CN112694630A - Discontinuous fiber reinforced poly-hexahydrotriazine resin-based heat-conducting composite material and preparation method thereof - Google Patents
Discontinuous fiber reinforced poly-hexahydrotriazine resin-based heat-conducting composite material and preparation method thereof Download PDFInfo
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Abstract
The invention belongs to the field of thermosetting resin-based composite materials, and discloses a discontinuous fiber reinforced poly-hexahydrotriazine resin-based heat-conducting composite material and a preparation method thereof, wherein the method comprises the steps of uniformly dissolving formaldehyde and aromatic amine in a water/aprotic solvent mixed solution, carrying out prepolymerization on obtained reaction liquid to obtain a prepolymer solution, uniformly mixing a heat-conducting filler and discontinuous fibers in the prepolymer solution, adding a solvent for precipitation, and filtering and drying to obtain a prepreg; or pre-polymerizing formaldehyde and aromatic amine in an aprotic/water mixed solvent, adding a solvent for precipitation, drying to obtain a powdery prepolymer, and uniformly mixing the powdery prepolymer, a heat-conducting filler and discontinuous fibers to obtain a prepreg; carrying out hot-pressing curing molding on the prepreg to obtain a composite material; the aromatic amine is aromatic diamine containing at least one aromatic amide or aromatic ester structure. The composite material has excellent mechanical and heat-conducting properties, and the preparation process is simple, and the prepared composite material can be recycled.
Description
Technical Field
The invention relates to the field of thermosetting resin-based composite materials, in particular to a recyclable discontinuous fiber reinforced poly-hexahydrotriazine heat-conducting composite material and a preparation method thereof.
Background
The thermosetting polymer-based composite material has the characteristics of excellent mechanical strength, good corrosion resistance, excellent insulating property and the like, and is widely applied to the fields of microelectronic packaging, aerospace, military and national defense and the like. However, the thermosetting resin matrix has poor heat conductivity, and the thermal conductivity of the common epoxy resin is about 0.2W/(m.K), so that the overall heat conductivity of the composite material is not high. In addition, in the preparation process of the composite material, a cross-linked network or body-type cross-linked structure with irreversible transformation is formed among matrix resin molecules or molecular chains, and the composite material has the characteristics of being incapable of melting and plasticizing by heating and being insoluble in a solvent. Therefore, thermosetting polymer resins and their composites cannot be recycled by means of dissolution and melting like thermoplastic resins. The waste is generally buried or incinerated, which not only causes huge waste to resources, but also has great threat to environmental and ecological safety.
Disclosure of Invention
The invention aims to provide a recyclable discontinuous fiber reinforced poly-hexahydrotriazine heat-conducting composite material, which is prepared by pre-polymerizing formaldehyde and aromatic amine in a water/aprotic solvent mixed solution to prepare a prepolymer solution, uniformly mixing a heat-conducting filler and discontinuous fibers in the prepolymer solution, adding a solvent for precipitation, filtering and drying to obtain a prepreg A, or pre-polymerizing formaldehyde and aromatic amine in a water/aprotic solvent mixed solution, adding a solvent for precipitation, drying to obtain a powdery prepolymer, and uniformly mixing the powdery prepolymer with the heat-conducting filler and the discontinuous fibers to obtain a prepreg B. And placing the prepreg A or B into a mould for hot-press molding, and demoulding to obtain the composite material.
The invention realizes the purpose of recycling the fiber, the heat-conducting filler and the main raw material aromatic amine by utilizing the characteristic that the hexahydrotriazine structure can be depolymerized in the strong acid/aprotic solvent mixed solution.
The purpose of the invention is realized by the following technical scheme:
a preparation method of a discontinuous fiber reinforced poly-hexahydrotriazine resin-based heat-conducting composite material comprises the following steps:
(1) uniformly dissolving formaldehyde and aromatic amine in a water/aprotic solvent mixed solution, stirring the obtained reaction solution at 30-100 ℃ to react for 5-120 minutes to perform prepolymerization to obtain a prepolymer solution, uniformly mixing a heat-conducting filler and discontinuous fibers in the prepolymer solution, adding a solvent to perform precipitation, and filtering and drying to obtain a prepreg A;
or pre-polymerizing formaldehyde and aromatic amine in a water/aprotic solvent mixed solution, adding a solvent for precipitation, drying to obtain a powdery prepolymer, and uniformly mixing the powdery prepolymer, a heat-conducting filler and discontinuous fibers to obtain a prepreg B;
the aromatic amine is aromatic diamine at least containing an aromatic amide or aromatic ester structure;
(2) and (3) carrying out hot-pressing curing molding on the prepreg A or B to obtain the composite material.
