal mixer was set to an initial temperature of 60℃ and a rotor speed of 70 rpm. 100 kg of carboxylated nitrile rubber, 5 kg of zinc oxide, 1 kg of stearic acid, 1 kg of accelerator MBTS, and 5 kg of supramolecular polymer DDA1AA4 were added to the internal mixer and mixed for 8 min. At room temperature, 1.5 kg of sulfur was added to the resulting compound on a two-roll mill, and then the mixture was rolled into a thin sheet of about 2 mm after 6 triangular passes. The resulting compound was vulcanized at 170℃ for the correct vulcanization time using a flat vulcanizing machine with a vulcanization pressure of 10 MPa. Sample 5 was obtained after vulcanization.

[0071] Example 6

[0072] The synthesis of the supramolecular polymer (DDA1AA3) was carried out according to Example 2.

[0073] Preparation of carboxylated acrylonitrile butadiene rubber / supramolecular polymer vulcanizate:

[0074] The internal mixer was set to an initial temperature of 60℃ and a rotor speed of 70 rpm. 100 kg of carboxylated nitrile rubber, 5 kg of zinc oxide, 1 kg of stearic acid, 1 kg of accelerator MBTS, and 7 kg of supramolecular polymer DDA1AA4 were added to the internal mixer and mixed for 8 min. At room temperature, 1.5 kg of sulfur was added to the resulting compound on a two-roll mill, and then the mixture was rolled into a thin sheet of about 2 mm after 6 triangular passes. The resulting compound was vulcanized at 170℃ for the correct vulcanization time using a flat vulcanizing machine with a vulcanization pressure of 10 MPa. Sample 6 was obtained after vulcanization.

[0075] Comparative Example 1

[0076] Same as Example 1, except that: the synthesis step of supramolecular polymer (DDA1AA2) is not included, and supramolecular polymer (DDA1AA2) is not added in the preparation process of carboxylated nitrile rubber / supramolecular polymer vulcanizate.

[0077] Comparative Example 2

[0078] Same as Example 1, except that in the synthesis step of supramolecular polymer (DDA1AA2), the molar ratio of DDA to AA is 1:1.

[0079] Comparative Example 3

[0080] Same as Example 1, except that in the synthesis step of supramolecular polymer (DDA1AA2), the molar ratio of DDA to AA is 1:5.

[0081] Comparative Example 4

[0082] Same as Example 4, except that the amount of supramolecular polymer (DDA1AA3) used in the preparation of carboxylated nitrile rubber / supramolecular polymer vulcanizate is 2 phr.

[0083] Comparative Example 5

[0084] Same as Example 4, except that the amount of supramolecular polymer (DDA1AA3) used in the preparation of carboxylated nitrile rubber / supramolecular polymer vulcanizate is 8 phr.

[0085] The ratio of DDA and AA monomers used to synthesize the supramolecular polymers, and the amount of supramolecular polymers used in Examples 1-6 and Comparative Examples 1-5 are shown in Tables 1 and 2.

[0086] Table 1. Monomer ratios and supramolecular polymer amounts used in Examples 1-6

[0087] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 DDA:AA (molar ratio) 1:2 1:3 1:4 1:3 1:3 1:3 Number of servings (phr) 4 4 4 3 5 7

[0088] Table 2 shows the monomer ratios and supramolecular polymer amounts used in comparative examples 1-5.

[0089] Comparison Sample 1 Comparison Sample 2 Comparison Sample 3 Comparison Sample 4 Comparison Sample 5 DDA:AA (molar ratio) - 1:1 1:5 1:3 1:3 Number of servings (phr) 0 4 4 2 8

[0090] from Figure 3 As can be seen, Comparative Sample 1, without any added supramolecular polymer, is smooth and has a certain degree of transparency. Comparative Sample 2, containing a supramolecular polymer synthesized at a monomer ratio of 1:1, is more wrinkled and uneven. Due to the unevenness of Comparative Sample 2, it will not be studied further. Samples 1-6, with the addition of supramolecular polymer, are smooth and highly transparent, indicating that the synthesized supramolecular polymer can be uniformly dispersed in the XNBR matrix using common rubber processing methods without special treatment.

