Loofah sponge modified epoxy resin based three-dimensional lubricating composite material and preparation method thereof

Abstract

The invention discloses a loofah sponge modified epoxy resin based three-dimensional lubricating composite material and a preparation method thereof. The composite material comprises the following raw materials in percentage by weight: 90-99% of EP and 1-10% of a three-dimensional fiber reinforcement, wherein the three-dimensional fiber reinforcement is a three-dimensional reinforcement surface loaded with LF prepared by mixing and weaving MOF and PW through a knitting method. The loofah sponge is used as a three-dimensional biomass material and has a three-dimensional structure, the special three-dimensional structure of the loofah sponge can store and release a lubricating medium, and the vein of the loofah sponge can be used as a release passage of a lubricant; according to the modified loofah sponge epoxy resin-based three-dimensional lubricating composite material, the interface bonding of loofah sponge and epoxy resin can be improved, lubricating components are slowly released through a three-dimensional structure, the friction coefficient and the volume wear rate of the composite material are reduced by 79.4% and 61.5% respectively, and meanwhile, the tribological performance of the modified loofah sponge composite material in an oil environment is researched; and the friction coefficient and the wear rate are reduced by 53.3% and 97.3% respectively.

Description

Technical Field

[0001] The present invention belongs to the technical field of the preparation of polymer composites, and particularly relates to a loofah-modified epoxy resin-based three-dimensional lubricating composite material and a preparation method thereof. Background Art

[0002] Epoxy resin (EP), as a common thermosetting resin, has a series of excellent properties, such as high tensile strength, high adhesion, wear resistance, corrosion resistance, etc. It has been widely studied and applied in the fields of mechanical equipment manufacturing and industrial production. However, the three-dimensional cross-linked network structure of EP after curing leads to an increase in its brittleness and a decrease in its fatigue resistance, and its application as a tribological sliding element is limited. Therefore, a lubricating medium is introduced into the epoxy resin to improve its tribological properties. Since the three-dimensional cross-linked network of the epoxy resin is relatively tight and it is difficult to store the lubricating medium, other materials need to be introduced as the medium for storing the lubricant, so as to improve the tribological properties of the material.

[0003] Loofah (LF) is a natural biomass material with a unique three-dimensional network structure, ultra-high porosity and light weight characteristics. In theory, it can be used as an ideal carrier for lubricants. Metal-organic framework materials (MOF) are considered to be cutting-edge porous materials after zeolites and carbon nanotubes, and have been widely used in the fields of catalysts, energy storage and adsorption. MOF contains metal ions and organic ligands, and can form a three-dimensional (3D) extended structure through corresponding coordination chemical reactions. Due to the unique properties of MOF, different MOFs have been used to modify materials to obtain high performance. The introduction of MOF can enhance the binding between LF and EP. Paraffin wax (PW) has shown its potential application in reducing the friction coefficient. Adding solid paraffin wax provides a lubricant storage space and transportation path for the three-dimensional structure of LF. During the friction process, PW undergoes a phase change under the influence of frictional heat and is slowly released to the friction interface via LF to achieve continuous lubrication. Summary of the Invention

[0004] In order to overcome the above deficiencies, the present invention provides a loofah-modified epoxy resin-based lubricating composite material and a preparation method thereof.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A loofah-modified epoxy resin-based three-dimensional lubricating composite material, comprising raw materials in the following weight percentages: 90% - 99% of EP and 1% - 10% of a three-dimensional fiber reinforcing body, wherein the three-dimensional fiber reinforcing body is a three-dimensional reinforcing body prepared by mixing and knitting MOF and PW and having LF loaded on its surface.

[0006] A preparation method of a loofah-modified epoxy resin-based three-dimensional lubricating composite material, the specific steps are as follows: Step 1. Under magnetic stirring, NiCl2 · 6H 2 O and H 2 BDC was dissolved in a mixed solvent of DMF, ethanol and deionized water. This solution and the dried LF were transferred to a high-pressure reactor and heated. After completion, it was cooled to room temperature and washed with ethanol and dichloromethane respectively. After drying, LF / Ni-MOF was obtained. Step 2: LF / Ni-MOF and solid paraffin were put into a beaker according to a mass ratio of 1:15 and placed in an oven to be completely melted. After cooling and solidifying at room temperature, LF / Ni-MOF / PW was obtained. Step 3: LF / Ni-MOF / PW and the treated EP were put into a clean mold and cured at room temperature for 20 - 28 h, then placed in an oven at 70 - 90 °C for 5 - 7 h for further curing. After the curing was completed, it was left standing at room temperature for 20 - 28 h, and the EP / LF / Ni-MOF / PW composite material was obtained.

