Room temperature shape memory piezoelectric polymer composite bridge joint filling material, preparation method and application thereof

Abstract

The application belongs to the technical field of bridge joint filling materials, and particularly relates to a room-temperature shape memory piezoelectric polymer composite bridge joint filling material and a preparation method and application thereof. The application obtains an epoxy resin precursor with reversible dynamic covalent bonds, i.e., disulfide bonds, and a thermoplastic polyurethane prepolymer, respectively, and then mixes the epoxy resin precursor with the thermoplastic polyurethane prepolymer to obtain a polyurethane-epoxy resin with an interpenetrating network structure. The application also prepares a piezoelectric ceramic material with piezoelectric properties. After mixing the piezoelectric ceramic material, the polyurethane-epoxy resin and a conductive agent, the application pours and cures to obtain a room-temperature shape memory piezoelectric polymer composite bridge joint filling material. The room-temperature shape memory piezoelectric polymer composite bridge joint filling material obtained by the application has room-temperature shape memory characteristics, which promotes shape memory recovery thereof at room temperature.

Description

Technical Field

[0001] The present invention belongs to the technical field of bridge filling materials, and in particular relates to a room temperature shape memory piezoelectric polymer composite bridge filling material, a preparation method and an application thereof. Background Art

[0002] Bridge expansion joints, a crucial component of bridge structures, are located at the bridge end joints. Their primary function is to regulate the displacement and deformation between the superstructures caused by temperature changes, vehicle loads, and bridge construction materials. Their quality directly impacts the overall performance and service life of the bridge. In recent years, with the continuous improvement of economic levels and the increasing complexity of traffic flows, bridges have gradually grown in length, with the construction of a large number of high-grade highways and extra-large highway bridges. This has placed higher demands on the stability of bridge expansion joints. Currently, most bridge expansion joint filling materials suffer from poor compatibility with bridge structures and poor displacement adaptability, resulting in low bridge stability and safety. Therefore, developing bridge expansion joint filling materials with excellent durability and large displacement recovery to address the problems of insufficient adaptive bridge deformation capacity and the mismatch between expansion and contraction and bridge deformation has become a hot topic in the field of bridge expansion joint research.

[0003] The shape memory effect occurs when a material is given a certain shape (initial state) under certain conditions. When external conditions change, the material can change shape accordingly and fix it (deformation). If the external environment changes again in a specific manner and pattern, it can reversibly return to its initial state, thus completing the cycle of "memorizing the initial state - fixing the deformed state - restoring the initial state." Clearly, materials with shape memory effects can flexibly switch between temporary shapes and memorized states as the external environment changes. Imbuing bridge expansion joint materials with a certain shape memory effect can effectively address the problems of mismatch between bridge expansion joint filling materials and bridge deformation, as well as poor deformation and displacement adaptation.

[0004] The prior art discloses polymer bridge filling materials which, despite having excellent mechanical properties, lack the property of self-adapting to bridge deformation. Summary of the Invention

[0005] In view of the above-mentioned deficiencies in the prior art, the present invention aims to provide a room temperature shape memory piezoelectric polymer composite bridge filling material and its preparation method and application. The present invention first separately prepares an epoxy resin precursor containing a reversible dynamic covalent disulfide bond and a thermoplastic polyurethane prepolymer, then mixes the epoxy resin precursor and the thermoplastic polyurethane prepolymer so that the molecular chains of the two penetrate each other to obtain a polyurethane-epoxy resin with an interpenetrating network structure; then prepares a chemical formula (Ba 0.85-2x Li x Al x Ca 0.15)(Zr 0.1 Ti 0.9 )O3 piezoelectric ceramic material with piezoelectric properties, after mixing the piezoelectric ceramic material, polyurethane-epoxy resin and conductive agent, a room temperature shape memory piezoelectric polymer composite bridge filling material is prepared. In the room temperature shape memory piezoelectric polymer composite bridge filling material prepared by the present invention, a polyurethane-epoxy resin containing reversible dynamic covalent disulfide bonds is used as a matrix material, a piezoelectric ceramic material is used to generate electric charge under the action of external stress, and a conductive agent is used as a medium for electrical and thermal conversion, thereby realizing the conversion of mechanical energy obtained from road vibration into electrical energy and then into thermal energy. The thermal energy directly acts on the polyurethane-epoxy resin, thereby increasing the cleavage, decomposition and recombination of the disulfide bonds. The rapid dynamic exchange reaction causes the network topology to rearrange, prompting the room temperature shape memory piezoelectric polymer composite bridge filling material to undergo shape memory recovery at room temperature, thereby overcoming the defect of the existing polymer bridge filling materials in lacking adaptive bridge deformation.

[0006] The present invention is achieved through the following technical solutions:

[0007] A method for preparing a room temperature shape memory piezoelectric polymer composite bridge filling material comprises the following steps:

[0008] In a nitrogen atmosphere, epoxy resin and 2,2'-diaminodiphenyl disulfide are mixed, and the amino group of 2,2'-diaminodiphenyl disulfide undergoes a ring-opening reaction with the epoxy group of the epoxy resin to obtain an epoxy resin precursor. 2,2'-diaminodiphenyl disulfide is used as a raw material to introduce a reversible dynamic covalent disulfide bond into the epoxy resin precursor. The epoxy resin is a bisphenol A epoxy resin, model E51. The reasons for using bisphenol A epoxy resin as a raw material are: a. Compared with other types of epoxy resins, bisphenol A epoxy resin is the epoxy resin with the largest output and the most widely used A type of epoxy resin that is cheap and readily available; b. The molecular structure of bisphenol A epoxy resin contains a bisphenol A skeleton, which gives it good heat resistance. Among them, E51 has an average epoxy value of 51, its viscosity is low, and its hardness after curing is high. It is more suitable for improving the mechanical properties of room-temperature shape memory piezoelectric polymer composite bridge filling materials. Therefore, E51 bisphenol A epoxy resin is selected; c. High-purity bisphenol A epoxy resin has low impurity content, low active content, low hydroxyl content, low viscosity and high epoxy group content. In practical applications, it has good stability, good chemical corrosion resistance and high mechanical strength.

[0009] Under a nitrogen atmosphere, 4,4-diphenylmethane diisocyanate, polyether polyol and 2,2'-diaminodiphenyl disulfide are mixed, and then prepolymerized and chain-extended to obtain a thermoplastic polyurethane prepolymer.

[0010] The epoxy resin precursor is mixed with the thermoplastic polyurethane prepolymer under a nitrogen atmosphere, so that the molecular chains of the epoxy resin precursor and the thermoplastic polyurethane prepolymer penetrate each other, and a polyurethane-epoxy resin with an interpenetrating network structure is obtained.

