A method for preparing a debonded test specimen of microbeads of a poorly soluble thermoplastic resin

Abstract

The application provides a microbead debonding sample preparation method of a poorly soluble thermoplastic resin, and relates to the technical field of composite materials.The application directly contacts a fiber monofilament with a poorly soluble thermoplastic resin melt after the fiber monofilament is straightened, so that the resin melt adheres to the fiber monofilament; the resin melt adhered to the fiber monofilament is spread, so that the resin wraps the monofilament, and the wrapped monofilament is cooled to obtain a fiber monofilament adhered with a thermoplastic resin; the fiber monofilament adhered with the thermoplastic resin is heated by a non-contact heating mode, so that the thermoplastic resin melts on the fiber monofilament and spontaneously shrinks into resin microbeads, and the microbeads are cooled to obtain a microbead debonding sample.The application can effectively control the size and position of the microbeads by the direct contact mode, and can also remelt and adjust the sample with poor sample preparation effect, so that the sample quality and success rate are improved; and the method has low operation difficulty and high preparation efficiency.

Description

Technical Field

[0001] This invention relates to the field of composite material technology, and in particular to a method for preparing microbead debonding samples of a poorly soluble thermoplastic resin. Background Technology

[0002] Thermoplastic composites, due to their high toughness, fatigue resistance, and reproducibility, can overcome the shortcomings of traditional thermosetting composites, such as insufficient toughness, easy delamination under low-speed impact, and low fatigue limit. Furthermore, combined with automated manufacturing technology, they can achieve low-cost and high-efficiency manufacturing, making them an important development direction in the field of composite materials. However, the lack of cross-linkable chemically active functional groups in the molecular structure of thermoplastic resins leads to weak bonding with reinforcing fibers. The interface, as a crucial component of composite materials, directly affects the transmission and distribution of stress within the material, as well as the initiation and propagation of cracks, thus significantly influencing the strength, toughness, heat resistance, and resistance to damp heat aging of composite materials. To evaluate the interfacial bonding strength of composite materials, various testing methods and techniques have been developed. Among them, the microbead debonding test, with its advantages of simple and direct principle, stress mode closely resembling the real environment, and simple sample preparation, has become one of the commonly used characterization testing methods for the interfacial properties of composite materials.

[0003] Microbead debonding tests require solidifying resin onto fiber monofilaments to form spherical resin microbeads. A test fixture is then used to peel the resin microbeads off the fiber monofilaments. By measuring the peel load, combined with the microbead size and fiber monofilament diameter, the interfacial debonding strength between the resin and fiber can be calculated, thus evaluating the interfacial properties of the composite material. Conventional thermosetting resins and a few soluble thermoplastic resins can be prepared into low-viscosity solutions. After impregnating the fiber monofilaments with the solution, the resin solution shrinks into small droplets on the fiber under surface tension. The solvent is then evaporated to obtain the debonded microbead sample. However, most high-temperature resistant thermoplastic resins (such as polyaryletherketones) cannot be prepared into solutions due to their chemical structure and poor crystallinity and solubility, making it impossible to prepare debonded microbead samples using solvent methods.

[0004] To address this problem, various methods for preparing microbead debonding samples of high-temperature resistant thermoplastic resins have been attempted, but the results have been unsatisfactory. For example, some researchers first drew thermoplastic resin into extremely fine resin filaments, then knotted the resin filaments onto fiber monofilaments, trimmed off excess resin filaments, and finally heated and melted the resin knots to obtain resin microbeads. However, this method requires extremely precise operation and is prone to breakage of the fiber monofilaments and resin filaments. Furthermore, the resin knots are structurally asymmetrical, resulting in microbeads that are often off-center and do not meet testing requirements. Additionally, this method can only prepare one microbead at a time, leading to low efficiency. Other researchers have sprinkled thermoplastic resin powder onto fiber monofilaments and then heated and melted the resin to prepare microbead debonding samples. However, the fiber monofilaments are extremely fine, even smaller than the average particle size of the ultrafine resin powder, making it extremely difficult to control the amount of resin on the sample. This results in microbeads that are too small, or even unable to form spherical microbeads.

