A composite material based on interface-enhanced glass hollow microspheres and a preparation method thereof

Abstract

The application discloses a composite material based on interface-enhanced glass hollow microspheres and a preparation method thereof, wherein the composite material comprises a resin matrix and composite glass hollow microspheres doped in the resin matrix, and the density of the composite material is 0.2-1.0 g / cm ‑3 . The composite glass hollow microspheres are composed of glass hollow microspheres and carbon nanoparticles modified on the surfaces of the glass hollow microspheres. In the composite material, the glass hollow microspheres modified with the carbon nanoparticles optimize the hollow surface structure of the microspheres, improve the wettability with the polymer resin matrix, repair the defects on the surfaces of the microspheres, and enhance the strength of the microspheres. In addition, the carbon nanoparticles in the composite glass hollow microspheres play a reinforcing role at the interfaces of the microspheres. The above factors together make the composite material have more excellent mechanical properties and stability.

Description

Technical Field

[0001] This invention relates to the field of composite materials technology. More specifically, it relates to a composite material based on interface-reinforced glass hollow microspheres and its preparation method. Background Technology

[0002] Lightweighting is a significant advantage of polymer composites. Hollow microsphere composites (also known as composite foam materials) are a type of closed-cell foam material obtained by uniformly dispersing hollow microsphere fillers in a matrix resin. This material combines lightweight and high strength, making it an effective solution for lightweighting composite materials. Through formulation design and process optimization, a series of composite materials with different densities and strengths can be obtained, and they are widely used in aerospace and deep-sea applications. To reduce the overall density, the volumetric filling amount of hollow microspheres in these composites is relatively large, reaching over 60%. However, this increased filling amount introduces a large number of interfaces into the composite system. Interfaces are crucial to the strength of composite materials; the interface state not only affects the immediate performance of the composite material but also its long-term stability.

[0003] Hollow silicate glass microspheres are one of the most commonly used hollow fillers in composite foams, offering advantages such as low cost, high compressive strength, and ease of dispersion and filling. During preparation, alkali metal and alkaline earth metal components are added to lower the melting point of silica, facilitating molding. However, this not only weakens the wettability between the microspheres and resin, but more importantly, these alkali metal and alkaline earth metal components are prone to leaching in aqueous environments, thereby damaging the interface between the microspheres and the resin matrix and leading to a decrease in the long-term stability of the composite material. Chinese invention patent application No. 202010389529.2 describes a surface acid immersion treatment of hollow glass microspheres to remove surface alkali, followed by heat treatment. The resulting composite material, obtained by combining these microspheres with resin, improves the interface and enhances the stability of mechanical properties. However, the immediate strength improvement of the composite material obtained by this method is not significant. To improve the immediate strength of the composite material, third-phase reinforcement of the resin matrix is ​​an effective method. However, the cavity walls inside the hollow microsphere composite material are weak points in mechanical properties, and the overall reinforcement of the resin matrix by the third-phase filler cannot specifically improve the interface region. In addition, third-phase fillers are usually small in size, which makes it difficult to disperse them evenly; moreover, the density of fillers is usually much higher than that of conventional resins, and the overall reinforcement of the resin matrix will inevitably require a higher amount of filler to increase the density of the composite material. Summary of the Invention

[0004] Based on the above facts, the purpose of this invention is to provide a composite material based on interface-reinforced glass hollow microspheres and its preparation method, so as to at least solve the problem that the immediate strength improvement of lightweight composite materials based on glass hollow microspheres is not obvious.

[0005] On one hand, the present invention provides a composite material based on interface-reinforced hollow glass microspheres, wherein the composite material comprises a resin matrix and composite hollow glass microspheres doped in the resin matrix, and the density of the composite material is 0.2-1.0 g / cm³. -3 ;

[0006] The composite glass hollow microspheres are composed of glass hollow microspheres and carbon nanoparticles modified on the surface of the glass hollow microspheres.