[0011] According to the chemical formula (Ba 0.85-2x Li x Al x Ca 0.15 )(Zr 0.1 Ti 0.9 )O3, the Ba source, the Li source, the Al source, the Ca source, the Zr source and the Ti source are weighed and mixed to obtain a raw material mixture, wherein 0 < x < 0.3; the Ba source is selected from BaCO3 (purity ≥ 99%), the Li source is selected from Li2CO3 (purity ≥ 98%), the Al source is selected from Al2O3 (purity ≥ 95%), the Ca source is selected from CaCO3 (purity ≥ 99%), the Zr source is selected from ZrO2 (purity ≥ 99%), and the Ti source is selected from TiO2 (purity ≥ 98%).

[0012] The raw material mixture is first pre-fired at 1200-1250°C for 4-6h to obtain pre-fired powder I. After ball milling of the pre-fired powder I, the pre-fired powder I is sieved through a 120-250 mesh screen to obtain pre-fired powder II with a particle size of 0.062-0.125mm. The pre-fired powder I is ball milled to promote the compatibility of the pre-fired powder I and the polyurethane-epoxy resin. The pre-fired powder II is polarized in a direct current electric field of 1-3kV / cm for 10-30min to orient the internal domains and thus improve the polarization strength, so as to obtain a piezoelectric ceramic material with piezoelectric properties.

[0013] The piezoelectric ceramic material, the polyurethane-epoxy resin and the conductive agent are mixed, and then cast and cured to obtain a room temperature shape memory piezoelectric polymer composite bridge joint filling material. The piezoelectric ceramic material generates electric charge under the action of external stress, the conductive agent converts electric energy into heat energy, the heat energy promotes the dynamic covalent bond of the polyurethane-epoxy resin to break down and recombine, the rapid dynamic exchange reaction causes the network topology structure to rearrange, and the shape memory recovery occurs.

[0014] The conductive agent is selected from conductive carbon black, acetylene black, carbon nanotubes or graphene.

[0015] Preferably, the ring-opening reaction is carried out at 110-130°C for 2-4h.

[0016] Preferably, the molar ratio of the epoxy group of the epoxy resin to the amino group of the 2,2'-diaminodiphenyl disulfide is 1.9-2.0:1.

[0017] Preferably, the prepolymerization and chain extension reaction are carried out at 110-130°C for 2-4h.

[0018] Preferably, the molar ratio of 4,4-diphenyl methane diisocyanate, polyether polyol and 2,2'-diamino diphenyl disulfide is 3:1:1.8-2.0, and outside this ratio range, the mechanical properties of the thermoplastic polyurethane prepolymer decrease, and the thermal stability decreases.

[0019] Preferably, the mixing conditions of 4,4-diphenyl methane diisocyanate, polyether polyol and 2,2'-diamino diphenyl disulfide are heating and stirring at 110-130 DEG C for 2-6 h.

[0020] Preferably, the mass percentage of the polyurethane prepolymer and the epoxy resin precursor is 55-65% and 35-45% respectively, and the sum of the mass percentage of the two is 100%. If the amount of the polyurethane prepolymer is too high, the toughness of the polyurethane-epoxy resin increases, and the mechanical properties decrease significantly, and the use conditions of the bridge expansion joint cannot be met. If the amount of the epoxy resin precursor is too high, the toughness decreases significantly, and the glass transition temperature is too high, and the self-adapting bridge deformation ability of the polyurethane-epoxy resin in the range of room temperature-60 DEG C decreases.

[0021] Preferably, the mass percentage of the piezoelectric ceramic material, the polyurethane-epoxy resin and the conductive agent is 5-40%, 59.2-94.8% and 0.2-0.8% respectively, and the sum of the mass percentage of the three is 100%. If the ceramic content is too high, the polyurethane-epoxy resin introduces too many defects, and the mechanical properties decrease significantly. If the ceramic content is too low, the piezoelectric performance is poor, and it is difficult to drive the room temperature shape memory piezoelectric polymer composite bridge joint sealing material to occur shape memory recovery. If the content of the conductive agent is too low, the complete conductive path cannot be formed inside, and the electric energy cannot be completely converted into heat energy. If the content of the conductive agent is too high, the polyurethane-epoxy resin introduces too many defects, and the mechanical properties decrease significantly.

[0022] Preferably, the curing method is: first degassing in a vacuum oven to completely eliminate bubbles, then curing at 60-90 DEG C for 10-24 h, and then curing at 100-130 DEG C for 4-8 h.

[0023] The application also protects the room temperature shape memory piezoelectric polymer composite bridge joint sealing material prepared by the above preparation method, and the room temperature shape memory piezoelectric polymer composite bridge joint sealing material has shape memory characteristics at room temperature.

[0024] The application also protects the application of the room temperature shape memory piezoelectric polymer composite bridge joint sealing material in the preparation of bridge joint sealing materials.

[0025] Compared with the prior art, the application has the following beneficial effects:

[0026] 1. The room temperature shape memory piezoelectric composite bridge joint filling material developed by the application can convert mechanical energy generated in the pavement structure into electrical energy, realize the conversion of electrical energy into thermal energy through the construction of the internal network structure of the room temperature shape memory piezoelectric composite bridge joint filling material, and further promote the shape memory recovery at room temperature, thereby effectively improving the self-adaptability of the bridge expansion joint displacement.

[0027] The application uses epoxy resin and 2,2'-diamino diphenyl disulfide as raw materials, and prepares an epoxy resin precursor based on the ring-opening reaction between the amino group of 2,2'-diamino diphenyl disulfide and the epoxy group of the epoxy resin; in addition, by using 2,2'-diamino diphenyl disulfide as a raw material, a reversible dynamic covalent bond disulfide bond is introduced to give the epoxy resin precursor certain self-healing properties.

[0028] The application uses 4,4-diphenyl methane diisocyanate, polyether polyol and 2,2'-diamino diphenyl disulfide as raw materials to prepare a thermoplastic polyurethane prepolymer, introduces an asymmetric ortho-substituted aromatic disulfide 2,2'-diamino diphenyl disulfide into the main chain, successfully controls the composition ratio of the soft segment and the hard segment of the thermoplastic polyurethane prepolymer, and introduces a reversible dynamic covalent bond disulfide bond. In terms of regulation, the soft segment is a flexible segment in the thermoplastic polyurethane prepolymer, which is composed of polyether polyol. The soft segment has good flexibility, which can improve the flexibility and wear resistance of the thermoplastic polyurethane prepolymer. The molecular weight and crystallinity of the soft segment have a significant impact on the performance of the thermoplastic polyurethane prepolymer. The hard segment is a rigid segment in the polyurethane, which is composed of 4,4-diphenyl methane diisocyanate. Compared with other alicyclic isocyanates, 4,4-diphenyl methane diisocyanate can form stronger chemical bonds, thereby improving the strength and durability of the thermoplastic polyurethane prepolymer. By controlling the mass of the chain extender 2,2'-diamino diphenyl disulfide and 4,4-diphenyl methane diisocyanate, the average length of the chain segment composed of 4,4-diphenyl methane diisocyanate and the chain extender 2,2'-diamino diphenyl disulfide in the hard segment is controlled, thereby changing the mass fraction of the hard segment and significantly affecting the structure of the soft and hard segments of the thermoplastic polyurethane prepolymer, so as to regulate the performance of the polyurethane.

