An epoxy composite based on waste PET depolymerization product modified titanium dioxide and its preparation and application

Abstract

The application belongs to the technical field of epoxy composites, and discloses an epoxy composite based on waste PET depolymerization product modified titanium dioxide and a preparation and application thereof.The epoxy composite is made of the following raw materials in parts by weight: 100 parts of epoxy resin, 5-50 parts of modified titanium dioxide, 0.2-0.5 parts of catalyst and 5-20 parts of curing agent; the modified titanium dioxide is prepared by reacting 100 parts by weight of titanium dioxide precursor with 2-10 parts by weight of waste PET depolymerization product terephthalic acid and forming a gel by dropping ethanol aqueous solution, cleaning and drying.The method overcomes the poor compatibility of titanium dioxide with epoxy resin, easy agglomeration and other shortcomings, the dispersibility of the modified titanium dioxide in the epoxy resin is obviously improved, and the prepared epoxy composite has good dielectric properties and is used for packaging materials of electronic components and capacitor materials.

Description

Technical Field

[0001] This invention belongs to the field of functional polymer materials, specifically relating to a method for preparing and applying an epoxy composite material based on titanium dioxide modified with waste PET depolymerization products. Background Technology

[0002] Polyethylene terephthalate (PET) is a polymer that holds an important position in the world's plastics industry. It boasts numerous advantages, including good dimensional stability, excellent barrier and transparency properties, non-toxicity, odorlessness, and superior mechanical properties over a wide temperature range. However, with the increasing amount of PET waste and the inability to properly dispose of it, there is an urgent need to recycle waste PET. How to minimize its environmental harm has become a major concern.

[0003] The rapidly developing electronics industry relies heavily on the development of dielectric materials. However, traditional dielectric materials still suffer from problems such as low flexibility, hindering miniaturization design and processing, and high cost. Polymer dielectric materials, on the other hand, offer advantages such as low cost, good processability, and high toughness, overcoming the shortcomings of traditional dielectric materials. Epoxy resin is widely used in polymer dielectric materials, primarily in capacitors, dielectric elastomers, and thin-film transistors. However, epoxy resin alone still has limitations, such as low dielectric constant, high dielectric loss, and low energy density. Therefore, adding fillers with high dielectric constants to an epoxy resin matrix to prepare dielectric materials with high dielectric properties is the simplest method for obtaining high-dielectric epoxy composites.

[0004] Introducing inorganic fillers with high dielectric constants into epoxy resins is a common method for preparing epoxy composites with high dielectric constants. Traditional methods involve introducing a large amount of filler to obtain composites with high dielectric properties, but this often leads to problems such as filler agglomeration and difficulty in dispersion within the resin matrix, thus affecting the overall performance of the material and failing to meet application requirements such as high dielectric constant, low dielectric loss, and high energy density. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing an epoxy composite material based on titanium dioxide modified with waste PET depolymerization products, its preparation method, and its applications. This invention utilizes an alcohol-alkali combined method to depolymerize waste PET chips to prepare the depolymerization product terephthalic acid (TPA). The TPA is then used to modify titanium dioxide, improving the compatibility between the filler and the matrix, ultimately resulting in an epoxy composite material with excellent dielectric properties. The modified titanium dioxide (TPA@TiO2) of this invention exhibits superior performance compared to unmodified titanium dioxide, is less prone to agglomeration in the polymer matrix, and the prepared epoxy composite material possesses higher dielectric constant and energy storage density, as well as better bending properties. This invention not only recycles waste resources and reduces petroleum resource consumption but also broadens the application fields of the recovered depolymerization products, benefiting environmental protection and demonstrating promising development prospects. The epoxy composite material of this invention can be used in electronic component packaging materials, capacitor materials, and other fields.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An epoxy composite material based on titanium dioxide modified with waste PET depolymerization products is made from the following raw materials in parts by weight:

[0008]

[0009] The epoxy resin is one or both of E51 and E44.

[0010] The catalyst is triphenylphosphine (TPP).

[0011] The curing agent is one or more of ethylenediamine (EDA), diethylenetriamine (DETA), triethanolamine (TEA), and imidazole (IMD).

[0012] The method for preparing the epoxy composite material based on titanium dioxide modified with waste PET depolymerization products includes the following steps:

[0013] (1) Under stirring conditions, epoxy resin, modified titanium dioxide and catalyst are reacted at 100-160℃ to obtain composite material; the reaction time is 2-4h.

[0014] (2) Mix the composite material with the curing agent and cure to obtain the epoxy composite material.

