Natural rubber composite material based on piezoelectric material graphene modification and preparation method thereof

Abstract

The invention discloses a graphene modified natural rubber composite material based on a piezoelectric material and a preparation method thereof, and relates to the technical field of piezoelectric material preparation, and the preparation method comprises the following steps: adding piezoelectric particles PZT into a sodium hydroxide solution for hydroxylation treatment; adding the PZT particles subjected to hydroxylation treatment into graphene oxide GO slurry, stirring to react, directionally freezing and freeze-drying to obtain a PZT-GO piezoelectric-conductive filler three-dimensional network structure; taking a rubber additive, performing ball milling to obtain a rubber additive dispersion liquid, adding the rubber additive dispersion liquid into the natural latex emulsion, stirring, then adding the graphene oxide dispersion liquid, adding the mixed dispersing agent into the three-dimensional network structure of the PZT-GO piezoelectric-conductive filler, drying, and performing hot-pressing vulcanization to obtain PZT-GO piezoelectric-conductive rubber; and carrying out polarization treatment in silicone oil, and carrying out ultrasonic cleaning to obtain the polarized PZT-GO piezoelectric-conductive rubber. The flexible piezoelectric material has good flexibility, and has excellent piezoelectric property and conductivity while meeting the processing requirements of flexible materials.

Description

Technical Field

[0001] The present invention relates to the technical field of piezoelectric material preparation, and particularly to a natural rubber composite modified by graphene based on piezoelectric materials and a preparation method thereof. Background Art

[0002] In recent years, due to their unique piezoelectric effect, piezoelectric materials have shown great application potential in fields such as sensors, transducers, and intelligent devices. Especially in new devices that pursue lightweight, flexibility, and intelligence, such as smart wearables, bionic prosthetics, and flexible electronic skins, the application of piezoelectric materials has received extensive attention. However, traditional piezoelectric materials often have defects such as poor conductivity, insufficient flexibility, and complex preparation processes, making it difficult to meet the high requirements for material properties in new devices.

[0003] To overcome these problems, researchers have begun to explore the combination of piezoelectric materials with new nanomaterials such as graphene, in order to obtain new composite materials with both piezoelectric effects and excellent electrical conductivity. Graphene, as a two-dimensional carbon material, is regarded as an ideal choice for improving the performance of piezoelectric materials due to its excellent electrical conductivity, mechanical strength, and flexibility. Through the modification of graphene, the electrical conductivity of piezoelectric materials can be significantly improved, and at the same time, their flexibility and mechanical strength can also be effectively enhanced.

[0004] Although significant progress has been made in the performance of graphene-modified piezoelectric materials, at present, most piezoelectric-conductive composite materials on the market have problems such as cumbersome preparation processes, high costs, and poor performance stability, which severely limit their application and promotion in the field of flexible electronics.

[0005] In addition, how to effectively apply these materials to actual devices, especially flexible devices that require both piezoelectric and conductive functions, in order to achieve seamless integration with various flexible electronic devices, not only requires the materials to have excellent piezoelectric and conductive properties, but also requires good flexibility and processability, which is still an urgent problem to be solved.

[0006] In this context, the development of a piezoelectric-conductive integrated piezoelectric rubber based on piezoelectric material / graphene modification has become a research hotspot. Based on this, the present application proposes a natural rubber composite modified by graphene based on piezoelectric materials and a preparation method thereof. Summary of the Invention

[0007] In order to solve the problems that current piezoelectric-conductive composite materials cannot meet the requirements of flexible devices for materials with piezoelectric and conductive properties, and also need to have good flexibility and processability, and there are also problems such as cumbersome preparation processes, high costs, and poor performance stability, the present invention provides a natural rubber composite modified by graphene based on piezoelectric materials and a preparation method thereof.

[0008] The present invention is implemented by the following techniques: The present invention provides a preparation method of a natural rubber composite modified by piezoelectric material graphene, comprising the following steps: Comprising the following steps: a, Preparation of piezoelectric-conductive hybrid filler Add piezoelectric particles PZT (lead zirconate titanate) to a sodium hydroxide solution with a concentration of 10% (the concentration is in terms of mass fraction), heat-treat at 60 - 80 °C for 30 min, filter to obtain hydroxylated PZT particles (lead zirconate titanate particles); Add the hydroxylated PZT particles (lead zirconate titanate particles) to a graphene oxide GO slurry with a concentration of 2 wt.%, stir and react at 50 - 60 °C for 2 h to obtain a piezoelectric-conductive composite particle PZT-GO dispersion.