[0005] In summary, existing methods for preparing microbead debonding samples of sparingly soluble thermoplastic resins are unsatisfactory in terms of operational difficulty, microbead quality, and sample preparation efficiency. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a method for preparing microbead debonding samples of sparingly soluble thermoplastic resins. The method for preparing microbead debonding samples provided by this invention is simple and can improve the quality controllability, success rate, and preparation efficiency of the microbead debonding samples.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing microbead debinding samples of a poorly soluble thermoplastic resin, comprising the following steps: (1) After straightening the fiber monofilament, it comes into direct contact with the melt of the sparingly soluble thermoplastic resin, so that the resin melt adheres to the fiber monofilament; The resin melt adhering to the fiber monofilament is spread out to coat the monofilament with resin, and then cooled to obtain fiber monofilaments with thermoplastic resin adhering to them. (2) The fiber monofilament with thermoplastic resin is heated by non-contact heating so that the thermoplastic resin melts on the fiber monofilament and spontaneously shrinks into resin microbeads. After cooling, the microbead debonding sample is obtained. The heating temperature is the melting point of the thermoplastic resin +50℃ to the melting point +105℃.

[0008] Preferably, the sparingly soluble thermoplastic resin melt is obtained by heating and melting a sparingly soluble thermoplastic resin, and the heating temperature for heating and melting is the melting point of the sparingly soluble thermoplastic resin +50℃ to the melting point +105℃.

[0009] Preferably, the insoluble thermoplastic resin includes polyetheretherketone, polyaryletherketone, polyimide, polyphenylene sulfide, derivatives of the above resins, or blends thereof; the viscosity of the melt of the insoluble thermoplastic resin is 0.1~1000 Pa·s.

[0010] Preferably, the fiber monofilament includes carbon fiber, glass fiber, quartz fiber, basalt fiber, ceramic fiber, organic fiber or metal fiber monofilament, and the diameter of the fiber monofilament is 5~20μm.

[0011] Preferably, the non-contact heating method is thermal radiation heating or hot air heating.

[0012] Preferably, the diameter of the resin microspheres is 30~100μm.

[0013] Preferably, when the diameter of the resin microspheres is greater than 100 μm, the process further includes remelting the resin in the debonded sample of the microspheres, removing part of the resin, cooling, and then repeating step (2).

[0014] Preferably, when the diameter of the resin microspheres is less than 30 μm, the process further includes dipping the microsphere debonded sample into the melt of a sparingly soluble thermoplastic resin, cooling it, and then repeating step (2).

[0015] Preferably, when the resin microspheres are eccentric, the process further includes heating and melting the resin in the microsphere debonding sample, re-spreading the resin to redistribute it on the fiber monofilament, cooling, and then repeating step (2).

[0016] This invention provides a method for preparing microbead debinding samples of sparingly soluble thermoplastic resin. Compared with the prior art, this invention has the following advantages: This invention involves straightening a monofilament fiber and then directly contacting it with a melt of a sparingly soluble thermoplastic resin. This allows the resin melt to adhere to the monofilament fiber. The resin melt is then spread out, encapsulating the monofilament, and cooled to obtain a monofilament fiber coated with thermoplastic resin. This invention uses a direct contact method, making the process of the monofilament fiber adsorbing the thermoplastic resin more controllable and effectively adjusting the amount and distribution of the thermoplastic resin adhering to the monofilament fiber. This invention heats the fiber monofilaments adhered with thermoplastic resin using a non-contact heating method. After the thermoplastic resin on the fiber monofilaments melts upon heating, due to the surface tension of the liquid, the molten resin tends to spontaneously and uniformly shrink, thereby forming regular spherical droplets on the fiber monofilaments. Furthermore, the non-contact heating method does not touch the fiber monofilaments or the thermoplastic resin adhering to them, thus avoiding changes in the amount and position of the thermoplastic resin adhering. Furthermore, when the preparation effect of the microbead debonding sample is not good (such as when the diameter of the resin microbeads is too large or too small or when there is eccentricity), the microbeads can be melted and adjusted to correct their size and position, and then remelted and shrunk to achieve the effect of remediation and repair, thereby improving sample quality and success rate.

