Phosphorus Flame Retardant

Phosphorus and phosphorus compounds have long been used as flame retardants with the advantages of low smoke, non-toxicity, low halogen, and no halogen, etc. Alfa Chemistry is committed to providing you with an extensive catalog of phosphorus flame retardants (PFR).

Classification

• Inorganic phosphorus flame retardant: Mainly includes red phosphorus, ammonium polyphosphate (APP), ammonium phosphate, phosphate and polyphosphate, etc.
• Organophosphorus flame retardants: Mainly includes phosphate ester, phosphaphenanthrene (DOPO), phosphazene compound, organic phosphinic acid and organic phosphinate, etc.
• Click on the categories below for more details and product lists.

Flame Retardant Mechanism

PFRs generally involve two modes of action, including condensed-phase and gas-phase mechanisms. When PFR burns, it generates phosphoric acid, metaphosphoric acid, polymetaphosphoric acid, etc., which are covered on the surface of the resin to promote the carbonization of the plastic surface to form a carbon film. The polymetaphosphoric acid is covered in a viscous liquid state on the surface of the plastic. The solid or liquid membrane prevents the escape of free radicals and keeps out oxygen.

In addition, PFRs are also a free radical scavenger. Using mass spectrometry technology, it was found that any phosphorus-containing compounds have PO· formed when the polymer is burned. It can combine with the hydrogen atoms in the flame area to suppress the flame.

Flame retardant mechanism of PFR [1]

Advantages and Applications

• Most of the organophosphorus flame retardants have the advantages of low smoke, non-toxicity, low halogen, and no halogen, which are in line with the development direction of flame retardants.
• PFRs have been paid attention to because of their dual functions of flame retardant and plasticization, rich raw material resources and low cost, and have good development prospects.
• Organophosphorus products are mostly oily and are not easily added to polymers during processing, so they are mostly used in polyurethane foam, soft PVC, transformer oil, cellulose resin, natural and synthetic rubber.
• Other application fields of PFRs include engineering plastics, copper clad laminates and fire-retardant coatings.
• In addition, most phosphate ester flame retardants are easily hydrolyzed and biodegradable, and will not encounter the problems of environmental persistence and bioaccumulation during use.

Research Information

Flame Retardant Polymer Nanocomposites

Combining nanomaterials with different geometries with conventional flame retardants, either chemically or physically, can enable the resulting polymer nanocomposites with tunable flame retardancy and mechanical properties. For example, C₆₀ is used in PP in combination with a P/N-containing intumescent flame retardant (IFR) for better thermal and flame retardancy in a research. The presence of PDBPP precludes the aggregation of C₆₀ particles and facilitates the dispersion of C₆₀-d-PDBPP in the PP matrix. The improved fire performance is due to the radical trapping effect of C₆₀ and the formation of a dense carbon layer by PDBPP during combustion. [2]

Schematic representation of dendrimer-like oligomeric intumescent flame retardant bridged with C₆₀, C₆₀-d-PDBPP [2]

References

1. Maria M. Velencoso, et al. (2018). "Molecular Firefighting—How Modern Phosphorus Chemistry Can Help Solve the Challenge of Flame Retardancy," Angewandte Chemie International Edition 57(33), 10450-10467.
2. Ping'an Song, et al. (2009). "Fabrication of dendrimer-like fullerene (C₆₀)-decorated oligomeric intumescent flame retardant for reducing the thermal oxidation and flammability of polypropylene nanocomposites," Journal of Materials Chemistry 19, 1305-1313.