Aromatic nitrile resin composite curing system and preparation method thereof

Abstract

The invention belongs to the technical field of high polymer materials, and relates to an aromatic nitrile-based resin composite curing system and a preparation method, the aromatic nitrile-based resin composite curing system is obtained by curing elemental sulfur, an activator and more than one aromatic nitrile-based monomer, the activator is a nucleophilic reagent capable of enabling the elemental sulfur to be subjected to ring opening, and the aromatic nitrile-based resin composite curing system is prepared by curing more than one aromatic nitrile-based monomer. Or a reagent which reacts with elemental sulfur to generate sulfur anions, mercaptan or sulfur free radicals; or the compound is obtained by curing elemental sulfur and more than one aromatic nitrile monomer; at least one aromatic nitrile monomer contains an activating functional group. The activating agent or the activated functional group is used for enabling the elemental sulfur to be subjected to ring opening to generate active substances such as sulfur anions, mercaptan or sulfur free radicals, higher nucleophilic activity is achieved, the curing reaction of nitrile groups can be obviously promoted, and curing of the aromatic nitrile group resin is accelerated.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly to an aromatic nitrile-based resin composite curing system and a preparation method thereof. Background Art

[0002] Aromatic nitrile-based resins, represented by phthalonitrile (PN) resin, have shown important application value in cutting-edge engineering fields such as aerospace high-temperature resistant components, deep-sea equipment protective layers, and high-density integrated circuit packaging due to their outstanding thermal stability and excellent high-temperature mechanical retention.

[0003] However, the inherent chemical inertness of the nitrile functional groups in these resin systems requires high curing temperatures (typically ≥375°C) and lengthy post-curing cycles (>10 hours). This process not only results in significant energy consumption but also severely limits copolymerization compatibility with other resin matrices, resulting in a significant technical bottleneck in the design of multifunctional composites. Currently, research focuses on optimizing cure kinetics through curing agent modification strategies. Multi-component catalytic systems have been established, including transition metal complexes (such as Cu(acac)2), aromatic diamines (DDS / DDE), and phenolic hydroxyl compounds (bisphenol A). However, these existing systems still offer insufficient improvement in the reactivity of the nitrile groups (the curing exotherm is around 250°C), and the post-curing stage still requires temperatures above 350°C for more than 10 hours. Therefore, the development of novel curing systems with low-temperature, high-efficiency curing properties has become a critical challenge in this field.

[0004] Due to the strong nucleophilic properties imparted by the high polarizability of sulfur atoms, mercapto-containing curing agents are considered promising candidates for high-curing-activity systems for thermosetting resins. For example, 4-mercaptothiophenol (MPD), reported by Pu et al. [Polymer, 2022, 252, 124948], significantly lowers the curing reaction temperature of resorcinol-substituted phthalonitrile to 181°C, significantly improving curing activity compared to traditional phenolic curing agents and demonstrating excellent curing efficiency. However, the raw materials and preparation costs of these thiophenol reagents are high, and thiophenols are easily oxidized and have poor storage stability. Producing highly active curing agents at low cost remains a challenge. Summary of the Invention

[0005] The purpose of the present invention is to address the problems existing in the above-mentioned prior art and provide an aromatic nitrile resin composite curing system and a preparation method. The activator or activating group causes the sulfur element to open the ring to generate highly active curing groups such as sulfur anions, thiol groups or sulfur free radicals. The highly active curing groups can cause the aromatic nitrile monomer to undergo a rapid curing reaction at low temperatures, thereby improving the curing reaction activity.

[0006] In order to achieve the above objectives, the present invention adopts the following technical solutions to achieve them.

[0007] In the first solution provided by the present invention, the aromatic nitrile resin composite curing system is obtained by curing sulfur element, an activator and one or more aromatic nitrile monomers; the activator is a nucleophilic reagent that can open the ring of sulfur element, or a reagent that reacts with sulfur element to produce sulfur anions, thiols or sulfur free radicals.

[0008] In one embodiment, the activator is a compound containing an amine group, a phenolic hydroxyl group, an olefin group, or an alkyne group. Further, the amine group is a primary amine, a secondary amine, or a tertiary amine.

[0009] More preferably, the activator is a compound having any of the following structural formulas: (DMAM), (ODAM), (DBAM), (DEAM), (PPAM), (TOAM), (4BPOH), (2BPOH), (DIB), (DBZ).

[0010] In one possible implementation, the molar ratio of the sulfur element, the activator, and the aromatic nitrile monomer is (1-50):(1-100):100.

[0011] Furthermore, the molar ratio of the sulfur element to the aromatic nitrile monomer is preferably (10-40): 100. The molar ratio of the sulfur element to the activator is 1:8-4:1. The molar mass of the sulfur element is 256 g / mol.

