Radiative Properties of Fiber-Reinforced Aerogel: Theory Versus Experiment

This paper presents a theory and its validation by experiment for the radiative properties of high-porosity silica aerogels that contain randomly oriented and uniformly dispersed fibers. The formulations for the fiber radiative properties are based on fundamental principles, for which parameters defining the material composition are the only required inputs. The predicted spectral transmittance and reflectance for collimated irradiation from the solution of the radiative transfer equation are compared with the measured values. The validity of the theoretical model is established by the good agreement between the predictions and experimental data for various specimens that contain different fiber types, fiber and aerogel solid volume fractions, and specimen thicknesses.