[0029] The reason for using polyether polyol as a raw material is that, compared with other polyols, polyether polyol has good hydrolysis resistance and can better adapt to the use environment of the bridge expansion joint. In addition, polyether polyol has high reactivity, abundant raw material sources and low price, and is more suitable as a filling material and large-scale application in bridge expansion joints. The reason for using 4,4-diphenyl methane diisocyanate as a raw material is that 4,4-diphenyl methane diisocyanate has lower toxicity than other isocyanate materials, which can reduce the adverse effects on the environment during large-scale construction and use.

[0030] The epoxy resin precursor is mixed with the thermoplastic polyurethane prepolymer to make the molecular chains penetrate each other, so that the polyurethane-epoxy resin interpenetrating network with interpenetrating network structure is obtained. The interpenetrating network is a new polymer formed by physical entanglement of two or more polymers. The unique interpenetration and intermolecular entanglement make the excellent properties of each component synergistically blend, so that the interpenetrating polymer network exhibits excellent performance characteristics. When two homopolymers are simply mixed without any molecular entanglement, two different glass transition temperatures are observed, but in the interpenetrating polymer network, it usually has a single wide glass transition temperature, which can be effectively applied to vibration damping and energy absorption. The polyurethane-epoxy resin contains reversible dynamic covalent bond disulfide bond through structural design, which endows the polyurethane-epoxy resin with excellent shape memory characteristics. Meanwhile, based on the action of disulfide bond, the polyurethane-epoxy resin has good mechanical properties and can realize rapid self-repair at 80 DEG C.

[0031] 3. The piezoelectric ceramic material (Ba 0.85-2x Li x Al x Ca 0.15 )(Zr 0.1 Ti 0.9 )O3 is prepared by directly using carbonates (BaCO3 (99%), Li2CO3 (98%), CaCO3 (99%)) and oxides (Al2O3 (95%), ZrO2 (99%), TiO2 (98%)) to prepare barium titanate-based solid solution (Ba 0.85-2x Li x Al x Ca 0.15 )(Zr 0.1 Ti 0.9 )O3. The prepared (Ba 0.85- 2x Li x Al x Ca 0.15 )(Zr 0.1 Ti 0.9 )O3 ceramic is at the rhombohedral and orthorhombic coexisting morphotropic phase boundary at room temperature. In the piezoelectric ceramic material with perovskite structure, the orthorhombic phase has 12 polarization directions and 180°, 90°, 60°, 120° domain structures, and the rhombohedral phase has 8 polarization directions and 180°, 71°, 109° domain structures. Obviously, the ceramic material at the rhombohedral and orthorhombic coexisting morphotropic phase boundary can obtain more switchable polarization directions and non-180 domain walls, which effectively reduces the Gibbs free energy barrier and improves the piezoelectric performance of the ceramic material at room temperature; further, Li + and Al 3+The depolarization electric field generated by spontaneous polarization effectively suppresses the nucleation of antiphase domains, thereby promoting the improvement of the material's piezoelectric constant. The resulting piezoelectric ceramic material has a piezoelectric constant d33 of 448 pC / N at room temperature and a depolarization temperature of 85°C-95°C.

[0032] 4. The present invention combines polyurethane-epoxy resin, conductive agent and piezoelectric ceramic material (Ba 0.85-2x Li x Al x Ca 0.15 )(Zr 0.1 Ti 0.9 )O3 after mixing, casting, curing, to obtain the room temperature shape memory piezoelectric polymer composite bridge filling material, wherein the polyurethane-epoxy resin as the matrix material ensures the mechanical properties of the composite material while also having a certain toughness and recovery deformation; the piezoelectric ceramic material (Ba 0.85-2x Li x Al x Ca 0.15 )(Zr 0.1 Ti 0.9 )O3 gives the composite material certain piezoelectric properties, enabling it to generate electric charges under the action of external stress, thereby realizing the direct utilization of road vibration energy; the conductive agent acts as a medium for electrical and thermal conversion, forming a conductive network inside the composite material, realizing the transmission of charges generated by piezoelectric ceramics under stress, and then converting it into thermal energy and directly acting on the polyurethane-epoxy resin, increasing the decomposition and exchange rate of disulfide bonds, prompting it to undergo shape memory recovery at room temperature, and at the same time improving the shape memory and self-repairing properties of the composite material through the formation of an internal interpenetrating network structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 1 is the XRD pattern of the room temperature shape memory piezoelectric polymer composite bridge filling material prepared in Examples 1-4 of the present invention.

[0034] Figure 2 This is the infrared spectrum of the room temperature shape memory piezoelectric polymer composite bridge filling material prepared in Examples 1-4 of the present invention.

[0035] Figure 3 The following are photos showing the change in recovery angle over time under static and dynamic load conditions for the room-temperature shape memory piezoelectric polymer composite bridge filling material prepared in Example 4 of the present invention.

[0036] Figure 4 This is a diagram showing the self-repairing performance of the room-temperature shape memory piezoelectric polymer composite bridge filling material prepared in Example 4 of the present invention.

[0037] Figure 5This is a graph showing the change in the piezoelectric constant of the piezoelectric ceramic material prepared in Example 1 as the temperature changes. DETAILED DESCRIPTION

[0038] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited by the specific embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. The experimental methods described in the embodiments of the present invention are all conventional methods unless otherwise specified.

[0039] (1) Piezoelectric materials are an important system of smart materials, which can realize the conversion of mechanical energy generated by vehicle load into electrical energy. The present invention provides a piezoelectric ceramic material (Ba 0.85-2x Li x Al x Ca 0.15 )(Zr 0.1 Ti 0.9 )O3 and its preparation method, piezoelectric ceramic material (Ba 0.85-2x Li x Al x Ca 0.15 )(Zr 0.1 Ti 0.9 )O3 converts the mechanical energy generated in the pavement structure into electrical energy, and then obtains a room-temperature shape memory piezoelectric polymer composite bridge filling material by compounding it with polyurethane-epoxy resin and conductive agent. The construction of the internal network structure of the room-temperature shape memory piezoelectric polymer composite bridge filling material realizes the conversion of electrical energy into thermal energy, and then promotes shape memory recovery at room temperature. This plays an extremely important role in improving the adaptability of the displacement of bridge expansion joints and the development and application of new materials in the field of smart highways.

