Preparation of halogen-free flame retardant curing agent and its application in epoxy resin

Preparation of halogen-free flame retardant curing agent and its application in epoxy resin | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Preparation of halogen-free flame retardant curing agent and its application in epoxy resin jiang lei, jiapeng long, bing Liang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4260856/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract 9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-N-Aminoethylpiperazine(DOPO-AEP) , a phosphorus and nitrogen intumescent flame retardant curing agent was prepared by using acetonitrile as solvent using 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and N-aminoethylpiperazine (AEP) as raw materials. The structure of the flame retardant curing agent DOPO-AEP was analyzed by FTIR, NMR and ESI-MS, and the synthesis method of the target product was determined. In addition, the content of TG in DOPO-AEP was determined by thermogravimetric analyzer, and its thermal properties were comprehensively explored, and based on the obtained results, the curable epoxy resin was selected to prepare DOPO-AEP/EP flame retardant composites. According to the amount of DOPO-AEP added product, different proportions of DOPO-AEP/EP flame retardant composites were prepared, and the actual impact of flame retardant properties and mechanical properties of epoxy resin in different proportions was explored. When the content of DOPO-AEP is 35%, the limiting oxygen index of DOPO-AEP/EP reaches 29.9, which has a significant increase compared with the limiting oxygen index of pure epoxy resin of 19.8, but compared with the content of DOPO-AEP of 30%, the limiting oxygen index of DOPO-AEP/EP is 28.7, and there is no significant increase change. Comprehensive analysis shows that when the component content of DOPO-AEP is 30%, the flame retardant system has a tensile strength of 29.0MPa, an impact strength of 4.5Kj/m 2 and a flexural strength of 73.9MPa, and its limiting oxygen index is as high as 28.7, and the comprehensive performance of the system is the best. By testing the surface morphology of the flame retardant composites after combustion by SEM, it was found that a dense carbon layer was formed on the surface of the epoxy resin cured carbon residue and foamed obviously, indicating that the flame retardant curing performance of DOPO-AEP was good. flame retardant properties Epoxy resin flame retardant composite materials Limiting oxygen index Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Introduction Epoxy resin (EP), as one of the most representative thermosetting polymers, has motivated a worldwide interest due to its outstanding advantages such as excellent chemical corrosion resistance, remarkable dimensional stability and good adhesion, excellent electric insulating property, and low manufacturing cost; therefore, it has been extensively employed in various fields such as aerospace, laminates,coatings, adhesives, and encapsulations [ 1 – 6 ] . Although epoxy resin is widely used in the civil field due to its excellent processing performance, excellent physical properties, low curing shrinkage, and low cost, its flame retardant and fire retardant performance is poor, with the limiting oxygen index only about 19.8%, and it is easy to produce smoke when burning, and death by smoke suffocation and death by inhalation of toxic gases is one of the important causes of death in fire. [ 7 – 9 ] Therefore, how to improve the flame retardant performance of epoxy resin and reduce the release of harmful gases have become a research hotspot. Based on the existence of halogen elements, flame retardants are usually divided into two types: halogen-containing and halogen-free, among them, the former has excellent flame retardant effect, so it is currently more commonly used, but it should be noted that this kind of halogen-containing flame retardant materials usually form a large amount of smoke in the process of flame retardant, accompanied by various toxic corrosive gases, which will cause great secondary harm to the nearby environment, so it has been gradually banned; Halogen-free flame retardants can effectively promote the formation of stable expanded coke layer, inhibit the continuous thermal oxidation reaction of the substrate, and increase the thermal degradation temperature, mass loss temperature and coke generation of the curing system. Flame retardants can also be divided into two types: reactive flame retardants and additive flame retardants, although the additive flame retardants are relatively cheap, but there are problems with compatibility, interface and dispersion, which greatly affects the mechanical properties of the material itself; Although the reactive flame retardant is slightly expensive, the elements contained in it are not easy to migrate and not easy to seepage, have excellent and permanent flame retardancy, have almost no effect on the performance of polymer materials, and have good thermal stability. Therefore, in order to solve the high requirements, low cost and high efficiency of the mechanical properties and flame retardant properties of epoxy resin materials in production, industry and other fields, a halogen-free reactive flame retardant epoxy resin curing agent can be designed and introduced into the epoxy resin, which can not only play the role of cross-linking curing, but also achieve efficient flame retardant effect. In this study, DOPO-AEP, a phosphorus and nitrogen intumescent flame retardant curing agent was prepared with acetonitrile as solvent using 9,10-dihydro-9-oxa-10-phosphophenanthrene-10-oxide (DOPO) and N-aminoethylpiperazine (AEP) as raw materials. A series of flame retardant epoxy resin composites DOPO-AEP/EP were prepared by applying them to the flame retardant and curing of bisphenol A epoxy resin, and the flame retardant properties, thermogravimetric properties, tensile strength, impact strength, bending strength and carbon residue morphology of the composites were studied. Experimental Material 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, analytically pure, Jiangsu Poster Chemical Technology Co., Ltd.; N-Aminoethylpiperazine (AEP), analytically pure, Shanghai Maclean's Biochemical Technology Co., Ltd.; Acetonitrile, carbon tetrachloride, analytically pure, Tianjin Fuyu Fine Chemical Co., Ltd.; M-phenylenediamine. Analytical pure, Tianjin Damao Chemical Reagent Factory. Synthesis of DOPO-AEP Add 30ml of acetonitrile, 1.29g (0.01mol) of N-aminoethylpiperazine, and 4.54g (0.021mol) of DOPO to a 100ml three-mouth flask equipped with a condensation reflux device, stir to dissolve, and dissolve under ice bath conditions (< 15°C), 3.38g (0.022mol) of CCl 4 was added dropwise, and the system was heated to 30°C after dropwise addition (about 60min), and the reaction was carried out for 1 hour. After 1 h of reaction, the temperature will be raised to 60°C and the holding reaction will continue for 4 h. The reaction was stopped, reduced to room temperature, filtered and washed with acetonitrile for 3 times, and vacuum dried at 80°C for 12h to obtain a white solid powder that was DOPO-AEP. The equation for the preparation reaction is shown in Fig. 1 . Preparation of DOPO-AEP/EP flame retardant epoxy resin composites At 60°C, MPD and E-44 are mixed to a transparent state, AEP-DOPO is added to mix and evenly vacuum defoam, and when the solution is free of bubbles, it is injected into the pre-heated PTFE mold, solidified at 60°C for 20 minutes, 80°C for 2 hours, and 150°C for 3 