Simultaneously Improving the Thermal, Flame‐Retardant and Mechanical Properties of Epoxy Resins Modified by a Novel Multi‐Element Synergistic Flame Retardant

Abstract

are restricted because of the emission of toxic gases and corrosive smoke during combustion. [7][8][9][10] For decades, halogen-free flame retardants, particularly phosphoruscontaining ones have received more attention due to the satisfactory flame-retardant effect in gaseous and condensed phases simultaneously.Phosphorus-containing compounds are the most common halogen-free flame retardants, [11,12] which produce less toxic gases and smoke than halogen-containing compounds. [13,14] They also could impart excellent flame retardancy to EP, as reactive or additive flame retardants. [5] Compared with additive flame retardants, reactive flame retardants impart long-lasting flame retardancy and environmental resistance to EP. [6] Hence, preparation of a novel phosphorus-containing reactive flame retardant has become a hot research spot in recent years. [15] Huo et al. successfully synthesized a novel reactive flame retardant (DPT) through the reaction among DOPO, 1,4-phthalaldehyde, and triacetonediamine. Particularly, EP/DDM/ DPT-4 with 1.0 weight percent (wt%) phosphorus achieves limited oxygen index (LOI) value of 38.3% and UL-94 V-0 rating, while the glass transition temperature decreased by 11 °C. [15] Unfortunately, the traditional phosphorus-containing flame retardant can improve the flame retardant performance of epoxy resin, but its thermal and mechanical properties often decrease. [16,17] Therefore, it is necessary to find an approach to simultaneously improve the thermal, flame-retardant, and mechanical properties.In fact, multi-element synergistic flame retardants, such as P/N/F, [18] P/N/S/Mo, [19] and P/N/Si [20] have been proved to be an effective approach to overcome this predicament. Liu et al. developed a multi-element synergistic flame retardant system through the classical Kabachnik-Fields reaction, which achieved a combination of DOPO, POM, and POSS. The LOI value was 34.5% and the flexural strength increased by 11.7% when the content of POSS-bisDOPO was 20 wt%. [21] Reactive flame retardants containing different elements give EP with excellent flame retardancy and maintain high glass transition temperature. [5] Among the phosphorus-containing reagents, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) with high flame retardancy, good thermal stability, and high reactivity has been widely used in flame retardant modification of EP., [22,23] However, it will cause the bioaccumula tion of phosphorus and deterioration Flame-Retardant Epoxy ResinTo obtain epoxy resins with satisfactory thermal, flame retardant, and mechanical properties, a novel multi-element synergistic flame retardant (PPVSZ) is synthesized through the reaction between PH of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and CC of polysilazane (PVSZ) and utilized as a multi-element synergistic flame retardant for epoxy resins. The flame retardant mechanism is explored by XPS and SEM, confirming that the excellent flame-retardance efficiency owes itself to an optimal flame retardant way which jointly exerts the f...

Synthesis of phosphorus and silicon co‐doped graphitic carbon nitride and its combination with ammonium polyphosphate to enhance the flame retardancy of epoxy resin

“…24 On the other hand, the P N Si ternary system is considered to have a significant synergistic flame retardant effect. 25 However, the construction of a ternary synergistic flame retardant system for g-C 3 N 4 has not been explored. At the same time, considering the advantages of g-C 3 N 4 as a new type of nanomaterial to solve the defect of APP, it is worth researching to apply g-C 3 N 4 of the ternary hybrid system and APP in flame-retardant polymer materials.…”

Novelmulti‐element DOPOderivative towardlow‐flammabilityepoxy resin

“…Meanwhile, the flame-retardant efficiency was improved due to their excellent carbonization and synergistic flame-retardant effect. [27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] According to the above consideration, a novel reactive phosphorus-nitrogen-silicon flame retardants named as DPAK was designed and synthesized to prepare a series of flame-retardant EP. The thermal stability of resultant EP was studied by thermogravimetric analysis (TGA).…”

Highly efficient multielement flame retardant for multifunctional epoxy resin with satisfactory thermal, flame‐retardant, and mechanical properties

“…Among these, 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) is a novel fashioned flame‐retardant intermediate. The P‐H bond is very active on C=O, C=C, and C≡C, which could react with each other to form a variety of DOPO‐based derivatives to improve the flame retardancy of epoxy resins . Unfortunately, the incorporation of a traditional DOPO‐based flame retardant often decreases the thermal and mechanical properties of epoxy resins, and many scholars have tried to overcome this problem with a multielement flame retardant.…”

“…24,25 Liu et al 26 To solve this challenging problem, we have successfully synthesized a novel highly efficient multielement flame retardant (PMSBA) and prepared multifunctional epoxy resins with satisfactory thermal, flame-retardant, and mechanical properties. The chemical structure of PMSBA was characterized by Fourier transform infrared spectroscopy (FTIR), 1 H, and 13 C NMR. The thermal, flame-retardant, and mechanical properties of multifunctional epoxy resins were investigated insightfully.…”