[0040] The piezoelectric ceramic material (Ba 0.85-2x Li x Al x Ca 0.15 )(Zr 0.1 Ti 0.9 )O3 preparation method is simple, repeatable, high yield, and has excellent room temperature piezoelectric properties.

[0041] (2) The room temperature shape memory piezoelectric polymer composite bridge filling material of the present invention has the performance of recovering shape memory at room temperature. Under static load conditions, the recovery rate at room temperature reaches 47.22%-58.33% within 1 minute at a pressure of 1.5 kPa; and it can also take into account the self-repairing properties. The repair rate is 30.5% within 5 minutes at 80°C. It is highly practical, simple to prepare, and easy to mass-produce.

[0042] (3) The polyurethane-epoxy resin is compounded with (Ba 0.83 Li 0.01 Al 0.01 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3 piezoelectric ceramic material, on the one hand, the ceramic powder is uniformly dispersed in the polyurethane-epoxy resin with a three-dimensional interpenetrating network structure to form a stable and uniform system; on the other hand, the (Ba 0.83 Li 0.01 Al 0.01 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3 piezoelectric ceramic material is compounded with the polyurethane-epoxy resin to obtain a room-temperature-responsive shape memory piezoelectric polymer composite bridge joint filling material, which overcomes the shape memory function of the shape memory polyurethane-epoxy resin that can only respond above 60 DEG C under external conditions.

[0043] The application is further explained and described below by using examples, and the details are as follows:

[0044] Example 1

[0045] A preparation method of a room-temperature shape memory piezoelectric polymer composite bridge joint filling material, comprising the following steps:

[0046] The room-temperature shape memory piezoelectric polymer composite bridge joint filling material is a polyurethane-epoxy resin-piezoelectric composite material based on (Ba 0.83 Li 0.01 Al 0.01 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3, in this embodiment, the mass percentages of the piezoelectric ceramic material, the polyurethane-epoxy resin and the conductive carbon black as the conductive agent are 5%, 94.8% and 0.2%, respectively.

[0047] S1, preparation of an epoxy resin precursor: under a nitrogen atmosphere, epoxy resin and 2,2'-diamino diphenyl disulfide are weighed according to a molar ratio of epoxy group to amino group of 2:1, heated to 110 DEG C in a four-necked flask, and mechanically stirred at a speed of 600 r / min for 4 h to obtain a viscous solution as the epoxy resin precursor; wherein the epoxy resin is a bisphenol A type epoxy resin with a model number of E51.

[0048] S2, preparation of a polyurethane prepolymer: under a nitrogen atmosphere, 4,4-diphenyl methane diisocyanate, polyether polyol and 2,2'-diamino diphenyl disulfide are weighed and mixed according to a molar ratio of 3:1:2, heated to 110 DEG C, and mechanically stirred at a speed of 600 r / min for 4 h to obtain a thermoplastic polyurethane prepolymer.

[0049] S3. Preparation of polyurethane-epoxy resin: The thermoplastic polyurethane prepolymer of step S2 was mixed with the epoxy resin precursor of step S1, with the mass percentages of the thermoplastic polyurethane prepolymer and the epoxy resin precursor being 55% and 45%, respectively. The mixture was heated to 110° C. under a nitrogen atmosphere and mechanically stirred at a rate of 800 rpm for 6 h to obtain a uniform polyurethane-epoxy resin.

[0050] S4. Preparation of piezoelectric ceramic materials: According to the molecular formula (Ba 0.83 Li 0.01 Al 0.01 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3 in a stoichiometric ratio: weigh the raw materials separately, mix them evenly, add agate balls and anhydrous ethanol, and ball mill for 12 hours, separate the agate balls, dry them at 70°C for 12 hours, and pass them through a 120-mesh sieve to obtain a raw material mixture; the raw materials are BaCO3, Li2CO3, Al2O3, CaCO3, ZrO2 and TiO2; the usage ratio of the raw material mixture, agate balls and anhydrous ethanol is 0.40g:1g:0.60mL.

[0051] The raw material mixture was pre-calcined at 1200° C. for 6 h and naturally cooled to room temperature to obtain pre-calcined powder I.

[0052] Agate balls and anhydrous ethanol were added to the pre-calcined powder I, and the mixture was ball-milled for a second time for 12 hours. After separating the agate balls, the mixture was dried at 70°C for 12 hours and passed through a 120-mesh sieve to obtain pre-calcined powder II with a particle size of 0.125 mm. The dosage ratio of pre-calcined powder I, agate balls, and anhydrous ethanol was 0.30 g:1 g:0.40 mL. The mass of the agate balls was adjusted to a ratio of 3:2:1 (diameters: 10 mm:5 mm:2 mm).

[0053] The calcined powder II was polarized at room temperature under a direct current electric field of 1 kV / cm for 30 minutes to obtain a piezoelectric ceramic material.

[0054] S5. Preparation of polyurethane-epoxy resin-piezoelectric composite material: The piezoelectric ceramic material and conductive carbon black of step S4 are added to the polyurethane-epoxy resin of step S3, and mechanically stirred at a rate of 800 r / min at 110°C for 6 hours to obtain a uniformly mixed black viscous liquid; wherein the mass percentages of piezoelectric ceramic material, polyurethane-epoxy resin, and conductive carbon black are 5%, 94.8%, and 0.2%, respectively.

[0055] Pouring: pouring the black viscous liquid of step S5 into a preheated polytetrafluoroethylene mold to obtain a polyurethane-epoxy resin-piezoelectric composite pouring body, and the size of the polyurethane-epoxy resin-piezoelectric composite pouring body is 160x20x1mm.

[0056] Curing: placing the polyurethane-epoxy resin-piezoelectric composite pouring body in a vacuum oven to degas to completely eliminate bubbles, then raising the temperature to 60℃ at a rate of 5℃ / min in the vacuum oven for 24h, then raising the temperature to 100℃ at a rate of 5℃ / min for 8h, and then cooling to room temperature to obtain a room temperature shape memory piezoelectric polymer composite bridge joint sealing material.