[0007] In the technical solution of this invention, there are no other requirements for the selection of glass hollow microspheres. They can be conventional commercially available glass hollow microspheres or glass hollow microspheres prepared by methods published in existing literature (for example, they can be prepared by referring to the method disclosed in Chinese Invention Patent Application No. 201210056295.5).

[0008] Furthermore, the hollow glass microspheres contain alkali metals and / or alkaline earth metals.

[0009] Furthermore, the volume content of the composite glass hollow microspheres in the composite material is 0.01-96%, preferably 40-70%.

[0010] Furthermore, the composite glass hollow microspheres have a particle size of 10-120 μm and a true density of 0.1-0.6 g / cm³. -3 The content of carbon nanoparticles is 0.01-1 wt%.

[0011] In the technical solution of this invention, the resin matrix is ​​a commonly used resin matrix for preparing composite materials with rigid supporting properties.

[0012] Furthermore, the resin matrix is ​​selected from resins that are in a flowable state before curing or that are flowable after being diluted with solvent.

[0013] Furthermore, the resin matrix is ​​selected from one of epoxy resin, unsaturated polyester resin, phenolic resin, polyolefin, silicone resin, polyurethane resin or polystyrene.

[0014] Furthermore, the composite glass hollow microspheres are prepared by a method comprising the following steps:

[0015] The composite glass hollow microspheres were obtained by sequentially subjecting the glass hollow microspheres to acid leaching, adsorption of small molecule carbon sources, and carbonization treatment.

[0016] The acid leaching process described above is a dealkalization treatment of the glass hollow microspheres. Specifically, the acid leaching process may include: mixing the glass hollow microspheres with 1 mol / L hydrochloric acid at a volume ratio of 1:1.5 under mechanical stirring for 60 minutes, followed by filtration, drying, and sieving to remove agglomerated particles.

[0017] Furthermore, the method for adsorbing small molecule carbon sources is as follows: the acid-impregnated glass hollow microspheres are immersed in an aqueous solution of small molecule carbon sources, and then filtered, dried, and sieved to remove agglomerated particles.

[0018] Furthermore, the concentration of the aqueous solution of the small molecule carbon source is 0.01-1 g / mL;

[0019] The small molecule carbon source is a small molecule organic carbon source, selected from one or more of starch, sucrose, maltose, glucose or polyvinyl alcohol.

[0020] Furthermore, during the impregnation process, the volume ratio of the glass hollow microspheres to the aqueous solution of the small molecule carbon source is 1:1 to 1:10. This process is preferably carried out under stirring conditions, and the stirring time is preferably 5-12 hours.

[0021] Furthermore, the drying temperature is 40-80℃, and the time is 2-24 hours. The drying is preferably carried out in a drying oven.

[0022] Furthermore, the carbonization process is carried out in a nitrogen atmosphere at a temperature of 400-700℃ for 1-6 hours. More specifically, the carbonization process also includes flotation removal of broken microspheres after carbonization, followed by drying and sieving.

[0023] The preferred method for flotation is to mix the carbonized microspheres with ethanol or water at a volume ratio of 1:1 to 1:10, allow them to stand and separate into layers, then take the upper floating material, filter, and dry.

[0024] Furthermore, the raw materials of the composite material also include additives. Exemplary additives include, but are not limited to, one or more selected from curing agents, accelerators, coupling agents, and diluents. Those skilled in the art can select the choice and dosage of each additive according to the actual situation. Taking epoxy resin as an example, suitable curing agents include, but are not limited to, methylhexahydrophthalic anhydride; suitable accelerators include, but are not limited to, N,N-dimethylbenzylamine; and suitable diluents include, but are not limited to, fatty alcohol diglycidyl ether (V22).

[0025] In another aspect, the present invention provides a method for preparing the composite material as described above, comprising the following steps:

[0026] Mix the raw material components containing the resin matrix thoroughly;

[0027] Composite glass hollow microspheres were added under stirring conditions, mixed well, and degassed.

