A method for testing the adhesive strength of liquid silicone rubber

Abstract

The application belongs to the technical field of material strength test, and particularly relates to a liquid silicone rubber adhesive strength test method. The method comprises the following steps: S1, uniformly mixing components of liquid silicone rubber according to a set proportion; S2, placing the liquid silicone rubber in a vacuum device and vacuumizing under a set pressure; S3, smearing liquid silicone rubber glue on adhesive surfaces of two metal cylindrical clamps; S4, abutting the adhesive surfaces of the two metal cylindrical clamps to form a sample assembly; S5, placing the sample assembly on a gravity loading clamp; S6, placing the gravity loading clamp with the sample assembly in a vulcanization environment for vulcanization treatment under a set temperature; and S7, connecting the metal cylindrical clamps of the sample assembly to a tension load loading device respectively to apply tension and test the adhesive strength of the liquid silicone rubber. The application simplifies a sample preparation method, reduces a connecting structure of a sample clamp, and improves the preparation and assembly efficiency of the whole sample.

Description

Technical Field

[0001] This application belongs to the field of material strength testing technology, specifically relating to a method for testing the adhesive strength of liquid silicone rubber. Background Technology

[0002] To avoid the influence of shearing, bending, or other forces, testing the adhesive strength of liquid silicone rubber alone requires determining its pure adhesive strength. The adhesive strength of rubber reflects the force required for the separation of the adhesive interface and is the most commonly used method for evaluating adhesive quality; it is a crucial technical indicator in bonding. Adhesive strength refers to the stress required to cause failure of the interface system between the adhesive and the bonded material under external force. The magnitude of adhesive strength depends not only on the adhesive force of the adhesive, the mechanical properties of the adhesive, and the properties of the bonded material, but also on the bonding process, the surface treatment of the bonded material, the joint type, the stress conditions (type, magnitude, direction, frequency), environmental factors (temperature, humidity, pressure, medium), testing conditions, and experimental techniques. Because actual adhesive strength is affected by various factors, there is a significant difference between the adhesive force (the theoretical value calculated based on intermolecular forces) and the actually measured adhesive strength.

[0003] To fully demonstrate the properties of the rubber bond itself, a butt joint method is generally used, where two bonded materials are joined together after applying adhesive to their ends. Due to the small bonding area and lower load capacity, this method better reflects the inherent properties of the rubber bond. The current national standard is GB / T 11211-2009, "Determination of Bond Strength between Vulcanized Rubber or Thermoplastic Rubber and Metal - Two-Plate Method". However, the butt joint described in the standard is prone to force direction shift under load, leading to bending forces and stress concentration. Under such forces, the rubber is susceptible to splitting stress. This method is primarily for determining the bond strength between solid rubber materials requiring mold forming and heated vulcanization at specific temperatures and pressures and metals; its applicability to liquid silicone rubber is poor. Furthermore, the test fixtures for fixing the rubber and metal bonded samples are placed vertically, such as... Figure 1As shown, during the preparation of the standard specimen, the upper circular metal plate 1, rubber specimen 2, and lower circular metal plate 3 are prone to misalignment. The overall thickness of the standard specimen does not exceed 3 cm. Due to this thinness, it is difficult to ensure the coaxiality of the three components, leading to insufficient contact area to meet the test size requirements. Furthermore, when fixing the rubber and metal bonded specimens in the test fixture assembly, misalignment issues arise with the tail bolt 4 connecting to the testing machine, the connecting piece 5 assembling the specimen, and the limiting block 6. This results in the test direction and the specimen's gravity direction not being on the same axis, creating component forces and ultimately leading to inaccurate test results. Additionally, the upper and lower circular metal plates, the tail bolt connecting to the testing machine, the connecting piece assembling the specimen, and the limiting block used in the test fixture are structurally complex and require high precision, making them difficult to manufacture. Summary of the Invention

[0004] To address the aforementioned problems, this application provides a method for testing the adhesive strength of liquid silicone rubber, mainly comprising:

[0005] Step S1: Mix the components of the liquid silicone rubber evenly according to the set ratio;

[0006] Step S2: Place the mixed liquid silicone rubber solution in a vacuum device and evacuate it under a set pressure;

[0007] Step S3: Apply the vacuum-sealed liquid silicone rubber adhesive to the bonding surfaces of the two metal cylindrical clamps. One end of each metal cylindrical clamp has a bonding surface, and the other end is provided with an external thread that can be adapted to connect a tensile load loading device.

