A vulcanized rubber having a sulfur-containing regulator regulating a vulcanization network structure and a method for preparing the same

Abstract

The present application belongs to the technical field of rubber, and particularly relates to vulcanized rubber with sulfur-containing regulator regulated vulcanization network structure and a preparation method thereof. Specifically, the present application provides a method for preparing vulcanized rubber with sulfur-containing regulator regulated vulcanization network structure, which comprises vulcanizing 100 parts by weight of raw rubber in the presence of 0.5-2 parts by weight of sulfur-containing regulator, so as to obtain vulcanized rubber with high mechanical properties and anti-creep properties. The present application also provides a method for preparing vulcanized rubber with sulfur-containing regulator regulated vulcanization network structure, which comprises vulcanizing 100 parts by weight of raw rubber in the presence of 3-8 parts by weight of sulfur-containing regulator, so as to obtain vulcanized rubber with high mechanical properties and with recycling and self-healing properties. The present application realizes significant improvement of the performance of vulcanized rubber through a simple and easy-to-operate method, is very suitable for industrial application and popularization, and has excellent cost advantage.

Description

Technical Field

[0001] This invention belongs to the field of rubber technology, specifically relating to a vulcanized rubber with a vulcanization network structure regulated by a sulfur-containing regulator and its preparation method. Background Technology

[0002] Natural rubber (NR) is an important industrial raw material, widely used in the manufacture of tires, rubber products, and aerospace. While synthetic polyisoprene rubber (PIP) has a similar main chain structure and molecular weight to natural rubber, its properties are inferior, particularly in tensile strength, tear resistance, and fatigue resistance, significantly lagging behind natural rubber and severely limiting its practical application. Sulfur vulcanization, as an important rubber processing technology, can improve the overall performance, quality, and durability of products. However, it also presents significant challenges to repairing internal microcracks and recycling waste rubber. Waste rubber disposal has become a global environmental, social, and economic issue. Therefore, from the perspective of green chemistry and sustainable development, developing high-performance, recyclable, and self-healing rubber materials is crucial. This patent utilizes a sulfur-containing regulator to control the structure of the rubber vulcanization network, thereby preparing a high-performance, recyclable, and self-healing polyisoprene rubber. This is of great significance for expanding the application areas of polyisoprene rubber and promoting green and sustainable development. Summary of the Invention

[0003] This invention proposes a simple method for preparing high-performance modified vulcanized rubber by adjusting the composition and content of crosslinking bonds in the vulcanization network. On one hand, the high content of polysulfide bonds in the modified vulcanized rubber endows it with excellent SiC (SiO2) ability, thus achieving superior mechanical properties. On the other hand, we also prepare vulcanized rubber with self-healing and recyclable properties by introducing complete polysulfide bonds into the vulcanization network. The polysulfide bonds in the rubber sample can undergo rapid exchange reactions under temperature stimulation. This unique characteristic not only gives the crosslinked rubber excellent self-healing properties (self-healing efficiency of 89.8%), but also excellent recyclability (recovery rate of 104%).

[0004] Specifically, in a first aspect, the present invention provides a method for preparing a vulcanized rubber having a vulcanization network structure regulated by a sulfur-containing regulator, comprising vulcanizing 100 parts by weight of raw rubber in the presence of 0.5-2 parts by weight of a sulfur-containing regulator, thereby obtaining a vulcanized rubber with high mechanical properties and creep resistance.

[0005] Further, the raw rubber is at least one selected from ethylene propylene diene monomer (EPDM) rubber, natural rubber, styrene-butadiene rubber (SBR), cis-butadiene rubber (BR), polybutadiene rubber, butyl rubber, nitrile rubber, styrene / butadiene block copolymer, polyisoprene rubber, polynorbornene, unsaturated polyester rubber, epoxidized butadiene rubber, epoxidized isoprene rubber, epoxidized styrene / butadiene block copolymer, and epoxidized styrene / isoprene block copolymer. Preferably, the raw rubber is polyisoprene rubber.

[0006] Furthermore, the sulfur-containing regulator is a dimercapto compound.

[0007] Furthermore, the sulfur-containing regulator is selected from at least one of the following compounds:

[0008]

[0009] Further, the sulfur-containing regulator is at least one of, for example, benzene dithiol (BED), lipoic acid (LA), 4',4-dimercaptodiphenyl sulfide (TBBT), dithiothreitol (DTT), 4,4-diaminodiphenyl disulfide (APDS), 2,5-diamino-1,4-benzenedithiophenol dihydrochloride (DPDD), bis(4-aminophenyl) sulfide (TDA), p-toluene disulfide (PTD), 4-aminobenzenethiophenol, 3-aminobenzenethiophenol, 2-aminobenzenethiophenol, 4-(phenylthio)aniline, butanedithiol, and hexanedithiol.

[0010] Preferably, the sulfur-containing regulator is present in 0.5-1 parts by weight.

[0011] Furthermore, the method also includes adding 30-50 parts by weight of carbon black or silica.

[0012] Furthermore, the vulcanization process includes adding the vulcanizing agent using a two-roll mill or solution blending method, followed by vulcanization molding at high temperature.

[0013] Further, the vulcanizing agent is sulfur, tetramethylthiuram disulfide (TMTD), bis(pentamethylenethiuram) tetrasulfide (DPTT) (TRA), 4-(2-benzothiazolyldithio)morpholine (MDB), tetraethylthiuram disulfide (TETD), tetrabutylthiuram disulfide (TBTD), tetramethylthiuram tetrasulfide (TMTT), 4,4'-dimorpholine disulfide (DTDM), N,N-polythiobis(dimethylamine), N,N'-polythiobis(diethylamine), cycloheptasulfide The vulcanizing agent is at least one selected from imine, dicumyl peroxide (DCP), di-tert-butyl peroxide (DTBP), 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (DBPMH), benzoyl peroxide (BPO), 2,4-dichlorobenzoyl peroxide (DCPB), tert-butyl perbenzoate (TBPB), bis-tert-butylperoxyisopropylbenzene (BIPB), 3,3,5,7,7-pentamethyl-1,2,4-tricyclooxyhexane (PMTO), and cumyl hydroperoxide (CHP). Preferably, the vulcanizing agent is sulfur.

[0014] Furthermore, the vulcanization also includes the addition of additives, including zinc oxide, stearic acid, antioxidants, anti-aging agents and / or vulcanization accelerators.

[0015] Furthermore, the antioxidant can be N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine.

[0016] Furthermore, the antioxidant can be poly(1,2-dihydro-2,2,4-trimethylquinoline).

[0017] Furthermore, the vulcanization accelerator can be N-cyclohexyl-2-benzothiazole sulfonamide.

[0018] Furthermore, the amount of vulcanizing agent added is 1-3 parts by weight, preferably 2 parts.

[0019] Furthermore, the weight parts of zinc oxide, stearic acid, antioxidant, anti-aging agent and vulcanization accelerator added are 3-8 parts, 1-4 parts, 1-3 parts, 1-3 parts and 0.5-3 parts, respectively.

[0020] As described herein, the specific process for vulcanizing raw rubber using the vulcanizing agent and auxiliaries described in this invention is well known to those skilled in the art and can be conventionally adjusted. For example, the exemplary vulcanization process described in the embodiments of this specification or any other suitable process can be used. For example, the vulcanization conditions can be: hot pressing temperature of 120-190°C, for example 150-160°C; pressure of 7-20 MPa, for example 8-12 MPa; and time of 15-120 min, for example 20-40 min.

[0021] The present invention also provides a vulcanized rubber with high mechanical properties and creep resistance prepared by the method described above.

[0022] In a second aspect, the present invention provides a method for vulcanized rubber with a sulfur-containing modifier regulating the vulcanization network structure, comprising vulcanizing 100 parts by weight of raw rubber in the presence of 3-8 parts by weight of a sulfur-containing modifier, thereby obtaining vulcanized rubber with high mechanical properties and recyclability and self-healing properties.