[0017] The method for preparing microbead debonding samples provided by this invention is simple, easy to operate, and highly efficient. It can prepare several to dozens of microbead samples on a single fiber filament at one time, and can improve the quality controllability and success rate of microbead debonding samples. Attached Figure Description

[0018] Figure 1 This is a schematic diagram illustrating the preparation of the microbead debonding sample in the examples; Figure 2 This is a schematic diagram of the preparation of the microbead debonding sample using the wire drawing and knotting method in Comparative Example 1; Figure 3 The image shown is a photograph of the detached microbead sample from the example under an optical microscope. Figure 4 The image shown is a photograph of the final microbead debonding sample obtained in the example under an optical microscope. Detailed Implementation

[0019] This invention provides a method for preparing microbead debinding samples of a poorly soluble thermoplastic resin, comprising the following steps: (1) After straightening the fiber monofilament, it comes into direct contact with the melt of the sparingly soluble thermoplastic resin, so that the resin melt adheres to the fiber monofilament; The resin melt adhering to the fiber monofilament is spread out to coat the monofilament with resin, and then cooled to obtain fiber monofilaments with thermoplastic resin adhering to them. (2) The fiber monofilament with thermoplastic resin is heated by non-contact heating so that the thermoplastic resin melts on the fiber monofilament and spontaneously shrinks into resin microbeads. After cooling, the microbead debonding sample is obtained. The heating temperature is the melting point of the thermoplastic resin +50℃ to the melting point +105℃.

[0020] Unless otherwise specified, all raw materials or equipment involved in this invention are commercially available products in the field.

[0021] This invention involves straightening a fiber monofilament and then bringing it into direct contact with a sparingly soluble thermoplastic resin melt, causing the resin melt to adhere to the fiber monofilament.

[0022] In this invention, the sparingly soluble thermoplastic resin melt is preferably obtained by heating and melting a sparingly soluble thermoplastic resin. In this invention, the sparingly soluble thermoplastic resin is a thermoplastic resin that is difficult to dissolve in solvents and difficult to prepare solutions from. In this invention, the sparingly soluble thermoplastic resin preferably includes polyetheretherketone, polyaryletherketone, polyimide, polyphenylene sulfide, derivatives of the above resins, or blends thereof, wherein the above thermoplastic resin is a high-temperature resistant thermoplastic resin; the viscosity of the melt after melting the sparingly soluble thermoplastic resin is preferably 0.1~1000 Pa·s (the viscosity is the apparent viscosity measured using a rotational rheometer, ASTM D4440). In this invention, the heating temperature for heating and melting is preferably the melting point of the sparingly soluble thermoplastic resin +50℃ to the melting point +105℃; the heating temperature is set to a temperature higher than the melting point of the thermoplastic resin to ensure that the thermoplastic resin is completely melted and possesses good fluidity, adhesion, and lubricity, laying the foundation for subsequent steps.

[0023] In this embodiment of the invention, the heating and melting involves placing the sparingly soluble thermoplastic resin on the surface of a heater or worktable preheated to the heating temperature for melting. In this invention, the heater is a device with a heated surface or worktable, capable of heating through direct heat conduction from the surface; preferably, the heater has an open heating structure, facilitating direct absorption of the molten thermoplastic resin from the heater surface by the fiber filaments; specifically, the heater can be a heating table, soldering iron, heating rod, or electric hot knife. In this invention, the placement method can be to sprinkle the sparingly soluble thermoplastic resin in powder form onto the surface of the heater or worktable preheated to the heating temperature.

[0024] In this invention, the fiber monofilament preferably includes carbon fiber, glass fiber, quartz fiber, basalt fiber, ceramic fiber, organic fiber, or metal fiber monofilament, and the diameter of the fiber monofilament is preferably 5~20μm. This invention preferably straightens and fixes the fiber monofilament to facilitate subsequent movement of the fiber monofilament and the operation of using the fiber monofilament to dip into and wipe away the thermoplastic resin melt.

