Highly thermally conductive and electrically insulating polymer composites with oriented, isolated dual-filler networks

Abstract

The present invention provides a highly thermally conductive and electrically insulating polymer composite material with an oriented, isolated dual-filler network. Using carbon nanotubes and boron nitride as dual fillers, the composite material is successfully prepared through melt blending, mechanical blending, annealing, and orientation structure control. This composite material exhibits high thermal conductivity and electrical insulation properties at relatively low filler loadings. The preparation process is simple and easy to operate, and can be produced using existing equipment, facilitating widespread application.

Description

Technical Field

[0001] The invention relates to a high-thermal-conductivity and electrically-insulating polymer composite material with an oriented isolation double-filler network, and belongs to the field of preparation of polymer composite materials. Background Art

[0002] Electronic devices are becoming increasingly multifunctional, miniaturized, and integrated, which places more stringent demands on the heat dissipation of the devices and, therefore, on the performance of thermal conductive materials. Compared with metal-based and ceramic-based thermal conductive materials, polymer-based thermal conductive materials have the advantages of light weight, easy processing, good insulation and corrosion resistance, and have been widely used in application fields such as electronic packaging and thermal management. However, with the rapid development of electronic devices, the amount of discarded plastic waste has also increased. If not handled properly, it will cause serious environmental pollution, which has caused people's concern. Therefore, using biodegradable polymers to replace traditional non-degradable plastics to manufacture biodegradable polymer-based composite materials with good thermal conductivity and electrical insulation is considered to be a feasible way to solve the above problems.

[0003] Biodegradable polymer materials (such as polylactic acid and polybutylene succinate) offer properties not found in traditional petroleum-based plastics, such as being green, environmentally friendly, made from renewable raw materials, and biodegradable. However, these biodegradable polymers often exhibit extremely low intrinsic thermal conductivity, necessitating improvements in their thermal conductivity. Over the past few decades, highly thermally conductive fillers (such as silicon carbide, aluminum oxide, aluminum nitride, and boron nitride) have been widely used to enhance the thermal conductivity of biodegradable polymers. However, these materials require large amounts of fillers at high loadings to achieve the desired effect, significantly reducing the mechanical properties of the composite and increasing processing difficulty. To address this issue, highly conductive fillers (such as carbon nanotubes and graphene) have been used in place of these fillers to achieve good thermal conductivity at lower loadings. However, these highly conductive fillers, while altering the thermal conductivity, also alter the electrical insulation properties of the polymer, resulting in, for example, extremely high electrical conductivity and a higher dielectric constant.

[0004] Research has found that by constructing a unique, isolated dual-network structure within polymer-based composites, the synergistic efficiency of fillers can be effectively utilized, significantly improving the thermal conductivity of polymer materials. For example, in a polystyrene matrix, multi-walled carbon nanotube fillers form thermal conductive network 1, while hexagonal boron nitride adheres to the surface of the binary blend particles to form thermal conductive network 2. Thermal conductive network 1 is isolated between the binary blend particles, and thermal conductive network 1 and thermal conductive network 2 are interconnected, giving the two fillers a higher synergistic efficiency and thus improving the thermal conductivity of the material (ZL201710270567.4). At the same time, it was also discovered that a nylon 6 / graphene nanosheet@hexagonal boron nitride composite material with an isolated double network structure was prepared by combining melt blending, coating, and hot pressing. The hexagonal boron nitride network maximizes the contact area through the interconnection of fillers. The embedded graphene nanosheet network increases the density of the thermal conductive network and serves as a bridge connecting the hexagonal boron nitride thermal conductive network, significantly improving the thermal conductivity while maintaining electrical insulation to the maximum extent. This successfully gives the nylon 6 material the characteristics of high thermal conductivity and electrical insulation. However, in the above system, in order to achieve high thermal conductivity and electrical insulation, it is still necessary to add a relatively high total filler content, which will lead to a decrease in the mechanical properties of the composite material, increase processing difficulty, and increase preparation cost. Summary of the Invention

[0005] To overcome the above-mentioned shortcomings of the prior art, the present invention utilizes multi-walled carbon nanotubes and boron nitride powder as fillers, combined with melt blending, mechanical blending, hot pressing, annealing, and orientation structure control processes to produce a biodegradable polymer composite with an oriented, isolated double network structure. This composite exhibits high strength, high thermal conductivity, and high electrical insulation properties at a relatively low filler content.