The hot-pressing curing molding process comprises the following steps: heating to 140-180 ℃ at a heating rate of 5-20 ℃/min, preserving heat for 0.5-1 hour, pressurizing to 0.5-7 MPa, exhausting for 1-2 times, keeping the pressure unchanged, heating to 190-250 ℃ at a heating rate of 1-10 ℃/min, preserving heat for 0.5-3 hours, cooling to below 100 ℃ at a heating rate of 1-5 ℃/min, and demolding.
The discontinuous fiber is any one or more than two of long fiber with the length of 10-25mm, short fiber with the length of 2-3mm and powder fiber with the length of less than 2 mm.
The fiber type comprises one or more than two of carbon fiber, graphite fiber, glass fiber, aramid fiber, quartz fiber, basalt fiber, ceramic fiber, polybenzoxazole fiber and polybenzimidazole fiber.
The heat-conducting filler is one or more than two of alumina particles, aluminum nitride particles, silicon nitride particles, boron nitride particles, silicon carbide particles, magnesium oxide particles, zinc oxide particles, silicon dioxide particles, barium titanate particles, aluminum hydroxide particles, titanium dioxide particles, gold particles, silver particles, copper particles, aluminum particles, iron particles, zinc particles, nickel particles, nano carbon fibers, diamond, graphite, carbon black, carbon nano tubes, graphene and graphite alkyne.
The molar ratio of the formaldehyde to the primary amino groups in the aromatic amine is 1:1, i.e. the molar ratio of formaldehyde to aromatic diamine is 2: 1.
the aromatic amine is one or more than two of the following structures:
the other types of aromatic amines used in combination with aromatic amines having aromatic amide and aromatic ester structures are not limited, and the following can be exemplified: p-phenylenediamine, m-phenylenediamine, 4 '-diaminodiphenyl ether, 3,4' -diaminodiphenyl ether, 4 '-diaminobenzophenone, 4' -diaminodiphenyl sulfone, 3,4 '-diaminodiphenyl sulfone, 4' -diaminodiphenylmethane, 4,4'- (9-fluorenylidene) diphenylamine, benzidine, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 2-bis [4- (4-aminophenoxy benzene) ] hexafluoropropane, bis [4- (4-aminophenoxy) phenyl ] sulfone, 4' -bis (4-aminophenoxy) biphenyl, 1, 4-bis (4-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene.
The aprotic solvent is one or more than two of N-methylpyrrolidone, dimethylformamide, N-dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, 2, 5-dimethylfuran and hexamethylphosphoramide; the volume content of water in the mixed solvent is 0.5-60%. The solvent of the precipitation prepolymer is one or more than two of water, ethanol, ether, acetone and petroleum ether.
The composite material comprises, by mass, 10% -95% of the polyhexahydrotriazine resin, 4.5% -75% of the discontinuous fiber and 0.5% -85% of the heat-conducting filler.
The composite material is soaked in a strong acid/aprotic solvent mixed solution, fibers are filtered from a degraded acid solution through a screen, and the fibers are obtained by drying after being washed by water, an alkali solution and water and recovered; further filtering the degraded acid solution by using quantitative filter paper, washing with water, an alkali solution and water, drying, and recovering to obtain the heat-conducting filler; and finally, neutralizing the degraded acid solution with an alkali solution, precipitating, filtering, washing with water, and drying to obtain the aromatic amine.
The strong acid is sulfuric acid or hydrochloric acid, and the alkali solution is saturated solution of sodium carbonate or sodium bicarbonate; the using amount of the strong acid/aprotic solvent mixed solution is 5-30 ml per gram of the composite material, the concentration of the strong acid is 0.5-12 mol/L, the aprotic solvent is one or more than two of N-methylpyrrolidone, dimethylformamide, N-dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, 2, 5-dimethylfuran and hexamethylphosphoramide, and the soaking temperature is 20-95 ℃ for 0.5-24 hours.
