Preparation method of graphene oxide modified phthalonitrile resin

Abstract

The application relates to a preparation method of graphene oxide modified phthalonitrile resin, and belongs to the technical field of high-temperature-resistant resin toughening and reinforcing. The preparation method of the graphene oxide modified phthalonitrile resin comprises the following steps: performing cyanogen modification on the surface of graphene oxide by using amino-phthalonitrile; performing mechanical blending and dispersion of the modified graphene and phthalonitrile resin; finally, heating and curing the resin to obtain a modified phthalonitrile resin curing product or prepare a fiber-reinforced phthalonitrile resin-based composite material. The cyanogen modification of the graphene oxide helps to improve the compatibility of the graphene oxide and the phthalonitrile resin, improve the dispersion effect and the toughening and reinforcing effect of the graphene oxide in the phthalonitrile resin, and also improve the mechanical properties of the fiber-reinforced phthalonitrile resin-based composite material.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of graphene oxide modified phthalonitrile resin and its preparation method, belong to high-temperature-resistant resin toughening and reinforcing technical field. BACKGROUND

[0002] Phthalonitrile is a high-temperature-resistant thermosetting resin system, it is connected with carbon-nitrogen triple bond (—C≡N) on benzene ring as active cyano group, and the adjacent cyano group is absorbed into electron group when crosslinking and curing, and the addition reaction is formed with the conjugate stable effect of phthalocyanine ring, triazine ring and other aromatic heterocycle, and its glass transition temperature is greater than 450 DEG C. Phthalonitrile resin is widely concerned in aerospace field and other fields due to its advantages such as no small molecule release during curing, high heat resistance and stability, and is used for high-temperature-resistant bearing structure and heat-resistant structure. Its heat resistance is higher than that of bismaleimide and benzoxazine resin, the processing property is better than that of polyimide resin, and the cost is moderate, and it has great application prospect in advanced composite material field. However, due to the high crosslinking density and strong molecular chain rigidity of phthalonitrile resin, the toughness is poor, and the mechanical properties of resin and composite material are low, which seriously hinders the further development and application of phthalonitrile resin. Using traditional toughening method of thermosetting resin, such as molecular chain grafting flexible chain segment and blending with thermoplastic resin, can greatly reduce the heat resistance of phthalonitrile resin. Graphene oxide (GO) has excellent heat resistance, mechanical properties and surface activity, and can absorb energy through interfacial action and bridging action in resin matrix to improve the toughness and strength of resin, and does not reduce the heat resistance of resin. However, with the increase of graphene oxide content, the toughening and reinforcing effect is obviously reduced due to agglomeration, and the performance fluctuates greatly. In addition, there is no obvious chemical bonding group between graphene oxide and phthalonitrile resin, and the compatibility between them is poor, which further reduces the dispersion of graphene oxide in resin and the toughening and reinforcing effect of resin after curing. Therefore, how to improve the compatibility of graphene oxide and phthalonitrile resin becomes the key to the modification of phthalonitrile resin. The present application realizes the preparation of cyano graphene with high yield and low cost through a simple and efficient preparation method, improves the compatibility of graphene and phthalonitrile resin, and can significantly improve the mechanical properties and heat resistance of phthalonitrile resin and fiber reinforced composite material. SUMMARY

[0003] The purpose of the present application is to provide a simple and efficient cyano modification method of graphene oxide, to improve the compatibility with phthalonitrile resin, and to improve the dispersion effect and toughening and reinforcing effect of graphene oxide in phthalonitrile resin.

[0004] 1. The present application provides a preparation method of graphene oxide modified phthalonitrile resin, comprising the following steps:

[0005] (1) The surface acyl chloride modification of graphene oxide (GO) is carried out by using thionyl chloride. The acyl chloride graphene (GO-COCl) powder is obtained after drying thionyl chloride.

[0006] (2) The surface amidation modification of acyl chloride graphene (GO-COCl) is carried out by using amino phthalonitrile (APN). The unreacted APN is removed by washing and centrifuging with N,N-dimethylformamide (DMF). The cyanated graphene (GO-APN) powder is obtained after vacuum drying.

[0007] (3) The cyanated graphene (GO-APN) powder is mechanically blended with phthalonitrile resin, including mechanical stirring and three-roll grinding.

[0008] (4) The resin mixture obtained in (3) is heated and cured to obtain a cured product or prepare a fiber-reinforced composite material.

[0009] Preferably, the concentration of graphene oxide in thionyl chloride in step (1) is 0.00125-0.002 g / ml, the reaction temperature is 70-75℃, and the reaction time is 24 h.

[0010] Preferably, the concentration of acyl chloride graphene GO-COCl powder in DMF solution in step (2) is 0.0005-0.001 g / ml, the mass ratio of amino phthalonitrile APN to GO-COCl is 3:1-5:1, the reaction temperature is 80-100℃, and the reaction time is 8-10 h.

