Thermal Behavior of Mesoporous Aramid Fiber Reinforced Silica Aerogel Composite for Thermal Insulation Applications: Microscale Modeling

This paper explores the incorporation of aramid fibers, recognized for their high mechanical flexibility and low thermal conductivity (TC), to serve as reinforcing agents within the highly porous aerogel matrix in order to overcome their fragility and weak mechanical structure that impose limitations on their practical utility especially in piping insulation. The thermal properties are determined using a micromechanical modeling approach that considers parameters such as temperature, fiber volume fraction, thermal conductivity, and porosity of the silica aerogel. For specific conditions, including an Aramid fiber radius of 6 microns, a silica aerogel thermal conductivity of 0.017 W.m-1.K-1, and a porosity of 95%, the resulting AFRA composite exhibits an Effective Thermal Conductivity (ETC) of 0.0234 W.m-1.K-1. Notably, this value is lower than the thermal conductivity of air at ambient temperature. The findings are further validated through experimental and analytical techniques. A response surface methodology (RSM) based on Box-Behnken design (BBD) is employed. This approach leads to the development of a quadratic equation intricately relating the key parameters to the ETC of the AFRA. The aim is optimization, identifying target optimal values for these parameters to further enhance the performance of AFRA composites.