Dielectric near-zero carbon nanotube / polyvinylidene fluoride composite and preparation method
By using vibration milling and hot pressing of carbon nanotubes and polyvinylidene fluoride powder, a near-zero dielectric composite material with low dispersion and wide bandwidth was prepared, solving the problems of large dielectric constant dispersion and small bandwidth, and achieving an improvement in dielectric properties.
Patent Information
- Application Number
- CN202310330744.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-03-28
- Publication Date
- 2026-02-06
- Estimated Expiration
- 2043-03-28
AI Technical Summary
Existing dielectric materials have large dielectric constant dispersion and small near-zero bandwidth, which limits the development and application of near-zero dielectric materials.
A carbon nanotube/polyvinylidene fluoride composite material with near-zero dielectric was prepared by vibratory milling of carbon nanotubes and polyvinylidene fluoride powder followed by hot pressing. By adjusting the amount and distribution of carbon nanotubes, low dispersion and wide bandwidth dielectric properties were achieved.
It achieves near-zero dielectric properties with low dispersion and wide bandwidth. The raw materials are inexpensive and readily available, and the preparation method is simple, making it valuable for industrial production.
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Figure CN116333435B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application belongs to the technical field of composite materials and the technical field of radio frequency electromagnetic materials, and relates to a carbon nanotube / polyvinylidene fluoride composite material with dielectric near zero and a preparation method. BACKGROUND
[0002] The information disclosed in this BACKGROUND section is only for the purpose of increasing the understanding of the general background of the present application and should not be taken as an acknowledgement or any form of suggestion that this information forms prior art that is publicly known in the field.
[0003] The dielectric constant is one of the basic physical parameters of a substance, and can be used to represent the polarization level of the material in an external electric field. When the dielectric constant is close to zero, the material exhibits electromagnetic invisibility, perfect absorption and other effects, thereby playing an important role in the fields of military, optics and communication.
[0004] At present, the realization of the dielectric near zero performance of the material is mainly achieved by introducing a conductive metal phase into an insulating ceramic matrix through impregnation reduction or direct addition process, so as to realize the dielectric near zero. The principle of this method is that when the content of the conductive metal in the ceramic matrix reaches a certain threshold, the Debye relaxation effect of the positive and negative dielectric constants exhibited in the material and the Drude effect of the negative dielectric constant are superimposed on each other, thereby realizing the dielectric near zero. However, the free electron concentration of the metal is too large, which makes the dielectric constant of the material disperse greatly and the near-zero bandwidth is small, thereby limiting the development and application of the dielectric near zero material. SUMMARY
[0005] In order to solve the problems of the prior art, the present application aims to provide a carbon nanotube / polyvinylidene fluoride composite material with dielectric near zero and a preparation method. The carbon nanotube / polyvinylidene fluoride composite material prepared by the present application has low dispersion and wide bandwidth dielectric near zero performance without adding a metal phase.
[0006] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows:
[0007] On the one hand, a preparation method of a carbon nanotube / polyvinylidene fluoride composite material with dielectric near zero is provided. Carbon nanotubes and polyvinylidene fluoride powder are subjected to vibration milling to obtain a mixed powder, and then hot pressing is performed to obtain the carbon nanotube / polyvinylidene fluoride composite material with dielectric near zero.
[0008] In the present application, the content of the carbon nanotubes in the total mass of the carbon nanotubes and the polyvinylidene fluoride powder is 10-15%.
[0009] In the present application, polyvinylidene fluoride is used as the matrix material, which has excellent thermal stability and high dielectric constant, and can provide positive dielectric constant as the matrix to provide Debye relaxation effect. Carbon nanotubes are used as the functional phase, which has a relatively moderate free electron concentration and electron mobility to realize dielectric near zero.
[0010] The application researches and finds that the composite structure of polyvinylidene fluoride and carbon nanotubes and the addition amount of carbon nanotubes affect the performance of the final composite material. First, the application uses vibration milling treatment, which can make the boundary of the PVDF particles in the material, and the carbon nanotubes are distributed in the gap of the PVDF particles, so that the distribution range of the carbon nanotubes is limited to a certain extent, and the application avoids forming an overall percolation network by limiting the distribution of the carbon nanotubes; second, the application adjusts the addition amount of the carbon nanotubes to change the difficulty of forming a percolation network in the material, thereby affecting the negative value of the dielectric constant of the material and the frequency position of the dielectric near-zero point of the material; and finally, the distribution of a specific amount of carbon nanotubes in the polyvinylidene fluoride matrix is fixed by hot pressing, so as to realize the dielectric near-zero performance of low dispersion and wide bandwidth.
[0011] In another aspect, a carbon nanotube / polyvinylidene fluoride composite material with dielectric near-zero is obtained by the above preparation method.
