Sample preparation device and sample preparation method for testing interfacial shear strength of fiber and thermoplastic resin

Abstract

The invention relates to the technical field of mechanical property testing, and discloses a sample preparation device and a sample preparation method for testing interfacial shear strength of fiber and thermoplastic resin, the sample preparation device comprises a forming assembly, monofilament fiber connected to the forming assembly, and a monofilament fixing assembly for fixing the monofilament fiber, the forming assembly comprises a heating mechanism for accommodating and heating the thermoplastic resin and a forming mold communicated with the heating mechanism, and the monofilament fiber is fixed to penetrate through the forming mold to extend, so that thermoplastic resin micro-droplets can be formed on the monofilament fiber by the forming assembly. The thermoplastic resin to be detected is heated by utilizing the heating function of the heating mechanism, so that the thermoplastic resin can be in a molten state and drips and flows into the forming mold along the heating mechanism, manual sample preparation is not needed, the sample preparation accuracy is ensured, and the operation is convenient; meanwhile, the monofilament fibers fixedly penetrate through the forming mold, so that the thermoplastic resin in a molten state can be in contact with the monofilament fibers, and subsequent shear strength testing is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of mechanical property testing, and in particular to a sample preparation device and a sample preparation method for testing the shear strength of the interface between fiber and thermoplastic resin. Background Art

[0002] Fiber-reinforced thermoplastic resin composites have attracted more and more attention due to their high damage tolerance, recyclability, rapid and efficient molding, etc. However, compared with thermosetting resin composites, the interfacial compatibility between the reinforcement phase and the continuous phase of thermoplastic resin composites is more complex and requires a variety of characterization methods for analysis.

[0003] At present, the commonly used test of shear strength between fiber and resin is mostly tested by micro-debonding method. Compared with the macroscopic test method with insufficient accuracy, the microscopic test method can obtain the interfacial bonding strength of the material more directly and accurately. Among them, the micro-droplet debonding method is to form a small symmetrical resin droplet on the fiber monofilament, and then fix the resin droplet behind the card. The interfacial shear strength of the material is calculated by applying the magnitude of external force and the bonding length and using standardized consensus. However, this method is only applicable to thermosetting resins. For thermoplastic resins that are solid at room temperature and have a melting point generally greater than 100°C, this method does not have a heating and melting process. Even if an external oven is used, the accuracy of sample preparation cannot be guaranteed during the dripping process, resulting in large data dispersion.

[0004] Therefore, it is urgent to propose corresponding solutions to the problems of large manual errors and high data discreteness in the existing technology for micro-debonding test sample preparation of thermoplastic resins. Summary of the invention

[0005] The purpose of the present invention is to overcome the problems of large manual errors and high data dispersion in the prior art sample preparation for micro-debonding test of thermoplastic resins.

[0006] In order to achieve the above-mentioned objectives, the present invention provides, on one hand, a sample preparation device for testing the shear strength of the interface between fiber and thermoplastic resin, comprising a molding component, a monofilament fiber connected to the molding component, and a monofilament fixing component for fixing the monofilament fiber, wherein the molding component includes a heating mechanism for accommodating and heating the thermoplastic resin and a molding mold connected to the heating mechanism, and the monofilament fiber is fixed to extend through the molding mold so that thermoplastic resin droplets can be formed on the monofilament fiber by the molding component.

[0007] In some embodiments, a sealing plug is installed in the heating mechanism, and the sealing plug is connected to a hydraulic device to control the sealing plug to extrude the molten thermoplastic resin in the heating mechanism toward the molding die.

[0008] In some embodiments, a metal sheet is provided at the outlet end of the heating mechanism for controlling the on-off relationship between the heating mechanism and the forming die.

[0009] In some embodiments, the molding mold includes two semicircular molds spliced ​​to each other, and a through hole is opened at the center of the splicing surface of the semicircular mold along the extension direction of the monofilament fiber, and the diameter of the through hole is adapted to the diameter of the monofilament fiber.

[0010] In some embodiments, a clamp is provided on the outer side of the semicircular mold in the circumferential direction, and the clamp includes an upper clamp and a lower clamp that are arc-shaped and compatible with the forming mold. The upper clamp and the lower clamp are hinged at one end and connected by bolts at the other end.

[0011] In some embodiments, the monofilament fixing assembly includes a fixing plate connected to both ends of the monofilament fiber, and a support rod supported at the bottom of the fixing plate, the fixing plate includes a first fixing plate and a second fixing plate screwed to each other, and the monofilament fiber is connected to the connection between the first fixing plate and the second fixing plate by an adhesive.

