Shape memory matrix resin as well as preparation method and application thereof

Abstract

The invention provides shape memory matrix resin as well as a preparation method and application thereof. The shape memory matrix resin comprises the following components: 3-15 parts of a cosolvent; 80 to 150 parts of bisphenol A diglycidyl ether; 5 to 30 parts of triphenol monomer glycidyl ether; 5-30 parts of core-shell particles; 5 to 30 parts of a polyurethane prepolymer; 5-25 parts of amino-terminated liquid rubber; 1-20 parts of an inorganic nano filler; 0.1 to 5 parts of polydimethylsiloxane; 28 to 49 parts of a cross-linking agent; and 1-3 parts of an accelerant. According to the resin, bisphenol A diglycidyl ether is used as a main monomer, a cosolvent is used as a viscosity modifier, triphenol monomer glycidyl ether is used as an auxiliary monomer, a polyurethane prepolymer and amino-terminated liquid rubber are used as flexible modifiers, core-shell particles are used as anti-impact modifiers, and an inorganic nano filler is used as a reinforcing rheological agent. The shape memory matrix resin is formed through step-by-step ring-opening addition polymerization. The flexibility of the shape memory matrix resin is enhanced, and a micro-phase separated three-dimensional network structure is formed, so that the shape memory matrix resin is endowed with good performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of smart materials, and particularly relates to a shape memory matrix resin, a preparation method and application thereof. BACKGROUND

[0002] A prepreg is an intermediate material made by pre-impregnating reinforcing fibers (such as carbon fibers, glass fibers, etc.) in an incompletely cured resin matrix. It is usually provided in the form of a roll or a sheet and can be cured into a final high-performance composite product under the conditions of heating and pressurization. The prepreg composed of high-performance reinforcing bodies such as carbon fibers and glass fibers and a thermosetting resin matrix (such as epoxy resin, phenolic resin, bismaleimide, polyimide) has been widely used in the fields of aerospace, sports equipment, industrial equipment, etc. due to its high specific strength, high specific modulus and excellent design freedom. However, the traditional prepreg forms a highly cross-linked three-dimensional network structure after curing, which is rigid and brittle. This leads to the fact that once the composite product is cured and formed, its shape and size are permanently fixed and cannot be substantially deformed or adjusted. This inherent static characteristic greatly limits the application of composites in the fields of dynamic deformation, self-adaptive structure or deployable structure, such as deformable wing skin, deployable space structure and highly conformable smart wearable devices.

[0003] Aramid fibers are known for their excellent mechanical properties and excellent impact resistance and energy absorption capacity. The introduction of aramid fibers (such as Kevlar) into composites can impart certain flexibility and deformability to the composites. Directly using aramid in the traditional prepreg system faces the following technical obstacles that are difficult to overcome, such as the smooth surface of aramid fibers, chemical inertness, and highly crystalline core-sheath structure. Its surface energy is low, and it lacks active sites to form strong chemical bonds or physical engagement with the resin matrix (such as epoxy resin). Aramid fibers themselves have low compressive strength, and under compression load, the fibers are prone to micro buckling and failure; this is different from the brittle fracture mechanism of carbon fibers. When stressed, the load cannot be effectively transferred from the resin to the fibers, leading to easy debonding and damage at the interface, not only failing to take advantage of the toughness of aramid, but also becoming a mechanical defect in the composite. The structure and function are single, and even if aramid prepreg is successfully prepared, the product usually only has passive and simple elastic deformation capacity (such as stretch and rebound), and lacks active and programmable shape change capability. It cannot realize the intelligent behavior of automatically converting from one preset shape to another preset shape under external stimuli (such as heat and electricity).

[0004] Shape memory polymers (SMPs) are a class of smart materials that can recover from a temporary shape to their original permanent shape upon external stimuli (e.g. heat, light, electricity, magnetism). Epoxy resins can be endowed with shape memory properties by molecular design. However, pure shape memory epoxy resin products usually have low modulus and poor strength, and are difficult to be used as load-bearing structural parts. Although they can be reinforced by adding rigid fibers (such as carbon fibers, glass fibers), it is inevitable to significantly sacrifice their recoverable strain, making them degenerate from a smart material to a common rigid composite, losing the ability of large deformation and shape change. SUMMARY

[0005] The purpose of the present application is to provide a shape memory matrix resin, its preparation method and application, in order to solve at least part of the above problems.

[0006] The first aspect of the present application provides a shape memory matrix resin, comprising, in terms of mass fraction: 3-15 parts of a cosolvent; 80-150 parts of bisphenol A diglycidyl ether; 5-30 parts of a triphenol monomer glycidyl ether; 5-30 parts of a core-shell particle; 5-30 parts of a polyurethane prepolymer; 5-25 parts of an amino-terminated liquid rubber; 1-20 parts of an inorganic nano-filler; 0.1-5 parts of a polydimethylsiloxane; 28-49 parts of a crosslinking agent; and 1-3 parts of an accelerator.

