Aerospace powder toughening material forming particle size directional regulation method

Abstract

The application relates to a method for directional regulation of the molding particle size of powder toughening materials for aviation, which comprises the following steps: adding different masses of polyvinyl alcohol corresponding to different particle sizes of powder toughening materials into water, stirring and dissolving to prepare polyvinyl alcohol solutions with different mass concentrations; adding thermoplastic plastic into an organic solvent, stirring and dissolving to obtain a first solution; adding the polyvinyl alcohol solutions with different mass concentrations into the first solution respectively, stirring and dissolving to obtain second solutions corresponding to the different particle sizes of the powder toughening materials respectively; and carrying out post-treatment on the second solutions to obtain powder toughening materials with different particle sizes; wherein the mass concentration of the polyvinyl alcohol solution is 1-10 wt%, and the volume average particle size of the obtained powder toughening materials is 4-60 mu m. The molding particle size of the powder toughening materials is directionally regulated by changing the mass concentration of the polyvinyl alcohol solution, and the adjusting method is simple and easy to realize.

Description

Technical Field

[0001] This application relates to the field of polymer powder materials technology, and in particular to a method for directional control of the particle size of a powder toughening material for aerospace applications. Background Technology

[0002] Fiber-reinforced polymers (FRPs) are composite materials made from fiber-reinforced polymer matrices. They have high specific strength and specific modulus, as well as excellent corrosion resistance and fatigue resistance. They are widely used in manufacturing fields that require tensile and compressive stress, such as aircraft structural components, wind turbine blades, and worm gears.

[0003] Currently, the demand for polymer materials with toughening properties in high-end application fields such as aerospace is becoming increasingly apparent. In order to improve the mechanical properties of fiber-reinforced polymers, in addition to adding fiber materials to the resin, some functional additives are also added, such as toughening materials. These toughening materials are prepared using thermoplastic materials such as polyamide and polyethersulfone as matrix materials, and their appearance is a white powder.

[0004] Currently, the research and development of such powder toughening materials is lagging behind, making it difficult to meet the high-performance requirements of downstream applications. Domestic research in this area lacks a systematic, well-defined, and mature material forming process and methods for controlling key indicators of the forming process. Therefore, it is necessary to propose a method for the directional control of particle size in the forming of powder toughening materials for aerospace applications. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a method for directional control of the particle size of powder toughening materials for aerospace applications, which enables directional adjustment of the particle size of powder toughening materials.

[0006] According to the first aspect of this application, a method for directional control of the particle size of a powder toughening material for aerospace applications is provided, comprising the following steps:

[0007] Different masses of polyvinyl alcohol, each corresponding to a different particle size of powder toughening material, were added to water, stirred and dissolved, and then polyvinyl alcohol solutions of different mass concentrations were prepared.

[0008] The thermoplastic is added to an organic solvent and stirred until dissolved to obtain the first solution;

[0009] Different mass concentrations of the polyvinyl alcohol solution were added to the first solution, and the mixture was stirred to dissolve, resulting in a second solution that corresponds to a variety of powder toughening materials with different particle sizes.

[0010] After post-processing, each of the second solutions yielded powder toughening materials with different particle sizes;

[0011] When the mass concentration of the polyvinyl alcohol solution is 1-10 wt%, the volume average particle size of the obtained powder toughening material is 4-60 μm.

[0012] In some embodiments of this application, when the mass concentration of the polyvinyl alcohol solution is 2-4 wt%, the volume average particle size of the obtained powder toughening material is 30-55 μm;

[0013] When the mass concentration of the polyvinyl alcohol solution is 4-5 wt%, the volume average particle size of the obtained powder toughening material is 15-30 μm.

[0014] When the mass concentration of the polyvinyl alcohol solution is 5-8 wt%, the volume average particle size of the obtained powder toughening material is 7-15 μm.

[0015] In some embodiments of this application, the mass ratio of the thermoplastic to the polyvinyl alcohol solution is 1:8 to 1:9.5.

[0016] In some embodiments of this application, the mass ratio of the thermoplastic to the polyvinyl alcohol solution is 1:8 to 1:8.5.

[0017] In some embodiments of this application, when preparing the first solution, the dissolution temperature is 38-48℃, the stirring speed is 40-80rpm, and the dissolution time is 8-15h.

[0018] In some embodiments of this application, when preparing the first solution, the dissolution temperature is 40-45℃, the stirring speed is 60-80rpm, and the dissolution time is 10-12h.

[0019] In some embodiments of this application, the stirring speed is 150-400 rpm when preparing the second solution.

[0020] In some embodiments of this application, the stirring speed is 200-350 rpm when preparing the second solution.

[0021] In some embodiments of this application, the organic solvent is a single organic solvent or a complex organic solvent;

[0022] The single organic solvent includes N-methyl-2-pyrrolidone;

[0023] The composite organic solvent consists of 15-40 wt% methanol and 60-85 wt% chloroform.

[0024] In some embodiments of this application, the content of the thermoplastic in the first solution is 5-15 wt%.

[0025] Compared with the prior art, the technical solution provided by this application can include the following beneficial effects: This application can directionally control the molding particle size of the powder toughening material by changing the mass concentration of the polyvinyl alcohol solution, and the adjustment method is simple and easy to implement.

[0026] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be arbitrarily combined with each other.