[0006] The specific technical solutions adopted in the present invention are as follows:

[0007] The present invention provides a high thermal conductivity and electrically insulating polymer composite material having an oriented isolation dual filler network. The high thermal conductivity and electrically insulating polymer composite material having an oriented isolation dual filler network is prepared by the following method:

[0008] (1) melt-blending polybutylene succinate resin and multi-walled carbon nanotubes, crushing and sieving the resulting mixture to obtain a polybutylene succinate / carbon nanotube composite masterbatch with a particle size of 500 to 800 μm; the volume of the polybutylene succinate resin is 95-99.5% (preferably 97%) of the total volume of the polybutylene succinate resin and the multi-walled carbon nanotubes;

[0009] (2) mechanically blending the polybutylene succinate / carbon nanotube composite masterbatch described in step (1) with boron nitride powder to obtain polybutylene succinate / carbon nanotube@boron nitride composite particles; the volume ratio of the polybutylene succinate / carbon nanotube composite masterbatch to the boron nitride powder is 100:5-20 (preferably 100:15);

[0010] (3) The polybutylene succinate / carbon nanotube@boron nitride composite particles described in step (1) are sequentially subjected to hot pressing, annealing treatment, and cutting, and the obtained sample is subjected to orientation structure regulation in the length direction in a mold to obtain the high thermal conductivity and electrically insulating polymer composite material with an oriented isolation dual filler network; wherein the annealing temperature is 115-125°C (preferably 120°C), the pressure is 4.5-5.5MPa (preferably 5MPa), and the annealing time is 1.5-2h (preferably 2h); the processing temperature for the orientation structure regulation is 80-100°C (preferably 80°C), the pressure is 30-100MPa (preferably 100MPa), the width of the sample is equal to the groove width of the mold, and the ratio of the thickness of the sample to the high thermal conductivity and electrically insulating polymer composite material with an oriented isolation dual filler network is 1.8-2.5:1 (preferably 2:1). That is, when the orientation structure is regulated, the orientation structure regulation is completed when the height of the material is pressed to 1 / 1.8-2.5 of the original height.

[0011] Furthermore, the melt blending in step (1) is performed in a torque rheometer. The present invention recommends that the melt blending temperature be 135-145°C, the mixing speed be 55-60 r / min, and the mixing time be 4-5 min. In one embodiment of the present invention, the melt blending temperature is 140°C, the mixing speed is 60 r / min, and the mixing time is 5 min to obtain a mixture.

[0012] Furthermore, the present invention recommends that the mechanical blending in step (2) be performed in a high-speed mixer at a speed of 18,000-20,000 rpm for 1.5-2.5 min. In one embodiment of the present invention, the mechanical blending speed is 20,000 rpm for 2 min to ensure sufficient mixing.

[0013] Furthermore, the present invention recommends that the hot pressing molding in step (3) be performed in a flat-plate vulcanizer at a temperature of 135-145°C (preferably 140°C), a pressure of 8-10 MPa (preferably 10 MPa), and a time of 4.5-5.5 minutes (preferably 5 minutes). In one embodiment of the present invention, the horizontal cross-sectional dimensions of the mold are 120 mm x 30 mm.

[0014] Preferably, the orientation structure control in step (3) is carried out on a flat-plate vulcanizing press at a processing temperature of 80° C. and a pressure of 100 MPa.

[0015] In the research of polybutylene succinate-based thermal conductive materials, there have been many studies on the preparation of composite materials by mixing polymers with thermally conductive fillers, such as polybutylene succinate / reduced graphene oxide, polybutylene succinate / alumina, and polybutylene succinate / boron nitride. However, to achieve high thermal conductivity, a large amount of filler is required. High filler content can affect other properties of the composite material. In particular, at high filler loadings, nanofillers tend to agglomerate, which affects mechanical properties, processing performance, and production costs.

[0016] Compared with the prior art, the present invention has the following characteristics and beneficial effects:

[0017] (1) Using carbon nanotubes and boron nitride as dual fillers, a composite material with an oriented, isolated dual network structure was successfully prepared through processes such as melt blending, mechanical blending, annealing, and orientation structure control. This composite material exhibits high thermal conductivity and electrical insulation properties at low filler loadings. The preparation process is simple and easy to operate, and can be produced using existing equipment, which is conducive to its widespread application.

