Phase separation based buoyancy bead anchored triphasic composites, methods of making and applications thereof

Abstract

The application discloses a kind of based on phase separation's floating bead anchoring three-phase composite material and its preparation method and application, the preparation method includes: premix liquid and prepolymer system are mixed to be uniform, obtain first mixed system, wherein, premix liquid includes: fly ash floating bead, thermoplastic resin and organic solvent, prepolymer system includes: prepolymer, prepolymer is polymerized by thermosetting resin monomer and crosslinking agent;First mixed system is carried out stepwise vacuum treatment, obtain based on phase separation's floating bead anchoring three-phase composite material precursor;Based on phase separation's floating bead anchoring three-phase composite material precursor is segmented curing, obtain based on phase separation's floating bead anchoring three-phase composite material.The application utilizes the hollow structure characteristics of fly ash floating bead and thermoplastic resin produces synergistic effect, realizes material light weight while also having good mechanical properties, thermal performance and flame retardant performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high polymer composite materials, and particularly relates to a phase separation-based floating bead anchoring three-phase composite material and a preparation method and application thereof. BACKGROUND

[0002] Thermosetting resin materials, including but not limited to epoxy resin materials, unsaturated polyester resin materials and phenolic resin materials, etc., have an irreplaceable important position in high-end manufacturing fields such as aerospace, electronic packaging and automobile manufacturing due to their excellent mechanical properties, chemical corrosion resistance and dimensional stability. However, the high cross-linking density network structure formed after the curing of such materials, although endowing the materials with excellent rigidity, also leads to the inherent defect of large brittleness (i.e. poor toughness). Especially under impact load conditions, the material is prone to crack propagation, which seriously affects the reliability of its engineering application.

[0003] For the toughening and reinforcing modification of thermosetting resins, currently, two technical routes are mainly adopted: one is to introduce thermoplastic resins into the thermosetting resins, and the other is to add inorganic rigid fillers. However, both of these two methods have obvious technical limitations: due to the characteristics of thermoplastic resins, the introduction of thermoplastic resins, although can improve the fracture toughness of the composite material, will inevitably reduce the stiffness and strength of the composite material, showing a clear "toughening and weakening" effect; while the introduction of inorganic rigid fillers (such as silicon dioxide, carbon fiber, etc.) can improve the strength and modulus of the composite material, but often further worsens the brittleness of the composite material, showing a typical "strengthening and embrittlement" phenomenon. More notably, due to the significant density difference between inorganic rigid fillers and thermosetting resins, inorganic rigid fillers are prone to floating or settling during the preparation of the composite material, leading to uneven dispersion, which not only affects the mechanical properties of the composite material, but also causes anisotropy of the performance.

[0004] As a special functional filler, fly ash floating bead has the following characteristic advantages: 1) unique hollow spherical structure, which can realize material lightweight and improve stress distribution; 2) main components are SiO2 and Al2O3, which can significantly improve the heat resistance and flame retardance of the composite material, so the technical personnel in the field try to introduce fly ash floating bead into thermosetting resin. However, in the prior art, fly ash floating bead still has deficiencies in modifying thermosetting resin, on the one hand, the chemical inertness of the surface of fly ash floating bead leads to insufficient adhesion strength with thermosetting resin; on the other hand, the dispersion uniformity of fly ash floating bead in thermosetting resin is difficult to control, and stress concentration points are easily formed. These technical defects seriously restrict the application effect of fly ash floating bead in the modification of thermosetting resin such as epoxy resin. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application aims to provide a preparation method of a phase separation-based floating bead anchoring three-phase composite material.

[0006] Another object of the present application is to provide the phase separation-based floating bead anchoring three-phase composite material obtained by the above preparation method, wherein the "three phases" in the floating bead anchoring three-phase composite material respectively refer to fly ash floating beads, a thermosetting resin-rich phase and a thermoplastic resin-rich phase, and the fly ash floating beads are anchored between the two-phase interface formed by the thermosetting resin-rich phase and the thermoplastic resin-rich phase.

[0007] The object of the present application is achieved by the following technical solutions.

[0008] The present application provides a preparation method of a phase separation-based floating bead anchoring three-phase composite material, comprising the following steps:

[0009] Step 1: mixing a premix liquid and a prepolymer system uniformly to obtain a first mixed system, wherein the premix liquid comprises fly ash floating beads, a thermoplastic resin and an organic solvent, and the prepolymer system comprises a prepolymer, which is polymerized from a thermosetting resin monomer and a crosslinking agent, and the mass ratio of the fly ash floating beads, the thermoplastic resin, the thermosetting resin monomer and the crosslinking agent is (3-30):(10-20):(70-80):(20-30);

[0010] The thermosetting resin monomer is an epoxy monomer, and the epoxy monomer is at least one of a bisphenol A type epoxy resin monomer, a bisphenol F type epoxy resin monomer, a hydrogenated bisphenol A type epoxy resin monomer and a phenolic epoxy resin monomer.