[0007] Further optimization: The LF in Step 1 was the pretreated raw material, and the pretreatment method was: LF was cut into blocks of 30 mm × 30 mm, alternately washed with absolute ethanol and deionized water 2 - 4 times, with each washing time being 3 - 7 min. The washed LF was dried in an oven at 55 - 65 °C for 10 - 14 h.

[0008] Further optimization: The heating temperature in the high-pressure reactor oven in Step 1 was 130 - 150 °C, and the heating time was 8 - 12 h.

[0009] Further optimization: The treatment method of EP in Step 3 was: EP was put into a beaker, stirred with acetone for 4 - 6 min for dilution, then cured with a curing agent, and continuously stirred for 20 - 40 min. Then the beaker was placed in an ultrasonic machine and ultrasonicated for 8 - 12 min to eliminate bubbles.

[0010] Further optimization: The mold in Step 3 was a cube mold with a length of 30 mm, a width of 30 mm, and a height of 10 mm.

[0011] The beneficial effects of the present invention are as follows: (1) In the present invention, loofah sponge, as a three-dimensional biomass material, has its own three-dimensional structure, ultra-high porosity and light weight characteristics. Its special three-dimensional structure can store and release lubricating media, and its veins can serve as release channels for lubricants. (2) The modified loofah sponge epoxy resin-based three-dimensional lubricating composite material in the present invention can enhance the interfacial bonding between loofah sponge and epoxy resin, slowly release lubricating components through the three-dimensional structure, effectively reduce the friction coefficient, and play an effective role in reducing friction and wear. (3) The preparation process of the present invention is simple. The composite material can be prepared by the room-temperature mixing and casting method. Through actual tests, it is known that the tribological properties of the composite material of the present invention, compared with pure EP, the friction coefficient and the volume wear rate are reduced by 79.4% and 61.5% respectively. At the same time, the tribological properties of the modified loofah composite material in an oil environment are explored, and its friction coefficient and wear rate are reduced by 53.3% and 97.3% respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a graph showing the change of the friction coefficient of the epoxy resin composite material with time in a dry friction environment; Figure 2 It is a comparison chart of the average wear amount of the epoxy resin composite material in a dry friction environment; Figure 3 It is a graph showing the change of the friction coefficient of the epoxy resin composite material with time in an oil lubrication environment; Figure 4 It is a comparison chart of the average wear amount of the epoxy resin composite material in an oil lubrication environment; Figure 5 It is an SEM photo of LF at 1 mm; Figure 6 It is an SEM photo of LF / Ni-MOF at 1 mm; Figure 7 It is an SEM photo of LF / Ni-MOF / PW at 1 mm; Figure 8 It is an SEM photo of LF at 100 μm; Figure 9 It is an SEM photo of LF / Ni-MOF at 100 μm; Figure 10 It is an SEM photo of LF / Ni-MOF / PW at 100 μm. DETAILED DESCRIPTION OF THE INVENTION

[0013] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention will be described in detail below with reference to specific embodiments. The following embodiments are implemented on the premise of the technical solution of the present invention, and the detailed implementation manners and specific operation processes are given. However, the present invention can also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the following embodiments.

[0014] Example 1 Step 1: Cut the loofah into loofah blocks of 30 mm × 30 mm. Wash the loofah blocks with absolute ethanol for 5 minutes, and then wash them with deionized water for 5 minutes. Alternate like this 3 times. Dry the washed loofah in an oven at 60 °C for 12 hours, and then dry it for standby; Under magnetic stirring, 1 mmol of NiCl 2 · 6H 2 O and 1 mmol of H 2 BDC were dissolved in a mixture of 32 mL of DMF, 2 mL of ethanol, and 2 mL of deionized water. Subsequently, this solution and the above-mentioned loofah sponge were transferred to a high-pressure reactor. The high-pressure reactor was heated in an oven at 140 °C for 10 h. After it cooled to room temperature, it was washed three times with ethanol and once with dichloromethane, and then dried at 40 °C for 12 h to obtain LF / MOF.

[0015] Step 2: Place the loofah sponge / MOF in a beaker. Put LF / Ni-MOF and solid paraffin into the beaker according to a mass ratio of 1:15. Melt the solid paraffin in an oven at 80 °C and then let it solidify at room temperature to obtain the LF / Ni-MOF / PW material.

[0016] Step 3: Weigh 20 g of E-51 epoxy resin into a beaker. Then measure 4 mL of acetone as a diluent and add it to the beaker and stir for 5 min. Then add 5 g of 593 curing agent and continue to stir for 30 min. After stirring, place the beaker in an ultrasonic machine and ultrasonicate for 10 min to remove bubbles; Scrub the mold with ethanol cotton, wipe it clean, and then wipe it with dry cotton until clean. Put LF / Ni-MOF / PW and the above-mentioned treated EP into a clean mold, let it cure at room temperature for 24 h, and then place it in an oven at 80 °C for 6 h to continue curing. After curing, let it stand at room temperature for 24 h to obtain the EP / LF / Ni-MOF / PW composite material.