[0028] Fiber-reinforced polymers (FRPs) are composite materials made from fiber-reinforced polymer matrices. They have high specific strength and specific modulus, as well as excellent corrosion resistance and fatigue resistance. They are widely used in manufacturing fields that require tensile and compressive stress, such as aircraft structural components, wind turbine blades, and worm gears.

[0029] Currently, the demand for polymer materials with toughening properties in high-end application fields such as aerospace is becoming increasingly apparent. In order to improve the mechanical properties of fiber-reinforced polymers, in addition to adding fiber materials to the resin, some functional additives are also added, such as toughening materials. These toughening materials are made by using thermoplastic materials such as polyamide, polyethersulfone, polyurethane, polycarbonate, and polyimide as matrix materials and carbon fiber as reinforcement materials. They have a significant effect on improving the impact resistance, high temperature and high humidity resistance, and interlaminar toughness of the products.

[0030] However, the application technology of toughening materials in aerospace composite materials is still immature and difficult to meet the standards for aerospace materials. To address this, the inventors developed a toughening agent suitable for high-end carbon fiber applications such as aerospace. Chinese invention patent application CN115850890A describes this toughening agent and discloses its preparation method. Prepregs made with this toughening agent exhibit significant advantages in post-impact compressive strength and Type I fracture toughness. To further improve product quality, the inventors, based on the aforementioned patent application, conducted more in-depth research on how to directionally control the particle size of the powder toughening material.

[0031] Based on this, this application provides a method for directional control of the particle size of powder toughening materials for aerospace applications. This method is used to prepare powder toughening materials with various particle sizes. Different masses of polyvinyl alcohol (PVA), corresponding one-to-one with the different particle sizes of the powder toughening materials, are added to water to prepare PVA solutions of different mass concentrations. PVA solutions of different mass concentrations are then added to a first solution prepared from thermoplastic plastics and organic solvents to obtain powder toughening materials with different particle sizes. This application compares the conditions in the material synthesis process of powder toughening materials and observes the change in the volume average particle size of the molded product. Combined with the requirements of aerospace-grade prepregs, the mass concentration of the PVA solution is used as a key particle size indicator for directional control of the product, thereby improving the process control level and quality control capability of the powder toughening material molding stage. This application controls the particle size of the powder toughening material by adjusting the mass concentration of the PVA solution; the adjustment method is simple and easy to implement.

[0032] In an exemplary embodiment of this application, this embodiment provides a method for directional control of the particle size of powder toughening materials for aerospace applications, used to prepare powder toughening materials with various particle sizes, including the following steps:

[0033] S1. Add different masses of polyvinyl alcohol, each corresponding to a different particle size of powder toughening material, to water, stir and dissolve to prepare polyvinyl alcohol solutions of different mass concentrations.

[0034] S2. Add thermoplastic plastic to an organic solvent, stir to dissolve, and obtain the first solution;

[0035] S3. Add polyvinyl alcohol solutions of different mass concentrations to the first solution, stir and dissolve to obtain second solutions that correspond one-to-one with various powder toughening materials of different particle sizes.

[0036] S4. After post-processing each of the second solutions, powder toughening materials with different particle sizes are obtained;

[0037] The polyvinyl alcohol solution has a mass concentration of 1-10 wt%, and the resulting powder toughening material has a volume average particle size of 4-60 μm.

[0038] In this application, the organic solvent serves only as a solvent medium and does not participate in the chemical reaction itself. It acts as a carrier for dissolving, dispersing, and supporting the thermoplastic plastic. The selection of the organic solvent needs to be determined in conjunction with the thermodynamic stability state and thermodynamic functions of the thermoplastic plastic (polymer material). Typical polymer solutions are macromolecular dispersion systems, which are true solutions in a thermodynamically stable state. The dissolution of polymer materials involves swelling followed by dissolution. Due to the large size of the macromolecular chains in polymer materials, the diffusion and unfolding abilities between molecules are low. Furthermore, the macromolecular chains are entangled before dissolution, resulting in significant intermolecular interactions. Therefore, the dissolution process is relatively slow, often requiring several hours or even days. The dissolution process generally involves the preferential penetration of smaller solvent molecules, weakening the intermolecular forces and causing the polymer material to expand in volume. Subsequently, the movement of chain segments and the entire molecular chain accelerates, leading to chain loosening and deentanglement. Finally, uniform bidirectional diffusion completes the dissolution of the polymer material.

[0039] In step S2, polyvinyl alcohol (PVA), as a surfactant, contains both hydrophilic and lipophilic groups. A PVA solution is added to the first solution to initiate an emulsification reaction. The essence of this emulsification process is the physical mixing of the surfactant component with the dissolved polymer matrix. Microscopically, this can be understood as the directional movement and bonding between PVA macromolecules and the macromolecules of the polymer material. This directional bonding is based on the bonding characteristics of the hydrophilic-lipophilic groups with the dissolved polymer material, adhering to the qualitative and qualitative determination of the hydrophilic and lipophilic groups in the reaction system. Therefore, by controlling specific temperatures, stirring speeds, and times, the emulsification process can form a uniformly mixed and stable solution.

[0040] In this application, the polyvinyl alcohol solution plays a role in controlling and maintaining the formed particle size. When the polyvinyl alcohol solution is added to the first solution of this application, the lipophilic groups on the polyvinyl alcohol molecular chains bind to the surface of the oil-phase thermoplastic polymer, while the hydrophilic groups are on the outside, forming a three-dimensional spherical hydrophilic group. Thus, even under subsequent stirring, the dissolved polymer droplets will not be compatible due to the mutual repulsion of the hydrophilic groups, thereby achieving particle size control and maintaining it until the particle size formation stage. Therefore, the polyvinyl alcohol solution plays an important role in the particle size formation stage. This application controls the formed particle size of micron-sized powder materials by adjusting the mass concentration of the surfactant added to the reaction system.

