A method for preparing high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal

Abstract

This invention relates to the field of reclaimed rubber preparation technology, specifically a method for preparing high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal. The preparation includes the following steps: S1. Anhydrous calcium sulfate and anhydrous ethanol are mixed and poured into a four-necked flask. After ultrasonication for 0.5 hours, the mixture is heated to 80°C in a water bath while stirring. A surface modifier is then added, and the mixture is heated for 5 hours. After centrifugation and washing, the final product is dried in a vacuum drying oven for 2 hours to obtain modified calcium sulfate whiskers; S2. Preparation of modified rice husk charcoal; S3. Modified calcium sulfate whiskers, modified rice husk charcoal, and reclaimed rubber are mixed using an open mill. After uniform mixing, the mixture is placed in a mold and pressed into sheets using a flat vulcanizing machine to obtain high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal. This invention utilizes the industrial byproduct calcium sulfate and agricultural waste rice husks as raw materials, which are pollution-free and recyclable. Through a green process, high-performance fillers are prepared, improving rubber performance while reducing production costs.

Description

Technical Field

[0001] This invention relates to the field of reclaimed rubber preparation technology, specifically to a method for preparing high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal. Background Technology

[0002] With the surge in global rubber product consumption, the annual production of waste rubber has exceeded 30 million tons (according to data from the International Rubber Research Organization). Its non-degradable nature leads to severe "black pollution." Reclaimed rubber, as a core pathway for resource recycling, continues to see increasing demand in tires, conveyor belts, and shock-absorbing materials. However, traditional reclaimed rubber faces three major technical bottlenecks: Insufficient mechanical properties: Rubber molecular chains break during regeneration, resulting in tensile strength (generally <10MPa), tear strength, and abrasion resistance significantly lower than virgin rubber, making it difficult to meet the demands of high-end engineering applications; Low filler reinforcement efficiency: Existing technologies largely rely on carbon black or silica as reinforcing agents. While carbon black can improve strength, its production energy consumption is high (over 1,500 kWh per ton) and it originates from non-renewable petroleum resources; while silica improves processability, it is prone to agglomeration and has poor dispersibility, requiring the use of silane coupling agents; A conflict between environmental friendliness and cost: Although biomass fillers are inexpensive, unmodified natural biochar has poor interfacial compatibility with the rubber matrix, easily causing stress concentration points and reducing material durability. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the purpose of this invention is to provide a method for preparing high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A method for preparing high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal includes the following preparation steps:

[0006] S1. According to the mass fraction, mix 2-5 parts of anhydrous calcium sulfate with 50-60 parts of anhydrous ethanol and pour the mixture into a four-necked flask. After ultrasonic cleaning for 0.5 hours, heat the mixture to 80°C in a water bath while stirring. Then add 5.8-7 parts of surface modifier and heat for 5 hours. After centrifugation and washing with anhydrous ethanol three times, the final product is dried in a vacuum drying oven for 2 hours to obtain modified calcium sulfate whiskers.

[0007] S2. Preparation of modified rice husk charcoal:

[0008] S21. The rice husk powder is separated from fine materials by using a sieve with a size of 60 mesh, and then calcined in a tube furnace at 650°C in a nitrogen atmosphere for 2 hours to obtain rice husk char.

[0009] S22. Place 3-5 parts of trimethyl borate in the upstream of a tube furnace, and place 90-100 parts of rice husk char obtained in step S21 in the constant temperature zone of the tube furnace. Purge with nitrogen and heat to 300°C at 5°C / min, then hold for 1 hour to obtain preliminarily modified rice husk char.

[0010] S23. Add the preliminarily modified rice husk char to 50-60 parts of the modification solution, add 1.5-3 parts of dopamine hydrochloride, stir at 400-450 r / min for 10-12 h at room temperature, collect the solid by centrifugation, wash with deionized water 3-4 times, and vacuum dry at 60℃ for 10-12 h to obtain modified rice husk char.

[0011] S3. Modified calcium sulfate whiskers, modified rice husk charcoal, and reclaimed rubber are mixed in an open mill. After the mixture is uniform, it is placed in a mold and pressed into sheets using a flat vulcanizing machine to obtain high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal.