[0015] The stirring speed in step (1) is 100-300 rpm.

[0016] The modified titanium dioxide (TPA@TiO2) is prepared by reacting 100 parts by weight of titanium dioxide precursor and 2-10 parts by weight of depolymerization product TPA, forming a gel by adding ethanol solution, washing, and drying.

[0017] The titanium dioxide precursor is one or both of tetrabutyl titanate and isopropyl titanate.

[0018] The modified titanium dioxide (TPA@TiO2) is obtained through the following preparation method:

[0019] (S1) Under stirring conditions, the titanium dioxide precursor and TPA were reacted at 80-120℃, and an aqueous ethanol solution was added dropwise to obtain a sol-gel. After washing and drying, modified titanium dioxide (TPA@TiO2) was obtained.

[0020] The reaction time described in step S1 is 1-2 hours, specifically until the solution becomes clear.

[0021] The ethanol-water solution should be added dropwise.

[0022] The mass concentration of the ethanol aqueous solution is 50%-95%.

[0023] The mass ratio of the ethanol aqueous solution to the titanium dioxide precursor is 10:1 to 3:1.

[0024] The cleaning refers to cleaning with anhydrous ethanol. The drying is carried out at 60-80℃ for 6-12 hours.

[0025] The curing conditions described in step (2) are: curing at 80-125°C for 1.5-2.5 hours.

[0026] The depolymerization product TPA, prepared from waste PET chips via an alcohol-alkali combined depolymerization method, is specifically composed of the following raw materials in parts by weight:

[0027]

[0028] The alcohol is one or both of ethylene glycol and glycerol.

[0029] The alkaline substance is one or more of sodium hydroxide, potassium hydroxide, and sodium bicarbonate.

[0030] The catalyst is one or both of zinc acetate and sodium ethoxide. The hydrochloric acid solution has a mass concentration of 38%.

[0031] The method for preparing depolymerization product TPA from waste PET chips via an alcohol-alkali combined depolymerization method includes the following steps:

[0032] (1) Under stirring conditions, waste PET chips are mixed with alcohols; alkaline substances and catalysts are added and mixed, and depolymerization reaction is carried out at 150-200℃. The mixture is filtered to obtain filtrate; the reaction time is 2-4 hours.

[0033] (2) Under stirring conditions, hydrochloric acid solution was slowly added to the filtrate, and a white precipitate appeared immediately. After repeated centrifugation and filtration, the product was washed alternately with anhydrous ethanol and water, dried, and ground to obtain the white crystalline depolymerization product TPA. The drying temperature was 60-80℃ and the time was 12-24h.

[0034] The stirring speed in step (1) is 100-300 rpm.

[0035] The stirring speed in step (2) is 100-300 rpm.

[0036] The terephthalic acid (TPA) of this invention is obtained by depolymerization of waste PET chips, which promotes the recycling of waste resources, reduces the consumption of petroleum resources, and is beneficial to environmental protection, showing good development prospects. Furthermore, the depolymerization product TPA is used to modify titanium dioxide, optimizing the compatibility between titanium dioxide and epoxy resin and improving its performance. Specifically, the epoxy composite material of this invention exhibits better dielectric and flexural properties compared to unmodified epoxy resin. In addition, the combination of these components and the aforementioned mixing range of each component were determined through extensive experiments.

[0037] The dispersion properties of modified titanium dioxide (TPA@TiO2) were analyzed by measuring the Zeta potential using a nanoparticle analyzer.

[0038] The dielectric properties of epoxy composite materials were tested using a wide-screen dielectric spectrometer.

[0039] The electrical breakdown performance of epoxy composite materials was tested using an electrical breakdown tester.

[0040] The flexural properties of epoxy composite materials were tested using a universal testing machine.

[0041] Compared with the prior art, the present invention has the following characteristics and superior effects:

[0042] 1. The TPA of the present invention is obtained by depolymerization of waste PET chips, which can better recycle waste PET materials, broaden the application field of waste PET materials, enrich the source of terephthalic acid (TPA), and reduce the consumption of petroleum resources.

[0043] 2. This invention uses TPA-modified titanium dioxide prepared by depolymerization of waste PET. First, TPA is reacted with the precursor of titanium dioxide, and then modified titanium dioxide (TPA@TiO2) is prepared by sol-gel method. The performance of the modified titanium dioxide is improved. At the same time, the dispersion and agglomeration of titanium dioxide in polymer matrix is ​​also improved.

