An SMA material, its preparation method and application

Abstract

The present invention discloses an SMA material, its preparation method and application, belonging to the technical field of polymer materials; the SMA material provided by the present invention comprises the following components in parts by mass: 35-67 parts of SMA resin, 2-5 parts of toughening agent, 10-20 parts of glass fiber, 10-20 parts of glass microbead, and 1-6 parts of compatibility promoter; in the SMA material provided by the present invention, through the synergistic action of the self-made compatibility promoter, chopped glass fiber and glass microbeads within a specific particle size range, and in combination with the toughening agent, the dimensional shrinkage rate and anisotropy of the SMA material can be significantly enhanced, showing excellent dimensional stability; and on the basis of high dimensional stability, it also has excellent mechanical properties; in addition, the preparation method of the SMA material provided by the present invention is simple and easy for actual production.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and particularly relates to an SMA material, a preparation method thereof, and an application thereof. Background Art

[0002] The lightweighting of automobiles is to reduce the overall vehicle mass of automobiles as much as possible on the premise of ensuring strength and safety performance. Experiments have proved that when the overall vehicle weight of an automobile is reduced by 10%, the fuel efficiency can be increased by about 6%-8%. In the era of new energy vehicles, endurance is the key concern of everyone. Due to environmental protection and energy conservation needs, the lightweighting of automobiles has become a global trend in the development of automobiles. Specifically in terms of part design, the material selection concept of "replacing steel with plastic" has become an industry consensus. Replacing steel with plastic can significantly reduce the weight of parts. Traditional part skeletons are mostly made of metal materials and have gradually been replaced by glass fiber-reinforced thermoplastic polymer composites. The current commonly used thermoplastic matrix materials for reinforcing materials, such as polypropylene (PP), polyamide (PA), and polybutylene terephthalate (PBT), are all crystalline polymers. They have a strong crystallization tendency but a slow crystallization rate and an incomplete crystal structure. After the parts are formed, secondary crystallization will occur under the influence of heat, resulting in strong dimensional instability of the material. Glass fiber-reinforced ABS has low heat resistance and cannot be used in parts with high requirements for heat resistance temperature.

[0003] The SMA resin molecule structure has non-polar aromatic ring groups and polar anhydride groups. Therefore, it has good compatibility with polar materials such as minerals, glass fibers, and fillers. Therefore, it is an important modification direction of SMA. After modification, the mechanical properties of SMA are greatly improved, and phenomena such as stress stratification and cracking can also be improved. It can meet the requirements for high dimensional stability of automotive IP skeletons, sunroof frames, etc. CN1803912A describes a glass fiber-reinforced SMA resin for automotive instrument panels, which focuses on using a preferred toughening agent to improve the problem of insufficient impact resistance of the material, but does not involve the improvement of the material size effect; CN103819862A is an upgrade of the composite material processing method, using continuous long glass fibers to replace short cut glass fibers, thereby improving the mechanical property indexes such as material rigidity and impact resistance to a certain extent. However, in fact, the melt impregnation method used for long glass fibers is a weak shear processing method, and the bonding condition between the base material and the glass fiber is lower than that of the melt shear mixing method used for short glass fibers. Moreover, the glass fiber is prone to one-dimensional orientation characteristics during processing flow, and the degree of isotropy of the material is actually much lower than that of short glass fibers. The above inventions mainly focus on the conventional modification of glass fiber-reinforced SMA, and no one has been found to use the method of self-made modified glass fibers to improve the enhanced SMA to meet the requirements of high dimensions such as sunroof frames. Therefore, it is particularly necessary to develop a high dimensional stability enhanced SMA material to solve the current industry pain points. Summary of the Invention

[0004] The object of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide an SMA material with excellent mechanical properties and strong stability, as well as a preparation method and application thereof.

[0005] To achieve the above object, the technical solution adopted by the present invention is: an SMA material, the SMA material comprising the following components in parts by mass: 35 - 67 parts of SMA resin, 2 - 5 parts of toughening agent, 10 - 20 parts of glass fiber, 10 - 20 parts of glass microspheres, and 1 - 6 parts of compatibilization promoter;

[0006] The average length of the glass fiber is 3 - 4.5 mm;

[0007] The D50 particle size of the glass microspheres is 40 - 50 μm;

[0008] The compatibilization promoter is glycidyl methacrylate grafted branched styrene - acrylonitrile copolymer. In the glycidyl methacrylate grafted branched styrene - acrylonitrile copolymer, the mass percentage of branched styrene - acrylonitrile is 90 - 99%, the mass percentage of glycidyl methacrylate is 1 - 10%, and the epoxy value is 0.08 - 0.5 mol / 100 g.

