Composite material containing cross-linked polyethylene and graphene oxide, use and manufactring meyhod thereof

Abstract

The present disclosure provides a composite material containing cross-linked polyethylene and graphene oxide having excellent mechanical properties and heat dissipation at the same time by adding graphene oxide into cross-linked polyethylene and a use thereof, and a cable made from the composite material can have good safety and long lifespan.

Description

Technical Field

[0001] This invention relates to composite materials, particularly composite materials comprising cross-linked polyethylene (XLPE) and graphene oxide. Prior Technology

[0002] Cross-linked polyethylene (XLPE) is a polyethylene material modified through chemical or physical cross-linking, renowned for its excellent high-temperature resistance, chemical resistance, and mechanical strength. XLPE can be manufactured using methods such as extrusion molding and is widely used in products such as water supply pipes, medical equipment, and cables. XLPE is particularly prominent in high-voltage cables because it effectively resists the influence of internal electric fields and possesses good heat resistance and anti-aging properties, maintaining the structural stability of the insulation layer and thus significantly extending the cable's service life.

[0003] XLPE plays a vital role in cable manufacturing, particularly in high-voltage cables requiring high insulation, heat resistance, and deformation resistance. Furthermore, because the passage of current generates high temperatures in cables, their heat dissipation performance is crucial for extending their service life. Good heat dissipation helps prevent overheating and thermal damage, ensuring safe operation and allowing cables to carry larger currents, thus enabling smaller wire diameters for greater flexibility. Therefore, achieving the optimal balance between mechanical properties and heat dissipation is a critical issue in cable-related fields. Summary of the Invention

[0004] This invention provides a composite material and its use in manufacturing cables, by adding graphene oxide to cross-linked polyethylene to achieve the advantages of both excellent mechanical properties and heat dissipation, and the cables made therefrom have good safety, heat dissipation, flexibility and long service life.

[0005] To achieve the above objectives, the present invention provides a composite material comprising cross-linked polyethylene and graphene oxide, wherein the weight ratio of cross-linked polyethylene to graphene oxide is 9:1 to 7:3.

[0006] In a composite material according to one embodiment of the present invention, the weight ratio of cross-linked polyethylene to graphene oxide is 8:2 to 7:3.

[0007] In a composite material according to one embodiment of the present invention, the weight ratio of cross-linked polyethylene to graphene oxide is 7:3.

[0008] In a composite material according to one embodiment of the present invention, graphene oxide is modified with carboxylic acid groups and hydroxyl groups.

[0009] In a composite material according to one embodiment of the present invention, the weight-average molecular weight of cross-linked polyethylene can be between 6,000 and 300,000.

[0010] In a composite material according to one embodiment of the present invention, the tensile strength measured according to ASTM D638 is greater than or equal to 10 megapascals (MPa).

[0011] In a composite material according to one embodiment of the present invention, the elongation measured according to ASTM D638 is greater than or equal to 200%.

[0012] In one embodiment of the composite material of the present invention, the withstanding voltage measured according to ASTM D149 is greater than or equal to 2.0 kV.

[0013] On the other hand, the present invention also provides the use of a composite material comprising cross-linked polyethylene and graphene oxide for manufacturing cables.

[0014] On the other hand, the present invention also provides a method for manufacturing a heat dissipation composite material for cables, comprising: modifying graphene oxide with a silane coupling agent containing carboxylic acid groups and hydroxyl groups, and then mixing cross-linked polyethylene in a weight ratio of 9:1 to 7:3 with the modified graphene oxide using a twin-screw extruder to produce a heat dissipation composite material for cables.

[0015] The effects of the present invention are not limited to those mentioned above, and those skilled in the art to which this invention pertains will clearly understand from the following description the effects not mentioned above. Simple Explanation of the Diagram

[0016] none. Implementation

[0017] The following embodiments describe in detail the features and advantages of the present invention, the content of which is sufficient to enable anyone skilled in the art to understand the technical content of the present invention and implement it accordingly. Furthermore, based on the disclosure, patent claims, and drawings in this specification, anyone skilled in the art can easily understand the relevant objectives and advantages of the present invention. The following embodiments further illustrate the points of the present invention, but are not intended to limit the scope of the present invention in any way.