[0008] Step S4: Join the adhesive surfaces of the two metal cylindrical clamps together to form a sample assembly;

[0009] Step S5: Place multiple sample assemblies on a gravity loading fixture, which has multiple inclined slots, each slot being adapted to accommodate one sample assembly.

[0010] Step S6: Place the gravity loading fixture containing the sample assembly into the vulcanization environment for vulcanization treatment at the set temperature.

[0011] Step S7: Connect each metal cylindrical clamp of the sample assembly to a tensile load loading device, apply tensile force to the mutually bonded metal cylindrical clamps based on the tensile load loading device, and test the bonding strength of the liquid silicone rubber.

[0012] Preferably, the metal cylindrical clamp is made of stainless steel.

[0013] Preferably, the metal cylindrical clamp is made of titanium alloy.

[0014] Preferably, the dimensions of the metal cylindrical clamp are set such that the ratio of its length to its diameter is between 1 and 2, and the length of the external thread is not less than 20 mm.

[0015] Preferably, the gravity loading fixture is configured such that when the gravity loading fixture is stably installed on the test bench plane, the extension direction of the strip groove makes an angle of 59 to 61° with the horizontal plane.

[0016] Preferably, after step S6, the process further includes cleaning away any residual silicone rubber around the adhesive surface of the metal cylindrical clamp.

[0017] This application simplifies the sample preparation method, reduces the connection structure of the sample fixture, reduces the number of parts, simplifies the preparation process, improves the overall preparation and assembly efficiency of the sample, reduces manufacturing and measurement errors, and fully leverages the weight reduction advantages of composite materials. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of an existing test fixture for fixing rubber and metal bonded specimens.

[0019] Figure 2 This is a schematic diagram of the sample assembly structure of a preferred embodiment of the liquid silicone rubber adhesive strength test method of this application.

[0020] Figure 3 This is a schematic diagram of a gravity loading fixture structure of a preferred embodiment of the liquid silicone rubber adhesive strength test method of this application.

[0021] Among them, 1-upper circular metal plate, 2-rubber sample, 3-lower circular metal plate, 4-tail bolt, 5-connector, 6-limiting block, 7-first metal cylindrical clamp, 8-second metal cylindrical clamp, 9-gravity loading clamp, 10-strip groove. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are only some, not all, of the embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0023] This application provides a method for testing the adhesive strength of liquid silicone rubber, mainly including:

[0024] Step S1: Mix the components of the liquid silicone rubber evenly according to the set ratio;

[0025] Step S2: Place the mixed liquid silicone rubber solution in a vacuum device and evacuate it under a set pressure;

[0026] Step S3: Apply the vacuum-sealed liquid silicone rubber adhesive to the bonding surfaces of the two metal cylindrical clamps. One end of each metal cylindrical clamp has a bonding surface, and the other end is provided with an external thread that can be adapted to connect a tensile load loading device.

[0027] Step S4: Join the adhesive surfaces of the two metal cylindrical clamps together to form a sample assembly;

[0028] Step S5: Place multiple sample assemblies on a gravity loading fixture, which has multiple inclined slots, each slot being adapted to accommodate one sample assembly.

[0029] Step S6: Place the gravity loading fixture containing the sample assembly into the vulcanization environment for vulcanization treatment at the set temperature.

[0030] Step S7: Connect each metal cylindrical clamp of the sample assembly to a tensile load loading device, apply tensile force to the mutually bonded metal cylindrical clamps based on the tensile load loading device, and test the bonding strength of the liquid silicone rubber.