A discontinuous fiber reinforced poly-hexahydrotriazine resin-based heat-conducting composite material comprises discontinuous fibers, heat-conducting filler and a poly-hexahydrotriazine resin matrix, wherein the structural formula of the matrix is as follows:
the R is1、R2、R3Is any one of the following structures:
compared with the prior art, the invention has the following advantages and beneficial effects:
(1) the discontinuous fiber reinforced poly-hexahydrotriazine heat-conducting composite material prepared by the invention has excellent mechanical and heat-conducting properties. The tensile strength and the modulus respectively reach 156-1087 MPa and 7.9-587 GPa; the bending strength reaches 123-756 MPa; the in-plane thermal conductivity of the composite material reaches 13-542W/(m.K), and the out-of-plane thermal conductivity of the composite material reaches 8.5-90W/(m.K). Part of the high-performance composite material can be used as an advanced composite material.
(2) After the discontinuous fiber reinforced poly-hexahydrotriazine heat-conducting composite material prepared by the invention is subjected to strong acid degradation treatment, the non-continuous fiber and the heat-conducting filler can be recycled without damage, and the recovery rate reaches more than 93%; the aromatic amine which is the main raw material of the matrix can be recycled, and the recovery rate reaches more than 94%.
Detailed Description
The present invention will be further described with reference to the following examples, but the present invention is not limited to the following examples.
Example 1
Preparing 180mmol of paraformaldehyde and 40ml of N-methylpyrrolidone/water mixed solvent into a suspension, stirring and reacting at 80 ℃ for 30 minutes for depolymerization, and cooling to room temperature to obtain a formaldehyde reaction solution. Subjecting 90mmol of p-aminobenzoic acid p-aminophenyl ester
The resulting mixture was dissolved in 120ml of N-methylpyrrolidone to obtain an aromatic amine reaction solution. And (3) uniformly mixing the formaldehyde reaction solution and the aromatic amine reaction solution (the volume content of water in the mixed solvent of the final reaction system is 20%), stirring and reacting at 50 ℃ for 10 minutes to perform prepolymerization, thereby obtaining a prepolymer solution. Mixing heat conductive graphite fiber (Japanese graphite fiber) with length of 25mmCompany, the thermal conductivity is about 900W/(m.K)) and heat conducting filler boron nitride particles are added into a prepolymer solution, stirred uniformly at high speed by a stirrer, added with 300ml of water for precipitation, filtered, put into an oven for drying at 120 ℃ for 1 hour, removed of the solvent, and naturally cooled to room temperature to obtain the prepreg. And (3) putting a certain amount of prepreg into the die according to the size of the die and the required thickness of the material, putting the die into a hot press, and closing the die. Heating to 140 ℃ at the speed of 10 ℃/min, pressurizing to 3MPa, keeping the temperature for 0.5 hour, exhausting for 1 time, keeping the pressure unchanged, heating to 230 ℃ at the speed of 10 ℃/min, keeping the temperature for 2 hours, cooling to below 100 ℃ at the speed of 5 ℃/min, and demolding to obtain the composite material. The composite material comprises 60% of fiber by mass, 15% of heat-conducting filler by mass and 25% of resin by mass. The tensile strength and modulus of the composite material are 1087.4MPa and 586.9GPa respectively (the tensile property is determined according to the ASTM D638-14 standard); the composite material has a flexural strength of 756.4MPa (flexural properties determined according to ASTM D790-10); the composite material had an in-plane thermal conductivity of 541.9W/(m.K) and an out-of-plane thermal conductivity of 35.4W/(m.K) (measured according to ISO22007-2 standard). Soaking each gram of composite material in 30ml of tetrahydrofuran/hydrochloric acid solution with the concentration of 0.5mol/L for 24 hours at room temperature, taking out fibers from the acid solution, cleaning the fibers with the tetrahydrofuran/hydrochloric acid solution, water, saturated sodium carbonate solution and water, drying the fibers, and recovering to obtain the carbon fiber cloth, wherein the recovery rate reaches 99.7%. Further filtering or centrifugally separating the degradation acid solution, washing the degradation acid solution with tetrahydrofuran hydrochloric acid solution, water, saturated sodium carbonate solution and water, drying the degradation acid solution, and recovering to obtain the heat-conducting filler, wherein the recovery rate reaches 98.5%; and finally, neutralizing the degradation acid solution by using a saturated sodium carbonate solution, precipitating, filtering, washing with water, and drying to obtain the aromatic amine, wherein the recovery rate reaches 96.3%.