[0041] The type of thermoplastic used in this application is not limited; any non-crystalline thermoplastic suitable for powder toughening materials may be used, such as polyamide, polyimide, polycarbonate, etc.

[0042] For example, the general structural formula of polyamide is shown in formula (I):

[0043]

[0044] R1 is a benzene ring with its two ends connected at the meta position; R2 is 11 chain alkanes.

[0045] For example, the general structural formula of polycarbonate is shown in formula (II):

[0046]

[0047] In one embodiment, when the mass concentration of the polyvinyl alcohol solution is 2-4 wt%, the volume average particle size of the obtained powder toughening material is 30-55 μm;

[0048] When the mass concentration of the polyvinyl alcohol solution is 4-5 wt%, the volume average particle size of the obtained powder toughening material is 15-30 μm.

[0049] When the mass concentration of the polyvinyl alcohol solution is 5-8 wt%, the volume average particle size of the obtained powder toughening material is 7-15 μm.

[0050] This application, through research and development experiments, has determined the relationship between the mass concentration of polyvinyl alcohol solution and the volume average particle size of powder toughening material, which enables directional adjustment of the molding particle size of powder toughening material.

[0051] In one embodiment, the degree of alcoholysis of polyvinyl alcohol is 85-90% (mol / mol).

[0052] The degree of hydrolysis refers to the percentage of hydroxyl groups in the product obtained after hydrolysis compared to the original functional groups. In this embodiment, a polyvinyl alcohol with a degree of hydrolysis of 85-90% (mol / mol) is selected, which is a partially hydrolyzed polyvinyl alcohol and is soluble in water at room temperature. The CAS number of the polyvinyl alcohol in this application is CAS.9002-89-5. For example, the polyvinyl alcohol can be selected as polyvinyl alcohol 1788, with a degree of hydrolysis of 87.0-89.0% (mol / mol); or it can be selected as polyvinyl alcohol 2488, with a degree of hydrolysis of 87.0-89.0% (mol / mol).

[0053] In one embodiment, the mass ratio of thermoplastic to polyvinyl alcohol solution is 1:8 to 1:9.5.

[0054] In this embodiment, when controlling the directional size of the powder toughening material, in addition to adjusting the mass concentration of polyvinyl alcohol, the mass concentration of thermoplastic plastic and polyvinyl alcohol solution is also adjusted. When the mass ratio of thermoplastic plastic to polyvinyl alcohol solution is 1:8 to 1:9.5, the powder toughening material has better molding stability by adjusting the mass concentration of polyvinyl alcohol solution.

[0055] In one embodiment, the mass ratio of thermoplastic to polyvinyl alcohol solution is 1:8 to 1:8.5.

[0056] For example, the mass ratio of thermoplastic to polyvinyl alcohol solution is 1:8. Of course, it is understood that the mass ratio of thermoplastic to polyvinyl alcohol solution can also be other ratios within the above range, such as 1:8.2, 1:8.5, 1:9 or 1:9.5.

[0057] In one embodiment, when preparing the first solution, the dissolution temperature is 38-48°C, the stirring speed is 40-80 rpm, and the dissolution time is 8-15 h.

[0058] In one embodiment, when preparing the first solution, the dissolution temperature is 40-45°C, the stirring speed is 60-80 rpm, and the dissolution time is 10-12 h.

[0059] For example, when preparing the first solution, the dissolution temperature is 38°C, the stirring speed is 40 rpm, and the stirring time is 15 h. Of course, it is understood that when preparing the first solution, the dissolution temperature, stirring speed, and stirring time can also be other values ​​within the above range. For example, when preparing the first solution, the dissolution temperature is 40°C, the stirring speed is 60 rpm, and the stirring time is 12 h; when preparing the first solution, the dissolution temperature is 45°C, the stirring speed is 70 rpm, and the stirring time is 10 h; when preparing the first solution, the dissolution temperature is 48°C, the stirring speed is 80 rpm, and the stirring time is 8 h.

[0060] In one embodiment, the stirring speed is 150-400 rpm when preparing the second solution.

[0061] The particle size of the powder toughening material in this application is mainly related to the mass concentration of the polyvinyl alcohol solution. By adjusting the mass concentration of the polyvinyl alcohol solution, the distribution range of the particle size of the powder toughening material can be controlled. The particle size can be finely adjusted by adjusting the rotation speed during the emulsification reaction, so that micron-sized powder toughening materials with a predetermined target size can be obtained.

[0062] In one embodiment, the stirring speed is 200-350 rpm when preparing the second solution.

[0063] For example, the stirring speed is 150 rpm when preparing the second solution. Of course, it is understood that the stirring speed when preparing the second solution can also be other speeds within the above range, such as 200 rpm, 350 rpm, or 400 rpm.

[0064] In one embodiment, when preparing the second solution, the polyvinyl alcohol solution is added dropwise over 25-50 minutes; preferably, the polyvinyl alcohol solution is added dropwise over 35-45 minutes.