[0044] 3. The epoxy composite material of this invention improves the dielectric properties of epoxy resin by using modified titanium dioxide, optimizing its dielectric constant and energy storage density. Compared to unmodified epoxy resin, the flexural properties of the epoxy composite material are also significantly improved. The epoxy composite material has strong application potential, broadening the application fields of epoxy resin and titanium dioxide in dielectric materials. Attached Figure Description

[0045] Figure 1 Process flow diagram for preparing depolymerization product TPA from waste PET;

[0046] Figure 2 Comparison of optimized process parameters for preparing TPA from waste PET depolymerization: a) Curve with reaction temperature as the variable, where reaction time, alkali dosage, and catalyst dosage are 2h, 40wt%, and 3wt%, respectively; b) Curve with reaction time as the variable, where reaction temperature, alkali dosage, and catalyst dosage are 190℃, 40wt%, and 3wt%, respectively; c) Curve with alkali dosage as the variable, where temperature, time, and catalyst dosage are constant, at 190℃, 3h, and 3wt%, respectively; d) Curve with catalyst dosage as the variable, where reaction temperature, reaction time, and alkali dosage are 190℃, 3h, and 50wt%, respectively.

[0047] Figure 3 The reaction mechanism diagram for the preparation of modified titanium dioxide (TPA@TiO2) and epoxy composite material E51 / TPA@TiO2 is shown.

[0048] Figure 4 Dispersion and surface morphology analysis of unmodified and modified titanium dioxide; (a) Dispersion effect of TiO2 (left) and TPA@TiO2 (right) in ethanol solution; (b) Zeta potential diagram; (c) Surface morphology of unmodified TiO2; (d) Surface morphology of modified TPA@TiO2;

[0049] Figure 5 Scanning electron microscope images of epoxy composite materials: (a) E51 / TiO2; (b) E51 / TPA@TiO2 prepared in Example 1;

[0050] Figure 6 The dielectric properties of epoxy composites with different TiO2 types are shown in (a) dielectric constant and (b) dielectric loss; the dielectric properties of epoxy composites with different TPA@TiO2 contents are shown in (c) dielectric constant and (d) dielectric loss; in (a) and (b), E51 / TPA@TiO2 was prepared in Example 1; in (c) and (d), E51 / TPA@TiO2-10 and E51 / TPA@TiO2-40 correspond to 10 parts by weight and 40 parts by weight of TPA@TiO2, respectively, and other conditions are the same as in Example 1;

[0051] Figure 7 (a) Weibull distribution curves and (b) energy storage density and electrical breakdown strength of epoxy composites with different TPA@TiO2 contents; E51 / TPA@TiO2-10 and E51 / TPA@TiO2-40 correspond to 10 parts by weight and 40 parts by weight of TPA@TiO2, respectively, with other conditions the same as in Example 1;

[0052] Figure 8 The bending properties of epoxy composites with different TiO2 types are shown in (a) flexural modulus and (b) flexural strength; the bending properties of epoxy composites with different TPA@TiO2 contents are shown in (c) flexural modulus and (d) flexural strength. In (a) and (b), E51 / TPA@TiO2 was prepared in Example 1. In (c) and (d), the TPA@TiO2 contents of 10 parts and 40 parts correspond to the amounts of TPA@TiO2 used, respectively, and other conditions are the same as in Example 1. Detailed Implementation

[0053] The following examples further illustrate the specific implementation of the present invention, but the implementation methods of the present invention are not limited thereto.

[0054] Flowchart of TPA preparation process from waste PET depolymerization, as shown below. Figure 1 As shown.

[0055] Figure 2 Comparison of optimized process parameters for preparing TPA from waste PET depolymerization: a) Curve with reaction temperature as the variable, where reaction time, alkali dosage, and catalyst dosage are 2h, 40wt%, and 3wt%, respectively; b) Curve with reaction time as the variable, where reaction temperature, alkali dosage, and catalyst dosage are 190℃, 40wt%, and 3wt%, respectively; c) Curve with alkali dosage as the variable, where temperature, time, and catalyst dosage are constant, at 190℃, 3h, and 3wt%, respectively; d) Curve with catalyst dosage as the variable, where reaction temperature, reaction time, and alkali dosage are 190℃, 3h, and 50wt%, respectively.

[0056] from Figure 2 The optimal depolymerization process parameters were obtained as follows: temperature 190℃, time 3h; alkali dosage 50wt%, catalyst dosage 5wt%. Under these parameters, the conversion rate of waste PET and the yield of TPA were the highest, reaching 94% and 86.1%, respectively.