Example 2
Preparing 120mmol of paraformaldehyde and 30ml of N-methylpyrrolidone/water mixed solvent into a suspension, stirring and reacting at 80 ℃ for 15 minutes for depolymerization, and cooling to room temperature to obtain a formaldehyde reaction solution. 60mmol of 4,4' -diaminobenzanilide
Is dissolved in80ml of N-methylpyrrolidone, to obtain an aromatic amine reaction solution. And (3) uniformly mixing the formaldehyde reaction solution and the aromatic amine reaction solution (the volume content of water in the mixed solvent of the final reaction system is 20%), stirring and reacting at 60 ℃ for 10 minutes to perform prepolymerization, thereby obtaining a prepolymer solution. Adding 500ml ethanol for precipitation, filtering, placing in an oven for drying at 100 ℃ for 2 hours, removing the solvent, and naturally cooling to room temperature to obtain powdery prepolymer. A heat conductive graphite fiber (about 900W/(m.K) in thermal conductivity, Japan graphite fiber Co., Ltd.) having a length of 3mm, a heat conductive filler (silicon nitride, graphene, mass ratio 3:1) and a powdery prepolymer were kneaded in a kneader at 100 ℃ for 1 hour to obtain a prepreg. And (3) putting a certain amount of prepreg into the die according to the size of the die and the required thickness of the material, putting the die into a hot press, and closing the die. Heating to 160 deg.C at a rate of 15 deg.C/min, pressurizing to 6MPa, holding for 0.5 hr, exhausting for 2 times, holding pressure, heating to 190 deg.C at a rate of 1 deg.C/min, holding for 3 hr, cooling to below 100 deg.C at a rate of 3 deg.C/min, and demolding. The composite material comprises 50% of fiber by mass, 20% of heat-conducting filler by mass and 30% of resin by mass. The tensile strength and the modulus of the composite material are 787.1MPa and 384.6GPa respectively; the bending strength of the composite material is 452.8 MPa; the composite material has the in-plane thermal conductivity of 381.3W/(m.K) and the out-of-plane thermal conductivity of 89.7W/(m.K). Soaking each gram of composite material in 30ml of tetrahydrofuran/hydrochloric acid solution with the concentration of 0.5mol/L for 24 hours at room temperature, taking out fibers from the acid solution, cleaning the fibers with the tetrahydrofuran/hydrochloric acid solution, water, saturated sodium carbonate solution and water, drying the fibers, and recovering to obtain the carbon fiber cloth, wherein the recovery rate reaches 99.2%. Further filtering or centrifugally separating the degradation acid solution, washing the degradation acid solution with tetrahydrofuran hydrochloric acid solution, water, saturated sodium carbonate solution and water, drying the degradation acid solution, and recovering to obtain the heat-conducting filler, wherein the recovery rate reaches 93.8%; and finally, neutralizing the degradation acid solution by using a saturated sodium carbonate solution, precipitating, filtering, washing with water and drying to obtain the aromatic amine, wherein the recovery rate reaches 95.5%.
