Thermotropic shape memory epoxy resin material based on polycaprolactone and preparation method thereof

Abstract

The invention provides a thermotropic shape memory epoxy resin material based on polycaprolactone and a preparation method thereof, and belongs to the field of shape memory polymers. According to the preparation method of the thermotropic shape memory epoxy resin material based on polycaprolactone, epoxy resin monomers and polycaprolactone are adopted as main raw materials, the main raw materials and a curing agent are guided into a mold together for curing, and the thermotropic shape memory epoxy resin material is obtained through temperature control in the curing process. The thermotropic shape memory epoxy resin material prepared by the invention has better mechanical properties, and industrial production can be realized.

Description

Technical Field

[0001] The invention belongs to the field of shape memory polymers, and in particular relates to a thermotropic shape memory epoxy resin material based on polycaprolactone and a preparation method thereof. Background Art

[0002] In the field of modern materials science and engineering, with the continuous advancement of technology and the changing application needs, functional materials with special properties have gradually become a hot topic of research. Among them, shape memory functional materials, as a type of intelligent material that can restore its original shape when external conditions change, have shown great application potential in aerospace, medical devices, intelligent structures, flexible electronics, robotics and other fields due to their unique adaptability and self-healing properties. Shape memory materials can be divided into shape memory alloys, shape memory polymers and shape memory ceramics according to their basic materials.

[0003] Shape memory polymer materials have gradually attracted widespread attention in the above applications because of their advantages such as good processability, adjustability, light weight, corrosion resistance, and controllable thermal response characteristics. In particular, shape memory materials with resin materials as the matrix have high processing flexibility and low production cost based on the shape memory effect, and have become one of the important research directions of shape memory functional materials. However, the tensile strength of common shape memory resin materials is relatively low, which limits their application in various fields. Among the patents for shape memory epoxy resin materials that can be queried, the highest tensile strength is 54.49MPa (Chinese patent CN118515851B). Therefore, it is of great significance to prepare thermotropic shape memory epoxy resin materials with high tensile strength. Summary of the invention

[0004] The present invention is made to achieve the above-mentioned purpose, and its purpose is to provide a thermotropic shape memory epoxy resin material based on polycaprolactone and a preparation method thereof.

[0005] The present invention provides a method for preparing a thermotropic shape memory epoxy resin material based on polycaprolactone, which has the following characteristics and comprises the following steps: S10, after adding a polycaprolactone material and an epoxy resin monomer, standing at a temperature T1 until the polycaprolactone material is completely melted, to obtain a first mixed liquid, wherein the content of the polycaprolactone material in the first mixed liquid 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 mixed liquid for a period of time , cool to 40°C and continue stirring for a period of time to obtain a second mixed liquid, which is a mixture of polycaprolactone material and epoxy resin monomer; S30, add a curing agent to the second mixed liquid and stir for a period of time to obtain a third mixed liquid; S40, heat the third mixed liquid to 70°C~85°C and continue stirring for a period of time to obtain a fourth mixed liquid; S50, pour the fourth mixed liquid into a mold, and cure it at 110°C~130°C for 4h~6h, then cool it naturally and demold it to obtain a thermotropic shape memory epoxy resin material based on polycaprolactone.

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

[0007] In the preparation method of the thermotropic shape memory epoxy resin material based on polycaprolactone provided by the present invention, it can also have the following characteristics: wherein, in step S10, when the content of polycaprolactone material in the first mixed liquid 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 the thermotropic shape memory epoxy resin material based on polycaprolactone provided by the present invention may also have the following characteristics: wherein, in step S10, the polycaprolactone material is 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 the thermotropic shape memory epoxy resin material based on polycaprolactone provided by the present invention may also have the following characteristics: wherein, in step S10, the epoxy resin monomer includes any one or more of bisphenol A epoxy resin, bisphenol F epoxy resin or bisphenol S epoxy resin.

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

[0011] The method for preparing the thermotropic shape memory epoxy resin material based on polycaprolactone provided by the present invention may also have the following characteristics: 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).

[0012] The method for preparing the 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 less than the stirring rate in step S20 to reduce bubbles.

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

[0014] The present invention also provides a thermotropic shape memory epoxy resin material based on polycaprolactone, which has the following characteristics: it is prepared by any of the aforementioned methods for preparing a thermotropic shape memory epoxy resin material based on polycaprolactone, wherein the thermotropic shape memory epoxy resin material based on polycaprolactone changes from its original shape to a new shape under the action of a continuous and stable external force at a deformation temperature, and maintains the new shape after the external force is removed after cooling to room temperature; when the thermotropic shape memory epoxy resin material based on polycaprolactone with a new shape is placed at a deformation temperature, it returns to its original shape, when the content of the polycaprolactone material in the first mixed liquid is 5wt% to 20wt%, the deformation temperature is 60°C to 150°C, and the tensile strength of the thermotropic shape memory epoxy resin material based on polycaprolactone at room temperature is 45.5MPa to 81.5MPa, and the bending strength is 78.4 to 140.7MPa.