[0012] In one possible implementation, the aromatic nitrile monomer is an aromatic nitrile monomer containing a group such as phthalonitrile or imidazole dinitrile. In a preferred implementation, the aromatic nitrile monomer is a compound having any of the following structural formulas: ; R is (3BOCN), (2BDDPN), (4BDDPN) or (BAPN); (PDBDCI), (PDBODCI), (PDBCDCI), (PBhDCI) or (PNDCI).

[0013] In the above scheme 1, the preparation method of the aromatic nitrile-based resin composite curing system comprises the following steps:

[0014] The sulfur element, an activator and one or more aromatic nitrile monomers are uniformly mixed in an organic solvent according to a molar ratio, and then melt prepolymerized at 130-190° C. for 0.5-5 hours; the obtained prepolymerized product is then cured at 200-380° C. to obtain an aromatic nitrile resin cured product; the organic solvent is one of acetone, ethanol or tetrahydrofuran.

[0015] In a preferred embodiment, the melt prepolymerization and curing are both carried out under a nitrogen atmosphere. After uniform blending, the resulting blend is dried before melt prepolymerization and curing. The curing temperature is preferably 200-300°C, and the curing time is 5-12 hours. Furthermore, the curing method is preferably gradient curing. After curing is complete, the resulting product is cooled to room temperature in the furnace.

[0016] In the second solution provided by the present invention, the aromatic nitrile resin composite curing system is obtained by curing sulfur element and more than one aromatic nitrile monomer; the at least one aromatic nitrile monomer contains an activated functional group; the activated functional group is 、 、 、 、 、 、 or .

[0017] In one embodiment, the molar ratio of the sulfur to the aromatic nitrile monomer is (1-50):100. Furthermore, the molar ratio of the sulfur to the aromatic nitrile monomer is preferably (10-40):100. The molar mass of the sulfur is 256 g / mol. The aromatic nitrile monomer containing the active functional group accounts for 5-100% of the total mass of the aromatic nitrile monomer.

[0018] In one implementation, the aromatic nitrile monomer containing an activated functional group is a phthalonitrile aromatic nitrile monomer containing an active functional group or an imidazole dinitrile aromatic nitrile monomer containing an active functional group.

[0019] In a preferred embodiment, the aromatic nitrile monomer containing an activated functional group is a compound having any of the following structural formulas: (DMEPN), (3HPN), (EPN), (HKPN), (PNDCI), (PDBODCI), (PBhDCI);

[0020] When the second scheme includes a cyanophenyl monomer without active functional groups, it is a compound having any of the following structural formulas: ; R is (3BOCN), (2BDDPN), (4BDDPN), or (BAPN); (PDBCDCI), (PDBDCI).

[0021] In the second technical scheme, the preparation method of the cyanophenyl resin composite curing system includes the following steps:

[0022] The elemental sulfur and the cyanophenyl monomer are uniformly blended in a molar ratio in an organic solvent, and then melt prepolymerization is carried out at 130-190°C for 0.5-5h; the obtained prepolymer product is cured at 200-380°C to obtain a cyanophenyl resin cured product; and the organic solvent is one of acetone, ethanol or tetrahydrofuran.

[0023] In a preferred implementation manner, the melt prepolymerization and curing are both carried out in a nitrogen atmosphere. After uniform blending, the obtained blending system is dried, and then melt prepolymerization and curing are carried out. The curing temperature is preferably 200-300°C, and the curing time is 5-12 hours; further, the curing mode is preferably gradient curing, and after the curing is completed, the obtained product is cooled to room temperature with the furnace.

[0024] The results show that the high-activity composite curing system containing elemental sulfur of the present application has high curing efficiency for the cyanophenyl resin, and significantly reduces the curing temperature. For example, in the system of elemental sulfur, the orthophthalonitrile monomer DMEPN with an active functional group, the thermogravimetric analysis (TGA) of pure DMEPN shows single-step weight loss, and the carbon residue rate is 0, while after adding elemental sulfur, it has obvious weight loss transition, and the carbon residue rate is 51%. And the initial curing temperature of the blending system is reduced to 170°C. At the same time, in the system of elemental sulfur and allyl-functionalized orthophthalonitrile monomer, the rheological data show that the prepolymer of the blending system has a low softening point, and at a low curing temperature (250°C), only 7h of curing, the glass transition temperature (Tg) is more than 340°C, indicating that it has good thermal mechanical properties.

