Ultra-high molecular weight polyethylene fiber self-reinforced crosslinked polyethylene material as well as preparation method and application thereof

Abstract

The invention provides an ultra-high molecular weight polyethylene fiber self-reinforced crosslinked polyethylene material as well as a preparation method and application thereof, and belongs to the field of high polymer materials. The preparation method comprises the following steps: respectively dipping polyethylene powder and ultra-high molecular weight polyethylene fibers in a cross-linking agent solution and a cross-linking aid solution to obtain pretreated polyethylene powder and pretreated ultra-high molecular weight polyethylene fibers, and mixing and hot-pressing the pretreated polyethylene powder and pretreated ultra-high molecular weight polyethylene fibers to obtain the self-reinforced polyethylene material. The co-crosslinking structure on the surface of the polyethylene fiber improves the interface bonding strength and crosslinking degree of the material, obviously improves the enhancement effect of the high-performance ultra-high molecular weight polyethylene fiber on the matrix, and realizes the self-enhancement of the polyethylene resin. The ultra-high molecular weight polyethylene fiber self-reinforced crosslinked polyethylene material provided by the invention is excellent in heat resistance and mechanical property, especially outstanding in thermal mechanical property, and provides technical support for high-temperature environment application of the polyethylene material.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials, specifically relating to a self-reinforced cross-linked polyethylene material made of ultra-high molecular weight polyethylene fiber, its preparation method, and its uses. Background Technology

[0002] Polyethylene (PE) is lightweight and has a high hydrogen content, making it a widely used matrix for neutron and gamma radiation shielding materials. However, the linear structure of PE causes its molecular chains to move easily at high temperatures, which greatly limits its application in high-temperature shielding environments. To improve the heat resistance and mechanical properties of materials, crosslinking, surface modification, and fiber reinforcement techniques are commonly used. Among these, fiber-reinforced materials, with their superior performance, have become one of the most widely used and fastest-growing categories of composite materials. Since the mechanical properties of composite materials largely depend on the interfacial interaction between the reinforcing fibers and the matrix, strengthening the interfacial bonding between the matrix and fibers has become a crucial scientific problem that urgently needs to be solved.

[0003] In recent years, self-reinforcing methods have proven to be an effective way to improve the interfacial properties of polymers. The concept of self-reinforcing composites (SRCs) was first proposed by Capiati and Porter in 1975. Currently, polypropylene-based SRC materials are commercially available, such as... Armordone, PURE, and others are mentioned. However, polyethylene-based SRC materials have not yet been commercialized. Compared with traditional composite materials, SRC has advantages including high compatibility between the matrix and reinforcement, good interfacial interaction, and high recyclability. Dilyus I. Chukov et al. prepared a novel UHMWPE fiber structure using a hot-pressing process, which significantly improved the material's friction coefficient. Hongtao Li et al. prepared SRC with different fiber contents and aspect ratios, finding that the composite material with a high aspect ratio fiber content of 50% had the lowest wear rate.

[0004] However, current research on the preparation of composite materials using self-reinforcing methods mainly focuses on room temperature properties, with little research on the changes in mechanical properties and thermal deformation under high-temperature conditions. Furthermore, there is a lack of research on introducing crosslinking agents into the interface of self-reinforcing materials to improve the interfacial properties through chemical crosslinking, thereby enhancing the thermomechanical properties and deformation resistance of the composite materials. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a self-reinforced cross-linked polyethylene material made of ultra-high molecular weight polyethylene fiber, its preparation method and its uses.

[0006] This invention provides a cross-linked polyethylene material, the preparation method of which includes the following steps:

[0007] (1) Immerse polyethylene fibers in a solution of crosslinking agent and crosslinking aid, remove them, and dry them to obtain pretreated polyethylene fibers;

[0008] (2) Mix the polyethylene matrix, crosslinking agent and crosslinking aid, add the pretreated polyethylene fiber obtained in step (1), mix, and mold to obtain crosslinked polyethylene material.

[0009] Furthermore, the polyethylene matrix is ​​polyethylene powder;

[0010] The crosslinking agent is a peroxide crosslinking agent;

[0011] The crosslinking aid is a crosslinking aid containing unsaturated bonds;

[0012] The polyethylene is one or a mixture of two or more of ultra-high molecular weight polyethylene, high-density polyethylene, low-density polyethylene, and linear low-density polyethylene.