[0011] The thermoplastic resin is a polysulfone resin, and the polysulfone resin is at least one of polyether sulfone (PES) and polyphenyl sulfone (PPSU).

[0012] In step 1, the crosslinking agent is at least one of a polyamine crosslinking agent, a polybasic anhydride crosslinking agent and a polyphenol crosslinking agent, and is preferably a polyamine crosslinking agent.

[0013] In step 1, the premix liquid at room temperature and the prepolymer system at 50-90°C (preferably 65-75°C) are mixed and stirred uniformly to obtain the first mixed system. The stirring speed is 300-1000 rpm (preferably 400-600 rpm), and the stirring time is 0.25-1 hour (preferably 0.5 hour).

[0014] In step 1, the average particle size of the fly ash floating beads is 10-80 μm, and is preferably 20-60 μm.

[0015] In step 1, the ratio of the mass fraction of the thermoplastic resin to the volume fraction of the organic solvent is 1: (4-6), the unit of the mass fraction is g, and the unit of the volume fraction is mL.

[0016] In step 1, the organic solvent is a mixture of one or more of dichloromethane, chloroform, chloroform, N, N-dimethylformamide and tetrahydrofuran.

[0017] In step 1, the method for obtaining the premix solution comprises: mixing the thermoplastic resin and the organic solvent until uniform, adding fly ash floating beads, and mixing until uniform to obtain the premix solution.

[0018] In the above technical solution, the thermoplastic resin and the organic solvent are mixed at 15-40°C (preferably 20-30°C), stirred until uniform, and fly ash floating beads are added and stirred until uniform. The stirring speed is 200-800 rpm (preferably 300-500 rpm), and the stirring time is 0.5-4 hours.

[0019] In step 1, the method for obtaining the prepolymer system comprises: preheating the thermosetting resin monomer to 50-150°C (preferably 120-140°C), adding a crosslinking agent, and stirring at 50-150°C (preferably 120-140°C) until a homogeneous transparent system is formed to obtain a prepolymer system containing a prepolymer.

[0020] Step 2, the first mixed system is subjected to a stepwise vacuum treatment to obtain a floating bead anchoring three-phase composite material precursor based on phase separation;

[0021] In step 2, the stepwise vacuum treatment comprises: vacuum treatment at 60-80°C for 1-3 hours under vacuum environment (vacuum degree ≤-0.08 MPa), vacuum treatment at 130-150°C for 0.25-6 hours, pouring into a mold, and finally vacuum treatment at 130-150°C for 0.25-6 hours.

[0022] Step 3, the floating bead anchoring three-phase composite material precursor based on phase separation is subjected to segmented curing (to cure the prepolymer to form a thermosetting resin) to obtain a floating bead anchoring three-phase composite material based on phase separation.

[0023] In step 3, the segmented curing comprises: first curing at 70-150°C for 1-10 hours, and then curing at 100-185°C for 1-10 hours. Preferably, first curing at 135-145°C for 3-5 hours, and then curing at 175-185°C for 1-3 hours.

[0024] The floating bead anchoring three-phase composite material based on phase separation obtained by the above preparation method.

[0025] Application of the phase separation based floating bead anchored three-phase composite material in improving tensile strength, impact strength, heat insulation performance and / or flame retardant performance of the material.

[0026] In the above technical solution, the heat insulation performance is characterized by the heat transfer coefficient, and the flame retardant performance is characterized by the limiting oxygen index.

[0027] In the above technical solution, the tensile strength of the phase separation based floating bead anchored three-phase composite material is 70-90 MPa; the impact strength is 25-40 kJ / m 2 ; the heat transfer coefficient is 0.05-0.15 W / (m·K); and the limiting oxygen index is ≥24.0%.

[0028] Application of the phase separation based floating bead anchored three-phase composite material in aerospace structural parts, electronic packaging materials and flame retardant building materials.

[0029] Compared with the prior art, the application has the following beneficial effects:

[0030] 1. The application utilizes the hollow structure characteristics of fly ash floating beads and the synergistic effect of thermoplastic resins, realizes lightweight of the material (density 1250-1600 kg / m 3 ), and also has good mechanical properties (tensile strength 70-90 MPa; impact strength 25-40 kJ / m 2 ), thermal properties (heat transfer coefficient 0.05-0.15 W / (m·K)) and flame retardant properties (limiting oxygen index ≥24.0%, first residual flame time (self-extinguishing time) <150 seconds, and no molten droplets).