[0007] Optionally, the cosolvent is one or more of a combination of ethylene glycol monobutyl ether, ethylene glycol propyl ether, ethylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol butyl ether, propylene glycol diacetate, N,N-dimethylformamide and N,N-dimethylacetamide.

[0008] Optionally, the triphenol monomer glycidyl ether is a combination of tris(4-hydroxyphenyl)methane triglycidyl ether, tris(4-hydroxyphenyl)ethane and tris(4-hydroxyphenyl)propane.

[0009] Optionally, the core-shell particle comprises a silicone core material and a polymethacrylate shell.

[0010] Optionally, the inorganic nano-filler is one or more of a combination of nano-silicon dioxide, nano-titanium dioxide and nano-aluminum oxide.

[0011] Optionally, the crosslinking agent is one or more of a combination of aliphatic amine, aromatic amine, phenolic amine, polyamide or cashew phenol modified amine.

[0012] Optionally, the accelerator is a catalyst for the epoxy system.

[0013] The second aspect of the present application provides a preparation method of a shape memory matrix resin, comprising:

[0014] The cosolvent, bisphenol A diglycidyl ether and triphenol monomer glycidyl ether are heated, mixed and kept, to obtain a first premix liquid;

[0015] The core-shell particles are added into the first premix liquid and mixed, to obtain a second premix liquid;

[0016] The polyurethane prepolymer and the amino-terminated liquid rubber are heated, mixed and kept, to obtain a third premix liquid;

[0017] After the second premix liquid and the third premix liquid are heated, mixed and kept, the inorganic nano-filler and the polydimethylsiloxane are added and mixed, to obtain a fourth premix liquid;

[0018] The crosslinking agent and the accelerator are added into the fourth premix liquid cooled to normal temperature, and stirred and vacuumed to discharge, to obtain a shape memory matrix resin.

[0019] The third aspect of the present application provides a preparation method of a fiber prepreg based on a shape memory matrix resin, comprising:

[0020] The shape memory matrix resin is placed into a dipping tank;

[0021] The aramid fiber material is unwound through the dipping tank, and cold pressing composite impregnation is performed in a normal temperature environment of 0.3-0.8 MPa, to obtain an initial prepreg;

[0022] After the initial prepreg is cooled to-30℃ by a cooling roller, release paper is coated on one side or both sides of the prepreg and wound, to obtain a fiber prepreg based on a shape memory matrix resin.

[0023] The fourth aspect of the present application provides an application of a fiber prepreg based on a shape memory matrix resin, which is used as a raw material for manufacturing a flexible-rigid integrated structure.

[0024] The present application has the following beneficial effects:

[0025] The shape memory matrix resin of the present solution uses bisphenol A diglycidyl ether as the main monomer, uses a cosolvent as a viscosity regulator, uses a triphenol monomer glycidyl ether type as an auxiliary monomer, uses a polyurethane prepolymer and an amino-terminated liquid rubber as a flexible modifier, uses a core-shell particle as an impact modifier, and uses an inorganic nano-filler as a reinforcing agent. The shape memory matrix resin is formed by step-by-step ring-opening addition polymerization. The resin can undergo the following crosslinking reactions: (1) the isocyanate group of the polyurethane prepolymer reacts with the epoxy group of the glycidyl ether to form a urethane bond; (2) the primary amino group at both ends of the flexible chain of the amino-terminated liquid rubber reacts with the epoxy group to form a secondary amine and a secondary hydroxyl group; and (3) the amino group of the amine curing agent reacts with the epoxy group to form a carbon-nitrogen bond and a hydroxyl group. Due to the above crosslinking reactions, flexible chain segments are introduced into the rigid network, and an ideal multi-phase structure is formed through physical phase separation (blending of core-shell particles and inorganic nano-filler), which synergistically enhances the flexibility of the shape memory matrix resin on the molecular and microscale, and forms a micro-phase-separated three-dimensional network structure, thereby providing good performance.

[0026] Then, the rheological properties of the shape memory matrix resin are utilized to coat the aramid fibers at room temperature, and the aramid fiber prepreg with the advantages of both shape memory materials and aramid fibers is obtained through the conventional winding and storage process. The prepreg can be cured to form a rigid-flexible-intelligent integrated composite material, which can realize intelligent circulation from a rigid bearing state to a large elastic deformation state and then to the original state under a specific stimulus. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a flowchart of the preparation method of the shape memory matrix resin.