[0023] Further, the raw rubber is at least one selected from ethylene propylene diene monomer (EPDM) rubber, natural rubber, styrene-butadiene rubber (SBR), cis-butadiene rubber (BR), polybutadiene rubber, butyl rubber, nitrile rubber, styrene / butadiene block copolymer, polyisoprene rubber, polynorbornene, unsaturated polyester rubber, epoxidized butadiene rubber, epoxidized isoprene rubber, epoxidized styrene / butadiene block copolymer, and epoxidized styrene / isoprene block copolymer. Preferably, the raw rubber is polyisoprene rubber.

[0024] Furthermore, the sulfur-containing regulator is a dimercapto compound.

[0025] Furthermore, the sulfur-containing regulator is selected from at least one of the following compounds:

[0026]

[0027] Further, the sulfur-containing regulator is at least one of, for example, benzene dithiol (BED), lipoic acid (LA), 4',4-dimercaptodiphenyl sulfide (TBBT), dithiothreitol (DTT), 4,4-diaminodiphenyl disulfide (APDS), 2,5-diamino-1,4-benzenedithiophenol dihydrochloride (DPDD), bis(4-aminophenyl) sulfide (TDA), p-toluene disulfide (PTD), 4-aminobenzenethiophenol, 3-aminobenzenethiophenol, 2-aminobenzenethiophenol, 4-(phenylthio)aniline, butanedithiol, and hexanedithiol.

[0028] Furthermore, the method also includes adding 30-50 parts by weight of carbon black or silica.

[0029] Furthermore, the vulcanization process includes adding the vulcanizing agent using a two-roll mill or solution blending method, followed by vulcanization molding at high temperature.

[0030] Further, the vulcanizing agent is sulfur, tetramethylthiuram disulfide (TMTD), bis(pentamethylenethiuram) tetrasulfide (DPTT) (TRA), 4-(2-benzothiazolyldithio)morpholine (MDB), tetraethylthiuram disulfide (TETD), tetrabutylthiuram disulfide (TBTD), tetramethylthiuram tetrasulfide (TMTT), 4,4'-dimorpholine disulfide (DTDM), N,N-polythiobis(dimethylamine), N,N'-polythiobis(diethylamine), cycloheptasulfide The vulcanizing agent is at least one selected from imine, dicumyl peroxide (DCP), di-tert-butyl peroxide (DTBP), 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane (DBPMH), benzoyl peroxide (BPO), 2,4-dichlorobenzoyl peroxide (DCPB), tert-butyl perbenzoate (TBPB), bis-tert-butylperoxyisopropylbenzene (BIPB), 3,3,5,7,7-pentamethyl-1,2,4-tricyclooxyhexane (PMTO), and cumyl hydroperoxide (CHP). Preferably, the vulcanizing agent is sulfur.

[0031] Furthermore, the vulcanization also includes the addition of additives, including zinc oxide, stearic acid, antioxidants, anti-aging agents and / or vulcanization accelerators.

[0032] Furthermore, the antioxidant can be N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine.

[0033] Furthermore, the antioxidant can be poly(1,2-dihydro-2,2,4-trimethylquinoline).

[0034] Furthermore, the vulcanization accelerator can be N-cyclohexyl-2-benzothiazole sulfonamide.

[0035] Furthermore, the amount of vulcanizing agent added is 1-3 parts by weight, preferably 2 parts.

[0036] Furthermore, the weight parts of zinc oxide, stearic acid, antioxidant, anti-aging agent and vulcanization accelerator added are 3-8 parts, 1-4 parts, 1-3 parts, 1-3 parts and 0.5-3 parts, respectively.

[0037] Preferably, the amount of vulcanization accelerator added is 1 part by weight.

[0038] As described herein, the specific process for vulcanizing raw rubber using the vulcanizing agent and auxiliaries of this invention is well known to those skilled in the art and can be conventionally adjusted. For example, the exemplary vulcanization process described in the embodiments of this specification or any other suitable process can be used. For example, the vulcanization conditions can be: hot pressing temperature of 120-190°C, for example 150-160°C; pressure of 7-20 MPa, for example 8-12 MPa; and time of 15-120 min, for example 20-40 min.

[0039] The present invention also provides a self-healing and recyclable vulcanized rubber prepared by the method described above.

[0040] Beneficial effects of the present invention

[0041] This invention has discovered that, during the vulcanization of raw rubber (e.g., polyisoprene rubber), the composition and content of crosslinking bonds in the vulcanization network can be adjusted simply by adding a specific proportion of sulfur-containing modifier, thereby preparing high-performance modified vulcanized rubber. On one hand, the higher polysulfide content in the modified vulcanized rubber endows it with excellent SiC (sulfur-in-carbon) ability, resulting in superior mechanical properties. On the other hand, by introducing complete polysulfide bonds into the vulcanization network, vulcanized rubber with self-healing and recyclable properties can also be prepared. The polysulfide bonds in the rubber sample can undergo rapid exchange reactions under temperature stimulation. This unique characteristic not only gives the crosslinked rubber excellent self-healing properties (self-healing efficiency of 89.8%) but also excellent recyclability (recovery rate of 104%).

[0042] This invention achieves significant improvement in the performance of vulcanized rubber through a simple and easy-to-operate method, making it very suitable for industrial applications and promotion, and offering excellent cost advantages. Attached Figure Description

[0043] Figure 1 The vulcanization curves of (a) BED-x and (b) BTD-x samples at 143 °C are shown. (c) The T90 and ΔS values ​​of BED-x and BTD-x samples are shown. (e) The crosslinking density, swelling ratio, and gel fraction of BED-x and (f) BTD-x samples are shown.

[0044] Figure 2 The DSC curves for (a) BED-x sample and (b) BTD-x sample are shown.

[0045] Figure 3 The Fourier transform infrared spectra of (a) BED-x and (b) BTD-x samples are shown. The content of disulfide and polysulfide bonds in (c) BED-x and (d) BTD-x samples is also shown.

[0046] Figure 4 The stress-strain curves for (a) BED-x and (b) BTD-x samples are shown. (c) The stress-strain curve for the representative sample with the best mechanical properties. (d) The tensile strength, toughness, and tear strength of the representative sample. (e) The Mooney-Rivlin curves for the representative sample. (f) The fitted values ​​of Gc and Ge.

[0047] Figure 5The WAXD plots of (a) PIP and (b) BED-1 samples under different strains are shown. (c) A magnified image of the WAXD plot. (d) The fitted curve of PIP at maximum strain. (e) The crystallinity index of PIP, BED-0.5, BED-1 and BTD-0.125 samples as a function of strain.

[0048] Figure 6 Storage modulus and tanδ curves of (a) PIP, BED-0.5, BED-1, and BTD-0.125 samples are shown. Creep and recovery curves of PIP, BED-0.5, BED-1, and BTD-0.125 samples at (b) 30℃, (c) 60℃, (d) 90℃, (e) 120℃, and (f) 150℃ are also shown.

[0049] Figure 7 The following data are shown: (a) the vulcanization curve of the BED-xy sample at 143 °C; (b) the T90 and ΔS values ​​of the BED-xy sample; (c) the crosslinking density, swelling ratio, and gel fraction of the BED-x-1 and (d) BED-x-1.5 samples.

[0050] Figure 8 The following are displayed: (a) Fourier transform infrared spectra of the BED-xy sample; (b) the content of monosulfide, disulfide, and polysulfide bonds in the BED-xy sample; (c) Fourier transform infrared spectra of BED-4-1 and the corresponding recovered sample; and (d) Fourier transform infrared spectra of BED-5-1 and the corresponding recovered sample.