[0031] 2.The application adopts a process route of premixing liquid and prepolymer system blending, stepwise vacuum treatment and segmented curing, first, a premixing liquid is prepared by mixing fly ash floating beads, thermoplastic resin and organic solvent to perform surface wetting and coating pretreatment on the fly ash floating beads, effectively improving the compatibility of fly ash floating beads and thermoplastic resin; then, the premixing liquid and the prepolymer system are blended to obtain a first mixed system, the compatibility of the prepolymer and the thermoplastic resin in the first mixed system gradually deteriorates with the increase of the polymerization degree, when reaching the thermodynamic unstable critical point, phase separation is induced, then stepwise vacuum treatment is performed to completely remove the bubbles in the first mixed system and eliminate local enrichment, laying a foundation for the uniform dispersion of fly ash floating beads; finally, the prepolymer is cured through a segmented curing process of precise temperature and time control to form a thermosetting resin (the thermosetting resin based on epoxy monomer belongs to epoxy resin material), in-situ forming a microphase structure, so that the fly ash floating beads are firmly captured and fixed by the microphase structure, thereby realizing the high uniformity and stable dispersion of fly ash floating beads in thermoplastic resin and thermosetting resin. At the same time, the thermoplastic resin and the fly ash floating beads have a synergistic mechanism: the thermoplastic resin-rich phase realizes energy dissipation through plastic deformation, and the fly ash floating beads produce a cavity expansion effect to disperse stress by virtue of their unique hollow structure, realizing the synchronous improvement of the strength (characterized by tensile strength) and toughness (characterized by impact strength) of the floating bead anchoring three-phase composite material based on phase separation, breaking through the performance bottleneck of traditional lightweight materials "strengthening and embrittlement, toughening and weakening", so that the floating bead anchoring three-phase composite material based on phase separation has the properties of lightweight, high toughness, high strength, excellent flame retardant performance and excellent thermal insulation performance. In addition, the application uses fly ash floating beads as a key raw material, not only realizing the high-value utilization of industrial solid waste and reducing production costs, but also embodying significant environmental benefits, and opening up a new technical approach for the development of high-performance lightweight composites. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 Frontal photos of the floating bead anchoring three-phase composite material based on phase separation prepared in Examples 1-4, the pure thermosetting resin material prepared in Comparative Example 1, the thermoplastic resin modified thermosetting resin material prepared in Comparative Example 2, the floating bead modified thermosetting resin material prepared in Comparative Example 3 and the thermoplastic resin modified thermosetting resin material prepared in Comparative Example 4;

[0033] Figure 2 Longitudinal section photos, wherein (a) is the longitudinal section photo of the floating bead anchoring three-phase composite material based on phase separation prepared in Examples 1-4, and (b) is the longitudinal section photo of the pure thermosetting resin material prepared in Comparative Example 1, the thermoplastic resin modified thermosetting resin material prepared in Comparative Example 2, the floating bead modified thermosetting resin material prepared in Comparative Example 3 and the thermoplastic resin modified thermosetting resin material prepared in Comparative Example 4.

[0034] Figure 3 SEM of the phase separation based, bead anchored, three phase composite prepared in Example 1 before etching treatment;

[0035] Figure 4 SEM of the phase separation based, bead anchored, three phase composite prepared in Example 1 after etching treatment;

[0036] Figure 5 SEM of the phase separation based, bead anchored, three phase composite prepared in Example 2 after etching treatment;

[0037] Figure 6 SEM of the phase separation based, bead anchored, three phase composite prepared in Example 3 after etching treatment;

[0038] Figure 7 SEM of the phase separation based, bead anchored, three phase composite prepared in Example 4 after etching treatment;

[0039] Figure 8 SEM of the pure thermoset resin material prepared in Comparative Example 1 after etching treatment;

[0040] Figure 9 SEM of the thermoplastic resin modified thermoset resin material prepared in Comparative Example 2 after etching treatment;

[0041] Figure 10 SEM of the bead modified thermoset resin material prepared in Comparative Example 3 before etching treatment;

[0042] Figure 11 SEM of the thermoplastic resin modified thermoset resin material prepared in Comparative Example 4 after etching treatment;

[0043] Figure 12 Tensile strength of the phase separation based, bead anchored, three phase composites prepared in Examples 1-4, the pure thermoset resin material prepared in Comparative Example 1, the thermoplastic resin modified thermoset resin material prepared in Comparative Example 2, the bead modified thermoset resin material prepared in Comparative Example 3, and the thermoplastic resin modified thermoset resin material prepared in Comparative Example 4;