hours and 40 minutes, and then naturally lowered to room temperature, and the sample is taken out for polishing to ensure that the sample size is consistent, and the flame retardant epoxy resin composite material is prepared. Preparation of flame retardant epoxy resin composites: MPD is used as curing agent, and the dosage ratio of DOPO-AEP and E-44 is shown in Table 1 . Table 1 E-44 halogen-free flame retardant epoxy system Sample m(E-44)/g m(MPD)/g m(AEP-DOPO)/g EP-0 100 11.9 0 EP-1 100 11.9 20 EP-2 100 11.9 25 EP-3 100 11.9 30 EP-4 100 11.9 35 Measurements The functional group of the compound were analyzed with Fourier infrared spectrometer(NEXUS-470). The KBr tableting method was used to comprehensively characterize the obtained synthetic products. H NMR, P NMR and C NMR were analyzed with a nuclear magnetic resonance spectrometer (Bruker DMX) using D 2 O as the solvent Relative molecular of the compound was analyzed with Mass spectrum (Thermo Scientific) The STA 449C comprehensive thermal analyzer of NETZSCH Instrument Manufacturing Co., Ltd. was used for thermal performance analysis, the temperature range was 50 ~ 800°C, the heating rate was 10°C/min, and the test was carried out under air atmosphere. The tensile strength is tested by an electronic tensile machine. The tensile speed is 10mm/s, and the tensile strength is calculated according to Eq. ( 2.1 ): $${{\sigma }}_{\text{t}}=\frac{\text{P}}{\text{b}\times \text{h}}$$ 2.1 σt——Tensile strength in megapascals (MPa);P——Breaking load in Newtons (N)༛ b——Specimen width in millimeters (mm);h——Specimen thickness in millimeters (mm)。 The bending test was carried out in a three-point bending mode on a CMT6104-type electronic universal testing machine. Each sample was tested five times, and the average results were taken. The GT-7045-MDL digital impact testing machine of High-speed Railway Technology Co., Ltd. was used to test according to the national standard GB/T2567-2008, and the impact velocity of the pendulum impact specimen was 2.9m/s. The formula for calculating impact strength (2.2) is: $${{\sigma }}_{\text{k}}=\frac{\text{A}}{\text{b}\times \text{d}}$$ 2.2 σκ- Impact strength(KJ/m 2 ); A- The work expended to break the specimen༈J༉༛ b- Specimen notch width(mm);d- Specimen notch thickness༈mm༉。 In the course of the study, the test was carried out based on the ASTM D-2863 standard by using the JF-3 oxygen index tester produced by Nanjing Jiangning Analytical Instrument Factory. Sample size 100mm×4mm×2mm. Formula for Limiting Oxygen Index (2.3): The Burning morphology of composite materials were characterized with Scanning electron microscopy ( S-3400N, Hitachi ) Results and Discussion Figure 2 shows the infrared spectra of DOPO, AEP and DOPO-AEP, as shown in Fig. 2 , 914cm − 1 is the P-H bending vibration absorption peak on the raw material DOPO, and 1641cm − 1 is the N-H stretching vibration absorption peak on the raw material AEP. [ 10 ] 2975cm − 1 ,2730cm − 1 is the expansion and contraction vibration absorption peak of C-H on methylene; 1598cm − 1 , 1456cm − 1 is the C = C expansion vibration absorption peak on the aromatic ring, 1444.70cm − 1 is the CH 2 variable angle vibration absorption peak, 995cm − 1 is the P-N bending vibration absorption peak, 1108cm − 1 is the P = O expansion vibration absorption peak, 760cm − 1 is the P-C expansion and contraction vibration absorption peak, 717cm − 1 is the CH 2 out-of-plane bending vibration absorption peak. [ 11 , 12 ] It was proved that the P-H bond disappeared compared with the raw material DOPO, and the N-H bond disappeared compared with N-aminoethylpiperazine, and the P-N bond was formed to produce DOPO-AEP. The preliminary results showed that the preparation of DOPO-AEP was successful. Figure 3 shows the NMR hydrogen spectrum of DOPO-AEP, with a chemical shift (ppm) of about 1.8 attributed to H on -CH 2 on a ring of nitrogen-containing elements, a chemical shift of about 2.6 attributed to H on -CH 2 attached to nitrogen-hydrogen bonds, a chemical shift of about 3 attributed to H on -CH 2 attached to a ring of nitrogen-containing elements, and a chemical shift of about 3.3 attributed to H on N-connected to P. The chemical shift at 7–8 ppm is attributed to the phosphaphenanthrene ring, indicating that the DOPO framework is still preserved. At the same time, the resonance of P-H at 8 ppm from DOPO completely disappeared. Figure 4 shows the NMR phosphorus spectrum of DOPO-AEP, with a chemical shift of about 7.6 attributed to P = O, a chemical shift of about 16.4 attributed to P-C, a chemical shift of about 18.9 attributed to P-O, and a chemical shift of about 20.8 attributed to newly generated P-N. [ 13 , 14 ] Fig. 5 shows the NMR carbon spectrum of DOPO-AEP, with a chemical shift of about 35.4 attributed to C-H, a chemical shift of about 42.7 attributed to C-P, a chemical shift of about 49.1 attributed to C-N, and a chemical shift of about 120.5 attributed to carbon on biphenyls. [ 15 ] Consistent with the structural formula of the target product, the NMR spectra further demonstrated the success of the preparation of DOPO-AEP. ESI-MS represents the various molecular ions and fragment ions with positive charge that are actually formed during the bombardment of high-speed electron flow in the high-vacuum system, and the mass and overall structure of the sample molecules can be obtained by analyzing the ratio m/z between mass m and charge z. Figure 6 shows the DOPO-AEP mass spectrum, which can be observed as m/z = 342, 299, 258, 215, matching the four structures, as shown in Table 2 above. The mass spectrometry results were consistent with the theoretical values, and the combination of infrared spectrogram and nuclear magnetic resonance hydrogen spectra confirmed that the designed structure DOPO-AEP had been successfully prepared. Thermal stability of DOPO-AEP/EP composites The TG curves of DOPO-AEP and epoxy resin composites are shown in Fig. 7 . T 5% represents the weight loss temperature of the corresponding decomposition of 5%. It can be seen that the initial decomposition temperature of the epoxy resin is 300°C, and it goes through two decomposition stages (250–400°C and 400–600°C, respectively). [ 16 , 17 ] At 700°C, 1.9 wt.% carbon residue remains. The T 5% value of EP-1 was lower than that of pure EP, and gradually decreased with the increase of DOPO-AEP content. These phenomena may be due to the early degradation of DOPO due to the breaking of weak bonds such as O = P-O- and P-N. [ 18 ] With the increase of DOPO-AEP content of flame retardant curing agent, the carbon residue value increased from 1.9–5.5%. The final decomposition temperature increased from 610°C to 760°C, indicating that the addition of flame retardant curing agent increased the decomposition temperature of epoxy resin composites and significantly increased the carbon residue rate. This is due to the fact that the polyphosphoric acid produced during the resin decomposition process stimulates EP degradation in the early stages of heating to form enough coke that the phosphorus-rich carbon layer can cover the surface of the burning material and prevent further decomposition within the curing system. [ 19 ] The results show that the flame retardant curing agent DOPO-AEP has a good charring effect, which is of great significance for the flame retardant performance of the matrix material. Mechanical properties of DOPO-AEP/EP composites As shown in Fig. 8 , the increase in the content of DOPO-AEP, a flame retardant curing agent, will change the tensile strength of the epoxy resin composite. EP-4 is a flame