In-situ grown inorganic lamellar particle reinforced toughened polyurethane composite material and preparation method thereof

Abstract

The invention discloses an in-situ inorganic lamellar particle reinforced toughened polyurethane composite material and a preparation method thereof, and relates to the technical field of multifunctional composite materials. The method comprises the following steps: (1) dissolving tannic acid in deionized water, freezing, and obtaining ice cube A; (2) dissolving calcium chloride in deionized water, freezing, and obtaining ice cube B; (3) dissolving disodium hydrogen phosphate dodecahydrate and sodium dihydrogen phosphate in deionized water, and obtaining solution C; (4) blending waterborne polyurethane, solution C, and ice cube B, stirring and melting, and then adding ice cube A, stirring and melting, vacuum filtering, and drying. The invention also discloses an in-situ inorganic lamellar particle reinforced toughened polyurethane composite material prepared by the above method. The composite material has high toughness, high strength, high elongation at break, and a wide damping temperature range, and solves the problems of poor mechanical properties of polyurethane composite materials and complex and difficult operation of in-situ crystallization methods in polyurethane matrix.

Description

Technical Field

[0001] The invention relates to the technical field of multifunctional composite materials, and in particular to an in-situ grown inorganic lamellar particle reinforced and toughened polyurethane composite material and a preparation method thereof. Background Art

[0002] It is well known that the mechanical properties of polymer / inorganic filler composites are mainly affected by the dispersion state of the filler and the interfacial interaction between the inorganic filler and the polymer matrix. It has been demonstrated that polymer composites can be reinforced by adding various types of inorganic fillers, but few studies have focused on both the reinforcement and toughening properties of elastomeric composites. Composites composed of two heterogeneous structural units with different properties are the most common approach to design new efficient and functional elastomeric composites. The purpose of strengthening and toughening elastomeric composites is achieved by improving the uniformity of inorganic fillers in the matrix and enhancing the connection and interfacial adhesion between the inorganic filler and the polymer matrix.

[0003] At present, the methods of using inorganic particles to strengthen and toughen elastomer composites are generally: directly blending inorganic particles with polymers or modifying inorganic particles before blending with the matrix. These two methods are inevitably restricted by the dispersibility of inorganic particles and their surface inertness, which limits their degree of strengthening and toughening of elastomer composites. Another uncommon method is to grow inorganic particles in situ in the matrix to achieve the effect of strengthening and toughening. However, this method is limited by factors such as complex operation and difficulty in in-situ particle growth. Therefore, if a method for in-situ growth of inorganic particles that is simple to operate and easy to grow particles can be designed, it will promote a new era of preparation of in-situ grown particle-reinforced and toughened composites.

[0004] In summary, the art urgently needs to develop a simple method for in-situ growth of inorganic lamellar particles to reinforce and toughen polyurethane composites, so as to fundamentally solve the problems caused by the interfacial inertia and uneven distribution of inorganic particles in polyurethane composites prepared by traditional blending methods, as well as the problem of complex and difficult operation of traditional methods of in-situ growth of particles in polymer matrices. Summary of the invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide an in-situ grown inorganic lamellar particle reinforced and toughened polyurethane composite material and a preparation method thereof. The composite material has high toughness, high strength, high elongation at break and a wide damping temperature range, and solves the problems of poor reinforcement and toughening effect caused by the interface inertia and uneven distribution of inorganic particles in the polyurethane composite material prepared by the traditional blending method and the complex and difficult operation of the traditional method of in-situ growth of particles in a polymer matrix.

[0006] The present invention solves the above technical problems by providing a method for preparing an in-situ grown inorganic lamellar particle reinforced and toughened polyurethane composite material, comprising the following steps:

[0007] (1) dissolving tannic acid in deionized water, and then freezing the water to obtain ice cube A;

[0008] (2) dissolving calcium chloride in deionized water, and then freezing the water to obtain ice cube B;

[0009] (3) dissolving disodium hydrogen phosphate dodecahydrate and sodium dihydrogen phosphate in deionized water to obtain solution C;

[0010] (4) blending the aqueous polyurethane, the solution C obtained in step (3) and the ice cube B obtained in step (2), stirring until the ice cubes are completely melted, then adding the ice cube A obtained in step (1), stirring until the ice cubes are completely melted, vacuum filtering and drying to obtain an in-situ grown inorganic lamellar particle reinforced and toughened polyurethane composite material.

