PLA-based flexible triboelectric material with core-shell structure for enhancing flame retardance and high temperature resistance and preparation method of PLA-based flexible triboelectric material

Abstract

The invention discloses a PLA-based flexible triboelectric material with a core-shell structure for enhancing flame retardance and high temperature resistance and a preparation method of the PLA-based flexible triboelectric material, and belongs to the technical field of triboelectric materials. The preparation method comprises the following technical steps: (1) adding carboxylated multi-walled carbon nanotubes into dichloromethane and N, N-dimethylformamide, and carrying out ultrasonic dispersion to obtain a dispersion liquid; (2) adding polylactic acid into the dispersion liquid, and carrying out magnetic stirring to obtain a core layer spinning solution; (3) adding calcium phytate and polylactic acid into dichloromethane and N, N-dimethylformamide, and carrying out magnetic stirring to obtain a shell spinning solution; (4) respectively filling the core spinning solution and the shell spinning solution into two push injectors, and carrying out coaxial electrostatic spinning to obtain a PLA-based nanofiber membrane; and (5) drying in a drying box to obtain the PLA-based flexible triboelectric material. According to the invention, a PLA / C-MWCNT core layer solution and a PLA / PA-Ca shell layer solution are subjected to coaxial electrostatic spinning to obtain the material with flame retardance, high temperature resistance and high triboelectric property.

Description

Technical Field

[0001] The invention relates to the technical field of triboelectric materials, and in particular to a PLA-based flexible triboelectric material with a core-shell structure and enhanced flame retardancy and high temperature resistance, and a preparation method thereof. Background Art

[0002] With the advent of the industrial age, advanced technologies such as the Internet of Things, big data, and artificial intelligence have promoted the rapid development of portable and wearable devices. However, traditional wearable devices rely on batteries that are prone to expansion and explosion in high-temperature environments, which severely limits the application of wearable devices in high-temperature places. Triboelectric nanogenerators (TENGs) based on the synergistic effect of triboelectric charging and electrostatic induction are an emerging energy harvesting technology that can convert widely distributed and tiny low-frequency energy in the environment into electrical energy, thereby realizing sensing functions. Due to the advantages of simple structure, wide material selection, and high energy conversion efficiency, wearable devices that can be used in high-temperature environments have been developed based on TENGs technology. Among them, green, environmentally friendly, and biodegradable triboelectric materials are becoming one of the key areas for the development of TENGs that meet the needs of high-temperature environments due to their advantages such as recyclability in the natural environment and harmlessness to the human body. However, most biodegradable triboelectric materials, including polyvinyl alcohol, cellulose, and polylactic acid (PLA), have unstable electrical output performance, flammability, and the risk of melting droplets at high temperatures. Therefore, the development of a flame-retardant, biodegradable, high-performance triboelectric material is very necessary for self-powered sensing in extreme environments such as high temperature and environmental sustainable development.

[0003] In recent years, PLA, a bio-based material with excellent biocompatibility, good biodegradability and outstanding processability, is often used as an excellent triboelectric material. However, PLA is limited by its low crystallinity and linear chain structure. It exhibits severe melting droplet phenomenon and poor thermal stability in high-temperature environments such as fires, and cannot be used in high-temperature environments. It is considered that the anti-melting droplet characteristics of PLA can be achieved by adding flame retardants such as calcium phytate (PA-Ca), hydroxyapatite, and chitosan, thereby improving its flame retardancy. The heat resistance of PLA can be improved by adding nucleating agents, blending, and cross-linking modification. Electrospinning technology can give PLA a rich porous micro-nano structure and a high specific surface area, thereby improving triboelectric properties. However, it is still challenging to improve the above three properties of PLA at the same time. Summary of the invention

[0004] In view of the above problems, the present invention provides a PLA-based flexible triboelectric material with enhanced flame retardancy and high temperature resistance through a core-shell structure and a preparation method thereof. By coaxially electrospinning a PLA / C-MWCNT core layer solution and a PLA / PA-Ca shell layer solution, a PLA-based flexible triboelectric material with high temperature resistance, flame retardancy and high triboelectric properties is prepared.

