A pulverized fiber-reinforced epoxy resin-CuBDC composite material and a preparation method thereof

Abstract

The present invention provides a pulverized fiber-reinforced epoxy resin-CuBDC composite material and a preparation method thereof, belonging to the technical field of wear-resistant materials. The present invention uses CuBDC nanosheets and pulverized fibers as synergistic anti-wear fillers, which can effectively transfer from the composite material counterface surface to the bearing steel counterface surface during the friction and wear process of the material, and sinter to form a uniform and continuous transfer film under the friction chemical and friction physical reactions promoted by shear force and frictional heat. This kind of transfer film has good anti-wear effect and high load-carrying capacity, and can effectively reduce the wear of the composite material under high load conditions. The results of the examples show that the compressive strength of the pulverized fiber-reinforced epoxy resin-CuBDC composite material provided by the present invention is 157.33-214.42 MPa, the volumetric wear rate is (1.12-14.6)×10-6 mm3 / Nm, and the friction coefficient is 0.66-0.74.

Description

Technical Field

[0001] The present invention relates to the technical field of wear-resistant materials, and particularly relates to a crushed fiber-reinforced epoxy resin-CuBDC composite material and a preparation method thereof. Background Art

[0002] Epoxy resin (EP) is a thermosetting resin with excellent mechanical properties, good chemical stability and excellent adhesion properties. Relying on the above excellent properties, epoxy resin is widely used in the fields of coatings, fiber composites and friction materials. However, while the high cross-linking degree endows EP with excellent properties, it also leads to stress concentration in this series of materials and poor impact resistance. The relatively low toughness results in fatigue wear when the epoxy resin composite material is used as a tribological material in the field of sliding friction, which in turn leads to rapid wear and failure of the material components.

[0003] To solve the above problems, currently, the method of filling with anti-wear fillers is usually adopted to reduce the wear of epoxy resin. For example, the invention patent CN200610033638.0 discloses an epoxy resin friction-reducing and wear-resistant material filled with nano-inorganic particles, which uses nano-silica, nano-aluminum oxide, nano-silicon carbide, and nano-silicon nitride as reinforcing fillers. The specific wear rate of the obtained friction-reducing and wear-resistant material is 1.4-4.2 mm 3 / Nm, and its wear rate still needs to be further reduced. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a crushed fiber-reinforced epoxy resin-CuBDC composite material and a preparation method thereof. The crushed fiber-reinforced epoxy resin-CuBDC composite material provided by the present invention has a low volume wear rate and a low friction coefficient.

[0005] To achieve the above invention purpose, the present invention provides the following technical solutions:

[0006] The present invention provides a crushed fiber-reinforced epoxy resin-CuBDC composite material, which includes cured epoxy resin and CuBDC nanosheets and crushed fibers dispersed on the surface and inside of the cured epoxy resin.

[0007] Preferably, the diameter of the CuBDC nanosheets is 0.5-1.5 μm, and the length of the crushed fibers is 150 μm.

[0008] Preferably, the mass ratio of the cured epoxy resin to the CuBDC nanosheets is 100:3-20;

[0009] The mass ratio of the cured epoxy resin to the crushed fibers is 100:3-25.

[0010] Preferably, the comminuted fibers are one or more of chopped carbon fibers, chopped aramid fibers, and chopped glass fibers.

[0011] The present invention provides a method for preparing the above-mentioned comminuted fiber-reinforced epoxy resin-CuBDC composite material, comprising the following steps:

[0012] Mix epoxy resin, CuBDC nanosheets, comminuted fibers, and a curing agent, and perform thermal curing to obtain a comminuted fiber-reinforced epoxy resin-CuBDC composite material.

[0013] Preferably, the curing agent is one or more of diaminodiphenylmethane, diaminodiphenylsulfone, and m-phenylenediamine.

[0014] Preferably, the mass ratio of the epoxy resin to the curing agent is 100:10-20.

[0015] Preferably, the temperature of the thermal curing is 100-150 °C, and the time is 0.5-4 h.

[0016] Preferably, the method for preparing the CuBDC nanosheets comprises the following steps:

[0017] Mix a soluble copper salt, an inorganic strong base, and water to obtain a Cu(OH)2 suspension;

[0018] Mix a terephthalic acid solution with the Cu(OH)2 suspension and perform coordination assembly to obtain CuBDC nanosheets.