[0011] Preferably, the addition amount of GO-APN powder in phthalonitrile resin in step (3) is 0.1wt%-0.5wt%, mechanical stirring is carried out at 140-150℃, the stirring rate is 1000-2000 r / min, and the stirring time is 0.5-1 h. Subsequently, the resin mixture is subjected to one-pass three-roll grinding at a roller gap of 20-10 μm, one-pass three-roll grinding at a roller gap of 10-5 μm, and one-pass three-roll grinding at a roller gap of 5-3 μm after heating the three-roll temperature to the resin softening point temperature.

[0012] Preferably, the heating rate of the oven in step (4) is 1-10℃ / min, and the curing is carried out at 200℃-380℃ for 5-20 h, followed by natural cooling to room temperature.

[0013] Preferably, carbon fiber, quartz fiber, high-silica fiber, glass fiber, basalt fiber, aramid fiber, etc. can be used to prepare fiber-reinforced phthalonitrile resin-based composite materials in step (4), and one of the following processes can be used: autoclave process, molding process, liquid molding process, and winding process.

[0014] The preparation method of the graphene oxide modified phthalonitrile resin has the advantages of simple process, high yield, good compatibility of the graphene oxide and the phthalonitrile resin, and excellent heat resistance and toughness and strength of the resin.(1) The graphene oxide is surface modified by using amino phthalonitrile (APN), and then the unreacted APN is removed by washing and centrifugation using N,N-dimethylformamide (DMF), the unreacted APN is removed by washing and centrifugation using N,N-dimethylformamide (DMF), and the cyanated graphene GO-APN powder is obtained after vacuum drying, which has the characteristics of high yield and low cost.(2) The cyanated graphene GO-APN powder is mechanically blended with the phthalonitrile resin, and finally cured into a resin pouring body, which is easy to operate and has a simple process.(3) The graphene oxide is surface modified, the acyl chloride bond is grafted on the surface of the oxygen-containing active group, and then the acyl chloride bond is further amidated to prepare the graphene GO-APN powder grafted with phthalonitrile by the amide bond, the surface of the graphene GO-APN powder is provided with the cyano grafting group, and the compatibility between the graphene oxide and the resin is improved. The graphene oxide modified phthalonitrile resin and the fiber reinforced composite material prepared by the method have excellent mechanical properties and high heat resistance. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The basic reaction formula of the present application. DETAILED DESCRIPTION

[0016] The technical solutions of the present application are further described in combination with the specific embodiments.

[0017] Example 1

[0018] The preparation method of the graphene oxide modified phthalonitrile resin of the present embodiment comprises the following steps:

[0019] (1) 1 part by weight of GO powder and 80 parts by volume of thionyl chloride are added to a three-necked flask, nitrogen protection is performed, the temperature is increased to 70 DEG C, and magnetic stirring is performed for 24 hours, and then 100 DEG C drying is performed for 24 hours to obtain acyl chloride GO-COCl powder.

[0020] (2) 1 part by weight of the acyl chloride GO-COCl powder obtained in (1) and 200 parts by volume of DMF solvent are added to a three-necked flask, 3 parts by weight of amino phthalonitrile APN is added at 80 DEG C, and after 8 hours of reaction, the obtained solution is repeatedly washed with DMF solvent and centrifuged for several times, and then washed until the solution is clear, and finally vacuum dried at 80 DEG C for 24 hours to obtain GO-APN powder.

[0021] (3) 1 part by weight of GO-APN powder obtained in (2) was mechanically stirred and dispersed with 1000 parts by weight of 4,4-(phenoxy)phthalonitrile resin at 150°C, the stirring rate was 1500 r / min, and the stirring time was 1 h. After heating to the resin softening point temperature, the resin mixture was once three-roll milled according to a roll gap of 20-10 μm, once three-roll milled according to a roll gap of 10-5 μm, and once three-roll milled according to a roll gap of 5-3 μm.

[0022] (4) The phthalonitrile resin mixture obtained in (3) (denoted as 0.1%wt GO-APN) was heated and cured, and after curing at 375°C / 5h at a temperature increasing rate of 1°C / min, it was naturally cooled to room temperature.

[0023] Example 2

[0024] The preparation method of the graphene oxide modified phthalonitrile resin of the present example comprises the following steps:

[0025] (1) 1 part by weight of GO powder, 80 parts by volume of thionyl chloride were added to a three-necked flask, protected by nitrogen, and magnetically stirred at 70°C for 24 h, and then dried at 100°C for 24 h to obtain acyl chloride GO-COCl powder.

[0026] (2) 1 part by weight of acyl chloride GO-COCl powder obtained in (1) and 200 parts by volume of DMF solvent were added to a three-necked flask, and 4 parts by weight of amino phthalonitrile APN was added at 80°C, and the obtained solution was washed to a clear solution by repeatedly adding DMF solvent and centrifuging several times, and finally dried at 80°C under vacuum for 24 h to obtain GO-APN powder.

