High-strength PET composite material and preparation method thereof

Abstract

The invention discloses a high-strength PET composite material and a preparation method thereof, and belongs to the technical field of high polymer materials, graphene aerogel is used as a matrix, a vinyl core-shell complex is loaded on the surface to obtain a functional complex / graphene aerogel, 1, 4-benzene diphosphonic acid and hydroxyethyl methylacrylate are grafted to obtain a flame-retardant functional ligand, and the flame-retardant functional ligand is used for preparing the high-strength PET composite material. The preparation method comprises the following steps: copolymerizing a functional complex / graphene aerogel, a flame-retardant functional ligand and double bonds in N-isopropylacrylamide to obtain three-dimensional net-shaped hydrogel, covering the functional complex / graphene aerogel with the three-dimensional net-shaped hydrogel, calcining to form a carbon layer by the three-dimensional net-shaped hydrogel on the outer layer, embedding the flame-retardant functional ligand into the carbon layer, and drying to obtain the flame-retardant graphene aerogel. Pores of the three-dimensional network hydrogel are smaller than pores of the functional complex / graphene aerogel, so that a gradient porous structure is formed, stress transition is realized through different pores, and formation of local stress concentration points is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and in particular relates to a high-strength PET composite material and a preparation method thereof. Background Art

[0002] Polyethylene terephthalate (PET), one of the five major general-purpose engineering plastics, has outstanding toughness, aging resistance, creep resistance, and resistance to friction and wear. It is the most produced and widely used type of thermoplastic linear saturated resin among polyesters. PET is lightweight, strong, airtight, highly transparent, and has excellent fatigue resistance, friction resistance, and aging resistance. It also has outstanding electrical insulation properties and possesses both certain rigidity and flexibility.

[0003] Currently, PET is primarily reinforced by adding glass fiber. However, glass fiber struggles to bond well with the PET matrix, resulting in floating fibers. Exposed glass fiber not only affects the material's performance but also the health of users. Consequently, Europe has implemented import restrictions on glass fiber-reinforced products. Finding alternatives or solutions for glass fiber reinforcement in PET to enhance and toughen PET has a significant impact on the expansion of PET composite applications.

[0004] Chinese patent application CN119775726A discloses a high-strength PET composite material and a preparation method thereof, which uses fumed silica as an inorganic material to improve PET. Compared with ordinary silica, fumed silica has stronger surface activity, is rich in silanol and siloxy groups, and already has a porous structure with a three-dimensional network. On this basis, fumed silica is added during the preparation of graphene aerogel. The siloxy groups on the surface of the fumed silica combine with the hydroxyl groups of the graphene oxide hydrogel. After heat treatment, a hybrid aerogel with a nanoporous carbon network structure and a lightweight nano-solid material filled with a large amount of gaseous dispersion medium in the network skeleton is formed. However, although the two are combined through silanol and hydroxyl groups, the graphene sheets are easily agglomerated due to π-π stacking, and the silica nanoparticles may be embedded in the stacking gaps, which in turn increases local stress concentration points and causes microcracks. Summary of the Invention

[0005] The present invention aims to provide a high-strength PET composite material and a preparation method thereof. Graphene aerogel is used as a matrix, a vinyl core-shell complex is loaded on the surface to obtain a functional complex / graphene aerogel, 1,4-phenylenediphosphonic acid is grafted with hydroxyethyl methacrylate to obtain a flame-retardant functional ligand, and the functional complex / graphene aerogel, the flame-retardant functional ligand and the double bonds in N-isopropylacrylamide are copolymerized under an initiator to obtain a three-dimensional network hydrogel covering the functional complex / graphene aerogel, the vinyl core-shell complex is fixed to the surface of the functional complex / graphene aerogel through the three-dimensional network hydrogel, and after calcination, the outer three-dimensional network hydrogel forms a carbon layer, the flame-retardant functional ligand is embedded in the carbon layer, the pores of the three-dimensional network hydrogel are smaller than the pores of the functional complex / graphene aerogel, thereby forming a gradient porous structure, achieving stress transition through different pores, and avoiding the formation of local stress concentration points.

[0006] The purpose of the present invention can be achieved through the following technical solutions: A method for preparing a high-strength PET composite material comprises the following steps: Step 1: 2-(Oxiran-2-yl)benzoic acid is used as a monomer to coordinate with ferric chloride to obtain an epoxy complex, and then amino groups are used to promote the ring opening of the epoxy group in the epoxy complex to obtain a silane-modified complex. After hydrolysis and condensation with vinyltriethoxysilane, a vinyl core-shell complex is obtained.