[0065] To ensure a complete reaction between the polyvinyl alcohol (PVA) solution and the first solution, the PVA solution in this embodiment needs to be added dropwise to the first solution. The volume of PVA solution added within one minute can be used as a control indicator for the reaction, or the overall dropping time of the PVA solution can be used as a control indicator for the dropping rate. For example, in this embodiment, the overall dropping time of the PVA solution is used as the control indicator for the reaction. For instance, when preparing the second solution, the PVA solution is added dropwise within 25 minutes. Of course, it is understood that the overall dropping time of the PVA solution can also be other times within the above range, such as adding the PVA solution dropwise within 35 minutes, 45 minutes, or 50 minutes.

[0066] In one embodiment, the organic solvent is a single organic solvent or a complex organic solvent;

[0067] Single organic solvents include N-methyl-2-pyrrolidone;

[0068] The composite organic solvent consists of 15-40 wt% methanol and 60-85 wt% chloroform.

[0069] The organic solvent in this application serves as a solvent for thermoplastic plastics, acting as a carrier for dissolving, dispersing, and supporting them. Different proportions of methanol and chloroform have different dispersion effects on thermoplastic plastics. When the composite organic solvent consists of 15-40 wt% methanol and 60-85 wt% chloroform, it exhibits excellent solubility and dispersibility for thermoplastic plastics.

[0070] Furthermore, the composite organic solvent consists of 20-35 wt% methanol and 65-80 wt% chloroform.

[0071] For example, the composite organic solvent consists of 15 wt% methanol and 85 wt% chloroform; of course, it is understood that the methanol and chloroform in the composite organic solvent can also be in other proportions within the above range, for example, the composite organic solvent consists of 20 wt% methanol and 80 wt% chloroform; the composite organic solvent can consist of 35 wt% methanol and 65 wt% chloroform; or the composite organic solvent can also consist of 40 wt% methanol and 60 wt% chloroform.

[0072] In one embodiment, the content of thermoplastic in the first solution is 5-15 wt%.

[0073] Furthermore, the thermoplastic content in the first solution is 6-11 wt%.

[0074] For example, the content of thermoplastic in the first solution is 5 wt%. Of course, it is understood that the content of thermoplastic in the first solution can also be other contents within the above range, for example, the content of thermoplastic in the first solution is 6 wt%, 8 wt%, 11 wt%, or 15 wt%.

[0075] In one embodiment, the post-processing in step S4 includes the following steps: the second solution is subjected to vacuum distillation at a temperature of 20-50°C, a pressure of -0.06-0.098 MPa, and a distillation time of 4-8 hours to obtain a slurry mixture; the slurry mixture is washed with water, classified, and then subjected to particle size classification, and washed and diluted with a small amount of hot water to obtain a sieved intermediate; the sieved intermediate is sieved, centrifuged, and dried to obtain a white micron-sized powder material free of clusters and foreign matter.

[0076] In this embodiment, most of the organic solvent in the system can be removed by vacuum distillation to obtain a slurry mixture. The slurry mixture mainly includes the target product (powder toughening material) and a small amount of water and polyvinyl alcohol. At this time, washing with water can remove excess polyvinyl alcohol, which is beneficial to improving the purity of the finished product. Then, the particle size is classified to remove powders with excessively large particle sizes (e.g., powders with particle sizes > 60 μm) and excessively small particle sizes (e.g., powders with particle sizes < 4 μm), and retain powders with intermediate particle sizes (e.g., powders with particle sizes of 4-60 μm), which is the sieving intermediate. After sieving, centrifuging and drying, the sieving intermediate can be used to obtain white micron-sized powder material without agglomerates and foreign matter.

[0077] The following describes the specific implementation of this application in conjunction with preferred embodiments, and explains in detail the preferred value ranges of each component in the method for directional control of the particle size of toughening materials for aerospace applications provided by this application.

[0078] Preferred Example 1

[0079] A method for directional control of the particle size of a powder toughening material for aerospace applications, comprising the following steps:

[0080] Different masses of polyvinyl alcohol, each corresponding to a different particle size of powder toughening material, were added to water, stirred and dissolved, and then polyvinyl alcohol solutions of different mass concentrations were prepared.

[0081] The thermoplastic is added to an organic solvent and stirred until dissolved to obtain the first solution;

[0082] Different mass concentrations of polyvinyl alcohol solution were added to the first solution and stirred to dissolve, resulting in second solutions that corresponded one-to-one with various powder toughening materials of different particle sizes.

[0083] After post-processing, each second solution yielded powder toughening materials with different particle sizes.

[0084] When the mass concentration of the polyvinyl alcohol solution is 1-10 wt%, the volume average particle size of the obtained powder toughening material is 7-60 μm.

[0085] Preferred Example 2

[0086] Different masses of polyvinyl alcohol, each corresponding to a different particle size of powder toughening material, were added to water, stirred and dissolved, and then polyvinyl alcohol solutions of different mass concentrations were prepared.

[0087] The thermoplastic is added to an organic solvent and stirred until dissolved to obtain the first solution;

[0088] Different mass concentrations of polyvinyl alcohol solution were added to the first solution and stirred to dissolve, resulting in second solutions that corresponded one-to-one with various powder toughening materials of different particle sizes.

[0089] After post-processing, each second solution yielded powder toughening materials with different particle sizes.

[0090] When the mass concentration of the polyvinyl alcohol solution is 2-4 wt%, the volume average particle size of the obtained powder toughening material is 30-55 μm.

[0091] When the mass concentration of the polyvinyl alcohol solution is 4-5 wt%, the volume average particle size of the obtained powder toughening material is 15-30 μm.