[0009] In the SMA material provided by the present invention, by adding a compatibilization promoter with a certain epoxy value range, and the mass percentages of branched styrene - acrylonitrile and glycidyl methacrylate within a certain range, along with glass fibers of a specific length and glass microspheres within a specific particle size range, which interact synergistically, and in combination with a toughening agent, the dimensional shrinkage rate and isotropy of the SMA material can be significantly enhanced, demonstrating excellent dimensional stability; and on the basis of high dimensional stability, it also has excellent mechanical properties; specifically, the spherical structure of the glass microspheres added in the present invention determines its isotropic shrinkage in all directions. Selecting glass microspheres within the above - mentioned particle size range can reduce the flexural deformation and post - shrinkage of the product, and can also reduce the shrinkage rate and coefficient of thermal expansion, thereby further improving the dimensional stability of the product.

[0010] The mass percentages of the branched styrene-acrylonitrile copolymer and glycidyl methacrylate in the glycidyl methacrylate grafted branched styrene-acrylonitrile copolymer can achieve the effects of the present invention within the ranges given in the present invention. For example, the mass percentage of the branched styrene-acrylonitrile copolymer can be 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, and the corresponding mass percentage of glycidyl methacrylate can be 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%. Similarly, the epoxy value of the glycidyl methacrylate grafted branched styrene-acrylonitrile copolymer can achieve the effects of the present invention within the ranges given in the present invention. For example, the epoxy value can be 0.08 mol / 100 g, 0.1 mol / 100 g, 0.12 mol / 100 g, 0.14 mol / 100 g, 0.16 mol / 100 g, 0.18 mol / 100 g, 0.2 mol / 100 g, 0.22 mol / 100 g, 0.24 mol / 100 g, 0.26 mol / 100 g, 0.28 mol / 100 g, 0.3 mol / 100 g, 0.32 mol / 100 g, 0.34 mol / 100 g, 0.36 mol / 100 g, 0.38 mol / 100 g, 0.4 mol / 100 g, 0.42 mol / 100 g, 0.44 mol / 100 g, 0.46 mol / 100 g, 0.48 mol / 100 g, 0.5 mol / 100 g.

[0011] The test method for the epoxy value in the glycidyl methacrylate grafted branched styrene-acrylonitrile copolymer is carried out with reference to the method in GB / T 1677-2008.

[0012] The degree of branching of the glycidyl methacrylate grafted branched styrene-acrylonitrile copolymer is 15-90, and the effects of the present invention can be achieved within the ranges given in the present invention. For example, the degree of branching can be 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90.

[0013] As a preferred embodiment of the SMA material described in the present invention, the glycidyl methacrylate grafted branched styrene-acrylonitrile copolymer is prepared by mixing and extruding a branched styrene-acrylonitrile copolymer and glycidyl methacrylate, and the mass ratio of the branched styrene-acrylonitrile copolymer to glycidyl methacrylate is (80-99):(1-20).

[0014] The inventors' research found that when synthesizing the compatibility promoter using the above mass ratio, the epoxy value of the obtained product, as well as the mass percentages of the branched styrene-acrylonitrile copolymer and glycidyl methacrylate, are within the ranges defined in the present invention.

[0015] Preferably, the preparation method of the compatibility promoter is as follows: uniformly mixing the branched styrene-acrylonitrile copolymer and glycidyl methacrylate in a mass ratio of (80-99):(1-20), and then extruding to obtain the compatibility promoter.

[0016] Preferably, during the preparation process, an initiator, dicumyl peroxide, is also added and mixed with the branched styrene-acrylonitrile copolymer and glycidyl methacrylate. The addition amount of dicumyl peroxide is 0.08-0.5% of the total mass of the branched styrene-acrylonitrile copolymer and glycidyl methacrylate.

[0017] Preferably, in the preparation of the compatibility promoter, the parameters during the extrusion process are as follows: the screw length-diameter ratio is 48:1, the extrusion temperature is 170-200 °C, and the screw rotation speed is 200-400 rpm.