[0027] (3) 1 part by weight of GO-APN powder obtained in (2) was mechanically stirred and dispersed with 333 parts by weight of 4,4-(phenoxy)phthalonitrile resin at 150°C, the stirring rate was 1500 r / min, and the stirring time was 1 h. After heating to the resin softening point temperature, the resin mixture was once three-roll milled according to a roll gap of 20-10 μm, once three-roll milled according to a roll gap of 10-5 μm, and once three-roll milled according to a roll gap of 5-3 μm.

[0028] (4) The phthalonitrile resin mixture obtained in (3) (denoted as 0.3%wt GO-APN) was heated and cured, and after curing at 375°C / 5h at a temperature increasing rate of 1°C / min, it was naturally cooled to room temperature.

[0029] Example 3

[0030] The preparation method of the graphene oxide functionalized modified phthalonitrile resin of the embodiment comprises the following steps:

[0031] (1) 1 part by weight of GO powder, 80 parts by volume of thionyl chloride were added to a three-necked flask, protected by nitrogen, and heated to 70°C for magnetic stirring reaction for 24h, and then dried at 100°C for 24h to obtain acyl chloride GO-COCl powder.

[0032] (2) 1 part by weight of acyl chloride GO-COCl powder obtained in (1) and 200 parts by volume of DMF solvent were added to a three-necked flask, and 4 parts by weight of amino phthalonitrile APN was added at 80°C, and the obtained solution was washed to clear solution after repeated addition of DMF solvent and several times of centrifugation, and finally dried at 80°C under vacuum for 24h to obtain GO-APN powder.

[0033] (3) 1 part by weight of GO-APN powder obtained in (2) and 333 parts by weight of 4,4-(phenoxy) phthalonitrile resin were mechanically stirred and dispersed at 150°C, with a stirring rate of 1500r / min and a stirring time of 1h. After heating to the resin softening point temperature, the resin mixture was once three-roll milled with a roll gap of 20-10μm, once three-roll milled with a roll gap of 10-5μm, and once three-roll milled with a roll gap of 5-3μm.

[0034] (4) The phthalonitrile resin mixture obtained in (3) (marked as 0.3%wt GO-APN) was prepared into a prepreg with T700 grade carbon fiber, and a composite material was prepared by a molding process, and cured at 200°C / 4h, 315 / 5h, and 375°C / 5h.

[0035] Comparative Example 1

[0036] The preparation method of the graphene oxide modified phthalonitrile resin of the comparative example comprises the following steps:

[0037] 1 part by weight of unmodified graphene oxide GO was mixed with 1000 parts by weight of 4,4-(phenoxy) phthalonitrile resin mixture in a mold, and mechanically stirred and dispersed at 150°C, with a stirring rate of 1500r / min and a stirring time of 1h. After heating to the resin softening point temperature, the resin mixture (marked as 0.1%wt GO) was once three-roll milled with a roll gap of 20-10μm, once three-roll milled with a roll gap of 10-5μm, and once three-roll milled with a roll gap of 5-3μm. After vacuum degassing, it was naturally cooled to room temperature after curing at 375°C / 5h.

[0038] Comparative Example 2

[0039] The preparation method of the graphene oxide modified phthalonitrile resin of the present comparative example comprises the following steps:

[0040] 1 part by weight of unmodified graphene oxide GO was mixed with 333 parts by weight of a 4,4-(phenoxy)phthalonitrile resin mixture in a mold, and mechanical stirring dispersion was carried out at 150°C, with a stirring rate of 1500 r / min and a stirring time of 1 h. After heating the three-roller temperature to the resin softening point temperature, the resin mixture (denoted as 0.3%wt GO) was subjected to one-pass three-roller grinding with a roller gap of 20-10 μm, one-pass three-roller grinding with a roller gap of 10-5 μm, and one-pass three-roller grinding with a roller gap of 5-3 μm, respectively. After vacuum degassing, curing was carried out at 375°C / 5h with a temperature rising rate of 5°C / min, and natural cooling to room temperature was then performed.

[0041] Comparative Example 3

[0042] The preparation method of the graphene oxide modified phthalonitrile resin of the present comparative example comprises the following steps:

[0043] A prepreg was prepared from the 4,4-(phenoxy)phthalonitrile resin and T700 grade carbon fiber, and a composite material was prepared using a molding process, and curing was carried out at 200°C / 4h, 315 / 5h, and 375°C / 5h.

[0044] Experimental Example

[0045] The 5% thermal weight loss temperature in air atmosphere, room temperature bending performance, and 400°C bending performance of the graphene oxide, cyanogenated graphene GO-APN modified 4,4-(phenoxy)phthalonitrile resin prepared in Test Example 1, Test Example 2, Comparative Example 1, and Comparative Example 2 were tested, and the corresponding test results are shown in Tables 1, 2, and 3.