[0057] The shape memory performance of the room temperature shape memory piezoelectric polymer composite bridge joint sealing material prepared in Example 1 (the mass percentages of piezoelectric ceramic material, polyurethane-epoxy resin and conductive carbon black are 5%, 94.8% and 0.2% respectively) under the action of static load and static-dynamic load at room temperature 25℃ and 1.5kPa was tested, and the test method was as follows: heating the room temperature shape memory piezoelectric polymer composite bridge joint sealing material of Example 1 to 60℃, then applying an external force to fold it in half and cooling it to 0℃, fixing its temporary shape and keeping it for 5min, and finally placing the folded room temperature shape memory piezoelectric polymer composite bridge joint sealing material at a static water depth of 15cm, according to p=ρgh, at this time the room temperature shape memory piezoelectric polymer composite bridge joint sealing material is subjected to a pressure of 1.5kPa in water, and its shape memory recovery performance is observed under the action of no ultrasound (static load) and ultrasound with a power of 40kHz (static-dynamic load) respectively. The test results are shown in Table 1.

[0058] Table 1: Recovery angle and recovery rate of Example 1

[0059]

[0060] The results in Table 1 show that the prepared shape memory piezoelectric polymer composite bridge joint sealing material can achieve a shape memory recovery rate of 58.83% and 66.67% within 1min under the action of static load and static-dynamic load at 25℃ and 1.5kPa, which can effectively alleviate the problem of insufficient self-adaptive bridge deformation ability of the room temperature shape memory piezoelectric polymer composite bridge joint sealing material at room temperature.

[0061] Example 2

[0062] A preparation method of a room temperature shape memory piezoelectric polymer composite bridge joint sealing material, comprising the following steps:

[0063] The room temperature shape memory piezoelectric polymer composite bridge joint sealing material is based on (Ba 0.83 Li 0.01 Al 0.01 Ca 0.15)(Zr 0.1 Ti 0.9 )O3's polyurethane-epoxy resin-piezoelectric composite material, in this embodiment, the mass percentages of piezoelectric ceramic material, polyurethane-epoxy resin and conductive agent conductive carbon black are 10%, 89.6% and 0.4% respectively.

[0064] S1. Preparation of epoxy resin precursor: Under a nitrogen atmosphere, epoxy resin and 2,2'-diaminodiphenyl disulfide are weighed in a molar ratio of epoxy group to amino group of 2:1, heated to 120°C in a four-necked flask, and mechanically stirred at a rate of 500 r / min for 4 hours to obtain a viscous solution, which is an epoxy resin precursor; the epoxy resin is bisphenol A epoxy resin, model E51.

[0065] S2. Preparation of a polyurethane prepolymer: Under a nitrogen atmosphere, 4,4-diphenylmethane diisocyanate, polyether polyol, and 2,2'-diaminodiphenyl disulfide were weighed in a molar ratio of 3:1:2, mixed, heated to 120° C., and mechanically stirred at 500 rpm for 4 h to obtain a thermoplastic polyurethane prepolymer;

[0066] S3. Preparation of polyurethane-epoxy resin: The thermoplastic polyurethane prepolymer of step S2 was mixed with the epoxy resin precursor of step S1, with the mass percentages of the thermoplastic polyurethane prepolymer and the epoxy resin precursor being 58% and 42%, respectively. The mixture was heated to 120° C. under a nitrogen atmosphere and mechanically stirred at a rate of 500 rpm for 4 h to obtain a uniform polyurethane-epoxy resin.

[0067] S4. Preparation of piezoelectric ceramic materials: According to the molecular weight (Ba 0.83 Li 0.01 Al 0.01 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3 in a stoichiometric ratio: weigh the raw materials separately, mix them evenly, add agate balls and anhydrous ethanol, ball mill for 20 hours, separate the agate balls, dry them at 75°C for 12 hours, and pass them through a 120-mesh sieve to obtain a raw material mixture; the raw materials are BaCO3, Li2CO3, Al2O3, CaCO3, ZrO2 and TiO2; the usage ratio of the raw material mixture, agate balls and anhydrous ethanol is 0.40g:1g:0.60mL.

[0068] The raw material mixture was pre-calcined at 1250° C. for 5 h and naturally cooled to room temperature to obtain pre-calcined powder I.

[0069] Agate balls and anhydrous ethanol were added to the pre-calcined powder I, and the mixture was ball-milled for a second time for 20 hours. After separating the agate balls, the mixture was dried at 75°C for 12 hours and passed through a 250-mesh sieve to obtain a pre-calcined powder II with a particle size of 0.062 mm. The dosage ratio of the pre-calcined powder I, agate balls, and anhydrous ethanol was 0.30 g:1 g:0.40 mL. The mass of the agate balls was adjusted to a ratio of 3:2:1 for diameters of 10 mm:5 mm:2 mm.

[0070] The calcined powder II was polarized at room temperature under a direct current electric field of 3 kV / cm for 10 minutes to obtain a piezoelectric ceramic material.

[0071] S5. Preparation of polyurethane-epoxy resin-piezoelectric composite material: add the piezoelectric ceramic material and conductive carbon black of step S4 to the polyurethane-epoxy resin of step S3, and mechanically stir at a rate of 600 r / min at 120°C for 4 hours to obtain a uniformly mixed black viscous liquid; wherein the mass percentages of piezoelectric ceramic material, polyurethane-epoxy resin, and conductive carbon black are 10%, 89.6%, and 0.4%, respectively.

[0072] Casting: The black viscous liquid in step S5 is poured into a preheated polytetrafluoroethylene mold to obtain a polyurethane-epoxy resin-piezoelectric composite material casting body. The size of the polyurethane-epoxy resin-piezoelectric composite material casting body is 160×20×1 mm.

[0073] Curing: The polyurethane-epoxy resin-piezoelectric composite casting was placed in a vacuum oven for degassing to completely eliminate bubbles. The temperature was then raised to 80°C at a heating rate of 8°C / min in the vacuum oven for aging for 12 hours, and then raised to 120°C at a heating rate of 8°C / min for curing for 6 hours. The casting was then cooled to room temperature to obtain a room temperature shape memory piezoelectric polymer composite bridge filling material.

[0074] The shape memory performance of the room-temperature shape memory piezoelectric polymer composite bridge filler prepared in Example 2 (with piezoelectric ceramic material, polyurethane-epoxy resin, and conductive carbon black in the mass percentages of 10%, 89.6%, and 0.4%, respectively) was tested at room temperature (30°C) under a static load of 1.5 kPa and under both static and dynamic loads. The test method was as follows: the room-temperature shape memory piezoelectric polymer composite bridge filler of Example 2 was heated to 60°C, then folded in half with an external force and cooled to 0°C. The temporary shape was fixed and maintained for 5 minutes. Finally, the folded material was placed in still water at a depth of 15 cm. Based on p = ρgh, the pressure applied to the material in the water was 1.5 kPa. The shape memory recovery performance was observed under no ultrasound (static load) and under 40 kHz ultrasound (static and dynamic load). The test results are shown in Table 2.

