MIL-101 (Fe) / DE modified phenolic resin composite material and preparation method thereof

Abstract

The invention discloses an MIL-101 (Fe) / DE modified phenolic resin composite material and a preparation method thereof. According to the method, an MIL-101 (Fe) metal organic framework material is subjected to in-situ growth on the surface of diatomite through a hydrothermal method to form an MIL-101 (Fe) / DE composite material, and the MIL-101 (Fe) / DE composite material is added into phenolic resin as a nanofiller to obtain the MIL-101 (Fe) / DE modified phenolic resin composite material. The preparation method is simple, the MIL-101 (Fe) / DE composite material can be fully dispersed in the phenolic resin, the decomposition rate of a matrix is slowed down, and the fire resistance of the phenolic resin is improved.

Description

Technical Field

[0001] The present invention belongs to the field of composite materials, and relates to a MIL-101(Fe) / DE modified phenolic resin composite material and a preparation method thereof. Background Art

[0002] As a kind of thermosetting resin with excellent mechanical properties and thermal properties, phenolic resin has outstanding bonding properties after curing, and has excellent properties such as strong thermal stability and high char residue. Its cost is low, raw materials are easy to obtain, and the process and production equipment are simple. Therefore, it is widely used as the resin matrix of high-temperature resistant composite adhesives. Phenolic resin has become an indispensable polymer material in the fields of electronics, machinery, architecture, aerospace, military and national defense. Due to the limitation of its own structure (the main chain of the molecule is composed of C-C bonds), the phenolic hydroxyl groups and methylene groups in the molecular structure of unmodified phenolic resin are easily oxidized. When the use temperature of phenolic resin exceeds 250 °C, serious thermal decomposition will occur, affecting its heat resistance and antioxidant properties, resulting in a serious decline in the bonding strength of phenolic resin. Therefore, the bonding strength of alloy bonding components will suddenly decrease due to the thermal oxidative degradation of the adhesive resin matrix in a specific temperature range (usually 350-500 °C). To ensure the high-strength bonding of alloy components in the range of 350-500 °C, higher requirements are put forward for the high-temperature bonding performance and thermal oxidation resistance of phenolic resin as the adhesive resin matrix.

[0003] In recent years, highly crystalline materials and metal-organic frameworks (MOFs) composed of metal ions and organic linkers have been widely used as new flame retardants for various polymers (MOF / polymers). MOFs have a rich variety of transition metals, flame retardant elements and potential carbon sources, and their structures and properties are easy to adjust, making MOF and its derivatives and MOF hybrid materials have broad prospects in flame retardancy research. At the same time, the abilities of MOF such as adsorbing and removing harmful substances, acting as a potential carbon source and effective catalytic performance make it show application potential in the flame retardancy of polymer composites. However, the limited flame retardant efficiency of MOF itself indicates that although it has potential flame retardant characteristics, directly using MOF as a new flame retardant does not quite meet the high standards in the field of flame retardancy.

[0004] Diatomite (DE) contains a large amount of silicon dioxide (SiO2), which can exhibit excellent refractory properties at high temperatures. When exposed to flames or high-temperature conditions, the microporous structure of diatomite will prevent heat conduction and slow down the spread of fire, thus playing a role in flame retardancy. In addition, diatomite itself does not burn, which can reduce the generation of smoke and toxic gases in fires. Summary of the Invention

[0005] The object of the present invention is to provide a MIL-101(Fe) / DE modified phenolic resin composite material and a preparation method thereof. This method uses a composite material of an iron-based metal-organic framework complex (MIL-101(Fe)) and diatomite as a nano filler to modify the phenolic resin. Through the synergistic effect of MIL-101(Fe) and diatomite, the decomposition rate of the matrix is slowed down, and the fire resistance of the phenolic resin is improved.

[0006] The technical solution for achieving the object of the present invention is as follows:

[0007] A preparation method of a MIL-101(Fe) / DE modified phenolic resin composite material, the specific steps are as follows:

[0008] (1) Synthesis of MIL-101(Fe) / DE: According to the ratio of ferric chloride hexahydrate, terephthalic acid and diatomite of 10 mmol: 5 mmol: 0.5 g, dissolve ferric chloride hexahydrate, terephthalic acid and diatomite in N,N-dimethylformamide (DMF), ultrasonically mix them evenly, and then carry out a solvothermal reaction at 110 - 140 °C. After the reaction is completed, centrifugally wash the reaction product with DMF and absolute ethanol, and dry it to obtain an iron-based metal-organic framework complex / diatomite composite material (MIL-101(Fe) / DE);

[0009] (2) Preparation of the modified phenolic resin composite material: Ultrasonically disperse the MIF-101(Fe) / DE composite material in acetone to obtain a suspension, then add phenolic resin (PF) to the suspension, stir to mix them evenly, add a curing agent, and cure at 60 - 140 °C to obtain a PF / Fe / DE composite material.

