A polycaprolactone-based thermotropic shape memory epoxy resin material and a preparation method thereof

Abstract

The application provides a polycaprolactone-based thermotropic shape memory epoxy resin material and a preparation method thereof, and belongs to the field of shape memory polymers. The preparation method of the polycaprolactone-based thermotropic shape memory epoxy resin material adopts epoxy resin monomers and polycaprolactone as main raw materials, and the main raw materials are introduced into a mold together with a curing agent for curing. Through temperature control during the curing process, the thermotropic shape memory epoxy resin material is obtained. The thermotropic shape memory epoxy resin material prepared by the application has good mechanical properties and can realize industrialized production.

Description

Technical Field

[0001] This invention belongs to the field of shape memory polymers, specifically relating to a thermotropic shape memory epoxy resin material based on polycaprolactone and its preparation method. Background Technology

[0002] In the field of modern materials science and engineering, with the continuous advancement of technology and the ever-changing application demands, functional materials with special properties have gradually become a research hotspot. Among them, shape memory functional materials, as a class of smart materials capable of recovering their original shape when external conditions change, have shown great application potential in aerospace, medical devices, smart structures, flexible electronics, robotics, and many other fields due to their unique adaptive and self-healing properties. Shape memory materials can be classified into shape memory alloys, shape memory polymers, and shape memory ceramics, depending on their base materials.

[0003] Shape memory polymer materials have gradually attracted widespread attention in the aforementioned applications due to their advantages such as good processability, adjustability, lightweight, corrosion resistance, and controllable thermal response characteristics. In particular, shape memory materials using resin as the matrix, based on the shape memory effect, possess high processing flexibility and low production costs, making them one of the important directions in shape memory functional material research. However, the low tensile strength of commonly used shape memory resin materials currently limits their application in various fields. Among the shape memory epoxy resin material patents currently available, the highest tensile strength is 54.49 MPa (Chinese Patent CN118515851B). Therefore, the preparation of high-tensile-strength thermotropic shape memory epoxy resin materials is of great significance. Summary of the Invention

[0004] The present invention is made to achieve the above-mentioned objectives, and aims to provide a thermotropic shape memory epoxy resin material based on polycaprolactone and a method for preparing the same.

[0005] This invention provides a method for preparing a thermotropic shape memory epoxy resin material based on polycaprolactone, characterized by the following steps: S10, after feeding polycaprolactone material and epoxy resin monomer, the mixture is allowed to stand at temperature T1 until the polycaprolactone material is completely melted to obtain a first mixture, wherein the content of polycaprolactone material in the first mixture is 5wt% to 40wt%, T1 is not less than the melting temperature of the polycaprolactone material, and T1 is less than the thermosetting temperature of the epoxy resin monomer; S20, after stirring the first mixture for a period of time... The mixture is cooled to 40°C and stirred for a period of time to obtain a second mixture, which is a mixture of polycaprolactone material and epoxy resin monomer; S30, a curing agent is added to the second mixture and stirred for a period of time to obtain a third mixture; S40, the third mixture is heated to 70°C~85°C and stirred for a period of time to obtain a fourth mixture; S50, the fourth mixture is poured into a mold and cured at 110°C~130°C for 4h~6h, then naturally cooled and demolded to obtain a thermotropic shape memory epoxy resin material based on polycaprolactone.

[0006] The method for preparing thermotropic shape memory epoxy resin material based on polycaprolactone provided by the present invention may also have the following feature: in step S10, T1 is 60℃~70℃.

[0007] The method for preparing thermotropic shape memory epoxy resin material based on polycaprolactone provided by the present invention may also have the following characteristics: in step S10, when the content of polycaprolactone material in the first mixture is 5wt% to 20wt%, it can ensure that the material has both good shape memory function and excellent mechanical properties.

[0008] The method for preparing thermotropic shape memory epoxy resin material based on polycaprolactone provided by the present invention may also have the following feature: in step S10, the polycaprolactone material is a polycaprolactone of a single molecular weight or a mixture of polycaprolactones of different molecular weights, and the molecular weight range of the polycaprolactone is 500 to 4000.

[0009] The method for preparing thermotropic shape memory epoxy resin material based on polycaprolactone provided by the present invention may also have the following feature: wherein, in step S10, the epoxy resin monomer includes any one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin, or bisphenol S type epoxy resin.

[0010] The method for preparing thermotropic shape memory epoxy resin material based on polycaprolactone provided by the present invention may also have the following feature: wherein, in step S30, the curing agent includes any one or more of PACM, AIBN or EK3402.

[0011] The method for preparing thermotropic shape memory epoxy resin material based on polycaprolactone provided by the present invention may also have the following feature: wherein the mass ratio of epoxy resin monomer in step S10 to curing agent in step S30 is 1:(0.2~0.3).