[0025] In this embodiment of the invention, the preferred method of direct contact with the molten, insoluble thermoplastic resin is to directly contact the fiber monofilament with the molten, insoluble thermoplastic resin on the surface of the heater or the table, so that the fiber monofilament is dipped in the thermoplastic resin and the resin melt adheres to the fiber monofilament.

[0026] After the resin melt is adhered to the fiber monofilament, the present invention spreads the resin melt adhered to the fiber monofilament, so that the resin coats the monofilament, and cools it to obtain a fiber monofilament with thermoplastic resin.

[0027] In an embodiment of the present invention, the preferred method for spreading the resin melt adhering to the fiber monofilament is to bring the heater into contact with the resin melt adhering to the fiber monofilament, and then move the heater (with the fiber monofilament fixed) to spread the resin melt adhering to the fiber monofilament, thereby forming a uniform and continuous resin coating layer.

[0028] In this invention, the cooling is preferably performed by natural cooling to room temperature. After cooling, the thermoplastic resin is solidified on the fiber monofilament, resulting in a fiber monofilament coated with thermoplastic resin.

[0029] This invention employs a method of directly contacting the monofilament fiber with a sparingly soluble thermoplastic resin melt. This allows for convenient adjustment of the amount of thermoplastic resin adhering to the monofilament fiber, thereby controlling the size of the microspheres in the final microsphere debonding sample. Subsequent application of the resin melt adhering to the monofilament fiber facilitates adjustment of the resin distribution, ensuring uniform resin distribution and reducing eccentricity. When the amount of thermoplastic resin adhering to the monofilament fiber is excessive, the prepared resin microspheres (or resin microspheres) have a larger diameter, potentially causing the debonding force to exceed the fiber's breaking limit. Simultaneously, a large amount of thermoplastic resin reduces the surface tension of the resin melt, exacerbating the gravitational influence on the resin droplets and leading to uneven resin distribution around the monofilament fiber. This can cause the prepared microspheres to deviate from the fiber axis, failing to meet the requirements for a microsphere debonding sample. Conversely, when the amount of thermoplastic resin adhering to the monofilament fiber is too small, the prepared microspheres have a smaller diameter, potentially smaller than the blade clamping limit of the microsphere debonding test equipment, making testing impossible.

[0030] After obtaining the fiber monofilaments adhered to thermoplastic resin, the present invention heats the fiber monofilaments adhered to thermoplastic resin by a non-contact heating method, so that the thermoplastic resin melts on the fiber monofilaments and spontaneously shrinks into resin microbeads. After cooling, a microbead debonding sample is obtained.

[0031] In this invention, the non-contact heating method is preferably thermal radiation heating or hot air heating. Thermal radiation heating can utilize the thermal radiation effect of heaters such as heating tables, soldering irons, heating rods, or electric hot knives described in the above technical solutions. The distance between the heater and the fiber monofilaments adhered to the thermoplastic resin is preferably 5-10 mm. Hot air heating involves placing the fiber monofilaments adhered to the thermoplastic resin in an oven for heating. When using a non-contact heating method, the heater will not touch the fiber monofilaments or the thermoplastic resin adhering to them, thus avoiding changes in the amount and position of the thermoplastic resin adhering.

[0032] In this invention, the heating temperature for heating the fiber monofilaments bonded with thermoplastic resin is the melting point of the thermoplastic resin +50°C to +105°C. This heating temperature is set higher than the melting point of the thermoplastic resin to ensure complete melting and good fluidity, allowing surface tension to drive the resin to shrink into microdroplets (in this invention, the sparingly soluble thermoplastic resin has a high molecular weight, strong cohesion, and high viscosity, and will spontaneously agglomerate into spherical melts upon heating). In this invention, after the thermoplastic resin melts, it is preferably held for 30 seconds to 5 minutes.

[0033] In this invention, the diameter of the resin microspheres is preferably 30~100μm (the resin mass corresponding to a single resin microsphere is 1~3mg).