[0057] Example 1: (1) 100 parts by weight of waste PET chips were added to 500 parts by weight of ethylene glycol solution (98% ethylene glycol aqueous solution). Then, 50% sodium hydroxide (50% refers to 50% of the PET mass) of alkali and 5% zinc acetate (5% refers to 5% of the PET mass) of catalyst were added to the solution. The reaction was carried out at 190°C for 3 hours. The solution was filtered and the clear liquid was taken off. 50 parts by weight of hydrochloric acid solution (38% concentration) was added to the filtrate to continuously precipitate the depolymerization product terephthalic acid (TPA) from the solution. After repeated centrifugation, filtration, washing with anhydrous ethanol and water alternately, drying, and grinding, white crystalline depolymerization product TPA was finally obtained.

[0058] (2) Mix 1.66 parts by weight of the depolymerization product TPA and 34 parts by weight of tetrabutyl titanate (TBT) and place them in a constant temperature oil bath at 120℃ for 1-2 hours. After the reaction is complete, slowly add 200 parts by weight of 75% ethanol solution until it becomes gel-like. Wash it with anhydrous ethanol several times, then dry it in an oven for 10 hours (drying temperature is 70℃). After repeated grinding, the modified titanium dioxide (TPA@TiO2) is finally obtained and set aside.

[0059] (3) 30 parts by weight of modified titanium dioxide (TPA@TiO2), 100 parts by weight of epoxy resin E51 and 0.3 parts by weight of catalyst triphenylphosphine (TPP) were placed in an oil bath at 120°C and stirred rapidly for 2 hours. After the reaction was complete and the temperature dropped to room temperature, 12 parts by weight of curing agent diethylenetriamine were added, mixed and poured into a mold and cured at 120°C for two hours to finally obtain epoxy composite material E51 / TPA@TiO2-30.

[0060] Figure 3 This is a schematic diagram of the reaction mechanism for the preparation of modified titanium dioxide (TPA@TiO2) and epoxy composite material E51 / TPA@TiO2.

[0061] Example 2

[0062] The depolymerization product TPA and the modified titanium dioxide (TPA@TiO2) are the same as in Example 1.

[0063] 20 parts by weight of modified titanium dioxide (TPA@TiO2), 100 parts by weight of epoxy resin E51 and 0.2 parts by weight of catalyst triphenylphosphine (TPP) were placed in an oil bath at 120°C and stirred rapidly for 2 hours. After the reaction was complete and the temperature dropped to room temperature, 12 parts by weight of curing agent diethylenetriamine were added and mixed. The mixture was poured into a mold and cured at 120°C for two hours to finally obtain epoxy composite material E51 / TPA@TiO2-20.

[0064] Example 3

[0065] The depolymerization product TPA and the modified titanium dioxide (TPA@TiO2) are the same as in Example 1.

[0066] 50 parts by weight of modified titanium dioxide (TPA@TiO2), 100 parts by weight of epoxy resin E51 and 0.5 parts by weight of catalyst triphenylphosphine (TPP) were placed in an oil bath at 120°C and stirred rapidly for 2 hours. After the reaction was complete and the temperature dropped to room temperature, 12 parts by weight of curing agent diethylenetriamine were added, mixed, poured into a mold, and cured at 120°C for two hours to finally obtain epoxy composite material E51 / TPA@TiO2-50.

[0067] Comparative Example 1

[0068] Mix 100 parts by weight of epoxy resin E51 and 12 parts by weight of diethylenetriamine, pour the mixture into a mold, and cure at 120°C for 2 hours.

[0069] Comparative Example 2

[0070] 50 parts by weight of tetrabutyl titanate (TBT) were slowly added dropwise with a 75% ethanol solution (200 parts by weight of ethanol solution) until it formed a gel. The gel was then washed repeatedly with anhydrous ethanol, dried in an oven for 6-12 hours, and repeatedly ground to obtain unmodified titanium dioxide (TiO2), which was then set aside. 30 parts by weight of unmodified titanium dioxide (TiO2), 100 parts by weight of epoxy resin E51, and 0.3 parts by weight of triphenylphosphine catalyst (TPP) were placed in an oil bath at 120°C and rapidly stirred for 2 hours. After the reaction was complete and the temperature cooled to room temperature, 12 parts by weight of the curing agent diethylenetriamine were added, mixed, poured into a mold, and cured at 120°C for two hours to obtain the epoxy composite material E51 / TiO2.