[0012] Preferably, the preparation of the modified liquid includes the following steps:

[0013] S231. According to the mass fraction, add 0.8-1.5 parts of γ-aminopropyltriethoxysilane and 50-60 parts of anhydrous ethanol to 1.5-3 parts of 1-butyl-3-methylimidazolium tetrafluoroborate, and stir at 300-350 r / min for 10-15 min to obtain a preliminary modified solution.

[0014] S232. Add 5-10 parts of deionized water to the preliminary modified solution, stir at 40℃ for 25-30 minutes, then add 0.3-1 parts of trisodium citrate, and stir magnetically until completely dissolved to obtain the modified solution.

[0015] Preferably, the preparation of the surface modifier includes the following steps:

[0016] S11. According to the mass fraction, add 3.5-5 parts of KH560 and 0.5-1 parts to a three-necked flask, and stir at 300-350 r / min for 8-10 min under a 60℃ water bath and nitrogen protection.

[0017] S12. Slowly add 1-3 parts of epoxidized soybean oil, heat to 80℃ and react for 25-30 minutes to generate epoxid-siloxane prepolymer;

[0018] S13. Lower the temperature to 50℃, slowly add 0.8-1.5 parts of hexamethylene diisocyanate, and control the temperature to maintain at 63-67℃ for 1 hour to finally obtain the surface modifier.

[0019] Preferably, the ultrasonic frequency in step S1 is 40 kHz.

[0020] Preferably, the flow rate of nitrogen in step S22 is 50 mL / min.

[0021] Preferably, the recycled rubber in step S3 is selected from epoxidized natural rubber ENR-50.

[0022] Preferably, the mass ratio of modified calcium sulfate whiskers, modified rice husk charcoal, and reclaimed rubber in step S3 is 8-12:15-20:100.

[0023] Preferably, the stirring speed in step S232 is 400-450 r / min.

[0024] Preferably, the titanate coupling agent in step S11 is selected from LICA12.

[0025] Preferably, the dropping rate of hexamethylene diisocyanate in step S13 is 0.5 ml / min.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1. The mechanical properties of the high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal are significantly improved compared with pure waste rubber. The interfacial compatibility is significantly improved after adding modified calcium sulfate whiskers. At the same time, according to previous studies, adding modified calcium sulfate whiskers and rice husk charcoal can improve Mooney viscosity, which can meet the application requirements of specific engineering fields and high-performance reclaimed rubber.

[0028] 2. This invention utilizes the synergistic effect of modified calcium sulfate whiskers and modified rice husk charcoal to inhibit crack propagation through interfacial energy dissipation, resulting in a significant improvement in the tensile strength, tear strength, and elongation at break of the regenerated rubber compared to pure waste rubber. Simultaneously, the rubber compound is regenerated at room temperature using mechanical processing. On one hand, these chemical compounds break the chemical cross-linking bonds in the vulcanizate through chemical substitution reactions; on the other hand, they limit the damage to the rubber molecular backbone caused by oxidation, thereby restoring the plasticity of the compound and ensuring that the regenerated vulcanizate possesses good physical properties.

[0029] 3. This invention utilizes calcium sulfate, an industrial byproduct, and rice husks, an agricultural waste, as raw materials, which are characterized by being pollution-free and recyclable. High-performance fillers are prepared through green processes, which improve rubber performance while reducing production costs. The regeneration process is carried out at room temperature and pressure using an open mill or internal mixer to regenerate vulcanized rubber powder mixed with plant regeneration agents. The regeneration process is very convenient, pollution-free, and odorless, achieving the goal of environmentally friendly and green regeneration of rubber powder, which meets the requirements of sustainable development. Attached Figure Description

[0030] Figure 1 This is a process flow diagram for preparing high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal according to the present invention.

[0031] Figure 2The Fourier transform infrared spectrum of the high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk char obtained in Example 1 of the present invention is shown in a. a, b, and c are the Fourier transform infrared spectra of the surface modifier, anhydrous calcium sulfate, and modified calcium sulfate whiskers, respectively.