[0025] Compared with the prior art, the present application has the following beneficial effects: 1) The aromatic nitrile resin composite curing system provided by the present invention contains elemental sulfur and utilizes an activator or an activated functional group to ring-open the sulfur element to generate active substances such as sulfur anions, thiols, or sulfur free radicals. These substances have higher nucleophilic activity and can significantly promote the curing reaction of the nitrile group, thereby accelerating the curing of the aromatic nitrile resin. 2) The raw materials for the aromatic nitrile resin composite curing system provided by the present invention are cheap and readily available; 3) The preparation method of the aromatic nitrile-based resin composite curing system provided by the present invention is simple and easy to control, which is conducive to application in industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 1 is the TGA spectrum of the blend system prepared in Example 1, Comparative Example 1, and Comparative Example 2; Figure 2 1 is the DSC spectra of the blend systems prepared in Example 1, Comparative Example 1, and Comparative Example 2; Figure 3 is the DMA spectrum of the aromatic nitrile resin prepared in Example 1; Figure 4 is the TGA spectrum of the blend system prepared in Example 2 and DMEPN in Comparative Example 3; Figure 5 1 is the DSC spectrum of the blend system prepared in Example 2 and the DMEPN in Comparative Example 3; Figure 6 is the DMA spectrum of the aromatic nitrile resin prepared in Example 2; Figure 7 is the TGA spectrum of the blend system prepared in Example 3 and 3HPN in Comparative Example 4; Figure 8 is the DSC spectrum of the blend system prepared in Example 3 and 3HPN in Comparative Example 4; Figure 9 is the DMA spectrum of the aromatic nitrile resin prepared in Example 3; Figure 10 1 is a TGA spectrum of the blend system prepared in Example 4, 3HPN in Comparative Example 5, and sulfur in Comparative Example 6; Figure 11 is the DSC spectrum of the blend system prepared in Example 4 and 3HPN in Comparative Example 4; Figure 12 is the DMA spectrum of the aromatic nitrile resin prepared in Example 4; Figure 13 5 is the TGA spectrum of the blend system prepared in Example 5, Comparative Example 7, and Comparative Example 8; Figure 14 5 is the DSC spectrum of the blend system prepared in Example 5, Comparative Example 7, and Comparative Example 8; Figure 15 is the DMA spectrum of the aromatic nitrile resin prepared in Example 5; Figure 16 This is the DMA spectrum of the aromatic nitrile resin prepared in Example 6. DETAILED DESCRIPTION

[0027] The following will clearly and completely describe the technical solutions of various embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0028] Example 1

[0029] The aromatic nitrile-based resin composite curing system provided in this embodiment includes 0.67 mmol of elemental sulfur (S8), 1.33 mmol of p-phenylenediamine (DMAM, activator), and 6 mmol of 2BDDPN (as shown in structural formula I).

[0030] Structural Formula I: , R is ;

[0031] Sulfur, p-phenylenediamine and 2BDDPN were ground and blended with the aid of 8 ml of acetone as a solvent, and then rotary evaporated and dried at 40°C for 12 h to obtain a three-component blend system (2BDDPN-S8-DMAM).

[0032] Investigation of curing kinetics of blending system:

[0033] (1) Take 6 mg of the three-component blend system and put it into a crucible. In a nitrogen atmosphere, heat it from 30°C to 800°C at 10°C / min for TGA test. The test results are as follows: Figure 1 shown.

[0034] (2) Take 6 mg of the three-component blend system and put it into a crucible. In a nitrogen atmosphere, heat it from 30°C to 300°C at 10°C / min and perform DSC test. The test results are as follows: Figure 2 shown.

[0035] Curing process of the above aromatic nitrile resin composite curing system:

[0036] 2 g of the three-component blend system was placed in a 25 ml single-necked bottle, stirred at 160 ° C for 0.5 h under a nitrogen atmosphere for melt prepolymerization, and then cast into a copper mold with a size of 60 mm × 40 mm × 4 mm. Then, under a nitrogen atmosphere, the mixture was cured at 200 ° C for 2 h, 250 ° C for 4 h, and 300 ° C for 4 h at a heating rate of 5 ° C / min. After curing, it was naturally cooled to room temperature to obtain an aromatic nitrile resin.

[0037] Dynamic mechanical analysis (DMA) was used to test the thermomechanical properties of the aromatic nitrile resin obtained by curing, and the DMA curves of storage modulus and loss tangent as a function of temperature were obtained, such as Figure 3 shown.

[0038] Comparative Example 1

[0039] 0.67 mmol of elemental sulfur (S8) and 6 mmol of 2BDDPN were ground and blended with the aid of 8 ml of acetone as a solvent, and then rotary dried at 40°C for 12 h to obtain a two-component blend system (2BDDPN-S8).

[0040] Investigation of curing kinetics of blending system:

[0041] (1) Take 6 mg of the two-component blend system and put it into a crucible. In a nitrogen atmosphere, heat it from 30°C to 800°C at 10°C / min for TGA test. The test results are as follows: Figure 1 shown.