Example 3
Preparing 180mmol paraformaldehyde and 30ml N-methyl pyrrolidone/tetrahydrofuran/water mixed solvent into suspension, stirring at 85 deg.C for 30 min for depolymerization, and coolingAnd (4) cooling to room temperature to obtain a formaldehyde reaction solution. 30mmol of p-aminobenzoic acid p-aminophenyl ester
And 60mmol of 4,4' -diaminobenzanilide
The resulting mixture was dissolved in 150ml of N-methylpyrrolidone/tetrahydrofuran to obtain an aromatic amine reaction solution. And (2) uniformly mixing the formaldehyde reaction solution and the aromatic amine reaction solution (the volume content of water in the mixed solvent of the final reaction system is 10%, and the volume ratio of the N-methyl pyrrolidone to the tetrahydrofuran is 1:1), and stirring and reacting at 50 ℃ for 15 minutes to perform prepolymerization to obtain a prepolymer solution. Adding carbon fiber (T300) with the length of 10mm and heat-conducting filler (silicon nitride and copper particles in a mass ratio of 1:1) into the prepolymer solution, uniformly stirring at a high speed by using a stirrer, adding 400ml of diethyl ether for precipitation, filtering, putting into an oven, drying at 100 ℃ for 5 hours, removing the solvent, and naturally cooling to room temperature to obtain the prepreg. And (3) putting a certain amount of prepreg into the die according to the size of the die and the required thickness of the material, putting the die into a hot press, and closing the die. Heating to 180 ℃ at the speed of 10 ℃/min, pressurizing to 5MPa, keeping the temperature for 0.5 hour, exhausting for 1 time, keeping the pressure unchanged, heating to 250 ℃ at the speed of 5 ℃/min, keeping the temperature for 1 hour, cooling to below 100 ℃ at the speed of 5 ℃/min, and demolding to obtain the composite material. The composite material comprises 10% of fiber by mass, 60% of heat-conducting filler by mass and 30% of resin by mass. The tensile strength and the modulus of the composite material are 236.9MPa and 15.6GPa respectively; the bending strength of the composite material is 157.3 MPa; the composite material has an in-plane thermal conductivity of 65.8W/(mK) and an out-of-plane thermal conductivity of 47.3W/(mK). Soaking each gram of composite material in 30ml of tetrahydrofuran/hydrochloric acid solution with the concentration of 0.5mol/L for 24 hours at room temperature, taking out fibers from the acid solution, cleaning the fibers with the tetrahydrofuran/hydrochloric acid solution, water, saturated sodium carbonate solution and water, drying the fibers, and recovering to obtain the carbon fiber cloth, wherein the recovery rate reaches 99.5%. Further filtering or centrifuging the degradation acid solution, washing with tetrahydrofuran hydrochloric acid solution, water, saturated sodium carbonate solution, and water, drying, and recovering to obtain heat conducting materialThe recovery rate of the filler reaches 96.9 percent; and finally, neutralizing the degradation acid solution by using a saturated sodium carbonate solution, precipitating, filtering, washing with water, and drying to obtain the aromatic amine, wherein the recovery rate reaches 95.3%.
Example 4
Preparing 180mmol of paraformaldehyde and 50ml of dimethyl sulfoxide/water mixed solvent into a suspension, stirring and reacting at 75 ℃ for 50 minutes for depolymerization, and cooling to room temperature to obtain a formaldehyde reaction solution. 30mmol of bis (p-aminobenzoic acid) -1, 5-naphthalene diester
30mmol of 4- (4-aminophenoxy) phenyl-4-aminobenzamide
And 30mmol of N, N' -bis (4-aminophenyl) terephthalamide
Dissolved in 160ml of N-methylpyrrolidone/dimethyl sulfoxide/hexamethylphosphoramide to obtain an aromatic amine reaction solution. And (3) uniformly mixing the formaldehyde reaction solution and the aromatic amine reaction solution (the volume content of water in the mixed solvent of the final reaction system is 15%, and the volume ratio of N-methylpyrrolidone, dimethyl sulfoxide and hexamethylphosphoramide is 2:1:1), and stirring and reacting at 30 ℃ for 60 minutes to perform prepolymerization to obtain a prepolymer solution. Adding 2 mm-long polybenzoxazole chopped fiber (Sylon HM) and heat-conducting filler (silicon nitride and diamond in a mass ratio of 5:1) into the prepolymer solution, uniformly stirring at high speed by using a stirrer, adding 600ml of petroleum ether for precipitation, filtering, putting into an oven, drying at 120 ℃ for 3 hours, removing the solvent, and naturally cooling to room temperature to obtain the prepreg. And (3) putting a certain amount of prepreg into the die according to the size of the die and the required thickness of the material, putting the die into a hot press, and closing the die. Heating to 180 deg.C at a rate of 5 deg.C/min, pressurizing to 4MPa, holding for 1 hr, exhausting for 1 time, keeping the pressure unchanged, heating to 220 deg.C at a rate of 3 deg.C/min, holding for 2 hr, cooling to below 100 deg.C at a rate of 5 deg.C/min, and demolding. The composite material comprises 20% of fiber by mass and the heat-conducting filler by mass55 percent and 25 percent of resin by mass percentage. The tensile strength and the modulus of the composite material are 178.8MPa and 10.7GPa respectively; the bending strength of the composite material is 138.9 MPa; the composite material has an in-plane thermal conductivity of 13.1W/(mK) and an out-of-plane thermal conductivity of 8.5W/(mK). Soaking each gram of composite material in 30ml of tetrahydrofuran/hydrochloric acid solution with the concentration of 0.5mol/L for 24 hours at room temperature, taking out fibers from the acid solution, cleaning the fibers with the tetrahydrofuran/hydrochloric acid solution, water, saturated sodium carbonate solution and water, drying the fibers, and recovering to obtain the carbon fiber cloth, wherein the recovery rate reaches 99.9%. Further filtering or centrifugally separating the degradation acid solution, washing the degradation acid solution with tetrahydrofuran hydrochloric acid solution, water, saturated sodium carbonate solution and water, drying the degradation acid solution, and recovering to obtain the heat-conducting filler, wherein the recovery rate reaches 93.7%; and finally, neutralizing the degradation acid solution by using a saturated sodium carbonate solution, precipitating, filtering, washing with water, and drying to obtain the aromatic amine, wherein the recovery rate reaches 94.5%.