[0032] Figure 3 The XRD patterns of anhydrous calcium sulfate and modified calcium sulfate whiskers of this invention are shown below.

[0033] Figure 4 A schematic diagram showing the tensile strength of the recycled rubber obtained from pure waste rubber, Comparative Example 1, and Example 1 of this invention;

[0034] Figure 5 This is a diagram illustrating the dumbbell-shaped mechanical design of the present invention.

[0035] Figure 6 The Mooney viscosity results of the high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk char obtained in Example 1 of this invention are shown as a line graph. Detailed Implementation

[0036] The present invention will now be clearly and completely described in conjunction with embodiments thereof. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0037] Please see Figure 1-6 The present invention provides a technical solution:

[0038] Example 1

[0039] A method for preparing high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal:

[0040] Before preparing high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal, surface modifiers and modifying solutions are prepared:

[0041] The preparation of the modification solution includes the following steps:

[0042] S231. Add 8g of γ-aminopropyltriethoxysilane and 500ml of anhydrous ethanol to 15g of 1-butyl-3-methylimidazolium tetrafluoroborate, and stir at 300r / min for 10min to obtain a preliminary modified solution.

[0043] S232. Add 50 ml of deionized water to the preliminary modified solution, stir at 40°C for 25 min, then add 3 g of trisodium citrate, and stir magnetically until completely dissolved to obtain the modified solution.

[0044] The preparation of surface modifiers includes the following steps:

[0045] S11. Add 35g of KH560 and 5g of KH560 to a three-necked flask, and stir at 300r / min for 8min under a 60℃ water bath and nitrogen protection.

[0046] S12. Slowly add 10g of epoxidized soybean oil, heat to 80℃ and react for 25min to generate an epoxy-siloxane prepolymer;

[0047] S13. Lower the temperature to 50℃, slowly add 8g of hexamethylene diisocyanate, and control the temperature to 63℃ for 1 hour to finally obtain the surface modifier;

[0048] S1. Mix 20g of anhydrous calcium sulfate with 500ml of anhydrous ethanol and pour into a four-necked flask. After ultrasonic cleaning for 0.5h, heat to 80℃ in a water bath while stirring. Then add 58g of surface modifier and heat for 5h. After centrifugation three times, wash with anhydrous ethanol. Place the final product in a vacuum drying oven and dry for 2h to obtain modified calcium sulfate whiskers.

[0049] S2. Preparation of modified rice husk charcoal:

[0050] S21. The rice husk powder is separated from fine materials by using a sieve with a size of 60 mesh, and then calcined in a tube furnace at 650°C in a nitrogen atmosphere for 2 hours to obtain rice husk char.

[0051] S22. Place 30g of trimethyl borate in the upper part of a tube furnace, place 900g of rice husk char obtained in step S21 in the constant temperature zone of the tube furnace, pass nitrogen gas at a flow rate of 50mL / min, raise the temperature to 300℃ at 5℃ / min and hold for 1h to obtain preliminarily modified rice husk char.

[0052] S23. Add the preliminarily modified rice husk char to 500g of modification solution, control the pH to 8, add 15g of dopamine hydrochloride, stir at 400r / min for 10h at room temperature, collect the solid by centrifugation, wash with deionized water 3 times, and vacuum dry at 60℃ for 10h to obtain modified rice husk char.

[0053] S3. Mix 80g of modified calcium sulfate whiskers, 150g of modified rice husk charcoal, and 1000g of epoxidized natural rubber ENR-50 using an open mill. After the mixture is homogeneous, place it in a mold and press it into sheets using a flat vulcanizing machine to obtain high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal.

[0054] Example 2

[0055] A method for preparing high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal:

[0056] Before preparing high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal, surface modifiers and modifying solutions are prepared:

[0057] The preparation of the modification solution includes the following steps:

[0058] S231. Add 15g of γ-aminopropyltriethoxysilane and 600ml of anhydrous ethanol to 30g of 1-butyl-3-methylimidazolium tetrafluoroborate, and stir at 350r / min for 15min to obtain a preliminary modified solution.

