A nylon composite material suitable for high humidity environments and its preparation method
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHEJIANG YULONG TECH DEV
- Filing Date
- 2025-06-25
- Publication Date
- 2026-07-03
AI Technical Summary
The tensile strength of nylon composites decreases in high humidity environments, mainly due to the water absorption of the nylon 6 matrix and the weakening of the interfacial bonding between the glass fiber and PA6, which leads to a reduction in the load-bearing capacity of the composites in humid environments.
A composite of nickel-doped silicon carbide fiber and polyethylene glycol with nylon 6 matrix is formed. Through the strengthening of the interfacial bonding between nickel-doped silicon carbide fiber and nylon 6 and the improvement of polyethylene glycol dispersion, a dense β-crystalline structure is formed, which blocks the diffusion path of water molecules and enhances the interfacial bonding strength.
It significantly improves the tensile strength retention of nylon composites in high humidity environments, with a tensile strength loss rate of less than 3.9%.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of composite material technology, and in particular relates to a nylon composite material suitable for high humidity environments and its preparation method. Background Technology
[0002] Nylon composites suitable for high-humidity environments are engineering plastics with polyamide (PA) as the matrix and glass fiber (GF) as the reinforcing phase. For example, adding glass fiber to nylon 6 forms a nylon composite suitable for high-humidity environments. The addition of glass fiber can significantly improve the strength and rigidity of the material. Glass fiber reinforcement can also increase the heat distortion temperature, allowing the material to maintain structural stability at high temperatures. It is widely used in automobiles, electrical appliances, power tools and other fields.
[0003] The nylon 6 matrix has a high water absorption rate, while glass fiber itself does not absorb water. The addition of glass fiber reduces the overall water absorption rate of the composite material due to the adjustment of its volume ratio, thereby improving the reliability of the composite material in humid environments. However, the hygroscopic nature of the nylon 6 matrix itself remains unchanged. When the composite material is used in high humidity environments, moisture can still penetrate through the amide bonds of the nylon molecular chains, weakening the interfacial bonding between the glass fiber and PA6, thus reducing the tensile properties / tensile strength of the composite material and weakening its load-bearing capacity. Summary of the Invention
[0004] To address the aforementioned problems, this invention proposes a nylon composite material suitable for high humidity environments and its preparation method, which significantly improves the tensile strength retention of the composite material in high humidity environments.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0006] A nylon composite material suitable for high humidity environments, comprising the following components by weight: 64-67 parts nylon 6, 26-28 parts glass fiber, 3-4 parts nickel-doped silicon carbide fiber, 0.5-0.7 parts polyethylene glycol, 2-3 parts compatibilizer, 0.2-0.5 parts antioxidant, and 0.2-0.5 parts lubricant.
[0007] Preferably, the preparation method of the nickel-doped silicon carbide fiber is as follows: 95-100g of polycarbosilane is dissolved in 200-220mL of xylene, and then 2-2.5g of nano-nickel particles are added and ultrasonically dispersed to obtain a mixture; under vacuum conditions, the mixture is distilled to remove xylene to obtain nano-nickel-polycarbosilane; the nano-nickel-polycarbosilane is melt-spun, non-melting treated and sintered to obtain nickel-doped silicon carbide fiber.
[0008] Preferably, the ultrasonic dispersion frequency is 30-40kHz and the ultrasonic dispersion time is 40-60min.
[0009] Preferably, the distillation process is carried out at a temperature of 90-105°C for 50-80 minutes and a vacuum degree of -0.08 MPa.
[0010] Preferably, the melt spinning temperature is 280-320℃, the melt spinning pressure is 0.5-1.2MPa, and the melt spinning speed is 0.5-2.0mL / min.
[0011] Preferably, the non-melting treatment is carried out at a constant temperature of 200-220°C.
[0012] Preferably, the sintering process is as follows: in a nitrogen atmosphere, the temperature is increased to 1200-1250°C at a rate of 5°C / min, held for 100-120 min, and then cooled to room temperature at a rate of 3-5°C / min.
[0013] Preferably, the compatibilizer includes any one or a mixture of at least two of maleic anhydride-grafted POE, maleic anhydride-grafted polyethylene, and maleic anhydride-grafted EPDM rubber; the antioxidant includes antioxidant 245 and / or antioxidant 1010; and the lubricant is calcium stearate.