[0042] (2) Take 6 mg of the two-component blend system and put it into a crucible. In a nitrogen atmosphere, heat it from 30°C to 300°C at 10°C / min and perform DSC test. The test results are as follows: Figure 2 shown.

[0043] Comparative Example 2

[0044] 1.33 mmol of p-phenylenediamine and 6 mmol of 2BDDPN were ground and blended with the aid of 8 ml of acetone as a solvent, and then dried by rotary evaporation at 40° C. for 12 h to obtain a two-component blend system (2BDDPN-DMAM).

[0045] Investigation of curing kinetics of blending system:

[0046] (1) Take 6 mg of the two-component blend system and put it into a crucible. In a nitrogen atmosphere, heat it from 30°C to 800°C at 10°C / min for TGA test. The test results are as follows: Figure 1 shown.

[0047] (2) Take 6 mg of the two-component blend system and put it into a crucible. In a nitrogen atmosphere, heat it from 30°C to 300°C at 10°C / min and perform DSC test. The test results are as follows: Figure 2 shown.

[0048] Figure 1 and Figure 2 The results show that the sulfur-containing aromatic nitrile resin composite curing system described in Example 1 has a residual carbon rate of 66.5% at 800°C, indicating that a curing reaction has occurred, and its curing exothermic peak temperature has dropped to 188°C, indicating that it has high curing activity. Figure 3 The DMA spectrum shows that the glass transition temperature (Tg) of the cured resin is greater than 390°C, exhibiting excellent thermomechanical properties.

[0049] Example 2

[0050] The aromatic nitrile-based resin composite curing system provided in this embodiment includes 1.1 mmol of elemental sulfur (S8) and 4 mmol of tertiary amine-containing phthalonitrile DMEPN (as shown in structural formula II).

[0051] Structural Formula II: ;

[0052] The preparation steps of monomer DMEON are as follows:

[0053] 3-[1-(Dimethylamino)ethyl]phenol (15.13 mmol), 4-nitrophthalonitrile (15.13 mmol), potassium carbonate (22.70 mmol), and 50 ml of dimethylacetamide were added to a 100 ml single-necked flask. N2 was then bubbled through the flask, and the temperature was raised to 40°C with stirring for 24 hours. After cooling to room temperature, the reaction solution was poured into 500 ml of deionized water and extracted with 500 ml of ethyl acetate. The supernatant ethyl acetate was dried on a rotary evaporator at 70°C for 8 hours to obtain the product as a yellowish-yellow liquid (yield 80.6%).

[0054] The DMEPN H NMR spectrum signals are as follows:

[0055] 1 H NMR (400 MHz, DMSO-d6) δ 8.09 (dd, J = 8.8, 1.2 Hz, 1H), 7.76 (d, J= 2.3 Hz, 1H), 7.53-6.87 (m, 5H), 2.30-1.93 (m, 6H), 1.26 (d, J = 6.6 Hz,3H).

[0056] Sulfur and DMEPN were ground and blended with the aid of 8 ml of acetone as a solvent, and then rotary dried at 40°C for 12 h to obtain a two-component blend system (DMEPN-S8).

[0057] Investigation of curing kinetics of blending system:

[0058] (1) Take 6 mg of the two-component blend system and put it into a crucible. In a nitrogen atmosphere, heat it from 30°C to 800°C at 10°C / min for TGA test. The test results are as follows: Figure 4 shown.

[0059] (2) Take 6 mg of the two-component blend system and put it into a crucible. In a nitrogen atmosphere, heat it from -50°C to 300°C at 10°C / min and perform DSC test. The test results are as follows: Figure 5 shown.

[0060] Curing process of the above aromatic nitrile resin composite curing system:

[0061] 2 g of the two-component blend system was placed in a 25 ml single-necked bottle, stirred at 140 ° C for 0.5 h under a nitrogen atmosphere for melt prepolymerization, and then cast into a copper mold with a size of 60 mm × 40 mm × 4 mm. Then, under a nitrogen atmosphere, the mixture was cured at 200 ° C for 3 h, 220 ° C for 3 h, and 240 ° C for 3 h at a heating rate of 5 ° C / min. After curing, it was naturally cooled to room temperature to obtain an aromatic nitrile resin.

[0062] Dynamic mechanical analysis (DMA) was used to test the thermomechanical properties of the aromatic nitrile resin obtained by curing, and the DMA curves of storage modulus and loss tangent as a function of temperature were obtained, such as Figure 6 shown.

[0063] Comparative Example 3

[0064] 6 mg of DMEPN was placed in a crucible and heated from 30°C to 800°C at 10°C / min under nitrogen atmosphere for TGA test. The test results are as follows: Figure 4 shown.