[0018] As a preferred embodiment of the SMA material of the present invention, in the SMA resin, the mass percentage of maleic anhydride is 6-25%.

[0019] Preferably, in the SMA resin, the mass percentage of maleic anhydride is 6-20%.

[0020] The inventors' research found that when the mass percentage of maleic anhydride in the SMA resin is selected to be 6-25%, especially 6-20%, the comprehensive performance of the obtained SMA material is better.

[0021] As a preferred embodiment of the SMA material of the present invention, the toughening agent is acrylonitrile-butadiene-styrene high rubber powder and / or ethylene-butyl acrylate-glycidyl methacrylate terpolymer.

[0022] Preferably, the above toughening agent can be well combined with other components, thereby making the stability and mechanical properties of the product more excellent.

[0023] As a preferred embodiment of the SMA material of the present invention, the average single filament diameter of the glass fiber is 10-15 μm.

[0024] Preferably, the average single filament diameter of the glass fiber is 10-13 μm.

[0025] The inventors' research found that when the average single filament diameter of the glass fiber is preferably 10-15 μm, especially when the average single filament diameter of the glass fiber is further preferably 10-13 μm, more excellent product stability can be achieved.

[0026] As a preferred embodiment of the SMA material of the present invention, the SMA material further comprises 0.5 - 2 parts of processing aids.

[0027] As a preferred embodiment of the SMA material of the present invention, the processing aids are antioxidants and / or lubricants.

[0028] Preferably, the antioxidant is at least one of hindered phenol antioxidants, thioester antioxidants, phosphite antioxidants, and hindered amine antioxidants; the lubricant is at least one of magnesium stearate, pentaerythritol stearate, ethylene bisstearamide, and polyethylene wax.

[0029] In addition, the present invention also provides a preparation method of an SMA material, the preparation method comprising the following steps: mixing the components except glass fiber in the formula evenly and adding them into the main feeder of a twin - screw extruder, then adding the glass fiber into the twin - screw extruder through a side feeder, and then melting, extruding, cooling, drying, and pelletizing to obtain the SMA material.

[0030] As a preferred embodiment of the preparation method of the present invention, during the extrusion process, the length - diameter ratio of the screw is (25 - 48):1, the vacuum degree is (-0.08) - (-0.1) MPa, the temperature of the feeding section is 200 - 220 °C, the temperature of the plasticizing section is 230 - 250 °C, the temperature of the post - homogenization extrusion section is 240 - 260 °C, and the screw speed is 400 - 600 rpm.

[0031] In addition, the present invention also provides an application of the SMA material in the preparation of automotive skeleton parts.

[0032] As a preferred embodiment of the application of the present invention, the automotive skeleton part includes any one of a sunroof skeleton, a central tunnel skeleton, an instrument panel skeleton, a pillar trim panel skeleton, and a tailgate skeleton.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] In an SMA material provided by the present invention, through the synergistic action of a self - made compatibility promoter, chopped glass fiber, and glass microbeads within a specific particle size range, and in combination with a toughening agent, the dimensional shrinkage rate and isotropy of the SMA material can be significantly enhanced, showing excellent dimensional stability; and on the basis of high dimensional stability, it also has excellent mechanical properties. Specifically, the flexural modulus of the SMA material provided by the present invention is above 7750 MPa, the impact strength is above 7.5 kJ / m 2 above, the linear expansion coefficient in the flow direction is below 17.5×10^-6 K -1 below, and the linear expansion coefficient in the direction perpendicular to the flow direction is below 39.4×10^-6 K-1 As follows. In addition, the preparation method of the SMA material provided by the present invention is simple and easy for actual production. Detailed implementation manners

[0035] To better illustrate the purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0036] The reagents, methods and equipment used in the present invention are all conventional reagents, methods and equipment in the art without special instructions; and the components used in the examples and comparative examples are the same without special instructions.