[0011] The beneficial effect of the technical solution of the present invention is as follows: the method of the present invention rapidly freezes the calcium chloride solution under liquid nitrogen into cold quenched ice, and then rapidly melts it in a mixed solution of disodium hydrogen phosphate dodecahydrate, sodium dihydrogen phosphate and polyurethane, and the cold quenched ice forms supercooled water at the interface with water in the polyurethane mixed solution when melting, and the calcium ions exposed to the supercooled water are restricted to crystallize with hydrogen phosphate and dihydrogen phosphate in the polyurethane mixed solution to form phosphate, thereby obtaining a phosphate polyurethane composite material crystallized in situ on the polyurethane. Then, a rapidly frozen tannic acid solution is added to the composite material to induce crosslinking under supercooled water conditions, thereby preparing a composite material with high mechanical properties.

[0012] The method of the present invention is to use water to be rapidly frozen (cold quenched ice) in liquid nitrogen to crystallize and then rapidly melt in a solution to obtain supercooled water, and to generate flaky phosphate crystals in the supercooled water, thereby increasing the mechanical properties of the composite material. The preparation method of supercooled water-assisted in-situ crystallization at the phase interface can effectively prepare hydroxyapatite crystals.

[0013] The inventors started from the perspective of supercooled water-induced in-situ crystallization of the interface and the cross-linking of tannic acid and polyurethane, and after extensive research, found that the above-mentioned preparation method can introduce a large number of dynamic coordination bonds and hydrogen bonds into the polyurethane composite material, while improving the interfacial bonding between hydroxyapatite and the polymer matrix.

[0014] Furthermore, in step (1), the mass volume ratio of tannic acid to deionized water is 3-7 g:100 mL.

[0015] Furthermore, in step (2), the mass volume ratio of calcium chloride to deionized water is 3-7 g:100 mL.

[0016] Furthermore, in steps (1) and (2), the product is placed in liquid nitrogen for freezing without pre-freezing treatment.

[0017] Furthermore, in step (3), the mass volume ratio of disodium hydrogen phosphate dodecahydrate, sodium dihydrogen phosphate and deionized water is 1-4 g: 0.5-3 g: 100 mL.

[0018] Furthermore, in step (3), disodium hydrogen phosphate dodecahydrate can be replaced by dipotassium hydrogen phosphate with crystal water, and sodium dihydrogen phosphate can be replaced by potassium dihydrogen phosphate. Furthermore, in this method, tannic acid, calcium chloride and phosphate must be completely dissolved.

[0019] Furthermore, in step (4), the solid content of the waterborne polyurethane is 20%-70%.

[0020] Furthermore, in step (4), the mass volume ratio of the aqueous polyurethane to the solution C is 1-3 g:35-75 mL; the volumes of the solution C, the ice cube B and the ice cube A are the same in terms of liquid volume.

[0021] Furthermore, in step (4), a PP filter membrane with a pore size of 0.22 μm is used for suction filtration.

[0022] Furthermore, in step (4), drying is performed at a temperature of 40-80°C.

[0023] The present invention also provides an in-situ grown inorganic lamellar particle reinforced toughened polyurethane composite material prepared by the preparation method of the in-situ grown inorganic lamellar particle reinforced toughened polyurethane composite material.

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

[0025] 1. The in-situ growth inorganic lamellar particle reinforced toughened polyurethane composite material prepared by the method of supercooled water assisted in-situ crystallization at the phase interface has high toughness (467MJ·m -3 ), high strength (30.3MPa), high elongation at break (2411%) and wide damping temperature range (>120℃; temperature range of tanδ>0.3), and the inorganic particles in the composite material are in a flake shape. This work provides a new material design concept for high-performance polyurethane composites.

[0026] 2. The method of the present invention improves the bonding effect between hydroxyapatite and the polyurethane matrix and the density of dynamic bonds in the composite material through supercooled water-assisted in-situ crystallization at the phase interface, thereby solving the problems of agglomeration of tannic acid in the polymer substrate, poor mechanical properties caused by direct introduction of hydroxyapatite into the polymer matrix, and complex and difficult operation of the in-situ crystallization method in the matrix.

[0027] 3. The method of the present invention has the advantages of simple process, strong controllability, good stability, mild reaction conditions and low cost, and the overall process is conducive to large-scale industrial processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a graph showing the mechanical properties test results of the in-situ grown inorganic lamellar particles reinforced and toughened polyurethane composite material according to Example 1;

[0029] Figure 2 This is a graph showing the damping performance test results of the in-situ grown inorganic lamellar particles reinforced and toughened polyurethane composite material according to Example 1;

[0030] Figure 3 This is a graph showing the XRD test results of the in-situ grown inorganic lamellar particles reinforced and toughened polyurethane composite material according to Example 1;

[0031] Figure 4 This is a scanning electron microscope test result of the in-situ grown inorganic lamellar particles reinforced and toughened polyurethane composite material in Example 1. DETAILED DESCRIPTION

[0032] The principles and features of the present invention are described below, and the examples are only used to explain the present invention and are not used to limit the scope of the present invention. If no specific conditions are specified in the embodiments, they are carried out according to normal conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0033] Example 1

