Can aluminum hypophosphite flame retard PUF?

The full name of PUF is Polyurethane Foams, which has good heat and sound insulation, waterproof and moisture-proof, shock resistance, corrosion resistance, etc. However, it is difficult for PUF to be flame retardant. Can aluminum hypophosphite flame retardant PUF? The answer is yes, the flame retardant effect of aluminum hypophosphite on PUF is mainly manifested in the two aspects of free radical capture and carbon layer isolation, the process is more complex, PUF modification can improve the flame retardant effect. The decomposition temperature, particle size, compatibility and other indicators of aluminum hypophosphite have a certain impact on the flame retardancy of PUF system.

The addition of aluminum hypophosphite flame retardant has a great enhancement on the amount of residual carbon, due to the PUF in the combustion process attached to the surface of the carbon content increases, the formation of carbon layer, thus preventing the continuation of combustion, improve the difficulty of thermal degradation of PUF, reduce the rate of thermal degradation. The decrease in the thermal degradation temperature of the material after the addition of the flame retardant may be due to the addition of the flame retardant, which reduces the overall thermal stability of the material. At the same time, we can clearly see that the carbon layer formed after the combustion of the foam with the addition of aluminum hypophosphite flame retardant becomes very dense and uniform. The charcoal layer isolates the external oxygen, prevents heat conduction and protects the unburned part of the lower layer, thus achieving the effect of flame retardancy.

PUF referred to as polyurethane foam, small density, due to the presence of combustible hydrocarbon chain segments, large specific surface area, LOI of about 19%, belongs to the flammable material, high porosity, combustible components, combustion due to the high air circulation and a constant supply of oxygen, flammable and not easy to extinguish itself. When burned, it will decompose and produce a large amount of C0, HCN, etc., so the flame retardant of PUF has strict requirements.

The flame retardant effect of aluminum hypophosphite on PUF is shown in LOI:28% (30% AHP), in which the phosphine generated by AHP plays a key role in capturing the free radicals, generating a strong dehydrating agent metaphosphoric acid, prompting the material surface dehydration into charcoal, and the formation of a charcoal layer covering the surface of the foam can effectively cut off the air, reduce the heat transfer, and improve the flame retardant properties of the material.