[0051] Figure 9 The following figures are shown: (a) Stress-strain curves of the BED-xy sample; (b) Tensile strength, toughness, and fracture strain of the BED-xy sample; and (c) Creep and recovery curves of the BED-xy sample at 30°C and (d) 90°C.

[0052] Figure 10 The stress relaxation curves of (a) BED-4-1, (b) BED-5-1, and (c) BED-3-1.5 samples at different temperatures are shown. (d) Arrhenius plots derived from the relaxation time τ at different temperatures are shown. (e) Activation energy (Ea) of the BED-xy sample is shown. (f) Thermal expansion coefficient of the BED-xy sample is shown by expansion coefficient test.

[0053] Figure 11 The following images are shown: (a) photographs of the BED-4-1 sample before and after healing, and the healing film after twisting and stretching. (b) stress-strain curves of the BED-4-1 and (c) BED-3-1.5 samples before and after healing. (d) Heating efficiency of the BED-xy sample after healing at 170°C for 30 minutes.

[0054] Figure 12 Optical microscopic images of BED-4-1 and BED-3-1.5 samples before healing (a, c) and after healing (b, d) are shown.

[0055] Figure 13 The following figures are shown: (a) Schematic diagram of the recovery process of the BED-xy sample; (b) Stress-strain curves of the recovered BED-4-1 sample and the original BED-4-1 sample; (c) Stress-strain curves of the recovered sample and the original BED-3-1.5 sample; (d) and (e) Mechanical property recovery rates of the BED-xy samples after 1 hour and 2 hours of recovery.

[0056] Figure 14 The stress-strain curves for adding different sulfur-containing modifiers are shown: (a) lipoic acid (LA), (b) 4',4-dimercaptodiphenyl sulfide (TBBT), (c) dithiothreitol (DTT), (d) 4,4-diaminodiphenyl disulfide (APDS), (e) 2,5-diamino-1,4-benzenedithiophenol dihydrochloride (DPDD), (f) bis(4-aminophenyl) sulfide (TDA), and (g) p-toluene disulfide (PTD).

[0057] Figure 15 The vulcanization curves of polyisoprene rubber with different vulcanization regulators are shown: (a) 4-aminobenzylthiophenol, (b) 4-aminobenzylthiophenol and 40 parts carbon black (CB), (c) 3-aminobenzylthiophenol, (d) 3-aminobenzylthiophenol and 40 parts carbon black, (e) 3-aminobenzylthiophenol, and (f) 2-aminobenzylthiophenol and 40 parts carbon black.

[0058] Figure 16 The stress-strain curves of polyisoprene rubber with different vulcanization modifiers are shown: (a) 4-aminobenzylthiophenol, (b) 4-aminobenzylthiophenol and 40 parts carbon black (CB), (c) 3-aminobenzylthiophenol, (d) 3-aminobenzylthiophenol and 40 parts carbon black, (e) 3-aminobenzylthiophenol, and (f) 2-aminobenzylthiophenol and 40 parts carbon black.

[0059] Figure 17 The vulcanization curves of styrene-butadiene rubber and butadiene rubber with different amounts of vulcanization regulators are shown: (a) styrene-butadiene rubber and (b) butadiene rubber.

[0060] Figure 18 The stress-strain curves of styrene-butadiene rubber and butadiene rubber with different amounts of vulcanization modifiers are shown: (a) styrene-butadiene rubber and (b) butadiene rubber. Detailed Implementation

[0061] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0062] The raw materials used in the embodiments of this invention are:

[0063] Polyisoprene rubber (referred to as PIP in this specification) is grade IR70. Styrene-butadiene rubber is grade YH2605, and cis-butadiene rubber was prepared in the laboratory. Sulfur, vulcanization accelerator CBS (N-cyclohexyl-2-benzothiazole sulfonamide), antioxidant TMQ (poly(1,2-dihydro-2,2,4-trimethylquinoline)), antioxidant 4020 (N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine), zinc oxide (ZnO), and stearic acid (SA) were purchased from Adamas Chemical.

[0064] The following examples demonstrate the preparation of samples using a two-roll open mill method. The specific operating steps are as follows:

[0065] 1. Pass the polyisoprene rubber thin film through the rollers 3-6 times using an appropriate roller gap;

[0066] 2. Add ZnO and SA and pass through a thin tube 3-6 times;

[0067] 3. Add TMQ and antioxidant 4020 and mix 3-5 times, then add fillers such as benzene dithiol (BED) and butanediol (BTD) and pass through the mixture 3-6 times.

[0068] 4. Add sulfur and CBS and pass through a sieve 3-6 times;

[0069] 5. Scrape the medicine off the double rollers and pass it through the tube 5-8 times with the minimum roller gap.

[0070] The vulcanization process used in the following examples is as follows: using a flat vulcanizer, the hot pressing vulcanization time is determined according to T90 at 143°C and 10MPa pressure, and high-temperature vulcanization molding is performed.

[0071] Example 1

[0072] A modified vulcanized rubber was prepared using a two-roll milling process, and the specific steps are as follows.

[0073] 1. Using a suitable roller gap, pass 100 parts by weight of polyisoprene rubber through a thin tube 5 times.

[0074] 2. Add 5 parts by weight of ZnO and 2 parts by weight of SA and pass through a thin tube 5 times.

[0075] 3. Add 1 part by weight of TMQ and antioxidant 4020 and mix 3-5 times, then add 0.125 parts by weight of benzenedithiol (BED) and pass through 5 times.

[0076] 4. Add 2 parts by weight of sulfur and 1 part by weight of CBS and pass through the tube 5 times.

[0077] 5. Scrape the medicine off the double rollers and pass it through the tube 5 times with the minimum roller gap.

[0078] The resulting product was named BED-0.125.

[0079] Example 2

[0080] A modified vulcanized rubber was prepared using a two-roll mill, the preparation method being the same as described in Example 1, except that the amount of benzenedithiol (BED) added was 0.25 parts by weight. The resulting product was named BED-0.25.

[0081] Example 3

[0082] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method being the same as described in Example 1, except that the amount of benzenedithiol (BED) added was 0.5 parts by weight. The resulting product was named BED-0.5.

[0083] Example 4

[0084] A modified vulcanized rubber was prepared using a two-roll mill, the preparation method being the same as described in Example 1, except that the amount of benzenedithiol (BED) added was 1 part by weight. The resulting product was named BED-1.

[0085] Example 5

[0086] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method being the same as described in Example 1, except that the amount of benzenedithiol (BED) added was 2 parts by weight. The resulting product was named BED-0.2.

[0087] Example 6

[0088] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method of which was the same as that described in Example 1, except that in step 3, 0.125 parts by weight of butanedithiol (BTD) was used instead of benzenedithiol (BED). The resulting product was named BTD-0.125.

[0089] Example 7

[0090] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method of which was the same as that described in Example 1, except that in step 3, 0.25 parts by weight of butanedithiol (BTD) was used instead of benzenedithiol (BED). The resulting product was named BTD-0.25.

[0091] Example 8

[0092] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method of which was the same as that described in Example 1, except that in step 3, 0.5 parts by weight of butanedithiol (BTD) was used instead of benzenedithiol (BED). The resulting product was named BTD-0.5.

[0093] Example 9

[0094] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method of which was the same as that described in Example 1, except that in step 3, 1 part by weight of butanedithiol (BTD) was used instead of benzenedithiol (BED). The resulting product was named BTD-1.

[0095] Example 10

[0096] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method of which was the same as that described in Example 1, except that in step 3, 2 parts by weight of butanedithiol (BTD) were used instead of benzenedithiol (BED). The resulting product was named BTD-2.

[0097] Example 11

[0098] A modified vulcanized rubber was prepared using a two-roll milling process, and the specific steps are as follows.

[0099] 1. Using a suitable roller gap, pass 100 parts by weight of polyisoprene rubber through a thin tube 5 times.