[0075] Table 2: Recovery angle and recovery rate of Example 2

[0076]

[0077] The results in Table 2 show that the shape memory recovery rate of the prepared shape memory piezoelectric polymer composite bridge filling material can reach 47.22% and 66.67% within 1 minute under static load and static and dynamic load at 30°C and 1.5 kPa, which can effectively alleviate the problem of insufficient adaptive bridge deformation ability of room temperature shape memory piezoelectric polymer composite bridge filling material at room temperature.

[0078] Example 3

[0079] A method for preparing a room temperature shape memory piezoelectric polymer composite bridge filling material comprises the following steps:

[0080] Room temperature shape memory piezoelectric polymer composite bridge filling material is based on (Ba 0.83 Li 0.01 Al 0.01 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3's polyurethane-epoxy resin-piezoelectric composite material, the mass percentages of the piezoelectric ceramic material, polyurethane-epoxy resin, and conductive agent conductive carbon black are 20%, 79.5%, and 0.5%, respectively.

[0081] S1. Preparation of epoxy resin precursor: Under a nitrogen atmosphere, epoxy resin and 2,2'-diaminodiphenyl disulfide were weighed in a molar ratio of epoxy group to amino group of 2:1, heated to 125°C in a four-necked flask, and mechanically stirred at a rate of 400 r / min for 3 h to obtain a viscous solution, which is an epoxy resin precursor; the epoxy resin is bisphenol A epoxy resin, model E51.

[0082] S2. Preparation of polyurethane prepolymer: Under a nitrogen atmosphere, 4,4-diphenylmethane diisocyanate, polyether polyol and 2,2'-diaminodiphenyl disulfide were weighed in a molar ratio of 3:1:2 and mixed, heated to 125°C, and mechanically stirred at a rate of 400 r / min for 3 h to obtain a thermoplastic polyurethane prepolymer.

[0083] S3. Preparation of polyurethane-epoxy resin: The thermoplastic polyurethane prepolymer of step S2 was mixed with the epoxy resin precursor obtained in step S1, with the mass percentages of the thermoplastic polyurethane prepolymer and the epoxy resin precursor being 60% and 40%, respectively. The mixture was heated to 125° C. under a nitrogen atmosphere and mechanically stirred at a rate of 500 rpm for 5 h to obtain a uniform polyurethane-epoxy resin.

[0084] S4, Preparation of piezoelectric ceramic material: raw materials were weighed according to stoichiometric ratio of formula (Ba 0.83 Li 0.01 Al 0.01 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3, mixed uniformly, added with agate balls and anhydrous ethanol, ball-milled for 18 h, separated the agate balls, dried at 80°C for 10 h, and sieved through 120 mesh to obtain a raw material mixture; the raw materials were BaCO3, Li2CO3, Al2O3, CaCO3, ZrO2, and TiO2; the amount ratio of the raw material mixture, agate balls, and anhydrous ethanol was 0.40 g: 1 g: 0.60 mL;

[0085] The raw material mixture was pre-fired at a temperature of 1200°C for 5 h, and naturally cooled to room temperature to obtain pre-fired powder I.

[0086] Agate balls and anhydrous ethanol were added to the pre-fired powder I, and secondary ball-milling was performed for 18 h. After separating the agate balls, drying was performed at 80°C for 10 h, and sieving was performed through 200 mesh to obtain pre-fired powder II with a particle size of 0.075 mm; the amount ratio of the pre-fired powder I, agate balls, and anhydrous ethanol was 0.30 g: 1 g: 0.40 mL; the mass of the agate balls was proportioned according to a diameter of 10 mm: 5 mm: 2 mm = 3:2:1.

[0087] The pre-fired powder II was polarized at room temperature under a direct current electric field of 2 kV / cm for 20 min to obtain a piezoelectric ceramic material.

[0088] S5, Preparation of polyurethane-epoxy resin-piezoelectric composite material: the piezoelectric ceramic material of step S4 and conductive carbon black were jointly added to the polyurethane-epoxy resin of step S3, and mechanical stirring was performed at 125°C at a speed of 500 r / min for 5 h to obtain a black viscous liquid that was uniformly mixed; the mass percentage of the piezoelectric ceramic material, polyurethane-epoxy resin, and conductive carbon black was 20%, 79.5%, and 0.5%, respectively.

[0089] Pouring: the black viscous liquid of step S5 was poured into a preheated polytetrafluoroethylene mold to obtain a polyurethane-epoxy resin-piezoelectric composite material pouring body, and the size of the polyurethane-epoxy resin-piezoelectric composite material pouring body was 160×20×1 mm.

[0090] Curing: the polyurethane-epoxy resin-piezoelectric composite material pouring body was placed in a vacuum oven for degassing to completely eliminate bubbles, and then the temperature was raised to 70°C at a rate of 6°C / min for 18 h, and then raised to 125°C at a rate of 6°C / min for 5 h, and then cooled to room temperature to obtain a room temperature shape memory piezoelectric polymer composite bridge joint filling material.

[0091] The shape memory performance of the room-temperature shape memory piezoelectric polymer composite bridge filler prepared in Example 3 (with piezoelectric ceramic material, polyurethane-epoxy resin, and conductive carbon black in the mass percentages of 20%, 79.5%, and 0.5%, respectively) was tested at room temperature (30°C) under a static load of 1.5 kPa and under both static and dynamic loads. The test method was as follows: the room-temperature shape memory piezoelectric polymer composite bridge filler of Example 3 was heated to 60°C, then folded in half with an external force and cooled to 0°C. The temporary shape was fixed and maintained for 5 minutes. Finally, the folded material was placed in still water at a depth of 15 cm. Based on p = ρgh, the pressure applied to the material in the water was 1.5 kPa. The shape memory recovery performance was observed under no ultrasound (static load) and under 40 kHz ultrasound (static and dynamic load). The test results are shown in Table 3.

[0092] Table 3: Recovery angle and recovery rate of Example 3

[0093]

[0094] The results in Table 3 show that the shape memory recovery rate of the prepared shape memory piezoelectric polymer composite bridge filling material can reach 50% and 67.78% within 1 minute under static load and static and dynamic load at 30°C and 1.5kPa, which can effectively improve the problem of insufficient adaptive bridge deformation ability of room temperature shape memory piezoelectric polymer composite bridge filling materials at room temperature.

[0095] Example 4

[0096] A method for preparing a room temperature shape memory piezoelectric polymer composite bridge filling material comprises the following steps:

[0097] Room temperature shape memory piezoelectric polymer composite bridge filling material is based on (Ba 0.83 Li 0.01 Al 0.01 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3's polyurethane-epoxy resin-piezoelectric composite material, the mass ratios of the piezoelectric ceramic material, polyurethane-epoxy resin, and conductive agent conductive carbon black are 40%, 59.2%, and 0.8%, respectively.