[0028] The material is poured into the mold and degassed by alternating vacuum vibration;

[0029] The material is cured to obtain the composite material.

[0030] The beneficial effects of this invention are as follows:

[0031] In the composite material provided by this invention, the presence of glass hollow microspheres modified with carbon nanoparticles optimizes the hollow surface structure of the microspheres, improves the wettability with the polymer resin matrix, repairs defects on the surface of the microspheres, and enhances the strength of the microspheres. In addition, the carbon nanoparticles in the composite glass hollow microspheres play a reinforcing role at the microsphere interface. All of the above factors together make the composite material have better mechanical properties and stability.

[0032] The method for preparing composite materials provided by this invention allows for the direct control of processing time, carbon source type, carbon source solution concentration, and carbonization treatment to obtain composite glass hollow microspheres with different surface structures and carbon contents. This invention is applicable to different types of glass hollow microspheres; by adjusting the microsphere type and volume fraction, a series of lightweight and high-strength composite materials can be obtained. Compared to blank glass microsphere composite materials, the modified glass hollow microspheres in this invention not only significantly improve the immediate mechanical properties of the composite material, but also enhance the long-term stability of the composite material in an aqueous environment through improved interface and carbon material stability. Attached Figure Description

[0033] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0034] Figure 1 The diagram shows the surface modification treatment of glass hollow microspheres and the preparation of composite materials in Example 1.

[0035] Figure 2 SEM images of blank glass hollow microspheres, acid-impregnated glass hollow microspheres, directly modified carbon glass hollow microspheres, and acid-impregnated + modified carbon glass hollow microspheres are shown in Example 1.

[0036] Figure 3 The contact angle of the hollow microspheres in the blank glass in Example 1 is shown.

[0037] Figure 4 The contact angle of the acid-impregnated glass hollow microspheres in Example 1 is shown.

[0038] Figure 5 The contact angle of the acid-impregnated and modified carbon glass hollow microspheres in Example 1 is shown.

[0039] Figure 6 Photographs show composite materials prepared using blank glass hollow microspheres (1), acid-impregnated glass hollow microspheres (2), directly modified carbon glass hollow microspheres, or acid-impregnated + modified carbon glass hollow microspheres (3) from Example 1.

[0040] Figure 7The diagrams show the instantaneous compression strength and the compressive strength in an aqueous environment of the composite materials formed by blank glass hollow microspheres, acid-impregnated glass hollow microspheres, directly modified carbon glass hollow microspheres, and acid-impregnated + modified carbon glass hollow microspheres in Example 1. Detailed Implementation

[0041] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further explains the invention. Similar components in the drawings are indicated by the same reference numerals. Those skilled in the art should understand that the specific description below is illustrative rather than restrictive and should not be construed as limiting the scope of protection of the present invention.

[0042] Example 1

[0043] In this embodiment, the method of the present invention is used to modify self-made hollow glass microspheres, and the treated microspheres are then combined with a resin matrix to form a composite material.

[0044] The preparation of the self-made hollow glass microspheres in this invention is achieved according to application number 201210056295.5, "A soft chemical preparation method for hollow glass microspheres and the prepared hollow glass microspheres and their applications." In this embodiment, the density of the hollow glass microspheres is 0.30 g / cm³. 3 The model number is T30, and the particle size is 20-80μm.