[0010] Preferably, in step (1), the ultrasonic time is 30 min.

[0011] Preferably, in step (1), the reaction temperature is 120 °C and the reaction time is 20 h.

[0012] Preferably, in step (1), the centrifugal speed is 8000 r / min, the centrifugal time is 7 min, and the drying temperature is 60 - 80 °C.

[0013] Preferably, in step (2), the mass of the MIF-101(Fe) / DE composite material is 1% of the mass of the phenolic resin.

[0014] Preferably, in step (2), in the suspension, the concentration of the MIF-101(Fe) / DE composite material is 10 mg / ml.

[0015] The present invention also provides a MIL-101(Fe) / DE modified phenolic resin composite material prepared by the above preparation method.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] The present invention selects iron-based metal-organic framework compounds and diatomite, combining the excellent flame retardant properties of transition metals and the porosity of diatomite. It can not only play a synergistic role to improve the flame retardant effect and effectively delay the thermal decomposition rate of phenolic resin, but also be widely applied to polymer materials such as polyurethane, epoxy resin, and polypropylene to improve the flame retardant properties of polymer materials and reduce the possibility of casualties. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 are the scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) diagrams of diatomite;

[0019] Figure 2 are the scanning electron microscope and energy dispersive spectroscopy diagrams of MIL-101(Fe);

[0020] Figure 3 are the scanning electron microscope and energy dispersive spectroscopy diagrams of MIL-101(Fe) / DE;

[0021] Figure 4 are the X-ray diffraction (XRD) spectra of diatomite, MIL-101(Fe), and MIL-101(Fe) / DE;

[0022] Figure 5 is the pore size distribution and N2 isothermal adsorption-desorption diagram of MIL-101(Fe);

[0023] Figure 6 is the pore size distribution and N2 isothermal adsorption-desorption diagram of MIL-101(Fe) / DE;

[0024] Figure 7 are the thermogravimetric (TG) spectra of MIL-101(Fe) and MIL-101(Fe) / DE in N2 atmosphere;

[0025] Figure 8 are the thermogravimetric spectra of MIL-101(Fe) and MIL-101(Fe) / DE in O2 atmosphere;

[0026] Figure 9 are the thermogravimetric spectra of PF, PF / Fe, and PF / Fe / DE in N2 atmosphere;

[0027] Figure 10 are the thermogravimetric spectra of PF, PF / Fe, and PF / Fe / DE in O2 atmosphere;

[0028] Figure 11 are the scanning electron microscope and XRD diagrams of the composite material prepared in Comparative Example 1. Detailed implementation manners

[0029] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] MIL-101(Fe) was prepared according to the reference [Lan Mingyan, Zhang Xiuwu, Chu Hongyu, Wang Chongchen. Catalytic removal of pollutants by MIL-101(Fe) and its composites: synthesis, performance and mechanism [J]. Progress in Chemistry, 2023, 35(3): 458-474.].

[0031] Example 1

[0032] 1. Synthesis of MIL-101(Fe) and MIL-101(Fe) / DE

[0033] Synthesis of MIL-101(Fe): Weigh 2.7 g (10 mmol) of ferric chloride hexahydrate and 0.83 g (5 mmol) of terephthalic acid and dissolve them in 60 ml of N,N-dimethylformamide (DMF) solvent. Ultrasonically mix for 30 min until completely dissolved, then transfer to a 100 mL stainless steel autoclave lined with polytetrafluoroethylene and heat at 120 °C for 20 h to obtain MIL-101(Fe). Wash the above product mixture 3 times each with DMF and absolute ethanol (8000 r / min, 7 min).

[0034] Synthesis of MIL-101(Fe) / DE: The synthesis is the same as that of MIL-101(Fe) above, except that 0.5 g of diatomite is also added to the raw materials.

[0035] 2. Preparation of modified phenolic resin composites

[0036] Weigh 0.1 g of MIL-101(Fe) or MIL-101(Fe) / DE and disperse it in acetone, and perform ultrasonic treatment to obtain a suspension; add 1 g of phenolic resin to the suspension and stir continuously to obtain a mixture of MIL-101(Fe) or MIL-101(Fe) / DE and phenolic resin; then add 0.1 g of curing agent, and then cure at 90 °C to obtain PF / MIL-101(Fe) or PF / Fe / DE composites.