[0044] Figure 13 Impact strength of the phase separation based, bead anchored, three phase composites prepared in Examples 1-4, the pure thermoset resin material prepared in Comparative Example 1, the thermoplastic resin modified thermoset resin material prepared in Comparative Example 2, the bead modified thermoset resin material prepared in Comparative Example 3, and the thermoplastic resin modified thermoset resin material prepared in Comparative Example 4;

[0045] Figure 14Density of the phase separation based fly ash anchored three-phase composite material prepared in Examples 1-4, the pure thermosetting resin material prepared in Comparative Example 1, the thermoplastic resin modified thermosetting resin material prepared in Comparative Example 2, the fly ash modified thermosetting resin material prepared in Comparative Example 3 and the thermoplastic resin modified thermosetting resin material prepared in Comparative Example 4;

[0046] Figure 15 Heat transfer coefficient of the phase separation based fly ash anchored three-phase composite material prepared in Examples 1-4, the pure thermosetting resin material prepared in Comparative Example 1, the thermoplastic resin modified thermosetting resin material prepared in Comparative Example 2, the fly ash modified thermosetting resin material prepared in Comparative Example 3 and the thermoplastic resin modified thermosetting resin material prepared in Comparative Example 4. DETAILED DESCRIPTION

[0047] The technical solutions of the present application are further illustrated below in combination with specific examples.

[0048] The raw material information involved in the following examples is as follows:

[0049]

[0050] The molecular weight of the polyether sulfone is 47000 g / mol (determined by GPC), and the molecular weight of the polyphenyl sulfone is 48000 g / mol (determined by GPC).

[0051] The D50 of the fly ash floating bead is 43.85 μm. 50

[0052] The chemical composition of the fly ash floating bead is as follows:

[0053]

[0054] The implementation principle of the present application is as follows:

[0055] ​The preparation method of the present application is based on the mechanism of reaction-induced phase separation. The specific implementation principle is as follows: first, a prepolymer with continuously increasing molecular weight is formed through the step-by-step copolymerization reaction of thermosetting resin monomers and crosslinking agents. The compatibility of the prepolymer with thermoplastic resin gradually deteriorates with the increase of polymerization degree, and phase separation is induced when the system reaches the thermodynamic unstable critical point. This process conforms to the characteristic law of viscoelastic phase separation, that is, due to the dynamic asymmetry of the thermosetting resin component (prepolymer) and the thermoplastic resin component, a strong coupling effect between the phase separation kinetics and the rheological behavior of the system is generated. In the phase separation process, the surface-modified fly ash floating bead is confined in the microzone formed by the interface between the thermosetting resin-rich phase and the thermoplastic resin-rich phase, and the three-dimensional spatial barrier formed by the two-phase interface effectively inhibits the upward movement of the fly ash floating bead. With the continuous advancement of the curing reaction, the phase structure undergoes coarsening evolution and is finally permanently fixed through the gelation process of the system, forming a three-phase composite material with a specific micro-morphology. It needs to be specially pointed out that, since the macroscopic performance of the material is directly dependent on its microstructure, if the commercially available thermosetting resin is simply mixed with the system containing floating beads and thermoplastic resin, due to the lack of reaction-induced phase separation process, it is difficult to form a fine phase structure, and finally it is difficult to realize the synergistic improvement of lightweight, high toughness, high strength, excellent flame retardant performance and excellent thermal insulation performance of the material.

[0056] Examples 1-4

[0057] A preparation method of a floating bead anchoring three-phase composite material based on phase separation, comprising the following steps:

[0058] Step 1, mix the room temperature premix liquid and the 70℃ prepolymer system, stir at a speed of 500 rpm for 0.5 hours to uniform, to obtain a first mixed system, wherein,

[0059] The method for obtaining the premix liquid comprises: mixing the thermoplastic resin and the organic solvent at 30℃, stirring at a speed of 500 rpm for 1 hour to uniform, adding the fly ash floating bead, continuing to stir at a speed of 500 rpm for 0.5 hours to uniform, to obtain the premix liquid, the ratio of the mass fraction of the thermoplastic resin to the volume fraction of the organic solvent is 1:5, the unit of the mass fraction is g, and the unit of the volume fraction is mL. The thermoplastic resin is A; the organic solvent is a mixture of dichloromethane and trichloromethane, and the ratio of dichloromethane to trichloromethane is 1:1 in volume fraction;