[0018] (2) The carbon nanotube network is constructed in the polymer through melt blending, and the boron nitride isolation network is then constructed through mechanical blending. Combining the two simple operations of melt blending and mechanical blending, the polymer material is given high thermal conductivity while maintaining its electrical insulation advantages. At the same time, the mechanical properties of the composite material are significantly improved by regulating the orientation structure, overcoming the defect of the composite material's mechanical properties being reduced due to the addition of fillers. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 These are SEM images of the polybutylene succinate composite materials prepared in Comparative Example 3(a), Example 3(b), Comparative Example 4(c) and Example 4(d).

[0020] Figure 2 This is a comparison chart of the thermal conductivity of the polybutylene succinate composite materials prepared in Examples 1-5 and Comparative Examples 1-5.

[0021] Figure 3 This is a comparison chart of the electrical conductivity of the polybutylene succinate composite materials prepared in Comparative Example 6, Comparative Examples 1-5, and Examples 1-5. DETAILED DESCRIPTION

[0022] The fully dried polybutylene succinate pellets (Xinjiang Lanshan Tunhe Polyester Co., Ltd., brand TH801, density 1.25 g / cm 3, melting point 113 ℃, melt index 10-20g / 10min) and multi-walled carbon nanotubes (Xianfeng Nano, XFM15, diameter 10-20nm, length 10-30μm, carboxyl content 2.0wt%) were melt-blended in a torque rheometer, wherein the content of multi-walled carbon nanotubes was 0.5, 1, 3 and 5vol%, respectively. The melt blending conditions were: temperature 140 ℃, rotation speed 60r / min, and blending time 5min. By measuring the electrical conductivity of the above four groups of composite materials and pure polybutylene succinate, it was found that the electrical conductivity of the composite material suddenly changed when the filler addition amount was 3vol%, and the electrical conductivity reached 0.02S / cm, proving that the carbon nanotube filler network in the composite material was successfully constructed at this time. Therefore, 3vol% was selected as the multi-walled carbon nanotube network content in the oriented isolated double network structure.

[0023] The technical solution of the present invention will be further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0024] Example 1

[0025] (1) Polybutylene succinate (Xinjiang Lanshan Tunhe Polyester Co., Ltd., brand TH801, density 1.25 g / cm 3 , melting point 113°C, melt index 10-20 g / 10 min), multi-walled carbon nanotubes (Xianfeng Nano, XFM15, diameter 10-20 nm, length 10-30 μm, carboxyl content 2.0 wt%) were dried in a 60°C forced air oven for 12 h.

[0026] (2) After sufficient drying, 97 parts by volume of polybutylene succinate pellets and 3 parts by volume of multi-walled carbon nanotubes (content: 3 vol%) were melt-blended in a torque rheometer. The melt-blending conditions were: temperature 140°C, rotation speed 60 r / min, and blending time 5 min to obtain polybutylene succinate / carbon nanotube composite particles.

[0027] (3) The dried polybutylene succinate / carbon nanotube composite particles were placed in a grinder for liquid nitrogen pulverization, and after screening and collection, composite particles with a particle size of 500 to 800 μm were obtained, and the composite particles were placed in a 60° C. forced air oven for drying for 12 h.

[0028] (4) The composite particles prepared in the above (3) were hot-pressed in a flat-plate vulcanizer at a temperature of 140°C and a pressure of 10 MPa to obtain a sheet with a size of 120 mm × 30 mm × 30 mm. The sheet was then annealed at 120°C and 5 MPa for 2 h and naturally cooled to room temperature.