[0012] The second aspect of the present invention provides a sample preparation method, comprising the following steps: S1, passing a monofilament fiber through a molding die for forming thermoplastic resin droplets, and fixing the two ends of the monofilament fiber by a monofilament fixing assembly; S2, cutting off the passage between the heating mechanism and the molding die, adding the thermoplastic resin to be tested into the heating mechanism, and heating the thermoplastic resin by the heating mechanism to melt the thermoplastic resin; S3, opening the passage between the heating mechanism and the molding die, allowing the molten thermoplastic resin to flow into the molding die, and after all the thermoplastic resin has flowed in, cutting off the passage between the heating mechanism and the molding die.

[0013] In some embodiments, the molding mold is formed by splicing two semicircles. In step S1, before the monofilament fiber passes through the molding mold, the inner surface of the molding mold is wiped with a soft cloth, and the molding mold is fastened with bolts; the two ends of the monofilament fiber are fixedly connected to the monofilament fixing assembly by an adhesive.

[0014] In some embodiments, in step S2, the passage between the heating mechanism and the forming die is cut off by inserting the metal sheet into the connection between the heating mechanism and the forming die.

[0015] In some embodiments, a sealing plug is installed in the heating mechanism, and the sealing plug is connected to a hydraulic device. In step S3, the hydraulic device is controlled to pressurize the sealing plug to squeeze the molten thermoplastic resin to flow smoothly into the molding die.

[0016] In the above technical scheme, the heating mechanism is connected to the molding die, and the heating function of the heating mechanism is used to heat the thermoplastic resin to be tested, so that it can be in a molten state and drip along the heating mechanism into the molding die to form thermoplastic resin droplets. There is no need for manual sample preparation, and the molten thermoplastic resin is heated to form droplets, which ensures the accuracy of sample preparation and convenient operation. At the same time, the monofilament fiber is fixed and passed through the molding die, so that the thermoplastic resin in a molten state can contact the monofilament fiber, which is convenient for subsequent shear strength testing. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of a sample preparation device disclosed in the present invention for testing the shear strength of the interface between fiber and thermoplastic resin.

[0018] Description of Reference Numerals

[0019] 1 Molding component 11 Heating mechanism

[0020] 12 Forming mold 13 Metal sheet

[0021] 14 Sealing plug 2 Monofilament fiber

[0022] 3 Monofilament fixing assembly 31 first fixing plate

[0023] 32 second fixing plate 33 support rod DETAILED DESCRIPTION

[0024] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the embodiments described herein are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0025] In the present invention, unless otherwise specified, the directions or positional relationships indicated by the directional words such as "up" and "down" are based on the directions or positional relationships shown in the drawings and are only for the convenience of describing the present design and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present design.

[0026] In the description of this design, it should be noted that, unless otherwise clearly specified and limited, the terms "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this design can be understood according to specific circumstances.

[0027] Furthermore, the terms "first", "second", "third", etc. are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] In order to overcome the problems of large manual errors and high data dispersion in the prior art sample preparation for micro-debonding test of thermoplastic resins.

[0029] like Figure 1 As shown, the present invention provides a sample preparation device for testing the shear strength of the interface between fiber and thermoplastic resin.

[0030] Embodiment 1

[0031] The sample preparation device for testing the shear strength of the interface between fiber and thermoplastic resin includes a molding component 1, a monofilament fiber 2 connected to the molding component 1, and a monofilament fixing component 3 for fixing the monofilament fiber 2, wherein the molding component 1 includes a heating mechanism 11 for accommodating and heating the thermoplastic resin and a molding die 12 connected to the heating mechanism 11, and the monofilament fiber 2 is fixed to extend through the molding die 12 so that thermoplastic resin droplets can be formed on the monofilament fiber 2 by the molding component 1.

[0032] Specifically, the heating mechanism 11 is connected to the molding die 12, and the heating function of the heating mechanism 11 is used to heat the thermoplastic resin to be tested, so that it can be in a molten state and drip along the heating mechanism 11 into the molding die 12 to form thermoplastic resin droplets. There is no need for manual sample preparation, and the molten thermoplastic resin is heated to form droplets, which ensures the accuracy of sample preparation and facilitates operation. At the same time, the monofilament fiber is fixed and passed through the molding die 12, so that the thermoplastic resin in a molten state can contact the monofilament fiber 2, which is convenient for subsequent shear strength testing.

[0033] Furthermore, the molding die 12 may also have a heating function to keep the molten thermoplastic resin flowing into the molding die 12 warm.