[0034] Figure 1 This is a schematic diagram illustrating the preparation of a microbead debonding sample according to an embodiment of the present invention. A single fiber filament is straightened and fixed to a "U"-shaped cardboard using adhesive. The single fiber filament fixed to the cardboard is then brought into direct contact with molten thermoplastic resin, causing the resin melt to adhere to the fiber filament. The resin melt adhering to the fiber filament is spread out, allowing the molten thermoplastic resin to encapsulate the fiber filament. After cooling, a resin layer is formed, resulting in a single fiber filament coated with thermoplastic resin. The single fiber filament coated with thermoplastic resin is then heated using a non-contact heating method, causing the thermoplastic resin to melt on the single fiber filament and spontaneously shrink into multiple resin microbeads. After cooling, a microbead debonding sample is obtained.

[0035] In this invention, when the diameter of the resin microspheres is too large (greater than 100 μm), it is preferable to further include remelting the resin in the debonded sample of the microspheres, removing a portion of the resin, cooling, and then repeating step (2). The remelting, removal, cooling, and repetition of step (2) can be performed multiple times until the diameter of the resin microspheres meets the requirements (the size of the microspheres can be observed under a microscope). In an embodiment of this invention, the preferred specific operation of remelting the resin in the debonded sample of the microspheres and removing a portion of the resin is as follows: preheating the heater (temperature to the melting point of the thermoplastic resin +50°C to melting point +105°C), carefully touching and rubbing the fiber monofilaments in the debonded sample of the microspheres with the hot surface or platform of the heater, so as to adhere a portion of the resin from the fiber monofilaments to the hot surface or platform of the heater, thereby reducing the size of the microspheres.

[0036] In this invention, when the diameter of the resin microspheres is too small (less than 30 μm), it is preferable to further include dipping the microsphere debonding sample into the melt of insoluble thermoplastic resin, cooling it, and then repeating step (2). The dipping into the melt of insoluble thermoplastic resin, cooling it, and repeating step (2) can be performed multiple times until the diameter of the resin microspheres meets the requirements. In an embodiment of this invention, the specific operation of dipping the microsphere debonding sample into the melt of insoluble thermoplastic resin is preferably: the fiber monofilament in the microsphere debonding sample comes into contact with the molten thermoplastic resin placed on the hot surface or platform of the heater, so as to adhere more resin from the hot surface or platform of the heater to the surface of the fiber monofilament, thereby increasing the size of the microspheres.

[0037] In this invention, when the resin microspheres become eccentric, it is preferable to further include heating and melting the resin in the microsphere debonding sample, redistributing the resin on the fiber monofilaments, cooling, and then repeating step (2); the above operation can be performed multiple times until the resin microspheres are no longer eccentric. The microsphere debonding sample is rotated while the resin microspheres are heated, so that the resin is redistributed on the fiber monofilaments. In the embodiments of this invention, the specific operation of redistributing the resin is preferably as follows: the hot surface or platform of the heater (temperature to the melting point of the thermoplastic resin +50°C to the melting point +105°C) is carefully touched to the fiber monofilaments in the microsphere debonding sample, and then the hot surface or platform of the heater is rotated to evenly coat and wrap the resin on the surface of the fiber monofilaments.

[0038] In this invention, when the preparation effect of the microbead debonding sample is not good, the microbeads can be remelted and adjusted to avoid the microbeads being too large or too small, reduce the generation of eccentric microbeads, and significantly improve the sample preparation effectiveness.

[0039] Most high-temperature resistant thermoplastic resin systems have poor solubility, resulting in limited and complex methods for preparing microbead debonding samples. Furthermore, existing methods are inefficient, typically producing only one microbead sample per fiber filament at a time. In addition, the microbeads prepared by existing methods are generally large and randomly sized, making effective control impossible. Moreover, the microbeads often deviate from the fiber filament axis, exhibiting an eccentric state that does not meet sample requirements, leading to a very high failure rate. This invention provides a method for preparing microbead debonding samples of sparingly soluble thermoplastic resins, simplifying the process, reducing operational difficulty, and effectively improving sample controllability, success rate (increasing yield), and preparation efficiency (preparing several to dozens of microbead samples per fiber filament at a time). This invention provides a simple, convenient, stable, controllable, rapid, and efficient new method for preparing microbead debonding samples of sparingly soluble thermoplastic resins.