[0014] A method for preparing a nylon composite material suitable for high humidity environments includes the following steps:
[0015] Step 1: Add nylon 6, glass fiber, nickel-doped silicon carbide fiber, polyethylene glycol, compatibilizer, antioxidant and lubricant to a high-speed mixer and mix to obtain a mixture;
[0016] Step 2: Add the mixture into a twin-screw extruder, melt-blend, extrude and granulate to obtain the nylon composite material suitable for high humidity environments.
[0017] Preferably, the melt extrusion temperature of the twin-screw extruder is 220-270℃, and the screw speed is 210-320 r / min.
[0018] Compared with the prior art, the present invention has the following beneficial effects:
[0019] The present invention relates to the preparation of nylon composite materials applicable to high humidity environments. In addition to the base material nylon 6 and the reinforcing material glass fiber, the raw materials also include nickel-doped silicon carbide fiber and polyethylene glycol. The two can produce a synergistic effect in the glass fiber reinforced nylon 6 system, synergistically reducing the hygroscopicity of the obtained composite material, and thus synergistically enhancing the tensile strength retention ability of the composite material in high humidity environments.
[0020] Specifically, in the preparation of nickel-doped silicon carbide fibers, nickel forms active sites through surface doping, which coordinate or covalently bond with the terminal amino or carboxylic acid groups of nylon 6, strengthening the interfacial bonding strength, reducing water absorption channels caused by interfacial defects, and thus reducing the hygroscopicity of the composite material. Polyethylene glycol reduces the agglomeration tendency of nickel-doped silicon carbide fibers through molecular chain entanglement and polar adsorption, improves the dispersion of nickel-doped silicon carbide fibers in the nylon 6 matrix, and effectively avoids local stress concentration and interfacial weakening caused by agglomeration of nickel-doped silicon carbide fibers. The interfacial bonding of nickel-doped silicon carbide fibers and the dispersion improvement of polyethylene glycol have a synergistic effect, synergistically reducing interfacial water absorption channels, and thus synergistically reducing the hygroscopicity of the composite material.
[0021] On the other hand, the high surface roughness of nickel-doped silicon carbide fibers and the metallic properties of nickel can act as heterogeneous nucleating agents for nylon 6, promoting the formation of β-crystals. Although the β-crystal itself has a higher water absorption rate than the α-crystal, polyethylene glycol and nickel-doped silicon carbide fibers synergistically induce nylon 6 to form a "dense β-crystal surface layer - tough amorphous inner layer" structure. This structure is constructed by utilizing the difference in free volume at the interface between the crystalline and amorphous regions and the crystal gradient. By physically blocking / inhibiting the diffusion path of water molecules, it achieves the effect of synergistically reducing the hygroscopicity of the composite material and synergistically enhancing the tensile strength retention of the composite material in high humidity environments. Detailed Implementation
[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0023] Example 1
[0024] A method for preparing a nylon composite material suitable for high humidity environments includes the following steps:
[0025] Step 1: According to the weight proportions, first add 65 parts of nylon 6, 27 parts of glass fiber and 3.5 parts of nickel-doped silicon carbide fiber to a high-speed mixer and mix at 300 rpm for 1 minute; then add 0.6 parts of polyethylene glycol, 2.5 parts of compatibilizer, 0.3 parts of antioxidant and 0.3 parts of lubricant, and mix at 450 rpm for 3 minutes to obtain the mixture.
[0026] The following materials were purchased: Nylon 6 (Lanxess B30S food grade, Germany) from Shanghai Unis Plastics Technology Co., Ltd.; Alkali-free glass fiber (3mm, Grade A) from Lingshou Shuolong Mineral Products Processing Plant; Polyethylene glycol (PEG-4000) from Jiangsu Haian Petrochemical Plant; Compatibilizer maleic anhydride-grafted POE (Dow POE-g-MAH, USA) from Dongguan Shangpin New Materials Technology Co., Ltd.; Antioxidant 1010 (superior grade) from Dongguan Dinghai Plastics & Chemical Co., Ltd.; and Lubricant calcium stearate (superior grade) from Dongguan Shanyi Plastics Co., Ltd.