[0007] Step 2: Using 1,4-phenylenediphosphonic acid as a monomer, an esterification reaction is carried out with the hydroxyl group in hydroxyethyl methacrylate to obtain a flame retardant functional ligand.

[0008] Step 3: After mixing the graphene aerogel and the vinyl core-shell complex, a functional complex / graphene aerogel is obtained, and the functional complex / graphene aerogel, the flame retardant functional ligand and the double bond in isopropyl acrylamide are copolymerized and calcined under an initiator to obtain a functional hybrid filler.

[0009] Step 4: Melt the PET pellets, add the functional hybrid filler, talc nucleating agent, and antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], stir and mix, and extrude through a twin-screw extruder to obtain a high-strength PET composite material.

[0010] Furthermore, the usage ratio of PET particles, functional hybrid filler, talc and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate is 500-600 g: 20-30 g: 10-12 g: 8-10 g.

[0011] Furthermore, the specific preparation steps of the epoxy complex are as follows: 2-(Oxiran-2-yl)benzoic acid and deionized water are added to a polytetrafluoroethylene reactor, stirred at 20-25°C and 500-600 r / min for 20-30 minutes, then a mixed solution of sodium hexadecyl sulfate and 60-70wt% ethanol solution is added, heated to 120-130°C, and then ferric chloride is added. Stirring is continued for 8-9 hours, and the mixture is filtered. The filter cake is washed with deionized water and anhydrous ethanol for 2-4 times, respectively, and vacuum dried at 60-70°C for 1-2 hours to obtain an epoxy complex.

[0012] Furthermore, the usage ratio of 2-(oxiran-2-yl)benzoic acid, deionized water, sodium hexadecyl sulfate, ethanol solution and ferric chloride is 500-600 g: 800-900 mL: 18-20 g: 120-140 mL: 150-160 g.

[0013] Furthermore, the specific preparation steps of the silane-modified complex are as follows: Add the epoxy complex, γ-aminopropyltriethoxysilane and N,N-dimethylformamide into a reaction kettle, stir at 20-25°C and 500-600 r / min for 20-30 minutes, then add the catalyst triphenylphosphine, continue stirring for 1-2 hours, filter, wash the filter cake with deionized water and anhydrous ethanol 2-4 times respectively, and dry under vacuum at 60-70°C for 1-2 hours to obtain a silane-modified complex; Furthermore, the usage ratio of the epoxy complex, γ-aminopropyltriethoxysilane, N,N-dimethylformamide and triphenylphosphine is 400-500 g: 100-120 g: 4-5 L: 12-14 g.

[0014] Furthermore, the specific preparation steps of the vinyl core-shell complex are as follows: The silane-modified complex, vinyltriethoxysilane and acetone were added to a reactor, stirred at 40-50° C. and 400-500 r / min for 20-30 minutes, and then a 1 mol / L glacial acetic acid solution was added as a catalyst. The reaction was continued for 70-72 hours. The product was recrystallized in a mixed solution of acetone and dichloromethane with a volume ratio of 1:1, filtered, and the filter cake was washed with deionized water and anhydrous ethanol for 2-4 times, respectively, and dried in a vacuum at 60-70° C. for 1 hour to obtain a vinyl core-shell complex.

[0015] Furthermore, the usage ratio of the silane-modified complex, vinyltriethoxysilane, acetone and glacial acetic acid solution is 300-400 g: 250-260 g: 2-3 L: 17-18 mL.

[0016] Furthermore, the specific preparation steps of the flame retardant functional ligand are as follows: 1,4-Benzene diphosphonic acid, hydroxyethyl methacrylate and tetrahydrofuran are added to a reaction kettle, stirred at 20-25°C and 500-600 r / min for 20-30 minutes, anhydrous magnesium sulfate as a dehydrating agent and 98% concentrated sulfuric acid are added to the reaction system, stirring is continued for 24-26 hours, and the mixture is filtered. The filter cake is washed with deionized water and anhydrous ethanol for 2-4 times, respectively, and vacuum dried at 60-70°C for 1-2 hours to obtain a flame retardant functional ligand.

[0017] Furthermore, the usage ratio of 1,4-benzenediphosphonic acid, hydroxyethyl methacrylate, tetrahydrofuran, anhydrous magnesium sulfate and concentrated sulfuric acid is 100-120 g: 120-140 g: 2-4 L: 22-24 g: 2-3 mL.