[0092] When the mass concentration of the polyvinyl alcohol solution is 5-8 wt%, the volume average particle size of the obtained powder toughening material is 7-15 μm.

[0093] Preferred Example 3

[0094] Different masses of polyvinyl alcohol, each corresponding to a different particle size of powder toughening material, were added to water, stirred and dissolved, and then polyvinyl alcohol solutions of different mass concentrations were prepared.

[0095] The thermoplastic is added to an organic solvent and stirred until dissolved to obtain the first solution;

[0096] Different mass concentrations of polyvinyl alcohol solution were added to the first solution and stirred to dissolve, resulting in second solutions that corresponded one-to-one with various powder toughening materials of different particle sizes.

[0097] After post-processing, each second solution yielded powder toughening materials with different particle sizes.

[0098] When the mass concentration of the polyvinyl alcohol solution is 1.05-2.01 wt%, the volume average particle size of the obtained powder toughening material is 45-60 μm.

[0099] When the mass concentration of the polyvinyl alcohol solution is 2.01-3.25 wt%, the volume average particle size of the obtained powder toughening material is 35-55 μm.

[0100] When the mass concentration of the polyvinyl alcohol solution is 3.26-4.01 wt%, the volume average particle size of the obtained powder toughening material is 30-45 μm.

[0101] When the mass concentration of the polyvinyl alcohol solution is 4.02-5.10 wt%, the volume average particle size of the obtained powder toughening material is 15-30 μm.

[0102] When the mass concentration of the polyvinyl alcohol solution is 5.11-6.20 wt%, the volume average particle size of the obtained powder toughening material is 12-15 μm.

[0103] When the mass concentration of the polyvinyl alcohol solution is 6.21-7.02 wt%, the volume average particle size of the obtained powder toughening material is 8-13 μm.

[0104] When the mass concentration of the polyvinyl alcohol solution is 7.03-8.16 wt%, the volume average particle size of the obtained powder toughening material is 7-10 μm.

[0105] When the mass concentration of the polyvinyl alcohol solution is 8.17wt-9.98%, the volume average particle size of the obtained powder toughening material is 4-7μm.

[0106] Preferred Example 3

[0107] Different masses of polyvinyl alcohol, each corresponding to a different particle size of powder toughening material, were added to water, stirred and dissolved, and then polyvinyl alcohol solutions of different mass concentrations were prepared.

[0108] The thermoplastic is added to an organic solvent and stirred until dissolved to obtain the first solution;

[0109] Different mass concentrations of polyvinyl alcohol solution were added to the first solution and stirred to dissolve, resulting in second solutions that corresponded one-to-one with various powder toughening materials of different particle sizes.

[0110] After post-processing, each second solution yielded powder toughening materials with different particle sizes.

[0111] When the mass concentration of the polyvinyl alcohol solution is 2-4 wt%, the volume average particle size of the obtained powder toughening material is 30-55 μm.

[0112] When the mass concentration of the polyvinyl alcohol solution is 4-5 wt%, the volume average particle size of the obtained powder toughening material is 15-30 μm.

[0113] When the mass concentration of the polyvinyl alcohol solution is 5-8 wt%, the volume average particle size of the obtained powder toughening material is 7-15 μm.

[0114] The mass ratio of thermoplastic to polyvinyl alcohol solution is 1:8 to 1:9.5.

[0115] Preferred Example 4

[0116] Different masses of polyvinyl alcohol, each corresponding to a different particle size of powder toughening material, were added to water, stirred and dissolved, and then polyvinyl alcohol solutions of different mass concentrations were prepared.

[0117] The thermoplastic is added to an organic solvent and stirred until dissolved to obtain the first solution;

[0118] Different mass concentrations of polyvinyl alcohol solution were added to the first solution and stirred to dissolve, resulting in second solutions that corresponded one-to-one with various powder toughening materials of different particle sizes.

[0119] After post-processing, each second solution yielded powder toughening materials with different particle sizes.

[0120] When the mass concentration of the polyvinyl alcohol solution is 2-4 wt%, the volume average particle size of the obtained powder toughening material is 30-55 μm.

[0121] When the mass concentration of the polyvinyl alcohol solution is 4-5 wt%, the volume average particle size of the obtained powder toughening material is 15-30 μm.

[0122] When the mass concentration of the polyvinyl alcohol solution is 5-8 wt%, the volume average particle size of the obtained powder toughening material is 7-15 μm.

[0123] The mass ratio of thermoplastic to polyvinyl alcohol solution is 1:8 to 1:8.5.

[0124] Preferred Example 5

[0125] Different masses of polyvinyl alcohol, each corresponding to a different particle size of powder toughening material, were added to water, stirred and dissolved, and then polyvinyl alcohol solutions of different mass concentrations were prepared.

[0126] The thermoplastic is added to an organic solvent and stirred until dissolved to obtain the first solution;

[0127] Different mass concentrations of polyvinyl alcohol solution were added to the first solution and stirred to dissolve, resulting in second solutions that corresponded one-to-one with various powder toughening materials of different particle sizes.

[0128] After post-processing, each second solution yielded powder toughening materials with different particle sizes.

[0129] When the mass concentration of the polyvinyl alcohol solution is 2-4 wt%, the volume average particle size of the obtained powder toughening material is 30-55 μm.

[0130] When the mass concentration of the polyvinyl alcohol solution is 4-5 wt%, the volume average particle size of the obtained powder toughening material is 15-30 μm.