[0012] The method for preparing thermotropic shape memory epoxy resin material based on polycaprolactone provided by the present invention may also have the following feature: wherein the stirring rate in step S30 is lower than the stirring rate in step S20, so as to reduce bubbles.

[0013] The method for preparing thermotropic shape memory epoxy resin material based on polycaprolactone provided by the present invention may also have the following feature: in step S50, the surface of the molding cavity of the mold is provided with a polytetrafluoroethylene coating to facilitate demolding.

[0014] This invention also provides a thermotropic shape memory epoxy resin material based on polycaprolactone, characterized by being prepared by any of the aforementioned methods for preparing thermotropic shape memory epoxy resin materials based on polycaprolactone. Specifically, the thermotropic shape memory epoxy resin material based on polycaprolactone changes its original shape to a new shape under continuous and stable external force at a deformation temperature, and retains the new shape after the external force is removed upon cooling to room temperature. When the thermotropic shape memory epoxy resin material based on polycaprolactone with the new shape is placed at a deformation temperature, it recovers to its original shape. When the polycaprolactone content in the first mixture is 5wt% to 20wt%, the deformation temperature is 60℃ to 150℃. The thermotropic shape memory epoxy resin material based on polycaprolactone has a tensile strength of 45.5MPa to 81.5MPa and a flexural strength of 78.4 to 140.7MPa at room temperature.

[0015] The role and effect of invention

[0016] The method for preparing thermotropic shape memory epoxy resin materials based on polycaprolactone of this invention, by controlling the types and amounts of polycaprolactone, epoxy resin monomers, curing agents, and process parameters of each step, can ensure that the prepared shape memory epoxy resin material has high tensile and flexural strength while maintaining good shape memory properties. This results in a better overall effect in terms of mechanical properties and shape memory function, making it more applicable in fields requiring high material performance and shape memory functionality. Furthermore, it provides an effective technical reference for the preparation of related shape memory epoxy resin materials, contributing to the development and optimization of such material preparation technologies.

[0017] The selection of temperature T1 in step S10 is the key point of this invention. Temperature T1 needs to ensure that polycaprolactone can be mixed with epoxy monomer in the molten state without causing stratification between the two phases of polycaprolactone and epoxy monomer.

[0018] The shape memory epoxy resin material prepared by the method of preparing thermotropic shape memory epoxy resin material based on polycaprolactone of the present invention achieves shape memory function. It can change shape at the deformation temperature and fix it after cooling. It can restore the original shape when heated again. This enables it to be used in many fields such as aerospace, medical devices, smart structures, flexible electronics, and robotics, such as the manufacture of adaptive wings, smart brackets, deformable building components, flexible electronic components, and adaptive robot limbs.

[0019] The thermotropic shape memory epoxy resin material based on polycaprolactone of this invention effectively improves material performance and solves the problem of low tensile strength of existing common shape memory resin materials. Its tensile strength can reach up to 81.5 MPa, which far exceeds that of polyurethane, polyester, polyolefin and other series of shape memory resin products. It can meet more application scenarios with high mechanical performance requirements and expand the application range of shape memory epoxy resin materials.

[0020] In terms of performance, the thermotropic shape memory epoxy resin material based on polycaprolactone of the present invention inherits the good processability of resin materials, has a relatively simple preparation method, can be manufactured into products of different shapes and sizes using a variety of molding processes, and has a low production cost, which is conducive to large-scale production and promotion and improves the market competitiveness of products.

[0021] The thermotropic shape memory epoxy resin material based on polycaprolactone of the present invention has controllable thermal response characteristics, with a deformation temperature between 60°C and 150°C. It can achieve shape memory function triggering and recovery over a wide temperature range, and can control shape changes according to the temperature requirements of different application environments. It is suitable for scenarios with frequent temperature changes or requiring precise temperature control of shape changes, thereby improving the stability, reliability and accuracy of related equipment, structures or instruments. Attached Figure Description

[0022] Figure 1 This is a flowchart illustrating a method for preparing a thermotropic shape memory epoxy resin material based on polycaprolactone, according to an embodiment of the present invention.

[0023] Figure 2 These are the tensile stress-strain curves of samples 1, 2, 3, and 4 from embodiments of the present invention at room temperature.

[0024] Figure 3 These are the bending stress-strain curves of samples 1, 2, 3, and 4 from embodiments of the present invention at room temperature.

[0025] Figure 4 These are SEM images of the tensile fracture surfaces of samples 1, 2, 3, and 4, which are embodiments of the present invention.

[0026] Figure 5 These are shape memory electronic digital photographs of Sample 1, Sample 2, Sample 3, and Sample 4, which are embodiments of the present invention. Detailed Implementation

[0027] To make the technical means, creative features, objectives and effects of the present invention easy to understand, the following embodiments, in conjunction with the accompanying drawings, specifically illustrate a thermotropic shape memory epoxy resin material based on polycaprolactone and its preparation method.