Example 5
Preparing 180mmol of paraformaldehyde and 30ml of N-methylpyrrolidone/water mixed solvent into a suspension, stirring and reacting at 90 ℃ for 30 minutes for depolymerization, and cooling to room temperature to obtain a formaldehyde reaction solution. 60mmol of 4,4' -diaminobenzanilide
And 30mmol of 2, 2-bis [4- (4-aminophenoxy) phenyl]Propane
The resulting mixture was dissolved in 90ml of N-methylpyrrolidone to obtain an aromatic amine reaction solution. And (3) uniformly mixing the formaldehyde reaction solution and the aromatic amine reaction solution (the volume content of water in the mixed solvent of the final reaction system is 5%), stirring and reacting at 60 ℃ for 20 minutes to perform prepolymerization, thereby obtaining a prepolymer solution. Adding 1000ml of water for precipitation, filtering, putting into an oven, drying for 2 hours at 130 ℃, removing the solvent, and naturally cooling to room temperature to obtain powdery prepolymer. And (3) dispersing long aramid fiber (914) with the length of 20mm, graphite fiber powder, heat-conducting filler boron nitride and powdery prepolymer in a high-speed dispersion machine at the temperature of 80 ℃ for 0.5 hour to obtain the prepreg. A certain amount of prepreg is put into the mould according to the size of the mould and the required thickness of the materialAnd (5) placing the die in a hot press, and closing the die. Heating to 160 ℃ at the speed of 10 ℃/min, pressurizing to 3MPa, preserving heat for 1 hour, exhausting for 2 times, keeping the pressure unchanged, heating to 220 ℃ at the speed of 8 ℃/min, preserving heat for 2 hours, cooling to below 100 ℃ at the speed of 5 ℃/min, and demolding to obtain the composite material. The composite material comprises 10 mass percent of aramid fiber, 50 mass percent of graphite fiber powder (Japan graphite fiber company, the thermal conductivity is about 900W/(m.K)), 20 mass percent of boron nitride and 20 mass percent of resin. The tensile strength and the modulus of the composite material are respectively 156.4MPa and 7.9 GPa; the bending strength of the composite material is 125.8 Mpa; the composite material has the in-plane thermal conductivity of 34.8W/(mK) and the out-of-plane thermal conductivity of 21.3W/(mK). Soaking each gram of composite material in 30ml of tetrahydrofuran/hydrochloric acid solution with the concentration of 0.5mol/L for 24 hours at room temperature, taking out fibers from the acid solution, cleaning the fibers with the tetrahydrofuran/hydrochloric acid solution, water, saturated sodium carbonate solution and water, drying the fibers, and recovering to obtain the carbon fiber cloth, wherein the recovery rate reaches 99.7%. Further filtering or centrifugally separating the degradation acid solution, washing the degradation acid solution with tetrahydrofuran hydrochloric acid solution, water, saturated sodium carbonate solution and water, drying the degradation acid solution, and recovering to obtain the heat-conducting filler, wherein the recovery rate reaches 96.1%; and finally, neutralizing the degradation acid solution by using a saturated sodium carbonate solution, precipitating, filtering, washing with water, and drying to obtain the aromatic amine, wherein the recovery rate reaches 94.8%.
