Phosphorus and nitrogen flame retardants use phosphorus and nitrogen as effective active flame retardant components. When they are used in a certain proportion, they have a synergistic flame retardant effect and show superior comprehensive properties in flame retardancy of polymers. Synthesis of a flame retardant polyphenylphosphonic acid diphenyl azo ester (PAPPP). The initial decomposition temperature was 226.85 ℃, and the residual carbon content was 60% at 590 ℃. The LOI of pure PET was 21, LOI up to 33.4% after addition of 10% = PAPPP. The DSC and TG tests showed that PAPPP had low decomposition temperature and high residual carbon content and had good flame retardancy to PET.

Polyphenyl phosphonophenylenediamine (PDPPD). The compound has good thermal stability, the synergistic effect of P-N in the system makes the flame retardant have a significant flame retardant effect on PC, and the LOI of PC can reach 33.2 when 3% is added. However, after the addition of PDPPD in PC, the residual carbon ratio at 800 ℃ is lower than that of pure PC. The addition of the flame retardant can not increase the carbon residue rate of PC, but only increase the LOI value, or some defects exist. Polyphenylphosphonamide has become flame retardant for PC. The pure PC had a LOI of 28.1. When 7% of the flame retardant was added, the LOI was 34.8. The addition of the flame retardant produced a significant flame-retardant effect on PC and improved the flame

retardancy of PC materials.

Poly (4,4-diaminodiphenylmethane spiro pentaerythritol bisphosphonate) (PDSPB) was synthesized. Under N2, the initial decomposition temperature is 254.8 ℃, the residual carbon rate is 42% at 600 ℃, and the maximum weight loss at 300 ℃. The flame retardant can improve the thermal stability of ABS and flame retardant properties, while the carbon residue rate is also greatly increased.

Synthetic polymeric flame retardant (PMPT). The flame retardant has little effect on the mechanical properties of PP and has good compatibility with PP. When 30% flame retardant polypropylene (FR-PP) has a LOI of 28.9, UL-94V0 has passed the UL-94V0 test and the effect is better when using ammonium polyphosphate / pentaerythritol / PMPT compound. Phosphazene flame retardants

Flame retardant POPHA was synthesized for epoxy acrylate (EA) flame retardancy. The system containing the flame retardant has higher thermal stability and flame retardancy than the system without the flame retardant. When the content of POPHA increased from 0 to 20%, the LOI increased from 21 to 29, and the amount of carbon residue at 700 ℃ was increased from 0 to 21.1. The flame retardants showed significant flame retardancy and char formation for EA effect. Poly-4,4-diaminodiphenyl pentaerythritol phosphate (PDBPP) was prepared for flame retardant PP. The initial decomposition temperature was 322 ℃, and the carbon residue rate at 600 ℃ was 15.2%. The LOI of PP increases from 17.4 to 28.0 with the increase of PHRR from 390kW / m2 to 155kW / m2 and the average pyrolysis rate (AHRR) drops from 205kW / m2 to 82kW / m2 with the addition of 30% The relative PP heat release rate peak decreased by 60%, the flame retardant added to improve the thermal stability and flame retardant properties of PP at the same time there is a substantial reduction in heat release rate. Polypirosphates are synthesized. The flame retardant incorporated silane cross-linked polyethylene material, when added 25%, flame retardant silane cross-linked polyethylene LOI was 31.5, passed the UL-94V0 test, the flame retardant has the drawback of low residual carbon content , The initial decomposition temperature needs to be improved. Synthesis of melamine phosphate, calcined in a muffle furnace to obtain melamine polyphosphate.

Phosphazene flame retardants have good thermal stability, the initial decomposition temperature is 320 ℃, higher than the decomposition temperature of most polymer materials, but also has good flame retardant effect. Tao and other synthetic flame retardant PCPP flame retardant polylactic acid (PLA). The initial decomposition temperature of N2 was 263 ℃, the residual carbon content was 62% at 800 ℃ and the LOI of pure PLA was 21. Adding 5% PCPP could make PLA pass UL-94V0 test with LOI reaching 25.2, ; When the content of PCPP was increased to 20%, the LOI reached 28.2, no droplet was dropped and the peak value of heat release was also reduced from 160.60kW / m2 to 47.05kW / m2. The average heat release rate decreased from 271kW / m2 to 122.55kW / m2 , Its addition greatly improves the flame retardant properties of PLA. Tripentaerythritol phosphate melamine salt (MTP) was synthesized. At 600 ℃, the carbon yield of pure PP was only 5.6%. When 20% and 30% MTP were added, the char yields were 9.8% and 14.0%, respectively. When MTP was added to 25%, the LOI of PP reached 32, The UL-94V0 test, the flame retardant can significantly improve the flame retardant properties of PP, but also can effectively promote the PP into charcoal. Synthesis of a non-halogen flame retardant polyphosphazene, the initial decomposition temperature of 280 ~ 290 ℃, the maximum decomposition temperature above 350 ℃, its LOI is 37.5, almost impossible to burn in the air, and passed the UL-94V0 level test. Polyphosphazenes as flame retardant polymer materials in electronic and microelectronic products have broad prospects.