retardant curing agent, DOPO-AEP, with a component content of 35%, and its tensile strength is 24.5MPa, which is significantly lower than that of EP-0 pure epoxy resin of 69.3MPa. The results show that the tensile strength of epoxy resin composites decreases gradually with the increase of flame retardant curing agent content. As shown in Fig. 9 , the increased content of DOPO-AEP, a flame retardant curing agent, will change the flexural strength of epoxy resin composites. When the component content of flame retardant curing agent DOPO-AEP is 35%, its flexural strength is 72.5MPa, which is significantly lower than that of pure epoxy resin is 120.9MPa. However, when the component content of DOPO-AEP is 30%, its flexural strength is 73.9MPa, which has no significant decrease. It shows that with the increase of the content of DOPO-AEP component of flame retardant curing agent, the flexural strength of epoxy resin composites decreases, but the downward trend gradually slows down. As shown in Fig. 10 , the impact strength of the epoxy resin composite material is changed as the content of DOPO-AEP component of the flame retardant curing agent increases. When the content of DOPO-AEP component of flame retardant curing agent is 35%, its impact strength is 4.1Kj/m 2 , which is 17.3Kj/m 2 relative to that of pure epoxy resin, which is significantly reduced, but when the content of DOPO-AEP component content of flame retardant curing agent is 30%, its impact strength is 4.5Kj/m 2 , which has no significant decrease. It shows that with the increase of the content of DOPO-AEP component of flame retardant curing agent, the impact strength of epoxy resin composites decreases gradually, and the downward trend gradually slows down. Compared with pure EP, the mechanical properties of DOPO-AEP/EP flame retardant composites decreased slightly, and the tensile strength and impact strength of the flame retardant system showed a trend of rapid decline and slow decline with the gradual increase of DOPO-AEP. When the mass fraction of phosphorus is 2.06%, the tensile strength and impact strength reach 29.0MPa and 4.5Kj/m 2 , respectively, and the mechanical properties are the best. The decline in mechanical properties is due to the fact that the compatibility of DOPO-AEP solid particles in epoxy resin is not good enough, and some of the solid particles act as fillers when curing; [ 20 ] With the curing, the viscosity of the system is increasing, and the intermolecular contact becomes very difficult, so the cross-linking density of epoxy resin decreases, resulting in the decrease of its mechanical properties. Flame retardant properties of DOPO-AEP/EP composites The LOI of the material is measured by the equipment oxygen index meter, and a spline with a width of 10 mm × a thickness of 4 mm is clamped vertically into the combustion cylinder, and then nitrogen and oxygen are injected into the equipment, and the top of the spline is ignited to ensure that the flame can be successfully extinguished for a period of time. Table 5 shows the experimental results of the limiting oxygen index of DOPO-AEP/EP flame retardant composites obtained in this study. Through the observation of Table 5 , it can be found that after curing the pure epoxy resin by using MPD curing agent, the actual LOI can only reach 19.8, which is a flammable material, and after adding DOPO-AEP, the effective improvement of the epoxy resin LOI can be realized, and when 20 copies have been added, the actual flame retardant performance can be increased to 22.8, and the oxygen index of the epoxy resin will continue to improve when the flame retardant DOPO-AEP is continued to be increased. [ 21 ] The reason for this change is that phosphorus and nitrogen can maintain synergy, and then wrap the surface of the polymer system with various non-combustible gases formed during combustion, and enhance the flame retardancy of epoxy resin after expansion and foaming. Table 5 Limiting oxygen index of DOPO-AEP/EP composites Component P% LOI EP-0 0 19.8 EP-1 1.47 22.8 EP-2 1.77 23.8 EP-3 2.06 28.7 EP-4 2.33 29.9 Characterization of carbon layers in DOPO-AEP/EP composites SEM was used to characterize the surface morphology of epoxy composites after combustion, as shown in Fig. 11 . 1) EP-0; 2) EP-1; 3) EP-2; 4) EP-3; 5) EP-4; It can be seen from the figure that the surface of the carbon residue after EP-0 combustion is very smooth, and there is no dense expansive carbon layer. Through the addition of flame retardant curing agent DOPO-AEP, a dense and complete expanded carbon layer is formed on the surface of the burned residual carbon, which effectively prevents the further combustion of epoxy resin and plays a flame retardant effect. When we add 35% flame retardant to EP, the surface morphology of the cured carbon residue will change significantly, followed by the formation of a large number of unevenness and particulate matter. [ 22 ] Combined with the observation results obtained by scanning electron microscopy, the addition of DOPO-AEP flame retardant curing agent can make a huge change in the surface morphology of epoxy resin composite carbon residue. The results show that with the gradual increase of the amount of DOPO-AEP, the denser the carbon layer formed after combustion, and the more the number of expanded bubbles on the surface, which indicates that the synergistic effect of P and N in our synthetic flame retardant curing agent has played a good role, and the N element releases non-combustible gas to dilute the O 2 in the air on the surface of the matrix and the combustible gas decomposed by heating, reduces the oxygen concentration and combustible gas concentration, and the P element forms metaphosphoric acid or polyphosphoric acid dehydrated into charcoal. At the same time, the dense carbon layer formed by expansion foaming can isolate the transmission of oxygen and heat, making the flame retardant effect more significant. Conclusion AEP-DOPO, a phosphorus and nitrogen intumescent flame retardant curing agent, was prepared by using 9,10-dihydro-9-oxa-10-phosphophenanthrene-10-oxide (DOPO) and N-aminoethylpiperazine (AEP). A series of DOPO-AEP/EP flame retardant epoxy resin composites were prepared with AEP-DOPO and MPD as curing agents. The results of TG analysis showed that the addition of flame retardant curing agent increased the decomposition temperature of epoxy resin composites, significantly increased the carbon residue rate, and the flame retardant effect became better and better. The phosphorus content was 2.33%, and the LOI of DOPO-AEP/EP composites reached 29.9, which was significantly higher than that of 22.8 when the phosphorus content was 1.47%. Comprehensive analysis shows that under the same system conditions, after adding 30% flame retardant, the phosphorus content is 2.06%, the tensile strength of the system is 29.0MPa, the impact strength is 4.5Kj/m 2 , and the bending strength is 73.9MPa, and the mechanical properties of the system are the best. SEM was used to characterize the surface morphology of epoxy composites after combustion, which could protect the underlying matrix from heat and combustibles, and showed a good flame retardant effect. Declaration of conflicting interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. Declarations Declaration of conflicting interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4260856","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":294874440,"identity":"d9471f79-7e1e-4ff3-aaa8-b9d8df81cb7b","order_by":0,"name":"jiang