[0100] 2. Add 5 parts by weight of ZnO and 2 parts by weight of SA and pass through a thin tube 5 times.

[0101] 3. Add 1 part by weight of TMQ and antioxidant 4020 and mix 3-5 times, then add 3 parts by weight of benzenedithiol (BED) and pass through 5 times.

[0102] 4. Add 2 parts by weight of sulfur and 1 part by weight of CBS and pass through the tube 5 times.

[0103] 5. Scrape the medicine off the double rollers and pass it through the tube 5 times with the minimum roller gap.

[0104] The resulting product was named BED-3-1.

[0105] Example 12

[0106] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method being the same as described in Example 11, except that the amount of benzenedithiol (BED) added was 4 parts by weight. The resulting product was named BED-4-1.

[0107] Example 13

[0108] A modified vulcanized rubber was prepared using a two-roll mill, the preparation method being the same as described in Example 11, except that the amount of benzenedithiol (BED) added was 5 parts by weight. The resulting product was named BED-5-1.

[0109] Example 14

[0110] A modified vulcanized rubber was prepared using a two-roll mill, the preparation method being the same as described in Example 11, except that the amount of CBS added was 1.5 parts by weight. The resulting product was named BED-3-1.5.

[0111] Example 15

[0112] A modified vulcanized rubber was prepared using a two-roll mill, the preparation method being the same as described in Example 12, except that the amount of CBS added was 1.5 parts by weight. The resulting product was named BED-4-1.5.

[0113] Example 16

[0114] A modified vulcanized rubber was prepared using a two-roll mill, the preparation method being the same as described in Example 13, except that the amount of CBS added was 1.5 parts by weight. The resulting product was named BED-5-1.5.

[0115] Example 17

[0116] A modified vulcanized rubber was prepared using a two-roll mill, the preparation method being the same as described in Example 1, except that thioctic acid (LA) was used instead of benzenedithiol, and the amount added was 0.5 parts by weight. The resulting product was named LA-0.5.

[0117] Example 18

[0118] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method being the same as described in Example 1, except that thioctic acid (LA) was used instead of benzenedithiol, and the amount added was 1 part by weight. The resulting product was named LA-1.

[0119] Example 19

[0120] A modified vulcanized rubber was prepared using a two-roll mill, the preparation method being the same as described in Example 1, except that 4',4-dimercaptodiphenyl sulfide (TBBT) was used instead of benzenedithiol, with an addition amount of 0.5 parts by weight. The resulting product was named TBBT-0.5.

[0121] Example 20

[0122] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method being the same as described in Example 1, except that 4',4-dimercaptodiphenyl sulfide (TBBT) was used instead of benzenedithiol, with an addition amount of 1 part by weight. The resulting product was named TBBT-1.

[0123] Example 21

[0124] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method of which was the same as that described in Example 1, except that dithiothreitol (DTT) was used instead of benzenedithiol, and the amount added was 1 part by weight. The resulting product was named DTT-1.

[0125] Example 22

[0126] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method of which was the same as described in Example 1, except that 4,4-diaminodiphenyl disulfide (APDS) was used instead of benzenedithiol, and the amount added was 0.5 parts by weight. The resulting product was named APDS-0.5.

[0127] Example 23

[0128] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method of which was the same as that described in Example 1, except that 4,4-diaminodiphenyl disulfide (APDS) was used instead of benzenedithiol, and the amount added was 1 part by weight. The resulting product was named APDS-1.

[0129] Example 24

[0130] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method being the same as described in Example 1, except that 2,5-diamino-1,4-benzenedithiophenol dihydrochloride (DPDD) was used instead of benzenedithiol, with an addition amount of 0.5 parts by weight. The resulting product was named DPDD-0.5.

[0131] Example 25

[0132] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method being the same as described in Example 1, except that 2,5-diamino-1,4-benzenedithiophenol dihydrochloride (DPDD) was used instead of benzenedithiol, with an addition amount of 1 part by weight. The resulting product was named DPDD-1.

[0133] Example 26

[0134] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method of which was the same as that described in Example 1, except that bis(4-aminophenyl) sulfide (TDA) was used instead of benzenedithiol, and the amount added was 0.5 parts by weight. The resulting product was named TDA-0.5.

[0135] Example 27

[0136] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method being the same as described in Example 1, except that bis(4-aminophenyl) sulfide (TDA) was used instead of benzenedithiol, and the amount added was 1 part by weight. The resulting product was named TDA-1.

[0137] Example 28

[0138] A modified vulcanized rubber was prepared using a two-roll mill, the preparation method being the same as described in Example 1, except that p-toluene disulfide (PTD) was used instead of benzene dithiol, and the amount added was 0.5 parts by weight. The resulting product was named PTD-0.5.

[0139] Example 29

[0140] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method being the same as described in Example 1, except that p-toluene disulfide (PTD) was used instead of benzene dithiol, and the amount added was 1 part by weight. The resulting product was named PTD-1.

[0141] Example 30

[0142] A modified vulcanized rubber was prepared using a two-roll mill, the preparation method being the same as described in Example 1, except that 4-aminothiophenol was used instead of benzenedithiol, and the amount added was 0.5 parts by weight. The resulting product was named PIP-d-ABTH-0.5phr.

[0143] Example 31

[0144] A modified vulcanized rubber was prepared using a two-roll mill, the preparation method being the same as described in Example 1, except that 4-aminothiophenol was used instead of benzenedithiol, and the amount added was 1 part by weight. The resulting product was named PIP-d-ABTH-1phr.

[0145] Example 32

[0146] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method being the same as described in Example 1, except that 4-aminothiophenol was used instead of benzenedithiol, and the amount added was 2 parts by weight. The resulting product was named PIP-d-ABTH-2phr.

[0147] Example 33

[0148] A modified vulcanized rubber was prepared using a two-roll mill method, the preparation method being the same as described in Example 1, except that 4-aminothiophenol was used instead of benzenedithiol, and the amount added was 5 parts by weight. The resulting product was named PIP-d-ABTH-5phr.

[0149] Example 34

[0150] A modified vulcanized rubber was prepared using a two-roll milling method, which was the same as that described in Example 30, except that 40 parts of carbon black (CB) were added. The resulting product was named PIP-d-ABTH-0.5phr-CB40.

[0151] Example 35

[0152] A modified vulcanized rubber was prepared using a two-roll milling method, which was the same as that described in Example 31, except that 40 parts of carbon black (CB) were added. The resulting product was named PIP-d-ABTH-1phr-CB40.

[0153] Example 36

[0154] A modified vulcanized rubber was prepared using a two-roll milling method, which was the same as that described in Example 32, except that 40 parts of carbon black (CB) were added. The resulting product was named PIP-d-ABTH-2phr-CB40.

[0155] Example 37

[0156] A modified vulcanized rubber was prepared using a two-roll milling method, which was the same as that described in Example 33, except that 40 parts of carbon black (CB) were added. The resulting product was named PIP-d-ABTH-5phr-CB40.

[0157] The procedure for adding 3-aminothiophenol and 2-aminothiophenol is similar to that in Examples 30-37 and will not be repeated here.

[0158] Example 38

[0159] A modified vulcanized rubber was prepared using a two-roll milling process, and the specific steps are as follows.

[0160] 1. Use a suitable roller gap to pass 100 parts by weight of styrene-butadiene rubber through a thin pass 5 times.

[0161] 2. Add 5 parts by weight of ZnO and 2 parts by weight of SA and pass through a thin tube 5 times.

[0162] 3. Add 1 part by weight of TMQ and antioxidant 4020 and mix 3-5 times, then add 0.5 parts by weight of benzene dithiol (BED) and pass through 5 times.

[0163] 4. Add 2 parts by weight of sulfur and 1 part by weight of CBS and pass through the tube 5 times.

[0164] 5. Scrape the medicine off the double rollers and pass it through the tube 5 times with the minimum roller gap.