[0019] Preferably, the temperature of the coordination assembly is 20-80 °C, and the time is 20-40 min.

[0020] The present invention provides a comminuted fiber-reinforced epoxy resin-CuBDC composite material (abbreviated as EP / SCF / CuBDC composite material), comprising cured epoxy resin and CuBDC nanosheets and comminuted fibers dispersed on the surface and inside of the cured epoxy resin. The present invention uses CuBDC nanosheets and comminuted fibers as co-reinforcing fillers, wherein the CuBDC nanosheets are a kind of metal-organic framework material (MOFs) with a 2D sheet structure, the organic ligand thereof is terephthalic acid, and the coordinated metal is Cu 2+, CuBDC nanosheets have a unique lamellar structure and electron-deficient surface at the lattice scale, which causes the CuBDC filler to be effectively transferred from the composite material counterface surface to the bearing steel counterface surface during the sliding friction and wear process; at the same time, the relatively low thermal stability and good chemical activity also enable the transferred CuBDC to undergo tribochemical and tribophysical reactions under the action of shear force and frictional heat, further promoting the formation of a uniform and continuous transfer film. This kind of transfer film can effectively reduce the wear rate of the composite material under higher load conditions, achieving the anti-wear effect of the material. However, the transfer film promoted by CuBDC has problems such as a relatively long running-in time, unstable friction coefficient, and relatively high steady-state friction coefficient. In addition, the electron-deficient structure on the CuBDC surface also leads to the occurrence of reverse transfer of metal elements, which indicates the occurrence of metal counterface wear in the friction pair during the friction and wear process. In the present invention, by adding comminuted fibers, on the one hand, the comminuted fibers have good friction-reducing effects and can further reduce the friction coefficient during the sliding friction process of the friction pair; on the other hand, the load-bearing effect of the comminuted fibers can effectively reduce the contact between the epoxy resin-CuBDC filler phase and the metal counterface, while further reducing the wear of the resin matrix and alleviating the phenomenon of reverse transfer of metal elements. In addition, the frictional heat generated by the friction between the comminuted fibers and the bearing steel counterface can effectively promote the formation of the transfer film. The present invention uses CuBDC nanosheets and comminuted fibers as synergistic anti-wear fillers, which can be effectively transferred from the composite material counterface surface to the bearing steel counterface surface during the friction and wear process of the material, and sinter to form a uniform and continuous transfer film under the tribochemical and tribophysical reactions promoted by shear force and frictional heat. This kind of transfer film has good anti-wear properties and high load-bearing capacity, and can effectively reduce the wear of the composite material under higher load conditions. The results of the examples show that the compressive strength of the comminuted fiber-reinforced epoxy resin-CuBDC composite material provided by the present invention is 157.33 - 214.42 MPa, and the volumetric wear rate is (1.12 - 14.6)×10 -6 mm 3 / Nm, and the friction coefficient is 0.66 - 0.74. Description of the Drawings

[0021] Figure 1 is the scanning electron microscope image of the CuBDC nanosheets obtained in Example 1;

[0022] Figure 2 is the XRD pattern of the CuBDC nanosheets obtained in Example 1

[0023] Figure 3 is the air thermogravimetric curve of the CuBDC nanosheets obtained in Example 1;

[0024] Figure 4 is the scanning electron microscope image of the friction and wear surface of the EP / SCF / CuBDC composite material obtained in Example 1;

[0025] Figure 5 Friction coefficient - time curve of the EP / SCF / CuBDC composite material obtained in Example 1. Detailed implementation manners

[0026] The present invention provides a pulverized fiber - reinforced epoxy resin - CuBDC composite material, comprising a cured epoxy resin and CuBDC nanosheets and pulverized fibers dispersed on the surface and inside of the cured epoxy resin.

[0027] In the present invention, the diameter of the CuBDC nanosheets is preferably 0.5 - 1.5 μm, more preferably 1 - 1.2 μm; the length of the pulverized fibers is preferably 150 μm. In the present invention, the mass ratio of the cured epoxy resin to the CuBDC nanosheets is preferably 100:3 - 20, more preferably 100:5 - 18, and further preferably 100:10 - 15.

[0028] In the present invention, the mass ratio of the cured epoxy resin to the pulverized fibers is preferably 100:3 - 25, more preferably 100:5 - 20, and further preferably 100:10 - 15.