lei","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"jiang","middleName":"","lastName":"lei","suffix":""},{"id":294874441,"identity":"277df564-4cf4-46d2-a692-09825c35205a","order_by":1,"name":"jiapeng long","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAx0lEQVRIiWNgGAWjYBACPhDxocJGjp+Z+eADorSwATHjjDNpxpLtbMkGRGth5m05nLjhPI+ZAHFa2HsPv+BtSGPcfJjBjIGhxiaasBaec2kWkjtsmM0OM6Q9YDiWlttAUItEjpmB4Zk0NqCW4waMDYeJ1JLYdpjHuJmxTYJYLcYPDrYdljBgZmYjUgvPGTPGhjNpBhKH2ZgNEojxCz97j/HnPxU29f395z8++FBjQ1gL2G1wZgIRykGA+QORCkfBKBgFo2CkAgCs2jxaa5zTmAAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0002-6225-2401","institution":"Shenyang University of Technology","correspondingAuthor":true,"prefix":"","firstName":"jiapeng","middleName":"","lastName":"long","suffix":""},{"id":294874443,"identity":"592bc6dd-13bb-4b10-b286-9b0bd3d029a3","order_by":2,"name":"bing Liang","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"bing","middleName":"","lastName":"Liang","suffix":""}],"badges":[],"createdAt":"2024-04-13 07:42:14","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4260856/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4260856/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":55492505,"identity":"50357fae-c40c-4e6a-b271-bdc28505c591","added_by":"auto","created_at":"2024-04-29 07:37:42","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":112772,"visible":true,"origin":"","legend":"\u003cp\u003eDOPO-AEP reaction equation\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-4260856/v1/44e8be9cb3834574396d0a71.png"},{"id":55493318,"identity":"a83f7e84-d761-419d-849b-cceafdff6156","added_by":"auto","created_at":"2024-04-29 07:53:42","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":114238,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eInfrared spectra of DOPO, AEP, and \u003c/strong\u003eDOPO-AEP\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-4260856/v1/1f20e6f908098dc887e2c60e.png"},{"id":55491873,"identity":"35cb87be-fd2c-467d-9db7-91e244ce2646","added_by":"auto","created_at":"2024-04-29 07:29:42","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":223371,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eNMR hydrogen spectra of \u003c/strong\u003eDOPO-AEP\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-4260856/v1/abdb360ce33625ba180a9b23.png"},{"id":55491870,"identity":"919141db-2da2-4d0d-bdff-e404df750a13","added_by":"auto","created_at":"2024-04-29 07:29:42","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":127610,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eNMR phosphorus spectra of \u003c/strong\u003eDOPO-AEP\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-4260856/v1/e5269a1ca4ba3fc7bf808540.png"},{"id":55493843,"identity":"027e5fa0-c538-46a4-b45a-5b1b41f88a91","added_by":"auto","created_at":"2024-04-29 08:01:42","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":140488,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eNMR carbon spectra of \u003c/strong\u003eDOPO-AEP\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-4260856/v1/3273eb4e311979c2ba2e73b0.png"},{"id":55493006,"identity":"15210d65-8147-4d2c-b317-bbc960722c01","added_by":"auto","created_at":"2024-04-29 07:45:42","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":51750,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMass spectra of \u003c/strong\u003eDOPO-AEP\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-4260856/v1/0e7b5549fac75b24cdc35152.png"},{"id":55491872,"identity":"2a0a2017-8549-4768-8d4a-b836afd95cab","added_by":"auto","created_at":"2024-04-29 07:29:42","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":84547,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eTG curves of \u003c/strong\u003eDOPO-AEP\u003cstrong\u003e and epoxy resin composites\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage11.png","url":"https://assets-eu.researchsquare.com/files/rs-4260856/v1/dccbef8c064346a15e86723d.png"},{"id":55491880,"identity":"1131f508-b41b-4b17-8faf-621ff2fe5815","added_by":"auto","created_at":"2024-04-29 07:29:42","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":69117,"visible":true,"origin":"","legend":"\u003cp\u003eTensile strength of DOPO-AEP/EPcomposite splines with different ratios was tested\u003c/p\u003e","description":"","filename":"floatimage12.png","url":"https://assets-eu.researchsquare.com/files/rs-4260856/v1/f605ca4305c83f6fbc19a2b9.png"},{"id":55491879,"identity":"24d67cd2-b545-482b-aa3b-840ff382b64c","added_by":"auto","created_at":"2024-04-29 07:29:42","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":70364,"visible":true,"origin":"","legend":"\u003cp\u003eTest the flexural strength of DOPO-AEP/EPcomposite splines with different ratios\u003c/p\u003e","description":"","filename":"floatimage13.png","url":"https://assets-eu.researchsquare.com/files/rs-4260856/v1/baad33b0ff772a9d6b81957b.png"},{"id":55492509,"identity":"6c1dfe49-d6fa-47e0-9b3f-a7022da25125","added_by":"auto","created_at":"2024-04-29 07:37:42","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":65138,"visible":true,"origin":"","legend":"\u003cp\u003eImpact strength test of DOPO-AEP/EPcomposite splines with different ratios\u003c/p\u003e","description":"","filename":"floatimage14.png","url":"https://assets-eu.researchsquare.com/files/rs-4260856/v1/bbd182c2b37399ad63fcd9b2.png"},{"id":55491877,"identity":"cf548cac-cfe8-45fe-aad8-ce65642af9dc","added_by":"auto","created_at":"2024-04-29 07:29:42","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":330170,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSEM image of \u003c/strong\u003eDOPO-AEP/EP\u003cstrong\u003e after combustion\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage15.png","url":"https://assets-eu.researchsquare.com/files/rs-4260856/v1/07123075e740531993e666f2.png"},{"id":56686053,"identity":"812e1670-0cbd-45ef-ac5e-947fda325fc9","added_by":"auto","created_at":"2024-05-17 20:42:05","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2073098,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4260856/v1/c06d5f48-295c-4b85-ae68-4c3d201568e7.pdf"}],"financialInterests":"","formattedTitle":"Preparation of halogen-free flame retardant curing agent and its application in epoxy resin","fulltext":[{"header":"Introduction","content":"\u003cp\u003eEpoxy resin (EP), as one of the most representative thermosetting polymers, has motivated a worldwide interest due to its outstanding advantages such as excellent chemical corrosion resistance, remarkable dimensional stability and good adhesion, excellent electric insulating property, and low manufacturing cost; therefore, it has been extensively employed in various fields such as aerospace, laminates,coatings, adhesives, and encapsulations\u003csup\u003e[\u003cspan additionalcitationids=\"CR2 CR3 CR4 CR5\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eAlthough epoxy resin is widely used in the civil field due to its excellent processing performance, excellent physical properties, low curing shrinkage, and low cost, its flame retardant and fire retardant performance is poor, with the limiting oxygen index only about 19.8%, and it is easy to produce smoke when burning, and death by smoke suffocation and death by inhalation of toxic gases is one of the important causes of death in fire.\u003csup\u003e[\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/sup\u003e Therefore, how to improve the flame retardant performance of epoxy resin and reduce the release of harmful gases have become a research hotspot.