[0098] S1, Preparation of epoxy resin precursor: under the nitrogen atmosphere, epoxy resin and 2,2'-diamino diphenyl disulfide were weighed according to the molar ratio of epoxy group and amino group 2:1, heated to 130 DEG C in a four-necked flask, and mechanically stirred at a speed of 300 r / min for 2h to obtain a viscous solution, which was the epoxy resin precursor; wherein the epoxy resin was bisphenol A type epoxy resin, model E51.

[0099] S2, Preparation of polyurethane prepolymer: under the nitrogen atmosphere, 4,4-diphenyl methane diisocyanate, polyether polyol and 2,2'-diamino diphenyl disulfide were weighed and mixed according to the molar ratio 3:1:2, heated to 130 DEG C, and mechanically stirred at a speed of 300 r / min for 2h to obtain a thermoplastic polyurethane prepolymer.

[0100] S3, Preparation of polyurethane-epoxy resin: the thermoplastic polyurethane prepolymer of step S2 was mixed with the epoxy resin precursor obtained in step S1, the mass percentage of the thermoplastic polyurethane prepolymer and the epoxy resin precursor was 65% and 35% respectively, heated to 130 DEG C under the nitrogen atmosphere, and mechanically stirred at a speed of 400 r / min for 2h to obtain a uniform polyurethane-epoxy resin.

[0101] S4, Preparation of piezoelectric ceramic material: according to the stoichiometric ratio of the molecular formula (Ba 0.83 Li 0.01 Al 0.01 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3, raw materials were weighed and mixed uniformly, agate balls and anhydrous ethanol were added, ball milling for 24h, the agate balls were separated, dried at a temperature of 80 DEG C for 10h, and sieved through a 120 mesh screen to obtain a raw material mixture; the raw materials were BaCO3, Li2CO3, Al2O3, CaCO3, ZrO2 and TiO2; the amount ratio of the raw material mixture, the agate balls and the anhydrous ethanol was 0.40g:1g:0.60mL.

[0102] The raw material mixture was pre-fired at a temperature of 1250 DEG C for 4h, and naturally cooled to room temperature to obtain a pre-fired powder I.

[0103] The pre-fired powder I was added with agate balls and anhydrous ethanol, and ball-milled for 24h, then the agate balls were separated, dried at a temperature of 80 DEG C for 10h, and sieved through a 250 mesh screen to obtain a pre-fired powder II with a particle size of 0.062mm; the amount ratio of the pre-fired powder I, the agate balls and the anhydrous ethanol was 0.30g:1g:0.40mL; the mass of the agate balls was proportioned according to the diameter 10mm:5mm:2mm=3:2:1.

[0104] The calcined powder II was polarized at room temperature under a direct current electric field of 3 kV / cm for 10 minutes to obtain a piezoelectric ceramic material.

[0105] S5. Preparation of polyurethane-epoxy resin-piezoelectric composite material: add the piezoelectric ceramic material and conductive carbon black of step S4 to the polyurethane-epoxy resin of step S3, and mechanically stir at 130°C and a rate of 400 r / min for 2 hours to obtain a uniformly mixed black viscous liquid; wherein the mass percentages of piezoelectric ceramic material, polyurethane-epoxy resin, and conductive carbon black are 40%, 59.2%, and 0.8%, respectively.

[0106] Casting: The black viscous liquid in step S5 is poured into a preheated polytetrafluoroethylene mold to obtain a polyurethane-epoxy resin-piezoelectric composite material casting body. The size of the polyurethane-epoxy resin-piezoelectric composite material casting body is 160×20×1 mm.

[0107] Curing: The polyurethane-epoxy resin-piezoelectric composite casting was placed in a vacuum oven for degassing to completely eliminate bubbles. The casting was then heated to 90°C at a heating rate of 10°C / min in the vacuum oven for 10 hours, and then heated to 130°C at a heating rate of 10°C / min for 4 hours. The casting was then cooled to room temperature to obtain a room temperature shape memory piezoelectric polymer composite bridge filling material.

[0108] The shape memory performance of the room-temperature shape memory piezoelectric polymer composite bridge filler prepared in Example 4 (with piezoelectric ceramic material, polyurethane-epoxy resin, and conductive carbon black in the mass percentages of 40%, 59.2%, and 0.8%, respectively) was tested at room temperature (30°C) under a static load of 1.5 kPa and under both static and dynamic loads. The test method was as follows: the room-temperature shape memory piezoelectric polymer composite bridge filler of Example 4 was heated to 60°C, then folded in half with an external force and cooled to 0°C. The temporary shape was fixed and maintained for 5 minutes. Finally, the folded material was placed in still water at a depth of 15 cm. Based on p = ρgh, the pressure applied to the material in the water was 1.5 kPa. The shape memory recovery performance was observed under no ultrasound (static load) and under 40 kHz ultrasound (static and dynamic load). The test results are shown in Table 4.

[0109] Table 4: Response angle and response rate of Example 4

[0110]

[0111] The results in Table 4 show that the shape memory piezoelectric polymer composite bridge joint filling material prepared has shape memory recovery rates of 55.56% and 69.44% under the action of a static load of 1.5 kPa and static and dynamic loads at 30°C within 1 min, which can effectively solve the problem of insufficient self-adaptive bridge deformation capacity of the room temperature shape memory piezoelectric polymer composite bridge joint filling material at room temperature.

[0112] Figure 1 The XRD pattern of the polyurethane-epoxy resin-piezoelectric composite material prepared in Embodiment 1-Embodiment 4 of the present application is shown in Figure 1. Figure 1 It can be seen that the room temperature shape memory piezoelectric polymer composite bridge joint filling material prepared in Embodiment 1-Embodiment 4 has obvious crystalline and amorphous regions, the amorphous region has a wide diffraction peak at 14.08°, indicating that there is an amorphous diffraction peak in the polyurethane-epoxy resin-piezoelectric composite material, and the scattering at 14.08° is attributed to the scattering of the hard segment phase in the thermoplastic polyurethane prepolymer; the crystalline region has sharp diffraction peaks, such as at 31° and 38°, which refer to the (Ba 0.83 Li 0.01 Al 0.01 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3 ceramic diffraction peak. It shows that the piezoelectric phase ceramic (Ba 0.83 Li 0.01 Al 0.01 Ca 0.15 )(Zr 0.1 Ti 0.9 )O3 and the conductive phase conductive carbon black are uniformly distributed in the matrix polymer polyurethane-epoxy resin to form a uniform and stable system. The existence of the crystalline region helps the shape fixing property, and the amorphous region promotes the shape recovery property.