[0028] Figure 2 It is a flowchart of the preparation method of the fiber prepreg based on the shape memory matrix resin.

[0029] Figure 3 It is a structure diagram of the real comparison experiment between the commercial carbon fiber prepreg and the shape memory aramid fiber prepreg of the present solution. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present solution clearer and more apparent, the present solution is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present solution and do not limit the present solution.

[0031] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application; the terms "first", "second", "third" are only for description purposes, and cannot be understood as indicating or implying relative importance; in addition, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, or the communication between two components. For those skilled in the art, the specific meaning of the terms in the present application can be understood according to the specific circumstances.

[0032] The existing prepreg and its manufacturing method has inherent defects such as single deformation mode, limited manufacturing process, poor material performance and insufficient intelligent level of operation. The purpose of the present application is to overcome the above-mentioned defects, and to provide a shape memory matrix resin, its preparation method and application, aiming to solve the following technical problems:

[0033] Solve the bottleneck problem of manufacturing process in material design: after traditional composite material curing, the shape is fixed and cannot meet the application scene of bending and torsional deformation; and brittle fracture occurs when impacted, poor tear resistance; realize the design paradigm change from rigid composite material to flexible / deformable composite material.

[0034] The embodiment provides a shape memory matrix resin, comprising: 3-15 parts of a cosolvent; 80-150 parts of bisphenol A diglycidyl ether; 5-30 parts of a triphenol monomer glycidyl ether; 5-30 parts of core-shell particles; 5-30 parts of a polyurethane prepolymer; 5-25 parts of an amino-terminated liquid rubber; 1-20 parts of an inorganic nano-filler; 0.1-5 parts of a polydimethylsiloxane; 28-49 parts of a crosslinking agent; and 1-3 parts of an accelerator.

[0035] Among them, the bisphenol A diglycidyl ether is a bifunctional monomer, the triphenol monomer glycidyl ether is a trifunctional monomer, in addition to the step-by-step addition polymerization reaction with the crosslinking agent, it also reacts with the polyurethane prepolymer and the amino-terminated liquid rubber to introduce flexible chain segments into the rigid structure.

[0036] The core-shell particle is an impact modifier with silicone rubber as the core and acrylate as the shell. The shell is made of rigid material and the core is made of elastomer such as rubber, which has a special core-shell structure. The market can be purchased regularly, and the representative manufacturers are Japan Zhongyuan MX-962, Dow Chemical TMS2672, and South Korea Jinhu HR-181.

[0037] The polyurethane prepolymer is a self-made HDI type polyurethane prepolymer containing a certain amount of NCO groups, which can react with bisphenol A diglycidyl ether to improve the flexibility and deformation of the cross-linked material.

[0038] The preparation process of the polyurethane prepolymer is as follows: 80g of polytetrahydrofuran ether diol is weighed and poured into a three-necked flask, then it is placed in an 80℃ oil bath with stirring at a speed of 300r / min and heating, and argon is introduced for protection; After stirring evenly, 20.024g of hexamethylene diisocyanate is added, and the reaction is kept for 45min, and the filtrate is obtained to obtain a self-made HDI type polyurethane prepolymer.

[0039] The amino-terminated liquid rubber is a low-molecular-weight liquid polymer containing amino groups, which can chemically react with the epoxy groups of glycidyl ether and be connected to the polymer network in the form of chemical bonds. The amino-terminated liquid rubber is a commercially available raw material, which is sold by Tianyuan Aviation Material Technology Co., Ltd. and Shanghai Citaolong Industrial Co., Ltd.

[0040] The inorganic nano-filler includes but is not limited to nano-silicon dioxide, nano-titanium dioxide, nano-alumina, and nano-particles. The huge specific surface area of the nano-particles can improve the heat resistance and wear resistance of the base resin, and play a reinforcing role.

[0041] The polydimethylsiloxane includes but is not limited to polyether-modified polydimethylsiloxane and ordinary polydimethylsiloxane, which can be added in the middle or after use, and has the functions of wetting and defoaming.

[0042] The cross-linking agent includes but is not limited to aliphatic amines (such as ethylenediamine and diethylenetriamine), polyamides (such as polyamide 650 and polyamide 651), aromatic amines (such as m-xylylenediamine and DDS), phenolic amines (such as TZ-46 and T-31), and cashew phenol-modified amines (such as WSCM-2372 and NX-2041). The cross-linking agent can react with bisphenol A diglycidyl ether to form a three-dimensional network cross-linking structure.

[0043] The accelerator is a kind of amine accelerator, including but not limited to K54, DMP-30, BDMA, DMP-10, etc. The accelerator is a catalyst for the epoxy system, which can shorten the gel time of the epoxy system, and a single or two mixed ones can be used.