[0040] To further illustrate the present invention, the method for preparing microbead debonding samples of sparingly soluble thermoplastic resin provided by the present invention is described in detail below with reference to examples, but these should not be construed as limiting the scope of protection of the present invention.

[0041] Example 1 A method for preparing microbead debonding samples of a poorly soluble, high-temperature resistant thermoplastic resin, comprising the following steps: (1) such as Figure 1 As shown, carbon fiber monofilaments (5~8μm in diameter) are separated from the fiber bundle with tweezers and straightened, and then fixed to a "U"-shaped cardboard with glue.

[0042] (2) Preheat the soldering iron to 400°C, then sprinkle polyaryletherketone (PAEK) resin (melting point 345°C, melt index 70g / 10min (380°C, 5kg)) powder onto it, so that the resin melts into droplets.

[0043] (3) Slowly bring the carbon fiber monofilament fixed to the cardboard close to the resin droplet on the soldering iron. Through mutual contact, the resin droplet on the soldering iron adheres to the carbon fiber monofilament.

[0044] (4) Move the soldering iron to make it contact the resin melt on the carbon fiber monofilament, and then spread the resin droplets adhering to the carbon fiber monofilament by moving the soldering iron (fixing the carbon fiber monofilament), so that the molten thermoplastic resin wraps the carbon fiber monofilament. Remove the soldering iron, and the resin cools down to form a resin layer that wraps the carbon fiber monofilament.

[0045] (5) Increase the temperature of the soldering iron to 450°C.

[0046] (6) Bring the soldering iron close to the thermoplastic resin adhering to the carbon fiber monofilament (5 mm apart) and heat it to melt the thermoplastic resin on the carbon fiber monofilament. Hold for 30 seconds to allow the resin to melt fully and spontaneously shrink into multiple microbeads. Then remove the soldering iron to allow the sample to cool.

[0047] (7) Observe the morphology of microbeads on carbon fiber monofilaments using an optical microscope. If the microbeads meet the requirements, the microbead debonding sample preparation is completed. If there are microbeads that are too large, too small, or eccentric, adjust them according to the subsequent steps (8) to (9).

[0048] (8) Preheat the soldering iron to 400°C. For microbeads that are too large, carefully touch and rub them with the part of the soldering iron that is not covered with thermoplastic resin to transfer some resin from the carbon fiber monofilament to the surface of the soldering iron, thereby reducing the size of the microbeads. For microbeads that are too small, carefully touch them with the part of the soldering iron (400°C) that is covered with thermoplastic resin to transfer more resin from the soldering iron to the surface of the carbon fiber monofilament, thereby increasing the size of the microbeads. For eccentric microbeads (such as...) Figure 3 Carefully touch the surface with a soldering iron (400℃), then rotate the soldering iron (to fix the carbon fiber monofilament) to evenly coat and wrap the resin on the surface of the carbon fiber monofilament, so as to promote the uniform shrinkage of the resin droplets and thus alleviate and avoid eccentricity.

[0049] (9) Repeat steps (5) to (7) until a microbead debonding sample that meets the requirements is obtained.

[0050] Figure 4 The image shows the final debonded microsphere sample under an optical microscope. The microspheres on the carbon fiber monofilaments are relatively regular in shape and not eccentric (the diameters of the resin microspheres are 45.29 μm, 34.25 μm, and 42.98 μm).

[0051] Example 2 A method for preparing microbead debonding samples of a poorly soluble, high-temperature resistant thermoplastic resin, comprising the following steps: (1) such as Figure 1 As shown, glass fiber monofilaments (10~20μm in diameter) are separated from the fiber bundle with tweezers and straightened, and then fixed to a "U"-shaped cardboard with glue.