[0037] SMA resin 1: maleic anhydride content is 18±2wt%, SMA700, Huawen Chemical Industry;

[0038] SMA resin 2: maleic anhydride content is 8±2wt%, SMA800, Huawen Chemical Industry;

[0039] SMA resin 3: maleic anhydride content is 23±2wt%, SZ23110, Dutch Polyscope Company;

[0040] Toughening agent 1: acrylonitrile-butadiene-styrene high rubber powder, HR181, South Korea Kumho Petrochemical;

[0041] Toughening agent 2: ethylene-butyl acrylate-glycidyl methacrylate terpolymer, PTW, American DuPont Company;

[0042] Glass fiber 1: average fiber length 4.0mm, average single filament diameter 10μm, HMG436S-10-4.0, Taishan Fiberglass;

[0043] Glass fiber 2: average fiber length 4.5mm, average single filament diameter 13μm, ECS13-4.5-534A, Jushi Fiberglass;

[0044] Glass fiber 3: average fiber length 3.0mm, average single filament diameter 13μm, ECS13-3.0-T436W, Taishan Fiberglass;

[0045] Glass fiber 4: average fiber length 4.0mm, average single filament diameter 15μm, ECS15-4.0-T4356, Taishan Fiberglass;

[0046] Glass fiber 5: average fiber length 6mm, average single filament diameter 13μm, ECS-11-6.0, Yataida;

[0047] Glass microsphere 1: particle size D50 is 40, HN60, Hainuo Technology;

[0048] Glass microbead 2: The D50 particle size is 45, HN46, Hainuo Technology;

[0049] Glass microbead 3: The D50 particle size is 50, HN40, Hainuo Technology;

[0050] Glass microbead 4: The D50 particle size is 55, HN32, Hainuo Technology

[0051] Glass microbead 5: The D50 particle size is 35, HN38, Hainuo Technology;

[0052] Compatibility promoter 1: Glycidyl methacrylate grafted branched styrene-acrylonitrile copolymer, wherein the mass percentage of branched styrene-acrylonitrile is 97%, the mass percentage of glycidyl methacrylate is 3%, and the epoxy value is 0.48 mol / 100 g, self-made;

[0053] Compatibility promoter 2: Glycidyl methacrylate grafted branched styrene-acrylonitrile copolymer, wherein the mass percentage of branched styrene-acrylonitrile is 92%, the mass percentage of glycidyl methacrylate is 8%, and the epoxy value is 0.1 mol / 100 g;

[0054] Compatibility promoter 3: Glycidyl methacrylate grafted branched styrene-acrylonitrile copolymer, wherein the mass percentage of branched styrene-acrylonitrile is 88%, the mass percentage of glycidyl methacrylate is 12%, and the epoxy value is 0.05 mol / 100 g, self-made;

[0055] Compatibility promoter 4: Glycidyl methacrylate grafted branched styrene-acrylonitrile copolymer, wherein the mass percentage of branched styrene-acrylonitrile is 99.5%, the mass percentage of glycidyl methacrylate is 0.5%, and the epoxy value is 0.56 mol / 100 g, self-made;

[0056] Antioxidant: A mixture of a hindered phenol antioxidant and a phosphite antioxidant with a mass ratio of 1:1, commercially available;

[0057] Lubricant: Pentaerythritol stearate, commercially available.

[0058] Examples 1-13 and Comparative Examples 1-9

[0059] Examples 1-13 and Comparative Examples 1-9 of the present invention provide an SMA material, and the component contents of the SMA material are shown in Table 1-2;

[0060] Table 1

[0061]

[0062]

[0063] Table 2

[0064]

[0065]

[0066] The preparation method of the compatibilizing promoter 1 is as follows: Branched styrene-acrylonitrile copolymer and glycidyl methacrylate are mixed in a mass ratio of 98:2, and at the same time, 0.3% of dicumyl peroxide based on the total mass of the branched styrene-acrylonitrile copolymer and glycidyl methacrylate is added. After mixing the three evenly, they are added to a twin-screw extruder for melt extrusion to obtain the compatibilizing promoter 1. When extruding, the length-diameter ratio of the screw is 48:1, the extrusion temperature is 185 °C, and the screw speed is 300 rpm. The only difference in the preparation processes of the compatibilizing promoters 2-4 and the compatibilizing promoter 1 lies in the different mass ratios of the branched styrene-acrylonitrile copolymer and glycidyl methacrylate. The mass ratio of the branched styrene-acrylonitrile copolymer and glycidyl methacrylate in the compatibilizing promoter 2 is 95:5, the mass ratio of the branched styrene-acrylonitrile copolymer and glycidyl methacrylate in the compatibilizing promoter 3 is 94.4:5.6, and the mass ratio of the branched styrene-acrylonitrile copolymer and glycidyl methacrylate in the compatibilizing promoter 4 is 99.8:0.2.