[0015] Functions and Effects of the Invention

[0016] The preparation method of the thermotropic shape memory epoxy resin material based on polycaprolactone of the present invention can ensure that the prepared shape memory epoxy resin material has high tensile and flexural strengths and maintains good shape memory performance by controlling the types and amounts of the polycaprolactone material, epoxy resin monomer and curing agent as well as the process parameters of each step, so that the material can achieve a better comprehensive effect in terms of mechanical properties and shape memory function, so that it has better application potential in fields with high requirements on material performance and requiring shape memory function, and at the same time provides an effective technical reference for the preparation of related shape memory epoxy resin materials, which is helpful to promote the development and optimization of the preparation technology of such materials.

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

[0018] The shape memory epoxy resin material prepared by the preparation method of the thermotropic shape memory epoxy resin material based on polycaprolactone of the present invention realizes the shape memory function, can change the shape at the deformation temperature and be fixed after cooling, and can restore the original shape when heated again, which makes it applicable to aerospace, medical equipment, intelligent structure, flexible electronics, robotics and other fields, such as the manufacture of adaptive wings, intelligent brackets, deformable building components, flexible electronic components, robotic adaptive limbs, etc.

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

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

[0021] The polycaprolactone-based thermotropic shape memory epoxy resin material of the present invention has controllable thermal response characteristics, and the deformation temperature is between 60°C and 150°C. It can trigger and recover the shape memory function in a wide temperature range, and can control the shape change according to the temperature requirements of different application environments. It is suitable for scenarios where temperature changes frequently or precise temperature control of shape changes is required, and improves the stability, reliability and accuracy of related equipment, structures or instruments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a flowchart of 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 are tensile stress-strain curves of Sample 1, Sample 2, Sample 3 and Sample 4 of the embodiments of the present invention at room temperature;

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

[0025] Figure 4 1 is a SEM image of the tensile fracture surface of sample 1, sample 2, sample 3 and sample 4 of the embodiment of the present invention;

[0026] Figure 5 These are shape memory electronic digital photos of Sample 1, Sample 2, Sample 3 and Sample 4 according to the embodiments of the present invention. DETAILED DESCRIPTION

[0027] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the following embodiments and the accompanying drawings specifically illustrate a thermotropic shape memory epoxy resin material based on polycaprolactone and a preparation method thereof of the present invention.

[0028] <Example>

[0029] Figure 1 It is a flowchart of 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, comprising the following steps:

[0031] S10, respectively add polycaprolactone material and epoxy resin monomer into a beaker (wherein the polycaprolactone material accounts for 5wt% to 20wt% of the total feed amount), and place in a 60° C. water bath until the polycaprolactone material is completely melted to obtain a first mixed solution.

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

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

[0034] S20, stirring the first mixed solution in a 60° C. water bath at a rotation speed of 600 rpm for 30 min, lowering the water bath temperature to 40° C. and continuing stirring for 30 min to obtain a second mixed solution.

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

[0036] S30, adding EK3402 as a curing agent into the second mixed liquid and continuing to stir at a rotation speed of 200 rpm for 30 minutes in a 40° C. water bath to obtain a third mixed liquid.

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

[0038] S40, heating the third mixed solution to 70° C. in a water bath and continuing stirring for 3 h to obtain a fourth mixed solution.

[0039] S50, pouring the fourth mixed liquid into an alloy mold having a polytetrafluoroethylene coating, and curing it at 120° C. for 5 hours, then naturally cooling it to room temperature and demolding it to obtain a thermotropic shape memory epoxy resin material based on polycaprolactone.

[0040] The present embodiment further 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 the present embodiment.

[0041] In this embodiment, a total of 4 portions of thermotropic shape memory epoxy resin materials based on polycaprolactone were prepared, which were respectively recorded as sample 1, sample 2, sample 3 and sample 4.

[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 5wt%, 10wt%, 15wt% and 20wt% of the total feed amount, respectively.

[0043] Figure 2 1 is the tensile stress-strain curve of Sample 1, Sample 2, Sample 3 and Sample 4 of the embodiment of the present invention at room temperature.

[0044] like Figure 2 As shown, the tensile strengths of the four polycaprolactone-based thermotropic shape memory epoxy resin materials (sample 1, sample 2, sample 3 and sample 4) 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 54.49 MPa of the shape memory epoxy resin material in the prior art (patent number CN118515851B); the tensile strength of sample 4 is close to 54.49 MPa of the shape memory epoxy resin material in the prior art.

[0046] Figure 31 and 2 are bending stress-strain curves of Samples 1, 2, 3 and 4 of the embodiments of the present invention at room temperature.

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

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

[0049] Figure 4 1 and 2 are SEM images of tensile fracture surfaces of Sample 1, Sample 2, Sample 3, and Sample 4 according to the examples of the present invention.