[0131] When the mass concentration of the polyvinyl alcohol solution is 5-8 wt%, the volume average particle size of the obtained powder toughening material is 7-15 μm.

[0132] The mass ratio of thermoplastic to polyvinyl alcohol solution is 1:8.2 to 1:8.5.

[0133] Preferred Example Six

[0134] Different masses of polyvinyl alcohol, each corresponding to a different particle size of powder toughening material, were added to water, stirred and dissolved, and then polyvinyl alcohol solutions of different mass concentrations were prepared.

[0135] The thermoplastic is added to an organic solvent and stirred until dissolved to obtain the first solution;

[0136] Different mass concentrations of polyvinyl alcohol solution were added to the first solution and stirred to dissolve, resulting in second solutions that corresponded one-to-one with various powder toughening materials of different particle sizes.

[0137] After post-processing, each second solution yielded powder toughening materials with different particle sizes.

[0138] When the mass concentration of the polyvinyl alcohol solution is 2-4 wt%, the volume average particle size of the obtained powder toughening material is 30-55 μm.

[0139] When the mass concentration of the polyvinyl alcohol solution is 4-5 wt%, the volume average particle size of the obtained powder toughening material is 15-30 μm.

[0140] When the mass concentration of the polyvinyl alcohol solution is 5-8 wt%, the volume average particle size of the obtained powder toughening material is 7-15 μm.

[0141] The mass ratio of thermoplastic plastic to polyvinyl alcohol solution is 1:8 to 1:9.5;

[0142] When preparing the second solution, the stirring speed is 150-400 rpm.

[0143] Preferred Example 7

[0144] Different masses of polyvinyl alcohol, each corresponding to a different particle size of powder toughening material, were added to water, stirred and dissolved, and then polyvinyl alcohol solutions of different mass concentrations were prepared.

[0145] The thermoplastic is added to an organic solvent and stirred until dissolved to obtain the first solution;

[0146] Different mass concentrations of polyvinyl alcohol solution were added to the first solution and stirred to dissolve, resulting in second solutions that corresponded one-to-one with various powder toughening materials of different particle sizes.

[0147] After post-processing, each second solution yielded powder toughening materials with different particle sizes.

[0148] When the mass concentration of the polyvinyl alcohol solution is 2-4 wt%, the volume average particle size of the obtained powder toughening material is 30-55 μm.

[0149] When the mass concentration of the polyvinyl alcohol solution is 4-5 wt%, the volume average particle size of the obtained powder toughening material is 15-30 μm.

[0150] When the mass concentration of the polyvinyl alcohol solution is 5-8 wt%, the volume average particle size of the obtained powder toughening material is 7-15 μm.

[0151] The mass ratio of thermoplastic plastic to polyvinyl alcohol solution is 1:8 to 1:8.5;

[0152] When preparing the second solution, the stirring speed is 200-350 rpm.

[0153] To more clearly explain the technical solution of this application, this application provides specific embodiments of a method for directional control of the particle size of powder toughening materials for aerospace applications. The beneficial effects of selecting the above-mentioned ranges of component content and process parameters will be illustrated by specific experimental data provided through specific embodiments. It should be noted that the raw material components, contents, and process parameters of the embodiments of this application do not constitute a limitation on the scope of protection of this application.

[0154] It should be noted that the thermoplastics in the following examples are selected from polyamides as shown in formula (I) or polycarbonates as shown in formula (II), and the raw material composition of the polyvinyl alcohol solution is shown in Table 1.

[0155] Example

[0156] Example 1: A method for directional control of particle size in aerospace powder toughening materials, comprising the following steps:

[0157] (1) Add polyvinyl alcohol and water into a container, heat the container to 80°C in a water bath and stir for 12 hours to make the polyvinyl alcohol fully dissolve in the water until it is clear to the naked eye, and prepare a polyvinyl alcohol solution with a mass concentration of 2wt%.

[0158] (2) Add 21 kg of chloroform and 8 kg of methanol to the reactor, heat to 30°C and stir until homogeneous; then add 2.1 kg of thermoplastic plastic (polyamide) to the reactor, and stir continuously at 45 rpm for 12 h at 42°C to obtain a homogeneous and semi-transparent first solution; fill the reactor with nitrogen to replace 99% of the air and other gaseous components in the reactor with nitrogen.

[0159] (3) Slowly and uniformly add 18 kg of 2 wt% polyvinyl alcohol solution to the first solution in step (2) for 45 min, and keep the stirring speed at 200 rpm to obtain a uniform milky white second solution.

[0160] (4) The second solution was distilled under reduced pressure for 6 hours at a temperature of 20℃ and a pressure of -0.06MPa to obtain a slurry mixture;

[0161] (5) After washing and classifying the slurry mixture with water, the particle size is classified and then rinsed and diluted with a small amount of hot water to obtain a sieve intermediate. The sieve intermediate is sieved to screen the powder within the target particle size range. After centrifuging and drying the powder, 1.87 kg of powder toughening material can be obtained. The powder toughening material is a white micron-sized powder material without agglomerates or foreign matter.

[0162] Example 2: A method for directional control of particle size in the molding of aerospace powder toughening materials, comprising the following steps:

[0163] (1) Add polyvinyl alcohol and water into a container, heat the container to 80°C in a water bath and stir for 12 hours to make the polyvinyl alcohol fully dissolve in the water until it is clear to the naked eye, and prepare a polyvinyl alcohol solution with a mass concentration of 4wt%.