[0165] The resulting product was named SBR-0.5phr.

[0166] The steps for preparing modified vulcanized rubber containing other parts of benzenedithiol are similar to those in this embodiment and will not be repeated here.

[0167] Example 39

[0168] A modified vulcanized rubber was prepared using a two-roll milling process, and the specific steps are as follows.

[0169] 1. Using a suitable roller gap, pass 100 parts by weight of butadiene rubber through a thin pass 5 times.

[0170] 2. Add 5 parts by weight of ZnO and 2 parts by weight of SA and pass through a thin tube 5 times.

[0171] 3. Add 1 part by weight of TMQ and antioxidant 4020 and mix 3-5 times, then add 0.5 parts by weight of benzene dithiol (BED) and pass through 5 times.

[0172] 4. Add 2 parts by weight of sulfur and 1 part by weight of CBS and pass through the tube 5 times.

[0173] 5. Scrape the medicine off the double rollers and pass it through the tube 5 times with the minimum roller gap.

[0174] The resulting product was named BR-0.5phr.

[0175] The steps for preparing the modified vulcanized rubber containing other parts of benzenedithiol are the same as in Example 39, and will not be repeated here.

[0176] Test case

[0177] Test methods

[0178] The vulcanization curve was characterized using an RPA8000 rubber processing analyzer; the tensile test was conducted using an INSTRON68TM-10 from the USA, with a tensile rate of 100 mm / min.

[0179] The DCS(Q200,TA) test is used to observe the exothermic chemical reaction during the sample heating process. The heating rate is 3℃ / min, the crucible is aluminum, and the sample mass is 5-7mg.

[0180] The content of monosulfide bonds, disulfide bonds, and polysulfide bonds in vulcanized rubber was determined by chemical probe method:

[0181] 1. After fully swelling the sample in toluene, dry it and determine the crosslinking density (Xtotal).

[0182] 2. After determining the crosslinking density (Xtotal), the sample is placed in toluene and allowed to swell fully. Then, isopropanethiol and piperidine are added, and swelling continues for 4 hours to break the polysulfide bonds. The sample is then removed, and the crosslinking density (X1) is determined using the equilibrium swelling method. The polysulfide bond ratio is then: (Xtotal - X1) / Xtotal.

[0183] 3. After determining the polysulfide bond ratio, the sample was placed in a pyridine solution of 1-hexanethiol for 48 hours to swell and break the disulfide bonds. Then, the sample was removed and the crosslinking density (X2) was determined using the equilibrium swelling method. The disulfide bond ratio was then calculated as (X1-X2) / Xtotal.

[0184] 4. After determining the disulfide bond ratio, the sample was placed in a toluene solution of iodomethane for 72 hours to swell, and then heated for another 96 hours to break the monosulfide bonds. Then, the sample was removed and the crosslinking density (X2) was determined using the equilibrium swelling method. The monosulfide bond ratio was (X2-X3) / Xtotal, and the carbon-carbon bond ratio was X3 / Xtotal.

[0185] FT-IR spectra were measured on a Nicoleti S10 in ATR-IR mode. In dynamic FTIR, the sample is fixed and pre-stretched to a predetermined strain before measurement.

[0186] Dynamic mechanical analysis (DMA) was performed using a Q800 (TA instrument); for temperature scanning mode, the sample was heated from -80°C to 150°C in tensile mode at a heating rate of 5°C / min, a frequency of 1Hz, and an amplitude of 15μm. For stress relaxation, the strain was maintained at 40%. Creep tests were conducted under a constant stress of 0.2MPa for 30 min, followed by a recovery period of 30 min. Stress relaxation was tested at temperatures of 110°C, 120°C, 130°C, and 140°C, with a strain of 5%.

[0187] Wide-angle X-ray diffraction (WAXD) was performed at the BL16B1 beamline of the Shanghai Synchrotron Radiation Facility (SSRF). The wavelength of the X-rays was 0.124 nm, and the atmospheric background was subtracted during sample processing. Rectangular samples were stretched using a self-made stretching machine at a stretching rate of 12.5 mm / min, and the signal was continuously acquired in situ using a MARCCD detector with an exposure time of 5 s. The distance from the sample to the detector was calibrated using CeO2, and the result was 187.5 mm.

[0188] Test Results

[0189] 1. Figure 1 The characterization results of the BED-x samples prepared in Examples 1-5 and the BTD-x samples prepared in Examples 6-10 are shown.

[0190] The crosslinking kinetics of the rubber samples were determined by monitoring the change in curing torque at 143℃. The optimal curing time (T90) is the time required for the torque to reach 90% of its maximum value. The torque difference (ΔS) is the difference between the maximum torque (MH) and the minimum torque (ML), representing the overall crosslinking density of the vulcanized rubber. It was found that adding small amounts of BED and BTD monomers significantly increased the vulcanization rate, with the maximum torque observed within 10 minutes as vulcanization progressed. This is because the -SH groups promote the vulcanization process, thereby accelerating the vulcanization speed. Furthermore, the maximum torque value of the BED-x sample continuously increased with increasing BED content, but excessive monomers reduced the torque. Figure 1 This is consistent with the results of the equilibrium expansion test. Figure 1 e). For example, the BED-2 sample exhibited the lowest torque and crosslinking density. Interestingly, the maximum torque value of the BTD-x sample decreased with increasing BTD content. This is because the -SH groups of the BTD monomer are more reactive than those of the BED monomer; excessive addition hinders the crosslinking reaction and reduces torque, which is consistent with the results of the equilibrium expansion test. Figure 1 f).

[0191] 2. Figure 2 The DSC curves of the BED-x samples prepared in Examples 1-5 and the BTD-x samples prepared in Examples 6-10 are shown.

[0192] DSC data revealed that only one Tg was observed when a low percentage of filler was added, while two Tgs appeared when a high percentage of filler was added, and the high Tgs were located very close to each other. We speculate that this may be because when a high percentage of filler is added, a high concentration of free radicals is formed in the filler aggregation area, which causes cis-isoprene to be converted into trans-isoprene, resulting in a new Tg peak at around 20 degrees.

[0193] 3. Figure 3 The Fourier transform infrared spectra and the contents of disulfide and polysulfide bonds of the BED-x samples prepared in Examples 1-5 and the BTD-x samples prepared in Examples 6-10 are shown.

[0194] Fourier transform infrared spectroscopy was used to analyze the types of crosslinking bonds. For example... Figure 3 As shown in a and 3b, 459cm -1 The absorption peaks at 619 cm⁻¹ correspond to the stretching vibrations of disulfide bonds (CSSC) and polysulfide bonds (C-SX-C), respectively, indicating the presence of disulfide and polysulfide bonds in the crosslinked system. Interestingly, we did not observe monosulfide bonds (CS) at 619 cm⁻¹. -1 and 1445cm -1 The absorption peak at that location indicates that there are no monosulfide bonds in the cross-linked sample.

[0195] We further analyzed the composition of crosslinking bonds in the vulcanization network using a chemical probe method. Crosslinked rubber samples were placed in a solution of 2-propanethiol and piperidine to break polysulfide bonds, thereby determining the polysulfide bond content. Dried crosslinked rubber samples were placed in a solution of 1-hexanethiol under argon atmosphere to break disulfide bonds, thereby determining the disulfide bond content. However, all crosslinked samples treated with 1-hexanethiol dissolved, indicating the absence of monosulfide bonds. This is consistent with the results of Fourier transform infrared spectroscopy. Figure 3 As shown in Figure c, the polysulfide bond content significantly increased after adding 0.5 phr and 1 phr of BED monomer. However, excessive BED monomer (BED-2) decreased the polysulfide bond content. Figure 3 As shown in Figure d, adding 0.125 phr of highly reactive BTD monomer significantly increases the polysulfide bond content. Conversely, adding excessive BTD monomer decreases the polysulfide bond content. Interestingly, adding 2 phr of BTD monomer (BTD-2) alters the crosslinking structure, with the crosslinking network consisting entirely of polysulfide bonds. These results confirm the type and content of crosslinks in the rubber samples.