[0017] Comparative Example 1 Weigh 20 g of E-51 epoxy resin into a beaker. Then measure 4 mL of acetone as a diluent and add it to the beaker. Add 5 g of 593 curing agent to the beaker in Step 3 and stir for 30 min. Place the beaker in an ultrasonic machine and ultrasonicate for 10 min to remove bubbles. Scrub the mold with ethanol cotton, wipe it clean, and then wipe it with dry cotton until clean. Pour the liquid in the beaker in Step 5 into the wiped clean mold and first let it cure at room temperature for 24 h to obtain the pure EP material.

[0018] Comparative Example 2 Cut the loofah sponge into loofah sponge blocks of 30 mm × 30 mm. Wash the loofah sponge blocks with absolute ethanol for 5 minutes and then with deionized water for 5 minutes, and alternate like this 3 times. Dry the washed loofah sponge in an oven at 60 °C for 12 h and then dry it for standby.

[0019] Weigh 20 g of E-51 epoxy resin into a beaker, then measure 4 ml of acetone as a diluent and add it to the beaker, and stir for 30 min. After stirring, place the beaker in an ultrasonic machine and ultrasonicate for 10 min to remove bubbles. Scrub the mold with ethanol cotton, wipe it clean, and then wipe it with dry cotton until it is clean. Place the dried loofah sponge block into the mold. Pour the liquid in the beaker from Step 5 into the wiped mold, and first let it cure at room temperature for 24 h to obtain the EP / LF material.

[0020] Comparative Example 3 Cut the loofah sponge into loofah sponge blocks of 30 mm × 30 mm. Wash the loofah sponge blocks with absolute ethanol for 5 minutes, then wash with deionized water for 5 minutes, and alternate like this 3 times. Wash the cleaned loofah sponge, dry it in an oven at 60 °C for 12 h, and then dry it for standby. Under magnetic stirring, dissolve 1 mmol NiCl 2 · 6H 2 O and 1 mmol H 2 BDC in a mixture of 32 mL of DMF, 2 mL of ethanol and 2 mL of deionized water. Subsequently, transfer this solution and the above-mentioned loofah sponge to a high-pressure reaction kettle. Heat the high-pressure reaction kettle in an oven at 140 °C for 10 h. After it cools to room temperature, wash it three times with ethanol and once with dichloromethane, and dry it at 40 °C for 12 h to obtain the LF / MOF material.

[0021] Weigh 20 g of E-51 epoxy resin into a beaker, then measure 4 ml of acetone as a diluent and add it to the beaker. Add 5 g of 593 curing agent to the beaker in Step 3 and stir for 30 min. After stirring, place the beaker in an ultrasonic machine and ultrasonicate for 10 min to remove bubbles. Scrub the mold with ethanol cotton, wipe it clean, and then wipe it with dry cotton until it is clean. Place the dried loofah sponge / MOF into the mold. Pour the liquid in the beaker from Step 5 into the wiped mold, and first let it cure at room temperature for 24 h to obtain the EP / LF / Ni-MOF material.

[0022] Test the EP composite materials prepared in Example 1 and Comparative Examples 1 - 3 under dry friction conditions, as shown in Figure 1 、 2 and Table 1. Test the friction performance of the EP composite materials prepared in Comparative Examples 1 - 3 under an oil environment, as shown in Figure 3 、 4 and Table 2.

[0023] Product Performance Test Friction performance: According to the standard test method of GB / T 3960 - 1983, the friction and wear performance of the composite material was evaluated on an MM-2HL ring-block testing machine. The test load was 40 N, the test rotation speed was 100 r / min, the test time was 30 min, and the counter ring was a steel ring with a diameter of 40 mm. (The test under the oil lubrication environment was achieved by dropping 2 drops of liquid paraffin on the contact surface between the steel ring and the composite material every 3 minutes). Table 1 Friction performance test of EP composite materials prepared in Example 1 and Comparative Examples 1 - 3 Table 2 Friction performance test of EP composite materials prepared in Comparative Examples 1 - 3 Analyzing Table 1 and Table 2, compared with Comparative Example 1, the tribological performance of the composite material in the dry friction environment of Example 1 and Comparative Examples 2 - 3 was significantly improved compared with Comparative Example 1. The tribological performance of Example 1 and Comparative Example 2 in the oil lubrication friction environment was better than that of Comparative Example 1.