[0029] (5) The annealed sheet was mechanically cut to obtain a sample with a size of 40 mm × 30 mm × 30 mm. The orientation structure was then regulated. The cut sample was placed in the mold cavity of the mold under the orientation structure regulation. The mold cavity size was 120 mm × 30 mm × 30 mm. The upper and lower molds formed a piston-like structure. After applying pressure, the sample was restricted in the width direction, but could flow and extend in the length direction. The compression ratio of the sample was controlled at 1:2, and finally a polybutylene succinate / carbon nanotube composite material with an oriented isolated double network structure was obtained. The specific operation was as follows: the sample was placed in the center of the mold cavity, placed on a flat vulcanizer and preheated at the processing temperature for 10 minutes, the flat vulcanizer was set to pressurize to the processing pressure, and the pressure was maintained for 3 minutes. The processing temperature was 80 ° C and the processing pressure was 100 MPa. Under the action of pressure and temperature, the sample will flow and deform along the length direction. After cooling to room temperature under pressure, the sample was taken out and the sample height was measured. The above operation was repeated until the sample height reached 15 mm, that is, the compression ratio of 1:2 was achieved.

[0030] Comparative Example 1

[0031] (1) Polybutylene succinate (Xinjiang Lanshan Tunhe Polyester Co., Ltd., brand TH801, density 1.25 g / cm3, melting point 113°C, melt index 10-20 g / 10 min) and multi-walled carbon nanotubes (Xianfeng Nano, XFM15, diameter 10-20 nm, length 10-30 μm, carboxyl content 2.0 wt%) were dried in a forced air oven at 60°C for 12 h.

[0032] (2) After sufficient drying, 97 parts by volume of polybutylene succinate pellets and 3 parts by volume of multi-walled carbon nanotubes (content: 3 vol%) were melt-blended in a torque rheometer. The melt-blending conditions were: temperature 140°C, rotation speed 60 r / min, and blending time 5 min to obtain polybutylene succinate / carbon nanotube composite particles.

[0033] (3) The dried polybutylene succinate / carbon nanotube composite particles were placed in a grinder for liquid nitrogen pulverization, and after screening and collection, composite particles with a particle size of 500 to 800 μm were obtained, and the composite particles were placed in a 60° C. forced air oven for drying for 12 h.

[0034] (4) The composite particles prepared in the above (3) were hot-pressed in a flat-plate vulcanizer at a temperature of 140°C and a pressure of 10 MPa to obtain a sheet with a size of 120 mm × 30 mm × 30 mm. The sheet was then annealed at 120°C and 5 MPa for 2 h and naturally cooled to room temperature to obtain a composite material.

[0035] Examples 2-5

[0036] (1) Polybutylene succinate (Xinjiang Lanshan Tunhe Polyester Co., Ltd., brand TH801, density 1.25 g / cm 3 , melting point 113 ° C, melt index 10-20 g / 10 min), multi-walled carbon nanotubes (Xianfeng Nano, XFM15, diameter 10-20 nm, length 10-30 μm, carboxyl content 2.0 wt %) and boron nitride (Shandong Pengcheng Ceramic New Material Technology Co., Ltd., size 15-20 μm) were dried in a 60 ° C forced air oven for 12 h.

[0037] (2) After sufficient drying, 97 parts by volume of polybutylene succinate pellets and 3 parts by volume of multi-walled carbon nanotubes (3 vol%) were melt-blended in a torque rheometer. The melt-blending conditions were: temperature 140°C, rotation speed 60 r / min, and blending time 5 min to obtain polybutylene succinate / carbon nanotube composite particles.

[0038] (3) The dried polybutylene succinate / carbon nanotube composite particles were placed in a grinder for liquid nitrogen pulverization, and after screening and collection, composite particles with a particle size of 500 to 800 μm were obtained, and the composite particles were placed in a 60° C. forced air oven for drying for 12 h.

[0039] (4) After sufficient drying, 100 parts by volume of the polybutylene succinate / carbon nanotube composite particles were mechanically mixed with boron nitride powder in a high-speed mixer, wherein the boron nitride powder was added in amounts of 5 parts by volume (5 vol%), 10 parts by volume (10 vol%), 15 parts by volume (15 vol%), and 20 parts by volume (20 vol%), respectively. The mechanical mixing conditions were: a rotation speed of 20,000 r / min and a mixing time of 2 min.

[0040] (5) The composite prepared in (4) was hot-pressed in a flat-plate vulcanizer at a temperature of 140°C and a pressure of 10 MPa to obtain a sheet with a size of 120 mm × 30 mm × 30 mm. The sheet was then annealed at 120°C and 5 MPa for 2 h and naturally cooled to room temperature.