[0012] In a third aspect, the above carbon nanotube / polyvinylidene fluoride composite material with dielectric near-zero is applied in optics and / or communication.
[0013] The application has the following beneficial effects:
[0014] (1) The application first prepares a composite material with dielectric near-zero performance by using carbon nanotubes as a conductive functional phase, adjusting the addition amount of carbon nanotubes, combining vibration milling and hot pressing, and compounding with polyvinylidene fluoride. The method can comprehensively realize the strength of Debye relaxation and free electron Drude oscillation to achieve wider frequency and lower dispersion of dielectric near-zero.
[0015] (2) The raw materials of the application are relatively cheap and easy to obtain, the preparation method is simple, the raw material utilization rate is high, and the application has industrial production value. BRIEF DESCRIPTION OF DRAWINGS
[0016] The drawings accompanying the specification of the application form a part of the application and serve to provide further understanding of the application. The schematic embodiments of the application and the description thereof serve to explain the application and do not constitute an improper limitation on the application.
[0017] Figure 1 The FESEM graph of the carbon nanotube / polyvinylidene fluoride composite material prepared for Example 1 of the application has a magnification of 20,000 times;
[0018] Figure 2 The XRD graph of the carbon nanotube / polyvinylidene fluoride composite material prepared for Example 1 of the application;
[0019] Figure 3 The dielectric properties of the polyvinylidene fluoride composite materials prepared by the application with different carbon nanotube doping amounts. DETAILED DESCRIPTION
[0020] It should be noted that the following detailed description is exemplary in nature and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
[0021] It is also important to note that the terms used herein are not intended to limit the particular embodiments of the present application disclosed in this specification. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and the present disclosure, and will not be interpreted in an overly literal or overly formal sense unless expressly so defined herein.
[0022] In view of the problems of large dielectric constant dispersion and small near-zero bandwidth of the dielectric near-zero material with added metal phase, the present application provides a dielectric near-zero carbon nanotube / polyvinylidene fluoride composite material and a preparation method thereof.
[0023] In a typical embodiment of the present application, a preparation method of a dielectric near-zero carbon nanotube / polyvinylidene fluoride composite material is provided. Carbon nanotubes and polyvinylidene fluoride powder are subjected to vibration milling to obtain a mixed powder, and then hot pressing is performed to obtain the dielectric near-zero carbon nanotube / polyvinylidene fluoride composite material.
[0024] In some embodiments, the carbon nanotubes account for 10-15% of the total mass of the carbon nanotubes and the polyvinylidene fluoride powder.
[0025] In some embodiments, the carbon nanotubes account for 10-14% of the total mass of the carbon nanotubes and the polyvinylidene fluoride powder.
[0026] In some embodiments, the carbon nanotubes account for 10.0-11.0% of the total mass of the carbon nanotubes and the polyvinylidene fluoride powder, preferably 10.0-10.5%, and more preferably 10.0-10.2%.
[0027] In some embodiments, the carbon nanotubes account for 11.5-12.5% of the total mass of the carbon nanotubes and the polyvinylidene fluoride powder, preferably 11.8-12.2%, and more preferably 11.9-12.1%.
[0028] In some embodiments, the carbon nanotubes account for 13.0-14.0% of the total mass of the carbon nanotubes and the polyvinylidene fluoride powder, preferably 13.5-14.0%, and more preferably 13.8-14.0%.
[0029] In some embodiments, the vibration milling cycle is 40-80s, and is performed 1-3 times, and each cycle specifically comprises 4-6Hz vibration for 20-40s and 18-22Hz vibration for 20-40s.
[0030] In some embodiments, the hot-pressing temperature is 160-180℃.
[0031] In some embodiments, the hot-pressing pressure is 8.5-9.5MPa, preferably 8.8-9.2MPa.
[0032] In some embodiments, the hot-pressing time is 15-20min.
[0033] Research shows that the hot-pressing temperature and time will also affect the distribution of carbon nanotubes to some extent, and in some embodiments, the hot-pressing temperature is 160-165℃, and the hot-pressing time is 15-17min.
[0034] In some embodiments, the hot-pressing temperature is 175-180℃, and the hot-pressing time is 15-20min. The hot-pressing time is preferably 15-17min. The hot-pressing time is preferably 18-20min.
[0035] Another embodiment of the present application provides a dielectric near-zero carbon nanotube / polyvinylidene fluoride composite material obtained by the above preparation method.
[0036] In some embodiments, the thickness is 0.5-2mm.
[0037] A third embodiment of the present application provides an application of the above dielectric near-zero carbon nanotube / polyvinylidene fluoride composite material in optics and / or communication.
[0038] In order to enable those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in combination with specific embodiments.