[0018] Furthermore, the specific preparation steps of the functional complex / graphene aerogel are as follows: The graphene aerogel and the vinyl core-shell complex were dispersed in deionized water in a mass ratio of 10:3:100 and added to a reactor. The mixture was stirred at 20-25°C and 500-600 r / min for 1-2 hours, ultrasonically dispersed for 40-60 minutes, and filtered. The filter cake was washed with deionized water and anhydrous ethanol 2-4 times, respectively, and vacuum dried at 60-70°C for 1-2 hours to obtain a functional complex / graphene aerogel with an outer pore diameter of 40-50 nm of the vinyl core-shell complex and an inner layer of graphene aerogel of 100-300 nm.

[0019] Furthermore, the specific preparation steps of the functional hybrid filler are as follows: The functional complex / graphene aerogel, flame retardant functional ligand and N-isopropylacrylamide are added to a reactor, stirred at 20-25°C and 400-500 r / min for 20-30 minutes, heated to 70-80°C, and ammonium persulfate is added. Under a nitrogen atmosphere, stirring and reacting are continued for 6-7 hours. The mixture is filtered, and the filter cake is washed with petroleum ether and deionized water for 2-4 times, respectively, and vacuum dried at 60-70°C for 1-2 hours. The product is transferred to a muffle furnace, heated to 500-520°C under nitrogen protection, and calcined for 2-3 hours to obtain a functional hybrid filler.

[0020] Furthermore, the usage ratio of the functional complex / graphene aerogel, the flame retardant functional ligand, N-isopropylacrylamide and ammonium persulfate is 300-320 g: 120-140 g: 500-550 mL: 12-15 g.

[0021] Beneficial effects of the present invention: 1. The high-strength PET composite material prepared by the present invention is obtained by melt-extrusion of a self-synthesized functional hybrid filler and PET particles, so that it has good impact resistance, toughness and flame retardancy.

[0022] 2. The functional hybrid filler of the present invention uses graphene aerogel as a matrix and loads a vinyl core-shell complex on the surface to obtain a functional complex / graphene aerogel. 1,4-Benzenediphosphonic acid is grafted with hydroxyethyl methacrylate to obtain a flame-retardant functional ligand. The functional complex / graphene aerogel, the flame-retardant functional ligand and the double bonds in N-isopropylacrylamide are copolymerized under an initiator to obtain a three-dimensional network hydrogel covered on the functional complex / graphene aerogel with the functional complex / graphene aerogel as a carrier, the vinyl core-shell complex on the surface as a cross-linking center, and the flame-retardant functional ligand as an auxiliary cross-linking component. The vinyl core-shell complex is fixed on the surface of the functional complex / graphene aerogel through the three-dimensional network hydrogel and exists on the inner side of the hydrogel. After calcination, the outer three-dimensional network hydrogel forms a carbon layer, and the flame-retardant functional ligand is embedded in the carbon layer. The pores of the three-dimensional network hydrogel are smaller than the pores of the functional complex / graphene aerogel, thereby forming a gradient porous structure.

[0023] 3. Under high-temperature calcination, the internally wrapped vinyl core-shell complex will also become carbon nanospheres. Due to the formation of the outer carbon layer with small pores, the carbon nanospheres are allowed to disperse stress by rolling and slipping in the functional hybrid filler, and the gradient porous structure can achieve stress transition through different pores, further improving the mechanical properties of the PET composite material. The outer carbon layer is embedded with a flame-retardant functional ligand containing phosphorus elements, which cooperates with the internally wrapped carbon nanospheres to exert a flame-retardant effect. The gradient porosity can significantly increase gas convection, which is beneficial to reduce the ambient temperature while exerting the flame retardant effect. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0025] Example 1: A method for preparing a high-strength PET composite material, comprising the following steps: S1: Add 500 g of 2-(oxiran-2-yl)benzoic acid and 800 mL of deionized water into a polytetrafluoroethylene reactor and stir at 20°C and 500 r / min for 20 min. Then add a mixed solution of 18 g of sodium hexadecyl sulfate and 120 mL of 60 wt% ethanol solution. Heat to 120°C and add 150 g of ferric chloride. Continue stirring for 8 h. Filter with suction. Wash the filter cake twice with deionized water and anhydrous ethanol, respectively. Dry under vacuum at 60°C for 1 h to obtain the epoxy complex.

[0026] 2-(Oxiran-2-yl)benzoic acid coordinates with the iron ion in ferric chloride to give an epoxy complex.

