Phosphazene Flame Retardant

Phosphazene compounds are a class of compounds with P and N as the basic skeleton, and there is a good synergy between the two elements. Alfa Chemistry provides you with environmentally friendly phosphazene flame retardants, including inorganic phosphazene compounds and organic polyphosphazene flame retardants.

Classification

• Inorganic phosphazene compounds

Mainly include cyclotriphosphazenes, such as hexachlorocyclotriphosphazene, hexaphenoxy cyclotriphosphazene, etc.

• Organic polyphosphazenes

Mainly include linear polyphosphazenes and cyclic cross-linked polyphosphazenes. Currently, polyphosphazene has not been commercialized, and Alfa Chemistry provides custom synthesis services.

Advantages

• It is an environmentally friendly halogen-free flame retardant with less smoke and toxic gases.
• It has high thermal decomposition temperature and flame retardant effect.
• Excellent hydrolysis resistance.
• Excellent heat resistance, can be used for various engineering plastics.
• It can be melted in heat and solvent, so it can be used for various purposes.
• Polyphosphazene has excellent properties of inorganic and organometallic polymers.

Flame Retardant Mechanism

The flame retardant mechanism of phosphazene compound flame retardants (PFRs) is the comprehensive effect of multiple pathways.

• Cooling mechanism

PFRs absorb heat during thermal decomposition.

• Mechanism of isolation film

PFRs can be thermally decomposed to generate phosphoric acid, metaphosphoric acid and polyphosphoric acid, which form a non-volatile protective film on the surface of the polymer material to isolate the air.

• Dilution mechanism

PFRs releases carbon dioxide, ammonia, nitrogen, water vapor and other gases after heating, diluting oxygen, so as to achieve flame retardant synergy.

• Termination chain reaction mechanism

PO· groups are formed during combustion, which can combine with H·, HO· active groups to inhibit the flame.

The general schematic diagram of flame retardant mechanism of polyphosphazenes [1]

Applications

• Polyphosphazene flame retardants with excellent flame retardant effect have been widely used in the field of polymer flame retardant.
• Used for flame retardant of epoxy resin molding compound, copper clad laminate, powder coating, LED light-emitting tube and other polymer materials.
• Used for flame retardant of resin moldings, such as PC, PPE, PET, PBT, HDPE, etc.
• Used for fabric flame retardant, high temperature resistant flame retardant coating, etc.

Research Information

Microencapsulated Phosphazene Flame Retardant

Lijie Qu et al. developed a phosphorus-nitrogen-silicon synergistic flame retardant Si(H) microcapsule system for improving the flame retardancy of epoxy resins (EP). In this work, the microcapsule flame retardant takes silica as the shell, hexaphenoxycyclotriphosphazene as the core, and forms a cross-linked network with EP, thus realizing the ideal of low addition amount and high flame retardancy performance. [2]

Formation of Si(H) microcapsules and cross-linked network of EP composites [2]

References

1. Xia Zhou, et al. (2020). "Polyphosphazenes-based flame retardants: A review," Composites Part B: Engineering 202, 108397.
2. Lijie Qu, et al. (2020). "Improved flame retardancy of epoxy resin composites modified with a low additive content of silica-microencapsulated phosphazene flame retardant," Reactive and Functional Polymers 148, 104485.