[0065] 6 mg of DMEPN was placed in a crucible and heated from -50°C to 300°C at 10°C / min under nitrogen atmosphere for DSC test. The test results are shown in the figure. Figure 5 shown.

[0066] Figure 4 and Figure 5 It shows that pure DMEPN shows a single-step weight loss with a residual carbon rate of 0; however, after adding sulfur, it has a significant weight loss transition with a residual carbon rate of 51%. The initial curing temperature of the blended system is reduced to 170°C, and the composite curing system containing tertiary amine activated groups shows excellent curing activity. At the same time, Figure 6 The DMA curve shows that the cured resin has a Tg greater than 350°C, exhibiting excellent thermomechanical properties.

[0067] Example 3

[0068] The aromatic nitrile-based resin composite curing system provided in this embodiment includes 3.5 mmol of elemental sulfur (S8) and 8.3 mmol of phenolic hydroxyl-containing phthalonitrile 3HPN (as shown in structural formula III).

[0069] Structural Formula III: ;

[0070] The monomer 3HPN was prepared by a method disclosed in the art, see Wang Jianbo, Hu Jianghuai, Zeng Ke, Yang Gang, Preparation of self-promoted hydroxy-containing phthalonitrile resins by an in situ reaction, Rsc Advances, 2015, 5(127):105038-105046.

[0071] Sulfur and 3HPN were ground and blended with the aid of 8 ml of acetone as a solvent, and then rotary dried at 40°C for 12 h to obtain a two-component blend system (3HPN-S8).

[0072] Investigation of curing kinetics of blending system:

[0073] (1) Take 6 mg of the two-component blend system and put it into a crucible. In a nitrogen atmosphere, heat it from 30°C to 800°C at 10°C / min for TGA test. The test results are as follows: Figure 7 shown.

[0074] (2) Take 6 mg of the two-component blend system and put it into a crucible. In a nitrogen atmosphere, heat it from 30°C to 300°C at 10°C / min and perform DSC test. The test results are as follows: Figure 8 shown.

[0075] Curing process of the above aromatic nitrile resin composite curing system:

[0076] 2 g of the two-component blend system was placed in a 25 ml single-necked bottle, stirred at 140 ° C for 0.5 h under a nitrogen atmosphere for melt prepolymerization, and then cast into a copper mold with a size of 60 mm × 40 mm × 4 mm. Then, under a nitrogen atmosphere, the mixture was heated at a rate of 5 ° C / min at 200 ° C for 3 h, 225 ° C for 3 h, 250 ° C for 3 h, and 275 ° C for 3 h. After curing, it was naturally cooled to room temperature to obtain an aromatic nitrile resin.

[0077] Dynamic mechanical analysis (DMA) was used to test the thermomechanical properties of the aromatic nitrile resin obtained by curing, and the DMA curves of storage modulus and loss tangent as a function of temperature were obtained, such as Figure 9shown.

[0078] Comparative Example 4

[0079] 6 mg of 3HPN was placed in a crucible and heated from 30°C to 800°C at 10°C / min under nitrogen atmosphere for TGA test. The test results are as follows: Figure 7 shown.

[0080] 6 mg of 3HPN was placed in a crucible and heated from 30°C to 300°C at 10°C / min under a nitrogen atmosphere for DSC testing. The test results are as follows: Figure 8 shown.

[0081] Figure 7 and Figure 8 It shows that both 3HPN and the blend system have a high residual carbon rate, but compared with the slow exothermic process of 3HPN monomer in the high temperature range (>250℃), the blend system has a curing exothermic peak at 218℃, showing a higher curing activity. Figure 9 The DMA curve shows that the cured resin has a Tg greater than 360°C, exhibiting excellent thermomechanical properties.

[0082] Example 4

[0083] The aromatic nitrile-based resin composite curing system provided in this embodiment includes 2 mmol of elemental sulfur (S8) and 8 mmol of eugenol-derived phthalonitrile EPN (as shown in structural formula IV).

[0084] Structural Formula IV: ;

[0085] The monomer EPN was prepared by a method disclosed in the art, see An-ran Wanga, Abdul Qadeer Dayoa, Li-wu Zub, Yi-le Xua, Dan Lva, Sha Songa, Tao Tangc, Wen-bin Liua, Jun Wanga, Bao-chang Gaod, Bio-based phthalonitrile compounds: Synthesis, curing behavior, thermomechanical and thermal properties; Reactive and Functional Polymers 127 (2018) 1-9.

[0086] Sulfur element and EPN were ground and blended with the aid of 8 ml of acetone as a solvent, and then rotary dried at 40°C for 12 h to obtain a two-component blend system (EPN-S8).

[0087] Investigation of curing kinetics of blending system:

[0088] (1) Take 6 mg of the two-component blend system and put it into a crucible. In a nitrogen atmosphere, heat it from 30°C to 800°C at 10°C / min for TGA test. The test results are as follows: Figure 10 shown.