\u003c/p\u003e \u003cp\u003eBased on the existence of halogen elements, flame retardants are usually divided into two types: halogen-containing and halogen-free, among them, the former has excellent flame retardant effect, so it is currently more commonly used, but it should be noted that this kind of halogen-containing flame retardant materials usually form a large amount of smoke in the process of flame retardant, accompanied by various toxic corrosive gases, which will cause great secondary harm to the nearby environment, so it has been gradually banned; Halogen-free flame retardants can effectively promote the formation of stable expanded coke layer, inhibit the continuous thermal oxidation reaction of the substrate, and increase the thermal degradation temperature, mass loss temperature and coke generation of the curing system. Flame retardants can also be divided into two types: reactive flame retardants and additive flame retardants, although the additive flame retardants are relatively cheap, but there are problems with compatibility, interface and dispersion, which greatly affects the mechanical properties of the material itself; Although the reactive flame retardant is slightly expensive, the elements contained in it are not easy to migrate and not easy to seepage, have excellent and permanent flame retardancy, have almost no effect on the performance of polymer materials, and have good thermal stability.\u003c/p\u003e \u003cp\u003eTherefore, in order to solve the high requirements, low cost and high efficiency of the mechanical properties and flame retardant properties of epoxy resin materials in production, industry and other fields, a halogen-free reactive flame retardant epoxy resin curing agent can be designed and introduced into the epoxy resin, which can not only play the role of cross-linking curing, but also achieve efficient flame retardant effect.\u003c/p\u003e \u003cp\u003eIn this study, DOPO-AEP, a phosphorus and nitrogen intumescent flame retardant curing agent was prepared with acetonitrile as solvent using 9,10-dihydro-9-oxa-10-phosphophenanthrene-10-oxide (DOPO) and N-aminoethylpiperazine (AEP) as raw materials. A series of flame retardant epoxy resin composites DOPO-AEP/EP were prepared by applying them to the flame retardant and curing of bisphenol A epoxy resin, and the flame retardant properties, thermogravimetric properties, tensile strength, impact strength, bending strength and carbon residue morphology of the composites were studied.\u003c/p\u003e"},{"header":"Experimental","content":"\u003cdiv id=\"Sec3\"\u003e\n \u003ch2\u003eMaterial\u003c/h2\u003e\n \u003cp\u003e\u003cstrong\u003e9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, analytically pure, Jiangsu Poster Chemical Technology Co., Ltd.; N-Aminoethylpiperazine (AEP), analytically pure, Shanghai Maclean\u0026apos;s Biochemical Technology Co., Ltd.; Acetonitrile, carbon tetrachloride, analytically pure, Tianjin Fuyu Fine Chemical Co., Ltd.; M-phenylenediamine. Analytical pure, Tianjin Damao Chemical Reagent Factory.\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eSynthesis of\u003c/strong\u003e DOPO-AEP\u003c/p\u003e\n \u003cp\u003eAdd 30ml of acetonitrile, 1.29g (0.01mol) of N-aminoethylpiperazine, and 4.54g (0.021mol) of DOPO to a 100ml three-mouth flask equipped with a condensation reflux device, stir to dissolve, and dissolve under ice bath conditions (\u0026lt;\u0026thinsp;15\u0026deg;C), 3.38g (0.022mol) of CCl\u003csub\u003e4\u003c/sub\u003e was added dropwise, and the system was heated to 30\u0026deg;C after dropwise addition (about 60min), and the reaction was carried out for 1 hour. After 1 h of reaction, the temperature will be raised to 60\u0026deg;C and the holding reaction will continue for 4 h. The reaction was stopped, reduced to room temperature, filtered and washed with acetonitrile for 3 times, and vacuum dried at 80\u0026deg;C for 12h to obtain a white solid powder that was DOPO-AEP. The equation for the preparation reaction is shown in Fig. \u003cspan\u003e1\u003c/span\u003e.\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003ePreparation of\u003c/strong\u003e DOPO-AEP/EP \u003cstrong\u003eflame retardant epoxy resin composites\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eAt 60\u0026deg;C, MPD and E-44 are mixed to a transparent state, AEP-DOPO is added to mix and evenly vacuum defoam, and when the solution is free of bubbles, it is injected into the pre-heated PTFE mold, solidified at 60\u0026deg;C for 20 minutes, 80\u0026deg;C for 2 hours, and 150\u0026deg;C for 3 hours and 40 minutes, and then naturally lowered to room temperature, and the sample is taken out for polishing to ensure that the sample size is consistent, and the flame retardant epoxy resin composite material is prepared.\u003c/p\u003e\n \u003cp\u003ePreparation of flame retardant epoxy resin composites: MPD is used as curing agent, and the dosage ratio of DOPO-AEP and E-44 is shown in Table \u003cspan\u003e1\u003c/span\u003e.\u003c/p\u003e\n \u003cdiv\u003e\n \u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 1\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eE-44 halogen-free flame retardant epoxy system\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003ccolgroup cols=\"4\"\u003e\u003c/colgroup\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSample\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003em(E-44)/g\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003em(MPD)/g\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003em(AEP-DOPO)/g\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eEP-0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e11.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eEP-1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e11.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eEP-2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e11.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e25\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eEP-3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e11.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eEP-4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e11.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e35\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec4\"\u003e\n \u003ch2\u003eMeasurements\u003c/h2\u003e\n \u003cp\u003eThe functional group of the compound were analyzed with Fourier infrared spectrometer(NEXUS-470). The KBr tableting method was used to comprehensively characterize the obtained synthetic products.\u003c/p\u003e\n \u003cp\u003eH NMR, P NMR and C NMR were analyzed with a nuclear magnetic resonance spectrometer (Bruker DMX) using D\u003csub\u003e2\u003c/sub\u003eO as the solvent\u003c/p\u003e\n \u003cp\u003eRelative molecular of the compound was analyzed with Mass spectrum (Thermo Scientific)\u003c/p\u003e\n \u003cp\u003eThe STA 449C comprehensive thermal analyzer of NETZSCH Instrument Manufacturing Co., Ltd. was used for thermal performance analysis, the temperature range was 50\u0026thinsp;~\u0026thinsp;800\u0026deg;C, the heating rate was 10\u0026deg;C/min, and the test was carried out under air atmosphere.\u003c/p\u003e\n \u003cp\u003eThe tensile strength is tested by an electronic tensile machine. The tensile speed is 10mm/s, and the tensile strength is calculated according to Eq.\u0026nbsp;(\u003cspan\u003e2.1\u003c/span\u003e):\u003c/p\u003e\n \u003cdiv id=\"Equ1\"\u003e\n \u003cdiv id=\"FileID_Equ1\" name=\"EquationSource\"\u003e$${{\\sigma }}_{\\text{t}}=\\frac{\\text{P}}{\\text{b}\\times \\text{h}}$$\u003c/div\u003e\n \u003cdiv\u003e2.1\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003e\u0026sigma;t\u0026mdash;\u0026mdash;Tensile strength in megapascals (MPa);P\u0026mdash;\u0026mdash;Breaking load in Newtons (N)༛\u003c/p\u003e\n \u003cp\u003eb\u0026mdash;\u0026mdash;Specimen width in millimeters (mm);h\u0026mdash;\u0026mdash;Specimen thickness in millimeters (mm)。