[0067] The preparation method of the SMA materials in Examples 1-13 and Comparative Examples 1-9 is as follows: The dried SMA resin, toughening agent, glass microspheres, compatibilizing promoter, antioxidant, and lubricant are mixed evenly by a high-speed mixer and then added to the main feeder of a twin-screw extruder (screw diameter is 35 mm, length-diameter ratio is L / D = 48). Subsequently, the dried glass fiber is added to the twin-screw extruder through a side feeder. The temperature of each section of the main barrel (from the feeding port to the die head outlet) is controlled at 200 °C, 220 °C, 230 °C, 240 °C, 250 °C, 250 °C, and 260 °C respectively, the twin-screw speed is 500 rpm, and the extruded strip is cooled, dried, and pelletized to obtain the SMA material (if there is no relevant component, it can be not added).

[0068] Effect Example

[0069] In this effect example, the properties of the SMA materials prepared in Examples 1-13 and Comparative Examples 1-9 were tested. After drying the products of the above examples and comparative examples in a forced-air oven at 110 °C for 4 hours, they were injection-molded into standard specimens and test plates using an injection molding machine. After the injection-molded specimens were placed in an environment with a relative humidity of 50 ± 5% and a temperature of 23 ± 2 °C for at least 24 hours (the specific placement time was 36 h), performance tests were carried out, including the following tests:

[0070] 1. Flexural modulus, referring to ISO 178-2016 standard, flexural rate 2 mm / min;

[0071] 2. Impact strength, referring to ISO 179-2010 standard, no notch, pendulum energy 4 J;

[0072] 3. Dimensional shrinkage rate: Using a standard size mold of 199.85 * 50 * 2 mm, injection mold 10 samples of the above size with an injection molding machine, randomly select 5 of them to test the actual sample size, and calculate the shrinkage rate;

[0073] 4. Coefficient of linear expansion: Test on TMA according to the standard process, temperature range (-30)-100 °C, heating rate 10 °C / min, test the flow direction and the direction perpendicular to the flow respectively;

[0074] 5. Part test: Injection mold skylight parts with the above materials, use a coordinate measuring machine to measure the actual size of the parts, randomly select 100 points to test whether the part size meets the requirements. If all meet the requirements, it is OK; if one does not meet the requirements, it is NG;

[0075] The test results are shown in Table 3;

[0076] Table 3

[0077]

[0078]

[0079] It can be seen from the data in Table 3 that when the technical solution of the present invention is adopted, the obtained SMA material has excellent dimensional stability and mechanical properties; specifically, the flexural modulus of the SMA material provided by the present invention is above 7750 MPa, the impact strength is above 7.5 kJ / m 2 Above, the molding shrinkage rates in the horizontal and vertical directions are excellent, showing excellent dimensional stability. The molding shrinkage rate in the horizontal direction is between 0.24-0.33%, and the molding shrinkage rate in the vertical direction is between 0.38-0.42%. And the obtained coefficient of linear expansion is low, reflecting excellent stability. The coefficients of linear expansion in the flow direction and the direction perpendicular to the flow are respectively 17.5 * 10^-6 K -1 、39.4 * 10^-6 K -1 Below, and the obtained part sizes all meet the requirements;

[0080] It can be seen from Example 1 and Examples 5-6 that the content of maleic anhydride in the SMA resin will affect the performance of the product. When the mass percentage of maleic anhydride in the SMA resin is preferably 10-20%, the comprehensive performance of the obtained product is more excellent. Specifically, the obtained flexural modulus is above 9300 MPa, and the impact strength is above 12 kJ / m 2 Above, the linear expansion coefficients in the flow direction and the direction perpendicular to the flow direction are respectively at 15.2*10^-6 K -1 、36.3*10^-6 K -1 Below;

[0081] It can be seen from Example 1, Examples 8-10 and Comparative Example 5 that only when the chopped glass fibers of the present invention are selected, the obtained product has excellent dimensional stability and mechanical properties. When the chopped glass fibers are not used in Comparative Example 5, the obtained stability significantly decreases, and unqualified situations are found during the process of testing the dimensional requirements, and the obtained mechanical properties also show a downward trend. Compared with Example 1, the flexural modulus decreases by 22.58% and the impact strength decreases by 45.83%. Further, it can be seen from Example 1 and Examples 8-10 that when the average monofilament diameter of the chopped glass fibers is further preferably 10-13 μm, compared with when the average monofilament diameter is not within 10-13 μm, the mechanical properties of the obtained product are more excellent, manifested as the flexural modulus is above 8300 MPa and the impact strength is above 9.5 kJ / m 2 Above;

