The synthesis of meltable and highly thermostable triazine‐DOPO flame retardant and its application in PA66

Abstract

A melting phosphorous‐nitrogen flame retardant was synthesized via the addition reaction of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) and 2,4,6‐triallyloxy‐1,3,5‐triazine (TAC). The synthesized product from DOPO and TAC (DT) flame retardant possesses high thermal stability with T5wt% at 340°C, which can meet the high‐temperature processing for polyamide 6,6 (PA66) and other engineering plastics. The chemical structures of DT were characterized by nuclear magnetic resonance and infrared spectrometry. The PA composites were fabricated via blending PA66 with DT and poly‐phenyl ether (PPO) as charring agent. The results show that the PA composites exhibit strong flame retardancy with limited oxygen index reaching to 29.0%. As compared to the neat PA66, the total heat release and the effective heat of combustion were decreased by 27% and 21%, respectively. The mechanism study revealed that the thermal cleavage of DT gave the phosphorus‐containing free radicals and incombustible nitrogen‐containing gas, indicating the ability of DT to flame‐inhibition in the gas phase. Moreover, the char formation of the PA66‐based composites was facilitated by the synergistic effect from DT and PPO. This study may gain a potential technical route to manufacture the flame‐retardant PA66 materials for the melt spinning of fibers.

Cosolvent Engineered Phosphaphenanthrene-Based Self-Extinguishing Electrolyte for Safer Lithium-Ion Batteries

“…A sharp endothermic peak is observed at around 123.3 °C in the DSC curve, which is assigned to the melting of DOPO. 25 It is also found that the initial degradation temperature of DOPO is determined to be 211.1 °C.…”

“…9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) (the chemical structure is shown in Figure a), as a typical phosphaphenanthrene-based flame retardant, has the advantages of less smoke (Figure S1), low toxicity, low cost, and highly efficient fire retardancy, which is one of the most widely used retarding agents in the polymer industry. − Initially, Li et al encapsulated DOPO in the cathode material to improve the fire extinguishing performance of the cathode. However, they fail to address the flammability of the electrolyte and the capsule preparation process is usually too complex to industrialize.…”

Thermal Stability and Flame Retardancy of Epoxy Resin with DOPO‐Based Compound Containing Triazole and Hydroxyl Groups

“…[12][13][14][15] There has been reported that the flame-retardant efficiency of DOPO can be further improved through the molecular design method. [16][17][18] Thereinto, introducing the nitrogen-containing group (such as triazine, [19,20] triazinetrione, [21][22][23] Schiff-base, [24][25][26] and hexachlorocyclotriphosphazene [27,28] ) is a feasible way. The phosphophenanthrene group and nitrogen-containing group can exert a P−N synergistic flame-retardant effect to improve the flame retardancy of epoxy thermosets.…”

Thermal Stabilities and Flame Retardancy of Polyamide 66 Prepared by In Situ Loading of Amino-Functionalized Polyphosphazene Microspheres

“…It is particularly important to improve the flame retardancy of PA66 [ 1 ]. Currently, flame retardants are usually added to improve the flame retardancy of PA66, such as halogenated flame retardants decabromodiphenyl ether [ 2 ], metal hydroxide [ 3 ], nano clay [ 4 ], nitrogen compounds [ 5 ], and phosphorus-containing organic compounds [ 6 ]. Because halogenated flame retardants are prone to produce toxic and corrosive smoke and gas during combustion, they easily corrode equipment, harm the environment, and harm the human body.…”