[0027] S2: 400 g of epoxy complex, 100 g of γ-aminopropyltriethoxysilane and 4 L of N,N-dimethylformamide were added to a reactor, stirred at 20 ° C and 500 r / min for 20 min, then 12 g of catalyst triphenylphosphine was added, stirring was continued for 1 h, filtered, and the filter cake was washed twice with deionized water and anhydrous ethanol respectively, and dried in vacuum at 60 ° C for 1 h to obtain a silane-modified complex; 300 g of silane-modified complex, 250 g of vinyltriethoxysilane and 2 L of acetone were added to a reactor, stirred at 40 ° C and 400 r / min for 20 min, then 17 mL of glacial acetic acid solution with a concentration of 1 mol / L as a catalyst was added, and the reaction was continued for 70 h. The product was placed in a mixed solution of acetone and dichloromethane with a volume ratio of 1:1 for recrystallization, filtered, and the filter cake was washed twice with deionized water and anhydrous ethanol respectively, and dried in vacuum at 60 ° C for 1 h to obtain a vinyl core-shell complex.

[0028] The amino group of γ-aminopropyltriethoxysilane promotes the ring opening of the epoxy group in the epoxy complex under the action of the catalyst triphenylphosphine to obtain a silane-modified complex. The silane-modified complex contains silyl groups that undergo hydrolysis and condensation with vinyltriethoxysilane to obtain a cage-type polyhalf-siloxane coated on the surface of the epoxy complex to obtain a vinyl core-shell complex.

[0029] S3: Add 100 g of 1,4-benzenediphosphonic acid, 120 g of hydroxyethyl methacrylate and 2 L of tetrahydrofuran into a reactor, stir at 20°C and 500 r / min for 20 min, add 22 g of anhydrous magnesium sulfate as a dehydrating agent and 2 mL of 98% concentrated sulfuric acid into the reaction system, continue stirring for 24 h, filter, wash the filter cake twice with deionized water and anhydrous ethanol, respectively, and dry in vacuo at 60°C for 1 h to obtain a flame retardant functional ligand.

[0030] The phosphoric acid group in 1,4-phenylenediphosphonic acid undergoes esterification reaction with the hydroxyl group in hydroxyethyl methacrylate to obtain a flame retardant functional ligand.

[0031] S4: Graphene aerogel and vinyl core-shell complex were dispersed in deionized water in a mass ratio of 10:3:100 and added into the reactor. The mixture was stirred at 20°C and 500 r / min for 1 h, ultrasonically dispersed for 40 min, filtered, and the filter cake was washed twice with deionized water and anhydrous ethanol, respectively, and vacuum dried at 60°C for 1 h to obtain a functional complex / graphene aerogel with an outer pore size of 40-50 nm of vinyl core-shell complex and an inner layer of graphene aerogel of 100-300 nm.

[0032] S5: Add 300 g of functional complex / graphene aerogel, 120 g of flame retardant functional ligand and 500 mL of N-isopropylacrylamide into the reactor, stir at 20 ° C and 400 r / min for 20 min, heat to 70 ° C, add 12 g of ammonium persulfate, continue stirring and reacting for 6 h under nitrogen atmosphere, filter, wash the filter cake with petroleum ether and deionized water twice respectively, dry in vacuum at 60 ° C for 1 h, transfer the product to a muffle furnace, heat to 500 ° C under nitrogen protection, and calcine for 2 h to obtain a functional hybrid filler.

[0033] The functional complex / graphene aerogel, the flame retardant functional ligand and the double bonds in N-isopropylacrylamide are copolymerized under the action of ammonium persulfate and calcined to obtain a functional hybrid filler.

[0034] S6: 500 g of PET pellets were melted at 265° C., 20 g of a functional hybrid filler, 10 g of a talc nucleating agent, and 8 g of an antioxidant, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, were added, and the mixture was stirred at 500 rpm for 4 min. The mixture was then extruded through a twin-screw extruder at 265° C. to obtain a high-strength PET composite material.

[0035] Example 2: A method for preparing a high-strength PET composite material, comprising the following steps: S1: Add 550 g of 2-(oxiran-2-yl)benzoic acid and 850 mL of deionized water into a polytetrafluoroethylene reactor and stir at 22.5°C and 550 r / min for 25 min. Then, add a mixed solution of 19 g of sodium hexadecyl sulfate and 130 mL of 65 wt% ethanol solution. Heat to 125°C and add 155 g of ferric chloride. Continue stirring for 8.5 h and filter. Wash the filter cake with deionized water and anhydrous ethanol three times, respectively, and dry it in a vacuum at 65°C for 1.5 h to obtain the epoxy complex.