[0196] 4. Figure 4 The mechanical property test results of the BED-x samples prepared in Examples 1-5 and the BTD-x samples prepared in Examples 6-10 are shown.

[0197] Typical tensile curves for BED-x and BTD-x samples are as follows: Figure 4 As shown in a and 4b. It is noteworthy that increasing the BED monomer content leads to significant changes in mechanical properties. Generally, increasing the BED monomer content improves tensile strength, tear strength, and toughness. The highest mechanical properties are obtained with 0.5 phr (BED-0.5) and 1 phr (BED-1) of BED monomer. However, excessive addition (BED-2) hinders the crosslinking reaction and reduces mechanical properties. Furthermore, the highest mechanical properties are obtained with 0.125 phr (BTD-0.125) of BTD monomer. However, increasing the BTD monomer content also leads to a decrease in tensile strength, tear strength, and toughness. The results from crosslinking density and torque (…) Figure 1 It can be seen that the addition of excessive monomers hinders the cross-linking reaction, leading to a decrease in mechanical properties. For example... Figure 4 As shown in c and 4d, we selected three samples with the best mechanical properties as representative samples for studying the reinforcement mechanism. Among them, the tensile strength, tear strength and toughness of BED-1 (30.4 MPa, 31.3 kN / m and 73.1 MJ / m3, respectively) are significantly higher than those of PIP (22.1 MPa, 25.7 kN / m and 47.1 MJ / m3, respectively).

[0198] like Figure 4As shown in equation e, to further understand the mechanism of mechanical property enhancement, we used the Mooney-Rivlin equation to estimate the entanglement network. It is generally believed that Gc is related to the permanent crosslinking network, while Ge is related to transient entanglement. Figure 4 f shows the fitted values ​​for Gc and Ge. It can be seen that the permanent modulus Gc and entanglement modulus Ge, representing the samples, are both higher than those of PIP. Notably, the entanglement modulus Ge values ​​of BED-0.5 and BED-1 are more than twice that of PIP, which significantly contributes to the improvement in mechanical properties. The Gc and Ge values ​​of BTD-0.125 are higher than PIP but lower than those of BED-0.5 and BED-1, therefore its mechanical properties are higher than PIP but lower than BED-0.5.

[0199] 5. Figure 5 The performance test results of samples BED-0.5, BED-1, and BTD-0.125 are shown.

[0200] Synchrotron radiation data revealed that BED-0.5 and BED-1 exhibited the lowest initial strain and highest crystallinity of SiC compared to PIP. Studies have shown that the initial strain of SiC is not related to the crosslinking density of the crosslinked network, but rather to entanglement and short chains. From Mooney-Rivlin results (… Figure 4 f) shows that the BED-0.5 and BED-1 samples have the highest entanglement modulus (Ge), therefore their initial SiC strain is the smallest. Meanwhile, chemical probe microanalysis (CPI) also shows... Figure 3 c) Our analysis revealed that the addition of BED monomer significantly increased the polysulfide bond content. This increased polysulfide bond content led to better molecular chain flexibility and enhanced SiC (SiC) capability, resulting in higher crystallinity for both BED-0.5 and BED-1 samples. Furthermore, the entanglement modulus (Ge) of the BTD-0.125 sample was only slightly higher than that of PIP, indicating similar initial SiC strains for both samples. However, the polysulfide bond content of BTD-0.125 (84.1%) was significantly higher than that of PIP (74.6%). Therefore, BTD-0.125 exhibited higher crystallinity, resulting in superior mechanical properties. However, the addition of excess monomer hindered the crosslinking reaction, reducing the polysulfide bond content and leading to a significant decrease in crystallinity. The excellent mechanical properties of BED-0.5 and BED-1 are precisely due to this outstanding SiC capability.

[0201] 6. Figure 6 The results of creep resistance tests for samples BED-0.5, BED-1, and BTD-0.125 are shown.

[0202] like Figure 6As shown in b-6f, representative samples exhibit a similar creep trend with increasing temperature, and dimensional stability begins to decline rapidly after 120℃. This is because the cross-links in the vulcanized network begin to exchange rapidly at this temperature. The BED-0.5 sample demonstrates excellent creep resistance, exhibiting the lowest creep strain and residual strain at all test temperatures compared to other rubber samples. This is likely due to its highest entanglement modulus. Figure 4 f). Topological entanglement severely restricts chain movement within the polymer network, acting as an anchor and thus optimizing dimensional stability. In contrast, the BTD-0.125 sample exhibited the worst creep performance across all temperatures. This is likely due to its highest polysulfide bond content. Figure 3 d) The low activation energy of polysulfide bonds leads to a rapid bond exchange rate, which is fatal to creep performance. Simultaneously, the entanglement modulus is much lower than that of the BED-0.5 sample. Overall, the BTD-0.125 sample exhibits the worst creep performance.

[0203] Based on the above analysis, we propose a simple method for preparing high-performance polyisoprene rubber by adjusting the composition and content of disulfide and polysulfide bonds and increasing the entanglement degree in the vulcanization network. Adding an appropriate amount of BED monomer can increase the polysulfide bond content and entanglement degree in the system, thereby improving the SiC (SiC) capability and significantly enhancing mechanical properties. Simultaneously, the high entanglement modulus also endows the sample with excellent dimensional stability.

[0204] To further explore the potential of BED monomers, we also prepared high-content BED monomer samples (i.e., Examples 11-16), which will be discussed in the following sections.

[0205] 7. Figure 7 The characterization results of the BED-xy samples prepared in Examples 11-16 are shown.

[0206] like Figure 7 As shown in 7a and 7b, at the same S / A ratio, the vulcanization rate and maximum torque significantly decrease with increasing BED monomer content. Meanwhile, at the same BED monomer content, adding additional accelerators significantly increases both the vulcanization rate and torque. This is because excessive monomer addition hinders the crosslinking reaction and reduces torque. This is consistent with the results of the equilibrium expansion test. Figure 7 (c and 7d). As the BED monomer content increased, the crosslinking density of the samples gradually decreased.

[0207] 8. Figure 8 The Fourier transform infrared spectra, disulfide and polysulfide bond content, and recovery performance tests of the BED-xy samples prepared in Examples 11-16 are shown.

[0208] Fourier transform infrared spectroscopy was used to analyze the types of crosslinking bonds. For example... Figure 8As shown in a, 451cm -1 The absorption peak at 619 cm⁻¹ corresponds to disulfide and polysulfide bonds. -1 and 1445cm -1 The absorption peaks at these locations correspond to monosulfide bonds. Interestingly, we did not observe absorption peaks for monosulfide bonds in samples BED-4-1 and BED-5-1. However, absorption peaks for all three types of crosslinking bonds were clearly observed in other samples. We further analyzed the composition of crosslinking bonds in the sulfurized network using chemical probe microanalysis. Figure 8 As shown in b, the vulcanization networks of samples BED-4-1 and BED-5-1 consist entirely of polysulfide bonds, containing no disulfide or monosulfide bonds. In other rubber samples, the vulcanization networks consist of three types of crosslinking bonds. However, the number of each type of crosslinking bond varies. This is consistent with the results of Fourier transform infrared spectroscopy. These results confirm the type and content of crosslinking bonds in the crosslinked rubber samples. Furthermore, we compared the Fourier transform infrared spectra of samples BED-4-1 and BED-5-1 before and after recycling. Figure 8 As shown in samples c and 8d, a significant monosulfide bond peak was observed after 2 hours of recovery at 170°C. Combined with the results of chemical probe testing, this is due to the continuous exchange of disulfide and polysulfide bonds during recovery, transforming them into monosulfide bonds. This results in a decrease in the content of disulfide and polysulfide bonds and an increase in the content of monosulfide bonds in the sulfide network. Samples BED-4-1 and BED-5-1 are entirely composed of polysulfide bonds in their sulfide networks, thus exhibiting excellent recyclability and self-healing properties.