[0071] Comparative Example 3

[0072] The depolymerization product TPA was the same as in Example 1. Unmodified titanium dioxide (TiO2) was the same as in Comparative Example 2.

[0073] 30 parts by weight of unmodified titanium dioxide (TiO2), 5 parts by weight of TPA, 100 parts by weight of epoxy resin E51 and 0.3 parts by weight of catalyst triphenylphosphine (TPP) were placed in an oil bath at 120°C and stirred rapidly for 2 hours. After the reaction was complete and the temperature dropped to room temperature, 12 parts by weight of curing agent diethylenetriamine were added and mixed. The mixture was poured into a mold and cured at 120°C for 2 hours to finally obtain the epoxy composite material E51 / TPA / TiO2.

[0074] Figure 4Dispersion and surface morphology analysis of unmodified and modified titanium dioxide; (a) Dispersion effect of TiO2 (left) and TPA@TiO2 (right) in ethanol solution; (b) Zeta potential diagram; (c) Surface morphology of unmodified TiO2; (d) Surface morphology of modified TPA@TiO2;

[0075] Figure 5 Scanning electron microscope images of epoxy composite materials: (a) E51 / TiO2; (b) E51 / TPA@TiO2 prepared in Example 1;

[0076] In Examples 1, 2, and 3, the modified titanium dioxide (TPA@TiO2) was dissolved in anhydrous ethanol. While TiO2 rapidly precipitated in ethanol, TPA@TiO2 remained uniformly dispersed without significant precipitation. This indicates that TPA@TiO2 has better dispersibility in organic solvents (ethanol) than TiO2. Figure 4 As shown in (a), the modified titanium dioxide (TPA@TiO2) exhibits a larger absolute value of its Zeta potential, indicating a stronger repulsive force between molecules or particles, thus resulting in better dispersibility. Figure 4 As shown in (b). Secondly, the surface morphology of the modified titanium dioxide changed compared to the unmodified form, changing from the original round granules to a leaf-like shape with a sharper morphology, as shown in [example image]. Figure 4 As shown in (c) and (d). More importantly, unmodified titanium dioxide is more prone to agglomeration in the epoxy resin matrix and is not easy to disperse, while modified titanium dioxide did not show obvious agglomeration and was uniformly dispersed, as shown in... Figure 5 As shown.

[0077] Figure 6 The dielectric properties of epoxy composites with different TiO2 types are shown in (a) dielectric constant and (b) dielectric loss; the dielectric properties of epoxy composites with different TPA@TiO2 contents are shown in (c) dielectric constant and (d) dielectric loss; in (a) and (b), E51 / TPA@TiO2 was prepared in Example 1; in (c) and (d), E51 / TPA@TiO2-10 and E51 / TPA@TiO2-40 correspond to 10 parts by weight and 40 parts by weight of TPA@TiO2, respectively, and other conditions are the same as in Example 1;

[0078] Figure 7 (a) Weibull distribution curves and (b) energy storage density and electrical breakdown strength of epoxy composites with different TPA@TiO2 contents; E51 / TPA@TiO2-10 and E51 / TPA@TiO2-40 correspond to 10 parts by weight and 40 parts by weight of TPA@TiO2, respectively, with other conditions the same as in Example 1.

[0079] The dielectric constant, storage density, and flexural properties of the epoxy composites in Examples 1, 2, and 3 were significantly higher than those in Comparative Example 1. This indicates that the introduction of high dielectric constant fillers significantly improved the dielectric properties of the epoxy resin. Figure 6 As shown in Example 3, at an electric field frequency of 10... 2 At Hz, the dielectric constant of the epoxy composite material E51 / TPA@TiO2-50 reached 5.46, which is 75% higher than the dielectric constant (3.12) of Comparative Example 1. As in Example 1, the energy storage density of the epoxy composite material E51 / TPA@TiO2-30 reached 4.30 × 10⁻⁶. -2 J / cm 3 Compared to Comparative Example 1, this represents an increase of 43.3%, such as... Figure 7 As shown.

[0080] Figure 8 The bending properties of epoxy composites with different TiO2 types are shown in (a) flexural modulus and (b) flexural strength; the bending properties of epoxy composites with different TPA@TiO2 contents are shown in (c) flexural modulus and (d) flexural strength. In (a) and (b), E51 / TPA@TiO2 was prepared in Example 1. In (c) and (d), the TPA@TiO2 contents of 10 parts and 40 parts correspond to the amounts of TPA@TiO2 used, respectively, and other conditions are the same as in Example 1.