[0044] The respective roles of bisphenol A diglycidyl ether, triphenol monomer glycidyl ether, polyurethane prepolymer, amino-terminated liquid rubber, inorganic nano-filler, core-shell particle, and polydimethylsiloxane are as follows: bisphenol A diglycidyl ether imparts rigidity to the resin; triphenol monomer glycidyl ether improves heat resistance and modulus; polyurethane prepolymer and amino-terminated liquid rubber introduce flexible segments into the rigid structure; inorganic nano-filler and core-shell particle improve the toughness and impact resistance of the resin; and polydimethylsiloxane increases the wettability of the matrix resin on aramid fibers and eliminates microbubbles generated during coating.

[0045] Referring to Figure 1 The embodiment discloses a preparation method of a shape memory matrix resin, which comprises the following steps:

[0046] S11, heating, mixing and preserving a cosolvent, bisphenol A diglycidyl ether and triphenol monomer glycidyl ether to obtain a first premix;

[0047] S12, adding a core-shell particle to the first premix to obtain a second premix;

[0048] S13, heating, mixing and preserving a polyurethane prepolymer and an amino-terminated liquid rubber to obtain a third premix;

[0049] S14, after heating, mixing and preserving the second premix and the third premix, adding an inorganic nano-filler and polydimethylsiloxane to obtain a fourth premix;

[0050] S15, adding a crosslinking agent and an accelerator to the fourth premix cooled to room temperature, stirring, vacuumizing and discharging to obtain a shape memory matrix resin.

[0051] Referring to Figures 2-3 The embodiment further discloses a preparation method of a fiber prepreg based on the shape memory matrix resin, which comprises the following steps:

[0052] S21, placing the shape memory matrix resin described above into a glue tank;

[0053] S22, unwinding aramid fiber material through the glue tank and performing cold pressure composite impregnation in a room temperature environment at 0.3-0.8 MPa to obtain an initial prepreg;

[0054] It should be explained that the cold pressure composite impregnation does not mean resin impregnation of aramid fiber at low temperature, but is lower in temperature compared with the traditional impregnation method, and can be completed at room temperature without heating and melting the resin, which is more energy-saving and environmentally friendly.

[0055] S23, after the initial prepreg is cooled to -30 DEG C by a cooling roller, a release paper is coated on one side or both sides of the prepreg to obtain a fiber prepreg product based on a shape memory matrix resin.

[0056] The aramid fiber includes, but is not limited to, Kevlar aramid fiber, Twaron aramid fiber, Technora aramid fiber, DuPont aramid fiber, and TAPRON aramid fiber.

[0057] The prepreg prepared by the above preparation method has the following beneficial effects:

[0058] (1) The prepreg prepared by the method can be impregnated at room temperature without heating and melting, thereby reducing the energy consumption of equipment; and the curing method is flexible, and normal temperature curing or heating curing can be selected;

[0059] (2) The prepreg prepared by the method can realize high-curvature or deep-stretch forming, has good elongation, and the aramid fiber layer in the prepreg can withstand greater tensile deformation during mold pressing or vacuum bag pressing forming, thereby better fitting the complex mold and reducing forming defects;

[0060] (3) The prepreg prepared by the method can give the composite material good energy absorption and damping properties; the aramid fiber rich in memory resin has good impact resistance as a high polymer elastomer at a regulated temperature, and the internal friction of the molecular chain segment can consume a large amount of energy when repeatedly stretched and recovered, thereby achieving damping properties;

[0061] (4) The prepreg prepared by the method can significantly improve the toughness, impact resistance and damage tolerance of the composite material, and effectively prevent brittle failure.

[0062] The prepreg prepared by the method can realize the structure variability and shape self-adaptation of the composite material, and the shape epoxy resin matrix contained in the prepreg can enable the composite material to shape a complex variable structure.

[0063] Example 1

[0064] The embodiment provides a shape memory matrix resin, which comprises the following components in parts by mass: 3 parts of propylene glycol methyl ether, 90 parts of bisphenol A diglycidyl ether, 7 parts of triphenylolmethane triglycidyl ether, 5 parts of core-shell particles, 7 parts of polyurethane prepolymer, 8 parts of amino-terminated liquid rubber, 4 parts of inorganic nano-filler, 1.2 parts of polydimethylsiloxane, 38 parts of crosslinking agent, and 1 part of accelerator.

[0065] The co-solvent is propylene glycol methyl ether, which has good solubility and can effectively improve the fluidity and processability of the resin system. In a preferred embodiment, the co-solvent can also be selected from one or more combinations of ethylene glycol monobutyl ether, ethylene glycol propyl ether, ethylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol ethyl ether, propylene glycol butyl ether, propylene glycol diacetate, N,N dimethylformamide and N,N dimethylacetamide. The amount of co-solvent used is in the range of 3-15 parts, preferably 3-8 parts, and more preferably 3-5 parts.