[0036] S2: 450g epoxy complex, 110g γ-Aminopropyltriethoxysilane and 4.5L N,N-dimethylformamide were added to the reactor, stirred at 22.5°C and 550r / min for 25min, then 13g of catalyst triphenylphosphine was added, stirring was continued for 1.5h, filtered, and the filter cake was washed with deionized water and anhydrous ethanol three times respectively, and dried in vacuum at 65°C for 1.5h to obtain a silane-modified complex; 350g of the silane-modified complex, 255g of vinyltriethoxysilane and 2.5L of acetone were added to the reactor, stirred at 45°C and 450r / min for 25min, then 17.5mL of glacial acetic acid solution with a concentration of 1mol / L as a catalyst was added, and the reaction was continued for 71h. The product was placed in a mixed solution of acetone and dichloromethane with a volume ratio of 1:1 for recrystallization, filtered, and the filter cake was washed with deionized water and anhydrous ethanol three times respectively, and dried in vacuum at 65°C for 1h to obtain a vinyl core-shell complex.

[0037] S3: Add 110 g of 1,4-benzenediphosphonic acid, 130 g of hydroxyethyl methacrylate and 3 L of tetrahydrofuran into a reactor, stir at 22.5 ° C and 550 r / min for 25 min, add 23 g of anhydrous magnesium sulfate as a dehydrating agent and 2.5 mL of 98% concentrated sulfuric acid to the reaction system, continue stirring for 25 h, filter, wash the filter cake with deionized water and anhydrous ethanol three times respectively, and dry in a vacuum at 65 ° C for 1.5 h to obtain a flame retardant functional ligand.

[0038] S4: Graphene aerogel and vinyl core-shell complex were dispersed in deionized water in a mass ratio of 10:3:100 and added to the reactor. The mixture was stirred at 22.5°C and 550 r / min for 1.5 h, ultrasonically dispersed for 50 min, filtered, and the filter cake was washed with deionized water and anhydrous ethanol three times respectively, and vacuum dried at 65°C for 1.5 h to obtain a functional complex / graphene aerogel with an outer pore size of 40-50 nm of vinyl core-shell complex and an inner layer of graphene aerogel of 100-300 nm.

[0039] S5: Add 310g of functional complex / graphene aerogel, 130g of flame retardant functional ligand and 525mL of N-isopropylacrylamide into the reactor, stir at 22.5℃ and 450r / min for 25min, heat to 75℃, add 13.5g of ammonium persulfate, continue stirring and reacting for 6.5h under nitrogen atmosphere, filter, wash the filter cake with petroleum ether and deionized water three times respectively, dry in vacuum at 65℃ for 1.5h, transfer the product to a muffle furnace, heat to 510℃ under nitrogen protection and calcine for 2.5h to obtain a functional hybrid filler.

[0040] S6: 550 g of PET pellets were melted at 267.5°C, and 25 g of a functional hybrid filler, 11 g of a talc nucleating agent, and 9 g of an antioxidant, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, were added. The mixture was stirred at 550 r / min for 4.5 min, and then extruded through a twin-screw extruder at 267.5°C to obtain a high-strength PET composite material.

[0041] Example 3: A method for preparing a high-strength PET composite material, comprising the following steps: S1: Add 600 g of 2-(oxiran-2-yl)benzoic acid and 900 mL of deionized water into a polytetrafluoroethylene reactor and stir at 25°C and 600 r / min for 30 min. Then add a mixed solution of 20 g of sodium hexadecyl sulfate and 140 mL of 70 wt% ethanol solution. Heat to 130°C and add 160 g of ferric chloride. Continue stirring for 9 h. Filter with suction. Wash the filter cake with deionized water and anhydrous ethanol four times, respectively. Dry under vacuum at 70°C for 2 h to obtain the epoxy complex.

[0042] S2: 500 g of epoxy complex, 120 g of γ-aminopropyltriethoxysilane and 5 L of N,N-dimethylformamide were added to a reactor, stirred at 25 ° C and 600 r / min for 30 min, then 14 g of catalyst triphenylphosphine was added, stirring was continued for 2 h, filtered, and the filter cake was washed with deionized water and anhydrous ethanol four times respectively, and dried in vacuum at 70 ° C for 2 h to obtain a silane-modified complex; 400 g of silane-modified complex, 260 g of vinyltriethoxysilane and 3 L of acetone were added to a reactor, stirred at 50 ° C and 500 r / min for 30 min, then 18 mL of glacial acetic acid solution with a concentration of 1 mol / L as a catalyst was added, and the reaction was continued for 72 h. The product was placed in a mixed solution of acetone and dichloromethane with a volume ratio of 1:1 for recrystallization, filtered, and the filter cake was washed with deionized water and anhydrous ethanol four times respectively, and dried in vacuum at 70 ° C for 1 h to obtain a vinyl core-shell complex.