[0005] The present invention is achieved through the following technical solutions:

[0006] The method for preparing a PLA-based flexible triboelectric material with enhanced flame retardancy and high temperature resistance of a core-shell structure comprises the following steps:

[0007] (1) adding carboxylated multi-walled carbon nanotube (C-MWCNT) into dichloromethane (DCM) and dimethylformamide (DMF) solvents for ultrasonic dispersion to obtain a dispersion;

[0008] (2) adding polylactic acid (PLA) into the above dispersion and performing magnetic stirring to obtain a PLA / C-MWCNT core layer spinning solution;

[0009] (3) adding calcium phytate (PA-Ca) and PLA into DCM and DMF solvents and magnetically stirring to obtain a PLA / PA-Ca shell spinning solution;

[0010] (4) respectively loading the two core-shell spinning solutions of step (2) and step (3) into a pusher for coaxial electrospinning to obtain a PLA-based nanofiber membrane;

[0011] (5) Drying the PLA-based nanofiber membrane obtained in step (4) in a drying oven to obtain a PLA-based flexible triboelectric material.

[0012] As a further preferred embodiment, in step (1), 3.59 g of C-MWCNT is added per liter of solvent.

[0013] As a further preferred embodiment, in step (1), the volume ratio of DCM to DMF is 7:3.

[0014] As a further preferred embodiment, in step (1), the ultrasonication time is 1.5-2 h.

[0015] As a further preferred solution, in step (2), the amount of PLA added is 9% of the mass of the dispersion.

[0016] As a further preferred solution, in step (3), the amount of PLA added is 9% of the mass of the solvent; the PA-Ca accounts for 10-30wt% of the PLA. When the amount of PA-Ca added is 20wt% of the PLA, the performance is the best.

[0017] As a further preferred embodiment, in step (3), the volume ratio of DCM to DMF is 7:3.

[0018] As a further preferred solution, it is characterized in that in step (2) and step (3), the magnetic stirring time is 10-12 hours.

[0019] As a further preferred solution, in step (4), the coaxial needle model is 22G / 17G, and the injection speed of the core layer spinning solution is set to 1.5mL·h -1 The injection rate of the shell spinning solution was set to 2.0 mL·h -1 , the receiving distance was set to 20 cm, the spinning voltage was set to 20 kV, the ambient temperature was controlled at 25 °C, and the relative humidity was 40%.

[0020] As a further preferred solution, in step (5), the drying temperature is 60° C. and the drying time is 20-24 h.

[0021] The PLA-based flexible triboelectric material with a core-shell structure enhanced in flame retardancy and high temperature resistance prepared by the preparation method of the present invention has flame retardancy and high temperature resistance and can be applied in a high temperature fire environment.

[0022] Preparation principle of PLA-based flexible triboelectric material with enhanced flame retardancy and high temperature resistance of core-shell structure of the present invention:

[0023] The shell PA-Ca absorbs combustion free radicals at high temperature to form a dense phosphorus-containing carbon layer to play a flame retardant role. The core layer C-MWCNT acts as a nucleating agent and conductive filler to improve the crystallinity of PLA, and forms more conductive paths inside the material, promoting faster transmission and movement of triboelectric charges. Under the synergistic effect of the core-shell dual functional layer, the flame retardant and electrical output performance can be improved. The nanofiber material prepared by electrospinning technology has the characteristics of high specific surface area and high porosity, and is an ideal choice for loading conductive nanoparticles. The present invention constructs a PLA-based flexible degradable triboelectric material with a core (PLA / C-MWCNT) and shell (PLA / PA-Ca) structure to enhance flame retardancy and high temperature resistance through coaxial electrospinning technology. It mainly utilizes the inhibitory effect of PO· free radicals generated by the combustion and decomposition of PA-Ca and the physical barrier effect of the dense carbon layer to improve the flame retardancy. At the same time, electrospinning overcomes the brittleness of PLA and C-MWCNT, so that the film has sufficient flexibility. At the same time, under the action of proteinase K solution, PLA molecules can be degraded, so it is environmentally friendly and pollution-free.