[0034] Embodiment 2

[0035] This embodiment includes all the contents of the first embodiment. And in this embodiment, refer to Figure 1As shown, a sealing plug 14 may be installed in the heating mechanism 11, and the sealing plug 14 is connected to a hydraulic device to control the sealing plug 14 to squeeze the molten thermoplastic resin in the heating mechanism 11 to flow toward the molding die 12. It is understandable that the thermoplastic resin can flow in a molten state after being heated by the heating mechanism 11, but bubbles may appear in the molten thermoplastic resin due to the different melting points and viscosities of the various components of the thermoplastic resin. Therefore, the sealing plug 14 may be pressurized by a hydraulic device to move the sealing plug 14 toward the molding die 12, thereby squeezing the molten thermoplastic resin that has reached the temperature in the heating mechanism 11 to flow toward the molding die 12, thereby avoiding bubbles between the molten thermoplastic resins.

[0036] Embodiment 3

[0037] This embodiment includes all the contents of the first embodiment. In this embodiment, a metal sheet 13 is provided at the outlet end of the heating mechanism 11 for controlling the on-off relationship between the heating mechanism 11 and the forming die 12. Figure 1 As shown, a metal sheet 13 can be inserted into the connection between the heating mechanism 11 and the forming mold 12 to cut off the passage between the heating mechanism 11 and the forming mold 12; in addition, the inserted metal sheet 13 can be pulled out to form a passage between the heating mechanism 11 and the forming mold 12, so that the molten thermoplastic resin in the heating mechanism 11 can flow into the forming mold 12. The metal sheet 13 can be controlled by a telescopic device, as long as it can be inserted or pulled out instantly to achieve the effect of controlling the connection and disconnection between the heating mechanism 11 and the forming mold 12.

[0038] Embodiment 4

[0039] This embodiment includes all the contents of the first embodiment. In this embodiment, the forming mold 12 includes two semicircular molds spliced ​​to each other, and a through hole is provided in the center of the splicing surface of the semicircular mold along the extension direction of the monofilament fiber 2, and the diameter of the through hole is adapted to the diameter of the monofilament fiber 2.

[0040] Specifically, the molding mold 12 can be formed by splicing two semicircular molds, and a through hole adapted to the diameter of the monofilament fiber 2 is formed at the splicing point of the two semicircular molds, so that the monofilament fiber 2 can extend through the through hole, thereby avoiding the formation of a gap between the monofilament fiber 2 and the molding mold 12, which causes inaccurate shear strength testing of the fiber and the thermoplastic resin.

[0041] Furthermore, a hoop is sleeved on the outer side of the semicircular mold along the circumferential direction, and the hoop includes an upper clamping plate and a lower clamping plate that are arc-shaped and matched with the forming mold 12, and one end of the upper clamping plate and the lower clamping plate are hinged, and the other end is connected by bolts. It can be understood that the outer surface of the forming mold 12 can be sleeved with a hoop along the circumferential direction, and the hoop can be composed of two arc-shaped clamping plates, one end of which is hinged to each other, and the other end is connected by bolts, so that it can clamp and fix the forming mold 12 to form a sealing structure, so as to prevent cracks from appearing between the forming mold 12 spliced ​​by two semicircular molds, resulting in leakage of molten thermoplastic resin.

[0042] Embodiment 5

[0043] This embodiment includes all the contents of the first embodiment. And in this embodiment, as Figure 1 As shown, the monofilament fixing assembly 3 includes a fixing plate connected to both ends of the monofilament fiber 2, and a support rod 33 supported at the bottom of the fixing plate. The fixing plate includes a first fixing plate 31 and a second fixing plate 32 screwed to each other, and the monofilament fiber 2 is connected to the connection between the first fixing plate 31 and the second fixing plate 32 by an adhesive.

[0044] Specifically, the connection between the first fixing plate 31 and the second fixing plate 32 and the two ends of the monofilament fiber 2 can be coated with adhesive, so that the two ends of the monofilament fiber 2 can be fixedly connected to the fixing plate, and the first fixing plate 31 and the second fixing plate 32 can be connected by bolts to further enhance the connection strength between the monofilament fiber 2 and the fixing plate, thereby avoiding the monofilament fiber 2 from falling off or shaking during the process of testing the shear strength between the fiber and the thermoplastic resin, thereby causing errors.