[0052] (2) Preheat the hot table to 330°C, then sprinkle polyphenylene sulfide (PPS) resin powder (melting point 280°C, melt index 80g / 10min (320°C, 5kg)) onto it to melt the resin into droplets.

[0053] (3) Slowly bring the glass fiber monofilament fixed to the cardboard close to the resin droplet on the hot table. Through mutual contact, the resin droplet on the hot table adheres to the glass fiber monofilament.

[0054] (4) Move the hot table surface to contact the resin melt on the glass fiber monofilament, and then spread the resin droplets adhering to the glass fiber monofilament by moving the hot table surface, so that the molten thermoplastic resin can wrap the glass fiber monofilament, cool, and form a resin layer.

[0055] (5) Remove the glass fiber monofilament.

[0056] (6) Place the glass fiber monofilament into an oven preheated to 330°C, so that the thermoplastic resin melts on the glass fiber monofilament. Keep it for 5 minutes to allow the resin to melt fully and spontaneously shrink into multiple microbeads. Then remove the glass fiber monofilament and allow the sample to cool.

[0057] (7) Observe the morphology of microbeads on glass fiber monofilaments using an optical microscope. If the microbeads meet the requirements, the microbead debonding sample preparation is completed. If there are microbeads that are too large, too small, or eccentric, adjust them according to the subsequent steps (8) to (9).

[0058] (8) Preheat the hot stage to 330°C. For microbeads that are too large, carefully touch and rub the glass fiber monofilament with the part of the hot stage that is not covered with thermoplastic resin to transfer some of the resin from the glass fiber monofilament to the surface of the hot stage to reduce the size of the microbeads. For microbeads that are too small, carefully touch the glass fiber monofilament with the part of the hot stage (330°C) covered with thermoplastic resin to transfer more resin from the hot stage to the surface of the glass fiber monofilament to increase the size of the microbeads. For eccentric microbeads, carefully touch the glass fiber monofilament with the hot stage (330°C), and then rotate the hot stage (with the glass fiber monofilament fixed) to evenly coat and wrap the resin on the surface of the glass fiber monofilament to promote the uniform shrinkage of the resin droplets, thereby alleviating and avoiding eccentricity.

[0059] (9) Repeat steps (5) to (7) until a microbead debonding sample that meets the requirements is obtained.

[0060] Comparative Example 1 Using Example 1 as the control group, Comparative Example 1 prepared microbead debonding samples using the traditional wire drawing and knotting method, with the same material type, as follows: (1) such as Figure 2 As shown, the carbon fiber monofilaments are separated from the bundle with tweezers and straightened, and then fixed to a "U"-shaped cardboard with glue.

[0061] (2) Preheat the soldering iron to 400°C, then sprinkle polyaryletherketone (PAEK) resin powder onto it to melt the resin into droplets.

[0062] (3) Use tweezers to pick up the resin droplets and quickly pull them away to draw the resin into a thin filament with a diameter of 5~10μm.

[0063] (4) such as Figure 2 As shown, the resin filaments are carefully manipulated with tweezers to tie and tighten them onto the carbon fiber monofilaments.

[0064] (5) Trim off the excess filaments at both ends of the resin knot.

[0065] (6) Place the carbon fiber monofilament with the resin knot in a high-temperature vacuum oven, heat it to 400℃ and keep it for 5 minutes to allow the resin knot to melt fully and spontaneously shrink into a microbead. Then take out the sample and cool it.

[0066] (7) Observe the morphology of microbeads on carbon fiber monofilaments using an optical microscope. If the microbeads meet the requirements, the microbead debonding sample preparation is completed. If there are microbeads that are too large, too small, or eccentric, steps (1) to (6) need to be repeated to prepare the sample again.

[0067] Comparing Comparative Example 1 and Example 1, it can be seen that: Comparative Example 1 involved a complex and difficult process in preparing the microbead debonding sample. Steps such as drawing, winding, threading, knotting, tightening, and cutting all required handling micron-sized filaments. This not only involved complex movements but also required applying sufficient force, making it highly susceptible to breakage of the resin filaments or individual fiber filaments, leading to sample preparation failure. In contrast, Example 1 only required the individual fiber filaments to come into contact with the molten resin and rub gently. This process was highly operable, had a high tolerance for error, and was much simpler.