[0089] (2) Take 6 mg of the two-component blend system and put it into a crucible. In a nitrogen atmosphere, heat it from 30°C to 300°C at 10°C / min and perform DSC test. The test results are as follows: Figure 11 shown.

[0090] Curing process of the above aromatic nitrile resin composite curing system:

[0091] 2 g of the two-component blend system was placed in a 25 ml single-necked bottle, stirred at 170 ° C for 0.5 h under a nitrogen atmosphere for melt prepolymerization, and then cast into a copper mold with a size of 60 mm × 40 mm × 4 mm. Then, under a nitrogen atmosphere, the mixture was cured at 200 ° C for 1 h, 225 ° C for 3 h, and 250 ° C for 3 h at a heating rate of 5 ° C / min. After curing, it was naturally cooled to room temperature to obtain an aromatic nitrile resin.

[0092] Dynamic mechanical analysis (DMA) was used to test the thermomechanical properties of the aromatic nitrile resin obtained by curing, and the DMA curves of storage modulus and loss tangent as a function of temperature were obtained, such as Figure 12 shown.

[0093] Comparative Example 5

[0094] 6 mg of EPN was placed in a crucible and the temperature was raised from 30°C to 800°C at 10°C / min under nitrogen atmosphere for TGA test. The test results are as follows: Figure 10 shown.

[0095] 6 mg of EPN was placed in a crucible and heated from 30°C to 300°C at 10°C / min under nitrogen atmosphere for DSC test. The test results are as follows: Figure 11 shown.

[0096] Comparative Example 6

[0097] Take 6 mg of sulfur (S8) and put it into a crucible. In a nitrogen atmosphere, heat it from 30°C to 800°C at 10°C / min for TGA test. The test results are as follows: Figure 10 shown.

[0098] Figure 10 and Figure 11The results show that pure EPN exhibits a single-step mass loss with a residual carbon rate of 8.5%. However, after adding sulfur, it has a significant weight loss transition with a residual carbon rate of 61.0%, indicating that a curing reaction has occurred. The peak temperature of the curing exotherm drops to 218°C, indicating that the composite curing system containing eugenol-derived activated groups exhibits excellent curing activity. Figure 12 It can be seen from the figure that the Tg of the embodiment is higher than 340°C. At a low curing temperature of 250°C and a short curing period, the thermomechanical properties of the cured phthalonitrile resin are at an excellent level.

[0099] Example 5

[0100] The aromatic nitrile-based resin composite curing system provided in this embodiment includes 0.67 mmol of elemental sulfur (S8), 1.33 mmol of p-phenylenediamine (DMAM, activator), and 6 mmol of imidazole dinitrile monomer PDBDCI (as shown in structural formula V).

[0101] Structural Formula V: ;

[0102] Sulfur, p-phenylenediamine and PDBDCI were ground and blended with the aid of 8 ml of acetone as a solvent, and then rotary evaporated and dried at 40°C for 12 h to obtain a three-component blend system (PDBDCI-S8-DMAM).

[0103] Investigation of curing kinetics of blending system:

[0104] (1) Take 6 mg of the three-component blend system and put it into a crucible. In a nitrogen atmosphere, heat it from 30°C to 800°C at 10°C / min for TGA test. The test results are as follows: Figure 13 shown.

[0105] (2) Take 6 mg of the three-component blend system and put it into a crucible. In a nitrogen atmosphere, heat it from 30°C to 300°C at 10°C / min and perform DSC test. The test results are as follows: Figure 14 shown.

[0106] Curing process of the above aromatic nitrile resin composite curing system:

[0107] 2 g of the three-component blend system was placed in a 25 ml single-necked bottle, stirred at 180 ° C for 0.5 h under a nitrogen atmosphere for melt prepolymerization, and then cast into a copper mold with a size of 60 mm × 40 mm × 4 mm. Then, under a nitrogen atmosphere, the mixture was cured at 225 ° C for 3 h, 250 ° C for 3 h, 275 ° C for 3 h, and 300 ° C for 3 h at a heating rate of 5 ° C / min. After curing, it was naturally cooled to room temperature to obtain an aromatic nitrile resin.

[0108] Dynamic mechanical analysis (DMA) was used to test the thermomechanical properties of the aromatic nitrile resin obtained by curing, and the DMA curves of storage modulus and loss tangent as a function of temperature were obtained, such as Figure 15 shown.

[0109] Comparative Example 7

[0110] 0.67 mmol of elemental sulfur (S8) and 6 mmol of PDBDCI were ground and blended with the aid of 8 ml of acetone as a solvent, and then rotary dried at 40 °C for 12 h to obtain a two-component blend system (PDBDCI-S8).