[0018] This invention provides a composite material comprising cross-linked polyethylene (XLPE) and graphene oxide, wherein the weight ratio of XLPE to graphene oxide is 9:1 to 7:3. The graphene oxide is dispersed in the XLPE matrix.

[0019] In one embodiment of the composite material of the present invention, the weight ratio of cross-linked polyethylene to graphene oxide is 8:2 to 7:3. In another embodiment of the composite material of the present invention, the weight ratio of cross-linked polyethylene to graphene oxide is 7:3.

[0020] In one embodiment of the composite material of the present invention, the cross-linked polyethylene used has a weight-average molecular weight of 6,000 to 300,000. In another embodiment of the composite material of the present invention, the graphene oxide used is carboxylic acid and hydroxyl-modified graphene oxide, designated E-PG, with a particle size less than 1 nm and an oxygen content ≤20% by weight (wt%). By modifying the graphene oxide with carboxylic acid and hydroxyl groups, the dispersibility, adhesion, and compatibility of the modified graphene oxide in the cross-linked polyethylene are improved.

[0021] The preparation, testing, and test results of composite materials according to several embodiments of the present invention are described below.

[0022] Preparation method: Graphene oxide was modified with a silane coupling agent containing carboxylic acid groups and hydroxyl groups. Then, the modified graphene oxide and XLPE were mixed in different ratios (as shown in Table 1) to form a composite material using a twin-screw extruder. Samples were then made by injection molding or extrusion molding.

[0023] The property testing method is as follows:

[0024] 1. Tensile strength, elongation, and Young's modulus: These were determined according to ASTM D638 TYPE IV. Following this procedure, a dog-bone shaped sample with a total length of 165 mm, a thickness of 3.2 mm (1 / 8 inch), and a gauge length of 50 mm (2 inches) was fixed between two clamps at room temperature. The sample was stretched at a rate of 50 mm / min until fracture, and the tensile strength and elongation were recorded. The Young's modulus was calculated from the tensile force and the amount of deformation of the sample.

[0025] 2. Hardness: A dog bone-shaped sample measuring 2 inches × 2 inches and with a minimum thickness of 6.4 mm (0.25 inches) was used to determine the hardness using a Shore D hardness tester according to ASTM D2240.

[0026] 3. Surface resistivity: Measured according to ASTM D257. Following this procedure, a sample measuring 10cm × 10cm × 2mm is connected to two electrodes, a voltage is applied, and the current flowing through the sample is recorded. The surface resistivity is calculated from the measured voltage and current.

[0027] 4. Withstand Voltage Test: The test is performed according to ASTM D149. Following this procedure, a 10cm × 10cm × 2mm sample is connected to two electrodes. Leakage current is recorded at different voltages, and a voltage is applied until dielectric breakdown occurs. The voltage at the breakdown point is recorded (i.e., withstand voltage).

[0028] 5. Thermal conductivity: Determined according to ISO 22007-2 (Instantaneous planar heat source (hot plate) method). According to this procedure, a disc-shaped heat source is placed in the center of a 10cm × 10cm × 4.5mm sample, and the heat source is heated. The thermal conductivity of the sample is calculated by measuring the temperature change of the hot plate over time.

[0029] 6. Cooling efficiency: A 10cm×10cm×4mm sample was heated for 600 seconds using a 0.46W heater, and the sample temperature was recorded. The cooling efficiency of each sample was calculated using Equation 1 based on the measured temperature. Equation 1: Cooling efficiency = (Example temperature - Comparative example temperature) / Comparative example temperature × 100%.