[0029] In the present invention, the pulverized fibers are preferably one or more of chopped carbon fibers, chopped aramid fibers, and chopped glass fibers. The present invention has no special requirements for the source of the pulverized fibers, and conventional commercially available pulverized fibers in the art can be used. As a specific embodiment of the present invention, the pulverized fibers are preferably CM150 - 3.0 / 200 - UN chopped carbon fibers from SGL Carbon Company in Germany, ATT - KF - 300F pulverized aramid fibers from Nanjing Tengyi New Materials Technology Co., Ltd., or E - MG300 chopped glass fibers from Nanjing Fiberglass Research and Design Institute.

[0030] In the present invention, the preparation method of the CuBDC nanosheets preferably comprises the following steps:

[0031] Mix a soluble copper salt, an inorganic strong base, and water to obtain a Cu(OH)2 suspension;

[0032] Mix a terephthalic acid solution with the Cu(OH)2 suspension and perform coordination assembly to obtain CuBDC nanosheets.

[0033] In the present invention, a soluble copper salt, an inorganic strong base, and water are mixed to obtain a Cu(OH)2 suspension. In the present invention, the soluble copper salt is preferably one or more of Cu(NO3)2·3H2O, Cu(AC)2, and Cu(Cl)2·2H2O; the inorganic strong base is preferably sodium hydroxide.

[0034] In the present invention, the mass ratio of the soluble copper salt, the inorganic strong base and water is preferably 5 to 25: 1 to 10: 50 to 250, more preferably 10 to 20: 5 to 8: 100 to 200. In the present invention, the mixing method is preferably ultrasonic mixing; the temperature during ultrasonic mixing is preferably -10 to 40 °C, more preferably 0 to 20 °C.

[0035] In the present invention, the terephthalic acid solution is mixed with the Cu(OH)2 suspension for coordination assembly to obtain CuBDC nanosheets. In the present invention, the solvent of the terephthalic acid solution is preferably N,N-dimethylformamide. In the present invention, the mass ratio of terephthalic acid to the soluble copper salt is preferably 5 to 25: 5 to 25.

[0036] In the present invention, the coordination assembly is preferably carried out under ultrasonic assistance. In the present invention, the temperature of the coordination assembly is preferably 20 to 80 °C, more preferably 60 to 80 °C.

[0037] After the coordination assembly, the present invention preferably performs post-treatment on the obtained coordination assembly reaction solution. The post-treatment preferably includes the following steps:

[0038] The coordination assembly reaction solution is subjected to solid-liquid separation. The solid is successively washed, dried and ground to obtain CuBDC nanosheets. In the present invention, the solid-liquid separation method is preferably centrifugation; the detergent for washing is preferably ethanol; the drying is preferably vacuum drying, the drying temperature is preferably 80 to 130 °C, and the time is preferably 3 h. The present invention preferably uses an agate mortar for the grinding.

[0039] The present invention provides a method for preparing the above-mentioned comminuted fiber-reinforced epoxy resin-CuBDC composite material, comprising the following steps:

[0040] Epoxy resin, CuBDC nanosheets, comminuted fibers and a curing agent are mixed and thermally cured to obtain a comminuted fiber-reinforced epoxy resin-CuBDC composite material.

[0041] In the present invention, the mixing method is preferably:

[0042] First, the epoxy resin and CuBDC nanosheets are successively subjected to first stirring and mixing and grinding to obtain an epoxy resin-CuBDC mixed solution;

[0043] Then, the comminuted fibers are secondarily stirred and mixed with the epoxy resin-CuBDC mixed solution to obtain a pre-dispersion;

[0044] The curing agent is thirdly stirred and mixed with the pre-dispersion.

[0045] In the present invention, before the first stirring and mixing, the epoxy resin is preferably dried to remove adsorbed water. In the present invention, the drying temperature is preferably 100 °C and the time is 24 h.

[0046] In the present invention, the rate of the first stirring and mixing is preferably 1000 rpm and the time is preferably 15 min. In the present invention, the grinding method is preferably grinding with a three-roll mill.

[0047] In the present invention, the rate of the second stirring is preferably 3000 rpm, the temperature is preferably 100 °C, and the time is preferably 15 min.

[0048] In the present invention, the rate of the third stirring is preferably 3000 rpm, the temperature is preferably 100 °C, and the time is preferably 3 min.