[0066] Bisphenol A diglycidyl ether is used as the main epoxy resin matrix, providing the basic crosslinking network structure. Its amount is 80-150 parts, and 90 parts are used in this embodiment, which can ensure that the resin has good mechanical properties and shape memory effect.

[0067] The triphenol monomer glycidyl ether uses triphenylmethane triglycidyl ether, which is a combination of tris(4-hydroxyphenyl)methane triglycidyl ether, tris(4-hydroxyphenyl)ethane and tris(4-hydroxyphenyl)propane. This component can increase the crosslinking density and improve the glass transition temperature of the resin, thereby improving the shape memory performance. Its amount is 5-30 parts, and 7 parts are used in this embodiment.

[0068] The core-shell particles include a silicone core material and a polymethyl acrylate shell. The silicone core material provides flexibility, and the polymethyl acrylate shell ensures good compatibility with the matrix resin. The addition of core-shell particles can effectively improve the toughness and impact resistance of the resin, preventing cracks during shape memory. Its amount is in the range of 5-30 parts, and 5 parts are used in this embodiment.

[0069] The addition of polyurethane prepolymer can form an elastic network structure during resin curing, providing the necessary elastic recovery force for shape memory. Its amount is 5-30 parts, and 7 parts are used in this embodiment, which synergistically acts with the amino-terminated liquid rubber to further improve the shape memory performance of the resin.

[0070] The amount of amino-terminated liquid rubber used is 5-25 parts, and 8 parts are used in this embodiment. This component can react with epoxy groups to form flexible segments in the cured network, providing the necessary molecular chain movement space for shape memory.

[0071] The inorganic nano-filler is selected from one or more combinations of nano-silicon dioxide, nano-titanium dioxide and nano-aluminum oxide, and 4 parts are used in this embodiment. The addition of nano-filler can significantly improve the modulus and thermal stability of the resin, while improving the accuracy and stability of shape memory. Its amount is in the range of 1-20 parts, preferably 2-8 parts.

[0072] The amount of polydimethylsiloxane is 0.1-5 parts, and 1.2 parts is used in this embodiment. This component serves as an internal lubricant, which can improve the fluidity and demolding performance of the resin, and at the same time, to a certain extent, improve the flexibility of the resin.

[0073] The crosslinking agent is selected from aliphatic amine, aromatic amine, polyamide, phenolic amine or cashew phenol modified amine, and 38 parts is used in this embodiment. The crosslinking agent reacts with the epoxy group to form a three-dimensional crosslinking network, which is a key component to realize the shape memory function. The amount is 30-60 parts, which needs to be accurately calculated according to the epoxy equivalent to ensure complete curing.

[0074] The accelerator uses the catalyst of the epoxy system, and the amount is 1-3 parts, and 1 part is used in this embodiment. The accelerator can accelerate the curing reaction, shorten the curing time, and improve the curing efficiency.

[0075] The shape memory matrix resin has excellent shape memory performance. When heated to above the glass transition temperature, the material becomes soft and can be plastically deformed, and after cooling, it can maintain the deformed shape, and when heated again, it can return to the original shape. The glass transition temperature of the cured resin is moderate, the shape memory recovery rate is high, the mechanical properties are excellent, and it is suitable for preparing various shape memory composites and structural parts.

[0076] The preparation process of the shape memory matrix resin is as follows: first, add propylene glycol methyl ether, bisphenol A diglycidyl ether, and triphenyl monomer glycidyl ether into a reaction bottle, and heat to 75°C for 0.5 hours under stirring, and keep for 1 hour to obtain a first premix liquid. Then add the core-shell particles to the first premix liquid, and stir at medium speed to disperse them uniformly in the first premix liquid, and stir for 0.5 hours to obtain a second premix liquid. Add the polyurethane prepolymer and amino-terminated liquid rubber to the reaction bottle, and heat to 75°C for 0.5 hours under stirring, and keep for 1 hour to obtain a third premix liquid. Add the second premix liquid and the third premix liquid to the reaction bottle, and heat to 80°C for 0.5 hours under stirring, and keep for 1 hour for reaction, and then reduce to 60°C, and add inorganic nano-filler and polydimethylsiloxane, and stir at high speed until there are no obvious particles, to obtain a fourth premix liquid. Add the measured crosslinking agent and accelerator to the fourth premix liquid after it is reduced to room temperature, and stir and vacuum to discharge to obtain the shape memory matrix resin.