[0039] Embodiment 1
[0040] A method for preparing a negative dielectric constant material by carbon nanotubes and polyvinylidene fluoride, comprising the following steps:
[0041] (1) According to the mass ratio of carbon nanotubes to polyvinylidene fluoride being 1:9, 0.2g of carbon nanotube powder and 1.8g of polyvinylidene fluoride powder are weighed.
[0042] (2) Put the weighed powder of step (1) into the vibration mill tube, and carry out vibration mill mixing at room temperature. The vibration mill cycle is 1 minute, and the process is carried out twice. Each cycle specifically comprises 30 seconds of 5Hz vibration and 30 seconds of 20Hz vibration to obtain carbon nanotube / polyvinylidene fluoride powder.
[0043] (3) Put the powder into a mold to carry out hot-pressing forming.
[0044] The forming pressure is 9Mpa, the hot-pressing temperature is 160℃, the holding time is 15min, and after demolding, a circular sheet with a diameter of 20mm is obtained for further dielectric property testing. The mass fraction of carbon nanotubes is 10%.
[0045] Figure 1 The FESEM image of the carbon nanotube / polyvinylidene fluoride composite material prepared in Example 1 has a magnification of 20000 times. It can be observed that the carbon nanotubes have begun to connect with each other to form a conductive network.
[0046] Figure 2 The XRD image of the carbon nanotube / polyvinylidene fluoride composite material prepared in Example 1 shows that no impurity phase appears in the prepared material, indicating that the product is a high-purity carbon nanotube / polyvinylidene fluoride material.
[0047] Example 2
[0048] A method for preparing a negative dielectric constant material from carbon nanotubes and polyvinylidene fluoride, comprising the following steps:
[0049] (1) According to the mass ratio of carbon nanotubes to polyvinylidene fluoride of 3:22, 0.24g of carbon nanotube powder and 1.76g of polyvinylidene fluoride powder are weighed.
[0050] (2) Put the weighed powder of step (1) into the vibration mill tube, and carry out vibration mill mixing at room temperature. The vibration mill cycle is 1 minute, and the process is carried out twice. Each cycle specifically comprises 30 seconds of 5Hz vibration and 30 seconds of 20Hz vibration to obtain carbon nanotube / polyvinylidene fluoride powder.
[0051] (3) Put the powder into a mold to carry out hot-pressing forming.
[0052] The forming pressure is 9Mpa, the hot-pressing temperature is 160℃, the holding time is 15min, and after demolding, a circular sheet with a diameter of 20mm is obtained for further dielectric property testing. The mass fraction of carbon nanotubes is 12%.
[0053] Example 3
[0054] A method for preparing a negative dielectric constant material from carbon nanotubes and polyvinylidene fluoride, comprising the following steps:
[0055] (1) According to the mass ratio of carbon nanotubes and polyvinylidene fluoride being 7:43, 0.28 g of carbon nanotube powder and 1.72 g of polyvinylidene fluoride powder are weighed.
[0056] (2) The powder weighed in step (1) is placed in a vibration mill tube, and vibration mill mixing is carried out at room temperature, with a vibration mill cycle of 1 minute, for 2 times, with each cycle being 30 seconds of 5 Hz vibration and 30 seconds of 20 Hz vibration, to obtain carbon nanotube / polyvinylidene fluoride powder.
[0057] (3) The powder is placed in a mold for hot pressing.
[0058] The molding pressure is 9 Mpa, the hot pressing temperature is 160°C, the holding time is 15 min, and after demolding, a circular sheet with a diameter of 20 mm is obtained for further dielectric property testing, wherein the mass fraction of carbon nanotubes is 14%.
[0059] Figure 3 The dielectric properties of polyvinylidene fluoride composites prepared in Example 1, Example 2, and Example 3 with different doping amounts of carbon nanotubes are tested. In the sample with 10% carbon nanotube content, dielectric near-zero performance appears in the corresponding test frequency band. At the same time, compared with the ten-to-the-fourth-to-the-fifth power magnitude dielectric constant dispersion range of the metal phase dielectric near-zero material, the dispersion range of this example is ten-to-the-second-to-the-third power, which greatly reduces the dispersion and significantly increases the bandwidth.
[0060] Example 4
[0061] A method for preparing a negative dielectric constant material from carbon nanotubes and polyvinylidene fluoride, comprising the following steps:
[0062] (1) According to the mass ratio of carbon nanotubes and polyvinylidene fluoride being 1:9, 0.2 g of carbon nanotube powder and 1.8 g of polyvinylidene fluoride powder are weighed.
[0063] (2) The powder weighed in step (1) is placed in a vibration mill tube, and vibration mill mixing is carried out at room temperature, with a vibration mill cycle of 1 minute, for 2 times, with each cycle being 30 seconds of 5 Hz vibration and 30 seconds of 20 Hz vibration, to obtain carbon nanotube / polyvinylidene fluoride powder.