[0028] <Example>

[0029] Figure 1 This is a flowchart illustrating a method for preparing a thermotropic shape memory epoxy resin material based on polycaprolactone, according to an embodiment of the present invention.

[0030] like Figure 1 As shown, this embodiment provides a method for preparing a thermotropic shape memory epoxy resin material based on polycaprolactone, including the following steps:

[0031] S10, add polycaprolactone material and epoxy resin monomer (polycaprolactone material accounts for 5wt% to 20wt% of the total feed) to a beaker, and let it stand in a water bath at 60°C until the polycaprolactone material is completely melted to obtain the first mixture.

[0032] The polycaprolactone material is either a single molecular weight polycaprolactone or a mixture of polycaprolactones with different molecular weights (ranging from 500 to 4000). Specifically, in this embodiment, a polycaprolactone with a molecular weight of 2000 is selected.

[0033] The epoxy resin monomer includes any one or more of bisphenol A type epoxy resin monomers, bisphenol F type epoxy resin monomers, or bisphenol S type epoxy resin monomers. Specifically, in this embodiment, bisphenol F type epoxy resin monomers (Epon-862, Hexion) are selected.

[0034] S20, after stirring the first mixture in a 60°C water bath at 600 rpm for 30 minutes, lower the water bath temperature to 40°C and continue stirring for 30 minutes to obtain the second mixture.

[0035] The second mixture is a liquid obtained by fully mixing polycaprolactone material and epoxy resin monomer.

[0036] S30, add EK3402 as a curing agent to the second mixture and continue stirring at 200 rpm for 30 minutes in a 40°C water bath to obtain the third mixture.

[0037] In this step, the amount of EK3402 added is such that the mass ratio of epoxy resin monomer to EK3402 in the second mixture is 100:26.5.

[0038] S40, the third mixture is heated to 70°C in a water bath and stirred for 3 hours to obtain the fourth mixture.

[0039] S50, the fourth mixture is poured into an alloy mold with a polytetrafluoroethylene coating, cured at 120°C for 5 hours, and then naturally cooled to room temperature and demolded to obtain a thermotropic shape memory epoxy resin material based on polycaprolactone.

[0040] This embodiment also provides a thermotropic shape memory epoxy resin material based on polycaprolactone, which is prepared by the preparation method of the thermotropic shape memory epoxy resin material based on polycaprolactone provided in this embodiment.

[0041] In this embodiment, a total of four thermotropic shape memory epoxy resin materials based on polycaprolactone were prepared, which are referred to as Sample 1, Sample 2, Sample 3 and Sample 4, respectively.

[0042] The preparation processes of Sample 1, Sample 2, Sample 3 and Sample 4 are generally similar, with the only difference being that in step S10 of the preparation process of Sample 1, Sample 2, Sample 3 and Sample 4, the polycaprolactone material accounts for 5 wt%, 10 wt%, 15 wt% and 20 wt% of the total feed, respectively.

[0043] Figure 2 These are the tensile stress-strain curves of samples 1, 2, 3 and 4 at room temperature, which are embodiments of the present invention.

[0044] like Figure 2 As shown, the tensile strengths of the four thermotropic shape memory epoxy resin materials (sample 1, sample 2, sample 3 and sample 4) based on polycaprolactone prepared in this embodiment are 81.5 MPa, 79.5 MPa, 70.8 MPa and 48.9 MPa, respectively.

[0045] Among them, the tensile strength of samples 1, 2 and 3 is significantly higher than that of the existing shape memory epoxy resin material (patent number CN118515851B) at 54.49 MPa; the tensile strength of sample 4 is close to that of the existing shape memory epoxy resin material at 54.49 MPa.

[0046] Figure 3These are the bending stress-strain curves of samples 1, 2, 3 and 4 at room temperature, which are embodiments of the present invention.

[0047] like Figure 3 As shown, the flexural strengths of the four thermotropic shape memory epoxy resin materials (sample 1, sample 2, sample 3 and sample 4) based on polycaprolactone prepared in this embodiment are 142 MPa, 140 MPa, 121.8 MPa and 88.1 MPa, respectively.

[0048] Among them, the bending strength of Sample 1 and Sample 2 is significantly higher than that of the shape memory epoxy resin material in the prior art (patent number CN118515851B); the bending strength of Sample 3 is slightly higher than that of the shape memory epoxy resin material in the prior art (120.5 MPa).

[0049] Figure 4 These are SEM images of the tensile fracture surfaces of samples 1, 2, 3, and 4, which are embodiments of the present invention.