[0060] The method for obtaining the prepolymer system comprises: preheating thermosetting resin monomers to 135℃, adding a crosslinking agent, stirring at 135℃ for 15 min to form a homogeneous transparent system, obtaining a prepolymer system containing a prepolymer (the prepolymer is formed by polymerization of the thermosetting resin monomers and the crosslinking agent), and cooling the prepolymer system to 70℃ before use (to prevent premature curing of the prepolymer), wherein the thermosetting resin monomers are bisphenol A diglycidyl ether (bisphenol A type epoxy resin monomers), and the crosslinking agent is 4,4'-diamino diphenyl sulfone (DDS, a polyamine crosslinking agent);

[0061] The mass ratio of fly ash floating beads, thermoplastic resin, thermosetting resin monomers and crosslinking agent is X,

[0062] Step 2, place the above first mixed system in a vacuum drying oven, and perform stepwise vacuum treatment (defoaming) to obtain a floating bead anchoring three-phase composite precursor based on phase separation, the stepwise vacuum treatment comprises: first vacuum treatment at 70℃ for 2 hours, then vacuum treatment at 140℃ for 0.5 hours under vacuum environment (vacuum degree is-0.09 MPa), pouring into a mold, and finally vacuum treatment at 140℃ for 0.5 hours;

[0063] Step 3, segmentally curing the floating bead anchoring three-phase composite precursor based on phase separation, cooling to room temperature, demolding, to obtain a floating bead anchoring three-phase composite material based on phase separation, wherein the segmental curing comprises: first curing at 140℃ for 4 hours, and then curing at 180℃ for 2 hours.

[0064] X and A are shown in Table 1.

[0065] Table 1

[0066]

[0067] Comparative Example 1

[0068] A method for preparing a pure thermosetting resin material, comprising the following steps:

[0069] Step 1, preheat thermosetting resin monomers to 135℃, add a crosslinking agent, stir at 135℃ for 15 min to form a homogeneous transparent system, obtain a prepolymer system containing a prepolymer, and cool to 70℃, wherein the mass ratio of the thermosetting resin monomers and the crosslinking agent is 75:25, the thermosetting resin monomers are bisphenol A diglycidyl ether (bisphenol A type epoxy resin monomers), and the crosslinking agent is 4,4'-diamino diphenyl sulfone (DDS);

[0070] Step 2, the prepolymer system at 70℃ is placed in a vacuum drying box for stepwise vacuum treatment to obtain a pure thermosetting resin material precursor, the stepwise vacuum treatment includes: first vacuum treatment at 70℃ for 2 hours and then vacuum treatment at 140℃ for 0.5 hours under vacuum environment (vacuum degree is -0.09 MPa), pouring into a mold, and finally vacuum treatment at 140℃ for 30 minutes;

[0071] Step 3, the pure thermosetting resin material precursor is subjected to segmented curing, cooled to room temperature, demolded, and a pure thermosetting resin material is obtained, wherein the segmented curing includes: first curing at 140℃ for 4 hours and then curing at 180℃ for 2 hours.

[0072] Comparative Example 2

[0073] A method for preparing a thermoplastic resin modified thermosetting resin material is basically the same as that of Example 2, the only difference is that fly ash floating beads are not added to the premixed solution of Comparative Example 2.

[0074] Comparative Example 3

[0075] A method for preparing a floating bead modified thermosetting resin material is basically the same as that of Example 2, the only difference is that thermoplastic resin is not added to the premixed solution of Comparative Example 3.

[0076] Comparative Example 4

[0077] A method for preparing a thermoplastic resin modified thermosetting resin material is basically the same as that of Example 4, the only difference is that fly ash floating beads are not added to the premixed solution of Comparative Example 4.

[0078] The front view photos and longitudinal section photos of the phase separation based floating bead anchored three-phase composite materials prepared in Examples 1-4, the pure thermosetting resin material prepared in Comparative Example 1, the thermoplastic resin modified thermosetting resin material prepared in Comparative Example 2, the floating bead modified thermosetting resin material prepared in Comparative Example 3 and the thermoplastic resin modified thermosetting resin material prepared in Comparative Example 4 are shown in Figure 1 and Figure 2 respectively. Figure 1 The front view photos of Example 1, Example 2, Example 3, Example 4, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 are shown from left to right in (a) of Figure 2 Figure 2 The longitudinal section photos of Comparative Examples 1-4 are shown from left to right in (b) of Figure 1 and Figure 2 As shown in (a) and (b) of Figure 2 ​As can be seen in Comparative Example 3, a large number of fly ash cenospheres were enriched on the top of the cenosphere-modified thermosetting resin material, forming a clearly defined aggregate layer. This is because the thermosetting resin cannot prevent the migration and aggregation of fly ash cenospheres.

