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 ran domly oriented and uniformly dispersed fibers. The formulations for th e fiber radiative properties are based on fundamental principles, for which parameters defining the material composition are the only requir ed inputs. The predicted spectral transmittance and reflectance for co llimated irradiation from the solution of the radiative transfer equat ion are compared with the measured values. The validity of the theoret ical model is established by the good agreement between the prediction s and experimental data for various specimens that contain different f iber types, fiber and aerogel solid volume fractions, and specimen thi cknesses.