[0009] b, Preparation of three-dimensional structure of piezoelectric-conductive filler Using the ice template method, add the PZT-GO dispersion prepared in step a to a metal container, then place it on an iron column in liquid nitrogen to directionally freeze the PZT-GO dispersion, and freeze-dry to obtain a three-dimensional network structure of PZT-GO piezoelectric-conductive filler, that is, a network of PZT-GO particles with a three-dimensional structure.

[0010] c, Preparation of piezoelectric-conductive rubber Using the ball milling method, take 15 parts of rubber additives and add them to a ball mill, ball mill at 500 rpm for 30 min to obtain a rubber additive dispersion; the rubber additives include 5 parts of zinc oxide, 2 parts of sulfur, 2 parts of vulcanization accelerator, 2 parts of antioxidant RD, 2 parts of antioxidant 4010NA, 2 parts of stabilizer Pingping + O, and the parts are by mass; Add the rubber additive dispersion to 100 parts of a natural rubber latex emulsion with a concentration of 60 wt.%, stir for 30 min, and then add 2 parts of a graphene oxide dispersion with a concentration of 2 wt.% (the parts are by mass) to obtain a mixed dispersion; Add the mixed dispersion to the three-dimensional network structure of PZT-GO piezoelectric-conductive filler prepared in step b, dry, and hot press and vulcanize in air at 120 °C for 2 h to obtain PZT-GO piezoelectric-conductive rubber.

[0011] d, Polarization treatment Put the PZT-GO piezoelectric-conductive rubber prepared in step c into an oil bath at 100 °C, immerse the PZT-GO piezoelectric-conductive rubber completely in silicone oil for polarization, the polarization voltage is 20 KV, and the polarization time is 30 min; The polarized PZT-GO piezoelectric-conductive rubber is ultrasonically cleaned in alcohol for 30 min and then dried in a forced-air drying oven at 80 °C for 30 min to obtain the polarized PZT-GO piezoelectric-conductive rubber.

[0012] The present invention also provides a natural rubber composite material modified with graphene based on piezoelectric materials prepared by the above method, and the thickness of the composite material is 0.3 mm to 3 mm.

[0013] Specifically, the piezoelectric composite material is made of lead zirconate titanate.

[0014] Specifically, the piezoelectric composite material includes 40 wt.% nano piezoelectric particles, 10 wt.% conductive graphene, and 50 wt.% natural rubber.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The preparation method of the natural rubber composite material modified with graphene based on piezoelectric materials provided by the present invention realizes the construction of a three-dimensional piezoelectric-conductive network of piezoelectric materials-graphene by optimizing the material formula and preparation process, and is expected to prepare a piezoelectric-conductive integrated piezoelectric rubber with stable performance, low cost and easy processing through the rubber backfilling method, providing new material support for the development of the flexible electronics field.

[0016] The present invention is not only an urgent need to meet the requirements of new devices for high-performance materials, but also an important direction to promote the technological progress of the flexible electronics field. Description of the Drawings

[0017] Figure 1 In the figure, a represents the SEM image of the GO three-dimensional network structure, b represents the SEM image of the PZT-GO piezoelectric-conductive rubber, and c represents the SEM image of the PZT-GO rubber composite material without a three-dimensional piezoelectric-conductive network structure. Detailed Embodiments

[0018] The following details the specific embodiments of the present invention. Example 1

[0019] A preparation method of a natural rubber composite material modified with graphene based on piezoelectric materials is as follows: a. Preparation of piezoelectric-conductive hybrid filler Piezoelectric particles PZT (lead zirconate titanate) are added to a 10% sodium hydroxide solution and heat-treated at 70 °C for 30 min, and then filtered to obtain hydroxylated PZT particles (lead zirconate titanate particles); The hydroxylated PZT particles (lead zirconate titanate particles) are added to the graphene oxide GO slurry with a concentration of 2 wt.%, and stirred and reacted at 55 °C for 2 h to obtain a piezoelectric-conductive composite particle PZT-GO dispersion liquid.