[0077] The shape memory matrix resin has excellent shape memory performance. When heated to above the glass transition temperature, the material becomes soft and can be plastically deformed, and after cooling, it can maintain the deformed shape, and when heated again, it can return to the original shape. The glass transition temperature of the cured resin is moderate, the shape memory recovery rate is high, the mechanical properties are excellent, and it is suitable for preparing various shape memory composites and structural parts.

[0078] Preparation of the prepreg:

[0079] The aramid fiber is spread by using normal temperature impregnation method, and is impregnated in the impregnation groove containing the resin glue liquid under the pressure of 0.5 MPa. The impregnated prepreg is cooled to-30℃ by a cooling roller, and is covered with a release paper on the other side, and is wound, so that the shape memory aramid prepreg is obtained.

[0080] Example two

[0081] The embodiment provides a shape memory matrix resin which comprises the following components and contents in mass fraction: 15 parts of N,N-dimethylacetamide, 150 parts of bisphenol A diglycidyl ether, 12 parts of triphenol methane triglycidyl ether, 20 parts of core-shell particles, 5 parts of polyurethane prepolymer, 25 parts of amino-terminated liquid rubber, 1 part of inorganic nano-filler, 5 parts of polydimethylsiloxane, 49 parts of crosslinking agent, and 2 parts of accelerator.

[0082] Step one: preparing a first premix liquid

[0083] The N,N-dimethylacetamide, bisphenol A diglycidyl ether and triphenol methane triglycidyl ether are added into a reaction bottle, and are heated to 80℃ for 1.0 hour under stirring, and are kept for 1.5 hours, so that the first premix liquid is obtained. The N,N-dimethylacetamide as a cosolvent can effectively improve the fluidity and compatibility of the system, the bisphenol A diglycidyl ether as a main epoxy resin matrix provides basic mechanical properties, and the addition of the triphenol methane triglycidyl ether can increase the crosslinking density and improve the thermal stability of the material.

[0084] Step two: preparing a second premix liquid

[0085] The core-shell particles are added into the first premix liquid, and are uniformly dispersed in the first premix liquid under medium-speed stirring, and are stirred for 0.8 hours, so that the second premix liquid is obtained. The addition of the core-shell particles can significantly improve the toughness and impact resistance of the material, and does not obviously reduce the rigidity of the material.

[0086] Step three: preparing a third premix liquid

[0087] The polyurethane prepolymer and the amino-terminated liquid rubber are added into another reaction bottle, and are heated to 82℃ for 1.2 hours under stirring, and are kept for 1.5 hours, so that the third premix liquid is obtained. The polyurethane prepolymer can provide excellent elastic recovery performance, and the introduction of the amino-terminated liquid rubber further enhances the flexibility and shape memory effect of the material.

[0088] Step four: preparing a fourth premix liquid

[0089] The second premix and the third premix are added to the reaction bottle, and heated to 82°C for 1.5 hours under stirring, and then cooled to 60°C. Then, the inorganic nano-filler and the polydimethylsiloxane are added, and stirred at high speed until no obvious particles are observed, to obtain a fourth premix. The inorganic nano-filler can improve the mechanical strength and thermal stability of the material, and the addition of the polydimethylsiloxane improves the processing performance and surface properties of the material.

[0090] Step five: preparation of the shape memory matrix resin

[0091] The fourth premix cooled to room temperature is added with the measured crosslinking agent and the accelerator, and then stirred and vacuumed to discharge the shape memory matrix resin. The addition of the crosslinking agent enables the components to form a stable three-dimensional network structure, and the accelerator accelerates the crosslinking reaction to ensure that the material has good shape memory performance.

[0092] Preparation of the prepreg: the aramid fibers are spread by the cold impregnation method, and then impregnated in the impregnation tank containing the resin glue solution under a pressure of 0.5 MPa. The impregnated prepreg is cooled to -30°C by a cooling roller, and then covered with a release paper on the other side, and then wound up to obtain the shape memory aramid prepreg.

[0093] Example three

[0094] The shape memory matrix resin provided in this example comprises the following components and contents in mass fraction: 5 parts of ethylene glycol monobutyl ether, 88 parts of bisphenol A diglycidyl ether, 30 parts of triphenol monomer glycidyl ether, 30 parts of core-shell particles, 30 parts of polyurethane prepolymer, 5 parts of amino-terminated liquid rubber, 20 parts of inorganic nano-filler, 0.1 part of polydimethylsiloxane, 28 parts of crosslinking agent, and 3 parts of accelerator.