[0013] Furthermore, the polyethylene matrix is ​​ultra-high molecular weight polyethylene powder; the polyethylene fiber is ultra-high molecular weight polyethylene fiber;

[0014] The crosslinking agent is one or a mixture of two or more of di-tert-butyl peroxide, dicumyl peroxide, benzoyl peroxide, and dicumyl hydroperoxide.

[0015] The crosslinking aid is one or a mixture of two or more of the following: trimethylolpropane trimethacrylate, triallyl isocyanurate, tricyanate, pentaerythritol triacrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, and propoxylated trimethylolpropane triacrylate.

[0016] Furthermore, the crosslinking agent is di-tert-butyl peroxide;

[0017] The crosslinking aid is trimethylolpropane trimethacrylate.

[0018] Further, in step (1), the solvent in the solution of the crosslinking agent and the crosslinking aid is an organic solvent, preferably acetone, dichloromethane or trichloromethane; the concentration of the crosslinking agent is 0.005 to 1 mol / L, preferably 0.01 mol / L, and the concentration of the crosslinking aid is 0.005 to 1 mol / L, preferably 0.01 mol / L.

[0019] Further, in step (2), the mass ratio of polyethylene matrix, crosslinking agent, crosslinking aid, and pretreated polyethylene fiber is 100-300:1:1:10-30, preferably 200:1:1:20.

[0020] The present invention also provides a method for preparing the above-mentioned cross-linked polyethylene material, the method comprising the following steps:

[0021] (1) Immerse polyethylene fibers in a solution of crosslinking agent and crosslinking aid, remove them, and dry them to obtain pretreated polyethylene fibers;

[0022] (2) Mix the polyethylene matrix, crosslinking agent and crosslinking aid, add the pretreated polyethylene fiber obtained in step (1), mix, and mold to obtain crosslinked polyethylene material.

[0023] Furthermore, in step (2), the molding method is hot pressing.

[0024] Further, in step (2), the temperature of the hot pressing is 130-160°C, the time is 5-30 min, and the pressure is 5-15 MPa;

[0025] Preferably, the hot pressing temperature is 145-155°C, the time is 20 min, and the pressure is 10 MPa.

[0026] The present invention also provides the use of the above-mentioned cross-linked polyethylene material in the preparation of high-temperature shielding materials.

[0027] This invention involves impregnating polyethylene powder and ultra-high molecular weight polyethylene (UHMWPE) fibers separately in solutions of a crosslinking agent and a crosslinking aid to obtain pretreated polyethylene powder and pretreated UHMWPE fibers. These are then mixed and hot-pressed to obtain a self-reinforced polyethylene material. The co-crosslinked structure on the surface of the polyethylene fibers enhances the interfacial bonding strength and crosslinking degree, significantly improving the reinforcing effect of the high-performance UHMWPE fibers on the matrix, thus achieving self-reinforcement of the polyethylene resin. The UHMWPE fiber self-reinforced crosslinked polyethylene material provided by this invention exhibits excellent heat resistance and mechanical properties, especially outstanding thermomechanical properties, providing technical support for the application of polyethylene materials in high-temperature environments. In higher-temperature radiation protection environments such as spent fuel storage ponds, this UHMWPE fiber self-reinforced crosslinked polyethylene material can extend the material's service life and reduce costs, supporting the safe and efficient development of nuclear energy resources.

[0028] Obviously, based on the above description of the present invention, and according to common technical knowledge and conventional methods in the field, various other modifications, substitutions or alterations can be made without departing from the basic technical concept of the present invention.

[0029] The following detailed embodiments further illustrate the above-described content of the present invention. However, this should not be construed as limiting the scope of the present invention to the following embodiments. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Attached Figure Description

[0030] Figure 1 The room temperature (a) tensile strength and (b) flexural strength of ultra-high molecular weight polyethylene fiber self-reinforced cross-linked polyethylene material are shown.

[0031] Figure 2 The Vicat softening point is the value of self-reinforced cross-linked polyethylene material made from ultra-high molecular weight polyethylene fibers. Detailed Implementation

[0032] The raw materials and equipment used in this invention are all known products, obtained by purchasing commercially available products.

[0033] The ultra-high molecular weight polyethylene (UHMWPE) powder used in this embodiment of the invention has a molecular weight of 3 million and a particle size of 120 μm; the UHMWPE chopped fibers have a molecular weight of 7 million, a fiber length of 6 mm, and a fiber diameter of 25 μm.

[0034] The "room temperature" referred to in this invention is 25±10℃.