[0034] An in-situ grown inorganic lamellar particle reinforced and toughened polyurethane composite material, the preparation method of which comprises the following steps:

[0035] (1) Dissolve 5 g of tannic acid in 100 mL of deionized water, and then freeze the mixture in liquid nitrogen to obtain ice cube A;

[0036] (2) Dissolve 5 g of calcium chloride in 100 mL of deionized water, and then freeze the mixture in liquid nitrogen to obtain ice block B;

[0037] (3) dissolving 3 g of disodium hydrogen phosphate dodecahydrate and 1 g of sodium dihydrogen phosphate in 100 mL of deionized water to obtain solution C;

[0038] (4) 2 g of aqueous polyurethane with a solid content of 60%, 40 mL of solution C obtained in step (3) and 40 mL of ice cube B obtained in step (2) are mixed and stirred until the ice cubes are completely melted. Then 40 mL of ice cube A obtained in step (1) is added and stirred until the ice cubes are completely melted. The mixture is vacuum filtered and dried at 70° C. to obtain an in-situ grown inorganic lamellar particle reinforced and toughened polyurethane composite material.

[0039] Example 2

[0040] An in-situ grown inorganic lamellar particle reinforced and toughened polyurethane composite material, the preparation method of which comprises the following steps:

[0041] (1) Dissolve 3 g of tannic acid in 100 mL of deionized water, and then freeze the mixture in liquid nitrogen to obtain ice cube A;

[0042] (2) Dissolve 3 g of calcium chloride in 100 mL of deionized water, and then freeze the mixture in liquid nitrogen to obtain ice block B;

[0043] (3) dissolving 1 g of dipotassium hydrogen phosphate trihydrate and 0.5 g of potassium dihydrogen phosphate in 100 mL of deionized water to obtain solution C;

[0044] (4) 1 g of aqueous polyurethane with a solid content of 20%, 35 mL of solution C obtained in step (3) and 35 mL of ice cube B obtained in step (2) are mixed and stirred until the ice cubes are completely melted. Then 35 mL of ice cube A obtained in step (1) is added and stirred until the ice cubes are completely melted. The mixture is vacuum filtered and dried at 40° C. to obtain an in-situ grown inorganic lamellar particle reinforced and toughened polyurethane composite material.

[0045] Example 3

[0046] An in-situ grown inorganic lamellar particle reinforced and toughened polyurethane composite material, the preparation method of which comprises the following steps:

[0047] (1) Dissolve 7 g of tannic acid in 100 mL of deionized water, and then freeze the mixture in liquid nitrogen to obtain ice cube A;

[0048] (2) Dissolve 7 g of calcium chloride in 100 mL of deionized water, and then freeze the mixture in liquid nitrogen to obtain ice block B;

[0049] (3) dissolving 4 g of disodium hydrogen phosphate dodecahydrate and 3 g of sodium dihydrogen phosphate in 100 mL of deionized water to obtain solution C;

[0050] (4) 3 g of aqueous polyurethane with a solid content of 70%, 75 mL of solution C obtained in step (3) and 75 mL of ice cube B obtained in step (2) are mixed and stirred until the ice cubes are completely melted. Then 75 mL of ice cube A obtained in step (1) is added and stirred until the ice cubes are completely melted. The mixture is vacuum filtered and dried at 80° C. to obtain an in-situ grown inorganic lamellar particle reinforced and toughened polyurethane composite material.

[0051] Comparative Example 1

[0052] A composite material of polyurethane and hydroxyapatite is prepared by in-situ polymerization of β-cyclodextrin with hexamethylene diisocyanate and hydroxyapatite according to Du et al. (Du Jingjing, Gan Shuchun, Bian Qihao, Fu Duhan, Wei Yan, Wang Kaiqun, Lin Qiaoxia, Chen Weiyi and Huang Di, Preparation and characterization of porous hydroxyapatite / β-cyclodextrinbased polyurethane composite scaffolds for bone tissue engineering, Journal of Biomaterials Applications 33(3)(2018)402-409). Due to the limitations of their method, the obtained composite material has poor mechanical properties (stress and strain are 12.95 MPa and 65%, respectively) and has no damping performance.

[0053] Test Example 1: Mechanical Properties

[0054] The in-situ grown inorganic lamellar particles reinforced and toughened polyurethane composite material of Example 1 was tested, and a pure polyurethane comparative sample was prepared at the same time. The mechanical properties of the samples were tested by a tensile testing machine. The experimental results are as follows Figure 1 shown.