[0079] To clearly characterize the microstructure of the materials, N,N-dimethylformamide (DMF) was used for selective etching (N,N-dimethylformamide has no solubility for fly ash cenospheres and thermosetting resins): the materials were immersed in N,N-dimethylformamide at 30°C for 30 min, thereby selectively dissolving and removing the thermoplastic resin-enriched phase. The materials were one of the following: the cenosphere-anchored three-phase composite materials based on phase separation prepared in Examples 1-4; the pure thermosetting resin material prepared in Comparative Example 1; and the thermoplastic resin-modified thermosetting resin materials prepared in Comparative Examples 2 and 4. The morphology of the materials was observed using a scanning electron microscope (Hitachi Regulus 8220, accelerating voltage 10 kV). The materials obtained according to Example 1... Figures 3~4 The SEM shown is an example. Figure 3 As shown, the three-phase composite material based on phase separation and anchoring, prepared in Example 1 before etching treatment, has a dense structure; as Figure 4 As shown, after etching, the thermoplastic resin enriched phase is dissolved, forming a large number of pores (dispersed phase). The distribution of the pores is as follows. Figure 4 As shown in regions A, B, C, and D, the fly ash cenospheres have a spherical structure, with the remaining continuous phase being thermosetting resin. This is based on the phase-separation-based cenosphere anchoring three-phase composite material obtained in Example 2. Figure 5 The SEM image shown; obtained according to Example 3, a three-phase composite material based on phase separation for anchoring microspheres. Figure 6 The SEM image shown; obtained according to Example 4, a three-phase composite material based on phase separation for anchoring microspheres. Figure 7 The SEM image shown; obtained from the pure thermosetting resin material of Comparative Example 1. Figure 8 The SEM image shown; the thermosetting resin material modified with thermoplastic resin according to Comparative Example 2 was obtained. Figure 9 The SEM image shown; the thermosetting resin material modified with thermoplastic resin according to Comparative Example 4 was obtained. Figure 11 The SEM shown is shown.

[0080] The fly ash-modified thermosetting resin material prepared in Comparative Example 3 did not involve thermoplastic resins, therefore selective etching was not performed. In Comparative Example 3, fly ash fly ash particles were enriched at the top of the fly ash-modified thermosetting resin material; therefore, the top of the fly ash-modified thermosetting resin material was taken for morphological observation, and the obtained SEM images are shown below. Figure 10 As shown.

[0081] Depend on Figure 4 and Figure 5It can be seen that in Examples 1-2, the thermoplastic resin (PES) rich phase mainly presents a continuous network distribution and is uniformly dispersed in the thermosetting resin rich phase. From the above, it can be seen that in the thermosetting resin rich phase of the three-phase composite material prepared in Examples 1-2, the thermoplastic resin (PES) rich phase is uniformly dispersed in the form of a continuous network structure. Figure 6 and Figure 7 It can be seen that in Examples 3-4, the thermoplastic resin (PPSU) rich phase is dispersed in the form of discrete droplets in the thermosetting resin rich phase. This is because during the reaction-induced phase separation process, the system undergoes typical viscoelastic phase separation behavior (Tanaka, H. (2000). Viscoelastic phase separation. Journal of Physics: Condensed Matter, 12, R207-R264.): as the crosslinking degree of the thermosetting resin increases, the system exhibits dynamic asymmetry, resulting in the formation of a continuous network structure of the thermoplastic resin rich phase at the early stage of phase separation; as the phase separation proceeds, the network structure undergoes a coarsening process and is eventually frozen during the segmented curing, forming a stable continuous network structure. Under the conditions of changing the type of thermoplastic resin, changing the segmented curing temperature and time, etc., the continuous network structure can further evolve into a discrete droplet structure. From the above, Figure 10 It can be seen that in Comparative Example 3, the fly ash floating beads are distributed in the fly ash floating bead modified thermosetting resin material at a much higher density than in Example 2, further confirming the conclusion that the fly ash floating beads are enriched on the top of the fly ash floating bead modified thermosetting resin material. In summary, in the phase separation-based floating bead anchoring three-phase composite materials of Examples 1-4, an interfacial surface is formed between the thermosetting resin rich phase and the thermoplastic resin rich phase, effectively blocking the migration and aggregation of the fly ash floating beads, and fundamentally solving the problem of the upward migration of the fly ash floating beads in Comparative Example 3.