[0035] Example 1: 10% Ultra-High Molecular Weight Polyethylene Fiber Self-Reinforced Cross-linked Polyethylene Material

[0036] The specific preparation process includes the following steps:

[0037] (1) Place the ultra-high molecular weight polyethylene fiber (UHMWPE) into a crosslinking solution with a concentration of 0.01 mol / L (the crosslinking solution contains 0.01 mol / L crosslinking agent di-tert-butyl peroxide (DTBP) and 0.01 mol / L crosslinking aid trimethylolpropane trimethacrylate (TMPTMA)), immerse for 2 hours, and then dry for later use;

[0038] (2) Weigh 80g of UHMWPE powder, put it into a mixer, add 0.4g of DTBP and 0.4g of TMPTMA and mix thoroughly;

[0039] (3) Add 8g of the above pretreated fiber and mix thoroughly in a mixer; add the mixture into a mold frame and plasticize for 20min at 10MPa and 155℃, then allow to cool naturally. The ultra-high molecular weight polyethylene fiber self-reinforced cross-linked polyethylene material (denoted as UHMWPE / D@T-10%F) is obtained.

[0040] Table 1. Formulation and Naming of UHMWPE Fiber Reinforced Crosslinked Polyethylene Sheets

[0041]

[0042] Example 2: Cross-linked polyethylene material

[0043] Referring to the method of Example 1, according to the formulation in Table 1, without adding UHMWPE fibers to the UHMWPE powder, a cross-linked polyethylene material with a UHMWPE fiber content of 0% (denoted as UHMWPE / D@T-0%F) was obtained.

[0044] Example 3: 5% Fiber Self-Reinforced Crosslinked Polyethylene Material

[0045] Referring to the method of Example 1, UHMWPE fibers were added to UHMWPE powder according to the formulation in Table 1 to obtain a self-reinforced cross-linked polyethylene material with a UHMWPE fiber content of 5% (denoted as UHMWPE / D@T-5%F).

[0046] Example 4: 20% Fiber Self-Reinforced Crosslinked Polyethylene Material

[0047] Referring to the method of Example 1, UHMWPE fibers were added to UHMWPE powder according to the formulation in Table 1 to obtain a self-reinforced cross-linked polyethylene material with a UHMWPE fiber content of 20% (denoted as UHMWPE / D@T-20%F).

[0048] Example 5: 100% Fiber Self-Reinforced Crosslinked Polyethylene Material

[0049] Referring to the method of Example 1, and according to the formulation in Table 1, without adding UHMWPE powder, a self-reinforced cross-linked polyethylene material with 100% UHMWPE fiber content (denoted as UHMWPE / D@T-100%F) was obtained.

[0050] The following describes the preparation of control samples using control examples.

[0051] Comparison with Example 1: Fiber-reinforced cross-linked polyethylene material

[0052] The specific preparation process includes the following steps: (1) Weigh 70g of PE matrix powder, then add 0.35g of DTBP and 0.35g of TMPTMA, and mix at high speed for 3min at room temperature; (2) Add 7g of UHMWPE fiber, and continue mixing for 2min; (3) Transfer to a mold frame for hot pressing, and plasticize at 10MPa and 155℃ for 20min, then cool naturally. Solvent-free fiber self-reinforced crosslinked polyethylene material is thus obtained.

[0053] The following experimental examples demonstrate the beneficial effects of the present invention.

[0054] Experiment Example 1: Testing the Mechanical Properties of Materials

[0055] 1. Experimental Methods

[0056] The plates obtained from the examples and comparative examples were cut using a cutting knife. The dimensions of the dumbbell-shaped spline were based on standard GB / T1040.2-2006 (Type 1BA), and the dimensions of the bending spline were based on standard GB / T9341-2008, for later use. Test conditions: tensile rate of 10 mm / min, bending rate of 5 mm / min, and test temperature of 30℃.

[0057] 2. Experimental Results

[0058] analyze Figure 1 It can be seen that the mechanical properties of the composite material are significantly improved with the increase of UHMWPE fiber content. When the UHMWPE fiber content is ≤20%, the tensile and flexural properties of cross-linked polyethylene improve relatively slowly. When the UHMWPE fiber content is 100%, the mechanical properties of the material are greatly improved, with a tensile strength of 57.6 MPa and a flexural strength of 43.6 MPa. This indicates that the introduction of fiber orientation structure improves the regularity of molecular chains, thereby improving tensile strength.