[0113] Figure 2 The infrared spectrum of the polyurethane-epoxy resin-piezoelectric composite material prepared in Embodiment 1-Embodiment 4 of the present application is shown in Figure 2. Figure 2 It can be seen that there is no obvious chemical interaction between the polyurethane-epoxy resin and the piezoelectric phase ceramic in the room temperature shape memory piezoelectric polymer composite bridge joint filling material prepared in Embodiment 1-Embodiment 4, and the profiles of all the polyurethane-epoxy resin, piezoelectric phase ceramic and polyurethane-epoxy resin-piezoelectric composite material are almost the same, and there is no obvious change in the infrared spectrum, so there is no obvious chemical interaction.

[0114] However, there is a certain bonding effect between the polyurethane-epoxy resin and the conductive phase conductive carbon black, and the infrared spectrum shows that the peak at 1700 cm -1 and 1730 cm -1The change in the diffraction peak intensity at indicates that the bonding interaction involves hydrogen bonding. The presence of hydrogen bonding improves the interfacial connection between the conductive carbon black and the polyurethane-epoxy resin. Furthermore, since the conductive carbon black, thermoplastic polyurethane prepolymer, and epoxy resin precursor all form hydrogen bonds, the presence of hydrogen bonding likely promotes the aggregation of hard segments and microphase separation between the hard and soft segments, thereby enhancing shape memory and mechanical properties.

[0115] Combined with Table 4 and Figure 3 It is concluded that piezoelectric phase ceramics (Ba 0.83 Li 0.01 Al 0.01 Ca 0.15 )(Zr 0.1 Ti 0.9 The piezoelectric effect provided by O3 facilitates the shape memory recovery of the polyurethane-epoxy-piezoelectric composite. This is likely due to the immense pressure of the driving load stimulating the piezoelectric activity of the polyurethane-epoxy-piezoelectric composite, generating a large amount of electrical energy. With the help of the conductive filler, this electrical energy is largely converted into heat, which softens the hard phase and increases the rate of disulfide bond exchange, contributing to the shape memory.

[0116] Figure 4 This figure shows the self-repair performance of the room-temperature shape memory piezoelectric polymer composite bridge caulking material prepared in Example 4 of the present invention. The self-repair test method involved scratching the surface of the room-temperature shape memory piezoelectric polymer composite bridge caulking material of Example 4 with a width of 92 px. The material was then heated at 80°C and its self-repair performance was monitored by observing the change in the scratch width over 15 minutes. The results showed that the repair rate within 15 minutes at 80°C was 30.5%, representing a repair rate of 64 / 92 × 100%.

[0117] via Figure 5 It can be seen that the piezoelectric constant d33 of the piezoelectric ceramic material can reach 448pC / N at room temperature, and its depolarization temperature can reach 85℃-95℃. The ceramic will not depolarize and fail within the temperature range of the bridge expansion joint.

[0118] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications of the present invention fall within the scope of the claims and their equivalents, such changes and modifications are intended to be included.

Claims

1. A method for preparing a room temperature shape memory piezoelectric polymer composite bridge filling material, characterized in that: The steps include: In a nitrogen atmosphere, epoxy resin and 2,2'-diaminodiphenyl disulfide are mixed, and the amino group of 2,2'-diaminodiphenyl disulfide undergoes a ring-opening reaction with the epoxy group of the epoxy resin to obtain an epoxy resin precursor; Under a nitrogen atmosphere, 4,4-diphenylmethane diisocyanate, polyether polyol and 2,2'-diaminodiphenyl disulfide are mixed, and then prepolymerized and chain-extended to obtain a thermoplastic polyurethane prepolymer; the molar ratio of 4,4-diphenylmethane diisocyanate, polyether polyol and 2,2'-diaminodiphenyl disulfide is 3:1:1.8-2; Under a nitrogen atmosphere, an epoxy resin precursor and a thermoplastic polyurethane prepolymer are mixed so that the molecular chains of the epoxy resin precursor and the thermoplastic polyurethane prepolymer interpenetrate each other to obtain a polyurethane-epoxy resin having an interpenetrating network structure; the mass percentages of the polyurethane prepolymer and the epoxy resin precursor are 55%-65% and 35%-45%, respectively, and the sum of the mass percentages of the two is 100%; According to the chemical formula (Ba 0.85-2x Li x Al x Ca 0.15 )(Zr 0.1 Ti 0.9 )O3 weigh a Ba source, a Li source, an Al source, a Ca source, a Zr source, and a Ti source, and mix them to obtain a raw material mixture, wherein 0<x<0.3; The raw material mixture is pre-calcined at 1200° C. to 1250° C. for 4 to 6 hours to obtain pre-calcined powder I, the pre-calcined powder I is ball-milled to obtain pre-calcined powder II with a particle size of 0.062 mm to 0.125 mm, and the pre-calcined powder II is polarized in a DC electric field of 1 kV / cm to 3 kV / cm for 10 to 30 minutes to align the internal electric domains, thereby obtaining a piezoelectric ceramic material with piezoelectric properties; A piezoelectric ceramic material, a polyurethane-epoxy resin, and a conductive agent are mixed, then cast and cured to produce a room-temperature shape memory piezoelectric polymer composite bridge caulking material. The piezoelectric ceramic material generates an electric charge under the action of external stress, and the conductive agent converts the electrical energy into thermal energy. Under the action of thermal energy, the dynamic covalent disulfide bonds of the polyurethane-epoxy resin undergo a dynamic exchange reaction, resulting in the breakage, decomposition, and recombination of the dynamic covalent disulfide bonds, which in turn leads to shape memory recovery. The mass percentages of the piezoelectric ceramic material, the polyurethane-epoxy resin and the conductive agent are 5%-40%, 59.2%-94.8% and 0.2%-0.8% respectively, and the sum of the mass percentages of the three is 100%.

2. The method for preparing a room temperature shape memory piezoelectric polymer composite bridge filling material according to claim 1, characterized in that: The conditions for the ring-opening reaction are: heating and stirring at 110°C-130°C for 2h-4h.

3. The method for preparing a room temperature shape memory piezoelectric polymer composite bridge filling material according to claim 1, characterized in that: The molar ratio of the epoxy group in the epoxy resin to the amino group in the 2,2'-diaminodiphenyl disulfide is 1.9-2.0:

1.

4. The method for preparing a room temperature shape memory piezoelectric polymer composite bridge filling material according to claim 1, characterized in that: The conditions for the prepolymerization and chain extension reaction are: heating and stirring at 110°C-130°C for 2h-4h.

5. A room temperature shape memory piezoelectric polymer composite bridge filling material prepared by the preparation method according to any one of claims 1 to 4, characterized in that: Room temperature shape memory piezoelectric polymer composite bridge filling material has shape memory properties at room temperature.

6. Use of the room temperature shape memory piezoelectric polymer composite bridge filling material according to claim 5 in the preparation of bridge filling materials.

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