[0081] The epoxy composite materials in the examples all exhibited superior flexural properties compared to Comparative Example 1 (e.g., Figure 8 As shown in Example 3, the flexural modulus of the epoxy composite material E51 / TPA@TiO2-50 reached 2770 MPa, an increase of 166.6% compared to Comparative Example 1. The improved dispersion performance of the modified titanium dioxide prepared by the method of this invention is due to TPA acting as a modifier, improving the compatibility between titanium dioxide and epoxy resin. Consequently, the overall performance of the epoxy composite material is significantly improved.

Claims

1. An epoxy composite material based on titanium dioxide modified with waste PET depolymerization products, characterized in that: Made from the following raw materials in parts by weight: The modified titanium dioxide is prepared by reacting 100 parts by weight of titanium dioxide precursor with 2-10 parts by weight of waste PET depolymerization product terephthalic acid (TPA), and then forming a gel by adding an aqueous ethanol solution, followed by washing and drying. The titanium dioxide precursor is one or both of tetrabutyl titanate and isopropyl titanate. The mass concentration of the ethanol aqueous solution is 50%-95%.

2. The epoxy composite material based on titanium dioxide modified with waste PET depolymerization products according to claim 1, characterized in that: The modified titanium dioxide is obtained through the following preparation method: (S1) Under stirring conditions, titanium dioxide precursor and terephthalic acid were reacted at 80-120℃, and an aqueous ethanol solution was added dropwise to obtain a sol-gel. The sol-gel was washed and dried to obtain modified titanium dioxide.

3. The epoxy composite material based on titanium dioxide modified with waste PET depolymerization products according to claim 2, characterized in that: The reaction time described in step S1 is 1-2 hours, specifically until the solution becomes clear; the ethanol-water solution needs to be added slowly. The mass ratio of the aqueous ethanol solution to the titanium dioxide precursor is 10:1 to 3:

1. The cleaning refers to cleaning with anhydrous ethanol; the drying refers to drying at 60-80℃ for 6-12 hours.

4. The epoxy composite material based on titanium dioxide modified with waste PET depolymerization products according to claim 1, characterized in that: The epoxy resin is one or both of E51 and E44; The catalyst is triphenylphosphine; The curing agent is one or more of ethylenediamine, diethylenetriamine, triethanolamine, and imidazole.

5. The epoxy composite material based on titanium dioxide modified with waste PET depolymerization products according to claim 1, characterized in that: The depolymerization product TPA from waste PET chips is specifically made from the following raw materials in parts by weight: The alcohol is one or both of ethylene glycol and glycerol; The alkaline substance is one or more of sodium hydroxide, potassium hydroxide, and sodium bicarbonate; The catalyst is one or both of zinc acetate and sodium ethoxide; the hydrochloric acid solution has a mass concentration of 38%.

6. The epoxy composite material based on titanium dioxide modified with waste PET depolymerization products according to claim 5, characterized in that: The preparation method of the depolymerization product TPA from waste PET chips includes the following steps: (1) Under stirring conditions, waste PET chips are mixed with alcohols; alkaline substances and catalysts are added and mixed, and depolymerization reaction is carried out at 150-200℃. The mixture is then filtered to obtain the filtrate. (2) Under stirring conditions, hydrochloric acid solution was slowly added to the filtrate, and a white precipitate appeared. After repeated centrifugation and filtration, the product was washed with anhydrous ethanol and water alternately, dried, and ground to obtain the white crystalline depolymerization product TPA.

7. The epoxy composite material based on titanium dioxide modified with waste PET depolymerization products according to claim 6, characterized in that: The reaction time in step (1) is 2-4 h; the drying temperature in step (2) is 60-80℃ and the time is 12-24 h.

8. The method for preparing epoxy composite materials based on titanium dioxide modified with waste PET depolymerization products according to any one of claims 1 to 7, characterized in that: Includes the following steps: (1) Under stirring conditions, epoxy resin, modified titanium dioxide and catalyst are reacted at 100-160℃ to obtain composite material; (2) Mix the composite material with the curing agent and cure to obtain the epoxy composite material.

9. The method for preparing epoxy composite material based on titanium dioxide modified with waste PET depolymerization products according to claim 8, characterized in that: The reaction time described in step (1) is 2 to 4 hours.

10. The application of the epoxy composite material based on titanium dioxide modified with waste PET depolymerization products according to any one of claims 1 to 7, characterized in that: The epoxy composite material based on titanium dioxide modified with waste PET depolymerization products is used in the fields of electronic component packaging materials and capacitor materials.

Images