[0031] This application employs two metal cylindrical clamps, such as Figure 2 As shown, the bonding surfaces of the first metal cylindrical clamp 7 and the second metal cylindrical clamp 8 are connected to each other, and the liquid silicone rubber in the middle forms a rubber cylindrical sheet. The clamp is made of stainless steel or titanium alloy. One end of the clamp is the bonding surface, and the other end has threads. Liquid silicone rubber is applied to the bonding surface of each clamp to form a coating. The length-to-diameter ratio of the clamp is 2:1 to 1:1, and the thread length is at least 20mm.

[0032] The sample preparation process of this application involves first mixing the components of the liquid silicone rubber evenly according to the proportions required by the material specifications, and then evacuating the sample in a vacuum device under a certain pressure. The vacuum-evacuated silicone rubber is then directly and evenly applied to the bonding surfaces of two loading metal cylindrical clamps. After standing for a period of time, the two bonding surfaces are joined together and placed on the gravity loading clamp 9, with the placement plane at an angle of 59–61° to the bottom surface, preferably 60°, so that the extension direction of the strip groove 10 on it forms an angle of 59–61° with the horizontal plane. Figure 3As shown. In some alternative embodiments, multiple specimen assemblies can be placed on the placement surface simultaneously. The gravity-loading fixture containing the specimens is placed at the temperature specified in the material specification for vulcanization. Throughout the vulcanization process, the specimen assemblies placed in the gravity-loading fixture should maintain axial coaxiality. In some alternative embodiments, after vulcanization, all excess and residual silicone rubber around the bonding area should be carefully removed. The bonded specimen assembly should meet the following requirements. Figure 1 Requirements.

[0033] This application simplifies the sample preparation method, reduces the connection structure of the sample fixture, reduces the number of parts, simplifies the preparation process, improves the overall sample preparation and assembly efficiency, and reduces manufacturing and measurement errors; at the same time, it fully utilizes the weight reduction advantages of composite materials. This application can be applied to the adhesive strength testing of liquid rubber materials for engines, and can also be extended to the adhesive strength testing of other materials. Its application prospects are broad, and it has significant social, military, and economic benefits.

[0034] Although this application has been described in detail above with general descriptions and specific embodiments, some modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, such modifications or improvements made without departing from the spirit of this application are all within the scope of protection claimed in this application.

Claims

1. A method for testing the adhesive strength of liquid silicone rubber, characterized in that, include: Step S1: Mix the components of the liquid silicone rubber evenly according to the set ratio; Step S2: Place the mixed liquid silicone rubber solution in a vacuum device and evacuate it under a set pressure; Step S3: Apply the vacuum-sealed liquid silicone rubber adhesive to the bonding surfaces of the two metal cylindrical clamps. One end of each metal cylindrical clamp has a bonding surface, and the other end is provided with an external thread that can be adapted to connect a tensile load loading device. Step S4: Join the adhesive surfaces of the two metal cylindrical clamps together to form a sample assembly; Step S5: Place multiple sample assemblies on a gravity loading fixture, which has multiple inclined slots, each slot being adapted to accommodate one sample assembly. Step S6: Place the gravity loading fixture containing the sample assembly into the vulcanization environment for vulcanization treatment at the set temperature. Step S7: Connect each metal cylindrical clamp of the sample assembly to a tensile load loading device, apply tensile force to the mutually bonded metal cylindrical clamps based on the tensile load loading device, and test the bonding strength of the liquid silicone rubber. In step S3, the metal cylindrical clamp is made of titanium alloy, and the size of the metal cylindrical clamp is set such that the ratio of its length to its diameter is between 1 and 2, and the length of the external thread is not less than 20 mm. In step S5, the gravity loading fixture is configured such that when the gravity loading fixture is stably installed on the test bench plane, the extension direction of the strip groove makes an angle of 59~61° with the horizontal plane. After step S6, the process further includes cleaning the residual silicone rubber around the adhesive surface of the metal cylindrical clamp.

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