[0045] Embodiment 6

[0046] The second aspect of the present invention provides a sample preparation method, which includes the following steps: S1, passing a monofilament fiber 2 through a molding die 12 for forming thermoplastic resin droplets, and fixing both ends of the monofilament fiber 2 by a monofilament fixing assembly 3; S2, cutting off the passage between the heating mechanism 11 and the molding die 12, adding the thermoplastic resin to be tested into the heating mechanism 11, and heating the thermoplastic resin by the heating mechanism 11 to melt the thermoplastic resin; S3, opening the passage between the heating mechanism 11 and the molding die 12, allowing the molten thermoplastic resin to flow into the molding die 12, and after all the thermoplastic resin has flowed in, cutting off the passage between the heating mechanism 11 and the molding die 12.

[0047] Specifically, in step S1, the monofilament fiber 2 is extended through the molding die 12 so that the thermoplastic resin droplets formed in the molding die 12 can contact the monofilament fiber 2 to detect the shear strength between the fiber and the thermoplastic resin, and the two ends of the monofilament fiber 2 are fixed by the monofilament fixing component 3 to avoid the movement of the monofilament fiber 2 during the shear strength test, thereby causing errors. The appropriate monofilament fiber 2 can be selected under the illumination of an energy-saving lamp.

[0048] Specifically, in step S2, after the monofilament fiber 2 passes through the molding mold 12 and is fixed by the monofilament fixing assembly 3, the passage between the heating mechanism 11 and the molding mold 12 can be cut off first, and then the thermoplastic resin to be tested is added to the heating mechanism 11, and the heating function of the heating mechanism 11 is used to heat the thermoplastic resin.

[0049] Specifically, in step S3, after the thermoplastic resin in the heating mechanism 11 is heated to a suitable melting temperature, the passage between the heating mechanism 11 and the molding die 12 can be opened to allow the molten thermoplastic resin to flow into the molding die 12. After the molten thermoplastic resin has completely flowed into the molding die 12, the passage between the heating mechanism 11 and the molding die 12 is disconnected. The molding die 12 may also have a heating function, so that the molten thermoplastic resin flowing into the molding die 12 can be kept warm to form thermoplastic resin droplets.

[0050] Embodiment 7

[0051] This embodiment includes all the contents of the sixth embodiment. In this embodiment, the forming mold 12 is formed by splicing two semicircles. In step S1, before the monofilament fiber 2 passes through the forming mold 12, the inner surface of the forming mold 12 is wiped with a soft cloth, and the forming mold 12 is fastened with bolts; the two ends of the monofilament fiber 2 are fixedly connected to the monofilament fixing component 3 by an adhesive.

[0052] Specifically, the molding die 12 can be formed by splicing two semicircles. Before the monofilament fiber 2 passes through the molding die 12, the molding die 12 can be opened first, and the dust on the inner surface of the molding die 12 can be wiped off with a soft cloth to avoid errors. After the monofilament fiber 2 passes through the molding die 12, the molding die 12 formed by splicing two semicircles can be fastened and connected by a fastening device to form a sealing structure to prevent cracks from appearing between the molding dies 12, causing the molten thermoplastic resin to leak out. At the same time, the monofilament fixing component 3 can have two upper and lower fixing plates, and the fixing plates are used to clamp the monofilament fiber 2 to fix it. Among them, the monofilament fiber 2 can be bonded and fixed to the fixing plate by using an adhesive, and then the fixing plate is fastened by bolts to prevent the monofilament fiber 2 from falling off. Of course, in other embodiments, the monofilament fixing component 3 can also be in other forms, as long as the two ends of the monofilament fiber 2 can be fixed.

[0053] Embodiment 8

[0054] This embodiment includes all the contents of the sixth embodiment. In this embodiment, in step S2 , the passage between the heating mechanism 11 and the forming mold 12 is cut off by inserting a metal sheet 13 into the connection between the heating mechanism 11 and the forming mold 12 .

[0055] Specifically, a retractable metal sheet 13 can be installed at the connection between the heating mechanism 11 and the molding die 12. By controlling the expansion and contraction of the metal sheet 13, the metal sheet 13 can be inserted into the connection between the heating mechanism 11 and the molding die 12 to cut off the passage between the heating mechanism 11 and the molding die 12. The metal sheet 13 can also be pulled out to open the passage between the heating mechanism 11 and the molding die 12, so that the molten thermoplastic resin in the heating mechanism 11 can flow into the molding die 12.

[0056] Embodiment 9

[0057] This embodiment includes all the contents of the sixth embodiment. In this embodiment, a sealing plug 14 is installed in the heating mechanism 11 , and the sealing plug 14 is connected to a hydraulic device. In step S3 , the hydraulic device is controlled to pressurize the sealing plug 14 to squeeze the molten thermoplastic resin into the molding die 12 smoothly.