[0049] In the present invention, the curing agent is preferably added in a molten form. In the present invention, the curing agent is preferably one or more of diaminodiphenylmethane, diaminodiphenylsulfone, and m-phenylenediamine.

[0050] In the present invention, before the thermal curing, it is preferred to defoam the mixed solution of the obtained epoxy resin, CuBDC nanosheets, comminuted fibers, and curing agent. In the present invention, the defoaming method is preferably vacuum defoaming.

[0051] In the present invention, the temperature of the thermal curing is preferably 100 - 150 °C, more preferably 120 - 140 °C; the time is preferably 0.5 - 4 h. In the present invention, the thermal curing preferably includes a first thermal curing and a second thermal curing. The temperature of the first thermal curing is preferably 100 °C and the time is preferably 2 h. The temperature of the second thermal curing is preferably 150 °C and the time is preferably 2 h.

[0052] In the present invention, after the thermal curing, it is preferred to cut and polish the obtained composite material. The present invention has no special requirements for the specific operation methods of the cutting and polishing, and the cutting and polishing methods well-known to those skilled in the art can be used.

[0053] The following is a detailed description of the comminuted fiber-reinforced epoxy resin-CuBDC composite material and its preparation method provided by the present invention in combination with examples, but they cannot be construed as limiting the protection scope of the present invention.

[0054] Example 1

[0055] (1) Synthesis of CuBDC nanosheets

[0056] First, weigh 3.3 g of NaOH and 9.96 g of Cu(NO3)2·3H2O separately, and dissolve the above reagents in 83 mL and 75 mL of distilled water respectively by ultrasonic dissolution method. And the dissolved Cu 2+ solution was injected into the ultrasonic reactor, and the reaction temperature was controlled at 0 °C. Under ultrasonic assistance, the NaOH solution was added dropwise to the reaction system through the ultrasonic reactor to prepare a fresh Cu(OH)2 suspension. Subsequently, 6.64 g of terephthalic acid was weighed and dissolved in 200 mL of DMF solvent, and ultrasonic treatment was carried out for 5 min by the ultrasonic reactor to assist the dissolution of terephthalic acid. At the same time, the newly prepared Cu(OH)2 suspension was heated to 80 °C, the ultrasonic reactor was turned on, and the reaction temperature was controlled at 80 °C. Under ultrasonic-assisted synthesis conditions, the above terephthalic acid solution was added dropwise to the reaction system through a peristaltic pump at a feeding rate of 4 mL / min. After the addition was completed, the reaction temperature was maintained at 80 °C, and ultrasonic reaction was carried out for 20 min to obtain CuBDC nanosheets. Subsequently, CuBDC was separated by centrifugation and centrifugally washed with distilled water. The obtained product was dried in vacuo at 100 °C overnight, ground and pulverized with an agate mortar, and the obtained CuBDC powder was stored in a sealed bag filled with nitrogen for later use.

[0057] The scanning electron microscope image of the obtained CuBDC nanosheets is as Figure 1 shown. It can be seen from Figure 1 that the particle size of CuBDC is 0.5 - 1.5 μm, and it has a fine lamellar structure at the same time.

[0058] The XRD pattern of the obtained CuBDC nanosheets is as Figure 2 shown. It can be seen from Figure 2 by comparing with the 2D CuBDC standard card that CuBDC was successfully synthesized.

[0059] The air thermogravimetric curve of the obtained CuBDC nanosheets is as Figure 3 shown. It can be seen from Figure 3 that CuBDC has good thermal stability within the curing and forming processing temperature of epoxy resin (≤150 °C). At the same time, when the temperature is higher than 300 °C, CuBDC decomposes rapidly. This property indicates that the CuBDC particles transferred from the composite material interface are rapidly oxidized and decomposed under the action of frictional heat, and effectively promote the formation of the transfer film.

