Glass fiber-reinforced intumescent flame-retardant systems in extreme fire conditions—part 2: Burn-through testing and modeling

The article assesses the fire barrier capability of a glass-reinforced intumescent flame retardant system under burn-through conditions. The material is a glass fiber-reinforced intumescent flame retardant polypropylene. The experimental evaluation involved a burn-through test close to the UL2596 standardized test (without grit) for assessing Electrical Vehicle battery protective materials under thermal runaway. The backside time/temperature curves demonstrated the ability of the intumescent material to withstand for 30 min without burn-through. Numerically, a three-dimensional pyrolysis model, including mass and energy conservation principles, heat transfer equations in porous media, and a moving boundary condition (expansion rate) to simulate the thermal expansion of an intumescent material, was implemented. The comparison between the model and experiments showed a good prediction. A parametric study on critical parameters, including emissivity, convective heat coefficient, gas mass diffusion coefficients, and flame heat flux, provided a coherent description of the barrier properties of the material as analyzed by the numerical model.