[0055] Depend on Figure 1 It can be seen that the in-situ grown inorganic lamellar particle reinforced toughened polyurethane composite material of Example 1 exhibits higher stress, strain and toughness, with the highest toughness reaching 467 MJ·m -3 , the tensile strength can reach 30.3MPa, the elongation at break can reach 2411%, and it has extremely high mechanical properties. The results show that the preparation of hydroxyapatite polyurethane composites by supercooled water-assisted in-situ crystallization at the phase interface can significantly improve the mechanical properties of the material.

[0056] Test Example 2: Damping Performance

[0057] The in-situ grown inorganic lamellar particles reinforced toughened polyurethane composite material of Example 1 was tested, and a pure polyurethane comparison sample was prepared at the same time. The loss factor tanδ of the composite material was tested by a dynamic mechanical analyzer to test the damping performance of the composite material. When tanδ>0.3, it indicates that the composite material has damping performance. The experimental results are as follows: Figure 2 shown.

[0058] Depend on Figure 2It can be seen that the in-situ grown inorganic lamellar particle reinforced and toughened polyurethane composite material of Example 1 exhibits relatively excellent damping performance, the temperature range of the damping performance is greater than 120°C, the softening temperature of the composite material is close to 140°C, and the maximum value of tanδ is higher than 0.6, but not greater than 0.7.

[0059] Experimental Example 3: Crystal Characterization

[0060] The in-situ grown inorganic lamellar particle reinforced toughened polyurethane composite material of Example 1 was tested, and the original sample and the sintered powder of the prepared composite material were subjected to XRD test, and the test results were compared with the standard card of the crystal in Jade 6. The experimental results are as follows: Figure 3 shown.

[0061] Depend on Figure 3 It can be seen that the in-situ grown inorganic lamellar particles reinforced and toughened polyurethane composite material in Example 1 of the present invention has good crystallinity. The composite material contains two crystals, hydroxyapatite and calcium hydrogen phosphate, while the powder after sintering basically contains only one crystal, hydroxyapatite, indicating that the preparation method of in-situ crystallization at the phase interface assisted by supercooled water can effectively prepare hydroxyapatite crystals.

[0062] Experimental Example 3: Structural Characterization

[0063] The in-situ grown inorganic lamellar particle reinforced toughened polyurethane composite material of Example 1 was tested by scanning electron microscope. The experimental results are as follows: Figure 4 shown.

[0064] Depend on Figure 4 It can be seen that an obvious lamellar structure appears in the in-situ grown inorganic lamellar particle reinforced and toughened polyurethane composite material of Example 1 of the present invention, which further proves that the preparation method of in-situ crystallization at the phase interface assisted by supercooled water can effectively prepare hydroxyapatite lamellar crystals.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing an in-situ grown inorganic lamellar particle reinforced and toughened polyurethane composite material, characterized in that: The following steps are involved: (1) dissolving tannic acid in deionized water and then freezing it to obtain ice cube A; the mass volume ratio of the tannic acid to the deionized water is 3-7 g:100 mL; (2) dissolving calcium chloride in deionized water and then freezing it to obtain ice cube B; the mass volume ratio of the calcium chloride to the deionized water is 3-7 g:100 mL; (3) dissolving disodium hydrogen phosphate dodecahydrate and sodium dihydrogen phosphate in deionized water to obtain solution C; the mass volume ratio of the disodium hydrogen phosphate dodecahydrate, sodium dihydrogen phosphate and deionized water is 1-4 g:0.5-3 g:100 mL; (4) blending the waterborne polyurethane, the solution C obtained in step (3) and the ice cube B obtained in step (2), stirring until the ice cubes are completely melted, then adding the ice cube A obtained in step (1), stirring until the ice cubes are completely melted, vacuum filtering and drying to obtain an in-situ grown inorganic lamellar particle reinforced and toughened polyurethane composite material; the mass volume ratio of the waterborne polyurethane to the solution C is 1-3g:35-75mL; the volumes of the solution C, the ice cube B and the ice cube A are the same in terms of liquid volume; and the solid content of the waterborne polyurethane is 20%-70%.

2. The method for preparing the in-situ grown inorganic lamellar particle reinforced and toughened polyurethane composite material according to claim 1, characterized in that: In steps (1) and (2), freeze in liquid nitrogen.

3. The method for preparing the in-situ grown inorganic lamellar particle reinforced and toughened polyurethane composite material according to claim 1, characterized in that: In step (4), filtration is performed using a PP filter membrane with a pore size of 0.22 μm.

4. The method for preparing the in-situ grown inorganic lamellar particle reinforced and toughened polyurethane composite material according to claim 1, characterized in that: In step (4), drying is performed at a temperature of 40-80°C.

5. An in-situ grown inorganic lamellar particle reinforced and toughened polyurethane composite material obtained by the method for preparing an in-situ grown inorganic lamellar particle reinforced and toughened polyurethane composite material according to any one of claims 1 to 4.

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