[0060] (2) Preparation of EP / SCF / CuBDC composites

[0061] First, weigh 9.14 g of CuBDC nanosheets and stir and mix them with 100 g of epoxy resin E-51. Subsequently, use a high-speed disperser to control the stirring rate at 1000 rpm and disperse for 15 min to preliminarily disperse the CuBDC nanosheets in the epoxy resin. Subsequently, transfer the above CuBDC-resin mixture to a three-roll grinder and continue to disperse to obtain a uniformly dispersed and ground CuBDC-resin mixture. Weigh 49.1 g of the above CuBDC-resin mixture, add 10.3 g of shredded carbon fibers (SCF) with a length of 150 μm to the system, use a high-speed stirrer, control the stirring temperature at 100 °C, control the stirring rate at 3000 rpm, and stir for 15 min to fully disperse the carbon fibers in the resin system. Finally, while maintaining the stirring temperature and stirring rate, add 12.6 g of the curing agent diaminodiphenylmethane (DDM) melted in an oven at 130 °C to the reaction system. Maintain the stirring rate and reaction temperature, disperse at high speed for 3 min, and vacuum degas the above prepolymer in a vacuum oven at 100 °C. Finally, pour the degassed resin prepolymer into a mold and cure the resin prepolymer through a curing process of 100 °C for 2 h and 150 °C for 2 h to obtain an EP / SCF / CuBDC composite material.

[0062] At room temperature, cut the EP / SCF / CuBDC composite material into polymer pins with dimensions of 13 mm × 4 mm × 4 mm, and polish the polymer pins with 1000-mesh sandpaper to fit the arc of the metal counterpart for later use.

[0063] Example 2

[0064] (1) Synthesis of CuBDC nanosheets

[0065] First, prepare CuBDC nanosheets by ultrasonic-assisted synthesis method. The steps are as follows: First, weigh 3.3 g of NaOH and 6.23 g of Cu(AC)2 respectively, and dissolve the above reagents in 83 mL and 50 mL of distilled water by ultrasonic dissolution method. And the dissolved Cu 2+The solution was injected into the ultrasonic reactor, and the reaction temperature was controlled at 0 °C. Under ultrasonic assistance in the ultrasonic reactor, NaOH solution was added dropwise to the reaction system to prepare a fresh Cu(OH)₂ suspension. Subsequently, 6.64 g of terephthalic acid was weighed and dissolved in 230 mL of DMF solvent, and ultrasonic treatment was carried out for 5 min by the ultrasonic reactor to assist the dissolution of terephthalic acid. At the same time, the newly prepared Cu(OH)₂ suspension was heated to 80 °C, the ultrasonic reactor was turned on, and the reaction temperature was controlled at 80 °C. Under ultrasonic-assisted synthesis conditions, the above terephthalic acid solution was added dropwise to the reaction system at a rate of 4 mL / min through a peristaltic pump. After the addition was completed, the reaction temperature was maintained at 80 °C, and ultrasonic reaction was carried out for 20 min to obtain CuBDC nanosheets. Subsequently, CuBDC was separated by centrifugation and washed by centrifugation with distilled water. The obtained product was dried in vacuo at 100 °C overnight, ground and pulverized using an agate mortar, and the obtained CuBDC powder was stored in a sealed bag filled with nitrogen for later use.

[0066] (2) Preparation of EP / SCF / CuBDC composite material

[0067] First, 4.32 g of CuBDC nanosheets was weighed and stirred and mixed with 100 g of epoxy resin E-44. Subsequently, a high-speed disperser was used to control the stirring rate at 1000 rpm and disperse for 15 min to preliminarily disperse the CuBDC nanosheets in the epoxy resin. Subsequently, the above CuBDC-resin mixture was transferred to a three-roll grinder and further dispersed to obtain a uniformly dispersed and ground CuBDC-resin mixture. 58.5 g of the above CuBDC-resin mixture was weighed, and 14.6 g of pulverized aramid fiber (SCF) with a length of 150 μm was added to the system. A high-speed stirrer was used to control the stirring temperature at 100 °C, the stirring rate at 3000 rpm, and the stirring time at 15 min to fully disperse the carbon fiber in the resin system. Finally, while maintaining the stirring temperature and stirring rate, 14.5 g of the curing agent diaminodiphenyl sulfone (DDS) melted in an oven at 130 °C was added to the reaction system. While maintaining the stirring rate and reaction temperature, high-speed dispersion was carried out for 3 min, and the above prepolymer was degassed in vacuo in a 100 °C vacuum oven. Finally, the degassed resin prepolymer was poured into a mold, and the resin prepolymer was cured by a curing process of 100 °C for 2 h and 150 °C for 2 h to obtain an EP / SCF / CuBDC composite material.

[0068] At room temperature, the EP / SCF / CuBDC composite material was cut into polymer pins of 13 mm × 4 mm × 4 mm and polished with 1000-mesh sandpaper to fit the arc of the metal counterpart for later use.