[0082] According to the GB / T1040.2-2022 standard, the phase separation-based floating bead anchoring three-phase composite materials prepared in Examples 1-4, the pure thermosetting resin material prepared in Comparative Example 1, the thermoplastic resin modified thermosetting resin material prepared in Comparative Example 2, the fly ash floating bead modified thermosetting resin material prepared in Comparative Example 3, and the thermoplastic resin modified thermosetting resin material prepared in Comparative Example 4 were subjected to tensile testing (using a WDW-5C electronic universal testing machine). The test results are shown in Table 1. Figure 12 As shown in Table 1, among Examples 1-4 and Comparative Examples 1-4, the phase separation-based floating bead anchoring three-phase composite material prepared in Example 3 has the maximum tensile strength.

[0083] Impact strength tests were conducted on the three-phase composite materials based on phase separation anchoring prepared in Examples 1-4, the pure thermosetting resin material prepared in Comparative Example 1, the thermoplastic resin-modified thermosetting resin material prepared in Comparative Example 2, the cenosphere-modified thermosetting resin material prepared in Comparative Example 3, and the thermoplastic resin-modified thermosetting resin material prepared in Comparative Example 4, according to GB / T1843-2008 standard (using a WZY-240 cantilever beam impact testing machine). The test results are as follows: Figure 13 As shown ( Figure 13 The vertical axis is 0~15 kJ / m 2 (The paragraphs are compressed using " / / " and are actually continuous.) Compared with Comparative Example 1, the impact strength of Examples 1 to 4 increased by 53.8%–79.8%; the impact strength of Comparative Examples 2 to 4 was slightly improved compared with Comparative Example 1, but the improvement was limited.

[0084] The densities of the phase-separated cenosphere-anchored three-phase composite materials prepared in Examples 1-4, the pure thermosetting resin material prepared in Comparative Example 1, the thermoplastic resin-modified thermosetting resin material prepared in Comparative Example 2, the cenosphere-modified thermosetting resin material prepared in Comparative Example 3, and the thermoplastic resin-modified thermosetting resin material prepared in Comparative Example 4 are as follows: Figure 14 As shown ( Figure 14 The vertical axis is 0~1200kg / m 3 (The paragraphs are compressed using " / / " and are actually continuous). The densities of Examples 1-4 are all lower than those of Comparative Example 1, meeting the requirements for lightweighting. Among Examples 1-4 and Comparative Examples 1-4, the three-phase composite material based on phase separation and anchoring obtained in Example 4 has the lowest density.

[0085] The heat transfer coefficients of the phase-separated bead-anchored three-phase composite materials prepared in Examples 1-4, the pure thermosetting resin material prepared in Comparative Example 1, the thermoplastic resin-modified thermosetting resin material prepared in Comparative Example 2, the bead-modified thermosetting resin material prepared in Comparative Example 3, and the thermoplastic resin-modified thermosetting resin material prepared in Comparative Example 4 were tested using the steady-state heat flow method. The obtained heat transfer coefficients are as follows: Figure 15 As shown. The three-phase composite material based on phase separation and anchored by cenospheres prepared in Example 4 has the lowest heat transfer coefficient. The heat transfer coefficients of Examples 1-4 are reduced by 67.5%-78.2% compared to Comparative Example 1, exhibiting excellent thermal insulation performance.

[0086] The limiting oxygen index (LOI) was obtained by testing the sample according to GB / T 2406.2-2009; the first residual flame time t1 and the second residual flame time t2 were obtained by testing the sample according to GB / T 2408-2021, and the LOI, t1 and t2 are shown in Table 2, the sample is one of the phase separation based floating bead anchoring three-phase composite material prepared in Examples 1-4, the pure thermosetting resin material prepared in Comparative Example 1, the thermoplastic resin modified thermosetting resin material prepared in Comparative Example 2, the floating bead modified thermosetting resin material prepared in Comparative Example 3 and the thermoplastic resin modified thermosetting resin material prepared in Comparative Example 4. The sample was ignited for the first time to obtain the first residual flame time t1 (i.e. the time for which the sample continues to burn after the flame is removed), and the sample was ignited for the second time to obtain the second residual flame time t2; "-" indicates that the sample continues to burn and cannot be automatically extinguished after the flame is ignited; "0" indicates that the sample is not ignited. As can be seen from Table 2, the limiting oxygen index is increased from 23.5% of Comparative Example 1 to 27.0% of Example 2, the first residual flame time is shortened from 217s of Comparative Example 1 to 36s of Example 2, and Example 2 has no melt dripping phenomenon. Both Example 2 and Comparative Example 3 introduce fly ash floating beads, so the flame retardant performance of Example 2 is better due to the introduction of thermoplastic resin, that is, this excellent performance benefits from the synergistic effect of fly ash floating beads, thermoplastic resin and thermosetting resin.