[0064] (3) The powder is placed in a mold for hot pressing.
[0065] The molding pressure is 9 Mpa, the hot pressing temperature is 160°C, the holding time is 20 min, and after demolding, a circular sheet with a diameter of 20 mm is obtained for further dielectric property testing, wherein the mass fraction of carbon nanotubes is 10%.
[0066] Example 5
[0067] A method for preparing a negative dielectric constant material by using carbon nanotubes and polyvinylidene fluoride, comprising the following steps:
[0068] (1) According to the mass ratio of carbon nanotubes to polyvinylidene fluoride being 1:9, 0.2g of carbon nanotube powder and 1.8g of polyvinylidene fluoride powder are weighed.
[0069] (2) The powder weighed in step (1) is put into a vibration mill tube, and vibration mill mixing is carried out at room temperature, with a vibration mill cycle of 1 minute, for 2 times, with each cycle being 30 seconds of 5Hz vibration and 30 seconds of 20Hz vibration, to obtain carbon nanotube / polyvinylidene fluoride powder.
[0070] (3) The powder is put into a mold for hot pressing.
[0071] Among them, the molding pressure is 9Mpa, the hot pressing temperature is 180℃, the holding time is 15min, and after demolding, it is a circular sheet with a diameter of 20mm, for further dielectric property testing, wherein the mass fraction of carbon nanotubes is 10%.
[0072] Example 6
[0073] A method for preparing a negative dielectric constant material by using carbon nanotubes and polyvinylidene fluoride, comprising the following steps:
[0074] (1) According to the mass ratio of carbon nanotubes to polyvinylidene fluoride being 1:9, 0.2g of carbon nanotube powder and 1.8g of polyvinylidene fluoride powder are weighed.
[0075] (2) The powder weighed in step (1) is put into a vibration mill tube, and vibration mill mixing is carried out at room temperature, to obtain carbon nanotube / polyvinylidene fluoride powder.
[0076] (3) The powder is put into a mold for hot pressing.
[0077] Among them, the molding pressure is 9Mpa, the hot pressing temperature is 180℃, the holding time is 20min, and after demolding, it is a circular sheet with a diameter of 20mm, for further dielectric property testing, wherein the mass fraction of carbon nanotubes is 10%.
[0078] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.
Claims
1. A method for preparing a carbon nanotube / polyvinylidene fluoride composite material with near-zero dielectric strength, characterized in that, Carbon nanotubes and polyvinylidene fluoride powder are subjected to vibration milling to obtain a mixed powder, which is then hot-pressed to form the final product. The vibration mill cycle is 40-80 seconds, and it is performed 1-3 times. Each cycle consists of 20-40 seconds of 4-6 Hz vibration and 20-40 seconds of 18-22 Hz vibration. The pressure during hot pressing is 8.5~9.5 MPa; The carbon nanotubes are 10.0% of the total mass of carbon nanotubes and polyvinylidene fluoride powder.
2. The method for preparing the near-zero dielectric carbon nanotube / polyvinylidene fluoride composite material as described in claim 1, characterized in that, The temperature for hot pressing is 160~180℃; Alternatively, the hot pressing time is 15~20 min.
3. The method for preparing the near-zero dielectric carbon nanotube / polyvinylidene fluoride composite material as described in claim 1, characterized in that, The pressure for hot pressing is 8.8~9.2 MPa.
4. The method for preparing the near-zero dielectric carbon nanotube / polyvinylidene fluoride composite material as described in claim 1, characterized in that, The hot pressing temperature is 160~165℃, and the hot pressing time is 15~17 min.
5. The method for preparing the near-zero dielectric carbon nanotube / polyvinylidene fluoride composite material as described in claim 1, characterized in that, The hot pressing temperature is 175~180℃, and the hot pressing time is 15~20 min.
6. The method for preparing the near-zero dielectric carbon nanotube / polyvinylidene fluoride composite material as described in claim 1, characterized in that, The hot pressing time is 15~17 min.
7. The method for preparing the near-zero dielectric carbon nanotube / polyvinylidene fluoride composite material as described in claim 1, characterized in that, The hot pressing time is 18~20 min.
8. A carbon nanotube / polyvinylidene fluoride composite material with near-zero dielectric, characterized in that, Obtained by the preparation method described in any one of claims 1 to 7.
9. The near-zero dielectric carbon nanotube / polyvinylidene fluoride composite material as described in claim 8, characterized in that, The thickness is 0.5~2 mm.
10. The application of a near-zero dielectric carbon nanotube / polyvinylidene fluoride composite material as described in claim 8 or 9 in optics and / or communications.