[0030] Aging resistance test: According to ASTM D412, the sample was placed in an oven at 110°C and subjected to a constant temperature of 110°C with air exchange 8 to 20 times. After 168 hours, the physical properties of the sample were tested.

[0031] Table 1 below reveals the composition of pure XLPE (Comparative Example 1) and XLPE / graphene oxide composite materials (Examples 1-5) and the results of their property tests before and after aging.

[0032] Table 1 Comparative example (Pure XLPE) Example 1 Example 2 Example 3 Example 4 Example 5 Graphene oxide (wt%) 0 10 15 20 27.5 30 XLPE (wt%) 100 90 85 80 72.5 70 Tensile strength (MPa) 13.384 21.316 19.451 16.967 12.1 11.18 Tensile strength after aging (MPa) 13.34 20.001 19.08 16.519 10.6 11.651 Elongation (%) 425.409 734.604 881.053 383.728 340 318.02 Elongation after aging (%) 401.55 585.021 709.828 275.078 252 216.558 Young's modulus (MPa) 54.845 24.286 26.775 78.814 - 80.114 Young's modulus (MPa) after aging 51.11 23.727 29.76 75.547 - 99.29 Hardness (D) 41 43 46 47 47 46 Hardness (D) after aging 40 46 45 49 - 44 Surface resistivity (Ω / sq) 1.65 * 10^12 2.15 * 10^12 1.96*10^12 2.51*10^12 2.25 * 10^12 1.89*10^12 Withstand voltage (kV) - 5 5 5 - 5 Thermal conductivity (W / mK) 0.3 - - - - 1.0 Cooling efficiency (%) - 5.6 9.7 12.9 - 21.3

[0033] As shown in Table 1, compared to pure XLPE without graphene oxide (comparative example), XLPE with graphene oxide (Examples 1-5) exhibits superior cooling efficiency while maintaining good mechanical properties. The "good mechanical properties" include a tensile strength greater than or equal to 10 MPa and an elongation greater than or equal to 200%.

[0034] The composite material of this invention exhibits excellent aging resistance, maintaining its physical properties and appearance even after prolonged exposure to high temperatures and oxidation. This characteristic contributes to the long-term reliability of the cable and provides it with good safety and a long lifespan.

[0035] In summary, the composite material provided by this invention achieves the advantages of both excellent mechanical properties and heat dissipation by adding graphene oxide to cross-linked polyethylene. Furthermore, cables manufactured from this composite material exhibit good safety, heat dissipation, flexibility, and long service life.

[0036] While the present invention has been disclosed above with reference to the foregoing embodiments, it is not intended to limit the invention. Any modifications and refinements made without departing from the spirit and scope of the invention are within the scope of patent protection of the present invention. For details regarding the scope of protection defined in the present invention, please refer to the appended claims.

[0037] none.

Claims

1. A composite material comprising: cross-linked polyethylene (XLPE); and graphene oxide; wherein, The weight ratio of cross-linked polyethylene to graphene oxide is 7:3; the weight average molecular weight of cross-linked polyethylene is 6,000 to 300,000; the graphene oxide is modified with carboxylic acid groups and hydroxyl groups and has an oxygen content of ≤20% by weight; the tensile strength measured according to ASTM D638 is greater than or equal to 10 MPa; the elongation measured according to ASTM D638 is greater than or equal to 200%; and the withstanding voltage measured according to ASTM D149 is greater than or equal to 2.0 kV.

2. Use of a composite material as described in claim 1 for manufacturing a cable.

3. A method for manufacturing a composite material as claimed in claim 1, comprising: modifying graphene oxide with a silane coupling agent containing carboxylic acid groups and hydroxyl groups, and then mixing cross-linked polyethylene and the modified graphene oxide in a weight ratio of 7:3 using a twin-screw extruder to produce a heat dissipation composite material for cables, wherein the weight average molecular weight of the cross-linked polyethylene is 6,000 to 300,000; and the oxygen content of the graphene oxide is ≤20% by weight.