[0069] Example 3

[0070] (1) Synthesis of CuBDC Nanosheets

[0071] First, CuBDC nanosheets were prepared by an ultrasonic-assisted synthesis method as follows: First, 3.3 g of NaOH and 7.06 g of Cu(NO3)2·3H2O were weighed respectively, and the above reagents were dissolved in 80 mL and 100 mL of distilled water by ultrasonic dissolution method. And the dissolved Cu 2+ solution was injected into an ultrasonic reactor, the reaction temperature was controlled at 0 °C, and the NaOH solution was added dropwise to the reaction system under ultrasonic assistance through the ultrasonic reactor to prepare a fresh Cu(OH)2 suspension. Subsequently, 7.83 g of terephthalic acid was weighed into 150 mL of DMF solvent and ultrasonicated for 5 min by an ultrasonic reactor to assist the dissolution of terephthalic acid. At the same time, the newly prepared Cu(OH)2 suspension was heated to 80 °C, the ultrasonic reactor was turned on, the reaction temperature was controlled at 80 °C, and the above terephthalic acid solution was added dropwise to the reaction system at a feeding rate of 3 mL / min under ultrasonic-assisted synthesis conditions. After the dropping was completed, the reaction temperature was maintained at 80 °C and ultrasonically reacted for 20 min to obtain CuBDC nanosheets. Subsequently, CuBDC was separated by centrifugation and centrifugally washed with distilled water. The obtained product was dried in vacuo at 100 °C overnight, ground and pulverized with an agate mortar, and the obtained CuBDC powder was stored in a nitrogen-filled sealed bag for later use.

[0072] (2) Preparation of EP / SCF / CuBDC Composite

[0073] First, 12.7 g of CuBDC nanosheets were weighed and stirred and mixed with 100 g of epoxy resin E-54. Subsequently, a high-speed disperser was used to control the stirring rate at 1000 rpm and disperse for 15 min to preliminarily disperse the CuBDC nanosheets in the epoxy resin. Subsequently, the above CuBDC-resin mixture was transferred to a three-roll mill for further dispersion to obtain a uniformly dispersed and ground CuBDC-resin mixture. 40.6 g of the above CuBDC-resin mixture was weighed, and 10.3 g of comminuted glass fibers with a length of 150 μm was added to the system. A high-speed stirrer was used to control the stirring temperature at 100 °C, the stirring rate at 3000 rpm, and the stirring time at 15 min to fully disperse the carbon fibers in the resin system. Finally, while maintaining the stirring temperature and stirring rate, 12.6 g of the curing agent diaminodiphenylmethane (DDM) melted in an oven at 130 °C was added to the reaction system. While maintaining the stirring rate and reaction temperature, it was dispersed at high speed for 3 min, and the above prepolymer was degassed in vacuo in a 100 °C vacuum oven. Finally, the degassed resin prepolymer was poured into a mold, and the resin prepolymer was cured by a curing process of 100 °C for 2 h and 150 °C for 2 h to obtain the EP / SCF / CuBDC composite.

[0074] At room temperature, the EP / SCF / CuBDC composite material was cut into polymer pins with dimensions of 13 mm × 4 mm × 4 mm, and the polymer pins were polished with 1000-mesh sandpaper rings to fit the arc of the metal counterpart for later use.

[0075] Example 4

[0076] (1) Synthesis of CuBDC nanosheets

[0077] First, CuBDC nanosheets were prepared by an ultrasonic-assisted synthesis method. The steps were as follows: First, 5.1 g of NaOH and 9.96 g of Cu(NO3)2·3H2O were weighed respectively, and the above reagents were dissolved in 100 mL and 75 mL of distilled water by ultrasonic dissolution method. And the dissolved Cu 2+ solution was injected into the ultrasonic reactor. The reaction temperature was controlled at 20 °C. Under ultrasonic assistance, the NaOH solution was dropped into the reaction system through the ultrasonic reactor to prepare a fresh Cu(OH)2 suspension. Subsequently, 6.64 g of terephthalic acid was weighed in 150 mL of DMF solvent and ultrasonicated for 5 min by the ultrasonic reactor to assist the dissolution of terephthalic acid. At the same time, the newly prepared Cu(OH )2 suspension was heated to 20 °C, the ultrasonic reactor was turned on, and the reaction temperature was controlled at 20 °C. Under ultrasonic-assisted synthesis conditions, the above terephthalic acid solution was dropped into the reaction system at a feeding rate of 3 mL / min through a peristaltic pump. After the dropping was completed, the reaction temperature was maintained at 20 °C, and the ultrasonic reaction was carried out for 20 min to obtain CuBDC nanosheets. Subsequently, CuBDC was separated by centrifugation and centrifugally washed with distilled water. The obtained product was dried in vacuo at 100 °C overnight, ground and pulverized with an agate mortar, and the obtained CuBDC powder was stored in a sealed bag filled with nitrogen for later use.