[0046] Table 1 Thermal weight loss temperature of phthalonitrile resin in air atmosphere 5％ Thermal weight loss temperature comparison

[0047]

[0048] Table 2 Room temperature bending performance of unmodified GO and GO-APN modified phthalonitrile resin

[0049]

[0050] Table 3 400°C bending performance of unmodified GO and GO-APN modified phthalonitrile resin

[0051]

[0052]

[0053] Compared with the 5% thermal decomposition temperature, room temperature bending property and 400 DEG C bending property of Comparative Example 1 and Comparative Example 2, the 5% thermal decomposition temperature of the resin of Example 1 and Example 2 modified by cyanated graphene GO-APN changes little, that is, the heat resistance stability is unchanged, and the bending modulus and bending strength are improved, and the resin modified by non-cyanated graphene GO has lower heat resistance stability and mechanical property compared with the resin without graphene, which indicates the necessity of cyanation modification of graphene oxide, the surface has cyan group grafting group, which improves the dispersibility of graphene oxide and the compatibility with the resin, improves the mechanical property of the resin, and does not reduce the temperature resistance of the phthalonitrile resin.

[0054] Test Example 3 and Comparative Example 3, the room temperature and 450 DEG C mechanical properties of the prepared T700 grade carbon fiber composite material are tested, and the corresponding test results are shown in Table 4.

[0055] Table 4 Comparison of mechanical properties of T700 grade carbon fiber composite material

[0056]

[0057] Compared with Comparative Example 3, the carbon fiber composite material of Example 3 modified by cyanated graphene oxide has improved bending strength, bending modulus and interlaminar shear strength, and the mechanical property retention rate at high temperature is improved, which reflects the significant effect of cyanated graphene oxide modification.

[0058] From the above examples, the present application provides cyanation modification of graphene oxide, which improves the compatibility of graphene oxide with phthalonitrile resin, improves the dispersion effect of graphene oxide in phthalonitrile resin and the high-temperature toughening and reinforcing effect, and improves the room temperature and high-temperature mechanical properties of phthalonitrile resin-based composite material.

Claims

1. A method for preparing graphene oxide-modified phthalonitrile resin, characterized in that: Includes the following steps: Surface acyl chloride modification of graphene oxide (GO) was performed using thionyl chloride. Graphene oxide was dispersed in thionyl chloride at a concentration of 0.00125~0.002 g / ml, heated to 70~75 ℃ for 24 h, and dried at 80~100 ℃ for 24 h to remove residual thionyl chloride. After drying the thionyl chloride, acyl chloride graphene GO-COCl powder was obtained. Amination modification of esterified graphene (GO-COCl) powder was performed using aminated phthalonitrile (APN). GO-COCl was added to DMF solvent at a concentration of 0.0005–0.001 g / ml. The mass ratio of aminated phthalonitrile APN to GO-COCl was 3:1–5:

1. The aminated phthalonitrile APN was added to the DMF solution and heated to 80–100 °C for 8–10 h. The resulting solution was washed with N,N-dimethylformamide (DMF), centrifuged to remove unreacted APN, and then vacuum dried to obtain cyano-graphene (GO-APN) powder. The cyano-graphene (GO-APN) powder was mechanically blended with phthalonitrile resin, including mechanical stirring and three-roll milling. The resin mixture obtained in (3) is heated and cured to obtain a cured product or to prepare a fiber-reinforced composite material.

2. The method for preparing graphene oxide-modified phthalonitrile resin according to claim 1, characterized in that: In step (3), the amount of cyano-graphene GO-APN powder added to phthalic anhydride resin is 0.1-0.5 wt%; mechanical stirring and dispersion are carried out at 140-150℃, with a stirring rate of 1000-2000 r / min and a stirring time of 0.5-1 h. Subsequently, the three rollers were heated to the resin softening point temperature, and the mechanically stirred resin mixture was ground once with a roller gap of 10~20μm, once with a roller gap of 5~10μm, and once with a roller gap of 3~5μm.

3. The method for preparing graphene oxide-modified phthalonitrile resin according to claim 1, characterized in that: In step (4), the heating rate of the oven is 1~10℃ / min, and after curing at 200℃~380℃ / 5h~20h, it is naturally cooled to room temperature.

4. The method for preparing graphene oxide-modified phthalonitrile resin according to claim 1, characterized in that: The fibers prepared in step (4) are fiber-reinforced phthalic acid resin-based composite materials made of carbon fiber, quartz fiber, high silica fiber, glass fiber, basalt fiber, and aramid fiber. The preparation process adopts one of the following: autoclave process, molding process, liquid molding process, and winding process.

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