[0043] S3: Add 120 g of 1,4-benzenediphosphonic acid, 140 g of hydroxyethyl methacrylate and 4 L of tetrahydrofuran into a reactor, stir at 25°C and 600 r / min for 30 min, add 24 g of anhydrous magnesium sulfate as a dehydrating agent and 3 mL of 98% concentrated sulfuric acid to the reaction system, continue stirring for 26 h, filter, wash the filter cake with deionized water and anhydrous ethanol four times respectively, and dry in a vacuum at 70°C for 2 h to obtain a flame retardant functional ligand.

[0044] S4: Graphene aerogel and vinyl core-shell complex were dispersed in deionized water in a mass ratio of 10:3:100 and added to the reactor. The mixture was stirred at 25°C and 600 r / min for 2 h, ultrasonically dispersed for 60 min, filtered, and the filter cake was washed 4 times with deionized water and anhydrous ethanol respectively, and vacuum dried at 70°C for 2 h to obtain a functional complex / graphene aerogel with an outer pore size of 40-50 nm of vinyl core-shell complex and an inner layer of graphene aerogel of 100-300 nm.

[0045] S5: Add 320g of functional complex / graphene aerogel, 140g of flame retardant functional ligand and 550mL of N-isopropylacrylamide into the reactor, stir at 25℃ and 500r / min for 30min, heat to 80℃, add 15g of ammonium persulfate, continue stirring and reacting for 7h under nitrogen atmosphere, filter, wash the filter cake with petroleum ether and deionized water 4 times respectively, dry in vacuum at 70℃ for 2h, transfer the product to a muffle furnace, heat to 520℃ and calcine for 3h under nitrogen protection to obtain a functional hybrid filler.

[0046] S6: 600g of PET pellets were melted at 270°C, 30g of functional hybrid filler, 12g of talc nucleating agent, and 10g of antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] were added, and stirred at 600r / min for 5min. The mixture was then extruded through a twin-screw extruder at 270°C to obtain a high-strength PET composite material. Comparative Example 1: Based on Example 3, the vinyl core-shell complex in step S2 is replaced by the epoxy complex in step S1.

[0047] Comparative Example 2: Based on Example 3, the flame retardant functional ligand in step S5 is replaced by 1,4-phenylenediphosphonic acid in step S3.

[0048] Comparative Example 3: Based on Example 3, the functional hybrid filler in step S6 is replaced by the functional complex / graphene aerogel in step S4.

[0049] The performance test of the high-strength PET composite material obtained in Examples 1-3 and Comparative Examples 1-3 was performed, and the results are shown in Table 1: 1. Tensile performance test: According to GB / T1040-2006 standard, high-strength PET composite material was made into tensile specimens with a gauge length of 20mm, 5mm width and 2mm thickness. The test was carried out at a tensile speed of 50mm / min. A total of 5 tests were conducted, and the obtained data were calculated as the average value.

[0050] 2. Impact performance test: According to GB / T1843-2008, high-strength PET composite materials were made into tensile splines with a gauge length of 80mm, 10mm width, and 4mm thickness. The cantilever beam pendulum impact test was performed with a V-notch in the spline and a pendulum energy of 2.75J. A total of five groups of splines were tested, and the obtained data were calculated as the average value.

[0051] 3. Limiting Oxygen Index (LOI) Test: This test is conducted in accordance with the national standard GB / T2406.2-2009. High-strength PET composite materials are made into tensile strips with a gauge length of 130mm, a width of 6.5mm, and a thickness of 3mm. The Limiting Oxygen Index refers to the minimum oxygen volume fraction concentration required when the strip burns in a nitrogen and oxygen atmosphere.

[0052] 4. Vertical burning test: The test is conducted according to the national standard ASTM D3801. High-strength PET composite materials are made into tensile test strips with a gauge length of 130mm, 13mm width and 3mm thickness. The materials are classified into V-0, V-1 and V-2 grades (V = vertical burning) based on the burning behavior of the test strips.