[0059] S232. Add 100ml of deionized water to the preliminary modified solution, stir at 40℃ for 30min, then add 10g of trisodium citrate, and stir magnetically until completely dissolved to obtain the modified solution.

[0060] The preparation of surface modifiers includes the following steps:

[0061] S11. Add 50g of KH560 and 10g of KH560 to a three-necked flask and stir at 350r / min for 10min under a 60℃ water bath and nitrogen protection.

[0062] S12. Slowly add 30g of epoxidized soybean oil, heat to 80℃ and react for 30min to generate an epoxy-siloxane prepolymer;

[0063] S13. Lower the temperature to 50℃, slowly add 15g of hexamethylene diisocyanate, and control the temperature to 67℃ for 1 hour to finally obtain the surface modifier;

[0064] S1. Mix 50g of anhydrous calcium sulfate with 600ml of anhydrous ethanol and pour into a four-necked flask. Place the flask in an ultrasonic cleaner and sonicate for 0.5h. Then heat the flask to 80℃ in a water bath while stirring. Add 70g of surface modifier and heat for 5h. Centrifuge and wash the flask three times with anhydrous ethanol. Place the final product in a vacuum drying oven and dry for 2h to obtain modified calcium sulfate whiskers.

[0065] S2. Preparation of modified rice husk charcoal:

[0066] S21. The rice husk powder is separated from fine materials by using a sieve with a size of 60 mesh, and then calcined in a tube furnace at 650°C in a nitrogen atmosphere for 2 hours to obtain rice husk char.

[0067] S22. Place 50g of trimethyl borate in the upper part of a tube furnace, place 1000g of rice husk char obtained in step S21 in the constant temperature zone of the tube furnace, pass nitrogen gas at a flow rate of 50mL / min, raise the temperature to 300℃ at 5℃ / min and hold for 1h to obtain preliminarily modified rice husk char.

[0068] S23. Add the preliminarily modified rice husk char to 600g of modification solution, control the pH to 8.5, add 30g of dopamine hydrochloride, stir at 450r / min for 12h at room temperature, collect the solid by centrifugation, wash with deionized water 4 times, and vacuum dry at 60℃ for 12h to obtain modified rice husk char.

[0069] S3. Mix 120g of modified calcium sulfate whiskers, 200g of modified rice husk charcoal, and 1000g of epoxidized natural rubber ENR-50 using an open mill. After the mixture is homogeneous, place it in a mold and press it into sheets using a flat vulcanizing machine to obtain high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal.

[0070] Example 3

[0071] A method for preparing high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal:

[0072] Before preparing high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal, surface modifiers and modifying solutions are prepared:

[0073] The preparation of the modification solution includes the following steps:

[0074] S231. Add 10g of γ-aminopropyltriethoxysilane and 550ml of anhydrous ethanol to 20g of 1-butyl-3-methylimidazolium tetrafluoroborate, and stir at 320r / min for 11min to obtain a preliminary modified solution.

[0075] S232. Add 60 ml of deionized water to the preliminary modified solution, stir at 40°C for 27 min, then add 5 g of trisodium citrate, and stir magnetically until completely dissolved to obtain the modified solution.

[0076] The preparation of surface modifiers includes the following steps:

[0077] S11. Add 40g of KH560 and 6g of KH560 to a three-necked flask, and stir at 320r / min for 8-10min under a 60℃ water bath and nitrogen protection.

[0078] S12. Slowly add 20g of epoxidized soybean oil, heat to 80℃ and react for 27min to generate an epoxy-siloxane prepolymer;

[0079] S13. Lower the temperature to 50℃, slowly add 10g of hexamethylene diisocyanate, and control the temperature to 64℃ for 1 hour to finally obtain the surface modifier;

[0080] S1. Mix 30g of anhydrous calcium sulfate with 550ml of anhydrous ethanol and pour into a four-necked flask. Place the flask in an ultrasonic cleaner and sonicate for 0.5h. Then heat the flask to 80℃ in a water bath while stirring. Add 60g of surface modifier and heat for 5h. Centrifuge and wash the flask three times with anhydrous ethanol. Place the final product in a vacuum drying oven and dry for 2h to obtain modified calcium sulfate whiskers.