[0041] (6) The annealed sheet was mechanically cut to obtain a sample with a size of 40mm×30mm×30mm, and then the orientation structure was controlled. The cut sample was placed in the mold cavity of the orientation structure controlled mold. The mold cavity size was 120mm×30mm×30mm. The upper and lower molds formed a piston-like structure. After pressure was applied, the sample was restricted in the width direction, but could flow and extend in the length direction. The compression ratio of the sample was controlled at 1:2, and finally a polybutylene succinate / carbon nanotube@boron nitride composite material with an oriented isolation double network structure was obtained. The specific operation is as follows: the sample was placed in the center of the mold cavity, placed on a flat vulcanizer and preheated at the processing temperature for 10 minutes, and the flat vulcanizer was set to pressurize to the processing pressure and maintain pressure for 3 minutes. The processing temperature was 80℃ and the processing pressure was 100MPa. Under the action of pressure and temperature, the sample will flow and deform along the length direction. After cooling to room temperature under pressure, the sample was taken out and the sample height was measured. The above operation was repeated until the sample height reached 15mm, that is, the compression ratio of 1:2 was achieved.

[0042] Comparative Examples 2-5

[0043] (1) Polybutylene succinate (Xinjiang Lanshan Tunhe Polyester Co., Ltd., brand TH801, density 1.25 g / cm3, melting point 113°C, melt index 10-20 g / 10 min), multi-walled carbon nanotubes (Xianfeng Nano, XFM15, diameter 10-20 nm, length 10-30 μm, carboxyl content 2.0 wt%) and boron nitride (Shandong Pengcheng Ceramic New Material Technology Co., Ltd., size 15-20 μm) were dried in a forced air oven at 60°C for 12 h.

[0044] (2) After sufficient drying, 97 parts by volume of polybutylene succinate pellets and 3 parts by volume of multi-walled carbon nanotubes (3 vol%) were melt-blended in a torque rheometer. The melt-blending conditions were: temperature 140°C, rotation speed 60 r / min, and blending time 5 min to obtain polybutylene succinate / carbon nanotube composite particles.

[0045] (3) The dried polybutylene succinate / carbon nanotube composite particles were placed in a grinder for liquid nitrogen pulverization, and after screening and collection, composite particles with a particle size of 500 to 800 μm were obtained, and the composite particles were placed in a 60° C. forced air oven for drying for 12 h.

[0046] (4) After sufficient drying, 100 parts by volume of the polybutylene succinate / carbon nanotube composite particles were mechanically mixed with boron nitride powder in a high-speed mixer, wherein the boron nitride powder was added in amounts of 5 parts by volume (5 vol%), 10 parts by volume (10 vol%), 15 parts by volume (15 vol%), and 20 parts by volume (20 vol%), respectively. The mechanical mixing conditions were: a rotation speed of 20,000 r / min and a mixing time of 2 min.

[0047] (5) The composite material prepared in (4) was hot-pressed in a flat-plate vulcanizer at a temperature of 140°C and a pressure of 10 MPa to obtain a sheet with a size of 120 mm × 30 mm × 30 mm. The sheet was then annealed at 120°C and 5 MPa for 2 h and naturally cooled to room temperature to obtain a composite material.

[0048] Comparative Example 6

[0049] (1) Polybutylene succinate (Xinjiang Lanshan Tunhe Polyester Co., Ltd., brand TH801, density 1.25 g / cm3, melting point 113°C, melt index 10-20 g / 10 min) was dried in a forced air oven at 60°C for 12 h.

[0050] (2) The dried polybutylene succinate was hot-pressed in a flat-plate vulcanizer at a temperature of 140°C and a pressure of 10 MPa to obtain a sheet with a size of 120 mm × 30 mm × 30 mm. The sheet was then annealed at 120°C and 5 MPa for 2 h and naturally cooled to room temperature to obtain a pure polybutylene succinate sheet.

[0051] The examples 3-4 and comparative examples 3-4 were mechanically cut and their cross-sectional micromorphologies were characterized using a desktop scanning electron microscope. Figure 1 .from Figure 1 As can be seen in the figure, when the boron nitride content reaches 10 vol%, the polybutylene succinate / multi-walled carbon nanotube composite particles are almost completely coated. The boron nitride has formed a complete isolation layer on the particle surface, and a complete isolation network has been formed between the isolation zones. Because the bonding between the particles is isolated by the boron nitride layer, numerous voids and defects can be observed in the cross-sectional micromorphology. After the orientation structure is controlled, the sample structure is clearly oriented, the voids and defects are reduced, and the overall structure becomes more compact.