[0053] Table 1 project Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Tensile strength (MPa) 176.4 187.2 193.9 143.5 172.3 132.1 <![CDATA[Impact strength (KJ / m 2 )]]> 3.95 4.23 4.52 3.02 3.85 2.6 Oxygen index (%) 46 49 53 35 20 33 Vertical burning level (3mm) V-0 V-0 V-0 V-0 V-2 V-0 As can be seen from Table 1, the tensile strength, impact strength, and vertical burning rating of the high-strength PET composite material obtained in Examples 1-3 are significantly better than those of the comparative example, and the oxygen index is significantly lower than that of the comparative example, indicating that the high-strength PET composite material prepared by the present invention has excellent mechanical properties and flame retardant properties.

[0054] In Comparative Example 1, the vinyl core-shell complex is replaced by an epoxy complex. The vinyl core-shell complex is a core-shell structure. The vinyl contained on its surface can copolymerize with the flame retardant functional ligand and N-isopropylacrylamide to obtain a three-dimensional network hydrogel, which is then fixed on the surface of the functional complex / graphene aerogel. After calcination, the vinyl core-shell complex will become carbon nanospheres. Due to the formation of a carbon layer with small pores on the outer layer, the carbon nanospheres can disperse stress by rolling and sliding in the functional hybrid filler.

[0055] In Comparative Example 2, the flame-retardant functional ligand is replaced with 1,4-phenylenediphosphonic acid. 1,4-phenylenediphosphonic acid contains the flame-retardant element phosphorus. However, if 1,4-phenylenediphosphonic acid is added directly, it will agglomerate in the composite material and easily migrate during long-term use. After 1,4-phenylenediphosphonic acid is grafted with hydroxyethyl methacrylate, the double bonds contained in it participate in the formation of the three-dimensional network hydrogel and are embedded in the outer carbon layer after calcination, exerting a stable and long-lasting flame retardant effect.

[0056] In Comparative Example 3, the functional hybrid filler is replaced by a functional complex / graphene aerogel. The surface of the functional complex / graphene aerogel is covered with a three-dimensional network hydrogel and contains carbon nanospheres formed by a vinyl core-shell complex. The pores of the three-dimensional network hydrogel are smaller than those of the functional complex / graphene aerogel, thereby forming a gradient porous structure. The gradient porous structure can achieve stress transition through different pores, thereby further improving the mechanical properties of the PET composite material.

[0057] While the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations can be made to the embodiments without departing from the principles and spirit of the invention.

Claims

1. A method for preparing a high-strength PET composite material, characterized in that: The steps include: Step 1: The carboxyl group of 2-(oxiran-2-yl)benzoic acid is coordinated with ferric chloride to obtain an epoxy complex, and then the amino group is used to promote the ring opening of the epoxy group in the epoxy complex to obtain a silane-modified complex. After hydrolysis and condensation with vinyltriethoxysilane, a vinyl core-shell complex is obtained; Step 2: using 1,4-phenylenediphosphonic acid as a monomer to undergo esterification reaction with the hydroxyl group in hydroxyethyl methacrylate to obtain a flame retardant functional ligand; Step 3: After mixing the graphene aerogel and the vinyl core-shell complex to obtain a functional complex / graphene aerogel, copolymerizing the functional complex / graphene aerogel, the flame-retardant functional ligand and the double bond in isopropyl acrylamide in the presence of an initiator and calcining to obtain a functional hybrid filler; Step 4: Melt the PET pellets, add the functional hybrid filler, talc nucleating agent, and antioxidant pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], stir and mix, and extrude through a twin-screw extruder to obtain a high-strength PET composite material.

2. The method for preparing a high-strength PET composite material according to claim 1, wherein: The usage ratio of the PET particles, the functional hybrid filler, the talc powder and the pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate is 500-600g:20-30g:10-12g:8-10g.

3. The method for preparing a high-strength PET composite material according to claim 1, wherein: The specific preparation steps of the epoxy complex are as follows: 2-(Oxiran-2-yl)benzoic acid and deionized water are added to a polytetrafluoroethylene reactor, stirred at 20-25°C and 500-600 r / min for 20-30 minutes, then a mixed solution of sodium hexadecyl sulfate and 60-70wt% ethanol solution is added, heated to 120-130°C, and then ferric chloride is added. Stirring is continued for 8-9 hours, and the mixture is filtered. The filter cake is washed with deionized water and anhydrous ethanol 2-4 times, respectively, and dried in a vacuum at 60-70°C for 1-2 hours to obtain an epoxy complex. The usage ratio of the 2-(oxiran-2-yl)benzoic acid, deionized water, sodium hexadecyl sulfate, ethanol solution and ferric chloride is 500-600 g: 800-900 mL: 18-20 g: 120-140 mL: 150-160 g.