[0164] (2) Add 21 kg of chloroform and 8 kg of methanol to the reactor, heat to 30°C and stir until homogeneous; then add 2.1 kg of thermoplastic plastic (polyamide) to the reactor, and stir continuously at 45 rpm for 12 h at 42°C to obtain a homogeneous and semi-transparent first solution; fill the reactor with nitrogen to replace 99% of the air and other gaseous components in the reactor with nitrogen.

[0165] (3) Slowly and uniformly add 18 kg of 4 wt% polyvinyl alcohol solution to the first solution in step (2) for 45 min, and keep the stirring speed at 200 rpm to obtain a uniform milky white second solution.

[0166] (4) The second solution was distilled under reduced pressure for 6 hours at a temperature of 20℃ and a pressure of -0.06MPa to obtain a slurry mixture;

[0167] (5) After washing and classifying the slurry mixture with water, the particle size is classified and then rinsed and diluted with a small amount of hot water to obtain a sieve intermediate. The sieve intermediate is sieved to screen out powder within the particle size range. After centrifuging and drying the powder, 1.95 kg of powder toughening material can be obtained. The powder toughening material is a white micron-sized powder material without agglomerates or foreign matter.

[0168] Example 3: A method for directional control of particle size in the molding of aerospace powder toughening materials, comprising the following steps:

[0169] (1) Add polyvinyl alcohol and water into a container, heat the container to 80°C in a water bath and stir for 12 hours to make the polyvinyl alcohol fully dissolve in the water until it is clear to the naked eye, and prepare a polyvinyl alcohol solution with a mass concentration of 6wt%.

[0170] (2) Add 22 kg of chloroform and 7 kg of methanol to the reactor, heat to 30°C and stir until homogeneous; then add 2.1 kg of thermoplastic plastic (polyamide) to the reactor, and stir continuously at 45 rpm for 12 h at 42°C to obtain a homogeneous and semi-transparent first solution; then fill the reactor with nitrogen to replace 99% of the air and other gaseous components in the reactor with nitrogen.

[0171] (3) Slowly and uniformly add 18 kg of 6 wt% polyvinyl alcohol solution to the first solution in step (2) for 35 min, while maintaining a stirring speed of 280 rpm to obtain a uniform milky white second solution.

[0172] (4) The second solution was distilled under reduced pressure for 6 hours at a temperature of 20℃ and a pressure of -0.06MPa to obtain a slurry mixture;

[0173] (5) After washing and classifying the slurry mixture with water, the particle size is classified and then rinsed and diluted with a small amount of hot water to obtain a sieve intermediate. The sieve intermediate is sieved to screen the powder within the target particle size range. After centrifuging and drying the powder, 1.78 kg of powder toughening material can be obtained. The powder toughening material is a white micron-sized powder material without agglomerates or foreign matter.

[0174] Example 4: A method for directional control of particle size in the molding of aerospace powder toughening materials, comprising the following steps:

[0175] (1) Add polyvinyl alcohol and water into a container, heat the container to 80°C in a water bath and stir for 12 hours to make the polyvinyl alcohol fully dissolve in the water until it is clear to the naked eye, and prepare a polyvinyl alcohol solution with a mass concentration of 8wt%.

[0176] (2) Add 21 kg of chloroform and 8 kg of methanol to the reactor, heat to 30°C and stir until homogeneous; then add 2.1 kg of thermoplastic plastic (polyamide) to the reactor, and stir continuously at 45 rpm for 12 h at 42°C to obtain a homogeneous and semi-transparent first solution; fill the reactor with nitrogen to replace 99% of the air and other gaseous components in the reactor with nitrogen.

[0177] (3) Slowly and uniformly add 18 kg of 8 wt% polyvinyl alcohol solution to the first solution in step (2) for 40 min, and keep the stirring speed at 300 rpm to obtain a uniform milky white second solution.

[0178] (4) The second solution was distilled under reduced pressure for 6 hours at a temperature of 20℃ and a pressure of -0.06MPa to obtain a slurry mixture;

[0179] (5) After washing and classifying the slurry mixture with water, the particle size is classified and then rinsed and diluted with a small amount of hot water to obtain a sieve intermediate. The sieve intermediate is sieved to screen the powder within the target particle size range. After centrifuging and drying the powder, 1.85 kg of powder toughening material can be obtained. The powder toughening material is a white micron-sized powder material without agglomerates or foreign matter.

[0180] Example 5: A method for directional control of the particle size of aerospace powder toughening material, comprising the following steps:

[0181] (1) Add polyvinyl alcohol and water into a container, heat the container to 80°C in a water bath and stir for 12 hours to make the polyvinyl alcohol fully dissolve in the water until it is clear to the naked eye, and prepare a polyvinyl alcohol solution with a mass concentration of 5wt%.

[0182] (2) Weigh 42 kg of organic solvent (N-methyl-2-pyrrolidone) and add it to the reactor. Heat it to 78°C and stir until homogeneous. Then add 2.4 kg of thermoplastic resin (polycarbonate) to the heated organic solvent and stir continuously at 45 rpm for 10 h to obtain a homogeneous and translucent first solution. Purge the reactor with nitrogen to replace 99% of the air and other gaseous components in the reactor with nitrogen.

[0183] (3) Cool the first solution to 25°C, and slowly and uniformly add 40 kg of 5 wt% polyvinyl alcohol solution to the first solution for 45 min, while maintaining a stirring speed of 200 rpm to obtain a uniform milky white second solution.