[0052] The thermal conductivity in the flow and normal directions of Examples 1-5, as well as the thermal conductivity of Comparative Examples 1-5 and Comparative Example 6 (pure polybutylene succinate), was characterized using an LFA467 laser thermal conductivity meter. The test sample size was standard: 12.7 mm diameter discs. The test temperature was 20°C. The samples were mechanically cut into 1-2 mm blocks and polished using 2000 grit sandpaper on a sample polisher. After polishing, the samples were mechanically cut into 12.7 mm diameter discs, which were then carbon-sprayed and ready for testing.

[0053] The test results are as follows Figure 2 shown.

[0054] The thermal conductivity of Comparative Example 6 (pure polybutylene succinate) is 0.2 W·m -1 ·K -1 .from Figure 2 As can be seen in the figure, the thermal conductivity of the composite material increases linearly with the increase of the boron nitride content. After the orientation structure is regulated, the thermal conductivity of the composite material along the flow direction and the normal direction is significantly different. The thermal conductivity in the flow direction is greatly improved, while the thermal conductivity along the normal direction is reduced. The thermal conductivity shows obvious anisotropy. Boron nitride is a particle that is approximately disc-shaped. Its shape and thermal conductivity are anisotropic. The thermal conductivity of boron nitride in the in-plane direction is 600W·m -1 ·K -1 , while the thermal conductivity in the out-of-plane direction is only 30 W·m -1 ·K -1 The difference is huge, so the orientation arrangement of boron nitride can greatly improve the thermal conductivity. The constructed carbon nanotube and boron nitride dual network can effectively reduce the interfacial thermal resistance. After the orientation structure is regulated, the interconnectivity of the boron nitride network is improved, and a heat conduction path similar to an optical fiber is formed in both directions along the flow direction, making the boron nitride content have a more important influence on the thermal conductivity. With the increase of the boron nitride content, the thermal conductivity of Example 5 along the flow direction reaches a maximum of 2.2W·m -1 ·K -1 , the thermal conductivity is increased by 10 times compared with pure polybutylene succinate.

[0055] The conductivity of the polybutylene succinate materials prepared in Examples 1-5, Comparative Examples 1-5, and Comparative Example 6 (pure polybutylene succinate) was tested. The conductivity of the composite materials was measured using a four-probe tester and an insulation resistance tester. -6 The conductivity data of S / cm was measured using a high resistance meter, and the conductivity was higher than 10 -6 The S / cm of the samples was measured using a four-probe tester.

[0056] The test results are as follows Figure 3As shown, the conductivity of pure polybutylene succinate is 2.5×10 -14 S / cm, the conductivity of the composite material formed by adding 3vol% multi-walled carbon nanotubes increased to 0.02S / cm. In the construction of the oriented isolation double network, the conductive path of the composite material was cut off by using boron nitride to coat polybutylene succinate / multi-walled carbon nanotube particles to reduce the conductivity of the composite material. The conductivity of the composite material decreased linearly with the increase of boron nitride content, indicating that the isolation network of boron nitride was gradually constructed and improved. When the boron nitride addition reached 20vol%, the conductivity of the composite material was still 10 -7 S / cm, and it is generally believed that the electrical conductivity of the material is only less than 10 -9 S / cm is considered an insulating material, which means it still does not reach the insulation level. Oriented structure regulation achieves a synergistic effect between the destruction of the internal conductive network and the severing of the conductive network by the external isolation structure, and the composite material achieves electrical insulation at different boron nitride content.

[0057] Comparative Example 7

[0058] (1) Polybutylene succinate pellets (Xinjiang Lanshan Tunhe Polyester Co., Ltd., brand TH801, density 1.25 g / cm3, melting point 113°C, melt index 10-20 g / 10 min), multi-walled carbon nanotubes (Xianfeng Nano, XFM15, diameter 10-20 nm, length 10-30 μm, carboxyl content 2.0 wt%) and boron nitride (Shandong Pengcheng Ceramic New Material Technology Co., Ltd., size 15-20 μm) were dried in a 60°C forced air oven for 12 h.