[0027] Step 2: Set the melt extrusion temperature of the twin-screw extruder to 220-270℃ and the screw speed to 300r / min. Add the mixture into the twin-screw extruder, melt blend, and extrude granulate to obtain a nylon composite material suitable for high humidity environments.
[0028] The specific temperature settings for the nine zones of the twin-screw extruder from the feeding section to the die head are as follows: 220℃, 230℃, 245℃, 260℃, 270℃, 270℃, 250℃, 230℃, and 220℃.
[0029] The preparation method of nickel-doped silicon carbide fiber is as follows: 98g of polycarbosilane was dissolved in 210mL of xylene, followed by the addition of 2.2g of nano-nickel particles. The mixture was then ultrasonically dispersed at 35kHz for 50min to obtain a mixture. The mixture was then distilled at approximately 95℃ under a vacuum of -0.08MPa for 60 minutes to remove xylene, yielding nano-nickel-polycarbosilane. The nano-nickel-polycarbosilane was first melt-spun at approximately 310℃, with a melting temperature of approximately 0.7MPa and a melting speed of approximately 1.5mL / min. It was then subjected to a non-melting treatment; placed in an air-circulating furnace with an oxygen concentration slightly higher than 20%, the cross-linking efficiency was ensured by real-time monitoring of the oxygen content. The temperature was increased from room temperature to 210℃ at a rate of 2℃ / min to avoid sudden stress changes on the fiber surface that could lead to cracking. The temperature was maintained for 3 hours to allow oxidation of the fiber surface, forming a cross-linked structure and preventing melt deformation during subsequent sintering. Re-sintering treatment: Maintain the nitrogen flow rate in the sintering furnace at about 8L / min to ensure timely discharge of pyrolysis byproducts. Specifically, in a nitrogen atmosphere (purity ≥99.999%), heat to 1230℃ at 5℃ / min and hold for 110min to optimize the fiber structure. Then, slowly cool to room temperature at a rate of 4℃ / min (hold at about 900℃ for 10 minutes to relieve crystal phase transformation stress) to obtain nickel-doped silicon carbide fiber.
[0030] Polycarbosilane (molecular weight 1000-1800) was purchased from Forsmann Technology (Beijing) Co., Ltd. Nickel nanoparticles (purity ≥99.9%, average particle size 50nm) were purchased from Yunyan New Materials (Shanghai) Co., Ltd.
[0031] Example 2
[0032] The difference between this embodiment and Embodiment 1 is that: a method for preparing a nylon composite material suitable for high humidity environments includes the following steps:
[0033] Step 1: According to the weight proportions, first add 64 parts of nylon 6, 26 parts of glass fiber and 3 parts of nickel-doped silicon carbide fiber to a high-speed mixer and mix at 300 rpm for 1 minute; then add 0.5 parts of polyethylene glycol, 2 parts of compatibilizer, 0.2 parts of antioxidant and 0.2 parts of lubricant, and mix at 450 rpm for 3 minutes to obtain the mixture.
[0034] Step 2: Set the melt extrusion temperature of the twin-screw extruder to 220-270℃ and the screw speed to 300r / min. Add the mixture into the twin-screw extruder, melt blend, and extrude granulate to obtain a nylon composite material suitable for high humidity environments.
[0035] Example 3
[0036] The difference between this embodiment and Embodiment 1 is that: a method for preparing a nylon composite material suitable for high humidity environments includes the following steps:
[0037] Step 1: By weight, first add 67 parts of nylon 6, 28 parts of glass fiber and 4 parts of nickel-doped silicon carbide fiber to a high-speed mixer and mix at 300 rpm for 1 minute; then add 0.7 parts of polyethylene glycol, 3 parts of compatibilizer, 0.5 parts of antioxidant and 0.5 parts of lubricant, and mix at 450 rpm for 3 minutes to obtain the mixture.
[0038] Step 2: Set the melt extrusion temperature of the twin-screw extruder to 220-270℃ and the screw speed to 300r / min. Add the mixture into the twin-screw extruder, melt blend, and extrude granulate to obtain a nylon composite material suitable for high humidity environments.
[0039] Comparative Example 1
[0040] The only difference between this comparative example and Example 1 is that the nickel-doped silicon carbide fiber is replaced with glass fiber, and polyethylene glycol is removed.