[0111] Investigation of curing kinetics of blending system:

[0112] (1) Take 6 mg of the two-component blend system and put it into a crucible. In a nitrogen atmosphere, heat it from 30°C to 800°C at 10°C / min for TGA test. The test results are as follows: Figure 13 shown.

[0113] (2) Take 6 mg of the two-component blend system and put it into a crucible. In a nitrogen atmosphere, heat it from 30°C to 300°C at 10°C / min and perform DSC test. The test results are as follows: Figure 14 shown.

[0114] Comparative Example 8

[0115] 1.33 mmol of p-phenylenediamine and 6 mmol of PDBDCI were ground and blended with the aid of 8 ml of acetone as a solvent, and then dried by rotary evaporation at 40°C for 12 h to obtain a two-component blend system (PDBDCI-DMAM).

[0116] Investigation of curing kinetics of blending system:

[0117] (1) Take 6 mg of the two-component blend system and put it into a crucible. In a nitrogen atmosphere, heat it from 30°C to 800°C at 10°C / min for TGA test. The test results are as follows: Figure 13 shown.

[0118] (2) Take 6 mg of the two-component blend system and put it into a crucible. In a nitrogen atmosphere, heat it from 30°C to 300°C at 10°C / min and perform DSC test. The test results are as follows: Figure 14 shown.

[0119] Figure 13 and Figure 14 The results show that the sulfur-containing aromatic nitrile resin composite curing system described in Example 5 has a residual carbon rate of 50.3% at 800°C, indicating that a curing reaction has occurred, and its curing exothermic peak temperature has dropped to 214°C, indicating that it has high curing activity. Figure 15The DMA curve shows that the glass transition temperature (Tg) of the cured resin is greater than 390°C, exhibiting excellent thermomechanical properties.

[0120] Example 6

[0121] The aromatic nitrile-based resin composite curing system provided in this embodiment includes 0.55 mmol of elemental sulfur (S8), 2 mmol of DMEPN (as shown in structural formula II), and 5 mmol of 2BDDPN (as shown in structural formula I).

[0122] Sulfur, DMEPN and 2BDDPN were ground and blended with the aid of 8 ml of acetone as a solvent, and then dried by rotary evaporation at 40° C. for 12 h to obtain a three-component blending system.

[0123] 2 g of the three-component blend system was placed in a 25 ml single-necked bottle, stirred at 160 ° C for 0.5 h under a nitrogen atmosphere for melt prepolymerization, and then cast into a copper mold with a size of 60 mm × 40 mm × 4 mm. Then, the mixture was cured at 200 ° C for 4 h, 250 ° C for 4 h, and 300 ° C for 4 h at a heating rate of 5 ° C / min under a nitrogen atmosphere. After curing, it was naturally cooled to room temperature to obtain an aromatic nitrile resin.

[0124] Dynamic mechanical analysis (DMA) was used to test the thermal mechanical properties and obtain the DMA curves of storage modulus and loss tangent as a function of temperature, such as Figure 16 As shown, DMA shows that the cured resin Tg is greater than 370 °C, exhibiting excellent thermomechanical properties.

[0125] Implementation 7

[0126] The aromatic nitrile resin composite curing system provided in this embodiment includes 0.2 mmol of elemental sulfur (S8), 1.6 mmol of p-phenylenediamine (DMAM, activator), and 5 mmol of aromatic nitrile monomer 2BDDPN (as shown in structural formula I).

[0127] Structural Formula I: , R is ;

[0128] Sulfur, DMAP and 2BDDPN were ground and blended with the aid of 10 ml of acetone as a solvent, and then rotary dried at 40°C for 12 h to obtain a three-component blend system (2BDDPN-S8-DMAM-1).

[0129] 2 g of the three-component blend system was placed in a 25 ml single-necked bottle, stirred at 160 ° C for 0.5 h under a nitrogen atmosphere for melt prepolymerization, and then cast into a copper mold with a size of 60 mm × 40 mm × 4 mm. Then, under a nitrogen atmosphere, the mixture was cured at 200 ° C for 4 h, 250 ° C for 4 h, and 300 ° C for 4 h at a heating rate of 5 ° C / min. After the curing, it was naturally cooled to room temperature to obtain an aromatic nitrile resin. The Tg of the prepared resin was greater than 350 ° C.

[0130] Example 8

[0131] The aromatic nitrile resin composite curing system provided in this embodiment includes 2 mmol of elemental sulfur (S8), 0.5 mmol of octanediamine (ODAM, activator), and 6 mmol of aromatic nitrile monomer 3BOCN (as shown in structural formula VI).