Example 6
The present embodiment is different from embodiment 1 in that: the aromatic amine is 4,4' -diaminodiphenylmethane
The test results of the prepared composite material are as follows: the tensile strength and the modulus are 895.1MPa and 516.3GPa respectively; the bending strength of the composite material is 663.7 Mpa; the in-plane thermal conductivity was 353.7W/(mK), and the out-of-plane thermal conductivity was 17.5W/(mK).
Example 7
The present embodiment is different from embodiment 2 in that: the aromatic amine is 2, 2-bis [4- (4-aminophenoxy) phenyl]Propane
The test results of the prepared composite material are as follows: the tensile strength and the modulus are 752.4MPa and 375.1GPa respectively; the bending strength of the composite material is 447.1 MPa; the in-plane thermal conductivity was 251.2W/(mK), and the out-of-plane thermal conductivity was 56.9W/(mK).
Example 8
The present embodiment is different from embodiment 3 in that: the aromatic amine is 4,4' -diamino diphenyl sulfone
The test results of the prepared composite material are as follows: the tensile strength and the modulus are respectively 212.8MPa and 15.1 GPa; the bending strength of the composite material is 143.6 Mpa; the in-plane thermal conductivity was 42.3W/(mK), and the out-of-plane thermal conductivity was 21.4W/(mK).
Example 9
This embodiment is different from embodiment 4 in that: the aromatic amine is 4,4' -diaminodiphenyl ether
The test results of the prepared composite material are as follows: the tensile strength and the modulus are 159.1MPa and 9.2GPa respectively; the bending strength of the composite material is 132.5 Mpa; the in-plane thermal conductivity was 8.6W/(mK), and the out-of-plane thermal conductivity was 4.7W/(mK).
Example 10
This embodiment is different from embodiment 5 in that: the aromatic amine is 60mmol of 4,4' -diaminodiphenyl ether
And 30mmol of 2, 2-bis [4- (4-aminophenoxy) phenyl]Propane
The test results of the prepared composite material are as follows: the tensile strength and the modulus are 147.9MPa and 7.3GPa respectively; the bending strength of the composite material is 122.8 MPa; the in-plane thermal conductivity was 17.6W/(mK), and the out-of-plane thermal conductivity was 11.7W/(mK).
TABLE 1 thermal conductivity results for discontinuous fiber reinforced polyhexahydrotriazine composites
| EXAMPLES/COMPARATIVE EXAMPLES | In-plane thermal conductivity (W/(m.K)) | Out-of-plane thermal conductivity (W/(m.K)) |
| Example 1 | 541.9 | 35.4 |
| Example 6 | 353.7 | 17.5 |
| Example 2 | 381.3 | 89.7 |
| Example 7 | 251.2 | 56.9 |
| Example 3 | 65.8 | 47.3 |
| Example 8 | 42.3 | 21.4 |
| Example 4 | 13.1 | 8.5 |
| Example 9 | 8.6 | 4.7 |
| Example 5 | 34.8 | 21.3 |
| Example 10 | 17.6 | 11.7 |
The results in table 1 show that the discontinuous fiber reinforced poly-hexahydrotriazine resin-based composite material prepared by using the aromatic diamine containing an aromatic amide or aromatic ester structure as a resin raw material has more excellent heat-conducting property under the same conditions.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (10)
1. A preparation method of a discontinuous fiber reinforced poly-hexahydrotriazine resin-based heat-conducting composite material is characterized by comprising the following steps:
(1) uniformly dissolving formaldehyde and aromatic amine in a water/aprotic solvent mixed solution, stirring the obtained reaction solution at 30-100 ℃ to react for 5-120 minutes to perform prepolymerization to obtain a prepolymer solution, uniformly mixing a heat-conducting filler and discontinuous fibers in the prepolymer solution, adding a solvent to perform precipitation, and filtering and drying to obtain a prepreg A;
or pre-polymerizing formaldehyde and aromatic amine in a water/aprotic solvent mixed solution, adding a solvent for precipitation, drying to obtain a powdery prepolymer, and uniformly mixing the powdery prepolymer, a heat-conducting filler and discontinuous fibers to obtain a prepreg B;
(2) and (3) carrying out hot-pressing curing molding on the prepreg A or B to obtain the composite material.