[0041] Specifically, a method for preparing a nylon composite material suitable for high-humidity environments includes the following steps:
[0042] Step 1: According to the weight proportions, first add 65 parts of nylon 6 and 30.5 parts of glass fiber to a high-speed mixer and mix at a speed of 300 rpm for 1 minute; then add 2.5 parts of compatibilizer, 0.3 parts of antioxidant and 0.3 parts of lubricant, and mix at a speed of 450 rpm for 3 minutes to obtain the mixture.
[0043] Step 2: Set the melt extrusion temperature of the twin-screw extruder to 220-270℃ and the screw speed to 300r / min. Add the mixture into the twin-screw extruder, melt blend, and extrude granulate to obtain a nylon composite material suitable for high humidity environments.
[0044] Comparative Example 2
[0045] The only difference between this comparative example and Example 1 is that the nickel-doped silicon carbide fiber is replaced with glass fiber.
[0046] Specifically, a method for preparing a nylon composite material suitable for high-humidity environments includes the following steps:
[0047] Step 1: According to the weight proportions, first add 65 parts of nylon 6 and 30.5 parts of glass fiber to a high-speed mixer and mix at a speed of 300 rpm for 1 minute; then add 0.6 parts of polyethylene glycol, 2.5 parts of compatibilizer, 0.3 parts of antioxidant and 0.3 parts of lubricant, and mix at a speed of 450 rpm for 3 minutes to obtain the mixture.
[0048] Step 2: Set the melt extrusion temperature of the twin-screw extruder to 220-270℃ and the screw speed to 300r / min. Add the mixture into the twin-screw extruder, melt blend, and extrude granulate to obtain a nylon composite material suitable for high humidity environments.
[0049] Comparative Example 3
[0050] The only difference between this comparative example and Example 1 is the removal of polyethylene glycol.
[0051] Specifically, a method for preparing a nylon composite material suitable for high-humidity environments includes the following steps:
[0052] Step 1: According to the weight proportions, first add 65 parts of nylon 6, 27 parts of glass fiber and 3.5 parts of nickel-doped silicon carbide fiber to a high-speed mixer and mix at a speed of 300 rpm for 1 minute; then add 2.5 parts of compatibilizer, 0.3 parts of antioxidant and 0.3 parts of lubricant, and mix at a speed of 450 rpm for 3 minutes to obtain the mixture.
[0053] Step 2: Set the melt extrusion temperature of the twin-screw extruder to 220-270℃ and the screw speed to 300r / min. Add the mixture into the twin-screw extruder, melt blend, and extrude granulate to obtain a nylon composite material suitable for high humidity environments.
[0054] Experimental Example: ① The tensile strength σ0 of nylon composite material specimens suitable for high humidity environments was obtained by testing Examples 1-3 and Comparative Examples 1-3 according to GB / T1040-92. ② Each specimen was immersed in deionized water at 40±2℃ for 48 hours, then removed and dried, and the tensile strength σ1 after immersion was tested. ③ The tensile strength loss rate Rσ was calculated; the calculation formula is: Rσ=(σ0-σ1) / σ0×100%; the smaller the value of Rσ, the stronger the tensile strength retention ability of the corresponding specimen in a high humidity environment.
[0055] Experimental results: see Table 1.
[0056] Table 1. Statistical Analysis of Experimental Results for Each Experimental Example
[0057] Tensile strength σ0 (MPa) Tensile strength σ1 (MPa) after immersion in water Tensile strength loss rate Rσ (%) Example 1 187.5 180.4 3.8 Example 2 186.2 179.5 3.6 Example 3 187.9 180.6 3.9 Comparative Example 1 168.4 159.6 5.2 Comparative Example 2 166.7 154.9 7.1 Comparative Example 3 185.8 177.6 4.4
[0058] Results Analysis: Analysis of Examples 1-3 based on the data in Table 1 shows that the tensile strength of the nylon composite material prepared by this invention, suitable for high humidity environments, is as high as 186.2 MPa or more, and the tensile strength loss rate after immersion in deionized water at 40±2℃ for 48 hours is as low as 3.9%. This indicates that the nylon composite material prepared by this invention has excellent tensile strength suitable for high humidity environments and excellent tensile property retention in such environments.