[0024] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0025] 1. The core-shell structure of the PLA-based flexible triboelectric material prepared by the present invention enhances flame retardancy and high temperature resistance. The PO· free radicals generated during the combustion process will capture the HO· and H· combustion free radicals to interrupt the combustion. At the same time, the dense carbon layer after combustion will play a physical barrier role to block external heat and oxygen, so that the flammable PLA has excellent flame retardant properties. There is no droplet after ignition, and it will self-extinguish after leaving the fire.

[0026] 2. The PLA-based flexible triboelectric material with enhanced flame retardancy and high temperature resistance prepared by the present invention has good biodegradability, is environmentally friendly and pollution-free, because the ester bonds in the PLA molecules can be hydrolyzed under the action of proteinase K solution, and can be degraded in 7 days. Moreover, after significant deformation under stress bending, no fracture or permanent damage occurs, and multiple bending cycles can still be performed, showing excellent flexibility.

[0027] 3. The PLA-based flexible triboelectric material with core-shell structure enhanced flame retardancy and high temperature resistance prepared by the present invention has a highest open circuit voltage of 76.21 V at room temperature, and still has excellent triboelectric properties at high temperature (160°C, 52.19 V; after combustion, 9.81 V). BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of the preparation of the PLA-based flexible triboelectric material of the present invention.

[0029] Figure 2 This is a SEM image of the PLA-based flexible triboelectric material prepared in Example 4 of the present invention at a magnification of 2000.

[0030] Figure 3 This is the EDS element distribution diagram of the PLA-based flexible triboelectric material prepared in Example 4 of the present invention.

[0031] Figure 4 This is a combustion self-extinguishing diagram of the PLA-based flexible triboelectric material of the present invention under the flame of an alcohol lamp.

[0032] Figure 5 Graph showing the heat release rates of different PLA-based flexible triboelectric materials at different temperatures.

[0033] Figure 6 This is a degradation diagram of the PLA-based flexible triboelectric material of the present invention in a protease solution.

[0034] Figure 7 Voltage diagrams of different PLA-based flexible triboelectric materials at room temperature.

[0035] Figure 8 This is a voltage diagram of the PLA-based flexible triboelectric material prepared in Example 4 of the present invention at different high temperatures.

[0036] Fig. 9 This is a diagram of the triboelectric performance of the PLA-based flexible triboelectric material prepared in Example 4 of the present invention after burning for 20 seconds.

[0037] Table 1 shows the flame retardancy levels of different PLA-based flexible triboelectric materials of the present invention. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below by way of examples. These examples are only used to illustrate the present invention and do not limit the protection scope of the present invention.

[0039] Example 1

[0040] Preparation of PLA-based flexible triboelectric materials:

[0041] 9 wt% PLA powder was dissolved in a mixed solvent of DCM and DMF (7:3, v / v) and stirred for 12 h at room temperature with a magnetic stirrer to obtain a uniform spinning solution. Subsequently, the solution was injected into a 10 mL plastic syringe equipped with a 22G needle for electrospinning. The voltage of the electrospinning process was 20 kV and the propulsion speed was 1.5 mL h -1 , the collection speed is 130r·min -1 , the distance between the needle and the roller collector was 20 cm. The temperature and humidity were maintained at 25°C and 40%, respectively. Finally, after drying in an oven at 60°C for 24 hours, it was obtained and named Pure PLA.

[0042] Example 2

[0043] Preparation of PLA-based flexible triboelectric materials:

[0044] C-MWCNT accounting for 3wt% of PLA powder was ultrasonically dispersed in a mixed solvent of DCM and DMF (7:3, v / v). Then, 9wt% of PLA powder was dissolved in the mixed solvent, stirred continuously for 12h at room temperature with a magnetic stirrer, and then ultrasonically dispersed for 2h to obtain a uniform PLA / C-MWCNT solution. Subsequently, the PLA / C-MWCNT solution was injected into a 10mL plastic syringe equipped with a 22G needle for electrospinning. The voltage of the electrospinning process was 20kV and the propulsion speed was 1.5mL·h -1 , the collection speed is 130r·min -1The distance between the needle and the roller collector was 20 cm. The temperature and humidity were maintained at 25°C and 40%, respectively. Finally, after drying in a drying oven at 60°C for 24 hours, it was obtained and named P / C3.