[0058] Specifically, a sealing plug 14 connected to an external hydraulic device can be installed in the heating mechanism 11, and the sealing plug 14 can be operated by the hydraulic device to squeeze the molten thermoplastic resin in the heating mechanism 11 so that it can all flow smoothly into the molding die 12. In addition, under the pressure of the sealing plug 14, bubbles can be avoided between the molten thermoplastic resins to cause errors.

[0059] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications. Including the combination of various specific technical features in any suitable manner. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations. However, these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A sample preparation device for testing the shear strength of the interface between fiber and thermoplastic resin, characterized in that: The invention comprises a molding component (1), a monofilament fiber (2) connected to the molding component (1), and a monofilament fixing component (3) for fixing the monofilament fiber (2), wherein the molding component (1) comprises a heating mechanism (11) for containing and heating a thermoplastic resin and a molding die (12) connected to the heating mechanism (11), and the monofilament fiber (2) is fixed to extend through the molding die (12) so that thermoplastic resin droplets can be formed on the monofilament fiber (2) by the molding component (1).

2. The sample preparation device for testing the shear strength of the interface between fiber and thermoplastic resin according to claim 1, characterized in that: A sealing plug (14) is installed in the heating mechanism (11), and the sealing plug (14) is connected to a hydraulic device to control the sealing plug (14) to squeeze the molten thermoplastic resin in the heating mechanism (11) toward the molding die (12).

3. The sample preparation device for testing the shear strength of the interface between fiber and thermoplastic resin according to claim 1, characterized in that: The outlet end of the heating mechanism (11) is provided with a metal sheet (13) for controlling the on-off relationship between the heating mechanism (11) and the forming die (12).

4. The sample preparation device for testing the shear strength of the interface between fiber and thermoplastic resin according to claim 1, characterized in that: The forming mold (12) comprises two semicircular molds spliced ​​to each other, and a through hole is provided at the center of the splicing surface of the semicircular mold along the extension direction of the monofilament fiber (2), and the diameter of the through hole is adapted to the diameter of the monofilament fiber (2).

5. The sample preparation device for testing the shear strength of the interface between fiber and thermoplastic resin according to claim 4, characterized in that: The outer side of the semicircular mold is sleeved with a hoop in the circumferential direction, and the hoop comprises an upper clamping plate and a lower clamping plate which are arc-shaped and matched with the forming mold (12), and one end of the upper clamping plate and the lower clamping plate are hinged and the other end is connected by bolts.

6. The sample preparation device for testing the shear strength of the interface between fiber and thermoplastic resin according to claim 1, characterized in that: The monofilament fixing assembly (3) comprises fixing plates connected to both ends of the monofilament fiber (2), and a support rod (33) supported at the bottom of the fixing plate, the fixing plate comprising a first fixing plate (31) and a second fixing plate (32) screwed to each other, and the monofilament fiber (2) is connected to the connection between the first fixing plate (31) and the second fixing plate (32) by an adhesive.

7. A sample preparation method, characterized in that: The steps include: S1, passing a monofilament fiber (2) through a molding die (12) for forming thermoplastic resin droplets, and fixing both ends of the monofilament fiber (2) by a monofilament fixing assembly (3); S2, cutting off the passage between the heating mechanism (11) and the molding die (12), adding the thermoplastic resin to be tested into the heating mechanism (11), and heating the thermoplastic resin by the heating mechanism (11) to melt the thermoplastic resin; S3, opening the passage between the heating mechanism (11) and the molding die (12) to allow the molten thermoplastic resin to flow into the molding die (12), and after all the molten thermoplastic resin has flowed into the molding die (12), disconnecting the passage between the heating mechanism (11) and the molding die (12).

8. The sample preparation method according to claim 7, characterized in that: The molding die (12) is formed by splicing two semicircles. In step S1, before the monofilament fiber (2) passes through the molding die (12), the inner surface of the molding die (12) is wiped with a soft cloth, and the molding die (12) is fastened with bolts; the two ends of the monofilament fiber (2) are fixedly connected to the monofilament fixing component (3) by an adhesive.

9. The sample preparation method according to claim 7, characterized in that: In step S2, the passage between the heating mechanism (11) and the forming die (12) is cut off by inserting the metal sheet (13) into the connection between the heating mechanism (11) and the forming die (12).

10. The sample preparation method according to claim 7, characterized in that: A sealing plug (14) is installed in the heating mechanism (11), and the sealing plug (14) is connected to a hydraulic device. In step S3, the hydraulic device is controlled to pressurize the sealing plug (14) to squeeze the molten thermoplastic resin into the molding die (12) smoothly.

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