[0078] (2) Preparation of EP / SCF / CuBDC composite material

[0079] First, weigh 9.14 g of CuBDC nanosheets and stir and mix them with 100 g of epoxy resin E-51. Subsequently, use a high-speed disperser to control the stirring rate at 1000 rpm and disperse for 15 min to preliminarily disperse the CuBDC nanosheets in the epoxy resin. Subsequently, transfer the above CuBDC-resin mixture to a three-roll grinder and continue to disperse to obtain a uniformly dispersed and ground CuBDC-resin mixture. Weigh 40.6 g of the above CuBDC-resin mixture, add 10.3 g of shredded carbon fiber (SCF) with a length of 150 μm to the system, use a high-speed stirrer, control the stirring temperature at 100 °C, control the stirring rate at 3000 rpm, and stir for 15 min to fully disperse the carbon fiber in the resin system. Finally, while maintaining the stirring temperature and stirring rate, add 12.6 g of the curing agent diaminodiphenylmethane (DDM) melted in an oven at 130 °C to the reaction system. Maintain the stirring rate and reaction temperature, disperse at high speed for 3 min, and vacuum degas the above prepolymer in a vacuum oven at 100 °C. Finally, pour the degassed resin prepolymer into a mold and cure the resin prepolymer through a curing process of 100 °C for 2 h and 150 °C for 2 h to obtain the EP / SCF / CuBDC composite material.

[0080] At room temperature, cut the EP / SCF / CuBDC composite material into polymer pins of 13 mm × 4 mm × 4 mm and polish the polymer pins with 1000-mesh sandpaper to fit the arc of the metal counterpart for later use.

[0081] Comparative Example 1

[0082] Preparation of EP / GF composite material

[0083] Weigh 45 g of epoxy resin E-51, use a high-speed stirrer, control the stirring temperature at 100 °C, control the stirring rate at 3000 rpm, add 10.3 g of shredded carbon fiber (SCF) with a length of 150 μm to the system, use a high-speed stirrer, control the stirring temperature at 100 °C, control the stirring rate at 3000 rpm, and stir for 15 min to fully disperse the carbon fiber in the resin system. Finally, while maintaining the stirring temperature and stirring rate, add 12.6 g of the curing agent diaminodiphenylmethane (DDM) melted in an oven at 130 °C to the reaction system. Maintain the stirring rate and reaction temperature, disperse at high speed for 3 min, and vacuum degas the above prepolymer in a vacuum oven at 100 °C. Finally, pour the degassed resin prepolymer into a mold and cure the resin prepolymer through a curing process of 100 °C for 2 h and 150 °C for 2 h to obtain the EP / GF composite material.

[0084] Comparative Example 2

[0085] (1) The synthesis of CuBDC nanosheets is the same as in Example 1.

[0086] (2) Preparation of EP / CuBDC composite material

[0087] First, weigh 9.14 g of CuBDC nanosheets and stir and mix them with 100 g of epoxy resin E-51. Subsequently, use a high-speed disperser to control the stirring rate at 1000 rpm and disperse for 15 min to preliminarily disperse the CuBDC nanosheets in the epoxy resin. Then, transfer the above CuBDC-resin mixture to a three-roll grinder and continue to disperse to obtain a uniformly dispersed and ground CuBDC-resin mixture. Weigh 49.1 g of the above CuBDC-resin mixture, use a high-speed mixer, control the stirring temperature at 100 °C, control the stirring rate at 3000 rpm, add 12.6 g of the curing agent diaminodiphenylmethane (DDM) melted in an oven at 130 °C to the reaction system, and stir for 3 min. And vacuum degas the above prepolymer in a vacuum oven at 100 °C. Finally, pour the degassed resin prepolymer into a mold and cure the resin prepolymer through a curing process of 100 °C for 2 h and 150 °C for 2 h to obtain the EP / CuBDC composite material.