[0091] Tables 3 and 4 show the tensile strength and fracture energy of samples 1-6 and control samples 1-5. Fracture energy is the area under the stress-strain curve; it reflects the toughness of the material, with higher fracture energy indicating greater toughness. The performance of samples 1-3 shows that when the amount of added supramolecular polymer is fixed at 4 phr, the tensile strength and toughness gradually increase with the increase in the proportion of the supramolecular polymer monomer AA, and are both higher than those of XNBR (control sample 1) without supramolecular polymer sulfur treatment. However, when the proportion of the supramolecular polymer monomer AA is further increased, the tensile strength and toughness of XNBR (control sample 3) with this supramolecular polymer are lower than those of sample 3. Therefore, further increasing the proportion of the supramolecular polymer monomer AA is unnecessary. The performance of samples 4-6 shows that when the monomer ratio of the synthesized supramolecular polymer is fixed at 1:3 (i.e., the supramolecular polymer is DDA1AA3), the tensile strength and fracture energy of the XNBR vulcanizate with added supramolecular polymer gradually increase with the gradual increase in the amount of supramolecular polymer, and are also higher than those of control sample 1. When the amount of DDA1AA3 is 2 phr (control sample 4), the tensile strength and fracture energy of the sample are not significantly improved compared with the sample without any supramolecular polymer (control sample 1). This is because hydrogen bonds themselves have low bond energy, and a certain amount needs to be accumulated to significantly improve the strength and toughness of the material. When the amount of DDA1AA3 is 8 phr (control sample 5), the tensile strength and fracture energy of the sample decrease compared with sample 6, proving that the material performance is optimal when the amount of supramolecular polymer is about 7 phr.

[0092] Table 3 Tensile strength and fracture energy of samples 1-6

[0093] Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Tensile strength (MPa) 14.0 20.5 22.3 19.1 21.5 23.7 <![CDATA[Fracture energy (MJ·m -3 )]]> 23.2 30.7 38.5 27.3 35.6 44.7

[0094] Table 4 compares the tensile strength and rupture energy of samples 1-5.

[0095] Comparison Sample 1 Comparison Sample 2 Comparison Sample 3 Comparison Sample 4 Comparison Sample 5 Tensile strength (MPa) 10.8 12.9 17.6 11.1 20.9 <![CDATA[Fracture energy (MJ·m -3 )]]> 14.1 19.6 26.3 15.2 33.2

[0096] Figure 4 , 5 These are the cyclic tensile curves for comparison sample 1 and samples 4-6, from... Figure 4 As can be seen, when the amount of added supramolecular polymer is fixed at 4 phr, the hysteresis loop areas of samples 1-3 are all larger than those of control sample 1. Furthermore, as the proportion of the synthesized supramolecular polymer monomer AA increases, the hysteresis loop area of ​​the samples gradually increases during cyclic tensile testing, indicating a gradual improvement in material toughness. A larger hysteresis loop area indicates more energy dissipated during hydrogen bond fracture under tension, thus improving material toughness. Figure 5As can be seen, when the monomer ratio of the synthesized supramolecular polymer is fixed at 1:3, the hysteresis loop area of ​​samples 4-6 is higher than that of control sample 1. Furthermore, as the amount of supramolecular polymer increases, the hysteresis loop area of ​​the samples gradually increases during cyclic stretching, indicating that the toughness of the material gradually improves.

Claims

1. Use of supramolecular polymers in the modification of carboxylated nitrile rubber, characterized in that, The supramolecular polymer is a supramolecular polymer formed based on hydrogen bond interactions; the supramolecular polymer is used as a reinforcing agent and toughening agent in the modification of carboxylated butadiene-acrylonitrile rubber to obtain modified carboxylated butadiene-acrylonitrile rubber. The amount of the supramolecular polymer used is 4-7 phr; The supramolecular polymer was prepared by reacting 1,12-diaminododecane with acrylic acid; The molar ratio of 1,12-diaminododecane to acrylic acid is 1:2-4.

2. A modified carboxylated nitrile rubber obtained by applying the supramolecular polymer of claim 1 in the modification of carboxylated nitrile rubber.

3. The modified carboxylated nitrile rubber according to claim 2, characterized in that, The modified carboxylated nitrile rubber is obtained by mixing the supramolecular polymer with the carboxylated nitrile rubber and then vulcanizing it.

4. The method of preparing a modified carboxylated nitrile rubber according to claim 2 or 3, characterized in that, It includes a supramolecular polymer synthesis step, and a step of modifying the carboxylated butadiene-acrylonitrile rubber using the supramolecular polymer; The supramolecular polymer synthesis steps include: dissolving 1,12-diaminododecane in dichloromethane, adding acrylic acid while stirring under ice bath conditions, stirring until homogeneous, heating to 55°C for reaction, purifying and drying to obtain the supramolecular polymer; The step of modifying the carboxylated nitrile rubber using the supramolecular polymer includes: adding the supramolecular polymer, the carboxylated nitrile rubber, and other rubber vulcanizing auxiliaries other than sulfur into a mixer to obtain a compound; mixing the compound with sulfur on a two-roll mill at room temperature; and vulcanizing the compound through a flat vulcanizing machine to obtain the modified carboxylated nitrile rubber.

5. The method of preparing a modified carboxylated nitrile rubber according to claim 4, characterized in that, The modified carboxylated nitrile rubber obtained by vulcanization using a flat vulcanizing machine has a vulcanization temperature of 170°C and a vulcanization pressure of 10 MPa.

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