[0045] Example 3

[0046] The method for preparing a PLA-based flexible triboelectric material with a core-shell structure and enhanced flame retardancy and high temperature resistance comprises the following steps:

[0047] (1) C-MWCNT accounting for 3 wt% of PLA powder (about 3.59 g of C-MWCNT per liter of mixed solvent) was added to a mixed solvent of DCM and DMF (7:3, v / v) and ultrasonically dispersed for 2 h to obtain a dispersion.

[0048] (2) 9 wt % of PLA powder was dissolved in the above dispersion and magnetically stirred for 12 h to obtain a uniform PLA / C-MWCNT core layer spinning solution.

[0049] (3) 9 wt % PLA powder was added to a mixed solvent of DCM and DMF (7:3, v / v), and then PA-Ca accounting for 10 wt % of PLA was added, and magnetic stirring was performed for 12 h to obtain a PLA / PA-Ca shell spinning solution.

[0050] (4) The two core-shell spinning solutions of step (2) and step (3) were respectively loaded into 10 mL plastic syringes, and coaxial electrospinning was performed using a 22G / 17G (core / shell) needle. The voltage of the electrospinning process was 20 kV, and the propulsion speed was 1.5 mL·h -1 (core) and 2.0 mL·h -1 (shell), collection speed is 130r·min -1 The distance between the needle and the roller collector was 20 cm. The temperature and humidity were maintained at 25 °C and 40%, respectively. Electrospinning was performed by injecting the solution into a plastic syringe with a coaxial needle model of 22G / 17G. The injection speed of the core layer spinning solution was set to 1.5 mL·h -1 The injection rate of the shell spinning solution was set to 2.0 mL·h -1 , the receiving distance was set to 20 cm, the spinning voltage was set to 20 kV, the ambient temperature was controlled at 25 °C, the relative humidity was 40%, and the PLA-based nanofiber membrane was obtained after electrospinning for 5 h;

[0051] (5) The PLA-based nanofiber membrane obtained in step (4) was dried in a drying oven at 60° C. for 24 h to obtain a PLA-based flexible triboelectric material, named P / C3P10.

[0052] Example 4

[0053] A method for preparing a PLA-based flexible triboelectric material with enhanced flame retardancy and high temperature resistance of a core-shell structure, comprising the following steps:

[0054] (1) C-MWCNT accounting for 3 wt% of PLA powder (about 3.59 g of C-MWCNT was added per liter of mixed solvent) was added to a mixed solvent of DCM and DMF (7:3, v / v) and ultrasonically dispersed for 2 h to obtain a dispersion.

[0055] (2) 9 wt % of PLA powder was dissolved in the above dispersion and magnetically stirred for 12 h to obtain a uniform PLA / C-MWCNT core layer spinning solution.

[0056] (3) 9 wt % of PLA powder was added to a mixed solvent of DCM and DMF (7:3, v / v), and then 20 wt % of PA-Ca was added to the PLA. The mixture was magnetically stirred for 12 h to obtain a PLA / PA-Ca shell spinning solution.

[0057] (4) The two core-shell spinning solutions of step (2) and step (3) were respectively loaded into 10 mL plastic syringes, and coaxial electrospinning was performed using a 22G / 17G (core / shell) needle. The voltage of the electrospinning process was 20 kV, and the propulsion speed was 1.5 mL·h -1 (core) and 2.0 mL·h -1 (shell), collection speed is 130r·min -1 The distance between the needle and the roller collector was 20 cm. The temperature and humidity were maintained at 25 °C and 40%, respectively. Electrospinning was performed by injecting the solution into a plastic syringe with a coaxial needle model of 22G / 17G. The injection speed of the core layer spinning solution was set to 1.5 mL·h -1 The injection rate of the shell spinning solution was set to 2.0 mL·h -1 , the receiving distance was set to 20 cm, the spinning voltage was set to 20 kV, the ambient temperature was controlled at 25 °C, the relative humidity was 40%, and the PLA-based nanofiber membrane was obtained after electrospinning for 5 h;

[0058] (5) The PLA-based nanofiber membrane obtained in step (4) was dried in a drying oven at 60° C. for 24 h to obtain a PLA-based flexible triboelectric material, named P / C3P20.