[0050] like Figure 4 As shown, from samples 1 to 3, the amount of filamentous pull-out material on the fracture surface gradually increased with the increase of polycaprolactone content, indicating that polycaprolactone, as a discontinuous phase, was pulled out during sample fracture. Sample 4, on the other hand, exhibited a smooth interface on its fracture surface. In this case, with the increase of polycaprolactone content, it had better interfacial bonding with the epoxy resin, gradually enhancing the interaction between the two phases, increasing the overall consistency and interlocking effect of the material, and preventing the pull-out of individual phases.

[0051] Figure 5 These are shape memory electronic digital photographs of Sample 1, Sample 2, Sample 3, and Sample 4, which are embodiments of the present invention.

[0052] like Figure 5 As shown, samples 1, 2, 3, and 4 were subjected to continuous and stable external forces at 110℃, 90℃, 80℃, and 70℃, respectively, causing them to change from their original shapes to new shapes. After cooling to room temperature (25℃) and removing the external forces, they retained their new shapes. When the thermotropic shape memory epoxy resin materials based on polycaprolactone (samples 1, 2, 3, and 4) with the new shapes were placed at their corresponding deformation temperatures (110℃, 90℃, 80℃, and 70℃), they all returned to their original shapes.

[0053] like Figure 5 As shown, the four thermotropic shape memory epoxy resin materials (sample 1, sample 2, sample 3 and sample 4) based on polycaprolactone prepared in this embodiment all have good shape memory function.

[0054] Furthermore, the tensile strength of the material begins to decrease when the polycaprolactone content exceeds 20 wt%. At 25 wt%, the tensile strength is 21.3 MPa, and at 30 wt%, it is 10.5 MPa. However, the material still exhibits good shape memory properties. For certain specific shape memory material applications where high mechanical property requirements are not necessary, this material still holds broad application prospects.

[0055] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a polycaprolactone-based thermotropic shape memory epoxy resin material, characterized by, The method comprises the following steps: S10, after the polycaprolactone material and epoxy resin monomer are put into, standing at temperature T1 until the polycaprolactone material is completely melted, to obtain a first mixed solution, Wherein, the polycaprolactone material content in the first mixed solution is 5wt%-20wt%, T1 is not less than the melting temperature of the polycaprolactone material, and T1 is less than the heat solidification temperature of the epoxy resin monomer, T1 is 60℃-70℃, the polycaprolactone material is polycaprolactone with a molecular weight range of 500-4000, and the epoxy resin monomer includes any one or more of bisphenol A type epoxy resin, bisphenol F type epoxy resin or bisphenol S type epoxy resin; S20, after the first mixed solution is stirred for a period of time, it is cooled to 40℃ and continues to be stirred for a period of time to obtain a second mixed solution, which is a mixed solution of polycaprolactone material and epoxy resin monomer; S30, the curing agent is put into the second mixed solution and stirred for a period of time to obtain a third mixed solution; S40, the third mixed solution is heated to 70℃-85℃ and continues to be stirred for a period of time to obtain a fourth mixed solution; S50, the fourth mixed solution is poured into a mold, and after being cured at 110℃-130℃ for 4h-6h, it is naturally cooled and demolded to obtain a polycaprolactone-based thermal type shape memory epoxy resin material, Wherein, the polycaprolactone-based thermal type shape memory epoxy resin material is changed from the original shape to a new shape under the action of a continuous and stable external force at the deformation temperature, and still keeps the new shape after cooling to room temperature and removing the external force, When the polycaprolactone-based thermal type shape memory epoxy resin material with the new shape is placed at the deformation temperature again, it returns to the original shape, The deformation temperature is 60℃-150℃, The tensile strength of the polycaprolactone-based thermal type shape memory epoxy resin material at room temperature is 45.5MPa-81.5MPa, and the bending strength is 78.4MPa-140.7MPa.

2. The preparation method of the polycaprolactone-based thermal type shape memory epoxy resin material according to claim 1, characterized in that: wherein In step S30, the curing agent includes any one or more of PACM, AIBN or EK3402.

3. The preparation method of the polycaprolactone-based thermal type shape memory epoxy resin material according to claim 1, characterized in that: wherein The mass ratio of the epoxy resin monomer in step S10 to the curing agent in step S30 is 1:(0.2-0.3).

4. The preparation method of the polycaprolactone-based thermal type shape memory epoxy resin material according to claim 1, characterized in that: wherein The stirring rate in step S30 is less than the stirring rate in step S20.

5. The preparation method of the polycaprolactone-based thermal type shape memory epoxy resin material according to claim 1, characterized in that: wherein In step S50, the forming cavity surface of the mold is provided with a polytetrafluoroethylene coating.

6. A polycaprolactone-based thermotropic shape memory epoxy resin material, characterized by, Prepared by the preparation method of the polycaprolactone-based thermal type shape memory epoxy resin material according to any one of claims 1-5.

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