Finite difference analysis of thermal response and post-fire flexural degradation of glass fiber reinforced composites coated with carbon nanofiber based nanopapers

In this study, a 1D transient finite difference model was developed to predict the thermal response and post-fire flexural modulus degradation of glass fiber reinforced polyester composites subjected to various levels of heat flux. A carbon nanofiber (CNF) based hybrid nanopaper was coated onto the surface of the composites. The protective nanopaper coating was treated as to impose a temperature boundary condition in the model. A temperature dependent post-fire mechanical property model proposed in an earlier study was implemented with the thermal model in which the porosity and permeability of the material were taken into account. By comparing the post-fire residual flexural moduli, the model prediction showed reasonable agreement with the experimental data and expected physical behaviors. The model numerically demonstrates how the coating of nanopaper helps retain the structural integrity of the composite material, namely, the nanopaper coating leads to a reduction in mass loss, reduced cold side temperature, and eventually improved mechanical property. Furthermore, the parametric study of the model suggested that the porosity of the material has profound influence on the residual moduli of the composites.