[0024] Figure 1 It is a curve graph of the change of the friction coefficient of the epoxy resin composite material with time under dry friction conditions, Figure 2 It is a bar graph of the average friction coefficient and wear amount of the epoxy resin composite material under dry friction conditions. Compared with the pure EP material, the friction coefficient and wear amount of the EP / LF / Ni-MOF composite material decreased. This is because Ni-MOF can improve the tribological performance of the composite material, and the three-dimensional structure of loofah sponge can store solid paraffin, and the solid paraffin undergoes a phase change and is released to the friction interface during the friction process. Therefore, the friction coefficient and wear amount of EP / LF / Ni-MOF / PW are the lowest.

[0025] Figure 3 It is a curve graph of the change of the friction coefficient of the epoxy resin composite material with time under oil lubrication conditions, Figure 4 It is a bar graph of the average friction coefficient and wear amount of the epoxy resin composite material under oil lubrication conditions. In the oil dripping environment, the friction performance of EP / LF is better than that of pure EP. After adding Ni-MOF, since Ni - MOF can fill the pores and defects during the friction process, promote the formation of the lubricating film, and reduce the generation of wear particles, the friction performance of the EP / LF / Ni-MOF composite material is more excellent.

[0026] Figure 5 It is the SEM photo of LF at 1 mm; Figure 6 It is the SEM photo of LF / Ni-MOF at 1 mm; Figure 7 It is the SEM photo of LF / Ni-MOF / PW at 1 mm; Figure 8SEM image of LF at 100um; Figure 9 SEM image of LF / Ni-MOF at 100um; Figure 10 SEM image of LF / Ni-MOF / PW at 100um. Comparison Figure 5 、 Figure 6 、 Figure 7 、 Figure 8 、 Figure 9 、 Figure 10 It can be seen that after treatment on the surface of loofah sponge, Ni-MOF and PW will be evenly loaded on the surface of loofah sponge.

[0027] The above shows and describes the main features, usage methods, basic principles and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will also have various changes and improvements according to actual situations, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A loofah-modified epoxy resin-based three-dimensional lubricating composite material, characterized in that: The invention comprises the following raw materials in weight percentage: EP 90% to 99% and three-dimensional fiber reinforcement 1% to 10%, wherein the three-dimensional fiber reinforcement is a three-dimensional reinforcement surface loaded with LF prepared by mixing MOF and PW through knitting.

2. The method for preparing a loofah-modified epoxy resin-based three-dimensional lubricating composite material as claimed in claim 1, wherein: The specific steps are as follows: Step 1: Under magnetic stirring, NiCl2·6H2O and H2BDC were dissolved in a mixed solvent of DMF, ethanol and deionized water, and the solution and the dried LF were transferred to a high-pressure reactor for heating. After heating, the mixture was cooled to room temperature, washed with ethanol and dichloromethane, respectively, and dried to obtain LF / Ni-MOF; Step 2: LF / Ni-MOF and solid paraffin were placed in a beaker at a mass ratio of 1:15, and placed in an oven to completely melt, and then cooled and solidified at room temperature to obtain LF / Ni-MOF / PW; Step 3: Place LF / Ni-MOF / PW and the treated EP into a clean mold, place them at room temperature for 20-28 hours to cure, and then place them in a 70-90°C oven for 5-7 hours to continue curing. After curing, place them at room temperature for 20-28 hours to obtain an EP / LF / Ni-MOF / PW composite material.

3. The preparation method of loofah-modified epoxy resin-based three-dimensional lubricating composite material as claimed in claim 2, characterized in that, The LF in step 1 is a pretreated raw material, and the pretreatment method is: cut the LF into 30 mm × 30 mm blocks, wash it 2-4 times with anhydrous ethanol and deionized water alternately, each washing time is 3-7 minutes, and dry the washed LF in an oven at 55-65° C. for 10-14 hours.

4. The preparation method of loofah-modified epoxy resin-based three-dimensional lubricating composite material as claimed in claim 2, characterized in that, The heating temperature in the high pressure reaction kettle oven in the step 1 is 130-150° C., and the heating time is 8-12 hours.

5. The preparation method of loofah-modified epoxy resin-based three-dimensional lubricating composite material as claimed in claim 2, characterized in that, The treatment method of EP in step 3 is: put EP into a beaker, add acetone and stir for 4-6 minutes to dilute, then add curing agent to cure, continue stirring for 20-40 minutes, and then put the beaker into an ultrasonic machine for 8-12 minutes to eliminate bubbles.

6. The preparation method of loofah-modified epoxy resin-based three-dimensional lubricating composite material as claimed in claim 2, characterized in that, The mold in step 3 is a cube mold with a length of 30 mm, a width of 30 mm, and a height of 10 mm.

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