[0059] (2) The polybutylene succinate pellets were placed in a grinder and pulverized with liquid nitrogen. After screening and collection, particles with a particle size of 500 to 800 μm were obtained, and the particles were placed in a 60° C. forced air oven and dried for 12 h.

[0060] (3) The dried polybutylene succinate particles, multi-walled carbon nanotubes and boron nitride powder were mechanically mixed in a high-speed mixer at the same volume ratio as in Example 2. The speed of the high-speed mixer was 20,000 r / min and the mixing time was 2 min.

[0061] (4) The prepared composite particles were hot-pressed in a flat-plate vulcanizer at a temperature of 140°C and a pressure of 10 MPa to obtain a sheet with a size of 120 mm × 30 mm × 30 mm. The sheet was then annealed at 120°C and 5 MPa for 2 h and naturally cooled to room temperature to obtain a polybutylene succinate@carbon nanotube@boron nitride composite material.

[0062] Comparative Example 8

[0063] (1) Polybutylene succinate pellets (Xinjiang Lanshan Tunhe Polyester Co., Ltd., brand TH801, density 1.25 g / cm 3 , melting point 113 ° C, melt index 10-20 g / 10 min), multi-walled carbon nanotubes (Xianfeng Nano, XFM15, diameter 10-20 nm, length 10-30 μm, carboxyl content 2.0 wt %) and boron nitride (Shandong Pengcheng Ceramic New Material Technology Co., Ltd., size 15-20 μm) were dried in a 60 ° C forced air oven for 12 h.

[0064] (2) The dried polybutylene succinate particles, multi-walled carbon nanotubes, and boron nitride powder were melt blended in a torque rheometer in the same volume ratio as in Example 2 to obtain a composite. The melt blending conditions were: temperature 140° C., rotation speed 60 r / min, and blending time 5 min.

[0065] (3) The prepared composite was hot-pressed in a flat-plate vulcanizer at a temperature of 140°C and a pressure of 10 MPa to obtain a sheet with a size of 120 mm × 30 mm × 30 mm. The sheet was then annealed at 120°C and 5 MPa for 2 h and naturally cooled to room temperature to obtain a polybutylene succinate / carbon nanotube / boron nitride composite material.

[0066] The polybutylene succinate materials prepared in Comparative Examples 7 and 8 were tested for electrical conductivity, and the electrical conductivity of the composite materials was measured using a four-probe tester and an insulation resistance tester. The thermal conductivity of Comparative Examples 7 and 8 was characterized using an LFA467 laser thermal conductivity meter. The test sample size was the standard sample size: a disc with a diameter of 12.7 mm, and the test temperature was 20°C. The sample was mechanically cut into 1-2 mm blocks, and the surface was polished using 2000 mesh sandpaper on a sample polishing machine. After the sample was polished, it was mechanically cut into discs with a diameter of 12.7 mm, and then the surface was carbon-sprayed before testing. The test results are compared with those of Comparative Example 6, Comparative Example 2-5, and Example 2-5 as shown in the following table:

[0067]

[0068] Composite materials obtained by direct melt blending and mechanical blending of polybutylene succinate, multi-walled carbon nanotubes, and boron nitride exhibited significantly higher electrical conductivity than the composite materials obtained by the methods of Examples 2-5, demonstrating that the processing method, particularly the step of regulating the orientation structure, plays a significant role in enhancing the insulating properties of boron nitride fillers. Direct melt blending or mechanical blending of polybutylene succinate with the two aforementioned fillers improved the thermal conductivity of the materials to a certain extent, but still lagged behind samples with regulated orientation structure. This demonstrates that constructing a dual network of carbon nanotubes and boron nitride, and regulating the orientation structure to enhance the interconnectivity of the boron nitride network, is more effective in improving the thermal conductivity of polybutylene succinate.

[0069] Mechanical properties tests were performed on Examples 2-5, Comparative Examples 2-5, and Comparative Example 6. The results are shown in the following table:

[0070]

[0071]

[0072] The experimental data in the table above show that structural regulation can significantly improve the mechanical properties of composite materials. The mechanical properties of all samples were greatly improved after orientation structure regulation. In Example 2, when the boron nitride content was 5 vol% and the orientation structure was regulated, the tensile strength reached 37.7 MPa and the impact strength reached 10.1 kJ / m 2 , can achieve strength similar to that of pure polybutylene succinate, which is beneficial to the practical application of the material.