2. The preparation method according to claim 1, wherein the hot-press curing molding process comprises the following steps: heating to 140-180 ℃ at a heating rate of 5-20 ℃/min, preserving heat for 0.5-1 hour, pressurizing to 0.5-7 MPa, exhausting for 1-2 times, keeping the pressure unchanged, heating to 190-250 ℃ at a heating rate of 1-10 ℃/min, preserving heat for 0.5-3 hours, cooling to below 100 ℃ at a heating rate of 1-5 ℃/min, and demolding.
3. The method according to claim 2, wherein the discontinuous fiber is any one or more of a long fiber having a length of 10 to 25mm, a short fiber having a length of 2 to 3mm, and a powder fiber having a length of less than 2 mm; the fiber type comprises one or more than two of carbon fiber, graphite fiber, glass fiber, aramid fiber, quartz fiber, basalt fiber, ceramic fiber, polybenzoxazole fiber and polybenzimidazole fiber.
4. The method according to claim 3, wherein the thermally conductive filler is one or more selected from the group consisting of alumina particles, aluminum nitride particles, silicon nitride particles, boron nitride particles, silicon carbide particles, magnesium oxide particles, zinc oxide particles, silica particles, barium titanate particles, aluminum hydroxide particles, titanium dioxide particles, gold particles, silver particles, copper particles, aluminum particles, iron particles, zinc particles, nickel particles, carbon nanofibers, diamond, graphite, carbon black, carbon nanotubes, graphene, and graphdine.
5. The method according to claim 1, 2, 3 or 4, wherein the aromatic amine is an aromatic diamine having at least one aromatic amide or aromatic ester structure; the molar ratio of the formaldehyde to the aromatic amine is 2:1, the aromatic amine is one or more than two of the following structures:
6. the method according to claim 5, wherein the aprotic solvent is one or more of N-methylpyrrolidone, dimethylformamide, N-dimethylacetamide, dimethylsulfoxide, tetrahydrofuran, 2, 5-dimethylfuran, and hexamethylphosphoramide; the volume content of water in the mixed solvent is 0.5-60%; the solvent of the precipitation prepolymer is one or more than two of water, ethanol, ether, acetone and petroleum ether.
7. The preparation method of claim 5, wherein the content of the poly-hexahydrotriazine in the composite material is 10-95% by mass, the content of the discontinuous fiber in the composite material is 4.5-75% by mass, and the content of the heat-conducting filler in the composite material is 0.5-85% by mass.
8. The discontinuous fiber reinforced poly-hexahydrotriazine resin-based heat-conducting composite material prepared by the method of any one of claims 1 to 7.
9. The recycling method of the composite material of claim 8, wherein the composite material is soaked in a mixed solution of a strong acid/aprotic solvent, fibers are filtered from the degraded acid solution through a screen, and the fibers are recovered by drying after being washed with water, an alkali solution and water; further filtering the degraded acid solution by using quantitative filter paper, washing with water, an alkali solution and water, drying, and recovering to obtain the heat-conducting filler; and finally, neutralizing the degraded acid solution with an alkali solution, precipitating, filtering, washing with water, and drying to obtain the aromatic amine.
10. The recycling method of the composite material according to claim 9, wherein the strong acid is sulfuric acid or hydrochloric acid, and the alkali solution is a saturated solution of sodium carbonate or sodium bicarbonate; the using amount of the strong acid/aprotic solvent mixed solution is 5-30 ml per gram of the composite material, the concentration of the strong acid is 0.5-12 mol/L, the aprotic solvent is one or more than two of N-methylpyrrolidone, dimethylformamide, N-dimethylacetamide, dimethyl sulfoxide, tetrahydrofuran, 2, 5-dimethylfuran and hexamethylphosphoramide, and the soaking temperature is 20-95 ℃ for 0.5-24 hours.
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| US20160039976A1 (en) * | 2014-08-05 | 2016-02-11 | International Business Machines Corporation | High-performance, filler-reinforced, recyclable composite materials |
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| CN105400132A (en) * | 2015-12-14 | 2016-03-16 | 华南理工大学 | Non-continuous fiber-reinforced thermosetting-resin-based composite material and preparation method therefor |
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