[0209] 9. Figure 9 The mechanical properties and creep resistance test results of the BED-xy samples prepared in Examples 11-16 are shown.

[0210] Typical stress-strain curves for BED-xy are shown below. Figure 9 a. With the increase of BED monomer content, the tensile strength of the sample decreased slightly. Meanwhile, the addition of an additional accelerator significantly improved the tensile strength. This is based on the results of the vulcanization curve and equilibrium expansion experiment (…). Figure 7 Excessive addition of BED monomers can hinder the crosslinking reaction and reduce torque, resulting in a slight decrease in tensile strength. Although the addition of BED monomers slightly reduces tensile strength, the addition of appropriate amounts of BED monomers can change the composition of crosslinking bonds in the vulcanization network, giving the crosslinked rubber sample excellent recyclability and self-healing properties.

[0211] Dimensional stability is also a crucial property for recyclable and self-healing rubber elastomers. For example... Figure 9As shown in c and 9d, increasing the BED monomer content decreases creep performance because the addition of BED monomer increases the polysulfide bond content in the vulcanization network. Polysulfide bonds have a rapid bond exchange capacity, thus reducing creep performance. Simultaneously, increasing the BED monomer content decreases the crosslinking density, leading to a decline in creep performance. Furthermore, increasing the accelerator content decreases the polysulfide bond content and increases the monosulfide bond content and crosslinking density, thereby improving creep performance. Although the addition of BED monomer reduces creep performance, the material integrity is maintained at 90°C without cracking. This is crucial for the practical use of rubber products.

[0212] 10. Figure 10 Further test results of the performance of the BED-xy samples prepared in Examples 11-16 are shown.

[0213] Stress relaxation is an important characteristic of dynamic covalent polymer networks (DCPN) polymers. To investigate the stress relaxation rate and activation energy, we conducted stress relaxation experiments. Figure 10 As shown, the stress in all samples can relax to 1 / e of the initial stress within a certain time. Figure 10 As shown in Figure ac, all three samples exhibit significant stress release over time, indicating that the network can flow at the evaluation temperature. Furthermore, the BED-4-1 and BED-5-1 samples demonstrate faster relaxation rates and shorter characteristic relaxation times. For further analysis of stress relaxation behavior, [further details can be provided]. Figure 10 The slope of the fitted line in d is used to obtain the activation energy (Ea). Figure 10 The corresponding fitting parameters were summarized. The activation energies (Ea) of BED-4-1 (62.91 kJ / mol) and BED-5-1 (64.18 kJ / mol) were significantly lower than those of BED-3-1.5 (72.55 kJ / mol). This result indicates that samples BED-4-1 and BED-5-1 have advantages in post-processing. Monosulfide bonds have the highest bond energy, followed by disulfide bonds, while polysulfide bonds have the lowest bond energy. Combined with the results of chemical probe testing, the BED-4-1 sample has the lowest activation energy because it contains only polysulfide bonds, while the BED-3-1.5 sample contains the most monosulfide bonds, hence its highest activation energy. Furthermore, the topological transition temperature (Tv) was measured using dilution testing. Figure 10 As shown in f, with the increase of accelerator content, the crosslinking density and monosulfide bond content increase, leading to a rapid increase in Tv. Simultaneously, with the increase of BED monomer, the crosslinking density decreases, and the polysulfide bond content increases, resulting in a decrease in Tv. Above Tv, the exchange reaction accelerates strongly, and the topological structure rearranges. This phenomenon is also more beneficial for subsequent recovery and self-healing experiments.

[0214] 11. Figure 11 and 12The self-healing performance test results of the BED-xy samples prepared in Examples 11-16 are shown.

[0215] The self-healing ability test method involves cutting a rubber film into two pieces with a blade, then placing them together and allowing them to heal at 170°C for approximately 30 minutes. For better observation, one of the samples is painted black. Figure 11 As shown in figure a, the BED-4-1 sample can withstand large strains due to the remodeling of polysulfide bonds at the fracture interface. The self-healing efficiency was quantified by tensile testing. Figure 11 b and Figure 11 c shows representative stress-strain curves of BED-4-1 and BED-3-1.5 samples after healing at 170°C for 30 minutes. Figure 11 The healing efficiency parameters were summarized. Clearly, the healing efficiency of BED-4-1 tensile strength (89.8%) was significantly higher than that of BED-3-1.5 (15.4%). This is because the high crosslinking density not only restricts chain movement but also hinders the dynamic exchange of disulfide and polysulfide bonds to some extent. The BED-3-1.5 sample had the highest crosslinking density and the highest content of monosulfide bonds in its vulcanization network. Therefore, the BED-3-1.5 sample had the lowest healing efficiency. Furthermore, the BED-4-1 and BED-5-1 samples had suitable crosslinking densities, and their vulcanization networks were entirely composed of polysulfide bonds, thus exhibiting excellent self-healing properties.

[0216] In addition, a small scratch was made on the surface of the cross-linked rubber sample with a blade, and then the scratched rubber sample was placed in a vacuum oven at 170°C and baked for about 30 minutes. The healing process before and after the scratch healed was observed using an optical microscope. Optical microscope images are shown below. Figure 12 As shown, after approximately 30 minutes of repair at 170°C, the scratches on the BED-4-1 sample had healed, leaving only faint traces. However, the scratches on the BED-3-1.5 sample were clearly visible. Due to the presence of polysulfide bonds, the BED-4-1 sample exhibits excellent self-healing ability. The poor self-healing ability of BED-3-1.5 is attributed to the higher content of monosulfide bonds in the sulfurization network. These results are consistent with previous findings.

[0217] 12. Figure 13 The recovery performance test results of the BED-xy samples prepared in Examples 11-16 are shown.

[0218] Thermosetting materials, once fully cured, cannot be recycled. This leads to resource waste and environmental pollution. In rubber samples, disulfide and polysulfide bonds in the vulcanization network undergo exchange reactions under temperature stimulation. Cracks can reform during the dynamic rearrangement of the network, thus allowing cracked samples to recover their original properties, providing a possibility for the recycling and reprocessing of cross-linked rubber. Figure 13As shown in Figure a, the cross-linked rubber sample was cut into fragments and hot-pressed at 170°C for 1 or 2 hours to form a new coherent sample, demonstrating the recyclability of the BED-xy sample. The stress-strain curves of BED-4-1 and the recycled sample are shown in Figure a. Figure 13 b. Figure 13 d and 13e summarize the recovery parameters. For example... Figure 13 As shown in b, we found that the tensile strength of the BED-4-1 sample was the same as that of the original sample after 1 hour of recycling, demonstrating the excellent recyclability of the BED-4-1 sample. However, the elongation at break after recycling was significantly reduced. We speculate that the polysulfide bonds in the vulcanization network are continuously converted into monosulfide bonds through bond exchange, which reduces the flexibility of the molecular chains and increases the crosslinking density during cycling, thus leading to an increase in modulus and a decrease in elongation at break. Furthermore, we also found that the elongation at break increased after 2 hours of recycling. This is because the rubber sample underwent aging in a sustained high-temperature environment, resulting in a decrease in crosslinking density and thus an increase in elongation at break. This is also consistent with the results of the equilibrium swelling test. Figure 13 As shown in Figure c, the recyclability of sample BED-3-1.5 is very poor. This is because monosulfide bonds exist in the sulfur network, and effective bond exchange cannot be achieved during the recycling process. In summary, during the recycling process, disulfide bonds and polysulfide bonds continuously exchange and are converted into monosulfide bonds, thus sample BED-4-1 has excellent recyclability.

