Fire Resistance of PTFE-Based Materials Under Radiant Heat Flux Conditions

Radiant heat flux is the main heat transfer form in large-scale fire scenes such as building fires, industrial equipment fires and electrical cabinet fires. Different from direct flame combustion, radiant heat flux relies on thermal radiation to continuously transfer heat to the material surface, causing slow temperature rise, thermal accumulation and gradual pyrolysis of materials. This long-term steady-state heat erosion is more likely to cause hidden fire hazards and delayed combustion failure than direct flame impact. PTFE-based materials, as high-performance fire-resistant materials, have excellent fire resistance under radiant heat flux conditions. Studying their thermal response, pyrolysis behavior and fire resistance stability under different radiant heat flux intensities is crucial for evaluating the fire safety of PTFE materials in actual fire scenes PTFE SHEET.

The excellent fire resistance of PTFE-based materials under radiant heat flux is derived from their ultra-low thermal conductivity and high thermal stability. PTFE has a thermal conductivity as low as 0.24 W/(m·K), which is far lower than most engineering polymer materials. Under continuous radiant heat flux, PTFE materials can effectively block external thermal radiation, slow down internal heat accumulation, and avoid rapid temperature rise and local overheating of materials. In low and medium radiant heat flux environments (10–30 kW/㎡), the surface temperature of PTFE materials rises slowly, no pyrolysis and combustion reaction occurs, and the materials maintain stable structural and performance integrity for a long time, showing excellent passive fire protection ability.

Under medium and high radiant heat flux conditions (30–50 kW/㎡), ordinary polymer materials will rapidly reach the pyrolysis temperature, produce a large amount of flammable gas, and start spontaneous combustion. In contrast, PTFE-based materials have a high pyrolysis initiation temperature, and only slight surface thermal decomposition occurs under continuous radiant heat. The decomposed fluorine-containing active substances can form a thin inert protective film on the material surface, which further reduces the absorption of radiant heat, inhibits the development of pyrolysis reaction, and will not produce sustained combustion and flame spread. Even if local surface carbonization occurs, the internal matrix structure remains intact, and the material still retains basic fire-resistant and insulating properties.

Modified PTFE composite materials show more outstanding fire resistance under extreme high radiant heat flux conditions (above 50 kW/㎡). By adding inorganic heat-insulating fillers and high-temperature resistant components, the composite material further reduces thermal conductivity, improves thermal radiation reflection ability, and prolongs the thermal decomposition induction period. In high-strength radiant heat environments, composite PTFE materials can effectively resist long-term thermal erosion, delay ignition time, reduce combustion heat release rate, and minimize fire spread risk. Industrial PTFE TUBE and composite flame retardant sheets have passed strict radiant heat flux fire tests, and their fire resistance duration and structural survival rate are far higher than ordinary flame retardant plastics and rubber materials.

Compared with other fire-resistant materials, PTFE-based materials have unique advantages in radiant heat flux fire resistance. Traditional fire-proof coatings and organic flame retardant materials are easy to age and fail under long-term thermal radiation, with poor heat resistance stability. Inorganic fire-proof materials have high heat resistance but poor flexibility and processing performance, and are easy to crack and fall off under thermal expansion and contraction. PTFE-based materials integrate low thermal conductivity, high thermal stability, excellent flexibility and structural stability, and can maintain long-term reliable fire resistance under continuous radiant heat flux, which is suitable for complex fire-prone environments such as equipment internal insulation, pipeline protection and closed electrical cabinets.

In actual fire accident simulation tests, PTFE-based materials show excellent anti-radiant heat fire performance. Under long-term high-intensity thermal radiation, the ignition time of PTFE materials is more than 3 times longer than that of ordinary flame retardant polymers, the total heat release is reduced by more than 60%, and the smoke generation is extremely low. This excellent performance can effectively delay the fire spread speed, gain rescue time, and reduce fire loss. With the continuous improvement of industrial fire safety standards, PTFE-based fire-resistant materials will be more widely used in building fire protection, electrical equipment fire prevention, industrial pipeline safety protection and other fields, becoming an important guarantee for industrial fire safety.