[0132] Structural formula VI: , R is ;

[0133] Sulfur, ODAM and 3BOCN were ground and blended with the aid of 10 ml of acetone as a solvent, and then rotary dried at 40°C for 12 h to obtain a three-component blend system (3BOCN-S8-ODAM).

[0134] 2 g of the three-component blend system was placed in a 25 ml single-necked bottle, stirred at 175 ° C for 0.5 h under a nitrogen atmosphere for melt prepolymerization, and then cast into a copper mold with a size of 60 mm × 40 mm × 4 mm. Then, under a nitrogen atmosphere, the mixture was cured at 200 ° C for 4 h, 225 ° C for 4 h, and 250 ° C for 4 h at a heating rate of 5 ° C / min. After the curing, it was naturally cooled to room temperature to obtain an aromatic nitrile resin. The Tg of the prepared resin was greater than 340 ° C.

[0135] Those skilled in the art will appreciate that the embodiments herein are intended to help readers understand the principles of the present invention, and it should be understood that the scope of protection of the present invention is not limited to such specific descriptions and embodiments. Those skilled in the art may make various other specific variations and combinations based on the technical teachings disclosed herein without departing from the essence of the present invention, and such variations and combinations are still within the scope of protection of the present invention.

Claims

1. An aromatic nitrile resin composite curing system, characterized in that: Scheme 1: obtained by curing sulfur, an activator and one or more aromatic nitrile monomers; the activator is a nucleophilic reagent that can ring-open sulfur, or a reagent that reacts with sulfur to produce sulfur anions, thiols or sulfur free radicals; Alternatively, Option 2: obtained by curing sulfur and one or more aromatic nitrile monomers; the at least one aromatic nitrile monomer contains an activated functional group; the activated functional group has any one of the following structural formulas: 、 、 、 、 、 、 、 。 2. The aromatic nitrile-based resin composite curing system according to claim 1, characterized in that: In the first embodiment, the molar ratio of the sulfur element, the activator, and the aromatic nitrile monomer is (1-50):(1-100):100; In the second scheme, the molar ratio of the sulfur element to the aromatic nitrile monomer is (1-50):

100.

3. The aromatic nitrile-based resin composite curing system according to claim 2, characterized in that: The molar ratio of the sulfur element to the activator is 1:8 to 4:

1.

4. The aromatic nitrile-based resin composite curing system according to claim 2, characterized in that: The activator is a compound containing an amino group, a phenolic hydroxyl group, an olefin or an alkyne group.

5. The aromatic nitrile-based resin composite curing system according to claim 4, characterized in that: The amine group is a primary amine, a secondary amine or a tertiary amine.

6. The aromatic nitrile-based resin composite curing system according to claim 4, characterized in that: The activator is a compound having any of the following structural formulas: 、 、 、 、 、 、 、 、 or .

7. The aromatic nitrile-based resin composite curing system according to claim 1, characterized in that: The aromatic nitrile monomer is an aromatic nitrile monomer containing a phthalonitrile or imidazole dinitrile group.

8. The aromatic nitrile-based resin composite curing system according to claim 7, characterized in that: In the first embodiment, the aromatic nitrile monomer is a compound having any of the following structural formulas: ； R is 、 、 or ; 、 、 、 or .

9. The aromatic nitrile-based resin composite curing system according to claim 7, characterized in that: The aromatic nitrile monomer containing an activated functional group is a compound having any of the following structural formulas: 、 、 、 、 、 、 。 10. The aromatic nitrile-based resin composite curing system according to claim 9, characterized in that: When the aromatic nitrile monomer without an active functional group is included in the second scheme, it is a compound having any of the structural formulas: ； R is 、 、 or ; 、 。 11. A method for preparing the aromatic nitrile-based resin composite curing system according to any one of claims 1 to 10, characterized in that: For scheme 1, the preparation method of the aromatic nitrile-based resin composite curing system includes the following steps: The sulfur element, the activator and one or more aromatic nitrile monomers are uniformly mixed in an organic solvent according to a molar ratio, and then melt prepolymerized at 130-190° C. for 0.5-5 hours; the obtained prepolymerized product is then cured at 200-380° C. to obtain an aromatic nitrile resin cured product; For the second scheme, the preparation method of the aromatic nitrile resin composite curing system includes the following steps: The sulfur element and one or more aromatic nitrile monomers are uniformly mixed in an organic solvent according to a molar ratio, and then melt prepolymerized at 130-190° C. for 0.5-5 hours; the obtained prepolymerized product is then cured at 200-380° C. to obtain an aromatic nitrile resin cured product; The organic solvent is acetone, ethanol or tetrahydrofuran.

12. The method for preparing an aromatic nitrile-based resin composite curing system according to claim 11, characterized in that: In Option 1 or Option 2, the curing temperature is 200-300°C, and the curing time is 5-12 hours.

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