[0020] b, Preparation of three-dimensional structure of piezoelectric-conductive filler Using the ice-templating method, the PZT-GO dispersion liquid prepared in step a is added to a metal container, and then placed on an iron column in liquid nitrogen to directionally freeze and lyophilize the PZT-GO dispersion liquid, obtaining a three-dimensional network structure of PZT-GO piezoelectric-conductive filler, that is, a network of PZT-GO particles with a three-dimensional structure.

[0021] c, Preparation of piezoelectric-conductive rubber Using the ball milling method, 15 parts of rubber additives are added to a ball mill and ball milled at 500 rpm for 30 min to obtain a rubber additive dispersion liquid; the rubber additives include 5 parts of zinc oxide, 2 parts of sulfur, 2 parts of vulcanization accelerator, 2 parts of antioxidant RD, 2 parts of antioxidant 4010NA, 2 parts of stabilizer Pingping+O, and the parts are by mass; The rubber additive dispersion liquid is added to 100 parts of natural rubber latex emulsion with a concentration of 60 wt.% and stirred for 30 min, and then 2 parts of graphene oxide dispersion liquid with a concentration of 2 wt.% are added, and the parts are by mass, obtaining a mixed dispersion liquid; The mixed dispersion liquid is added to the three-dimensional network structure of PZT-GO piezoelectric-conductive filler prepared in step b, dried, and hot-pressed and vulcanized in air at 120 °C for 2 h to obtain PZT-GO piezoelectric-conductive rubber.

[0022] d, Poling treatment The PZT-GO piezoelectric-conductive rubber prepared in step c is placed in an oil bath at 100 °C, and the PZT-GO piezoelectric-conductive rubber is completely immersed in silicone oil for poling, the poling voltage is 20 KV, and the poling time is 30 min; The poled PZT-GO piezoelectric-conductive rubber is placed in alcohol and ultrasonically cleaned for 30 min, and dried in a forced-air drying oven at 80 °C for 30 min to obtain the poled PZT-GO piezoelectric-conductive rubber. Comparative Example 1

[0023] A preparation method of a composite material, omitting step b, that is, the PZT-GO composite particles do not undergo the construction of a three-dimensional network structure, and the remaining steps are exactly the same as those in Example 1.

[0024] Specifically, it includes the following steps: a, Preparation of piezoelectric-conductive hybrid filler Piezoelectric particles PZT (lead zirconate titanate) were added to a 10% sodium hydroxide solution, heated at 70 °C for 30 min, filtered, and hydroxylated PZT particles (lead zirconate titanate particles) were obtained; The hydroxylated PZT particles (lead zirconate titanate particles) were added to a 2 wt.% graphene oxide GO slurry, stirred and reacted at 55 °C for 2 h to obtain a piezoelectric-conductive composite particle PZT-GO dispersion.

[0025] b, Preparation of piezoelectric-conductive rubber Using the ball milling method, 15 parts of rubber additives were added to a ball mill and ball milled at 500 rpm for 30 min to obtain a rubber additive dispersion; the rubber additives included 5 parts of zinc oxide, 2 parts of sulfur, 2 parts of vulcanization accelerator, 2 parts of antioxidant RD, 2 parts of antioxidant 4010NA, and 2 parts of stabilizer Pingping+O, with the parts by mass; The rubber additive dispersion was added to 100 parts of a 60 wt.% natural rubber latex emulsion and stirred for 30 min, and then 2 parts of a 2 wt.% graphene oxide dispersion, with the parts by mass, were added to obtain a mixed dispersion; The mixed dispersion was added to the PZT-GO dispersion prepared in step a, dried, and hot press vulcanized in air at 120 °C for 2 h to obtain PZT-GO piezoelectric-conductive rubber.

[0026] c, Poling treatment The PZT-GO piezoelectric-conductive rubber prepared in step c was placed in an oil bath at 100 °C, and the PZT-GO piezoelectric-conductive rubber was completely immersed in silicone oil for poling, with a poling voltage of 20 KV and a poling time of 30 min; The poled PZT-GO piezoelectric-conductive rubber was ultrasonically cleaned in alcohol for 30 min and dried in a blast drying oven at 80 °C for 30 min to obtain the poled PZT-GO piezoelectric-conductive rubber. Comparative Example 2

[0027] A preparation method of a composite material, which is different in that graphene oxide GO slurry is not added in step a, that is, only the three-dimensional network structure of PZT particles is constructed without adding GO as the conductive network, and the remaining steps are exactly the same as those in Example 1.