[0081] S2. Preparation of modified rice husk charcoal:

[0082] S21. The rice husk powder is separated from fine materials by using a sieve with a size of 60 mesh, and then calcined in a tube furnace at 650°C in a nitrogen atmosphere for 2 hours to obtain rice husk char.

[0083] S22. Place 40g of trimethyl borate in the upper part of a tube furnace, place 950g of rice husk char obtained in step S21 in the constant temperature zone of the tube furnace, pass nitrogen gas at a flow rate of 50mL / min, raise the temperature to 300℃ at 5℃ / min and hold for 1h to obtain preliminarily modified rice husk char.

[0084] S23. Add the preliminarily modified rice husk char to 550g of modification solution, control the pH to 8.2, add 20g of dopamine hydrochloride, stir at 420r / min for 11h at room temperature, collect the solid by centrifugation, wash with deionized water 3 times, and vacuum dry at 60℃ for 11h to obtain modified rice husk char.

[0085] S3. Mix 100g of modified calcium sulfate whiskers, 170g of modified rice husk charcoal, and 1000g of epoxidized natural rubber ENR-50 using an open mill. After the mixture is homogeneous, place it in a mold and press it into sheets using a flat vulcanizing machine to obtain high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal.

[0086] Example 4

[0087] A method for preparing high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal:

[0088] Before preparing high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal, surface modifiers and modifying solutions are prepared:

[0089] The preparation of the modification solution includes the following steps:

[0090] S231. Add 12g of γ-aminopropyltriethoxysilane and 580ml of anhydrous ethanol to 25g of 1-butyl-3-methylimidazolium tetrafluoroborate, and stir at 340r / min for 14min to obtain a preliminary modified solution.

[0091] S232. Add 80 ml of deionized water to the preliminary modified solution, stir at 40°C for 28 min, then add 8 g of trisodium citrate, and stir magnetically until completely dissolved to obtain the modified solution;

[0092] The preparation of surface modifiers includes the following steps:

[0093] S11. Add 45g of KH560 and 8g of KH560 to a three-necked flask, and stir at 340r / min for 9min under a 60℃ water bath and nitrogen protection.

[0094] S12. Slowly add 25g of epoxidized soybean oil, heat to 80℃ and react for 28min to generate an epoxy-siloxane prepolymer;

[0095] S13. Lower the temperature to 50℃, slowly add 14g of hexamethylene diisocyanate, and control the temperature to 65℃ for 1 hour to finally obtain the surface modifier;

[0096] S1. Mix 40g of anhydrous calcium sulfate with 580ml of anhydrous ethanol and pour into a four-necked flask. After ultrasonic cleaning for 0.5h, heat to 80℃ in a water bath while stirring. Then add 65g of surface modifier and heat for 5h. After centrifugation three times, wash with anhydrous ethanol. Place the final product in a vacuum drying oven and dry for 2h to obtain modified calcium sulfate whiskers.

[0097] S2. Preparation of modified rice husk charcoal:

[0098] S21. The rice husk powder is separated from fine materials by using a sieve with a size of 60 mesh, and then calcined in a tube furnace at 650°C in a nitrogen atmosphere for 2 hours to obtain rice husk char.

[0099] S22. Place 45g of trimethyl borate in the upper part of a tube furnace, place 980g of rice husk char obtained in step S21 in the constant temperature zone of the tube furnace, pass nitrogen gas at a flow rate of 50mL / min, raise the temperature to 300℃ at 5℃ / min and hold for 1h to obtain preliminarily modified rice husk char.

[0100] S23. Add the preliminarily modified rice husk char to 580g of modification solution, control the pH to 8.4, add 25g of dopamine hydrochloride, stir at 440r / min for 11.5h at room temperature, collect the solid by centrifugation, wash with deionized water 4 times, and vacuum dry at 60℃ for 11.5h to obtain modified rice husk char.