[0059] Example 5

[0060] The method for preparing a PLA-based flexible triboelectric material with a core-shell structure and enhanced flame retardancy and high temperature resistance comprises the following steps:

[0061] (1) C-MWCNT accounting for 3 wt% of PLA powder (about 3.59 g of C-MWCNT was added per liter of mixed solvent) was added to a mixed solvent of DCM and DMF (7:3, v / v) and ultrasonically dispersed for 2 h to obtain a dispersion.

[0062] (2) 9 wt % of PLA powder was dissolved in the above dispersion and magnetically stirred for 12 h to obtain a uniform PLA / C-MWCNT core layer spinning solution.

[0063] (3) 9 wt % of PLA powder was added to a mixed solvent of DCM and DMF (7:3, v / v), and then 30 wt % of PA-Ca was added to the PLA. The mixture was magnetically stirred for 12 h to obtain a PLA / PA-Ca shell spinning solution.

[0064] (4) The two core-shell spinning solutions of step (2) and step (3) were respectively loaded into 10 mL plastic syringes, and coaxial electrospinning was performed using a 22G / 17G (core / shell) needle. The voltage of the electrospinning process was 20 kV, and the propulsion speed was 1.5 mL·h -1 (core) and 2.0 mL·h -1 (shell), collection speed is 130r·min -1 The distance between the needle and the roller collector was 20 cm. The temperature and humidity were maintained at 25 °C and 40%, respectively. Electrospinning was performed by injecting the solution into a plastic syringe with a coaxial needle model of 22G / 17G. The injection speed of the core layer spinning solution was set to 1.5 mL·h -1 The injection rate of the shell spinning solution was set to 2.0 mL·h -1 , the receiving distance was set to 20 cm, the spinning voltage was set to 20 kV, the ambient temperature was controlled at 25 °C, the relative humidity was 40%, and the PLA-based nanofiber membrane was obtained after electrospinning for 5 h;

[0065] (5) The PLA-based nanofiber membrane obtained in step (4) was dried in a drying oven at 60° C. for 24 h to obtain a PLA-based flexible triboelectric material, named P / C3P30.

[0066] Material morphology characterization and analysis

[0067] (I) SEM analysis

[0068] The P / C3P20 flexible triboelectric material of Example 4 was characterized and analyzed using a scanning electron microscope (SEM). Figure 2 As shown, Figure 2 This is the SEM image of the P / C3P20 flexible triboelectric material of Example 4 at a magnification of 2000.

[0069] Depend on Figure 2 It can be seen that C-MWCNT and PA-Ca are uniformly dispersed on the PLA nanofibers, and the prepared P / C3P20 flexible triboelectric material is a nanofiber membrane.

[0070] The P / C3P20 flexible triboelectric material of Example 4 was characterized and analyzed by an energy dispersive spectrometer (EDS). Figure 3 As shown, Figure 3 This is the EDS image of the P / C3P20 flexible triboelectric material of Example 4.

[0071] Depend on Figure 3 It can be seen that C-MWCNT and PA-Ca are uniformly dispersed on the inner and outer layers of PLA nanofibers, and the appearance of Ca element indicates that PA-Ca is successfully introduced into PLA.

[0072] Material performance test analysis

[0073] (II) Flame retardant performance test

[0074] The materials obtained in Examples 1-5 were subjected to a flame retardant rating test (UL-94). The test results are as follows: Figure 4 And as shown in Table 1. Figure 4 The figure is a combustion self-extinguishing diagram of the PLA-based flexible triboelectric material of the present invention under flame. Table 1 shows the flame retardant grades of different PLA-based flexible triboelectric materials.

[0075] Table 1 Flame retardant grades of different PLA-based flexible triboelectric materials

[0076]

[0077] Depend on Figure 4 From ab, we can see that Pure PLA and P / C3 burn to the 125mm mark within 3 seconds after the first ignition and cannot be ignited again. Figure 4 c shows that P / C3P10 produces molten droplets in both ignitions, and the molten droplets ignite the absorbent cotton below. Figure 4 d shows that P / C3P20 has no molten droplets after the first ignition and extinguishes itself after leaving the fire source; it ignites near the fire source 8s after extinguishing and extinguishes itself after leaving the fire source. Figure 4 It can be seen that P / C3P30 has no droplets after the first ignition and extinguishes itself after leaving the fire source; it ignites near the fire source 3 seconds after extinguishing and extinguishes itself after leaving the fire source. The flame retardant grade is obtained as shown in Table 1. Pure PLA and P / C3 have the lowest flame retardant grade and no flame retardant grade. P / C3P10 reaches VTM-2 grade. P / C3P20 and P / C3P30 have the highest flame retardant grade, reaching VTM-0 grade.