[0028] a, Preparation of piezoelectric-conductive hybrid filler Piezoelectric particles PZT (lead zirconate titanate) were added to a 10% sodium hydroxide solution, heated at 70 °C for 30 min, filtered, and a dispersion of hydroxylated PZT particles (lead zirconate titanate particles) was obtained; b, Preparation of three-dimensional structure of piezoelectric-conductive filler Using the ice-templating method, the PZT dispersion prepared in step a was added to a metal container and then placed on an iron column in liquid nitrogen for directional freezing and freeze-drying of the PZT dispersion to obtain a three-dimensional network structure of PZT piezoelectric filler, i.e., a network of PZT particles with a three-dimensional structure.

[0029] c, Preparation of piezoelectric-conductive rubber Using the ball-milling method, 15 parts of rubber additives were added to a ball mill and ball-milled at 500 rpm for 30 min to obtain a rubber additive dispersion; the rubber additives included 5 parts of zinc oxide, 2 parts of sulfur, 2 parts of vulcanization accelerator, 2 parts of antioxidant RD, 2 parts of antioxidant 4010NA, and 2 parts of stabilizer Pingping + O, with the parts by mass; The rubber additive dispersion was added to 100 parts of a natural rubber latex emulsion with a concentration of 60 wt.% and stirred for 30 min, and then 2 parts of a graphene oxide dispersion with a concentration of 2 wt.% were added, with the parts by mass, to obtain a mixed dispersion; The mixed dispersion was added to the three-dimensional network structure of PZT piezoelectric-conductive filler prepared in step b, dried, and hot-pressed and vulcanized in air at 120 °C for 2 h to obtain PZT-GO piezoelectric-conductive rubber.

[0030] d, Poling treatment The PZT piezoelectric-conductive rubber prepared in step c was placed in an oil bath at 100 °C to polarize the PZT-GO piezoelectric-conductive rubber completely immersed in silicone oil, with a polarization voltage of 20 KV and a polarization time of 30 min; The poled PZT piezoelectric-conductive rubber was ultrasonically cleaned in alcohol for 30 min and dried in a forced-air drying oven at 80 °C for 30 min to obtain the poled PZT piezoelectric-conductive rubber.

[0031] As Figure 1 shown: In b, the PZT particles are dispersed in the rubber matrix, and the presence of GO helps the dispersion of PZT particles. The GO network can provide a conductive channel, which helps to enhance the piezoelectric and conductive properties of the material.

[0032] In c, the surface is smooth and there are no obvious large granular substances. In the absence of a three-dimensional network structure, the dispersion state of PZT particles in the rubber matrix is significantly different. Without the support of the GO three-dimensional network, PZT particles may not be able to work effectively in cooperation when subjected to stress, resulting in a decrease in piezoelectric response.

[0033] The materials prepared in Example 1, Comparative Example 1, and Comparative Example 2 were subjected to performance tests, and the results are shown in the following table: Table 1. Piezoelectric properties of piezoelectric-conductive integrated piezoelectric rubber

[0034] As can be seen from the data in Table 1, in Example 1, a piezoelectric-conductive integrated piezoelectric rubber based on piezoelectric material / graphene modification was used. The chemical bond connection between lead zirconate titanate (PZT) and graphene oxide (GO) was achieved through hydroxylated lead zirconate titanate (PZT). A three-dimensional PZT-GO network was prepared by the ice-templating method, backfilled with natural rubber latex and vulcanized to form a piezoelectric-conductive network integrated piezoelectric rubber, realizing the high strain-high voltage response performance of the flexible piezoelectric sensor. And the maximum open-circuit voltage (V_oc) was 5.0 V, and the maximum short-circuit current (I_sc) was 2.8 μA.