[0082] It can be seen from Example 1 and Comparative Example 1 that when no glass beads are added in the present invention, the stability of the obtained product is significantly deteriorated, and the mechanical properties of the obtained product also show an obvious downward trend. Compared with Example 1, the molding shrinkage rates in the horizontal and vertical directions increase by 48.28% and 38.46% respectively, the flexural modulus decreases by 31.18%, and the impact strength decreases by 25%. It can be seen from Example 1 and Comparative Example 2 that when the mass fraction of the added glass beads is too large, although the flexural modulus of the product will be improved, the impact strength of the product will be significantly decreased. Compared with Example 1, the decrease amplitude reaches 66.67%, and the dimensional test of the obtained product also does not meet the requirements. Further, it can be seen from Example 1, Examples 11-12 and Comparative Examples 6-7 that the average particle size of the glass beads will also affect the performance of the product. When the particle size of the glass beads is within the range of 40-50 μm given in the present invention, good dimensional stability and excellent mechanical properties of the product can be ensured;

[0083] It can be seen from Example 1 and Comparative Examples 8-9 that excellent effects can be achieved only when the mass percentages of styrene and acrylonitrile and the epoxy value in the compatibility promoter are within the ranges given in the present invention. When either the mass percentages of styrene and acrylonitrile or the epoxy value in the compatibility promoter used is not within the scope of the present invention, the mechanical properties of the obtained product show a significant downward trend, and the size of the obtained product also does not meet the requirements. Specifically, compared with Example 1, the decrease in flexural modulus is 10.43-11.83%, and the decrease in impact strength is 29.17-30%.

[0084] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An SMA material, characterized in that, the SMA material comprises the following components in parts by mass: 35 - 67 parts of SMA resin, 2 - 5 parts of toughening agent, 10 - 20 parts of glass fiber, 10 - 20 parts of glass microbeads, 1 - 6 parts of compatibilization promoter; the average length of the glass fiber is 3 - 4.5 mm; the D50 particle size of the glass microbeads is 40 - 50 μm; the compatibilization promoter is glycidyl methacrylate grafted branched styrene - acrylonitrile copolymer, in the glycidyl methacrylate grafted branched styrene - acrylonitrile copolymer, the mass percentage of branched styrene - acrylonitrile is 90 - 99%, the mass percentage of glycidyl methacrylate is 1 - 10%, and the epoxy value is 0.08 - 0.5 mol / 100 g.

2. The SMA material according to claim 1, characterized in that, in the SMA resin, the mass percentage of maleic anhydride is 6 - 25%.

3. The SMA material according to claim 1, characterized in that, the toughening agent is acrylonitrile - butadiene - styrene high rubber powder and / or ethylene - butyl acrylate - glycidyl methacrylate terpolymer.

4. The SMA material according to claim 1, characterized in that, the average monofilament diameter of the glass fiber is 10 - 15 μm.

5. The SMA material according to claim 1, characterized in that, the SMA material further comprises 0.5 - 2 parts of processing aid.

6. The SMA material according to claim 5, characterized in that, the processing aid is antioxidant and / or lubricant.

7. A method for preparing the SMA material according to any one of claims 1 - 6, characterized in that, the preparation method comprises the following steps: mixing the components except the glass fiber in the components and adding them into the main feeder of the extruder, then adding the glass fiber into the extruder through the side feeder, then melting, extruding, cooling, drying and pelletizing to obtain the SMA material.

8. The preparation method according to claim 7, characterized in that, during the extrusion process, the length - diameter ratio of the screw is (25 - 48):1, the vacuum degree is (-0.08) - (-0.1) MPa, the temperature of the feeding section is 200 - 220 °C, the temperature of the plasticizing section is 230 - 250 °C, the temperature of the subsequent homogenizing and extruding section is 240 - 260 °C, and the screw speed is 400 - 600 rpm.

9. Application of the SMA material according to any one of claims 1 - 6 in preparing automotive skeleton parts.

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