[0078] The materials prepared in Examples 1-5 were subjected to flame retardancy tests. The test results are as follows: Figure 5 shown. Figure 5 This is a graph of heat release rates of PLA-based flexible triboelectric materials with different components at different temperatures.

[0079] Depend on Figure 5 It can be seen that the peak heat release rate (pHRR) of P / C3 flexible triboelectric material is only reduced by 5.07% compared with Pure PLA flexible triboelectric material. The peak heat release rate (pHRR) of P / C3P20 flexible triboelectric material is significantly reduced by 23.64% compared with PurePLA flexible triboelectric material. This shows that compared with P / C3 with only C-MWCNT added, the continued addition of PA-Ca can greatly reduce the heat release and fire hazard of polylactic acid (P / C3P20) combustion.

[0080] (III) Degradability test

[0081] The P / C3P20 material prepared in Example 4 was immersed in a 50°C proteinase K solution for degradation testing. The test results are as follows: Figure 6 shown. Figure 6 This is the degradation diagram of the P / C3P20 flexible triboelectric material of Example 4 in the protease solution.

[0082] Depend on Figure 6 It can be seen that the P / C3P20 flexible triboelectric material can be degraded in 7 days and has good biodegradability.

[0083] (IV) Electrical performance test at room temperature

[0084] The materials prepared in Examples 1-5 and FEP were cut into 2 cm × 2 cm squares and attached to acrylic plates with conductive adhesive to serve as positive and negative electrode materials. The positive and negative plates were respectively mounted on the TENGs electrical test bench to form TENGs in vertical contact separation mode. The test was conducted at a frequency of 2 Hz. The test results are shown in Figure 2. Figure 7 shown. Figure 7 In the figure, Pure PLA, P / C3, P / C3P10, P / C3P20, and P / C3P30 represent the materials prepared in Examples 1-5, respectively. Figure 7 The voltage diagram of the PLA-based flexible triboelectric materials of Examples 1-5 at room temperature.

[0085] Depend on Figure 7It can be seen that with the increase of C-MWCNT addition, the voltage of PLA-based flexible triboelectric materials increases; then with the increase of PA-Ca, the voltage of PLA-based flexible triboelectric materials first increases and then decreases, reaching the maximum at 20wt%. P / C3P20 flexible triboelectric material has the highest open circuit voltage (76.21V).

[0086] (V) Electrical performance test at different high temperatures

[0087] The P / C3P20 flexible triboelectric material and FEP prepared in Example 4 were cut into 2 cm × 2 cm squares and attached to a heat-resistant glass plate with conductive adhesive to be used as positive and negative electrode materials. The positive and negative plates were respectively installed on the TENGs electrical test bench to form a vertical-contact separation mode TENGs. The temperature of the heating plate was controlled by a temperature control box to control the temperature of the positive plate. The test was carried out at a frequency of 2 Hz. The test results are shown in Figure 2. Figure 8 shown. Figure 8 This is a voltage diagram of the P / C3P20 flexible triboelectric material of Example 4 at different temperatures.

[0088] Depend on Figure 8 It can be seen that as the temperature increases, the voltage of the P / C3P20 flexible triboelectric material gradually decreases due to the thermal ion emission effect. Then, the voltage remains basically unchanged during the cyclic heating, showing excellent cycle performance under high temperature conditions.

[0089] (VI) Electrical performance test after combustion

[0090] The P / C3P20 flexible triboelectric material and FEP prepared in Example 4 were cut into 2cm×2cm squares, and the P / C3P20 flexible triboelectric material prepared in Example 4 was burned for 20s. The burned P / C3P20 flexible triboelectric material and FEP were then attached to an acrylic plate with conductive adhesive and used as positive and negative electrode materials. The positive and negative plates were respectively mounted on the TENGs electrical test bench to form TENGs in vertical-contact separation mode. The test was carried out at a frequency of 2Hz, and the test results are shown as follows: Fig. 9 shown. Fig. 9 The actual image, voltage and charge diagram of the P / C3P20 flexible triboelectric material of Example 4 after burning for 20 seconds.