[0068] Furthermore, the size of the microbeads prepared in Comparative Example 1 is determined by the thickness of the resin filaments and the amount of resin remaining after knotting and cutting. These steps require extremely high precision and are difficult to control accurately. Simultaneously, the knotted structure inevitably results in a non-uniform and asymmetrical distribution of resin around the fiber monofilaments, making it easy to obtain eccentric microbead samples. If the sample preparation is unsatisfactory, it must be repeated. In contrast, Example 1 allows for repeated fine-tuning, effectively controlling the amount and distribution of resin on the fiber monofilaments, thereby significantly improving sample quality.

[0069] Furthermore, Comparative Example 1 could only prepare one microbead sample at a time, resulting in extremely low sample preparation efficiency. In contrast, Example 1 could prepare multiple samples at a time, significantly improving sample preparation efficiency.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing microbead debinding samples of a sparingly soluble thermoplastic resin, characterized in that, Includes the following steps: (1) After straightening the fiber monofilament, it comes into direct contact with the melt of the sparingly soluble thermoplastic resin, so that the resin melt adheres to the fiber monofilament; The resin melt adhering to the fiber monofilament is spread out to coat the monofilament with resin, and then cooled to obtain fiber monofilaments with thermoplastic resin adhering to them. (2) The fiber monofilament with thermoplastic resin is heated by non-contact heating so that the thermoplastic resin melts on the fiber monofilament and spontaneously shrinks into resin microbeads. After cooling, the microbead debonding sample is obtained. The heating temperature is the melting point of the thermoplastic resin +50℃ to the melting point +105℃.

2. The method for preparing microbead debonding samples of sparingly soluble thermoplastic resin according to claim 1, characterized in that, The sparingly soluble thermoplastic resin melt is obtained by heating and melting the sparingly soluble thermoplastic resin, and the heating temperature for heating and melting is the melting point of the sparingly soluble thermoplastic resin +50℃ to the melting point +105℃.

3. The method for preparing microbead debonding samples of sparingly soluble thermoplastic resin according to claim 2, characterized in that, The sparingly soluble thermoplastic resin includes polyetheretherketone, polyaryletherketone, polyimide, polyphenylene sulfide, derivatives of the above resins, or blends thereof; the viscosity of the sparingly soluble thermoplastic resin melt is 0.1~1000 Pa·s.

4. The method for preparing microbead debonding samples of sparingly soluble thermoplastic resin according to claim 1, characterized in that, The fiber monofilaments include carbon fiber, glass fiber, quartz fiber, basalt fiber, ceramic fiber, organic fiber or metal fiber monofilaments, and the diameter of the fiber monofilaments is 5~20μm.

5. The method for preparing microbead debonding samples of sparingly soluble thermoplastic resin according to claim 1, characterized in that, The non-contact heating method is thermal radiation heating or hot air heating.

6. The method for preparing microbead debonding samples of sparingly soluble thermoplastic resin according to any one of claims 1 to 5, characterized in that, The diameter of the resin microspheres is 30~100μm.

7. The method for preparing microbead debonding samples of sparingly soluble thermoplastic resin according to claim 1, characterized in that, When the diameter of the resin microspheres is greater than 100 μm, the process further includes remelting the resin in the debonded sample of the microspheres, removing part of the resin, cooling, and then repeating step (2).

8. The method for preparing microbead debonding samples of sparingly soluble thermoplastic resin according to claim 1, characterized in that, When the diameter of the resin microspheres is less than 30 μm, the process also includes dipping the microsphere debonded sample into the melt of a sparingly soluble thermoplastic resin, cooling it, and then repeating step (2).

9. The method for preparing microbead debonding samples of sparingly soluble thermoplastic resin according to claim 1, characterized in that, When the resin microspheres become eccentric, the process also includes heating and melting the resin in the microsphere debonding sample, spreading the resin back onto the fiber monofilament, cooling, and then repeating step (2).

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