[0050] like Figure 4 As shown in the figure, from sample 1 to sample 3, as the polycaprolactone content increases, the number of filamentous pullouts on the fracture surface of the sample increases gradually, indicating that the polycaprolactone in the sample is pulled out as a discontinuous phase when the sample is broken. The fracture surface of sample 4 presents a smooth interface. At this time, as the polycaprolactone content increases, it has a better interface bonding with the epoxy resin, which gradually strengthens the interaction between the two phases, increases the overall consistency of the material and the mutual locking effect, and prevents the pullout of a single phase.

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

[0052] like Figure 5 As shown, Sample 1, Sample 2, Sample 3 and Sample 4 are loaded with continuous and stable external forces at 110°C, 90°C, 80°C and 70°C, respectively, so that they change from their original shapes to new shapes, and the new shapes are still maintained after the external force is removed after cooling to room temperature (25°C); the polycaprolactone-based thermotropic shape memory epoxy resin materials (Sample 1, Sample 2, Sample 3 and Sample 4) with new shapes are placed at their corresponding deformation temperatures (110°C, 90°C, 80°C, 70°C), respectively, and they all return to their original shapes.

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

[0054] In addition, when the polycaprolactone content exceeds 20wt%, the tensile strength of the material begins to decrease. When the content is 25wt%, the tensile strength of the material is 21.3MPa. When the content is 30wt%, the tensile strength of the material is 10.5MPa, but the material still has good shape memory properties. For some specific application fields of shape memory materials, when the mechanical properties of the material are not required to be high, the material still has broad application prospects.

[0055] Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing a thermotropic shape memory epoxy resin material based on polycaprolactone, characterized in that: The following steps are involved: S10, adding polycaprolactone material and epoxy resin monomer, and standing at temperature T1 until the polycaprolactone material is completely melted to obtain a first mixed solution, Wherein, the content of the polycaprolactone material in the first mixed liquid 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, stirring the first mixed solution for a period of time, cooling the temperature to 40° C. and continuing to stir for a period of time to obtain a second mixed solution, wherein the second mixed solution is a mixed solution of a polycaprolactone material and an epoxy resin monomer; S30, adding a curing agent into the second mixed liquid and stirring for a period of time to obtain a third mixed liquid; S40, heating the third mixed solution to 70° C. to 85° C. and continuing stirring for a period of time to obtain a fourth mixed solution; S50, pouring the fourth mixed liquid into a mold, curing it at 110° C. to 130° C. for 4 h to 6 h, then naturally cooling it and demolding it to obtain a thermotropic shape memory epoxy resin material based on polycaprolactone.

2. The method for preparing a thermotropic shape memory epoxy resin material based on polycaprolactone according to claim 1, characterized in that: in, In step S10, T1 is 60°C to 70°C.

3. The method for preparing a thermotropic shape memory epoxy resin material based on polycaprolactone according to claim 1, characterized in that: in, In step S10, the content of the polycaprolactone material in the first mixed solution is 5wt% to 20wt%.

4. The method for preparing a thermotropic shape memory epoxy resin material based on polycaprolactone according to claim 1, characterized in that: in, In step S10, the polycaprolactone material is a polycaprolactone of a single molecular weight or a mixture of polycaprolactones of different molecular weights. The molecular weight range of polycaprolactone is 500-4000.

5. The method for preparing a thermotropic shape memory epoxy resin material based on polycaprolactone according to claim 1, characterized in that: in, In step S10, the epoxy resin monomer includes any one or more of bisphenol A epoxy resin, bisphenol F epoxy resin or bisphenol S epoxy resin.

6. The method for preparing a thermotropic shape memory epoxy resin material based on polycaprolactone according to claim 1, characterized in that: in, In step S30, the curing agent includes any one or more of PACM, AIBN or EK3402.

7. The method for preparing a thermotropic shape memory epoxy resin material based on polycaprolactone according to claim 1, characterized in that: in, The mass ratio of the epoxy resin monomer in step S10 to the curing agent in step S30 is 1:(0.2-0.3).

8. The method for preparing a thermotropic shape memory epoxy resin material based on polycaprolactone according to claim 1, characterized in that: in, The stirring rate in step S30 is lower than the stirring rate in step S20.

9. The method for preparing a thermotropic shape memory epoxy resin material based on polycaprolactone according to claim 1, characterized in that: in, In step S50, a polytetrafluoroethylene coating is provided on the surface of the molding cavity of the mold.

10. A thermotropic shape memory epoxy resin material based on polycaprolactone, characterized in that: The thermotropic shape memory epoxy resin material based on polycaprolactone is prepared by the preparation method of any one of claims 1 to 9, The polycaprolactone-based thermotropic shape memory epoxy resin material changes from its original shape to a new shape under the action of a continuous and stable external force at a deformation temperature, and maintains the new shape after the external force is removed after cooling to room temperature; the polycaprolactone-based thermotropic shape memory epoxy resin material having a new shape is placed at a deformation temperature, and then it returns to its original shape. When the content of the polycaprolactone material in the first mixed liquid is 5wt% to 20wt%, the deformation temperature is 60°C to 150°C, and the tensile strength of the polycaprolactone-based thermotropic shape memory epoxy resin material at room temperature is 45.5MPa to 81.5MPa, and the bending strength is 78.4 to 140.7MPa.

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