[0091] Depend on Fig. 9 It can be seen that even after combustion, the P / C3P20 flexible triboelectric material can still output an open circuit voltage of 9.81 V and a transfer charge of 3.22 nC, showing excellent triboelectric performance after fire attack.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a PLA-based flexible triboelectric material with enhanced flame retardancy and high temperature resistance of a core-shell structure, characterized in that: The following steps are involved: (1) adding carboxylated multi-walled carbon nanotubes into dichloromethane and N-N-dimethylformamide solvents and dispersing by ultrasonication to obtain a dispersion; (2) adding polylactic acid to the above dispersion and subjecting it to magnetic stirring to obtain a polylactic acid / carboxylated multi-walled carbon nanotube core layer spinning solution; (3) adding calcium phytate and polylactic acid into dichloromethane and NN dimethylformamide solvents and magnetically stirring to obtain a polylactic acid / calcium phytate shell spinning solution; (4) respectively loading the two core-shell spinning solutions of step (2) and step (3) into a pusher for coaxial electrospinning to obtain a PLA-based nanofiber membrane; (5) Drying the PLA-based nanofiber membrane obtained in step (4) in a drying oven to obtain a PLA-based flexible triboelectric material.

2. The method for preparing the PLA-based flexible triboelectric material with enhanced flame retardancy and high temperature resistance of the core-shell structure according to claim 1, characterized in that: In step (1), 3.0-4.0 g of carboxylated multi-walled carbon nanotubes are added to each liter of solvent.

3. The method for preparing the PLA-based flexible triboelectric material with enhanced flame retardancy and high temperature resistance of the core-shell structure according to claim 1, characterized in that: In step (1), the volume ratio of dichloromethane to N-dimethylformamide is 7:3; and the ultrasonic dispersion time is 1.5-2h.

4. The method for preparing the PLA-based flexible triboelectric material with enhanced flame retardancy and high temperature resistance of the core-shell structure according to claim 1, characterized in that: In step (2), the amount of polylactic acid added is 9% of the mass of the dispersion.

5. The method for preparing the PLA-based flexible triboelectric material with enhanced flame retardancy and high temperature resistance of the core-shell structure according to claim 1, characterized in that: In step (3), the amount of polylactic acid added is 9% of the mass of the solvent; and the calcium phytate accounts for 10-30wt% of the polylactic acid.

6. The method for preparing the PLA-based flexible triboelectric material with enhanced flame retardancy and high temperature resistance of the core-shell structure according to claim 1, characterized in that: In step (3), the volume ratio of dichloromethane to N-dimethylformamide is 7:

3.

7. The method for preparing a PLA-based flexible triboelectric material with enhanced flame retardancy and high temperature resistance according to claim 1, characterized in that: In step (2) and step (3), the magnetic stirring time is 10-12 hours.

8. The method for preparing the PLA-based flexible triboelectric material with enhanced flame retardancy and high temperature resistance of the core-shell structure according to claim 1, characterized in that: In step (4), the coaxial needle model is 22G / 17G, and the injection speed of the core layer spinning solution is set to 1.5mL·h -1 The injection rate of the shell spinning solution was set to 2.0 mL·h -1 , the receiving distance was set to 20 cm, the spinning voltage was set to 20 kV, the ambient temperature was controlled at 25 °C, the relative humidity was 40%, and the spinning time was 5 h.

9. The method for preparing a PLA-based flexible triboelectric material with enhanced flame retardancy and high temperature resistance according to claim 1, characterized in that: In step (5), the drying temperature is 60° C. and the drying time is 20-24 hours.

10. The PLA-based flexible triboelectric material with flame retardancy and high temperature resistance enhanced by the core-shell structure and the preparation method thereof as claimed in any one of claims 1 to 9, to obtain a PLA-based flexible triboelectric material with flame retardancy and high temperature resistance.

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