[0101] S3. Mix 110g of modified calcium sulfate whiskers, 180g of modified rice husk charcoal, and 1000g of epoxidized natural rubber ENR-50 using an open mill. After the mixture is homogeneous, place it in a mold and press it into sheets using a flat vulcanizing machine to obtain high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal.

[0102] Comparative Example 1

[0103] The only difference between Comparative Example 1 and Example 1 is that the addition of modified rice husk charcoal was omitted in Comparative Example 1, while the remaining steps are exactly the same in Comparative Example 1 and Example 1.

[0104] Performance testing:

[0105] A certain amount of the high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk char obtained in Example 1 was mixed with potassium bromide and ground into powder. The powder was then pressed into thin sheets using a tablet press and placed on a solid-state ATR spectrometer for spectral analysis. In OMNIC 9.2 software, standard ATR correction was used to eliminate spectral bandwidth distortion caused by the experimental properties of ATR. The obtained Fourier transform infrared spectra are attached. Figure 2 As shown in the figure, a, b, and c are the Fourier transform infrared spectra of the surface modifier, anhydrous calcium sulfate, and modified calcium sulfate whiskers, respectively. It can be seen from the figure that in b, the 3618 cm⁻¹... -1 3560cm -1 These are the OH stretching peaks of CSW. In c, 2947 and 2843 cm⁻¹ -1 The peaks between these peaks are related to the CH stretching vibrations of -CH3, -CH2, and -CH in the silane coupling agent, 852 cm⁻¹. -1 The nearby absorption peak is due to the Si-O asymmetric stretching vibration, 910 cm⁻¹. -1 The peak represents the stretching vibration of the epoxy groups on the surface modifier. The sample was thoroughly washed, completely eliminating physical adsorption, which proves the reaction between the surface modifier and the hydroxyl groups on the surface of anhydrous calcium sulfate. This indicates that the surface modifier and anhydrous calcium sulfate have successfully reacted. The above infrared analysis verifies that high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal has been successfully obtained.

[0106] Appendix Figure 3 The XRD patterns of anhydrous calcium sulfate and modified calcium sulfate whiskers of this invention are shown. Since the coating and grafting only occur on the surface of the whiskers and do not change the internal lattice structure and atomic arrangement, the characteristic peaks of the crystals do not change significantly after coating and grafting, proving that the surface modifier has no effect on the crystal structure of anhydrous calcium sulfate.

[0107] Appendix Figure 4 The diagram shows the tensile strength of the recycled rubber obtained from pure waste rubber, Comparative Example 1, and Example 1 of this invention. The high-performance recycled rubber based on modified calcium sulfate whiskers and rice husk charcoal obtained in Example 1 of this invention is significantly better than that of pure waste rubber and the recycled rubber obtained in Comparative Example 1, which proves that the high-performance recycled rubber based on modified calcium sulfate whiskers and rice husk charcoal obtained in this invention has better mechanical properties.

[0108] The high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal obtained in Example 1 was pressed into sheets using a flat vulcanizing machine and then cut into the following shapes. Figure 5 The dumbbell-shaped mechanical specimen shown is used to test mechanical properties, and the remaining portion after cutting is used to measure Mooney viscosity. Two circular pieces, 45-50 mm in diameter and 3-6 mm thick, are cut from the bubble-free rubber compound. One of the pieces has an 8 mm diameter hole punched in its center. The instrument is preheated to the set temperature (usually 100°C), and the specimen is placed in the mold cavity and isolated with cellophane. The preheating time is usually 1 minute to ensure uniform temperature. The rotor is started to rotate (standard speed 2 rpm), and the torque-time curve is recorded over 4 minutes. The results are expressed in ML. 100 ℃ 1+4 (M represents Mooney value, L represents the main rotor, and 1+4 represents 1 minute of preheating + 4 minutes of testing). (See attached image.) Figure 6 The graph shows the Mooney viscosity results of the high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal obtained in Example 1 of this invention. A, B, C, D, and E in the graph represent the Mooney viscosity at 10, 20, 30, 40, and 50 min, respectively. The graph shows that the Mooney viscosity of the high-performance reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal obtained in Example 1 gradually increases.