[0219] 13. Figure 14 The mechanical property test results of the rubber samples prepared in Examples 17-29 are shown.

[0220] It can be seen that adding different types of vulcanization modifiers with BED-like structures can significantly enhance the properties of rubber. This is of great significance for achieving the reinforcement of isoprene rubber through simple processing methods.

[0221] 14. Figure 15 The vulcanization curves of the samples after adding different vulcanization regulators are shown.

[0222] The data shows that the addition of vulcanization regulators can significantly improve the vulcanization rate.

[0223] 15. Figure 16 The mechanical property test results of samples with different vulcanization regulators are shown.

[0224] It can be seen that adding different types of vulcanization regulators with similar BED structures can also significantly enhance the properties of rubber.

[0225] 16. Figure 17 The results of vulcanization curves of styrene-butadiene rubber and cis-butadiene rubber after the addition of vulcanization regulators are shown.

[0226] Data shows that vulcanization regulators can significantly improve the vulcanization rate in different types of rubber.

[0227] 17. Figure 18 The mechanical properties of styrene-butadiene rubber and butadiene rubber after the addition of vulcanization regulators are shown.

[0228] It can be seen that adding different types of vulcanization modifiers with similar BED structures can not only enhance polyisoprene rubber but also significantly enhance the properties of other types of rubber.

[0229] Summarize

[0230] In this invention, we report a simple strategy for preparing high-performance polyisoprene rubber by adjusting the composition and content of crosslinks in the vulcanization network. Furthermore, we successfully prepared self-healing and recyclable polyisoprene rubber by further adjusting the crosslinks in the vulcanization network to consist entirely of polysulfide bonds. We investigated the composition and content of crosslinks in the polyisoprene rubber using Fourier transform infrared spectroscopy (FTIR) and chemical probe microanalysis. The tensile strengths of BED-0.5 (30.22 MPa) and BED-1 (30.42 MPa) significantly exceeded those of PIP (22.03 MPa) and were comparable to those of Malaysian NR. WAXD results showed that the high content of polysulfide bonds in the vulcanization network increased entanglement and improved SiC (SiC) capability, thus significantly improving mechanical properties. Simultaneously, the high degree of entanglement also endowed the rubber samples with excellent dimensional stability. Furthermore, introducing the entire polysulfide bond into the sulfurized network allows for topological rearrangement through rapid dynamic polysulfide bond exchange reactions at high temperatures, thereby endowing the BED-4-1 and BED-5-1 samples with self-healing capabilities and excellent recyclability. The representative sample exhibits a maximum self-healing efficiency of 89.8% and a tensile strength as high as 5.6 MPa.

[0231] It should be noted that while the preferred embodiments of the present invention are provided in this specification, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are not intended to impose additional limitations on the content of the present invention; their purpose is to provide a more thorough and comprehensive understanding of the disclosure of the present invention. Furthermore, the above-described technical features can be combined with each other to form various embodiments not listed above, all of which are considered to be within the scope of the present invention. Moreover, those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing vulcanized rubber with a vulcanization network structure regulated by a sulfur-containing regulator, characterized in that, This includes vulcanizing 100 parts by weight of raw rubber in the presence of a sulfur-containing regulator to obtain vulcanized rubber with high mechanical properties and creep resistance. The raw rubber is at least one of natural rubber, styrene-butadiene rubber, cis-butadiene rubber, nitrile rubber, and polyisoprene rubber; The sulfur-containing regulator is selected from: 0.5-1 parts by weight of , or 0.125, 0.25, or 0.5 parts by weight of butanedithiol, 0.5-1 part by weight of lipoic acid, 0.5-1 part by weight of 4',4-dimercaptodiphenyl sulfide, 1 part by weight of dithiothreitol, 0.5-1 part by weight of 2,5-diamino-1,4-benzenedithiophenol dihydrochloride or Or 0.5-1 parts by weight of bis(4-aminophenyl) sulfide; The vulcanization process includes adding a vulcanizing agent using a two-roll mill or solution blending method, followed by vulcanization molding at high temperature. The vulcanizing agent is at least one of sulfur, tetramethylthiuram disulfide, tetramethylpentamethylenethiuram tetrasulfide, 4-(2-benzothiazolyldithio)morpholine, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetramethylthiuram tetrasulfide, and 4,4'-dimorpholine disulfide.

2. The method according to claim 1, characterized in that, The method also includes adding 30-50 parts by weight of carbon black or silica.

3. The method according to claim 1, characterized in that, The vulcanization process also includes the addition of additives, including zinc oxide, stearic acid, antioxidants, and / or vulcanization accelerators.

4. The method according to claim 3, characterized in that, The antioxidant is poly(1,2-dihydro-2,2,4-trimethylquinoline). The vulcanization accelerator is N-cyclohexyl-2-benzothiazole sulfonamide.

5. The method according to claim 3, characterized in that, The vulcanization process also includes the addition of additives, including antioxidants.

6. The method according to claim 5, characterized in that, The antioxidant is N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine.

7. The method according to claim 1, characterized in that, The amount of vulcanizing agent added is 1-3 parts by weight.

8. The method according to claim 3, characterized in that, The added zinc oxide, stearic acid, antioxidant and vulcanization accelerator are added in weight proportions of 3-8 parts, 1-4 parts, 1-3 parts and 0.5-3 parts, respectively.

9. The method according to claim 5, characterized in that, The amount of antioxidant added is 1-3 parts by weight.

10. A vulcanized rubber with a vulcanization network structure regulated by a sulfur-containing regulator, characterized in that, Prepared by the method of any one of claims 1-9.

11. A method for preparing vulcanized rubber with a vulcanization network structure regulated by a sulfur-containing regulator, characterized in that, This includes vulcanizing 100 parts by weight of raw rubber in the presence of 4-5 parts by weight of a sulfur-containing modifier to obtain vulcanized rubber with high mechanical properties and recyclability and self-healing properties. The raw rubber is at least one of natural rubber and polyisoprene rubber; The sulfur-containing regulator is benzenedithiol; The vulcanization process includes adding a vulcanizing agent using a two-roll mill or solution blending method, followed by vulcanization molding at high temperature. The vulcanizing agent is at least one of sulfur, tetramethylthiuram disulfide, bispentamethylenethiuram tetrasulfide, 4-(2-benzothiazolyldithio)morpholine, tetraethylthiuram disulfide, tetrabutylthiuram disulfide, tetramethylthiuram tetrasulfide, and 4,4'-dimorpholine disulfide. The vulcanization process also includes the addition of an auxiliary agent, which includes a vulcanization accelerator. The vulcanization accelerator is N-cyclohexyl-2-benzothiazole sulfonamide, and the added vulcanization accelerator is 1 part by weight. The amount of vulcanizing agent added is 1-3 parts by weight.

12. The method according to claim 11, characterized in that, The method also includes adding 30-50 parts by weight of carbon black or silica.

13. The method according to claim 11, characterized in that, The vulcanization process also includes the addition of additives, including zinc oxide, stearic acid, and / or antioxidants.

14. The method according to claim 13, characterized in that, The vulcanization process also includes the addition of additives, including antioxidants.

15. The method according to claim 13, characterized in that, The weight parts of zinc oxide, stearic acid, and antioxidant added are 3-8 parts, 1-4 parts, and 1-3 parts, respectively.

16. The method according to claim 14, characterized in that, The amount of antioxidant added is 1-3 parts by weight.

17. The method according to claim 13, characterized in that, The antioxidant is poly(1,2-dihydro-2,2,4-trimethylquinoline).

18. The method according to claim 14, characterized in that, The antioxidant is N-1,3-dimethylbutyl-N'-phenyl-p-phenylenediamine.

19. A vulcanized rubber with a vulcanization network structure regulated by a sulfur-containing regulator, characterized in that, Prepared by the method of any one of claims 11-18.

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