[0087] Table 2

[0088]

[0089] According to the analysis of tensile strength, impact strength, heat transfer coefficient and flame retardant performance, although the tensile strength of Comparative Examples 2 and 4 is acceptable, the impact strength is very low; although the flame retardant performance and heat transfer coefficient of Comparative Example 3 are acceptable, the tensile strength and impact strength are extremely low, especially the tensile strength (the tensile strength of Comparative Example 3 is even lower than that of the pure thermosetting resin material of Comparative Example 1). The phase separation based floating bead anchoring three-phase composite material of the present application has good tensile strength, impact strength, heat insulation performance and flame retardant performance due to the synergistic effect of fly ash floating beads, thermoplastic resin and thermosetting resin, and especially the phase separation based floating bead anchoring three-phase composite material prepared in Example 2 achieves the optimal balance in comprehensive performance. The above results confirm the synergistic effect of fly ash floating beads and thermoplastic resin in improving the mechanical properties of thermosetting resin materials.

[0090] In summary, the present application successfully prepares a composite material with excellent mechanical properties, significant lightweight effect, excellent heat insulation performance and outstanding flame retardant properties by innovative phase structure design and effectively blocking the floating of floating beads by the two-phase interface of thermoplastic resin and thermosetting resin.

[0091] The above has made the exemplary description to the present application, should indicate that, in not departing from the core of the present application, any simple change, modification or other field technicians can not spend the equivalent replacement of creative labor falls into the protection scope of the present application.

Claims

1. A method for the preparation of a phase separation based, bead anchored, triphasic composite material, characterized by, The method comprises the following steps: Step 1, mixing a premix liquid and a prepolymer system to obtain a first mixed system, wherein the premix liquid comprises fly ash floating beads, a thermoplastic resin and an organic solvent, the prepolymer system comprises a prepolymer polymerized from a thermosetting resin monomer and a crosslinking agent, and the mass ratio of the fly ash floating beads, the thermoplastic resin, the thermosetting resin monomer and the crosslinking agent is (3-30):(10-20):(70-80):(20-30); Step 2, performing stepwise vacuum treatment on the first mixed system to obtain a phase separation-based floating bead anchoring three-phase composite material precursor; Step 3, performing segmented curing on the phase separation-based floating bead anchoring three-phase composite material precursor to obtain a phase separation-based floating bead anchoring three-phase composite material; The thermosetting resin monomer is an epoxy monomer, and the epoxy monomer is at least one of a bisphenol A type epoxy resin monomer, a bisphenol F type epoxy resin monomer, a hydrogenated bisphenol A type epoxy resin monomer and a phenolic epoxy resin monomer; The thermoplastic resin is a polysulfone resin, and the polysulfone resin is at least one of polyether sulfone and polyphenyl sulfone; The crosslinking agent is a polyamine crosslinking agent; The stepwise vacuum treatment comprises vacuum treatment at 60-80℃ for 1-3 hours, vacuum treatment at 130-150℃ for 0.25-6 hours, pouring into a mold, and finally vacuum treatment at 130-150℃ for 0.25-6 hours; The "three phases" in the floating bead anchoring three-phase composite material refer to fly ash floating beads, a thermosetting resin-rich phase and a thermoplastic resin-rich phase respectively, and the fly ash floating beads are anchored between the two-phase interface formed by the thermosetting resin-rich phase and the thermoplastic resin-rich phase.

2. The production method according to claim 1, characterized by, In step 1, the organic solvent is one or a mixture of several of dichloromethane, chloroform, N,N-dimethylformamide and tetrahydrofuran.

3. The preparation method according to claim 1, characterized in that, In step 1, the mass fraction of the thermoplastic resin and the volume fraction of the organic solvent are in a ratio of 1:(4-6), and the unit of the mass fraction is g and the unit of the volume fraction is mL.

4. The method of claim 1, wherein, The method for obtaining the prepolymer system comprises preheating the thermosetting resin monomer to 120-140℃, adding the crosslinking agent, stirring at 120-140℃ until a homogeneous transparent system is formed, and obtaining a prepolymer system containing a prepolymer.

5. The preparation method according to claim 1, characterized in that, In step 3, the segmented curing comprises first curing at 135-145℃ for 3-5 hours, and then curing at 175-185℃ for 1-3 hours.

6. The phase separation-based floating bead anchoring three-phase composite material obtained by the preparation method of any one of claims 1-5.

7. Application of the phase separation-based floating bead anchoring three-phase composite material of claim 6 in improving the tensile strength, impact strength, heat insulation performance and / or flame retardant performance of a material.

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