4. The method for preparing a high-strength PET composite material according to claim 1, wherein: The specific preparation steps of the silane-modified complex are as follows: Add the epoxy complex, γ-aminopropyltriethoxysilane and N,N-dimethylformamide into a reaction kettle, stir at 20-25°C and 500-600 r / min for 20-30 minutes, then add the catalyst triphenylphosphine, continue stirring for 1-2 hours, filter, wash the filter cake with deionized water and anhydrous ethanol 2-4 times respectively, and dry under vacuum at 60-70°C for 1-2 hours to obtain a silane-modified complex; The usage ratio of the epoxy complex, gamma-aminopropyltriethoxysilane, N,N-dimethylformamide and triphenylphosphine is 400-500g: 100-120g: 4-5L: 12-14g.

5. The method for preparing a high-strength PET composite material according to claim 1, characterized in that: The specific preparation steps of the vinyl core-shell complex are as follows: The silane-modified complex, vinyltriethoxysilane, and acetone were added to a reactor, stirred at 40-50° C. and 400-500 rpm for 20-30 min, and then a 1 mol / L glacial acetic acid solution was added as a catalyst. The reaction was continued for 70-72 h, and the product was recrystallized in a mixed solution of acetone and dichloromethane in a volume ratio of 1:

1. The product was filtered, and the filter cake was washed 2-4 times with deionized water and anhydrous ethanol, respectively, and dried in a vacuum at 60-70° C. for 1 h to obtain a vinyl core-shell complex. The usage ratio of the silane-modified complex, vinyltriethoxysilane, acetone and glacial acetic acid solution is 300-400 g: 250-260 g: 2-3 L: 17-18 mL.

6. The method for preparing a high-strength PET composite material according to claim 1, characterized in that: The specific preparation steps of the flame retardant functional ligand are as follows: 1,4-Benzene diphosphonic acid, hydroxyethyl methacrylate and tetrahydrofuran were added to a reaction kettle, stirred at 20-25°C and 500-600 r / min for 20-30 minutes, anhydrous magnesium sulfate as a dehydrating agent and 98% concentrated sulfuric acid were added to the reaction system, and stirring was continued for 24-26 hours. The mixture was filtered, and the filter cake was washed with deionized water and anhydrous ethanol for 2-4 times respectively, and vacuum dried at 60-70°C for 1-2 hours to obtain a flame retardant functional ligand. The usage ratio of the 1,4-benzenediphosphonic acid, hydroxyethyl methacrylate, tetrahydrofuran, anhydrous magnesium sulfate and concentrated sulfuric acid is 100-120 g: 120-140 g: 2-4 L: 22-24 g: 2-3 mL.

7. The method for preparing a high-strength PET composite material according to claim 1, characterized in that: The specific preparation steps of the functional complex / graphene aerogel are as follows: The graphene aerogel and the vinyl core-shell complex were dispersed in deionized water in a mass ratio of 10:3:100 and added to a reactor. The mixture was stirred at 20-25°C and 500-600 r / min for 1-2 hours, ultrasonically dispersed for 40-60 minutes, and filtered. The filter cake was washed with deionized water and anhydrous ethanol 2-4 times, respectively, and vacuum dried at 60-70°C for 1-2 hours to obtain a functional complex / graphene aerogel with an outer pore diameter of 40-50 nm of the vinyl core-shell complex and an inner layer of graphene aerogel of 100-300 nm.

8. The method for preparing a high-strength PET composite material according to claim 1, characterized in that: The specific preparation steps of the functional hybrid filler are as follows: The functional complex / graphene aerogel, flame retardant functional ligand and N-isopropylacrylamide are added to a reactor, stirred at 20-25°C and 400-500 r / min for 20-30 minutes, heated to 70-80°C, and ammonium persulfate is added. Under a nitrogen atmosphere, stirring and reacting are continued for 6-7 hours. The mixture is filtered, and the filter cake is washed with petroleum ether and deionized water for 2-4 times, respectively, and vacuum dried at 60-70°C for 1-2 hours. The product is transferred to a muffle furnace, heated to 500-520°C under nitrogen protection, and calcined for 2-3 hours to obtain a functional hybrid filler.

9. The method for preparing a high-strength PET composite material according to claim 8, characterized in that: The usage ratio of the functional complex / graphene aerogel, the flame retardant functional ligand, N-isopropylacrylamide and ammonium persulfate is 300-320 g: 120-140 g: 500-550 mL: 12-15 g.

10. A high-strength PET composite material, characterized in that: Prepared by the preparation method according to any one of claims 1 to 9.