\u003c/p\u003e\n \u003cp\u003eThe bending test was carried out in a three-point bending mode on a CMT6104-type electronic universal testing machine. Each sample was tested five times, and the average results were taken.\u003c/p\u003e\n \u003cp\u003eThe GT-7045-MDL digital impact testing machine of High-speed Railway Technology Co., Ltd. was used to test according to the national standard GB/T2567-2008, and the impact velocity of the pendulum impact specimen was 2.9m/s. The formula for calculating impact strength (2.2) is:\u003c/p\u003e\n \u003cdiv id=\"Equ2\"\u003e\n \u003cdiv id=\"FileID_Equ2\" name=\"EquationSource\"\u003e$${{\\sigma }}_{\\text{k}}=\\frac{\\text{A}}{\\text{b}\\times \\text{d}}$$\u003c/div\u003e\n \u003cdiv\u003e2.2\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003e\u0026sigma;\u0026kappa;- Impact strength(KJ/m\u003csup\u003e2\u003c/sup\u003e); A- The work expended to break the specimen༈J༉༛\u003c/p\u003e\n \u003cp\u003eb- Specimen notch width(mm);d- Specimen notch thickness༈mm༉。\u003c/p\u003e\n \u003cp\u003eIn the course of the study, the test was carried out based on the ASTM D-2863 standard by using the JF-3 oxygen index tester produced by Nanjing Jiangning Analytical Instrument Factory. Sample size 100mm\u0026times;4mm\u0026times;2mm. Formula for Limiting Oxygen Index (2.3):\u003c/p\u003e\n \u003cdiv id=\"Equ3\"\u003e\n \u003cdiv id=\"FileID_Equ3\" name=\"EquationSource\"\u003e\u003cimg src=\"data:image/png;base64,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\"\u003e\u003c/div\u003e\n \u003c/div\u003e\n \u003cp\u003eThe Burning morphology of composite materials were characterized with Scanning electron microscopy ( S-3400N, Hitachi )\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Results and Discussion","content":"\u003cp\u003eFigure \u003cspan\u003e2\u003c/span\u003e shows the infrared spectra of DOPO, AEP and DOPO-AEP, as shown in Fig. \u003cspan\u003e2\u003c/span\u003e, 914cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is the P-H bending vibration absorption peak on the raw material DOPO, and 1641cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is the N-H stretching vibration absorption peak on the raw material AEP.\u003csup\u003e[\u003cspan\u003e10\u003c/span\u003e]\u003c/sup\u003e 2975cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e,2730cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is the expansion and contraction vibration absorption peak of C-H on methylene; 1598cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, 1456cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is the C\u0026thinsp;=\u0026thinsp;C expansion vibration absorption peak on the aromatic ring, 1444.70cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is the CH\u003csub\u003e2\u003c/sub\u003e variable angle vibration absorption peak, 995cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is the P-N bending vibration absorption peak, 1108cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is the P\u0026thinsp;=\u0026thinsp;O expansion vibration absorption peak, 760cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is the P-C expansion and contraction vibration absorption peak, 717cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is the CH\u003csub\u003e2\u003c/sub\u003e out-of-plane bending vibration absorption peak.\u003csup\u003e[\u003cspan\u003e11\u003c/span\u003e, \u003cspan\u003e12\u003c/span\u003e]\u003c/sup\u003e It was proved that the P-H bond disappeared compared with the raw material DOPO, and the N-H bond disappeared compared with N-aminoethylpiperazine, and the P-N bond was formed to produce DOPO-AEP. The preliminary results showed that the preparation of DOPO-AEP was successful.\u003c/p\u003e\n\u003cp\u003eFigure \u003cspan\u003e3\u003c/span\u003e shows the NMR hydrogen spectrum of DOPO-AEP, with a chemical shift (ppm) of about 1.8 attributed to H on -CH\u003csub\u003e2\u003c/sub\u003e on a ring of nitrogen-containing elements, a chemical shift of about 2.6 attributed to H on -CH\u003csub\u003e2\u003c/sub\u003e attached to nitrogen-hydrogen bonds, a chemical shift of about 3 attributed to H on -CH\u003csub\u003e2\u003c/sub\u003e attached to a ring of nitrogen-containing elements, and a chemical shift of about 3.3 attributed to H on N-connected to P. The chemical shift at 7\u0026ndash;8 ppm is attributed to the phosphaphenanthrene ring, indicating that the DOPO framework is still preserved. At the same time, the resonance of P-H at 8 ppm from DOPO completely disappeared. Figure \u003cspan\u003e4\u003c/span\u003e shows the NMR phosphorus spectrum of DOPO-AEP, with a chemical shift of about 7.6 attributed to P\u0026thinsp;=\u0026thinsp;O, a chemical shift of about 16.4 attributed to P-C, a chemical shift of about 18.9 attributed to P-O, and a chemical shift of about 20.8 attributed to newly generated P-N.\u003csup\u003e[\u003cspan\u003e13\u003c/span\u003e, \u003cspan\u003e14\u003c/span\u003e]\u003c/sup\u003e Fig. \u003cspan\u003e5\u003c/span\u003e shows the NMR carbon spectrum of DOPO-AEP, with a chemical shift of about 35.4 attributed to C-H, a chemical shift of about 42.7 attributed to C-P, a chemical shift of about 49.1 attributed to C-N, and a chemical shift of about 120.5 attributed to carbon on biphenyls.\u003csup\u003e[\u003cspan\u003e15\u003c/span\u003e]\u003c/sup\u003e Consistent with the structural formula of the target product, the NMR spectra further demonstrated the success of the preparation of DOPO-AEP.\u003c/p\u003e\n\u003cp\u003e\u003cimg 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\"\u003e\u003c/p\u003e\n\u003cp\u003eESI-MS represents the various molecular ions and fragment ions with positive charge that are actually formed during the bombardment of high-speed electron flow in the high-vacuum system, and the mass and overall structure of the sample molecules can be obtained by analyzing the ratio m/z between mass m and charge z. Figure \u003cspan\u003e6\u003c/span\u003e shows the DOPO-AEP mass spectrum, which can be observed as m/z\u0026thinsp;=\u0026thinsp;342, 299, 258, 215, matching the four structures, as shown in Table \u003cspan\u003e2\u003c/span\u003e above. The mass spectrometry results were consistent with the theoretical values, and the combination of infrared spectrogram and nuclear magnetic resonance hydrogen spectra confirmed that the designed structure DOPO-AEP had been successfully prepared.\u003c/p\u003e\n\u003cdiv id=\"Sec6\"\u003e\n \u003ch2\u003eThermal stability of DOPO-AEP/EP composites\u003c/h2\u003e\n \u003cp\u003eThe TG curves of DOPO-AEP and epoxy resin composites are shown in Fig. \u003cspan\u003e7\u003c/span\u003e. T\u003csub\u003e5%\u003c/sub\u003e represents the weight loss temperature of the corresponding decomposition of 5%. It can be seen that the initial decomposition temperature of the epoxy resin is 300\u0026deg;C, and it goes through two decomposition stages (250\u0026ndash;400\u0026deg;C and 400\u0026ndash;600\u0026deg;C, respectively).\u003csup\u003e[\u003cspan\u003e16\u003c/span\u003e, \u003cspan\u003e17\u003c/span\u003e]\u003c/sup\u003e At 700\u0026deg;C, 1.9 wt.% carbon residue remains. The T\u003csub\u003e5%\u003c/sub\u003e value of EP-1 was lower than that of pure EP, and gradually decreased with the increase of DOPO-AEP content. These phenomena may be due to the early degradation of DOPO due to the breaking of weak bonds such as O\u0026thinsp;=\u0026thinsp;P-O- and P-N.