[0035] The mechanical properties of the polarized PZT-GO piezoelectric-conductive rubbers prepared in Example 1 and Comparative Example 1 were tested, and the results are shown in the following table: Table 2. Mechanical properties of piezoelectric-conductive integrated piezoelectric rubber

[0036] As can be seen from the data in Table 2, in Example 1, a three-dimensional PZT-GO network was prepared by the ice-templating method, backfilled with natural rubber latex and vulcanized to form a piezoelectric-conductive network integrated piezoelectric rubber. Compared with Comparative Example 1, its thermal conductivity increased by 24%, indicating that the formation of the three-dimensional network not only increases the piezoelectric-conductive effect of the piezoelectric rubber, but also significantly improves the thermal conductivity of the material due to the formed thermal conductive network. And since the rubber is a film material, its mechanical property is 10.9 MPa. Although it is lower than the mechanical property of hot-pressed natural rubber, it also meets the application requirements of flexible electronic materials.

[0037] The scope of protection claimed by the present invention is not limited to the above specific embodiments. Moreover, for those skilled in the art, the present invention can have various deformations and modifications. Any modification, improvement and equivalent replacement made within the concept and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a natural rubber composite material based on piezoelectric material graphene modification, characterized in that: The following steps are involved: a. Preparation of piezoelectric-conductive mixed fillers The piezoelectric particles PZT were added into a 10% sodium hydroxide solution, heated at 60-80°C for 30 min, and filtered to obtain hydroxylated PZT particles. The hydroxylated PZT particles were added into a graphene oxide GO slurry with a concentration of 2 wt.%, and stirred at 50-60 °C for 2 h to obtain a piezoelectric-conductive composite particle PZT-GO dispersion. b, Preparation of three-dimensional structure of piezoelectric-conductive fillers Using the ice template method, the PZT-GO dispersion prepared in step a is added to a metal container, and then placed on an iron column in liquid nitrogen, and the PZT-GO dispersion is directionally frozen and freeze-dried to obtain a three-dimensional network structure of a PZT-GO piezoelectric-conductive filler; c. Preparation of piezoelectric-conductive rubber By ball milling, 15 parts of rubber additives were taken and ball milled at 500 rpm for 30 min to obtain a rubber additive dispersion; The rubber additive dispersion is added to 100 parts of a natural rubber latex emulsion with a concentration of 60 wt.%, and stirred for 30 minutes, and then 2 parts of a graphene oxide dispersion with a concentration of 2 wt.% are added, and the parts are calculated by mass to obtain a mixed dispersion; The mixed dispersion is added to the three-dimensional network structure of the PZT-GO piezoelectric-conductive filler prepared in step b, dried, and hot-pressed and vulcanized in air at 120° C. for 2 hours to obtain the PZT-GO piezoelectric-conductive rubber; d, Polarization treatment Put the PZT-GO piezoelectric-conductive rubber prepared in step c into an oil bath at 100° C. to polarize the PZT-GO piezoelectric-conductive rubber completely immersed in silicone oil; The polarized PZT-GO piezoelectric-conductive rubber was ultrasonically cleaned in alcohol for 30 min and dried at 80°C for 30 min to obtain the polarized PZT-GO piezoelectric-conductive rubber.

2. The method for preparing a natural rubber composite material based on piezoelectric material graphene modification according to claim 1, characterized in that: In step c, the rubber additives include 5 parts of zinc oxide, 2 parts of sulfur, 2 parts of vulcanization accelerator, 2 parts of antioxidant RD, 2 parts of antioxidant 4010NA, and 2 parts of stabilizer Pingping+O, and the parts are calculated by mass.

3. The method for preparing a natural rubber composite material based on piezoelectric material graphene modification according to claim 1, characterized in that: In step d, the polarization voltage is 20 KV and the polarization time is 30 min.

4. A natural rubber composite material based on piezoelectric material graphene modification prepared according to claim 1.

5. The natural rubber composite material based on piezoelectric material graphene modification according to claim 4, characterized in that: The piezoelectric composite material is made of lead zirconate titanate.

6. The natural rubber composite material based on piezoelectric material graphene modification according to claim 5, characterized in that: The piezoelectric composite material includes 40 wt.% of nano piezoelectric particles, 10 wt.% of conductive graphene, and 50 wt.% of natural rubber.

7. The natural rubber composite material based on piezoelectric material graphene modification according to claim 4, characterized in that: The thickness of the composite material is 0.3 mm to 3 mm.

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