[0073] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Other variations and modifications are possible without exceeding the technical solutions described in the claims.

Claims

1. A high thermal conductivity and electrically insulating polymer composite material having an oriented isolation dual filler network, characterized in that: The high thermal conductivity and electrically insulating polymer composite material having an oriented isolation dual filler network is prepared as follows: (1) melt-blending polybutylene succinate resin and multi-walled carbon nanotubes, crushing and sieving the resulting mixture to obtain a polybutylene succinate / carbon nanotube composite masterbatch with a particle size of 500 to 800 μm; the volume of the polybutylene succinate resin is 95 to 99.5% of the total volume of the polybutylene succinate resin and the multi-walled carbon nanotubes; (2) mechanically blending the polybutylene succinate / carbon nanotube composite masterbatch described in step (1) with boron nitride powder to obtain polybutylene succinate / carbon nanotube@boron nitride composite particles; the volume ratio of the polybutylene succinate / carbon nanotube composite masterbatch to the boron nitride powder is 100:5-20; (3) The polybutylene succinate / carbon nanotube@boron nitride composite particles described in step (1) are sequentially subjected to hot pressing, annealing, and cutting, and the resulting sample is subjected to orientation structure regulation in the length direction in a mold to obtain the high thermal conductivity and electrically insulating polymer composite material with an oriented isolation dual filler network; wherein the annealing temperature is 115-125°C, the pressure is 4.5-5.5 MPa, and the annealing time is 1.5-2 h; the processing temperature for the orientation structure regulation is 80-100°C, the pressure is 30-100 MPa, the width of the sample is equal to the groove width of the mold, and the ratio of the thickness of the sample to the high thermal conductivity and electrically insulating polymer composite material with an oriented isolation dual filler network is 1.8-2.5:

1.

2. The high thermal conductivity and electrically insulating polymer composite material having an oriented isolation dual filler network according to claim 1, wherein: The melt blending in step (1) is carried out in a torque rheometer.

3. The high thermal conductivity and electrically insulating polymer composite material having an oriented isolation dual filler network according to claim 1, wherein: The temperature of the melt blending in step (1) is 135-145° C., the mixing speed is 55-60 r / min, and the time is 4-5 min.

4. The high thermal conductivity and electrically insulating polymer composite material having an oriented isolation dual filler network according to claim 3, wherein: The melt blending in step (1) is carried out in a torque rheometer, with a melt blending temperature of 140° C., a mixing speed of 60 r / min, and a mixing time of 5 min.

5. The high thermal conductivity and electrically insulating polymer composite material having an oriented isolation dual filler network according to claim 1, wherein: The mechanical blending in step (2) is carried out in a high-speed mixer at a rotation speed of 18000-20000 r / min for 1.5-2.5 min.

6. The high thermal conductivity and electrically insulating polymer composite material having an oriented isolation dual filler network according to claim 1, wherein: The hot pressing molding in step (3) is carried out in a flat vulcanizer at a temperature of 135-145° C., a pressure of 8-10 MPa, and a time of 4.5-5.5 min.

7. The high thermal conductivity and electrically insulating polymer composite material having an oriented isolation dual filler network according to claim 6, wherein: The temperature of the hot pressing molding in step (3) is 140° C., the pressure is 10 MPa, and the time is 5 minutes.

8. The high thermal conductivity and electrically insulating polymer composite material having an oriented isolation dual filler network according to claim 1, wherein: The annealing temperature in step (3) is 120° C., the pressure is 5 MPa, and the annealing time is 2 h.

9. The high thermal conductivity and electrically insulating polymer composite material having an oriented isolation dual filler network according to claim 1, wherein: The orientation structure control in step (3) is carried out on a flat-plate vulcanizing machine at a processing temperature of 80° C. and a pressure of 100 MPa.

10. The high thermal conductivity and electrically insulating polymer composite material having an oriented isolation dual filler network according to claim 1, wherein: The thickness ratio of the sample to the high thermal conductivity and electrically insulating polymer composite material having an oriented isolation dual filler network is 2:1.

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