\u003csup\u003e[\u003cspan\u003e18\u003c/span\u003e]\u003c/sup\u003e With the increase of DOPO-AEP content of flame retardant curing agent, the carbon residue value increased from 1.9\u0026ndash;5.5%. The final decomposition temperature increased from 610\u0026deg;C to 760\u0026deg;C, indicating that the addition of flame retardant curing agent increased the decomposition temperature of epoxy resin composites and significantly increased the carbon residue rate. This is due to the fact that the polyphosphoric acid produced during the resin decomposition process stimulates EP degradation in the early stages of heating to form enough coke that the phosphorus-rich carbon layer can cover the surface of the burning material and prevent further decomposition within the curing system. \u003csup\u003e[\u003cspan\u003e19\u003c/span\u003e]\u003c/sup\u003eThe results show that the flame retardant curing agent DOPO-AEP has a good charring effect, which is of great significance for the flame retardant performance of the matrix material.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec7\"\u003e\n \u003ch2\u003eMechanical properties of DOPO-AEP/EP composites\u003c/h2\u003e\n \u003cp\u003eAs shown in Fig. \u003cspan\u003e8\u003c/span\u003e, the increase in the content of DOPO-AEP, a flame retardant curing agent, will change the tensile strength of the epoxy resin composite. EP-4 is a flame retardant curing agent, DOPO-AEP, with a component content of 35%, and its tensile strength is 24.5MPa, which is significantly lower than that of EP-0 pure epoxy resin of 69.3MPa. The results show that the tensile strength of epoxy resin composites decreases gradually with the increase of flame retardant curing agent content.\u003c/p\u003e\n \u003cp\u003eAs shown in Fig. \u003cspan\u003e9\u003c/span\u003e, the increased content of DOPO-AEP, a flame retardant curing agent, will change the flexural strength of epoxy resin composites. When the component content of flame retardant curing agent DOPO-AEP is 35%, its flexural strength is 72.5MPa, which is significantly lower than that of pure epoxy resin is 120.9MPa. However, when the component content of DOPO-AEP is 30%, its flexural strength is 73.9MPa, which has no significant decrease. It shows that with the increase of the content of DOPO-AEP component of flame retardant curing agent, the flexural strength of epoxy resin composites decreases, but the downward trend gradually slows down.\u003c/p\u003e\n \u003cp\u003eAs shown in Fig. \u003cspan\u003e10\u003c/span\u003e, the impact strength of the epoxy resin composite material is changed as the content of DOPO-AEP component of the flame retardant curing agent increases. When the content of DOPO-AEP component of flame retardant curing agent is 35%, its impact strength is 4.1Kj/m\u003csup\u003e2\u003c/sup\u003e, which is 17.3Kj/m\u003csup\u003e2\u003c/sup\u003e relative to that of pure epoxy resin, which is significantly reduced, but when the content of DOPO-AEP component content of flame retardant curing agent is 30%, its impact strength is 4.5Kj/m\u003csup\u003e2\u003c/sup\u003e, which has no significant decrease. It shows that with the increase of the content of DOPO-AEP component of flame retardant curing agent, the impact strength of epoxy resin composites decreases gradually, and the downward trend gradually slows down.\u003c/p\u003e\n \u003cp\u003eCompared with pure EP, the mechanical properties of DOPO-AEP/EP flame retardant composites decreased slightly, and the tensile strength and impact strength of the flame retardant system showed a trend of rapid decline and slow decline with the gradual increase of DOPO-AEP. When the mass fraction of phosphorus is 2.06%, the tensile strength and impact strength reach 29.0MPa and 4.5Kj/m\u003csup\u003e2\u003c/sup\u003e, respectively, and the mechanical properties are the best. The decline in mechanical properties is due to the fact that the compatibility of DOPO-AEP solid particles in epoxy resin is not good enough, and some of the solid particles act as fillers when curing;\u003csup\u003e[\u003cspan\u003e20\u003c/span\u003e]\u003c/sup\u003e With the curing, the viscosity of the system is increasing, and the intermolecular contact becomes very difficult, so the cross-linking density of epoxy resin decreases, resulting in the decrease of its mechanical properties.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec8\"\u003e\n \u003ch2\u003eFlame retardant properties of DOPO-AEP/EP composites\u003c/h2\u003e\n \u003cp\u003eThe LOI of the material is measured by the equipment oxygen index meter, and a spline with a width of 10 mm \u0026times; a thickness of 4 mm is clamped vertically into the combustion cylinder, and then nitrogen and oxygen are injected into the equipment, and the top of the spline is ignited to ensure that the flame can be successfully extinguished for a period of time. Table \u003cspan\u003e5\u003c/span\u003e shows the experimental results of the limiting oxygen index of DOPO-AEP/EP flame retardant composites obtained in this study.\u003c/p\u003e\n \u003cp\u003eThrough the observation of Table \u003cspan\u003e5\u003c/span\u003e, it can be found that after curing the pure epoxy resin by using MPD curing agent, the actual LOI can only reach 19.8, which is a flammable material, and after adding DOPO-AEP, the effective improvement of the epoxy resin LOI can be realized, and when 20 copies have been added, the actual flame retardant performance can be increased to 22.8, and the oxygen index of the epoxy resin will continue to improve when the flame retardant DOPO-AEP is continued to be increased.\u003csup\u003e[\u003cspan\u003e21\u003c/span\u003e]\u003c/sup\u003e The reason for this change is that phosphorus and nitrogen can maintain synergy, and then wrap the surface of the polymer system with various non-combustible gases formed during combustion, and enhance the flame retardancy of epoxy resin after expansion and foaming. \u0026nbsp;\u003c/p\u003e\n \u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 5\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003e\u003cstrong\u003eLimiting oxygen index of\u003c/strong\u003e DOPO-AEP/EP \u003cstrong\u003ecomposites\u003c/strong\u003e\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eComponent\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eP%\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eLOI\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eEP-0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e19.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eEP-1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.47\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e22.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eEP-2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1.77\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e23.8\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eEP-3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e28.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eEP-4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e29.9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003cp\u003e\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec9\"\u003e\n \u003ch2\u003eCharacterization of carbon layers in DOPO-AEP/EP composites\u003c/h2\u003e\n \u003cp\u003eSEM was used to characterize the surface morphology of epoxy composites after combustion, as shown in Fig. \u003cspan\u003e11\u003c/span\u003e. 1) EP-0; 2) EP-1; 3) EP-2; 4) EP-3; 5) EP-4; It can be seen from the figure that the surface of the carbon residue after EP-0 combustion is very smooth, and there is no dense expansive carbon layer. Through the addition of flame retardant curing agent DOPO-AEP, a dense and complete expanded carbon layer is formed on the surface of the burned residual carbon, which effectively prevents the further combustion of epoxy resin and plays a flame retardant effect. When we add 35% flame retardant to EP, the surface morphology of the cured carbon residue will change significantly, followed by the formation of a large number of unevenness and particulate matter.