[0095] The preparation method of the shape memory matrix resin in this scheme comprises the following steps: first, ethylene glycol monobutyl ether, bisphenol A diglycidyl ether, and triphenol monomer glycidyl ether are added to a reaction bottle, and heated to 90°C for 2 hours under stirring, to obtain a first premix; then, the core-shell particles are added to the first premix, and stirred at medium speed to uniformly disperse in the first premix, to obtain a second premix; polyurethane prepolymer and amino-terminated liquid rubber are added to the reaction bottle, and heated to 90°C for 2 hours under stirring, to obtain a third premix; the second premix and the third premix are added to the reaction bottle, and heated to 85°C for 2 hours under stirring, and then cooled to 60°C. Then, the inorganic nano-filler and the polydimethylsiloxane are added, and stirred at high speed until no obvious particles are observed, to obtain a fourth premix. The fourth premix cooled to room temperature is added with the measured crosslinking agent and the accelerator, and then stirred and vacuumed to discharge the shape memory matrix resin.

[0096] Preparation of prepreg: the aramid fiber is spread by normal temperature impregnation method, and cold composite impregnation is carried out in the impregnation tank containing the resin glue solution above under the pressure of 0.5 MPa. The impregnated prepreg is cooled to-30℃ by cooling roller, and the other side is covered with release paper, and then is wound, to obtain the shape memory aramid prepreg.

[0097] Comparative example 1

[0098] In the embodiment, the shape memory matrix resin includes N,N-dimethylacetamide 3 parts, bisphenol A diglycidyl ether 97 parts, inorganic nano filler 8 parts, polydimethylsiloxane 1.2 parts, crosslinking agent 31 parts, and accelerator 1.1 part by mass fraction.

[0099] Preparation method of shape memory matrix resin: first, N,N-dimethylacetamide and bisphenol A diglycidyl ether are added to a reaction bottle, and the temperature is raised to 75-90℃ for 0.5-2.0 hours under stirring, and then is kept for 1-2 hours to obtain a first premixed liquid; after being reduced to 60℃, the inorganic nano filler and polydimethylsiloxane are added, and high-speed stirring is carried out until no obvious particles are observed, to obtain a second premixed liquid. The crosslinking agent and accelerator are added to the second premixed liquid after being reduced to normal temperature, and the shape memory matrix resin is obtained by stirring and vacuumizing.

[0100] Preparation of prepreg: the aramid fiber is spread by normal temperature impregnation method, and cold composite impregnation is carried out in the impregnation tank containing the resin glue solution above under the pressure of 0.5 MPa. The impregnated prepreg is cooled to-30℃ by cooling roller, and the other side is covered with release paper, and then is wound, to obtain the shape memory aramid prepreg.

[0101] The shape memory matrix of the above examples and comparative examples is made into pure resin material, which is baked at 80℃ for 2 hours and then baked at 120℃ for 2 hours to solidify, and then resin performance test is carried out, and the results are shown in Table 1 as follows:

[0102] Table 1

[0103] Item Example 1 Example 2 Example 3 Comparative Example Tg / °C 98.7 96.3 100.6 118.9 Thermal Weight Loss Tl / °C 423.3 409.5 417.6 416.6 Elastic Modulus / MPa 2450 2612 2563 2900 Tensile Strength / MPa 66.2 62.3 64.6 74.2 Shape Recovery / % 98.5 99.1 98.7 56.3

[0104] The results of the examples and comparative examples show that the matrix resin of the memory material aramid fiber prepreg is modified, which can obviously reduce the elastic modulus and glass transition temperature, and obviously improve the flexibility and impact resistance of the system, and especially has excellent performance in shape memory, thereby providing high-value matrix resin support for the variability of aramid prepreg.

[0105] The shape memory prepreg of the above examples is baked at 80℃ for 2 hours and then baked at 120℃ for 2 hours to solidify, and then is compared with commercialized carbon fiber prepreg, and the results are shown in Table 2 as follows:

[0106] Table 2

[0107] Item Commercial Carbon Fiber Prepreg Example 1 Prepreg Elastic Modulus / GPa 156 103 Tensile Strength / MPa 2365 502 Elongation at Break / % 1.65 20.3 Shape Recovery / % 5.32 98.3

[0108] The results of the commercial carbon fiber prepreg and the prepreg of Example 1 show that the flexibility and shape memory function of the aramid fiber prepreg of the present application are obviously superior to the commercially available carbon fiber prepreg, and the design paradigm of the aramid prepreg rigid composite to flexible / deformable composite can be realized. Further see Figure 3 As can be seen, the left is a commercial carbon fiber prepreg, and the right is a shape memory aramid prepreg. After heating to 100°C, the shape memory aramid prepreg of the present application is elastic and can be deformed, and after cooling, it is shaped into an S shape. After heating to 100°C again, it can be deformed to restore to the initial shape. While the commercial carbon fiber cannot realize the deformation process.

[0109] Example Four

[0110] In a specific application example, the shape memory aramid prepreg prepared in Example 1 is used as a raw material for manufacturing flexible-rigid integrated structural parts.