[0184] (4) The second solution was distilled under reduced pressure for 6 hours at a temperature of 160℃ and a pressure of -0.06MPa to obtain a slurry mixture;

[0185] (5) After washing and classifying the slurry mixture with water, the particle size is classified and then rinsed and diluted with a small amount of hot water to obtain a sieve intermediate. The sieve intermediate is sieved to screen the powder within the target particle size range. After centrifuging and drying the powder, 1.80 kg of powder toughening material can be obtained. The powder toughening material is a white micron-sized powder material without agglomerates or foreign matter.

[0186] Table 1. Ingredients of Polyvinyl Alcohol Solution

[0187]

[0188]

[0189] Performance testing

[0190] Powder toughening materials were prepared according to the methods in Examples 1-5, and the volume average particle size of the powder toughening materials was statistically analyzed. The statistical results are recorded in Table 2.

[0191] Table 2. Statistical table of finished product particle size in Examples 1-5

[0192] Volume average particle size (Dv, μm) Example 1 52.24 Example 2 33.71 Example 3 19.93 Example 4 10.22 Example 5 24.79

[0193] The total amount of hydrophilic and lipophilic groups in a polyvinyl alcohol (PVA) solution has a certain influence on the particle size of the powder. Theoretically, the total amount of hydrophilic and lipophilic groups in the system can be adjusted by changing the mass or concentration of the PVA solution. However, since the volume of the reactor is fixed, this limits the amount of raw materials and the amount of PVA solution used. Furthermore, as the aqueous phase in the system, the ratio between the PVA solution and the oil phase (first solution) needs to be controlled within a certain range. Therefore, it is difficult to adjust the total amount of hydrophilic and lipophilic groups in the system by changing the mass of the PVA solution during production. Based on this, this application uses the mass concentration of the PVA solution as an indicator to control the total amount of hydrophilic and lipophilic groups in the system, which allows for a simpler adjustment of the particle size of the powder toughening material.

[0194] As shown in Table 2, the average volumetric particle size of the powder toughening material is affected by the mass concentration of the surfactant. When the amount of polyvinyl alcohol solution remains constant, the dispersion effect on macromolecules is limited due to the relatively small total amount of hydrophilic and lipophilic groups, resulting in greater macromolecular entanglement and thus a larger volumetric average particle size. When the mass concentration of the polyvinyl alcohol solution increases, the dispersion effect increases, the macromolecular entanglement is alleviated, and the corresponding volumetric average particle size decreases, showing a generally positive correlation with the mass concentration of the polyvinyl alcohol solution.

[0195] Furthermore, the mass concentration of the polyvinyl alcohol solution is the main factor affecting the particle size of the powder toughening material, while the stirring speed during the emulsification reaction can fine-tune the volume average particle size of the powder toughening material within a certain range. In summary, the method of this application can be used to directionally control the volume average particle size of the powder toughening material, and the adjustment method is simple and easy to implement.

[0196] It should be noted that, in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0197] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A method for directional control of the particle size of toughened powder materials for aerospace applications, used to prepare various toughened powder materials with different particle sizes, characterized in that... Includes the following steps: Different masses of polyvinyl alcohol, each corresponding to a different particle size of powder toughening material, were added to water, stirred and dissolved, and polyvinyl alcohol solutions of different mass concentrations were prepared. The thermoplastic plastic is added to an organic solvent and stirred until dissolved to obtain the first solution; Different mass concentrations of the polyvinyl alcohol solution were added to the first solution, and the mixture was stirred to dissolve, resulting in a second solution that corresponds to a variety of powder toughening materials with different particle sizes. After post-processing, each of the second solutions yields powder toughening materials with different particle sizes; When the mass concentration of the polyvinyl alcohol solution is 1-10 wt%, the volume average particle size of the obtained powder toughening material is 4-60 μm. The mass concentration of the polyvinyl alcohol solution is related to the volume average particle size of the powder toughening material. When preparing the second solution, the polyvinyl alcohol solution is added over a period of 35-45 minutes and the stirring speed is 200-300 rpm. The mass ratio of the thermoplastic to the polyvinyl alcohol solution is 1:8 to 1:9.5; The organic solvent is a single organic solvent or a complex organic solvent; The single organic solvent is N-methyl-2-pyrrolidone; The composite organic solvent is composed of 15-40 wt% methanol and 60-85 wt% chloroform; The thermoplastic content in the first solution is 5-15 wt%. The thermoplastic is either polyamide or polycarbonate.

2. The targeted control method according to claim 1, characterized in that, When the mass concentration of the polyvinyl alcohol solution is 2-4 wt%, the volume average particle size of the obtained powder toughening material is 30-55 μm. When the mass concentration of the polyvinyl alcohol solution is 4-5 wt%, the volume average particle size of the obtained powder toughening material is 15-30 μm. When the mass concentration of the polyvinyl alcohol solution is 5-8 wt%, the volume average particle size of the obtained powder toughening material is 7-15 μm.

3. The targeted control method according to claim 1, characterized in that, The mass ratio of the thermoplastic to the polyvinyl alcohol solution is 1:8 to 1:8.

5.

4. The targeted control method according to claim 1, characterized in that, When preparing the first solution, the dissolution temperature is 38-48℃, the stirring speed is 40-80rpm, and the dissolution time is 8-15h.

5. The targeted control method according to claim 4, characterized in that, When preparing the first solution, the dissolution temperature is 40-45℃, the stirring speed is 60-80rpm, and the dissolution time is 10-12h.

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