[0045] The modification of microspheres in this embodiment first involves acid leaching to remove alkali. Specifically, the microspheres are mixed with 1 mol / L hydrochloric acid at a volume ratio of 1:1.5 and mechanically stirred for 60 min. Then, the mixture is filtered, dried, and sieved to remove agglomerated particles. Next, adsorption treatment is performed. Specifically, water-soluble starch is used as the carbon source. 1 g of starch is placed in 40 mL of water and mechanically stirred until the solution is clear and transparent (the concentration of water-soluble starch is 0.025 g / mL). The volume ratio of microspheres to carbon source solution is controlled at 1:6, and mechanical stirring is performed for 5 h. The mixture is then filtered, dried in a 60℃ drying oven for 2 h, and sieved to remove agglomerated particles. Finally, carbonization is performed. Specifically, the adsorption-treated microspheres are placed in a tube furnace and carbonized at 600℃ for 3 h in a N2 atmosphere. Finally, flotation was used to remove broken microspheres. Specifically, a 1:1 volume ratio of water to ethanol was used as the flotation solution, and the ratio of microspheres to the ethanol-water solution was controlled at 1:3. The mixture was thoroughly mixed, allowed to stand and separate into layers to remove precipitates, and this process was repeated three times. The upper floating layer was collected, dried, and sieved to obtain a modified glass hollow microsphere with a small amount of carbon modified to maintain its density (i.e., the composite glass hollow microsphere). Meanwhile, blank glass microspheres without acid leaching were directly modified with carbon as a comparison, and the specific carbon modification process was the same as described above.

[0046] The surface morphologies of blank microspheres, acid-treated microspheres, directly modified carbon microspheres, and acid-treated + modified carbon microspheres are as follows: Figure 2As shown, the surface morphology showed no significant change. However, carbon-sulfur analysis revealed that directly modified carbon microspheres contained 0.18 wt% carbon, while acid-treated + modified carbon microspheres contained 0.15 wt% carbon, with almost no effect on density, as shown in Table 1. The presence of a small amount of carbon, on the one hand, enhances hydrophobicity, as shown in Table 1. Figure 3-5 As shown in Table 1, this improved the wettability of the microspheres with the resin. On the other hand, as shown in Table 1, the precipitation of alkali metal ions after acid leaching increased defects in the microsphere shell, leading to a decrease in microsphere strength. The modified carbon repaired these defects, thereby improving the strength of the microspheres themselves. It is worth noting that the carbon material itself has a reinforcing effect.

[0047] Finally, the composite materials were prepared. Specifically, epoxy resin E51, TDE85, methylhexahydrophthalic anhydride, N,N-dimethylbenzylamine, and KH560 were mixed uniformly in a mass ratio of 100:100:228.5:4.3:4.3. Blank microspheres, acid-impregnated microspheres, directly coated carbon microspheres, and acid-impregnated + modified carbon microspheres were then added, respectively. The proportion of glass hollow microspheres added was 58% of the volume of the composite material. The mixtures were then heated and cured at 80℃, 120℃, and 160℃ for 2 hours, 2 hours, and 4 hours, respectively. After cooling, the corresponding composite materials were obtained, and the results are as follows. Figure 6 As shown, the carbon material exhibits reduced agglomeration with uniform dispersion of microspheres. The resulting composite materials were then subjected to a 100°C water environment treatment for one day, and their uniaxial compressive properties were measured after 12 hours. The results are as follows. Figure 7 As shown, the instantaneous compressive strength of the composite material formed by acid-impregnated microspheres increased by 3.4% compared to the blank microspheres, a negligible improvement. However, the instantaneous compressive strength of the composite foam formed by directly modified carbon microspheres and acid-impregnated + modified carbon microspheres increased by 10.9% and 11.8% respectively, showing significant improvements. This is attributed to the improvement of the interface by the small amount of modified carbon, the increased strength of the microspheres, and their own reinforcing effect. Meanwhile, after being exposed to water at 100℃, the strength of the composite foam formed by the blank microspheres decreased by 22.3%, the composite foam formed by acid-impregnated microspheres decreased by 5.3%, the composite material formed by directly coated carbon microspheres decreased by 11.3%, and the composite material formed by acid-impregnated + modified carbon microspheres decreased by 7.3%. The strength reduction rate of the composite material formed by acid-impregnated + modified carbon microspheres was slightly greater than that of the acid-impregnated microsphere composite foam, differing by only 2%. This may be due to the introduction of a new interface by a small amount of modified carbon, causing a slight performance degradation. Compared to the composite material formed by the blank microspheres, its long-term stability was significantly improved, which is attributed to the removal of alkali and the improvement of the interface. The strength reduction of the composite material formed by direct modification of carbon microspheres is greater than that of the composite material formed by acid leaching + carbon microsphere coating, which may be due to the effect of ion precipitation.

