Prediction of thermal conductivity for polyimide nanofiber aerogel based on three 3D FEM models

Abstract

Polyimide (PI) nanofibrous aerogels (NFAs) have garnered significant attention for their exceptional mechanical and thermal properties, making them promising materials for heat insulation applications. However, there is a lack of comprehensive research on heat transfer of PI NFAs on the modeling and prediction. Therefore, three modified unit cells with the features of PI NFA backbone were constructed for the finite element simulation. Subsequently, the comparisons of our results with experimental data from available literature were conducted. It indicated that the cubic unit cell fitted well with the experimental values when the density was lower than $50\mathrm{kg}/m^3$ , while the Weaire–Phelan unit cell demonstrated good agreement when the density was higher than $50\mathrm{kg}/m^3$ . A series of parametric studies were performed and indicated that the thermal conductivity is proportional to the nanofiber diameter, whereas inversely proportional to the pore size and porosity. Our research will provide novel insights to the selection of parameters for industrial manufacturing of thermal insulation materials in aerospace, energy, protection, etc.