\u003csup\u003e[\u003cspan\u003e22\u003c/span\u003e]\u003c/sup\u003e Combined with the observation results obtained by scanning electron microscopy, the addition of DOPO-AEP flame retardant curing agent can make a huge change in the surface morphology of epoxy resin composite carbon residue. The results show that with the gradual increase of the amount of DOPO-AEP, the denser the carbon layer formed after combustion, and the more the number of expanded bubbles on the surface, which indicates that the synergistic effect of P and N in our synthetic flame retardant curing agent has played a good role, and the N element releases non-combustible gas to dilute the O\u003csub\u003e2\u003c/sub\u003e in the air on the surface of the matrix and the combustible gas decomposed by heating, reduces the oxygen concentration and combustible gas concentration, and the P element forms metaphosphoric acid or polyphosphoric acid dehydrated into charcoal. At the same time, the dense carbon layer formed by expansion foaming can isolate the transmission of oxygen and heat, making the flame retardant effect more significant.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eAEP-DOPO, a phosphorus and nitrogen intumescent flame retardant curing agent, was prepared by using 9,10-dihydro-9-oxa-10-phosphophenanthrene-10-oxide (DOPO) and N-aminoethylpiperazine (AEP). A series of DOPO-AEP/EP flame retardant epoxy resin composites were prepared with AEP-DOPO and MPD as curing agents. The results of TG analysis showed that the addition of flame retardant curing agent increased the decomposition temperature of epoxy resin composites, significantly increased the carbon residue rate, and the flame retardant effect became better and better. The phosphorus content was 2.33%, and the LOI of DOPO-AEP/EP composites reached 29.9, which was significantly higher than that of 22.8 when the phosphorus content was 1.47%. Comprehensive analysis shows that under the same system conditions, after adding 30% flame retardant, the phosphorus content is 2.06%, the tensile strength of the system is 29.0MPa, the impact strength is 4.5Kj/m\u003csup\u003e2\u003c/sup\u003e, and the bending strength is 73.9MPa, and the mechanical properties of the system are the best. SEM was used to characterize the surface morphology of epoxy composites after combustion, which could protect the underlying matrix from heat and combustibles, and showed a good flame retardant effect.\u003c/p\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eDeclaration of conflicting interests\u003c/h2\u003e \u003cp\u003e \u003cb\u003eThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.\u003c/b\u003e \u003c/p\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eDeclaration of conflicting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.\u003c/strong\u003e\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eLuo Q，Yuan Y，Dong C，Huang H，LiuS，Zhao（2016）Highly effective flame retardancy of a novel DPPA-based curing agent for DGEBA epoxy resin. 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Ind Eng Chem Res 50:1881\u0026minus;1892.\u003c/li\u003e\n\u003cli\u003eYang S，Huo S，Wang J，Zhang B，Wang J，Ran S，Fang Z，Song P，Wang H（2021）A highly fire-safe and smoke-suppressive single-component epoxy resin with switchable curing temperature and rapid curing rate. Composites Part B207:108601.\u003c/li\u003e\n\u003cli\u003eWang P，Yang F，Li L，Cai Z（2016）Flame retardancy and mechanical properties of epoxy thermosets modified with a novel DOPO-based oligomer. Polymer Degradation And Stability 129:156\u0026minus;167. \u003c/li\u003e\n\u003cli\u003eTang S，Qian L，Liu X，Dong Y（2016）Gas-phase flame-retardant effects of a bi-group compound based on phosphaphenanthrene and triazine-trione groups in epoxy resin. Polymer Degradation And Stability 133:350\u0026minus;357.\u003c/li\u003e\n\u003cli\u003eSturm H，Schartel B，Wei\u0026szlig; A，Braun U（2012） SEM/EDX: Advanced investigation of structured fire residues and residue formation. Polym Test 31:606\u0026minus;619.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"flame retardant properties, Epoxy resin, flame retardant composite materials, Limiting oxygen index","lastPublishedDoi":"10.21203/rs.3.rs-4260856/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4260856/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e \u003cb\u003e9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-N-Aminoethylpiperazine(DOPO-AEP)\u003c/b\u003e, a phosphorus and nitrogen intumescent flame retardant curing agent was prepared by using acetonitrile as solvent using 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and N-aminoethylpiperazine (AEP) as raw materials. The structure of the flame retardant curing agent DOPO-AEP was analyzed by FTIR, NMR and ESI-MS, and the synthesis method of the target product was determined. In addition, the content of TG in DOPO-AEP was determined by thermogravimetric analyzer, and its thermal properties were comprehensively explored, and based on the obtained results, the curable epoxy resin was selected to prepare DOPO-AEP/EP flame retardant composites. According to the amount of DOPO-AEP added product, different proportions of DOPO-AEP/EP flame retardant composites were prepared, and the actual impact of flame retardant properties and mechanical properties of epoxy resin in different proportions was explored. When the content of DOPO-AEP is 35%, the limiting oxygen index of DOPO-AEP/EP reaches 29.9, which has a significant increase compared with the limiting oxygen index of pure epoxy resin of 19.8, but compared with the content of DOPO-AEP of 30%, the limiting oxygen index of DOPO-AEP/EP is 28.7, and there is no significant increase change. Comprehensive analysis shows that when the component content of DOPO-AEP is 30%, the flame retardant system has a tensile strength of 29.0MPa, an impact strength of 4.5Kj/m\u003csup\u003e2\u003c/sup\u003e and a flexural strength of 73.9MPa, and its limiting oxygen index is as high as 28.7, and the comprehensive performance of the system is the best. By testing the surface morphology of the flame retardant composites after combustion by SEM, it was found that a dense carbon layer was formed on the surface of the epoxy resin cured carbon residue and foamed obviously, indicating that the flame retardant curing performance of DOPO-AEP was good.\u003c/p\u003e","manuscriptTitle":"Preparation of halogen-free flame retardant curing agent and its application in epoxy resin","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-29 07:29:37","doi":"10.21203/rs.3.rs-4260856/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"8074d318-b21e-4fd9-ba7c-5fa157ae1467","owner":[],"postedDate":"April 29th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-05-17T20:33:54+00:00","versionOfRecord":[],"versionCreatedAt":"2024-04-29 07:29:37","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4260856","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4260856","identity":"rs-4260856","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}