[0059] Based on the data in Table 1, the analysis of Example 1 and Comparative Examples 1-3 shows that when the reinforcing material is a single glass fiber, the addition of polyethylene glycol will weaken the tensile strength retention of the nylon composite material suitable for high humidity environments.
[0060] This is because polyethylene glycol, as a polar substance, interferes with the regular arrangement of nylon 6 molecular chains, inhibits the formation of α-crystals, and leads to an increase in the proportion of amorphous regions in the composite material, increasing the free volume of molecular chains and providing diffusion channels and adsorption sites for water molecules. Furthermore, polyethylene glycol has limited compatibility with the nylon 6 matrix and glass fibers, which can easily induce phase separation and form interfacial microcracks or pores, further expanding the water penetration path and thus weakening the tensile strength retention of the composite material in high humidity environments.
[0061] By comparing Comparative Example 3 and Example 1, it can be seen that the introduction of nickel-doped silicon carbide fibers can enhance the tensile strength retention of the nylon composite material suitable for high humidity environments. On this basis, the addition of polyethylene glycol can produce a synergistic effect, which can synergistically enhance the tensile strength retention of the composite material in high humidity environments.
[0062] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A nylon composite material suitable for high humidity environments, characterized in that: By weight, it includes the following components: 64-67 parts nylon 6, 26-28 parts glass fiber, 3-4 parts nickel-doped silicon carbide fiber, 0.5-0.7 parts polyethylene glycol, 2-3 parts compatibilizer, 0.2-0.5 parts antioxidant and 0.2-0.5 parts lubricant; The preparation method of the nickel-doped silicon carbide fiber is as follows: 95-100g of polycarbosilane is dissolved in 200-220mL of xylene, and then 2-2.5g of nano-nickel particles are added and ultrasonically dispersed to obtain a mixture; under vacuum conditions, the mixture is distilled to obtain nano-nickel-polycarbosilane; the nano-nickel-polycarbosilane is melt-spun, non-melting treated and sintered to obtain nickel-doped silicon carbide fiber.
2. The nylon composite material suitable for high humidity environments according to claim 1, characterized in that: The ultrasonic dispersion frequency is 30-40kHz, and the ultrasonic dispersion time is 40-60min.
3. The nylon composite material suitable for high humidity environments according to claim 1, characterized in that: The distillation process is carried out at a temperature of 90-105℃ for 50-80 minutes and a vacuum degree of -0.08MPa.
4. The nylon composite material suitable for high humidity environments according to claim 1, characterized in that: The melt spinning temperature is 280-320℃, the melt spinning pressure is 0.5-1.2MPa, and the melt spinning speed is 0.5-2.0mL / min.
5. The nylon composite material suitable for high humidity environments according to claim 1, characterized in that: The non-melting treatment is carried out at a constant temperature of 200-220℃.
6. The nylon composite material suitable for high humidity environments according to claim 1, characterized in that: The specific operation of the sintering process is as follows: in a nitrogen atmosphere, the temperature is raised to 1200-1250℃ at a rate of 5℃ / min, held for 100-120min, and then cooled to room temperature at a rate of 3-5℃ / min.
7. The nylon composite material suitable for high humidity environments according to claim 1, characterized in that: The compatibilizer includes any one or a mixture of at least two of maleic anhydride-grafted POE, maleic anhydride-grafted polyethylene, and maleic anhydride-grafted EPDM rubber; the antioxidant includes antioxidant 245 and / or antioxidant 1010; and the lubricant is calcium stearate.
8. A method for preparing a nylon composite material suitable for high humidity environments as described in any one of claims 1-7, characterized in that: Includes the following steps: Step 1: Add nylon 6, glass fiber, nickel-doped silicon carbide fiber, polyethylene glycol, compatibilizer, antioxidant and lubricant to a high-speed mixer and mix to obtain a mixture; Step 2: Add the mixture to a twin-screw extruder, melt-blend, extrude and granulate to obtain the nylon composite material suitable for high humidity environments.
9. The method for preparing nylon composite materials suitable for high humidity environments according to claim 8, characterized in that: The melt extrusion temperature of the twin-screw extruder is 220-270℃, and the screw speed is 210-320 r / min.