[0037] The synthesized MIL-MIL-101(Fe) and MIL-101(Fe) / DE were characterized in many aspects by an X-ray diffractometer, a nitrogen adsorption-desorption specific surface area analyzer, a scanning electron microscope and an energy spectrometer, and the thermal decomposition of MIL-101(Fe) and MIL-101(Fe) / DE as well as PF / Fe and PF / Fe / DE composites in different atmospheres (N2, O2) was tested by a thermogravimetry / differential scanning calorimetry synchronous thermal analyzer.

[0038] Figure 1 Scanning electron microscope and energy spectrum analysis diagrams of diatomite. From Figure 2 it can be seen that MIL-101(Fe) presents a combination of needle-shaped crystals and polyhedral shapes; while for MIL-101(Fe) / DE, MIL-101(Fe) grows on the surface of diatomite. Compared with Figure 2 , from Figure 3 it can be seen that most of the MIL-101(Fe) in MIL-101(Fe) / DE presents a polyhedral shape, indicating that diatomite is beneficial to the growth of its crystals.

[0039] Figure 4 It can be seen that the XRD results of the synthesized MIL-101(Fe) and MIL-101(Fe) / DE of the present invention are consistent with those of the reported MIL-101(Fe) and DE in the literature, indicating that the hydrothermal method can well prepare metal-organic framework materials, and the addition of diatomite does not change the properties of the material itself.

[0040] Figure 5 , 6 shows the test results of the nitrogen adsorption-desorption isotherms of the prepared MIL-101(Fe) and MIL-101(Fe) / DE, and studies whether parameters such as specific surface area are significantly affected after MIL-101(Fe) grows on diatomite. As Figure 6 shown, the N2 adsorption isotherm is of type "I", and the N2 adsorption rate increases rapidly with strong adsorption at P / P0 = 0.01.

[0041] Figure 7 , 8 shows the TG curves of the prepared MIL-101(Fe) and MIL-101(Fe) / DE in N2 and O2 atmospheres. It can be seen that the addition of diatomite mainly affects the degradation rate in the range of 200 - 500 °C, resulting in a decrease in the overall degradation rate and an increase in the final residue.

[0042] Figure 9 , 10 shows the TG curves of the prepared PF, PF / Fe and PF / Fe / DE composites in N2 and O2 atmospheres. It can be seen that compared with pure phenolic resin, in both atmospheres, after adding MIL-101(Fe) and MIL-101(Fe) / DE, in the range of 200 - 500 °C, the residual carbon content of the composites increases, indicating that the addition of nano-fillers can effectively increase the thermal oxidation resistance of phenolic resin and make it have high-strength adhesion in this temperature range.

[0043] Comparative Example 1

[0044] This comparative example is substantially the same as Example 1, except that the addition amount of diatomaceous earth is 1 g.

[0045] From Figure 11 It can be seen that the presence of a large amount of diatomaceous earth results in the inhomogeneity of the in-situ growth of MIL-101(Fe), and when tested by XRD, the diffraction intensity is low and the noise is large, making it impossible to accurately judge the synthesis of the composite material.

Claims

1. Preparation method of MIL-101(Fe) / DE modified phenolic resin composite material, characterized in that, The specific steps are as follows: (1) Synthesis of MIL-101(Fe) / DE: According to the ratio of ferric chloride hexahydrate, terephthalic acid and diatomite of 10 mmol: 5 mmol: 0.5 g, dissolve ferric chloride hexahydrate, terephthalic acid and diatomite in DMF, ultrasonically mix them evenly, and then carry out a solvothermal reaction at 110 - 140 °C. After the reaction, centrifuge and wash the reaction product with DMF and absolute ethanol, and dry to obtain the MIL-101(Fe) / DE composite material; (2) Preparation of modified phenolic resin composite material: Ultrasonically disperse the MIF-101(Fe) / DE composite material in acetone to obtain a suspension, then add phenolic resin to the suspension, stir to mix evenly, add a curing agent, and cure at 60 - 140 °C to obtain the PF / Fe / DE composite material.

2. The preparation method according to claim 1, characterized in that, In step (1), the ultrasonic time is 30 min.

3. The preparation method according to claim 1, characterized in that, In step (1), the reaction temperature is 120 °C and the reaction time is 20 h.

4. The preparation method according to claim 1, wherein In step (1), the centrifugation speed is 8000 r / min, the centrifugation time is 7 min, and the drying temperature is 60 - 80 °C.

5. The preparation method according to claim 1, characterized in that, In step (2), the mass of the MIF-101(Fe) / DE composite material is 1% of the mass of the phenolic resin.

6. The preparation method according to claim 1, characterized in that In step (2), in the suspension, the concentration of the MIF-101(Fe) / DE composite material is 10 mg / ml.

7. The prepared MIL-101(Fe) / DE modified phenolic resin composite material according to any one of claims 1 to 6.

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