[0088] Comparative Example 3

[0089] Preparation of EP cured resin

[0090] Weigh 45 g of epoxy resin E-51, use a high-speed mixer, control the stirring temperature at 100 °C, control the stirring rate at 3000 rpm, add 12.6 g of the curing agent diaminodiphenylmethane (DDM) melted in an oven at 130 °C to the reaction system, and stir for 3 min. And vacuum degas the above prepolymer in a vacuum oven at 100 °C. Finally, pour the degassed resin prepolymer into a mold and cure the resin prepolymer through a curing process of 100 °C for 2 h and 150 °C for 2 h to obtain the EP cured resin.

[0091] Performance testing

[0092] Test the compressive strength and tribological properties of the composite materials obtained in Examples 1-4 and Comparative Examples 1-3. Among them, the compressive strength of the materials is tested according to the national standard GB / T 1041-2008; the tribological properties are completed by a Jinan Yihua high-speed ring-block friction testing machine, and the test conditions are 4 MPa and 1 m / s. The obtained results are listed in Table 1.

[0093] Among them, the scanning electron microscope image of the friction and wear surface of the EP / SCF / CuBDC composite material obtained in Example 1 is as Figure 4 shown, and it can be seen from Figure 4 that CuBDC effectively reduces the fatigue wear phenomenon of the composite material, and at the same time, the addition of SCF effectively enhances the bearing capacity of the composite material.

[0094] The friction coefficient-time curve of the EP / SCF / CuBDC composite material obtained in Example 1 is as Figure 5 shown. From Figure 5 it can be seen that under the synergistic effect of SCF and CuBDC, the running-in time during the friction and wear process of the composite material is significantly shortened, the friction coefficient is significantly reduced, and the steady-state friction coefficient fluctuates less. This indicates that a transfer film with high load-bearing capacity is formed at the friction and wear interface under the synergistic effect of SCF and CuBDC.

[0095] Table 1 Properties of the composite materials obtained in the examples and comparative examples

[0096]

[0097] As can be seen from Table 1, the comminuted fiber-reinforced epoxy resin-CuBDC composite material provided by the present invention has a low volume wear rate and a low friction coefficient.

[0098] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A pulverized fiber-reinforced epoxy resin-CuBDC composite material, comprising cured epoxy resin and CuBDC nanosheets and pulverized fibers dispersed on the surface and inside of the cured epoxy resin; the organic ligand of the CuBDC nanosheets is terephthalic acid and the coordinated metal is Cu 2+ ; The diameter of the CuBDC nanosheets is 0.5 - 1.5 μm, and the length of the shredded fibers is 150 μm; The mass ratio of the cured epoxy resin to the CuBDC nanosheets is 100:3 - 20; The mass ratio of the cured epoxy resin to the shredded fibers is 100:3 - 25.

2. The comminuted fiber-reinforced epoxy-CuBDC composite material according to claim 1, wherein, The shredded fibers are one or more of chopped carbon fibers, chopped aramid fibers, and chopped glass fibers.

3. The method for preparing the shredded fiber-reinforced epoxy resin-CuBDC composite material according to claim 1 or 2, comprising the following steps: Mix the epoxy resin, CuBDC nanosheets, shredded fibers, and curing agent, and perform thermal curing to obtain the shredded fiber-reinforced epoxy resin-CuBDC composite material.

4. The preparation method according to claim 3, wherein, The curing agent is one or more of diaminodiphenylmethane, diaminodiphenylsulfone, and m-phenylenediamine.

5. The preparation method according to claim 3 or 4, characterized in that, The mass ratio of the epoxy resin to the curing agent is 100:10 - 20.

6. The preparation method according to claim 3, characterized in that, The temperature of the thermal curing is 100 - 150 °C, and the time is 0.5 - 4 h.

7. The preparation method according to claim 3, characterized in that, The method for preparing the CuBDC nanosheets comprises the following steps: Mix the soluble copper salt, inorganic strong base, and water to obtain a Cu(OH)2 suspension; Mix the terephthalic acid solution with the Cu(OH)2 suspension and perform coordination assembly to obtain the CuBDC nanosheets.

8. The preparation method according to claim 7, wherein The temperature of the coordination assembly is 20 - 80 °C, and the time is 20 - 40 min.

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