[0111] The process for manufacturing flexible-rigid integrated structural parts is as follows: first, the shape memory aramid prepreg is cut and laid according to the design requirements, and single or double layers are laid in the area where flexibility is required, and multiple layers are laid in the area where rigidity is required. Then the laid prepreg is placed in a forming mold and hot pressed at a temperature of 80-120°C, with a pressure of 1.0-2.0 MPa, and cured for 1-3 hours to fully crosslink the matrix resin.

[0112] The cured structural part exhibits rigid characteristics at room temperature and can withstand certain mechanical loads. When the ambient temperature rises above the glass transition temperature of the shape memory matrix resin, the matrix material containing polyurethane prepolymer and amino-terminated liquid rubber softens, and the structural part changes to a flexible state and can be deformed, such as bending and folding. When the temperature decreases below the glass transition temperature, the structural part reverts to a rigid state and maintains the deformed shape.

[0113] This flexible-rigid integrated structural part can be made into a flexible joint part in wearable exoskeletons or protective gear; a driving layer or a structural layer of a soft robot; a skin of a deformable wing; a midsole or a torsion-resistant sheet in high-performance sports shoes that requires high energy rebound and shape recovery, etc.

[0114] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, several modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A shape memory matrix resin, characterized in that, Calculated by weight parts, including: 3-15 parts co-solvent; 80-150 parts of bisphenol A diglycidyl ether; 5-30 parts of triphenol monomer glycidyl ether; 5-30 portions of core-shell particles; 5-30 parts polyurethane prepolymer; 5-25 parts amino-terminated liquid rubber; 1-20 parts of inorganic nanofiller; 0.1-5 parts polydimethylsiloxane; 28-49 parts crosslinking agent; 1-3 parts accelerator.

2. The shape memory matrix resin according to claim 1, characterized in that, The co-solvent is one or more combinations of ethylene glycol monobutyl ether, ethylene glycol propyl ether, ethylene glycol monomethyl ether, diethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol butyl ether, propylene glycol diacetate, N,N-dimethylformamide, and N,N-dimethylacetamide.

3. The shape memory matrix resin according to claim 1, characterized in that, The triphenol monomer glycidyl ether is a composition of tris(4-hydroxyphenyl)methane triglycidyl ether, tris(4-hydroxyphenyl)ethane, and tris(4-hydroxyphenyl)propane.

4. The shape memory matrix resin according to claim 1, characterized in that, The core-shell particles comprise an organosilicon core and a polymethyl methacrylate shell.

5. The shape memory matrix resin according to claim 1, characterized in that, The inorganic nanofiller is one or more combinations of nano-silica, nano-titanium dioxide, and nano-alumina.

6. The shape memory matrix resin according to claim 1, characterized in that, The crosslinking agent is one or more combinations of aliphatic amines, aromatic amines, phenolic amines, polyamides, or cashew phenol-modified amines.

7. The shape memory matrix resin according to claim 1, characterized in that, The accelerator is a catalyst for an epoxy system.

8. A method for preparing a shape memory matrix resin, characterized in that, include: 3-15 parts of cosolvent, 80-150 parts of bisphenol A diglycidyl ether and 5-30 parts of triphenol monomer glycidyl ether are heated and mixed and kept at a certain temperature to obtain the first premixed solution. Add 5-30 parts of core-shell particles to the first premix and mix to obtain the second premix; 5-30 parts of polyurethane prepolymer and 5-25 parts of amino-terminated liquid rubber are heated and mixed and kept at a certain temperature to obtain a third premixed liquid. After heating and mixing the second premixed liquid with the third premixed liquid and keeping it at a certain temperature, 1-20 parts of inorganic nanofiller and 0.1-5 parts of polydimethylsiloxane are added and mixed to obtain the fourth premixed liquid; Add 28-49 parts of crosslinking agent and 1-3 parts of accelerator to the fourth premixed liquid that has been cooled to room temperature, stir, vacuum pump, and discharge to obtain shape memory matrix resin.

9. A method for preparing a fiber prepreg based on a shape memory matrix resin, characterized in that, include: The shape memory matrix resin as described in any one of claims 1-7 is placed into an impregnation tank; Aramid fiber material is unwound and passed through the impregnation tank, and then cold-pressed and composite impregnated in a room temperature environment of 0.3-0.8 MPa to obtain the initial prepreg. After the initial prepreg is cooled to -30°C by a cooling roller, release paper is applied to one or both sides of the prepreg and it is then wound up to obtain a finished fiber prepreg based on shape memory matrix resin.

10. An application of a fiber prepreg based on shape memory matrix resin, characterized in that, Used as a raw material for manufacturing flexible-rigid integrated structural components.

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