[0059] Vicat softening point of polyethylene crosslinked materials reinforced with different contents of UHMWPE fibers, such as Figure 2 As shown, the Vicat softening point increases significantly with the increase of UHMWPE fiber content, thus raising the upper limit of the material's service temperature. When the UHMWPE fiber content is ≥20%, the Vicat softening point of the self-reinforced material is >150℃. This is because UHMWPE fibers themselves have higher heat resistance than the polyethylene matrix, and therefore the orientation structure improves the heat resistance of the composite material.

[0060] In summary, this invention provides a self-reinforced cross-linked polyethylene material made of ultra-high molecular weight polyethylene (UHMWPE) fibers, its preparation method, and its applications. This invention involves impregnating polyethylene powder and UHMWPE fibers separately in solutions of a cross-linking agent and a cross-linking aid to obtain pretreated polyethylene powder and pretreated UHMWPE fibers. These are then mixed and hot-pressed to obtain the self-reinforced polyethylene material. The co-cross-linked structure on the surface of the polyethylene fibers enhances the interfacial bonding strength and cross-linking degree, significantly improving the reinforcing effect of the high-performance UHMWPE fibers on the matrix, thus achieving self-reinforcement of the polyethylene resin. The self-reinforced cross-linked polyethylene material made of UHMWPE fibers provided by this invention exhibits excellent heat resistance and mechanical properties, especially outstanding thermomechanical properties, providing technical support for the application of polyethylene materials in high-temperature environments.

Claims

1. A cross-linked polyethylene material, characterized in that, Its preparation method includes the following steps: (1) Immerse polyethylene fibers in a solution of crosslinking agent and crosslinking aid, remove them, and dry them to obtain pretreated polyethylene fibers; (2) Mix the polyethylene matrix, crosslinking agent and crosslinking aid, add the pretreated polyethylene fiber obtained in step (1), mix, and mold to obtain crosslinked polyethylene material.

2. The cross-linked polyethylene material according to claim 1, characterized in that, The polyethylene matrix is ​​polyethylene powder; The crosslinking agent is a peroxide crosslinking agent; The crosslinking aid is a crosslinking aid containing unsaturated bonds; The polyethylene is one or a mixture of two or more of ultra-high molecular weight polyethylene, high-density polyethylene, low-density polyethylene, and linear low-density polyethylene.

3. The cross-linked polyethylene material according to claim 2, characterized in that, The polyethylene matrix is ​​ultra-high molecular weight polyethylene powder; the polyethylene fiber is ultra-high molecular weight polyethylene fiber; The crosslinking agent is one or a mixture of two or more of di-tert-butyl peroxide, dicumyl peroxide, benzoyl peroxide, and dicumyl hydroperoxide. The crosslinking aid is one or a mixture of two or more of the following: trimethylolpropane trimethacrylate, triallyl isocyanurate, tricyanate, pentaerythritol triacrylate, trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, and propoxylated trimethylolpropane triacrylate.

4. The cross-linked polyethylene material according to claim 3, characterized in that, The crosslinking agent is di-tert-butyl peroxide; The crosslinking aid is trimethylolpropane trimethacrylate.

5. The cross-linked polyethylene material according to claim 1, characterized in that, In step (1), the solvent in the solution of the crosslinking agent and the crosslinking aid is an organic solvent, preferably acetone, dichloromethane or trichloromethane; the concentration of the crosslinking agent is 0.005 to 1 mol / L, preferably 0.01 mol / L, and the concentration of the crosslinking aid is 0.005 to 1 mol / L, preferably 0.01 mol / L.

6. The cross-linked polyethylene material according to claim 1, characterized in that, In step (2), the mass ratio of polyethylene matrix, crosslinking agent, crosslinking aid, and pretreated polyethylene fiber is 100-300:1:1:10-30, preferably 200:1:1:

20.

7. A method for preparing the cross-linked polyethylene material according to any one of claims 1-6, characterized in that, The method includes the following steps: (1) Immerse polyethylene fibers in a solution of crosslinking agent and crosslinking aid, remove them, and dry them to obtain pretreated polyethylene fibers; (2) Mix the polyethylene matrix, crosslinking agent and crosslinking aid, add the pretreated polyethylene fiber obtained in step (1), mix, and mold to obtain crosslinked polyethylene material.

8. The method according to claim 7, characterized in that, In step (2), the molding method is hot pressing.

9. The method according to claim 8, characterized in that, In step (2), the hot pressing temperature is 130-160℃, the time is 5-30 min, and the pressure is 5-15 MPa; Preferably, the hot pressing temperature is 145-155°C, the time is 20 min, and the pressure is 10 MPa.

10. Use of the cross-linked polyethylene material according to any one of claims 1-6 in the preparation of high-temperature shielding materials.

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