[0109] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for the preparation of reclaimed rubber based on modified calcium sulfate whiskers and rice husk char, characterized by, The preparation steps include the following: S1. According to the mass fraction, mix 2-5 parts of anhydrous calcium sulfate with 50-60 parts of anhydrous ethanol and pour the mixture into a four-necked flask. After ultrasonic cleaning for 0.5 hours, heat the mixture to 80°C in a water bath while stirring. Then add 5.8-7 parts of surface modifier and heat for 5 hours. After centrifugation and washing with anhydrous ethanol three times, the final product is dried in a vacuum drying oven for 2 hours to obtain modified calcium sulfate whiskers. S2. Preparation of modified rice husk charcoal: S21. The rice husk powder is separated from fine materials by using a sieve with a size of 60 mesh, and then calcined in a tube furnace at 650°C in a nitrogen atmosphere for 2 hours to obtain rice husk char. S22. Place 3-5 parts of trimethyl borate in the upstream of a tube furnace, and place 90-100 parts of rice husk char obtained in step S21 in the constant temperature zone of the tube furnace. Purge with nitrogen and heat to 300°C at 5°C / min, then hold for 1 hour to obtain preliminarily modified rice husk char. S23. Add the preliminarily modified rice husk char to 50-60 parts of the modification solution, add 1.5-3 parts of dopamine hydrochloride, stir at 400-450 r / min for 10-12 h at room temperature, collect the solid by centrifugation, wash with deionized water 3-4 times, and vacuum dry at 60℃ for 10-12 h to obtain modified rice husk char. S3. Modified calcium sulfate whiskers, modified rice husk charcoal, and reclaimed rubber are mixed in an open mill. After the mixture is uniform, it is placed in a mold and pressed into sheets using a flat vulcanizing machine to obtain reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal. The preparation of the modified liquid includes the following steps: S231. According to the mass fraction, add 0.8-1.5 parts of γ-aminopropyltriethoxysilane and 50-60 parts of anhydrous ethanol to 1.5-3 parts of 1-butyl-3-methylimidazolium tetrafluoroborate, and stir at 300-350 r / min for 10-15 min to obtain a preliminary modified solution. S232. Add 5-10 parts of deionized water to the preliminary modified solution, stir at 40℃ for 25-30 minutes, then add 0.3-1 parts of trisodium citrate, and stir magnetically until completely dissolved to obtain the modified solution. The preparation of the surface modifier includes the following steps: S11. According to the mass fraction, add 3.5-5 parts of KH560 to a three-necked flask and stir at 300-350 r / min for 8-10 min under a 60℃ water bath and nitrogen protection. S12. Slowly add 1-3 parts of epoxidized soybean oil, heat to 80℃ and react for 25-30 minutes to generate epoxy-siloxane prepolymer; S13. Lower the temperature to 50℃, slowly add 0.8-1.5 parts of hexamethylene diisocyanate, and control the temperature to maintain at 63-67℃ for 1 hour to finally obtain the surface modifier; In step S3, the mass ratio of modified calcium sulfate whiskers, modified rice husk charcoal, and recycled rubber is 8-12:15-20:

100. In step S3, the recycled rubber is selected from epoxidized natural rubber ENR-50.

2. A process for the preparation of reclaimed rubber based on modified calcium sulphate whiskers and rice husk char as claimed in claim 1, wherein, In step S1, the ultrasonic frequency is 40 kHz.

3. A process for the preparation of reclaimed rubber based on modified calcium sulphate whiskers and rice husk char as claimed in claim 1, wherein, In step S22, the flow rate of nitrogen is 50 mL / min.

4. The method for preparing reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal according to claim 1, characterized in that, The stirring speed in step S232 is 400-450 r / min.

5. The method for preparing reclaimed rubber based on modified calcium sulfate whiskers and rice husk charcoal according to claim 1, characterized in that, The dropping rate of hexamethylene diisocyanate in step S13 was 0.5 ml / min.

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