[0048] Table 1. Basic information of the microspheres before and after treatment.

[0049] Blank microspheres 0.302 92.45 Acid-etched microspheres 0.304 90.17 Direct modification of carbon microspheres 0.307 96.59 Acid leaching + modified carbon microspheres 0.304 95.81

[0050] Note: The volume survival rate test method under 10MPa pressure in Table 1 refers to GJB 3594-99 "Test Method for Hollow Microspheres".

[0051] The preparation process of the glass hollow microsphere composite material in Examples 2-13 is similar to that in Example 1. The specific conditions and performance parameters are shown in Tables 2-4.

[0052] Table 2. Preparation conditions and density of glass hollow microsphere composite materials in Examples 2-13

[0053]

[0054] Note: The preparation of the T20 and T38 hollow glass microspheres mentioned above was carried out in accordance with application number 201210056295.5, "A soft chemical preparation method for hollow glass microspheres and the prepared hollow glass microspheres and their applications". The densities of the T20 and T38 hollow glass microspheres are 0.20 g / cm³, respectively. 3 and 0.38g / cm 3 .

[0055] Table 3: Instantaneous strength of glass hollow microsphere composite materials in Examples 1-13

[0056]

[0057] Table 4: Strength of glass hollow microsphere composite materials after hydrothermal treatment in Examples 1-13

[0058]

[0059] Hydrothermal aging treatment: The composite material test standard block was placed in a 100℃ water environment for 1 day.

[0060] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A composite material based on interface-reinforced glass hollow microspheres, characterized in that, The composite material consists of a resin matrix and composite hollow glass microspheres doped within the resin matrix, and the density of the composite material is 0.2-1.0 g / cm³. 3 ; The composite glass hollow microspheres are composed of glass hollow microspheres and carbon nanoparticles modified on the surface of the glass hollow microspheres. The preparation of the composite glass hollow microspheres consists of the following steps: The composite glass hollow microspheres were obtained by sequentially subjecting the glass hollow microspheres to acid leaching, adsorption of small molecule carbon sources, and carbonization treatment. The acid leaching consists of the following steps: glass hollow microspheres and 1 mol / L hydrochloric acid at a volume ratio of 1:1.5 are kept under mechanical stirring for 60 min, followed by filtration, drying, and sieving to remove agglomerated particles; The method for adsorbing small molecule carbon sources consists of the following steps: immersing acid-soaked glass hollow microspheres in an aqueous solution of small molecule carbon sources, followed by filtration, drying, and sieving to remove agglomerated particles. The carbonization process is carried out in a nitrogen atmosphere at a temperature of 400-700℃ for 1-6 hours. The volume content of the composite glass hollow microspheres in the composite material is 40-70%; The resin matrix is ​​selected from one of epoxy resin, unsaturated polyester resin, silicone resin or polyurethane resin; The small molecule carbon source is a small molecule organic carbon source, selected from one or more of starch, sucrose, maltose, glucose or polyvinyl alcohol.

2. The composite material according to claim 1, characterized in that, The composite glass hollow microspheres have a particle size of 10-120 μm and a true density of 0.1-0.6 g / cm³. 3 The content of carbon nanoparticles is 0.01-1 wt%.

3. The composite material according to claim 1, characterized in that, The concentration of the aqueous solution of the small molecule carbon source is 0.01-1 g / mL.

4. The method for preparing the composite material according to any one of claims 1-3, characterized in that, Includes the following steps: Mix the raw material components containing the resin matrix thoroughly; Composite glass hollow microspheres were added under stirring conditions, mixed well, and degassed. The material is poured into the mold and degassed by alternating vacuum vibration; The material is cured to obtain the composite material.

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