Flame retardant finish - Fire Proof
Flame Retardant finish - part-2.
Function of a Flame Retardant:
Flame retardants are chemicals are applied to fabrics to inhibit or suppress the combustion process. They interfere with combustion at various stages of the process e.g. during heating, decomposition, ignition of flame spread. Fire is gas phase reaction. For a substance to burn, it must become a gas. As with any solid, a textile fabric exposed to a heat source experiences a temperature rise. If the temperature of the source (either radiative or gas flame) is high enough and the net rate of heat transfer to the fabric is great, pyrolytic decomposition of the fiber substrate will occur. The products of this decomposition include combustible gases, non combustible gases and carbonaceous char. The combustible gases mix with the ambient air and its oxygen. The mixture ignites, yielding a flame, when its composition and temperature are favorable. Part of the heat generated within the flame is transferred to the fabric to sustain the burning process and part is lost to the surroundings.
Mechanism of Flame Retardancy
Flame retardant systems for synthetic or natural polymers can act physically and/or chemically by interfering at particular stages of burning
By cooling Endothermic processes triggered by the flame retardants cool the substrate.
By forming a protective layer: The heat transfer is impeded, fewer pyrolysis gases are evolved, and the oxygen is excluded.
By dilution.: Substances, which evolve inert gases on decomposition, dilute the fuel in the solid and gaseous phases. The concentrations of combustible gases fall under the ignition limit.
Reaction in the gas phase: The free radical mechanism of combustion processes which takes place in the gas phase could be interrupted by flame retardants.
Reaction in the solid phase: One mechanism is the accelerated breakdown of polymers.