Deformation and thermal resistance study of aerogel blanket insulation material under uniaxial compression

Abstract

Aerogel based composite insulation materials have very low thermal conductivity (∼0.016 to ∼0.040 Wm−1K−1). Aerogel blankets are flexible; however, compressive loads may affect their thermal resistance due to their porous nature. In this paper, the thermal resistance and mechanical deformation of aerogel blankets were studied under compressive mechanical loading. The R-values of two types of commercially available aerogel blankets (Cryogel®Z and ThermalWrap™) were measured using a heat flow meter (HFM) under compressive loads up to 8kPa. Additionally, a mechanistic analytical model was developed to predict the deformation of aerogel blankets using their microstructural properties, including average fiber diameter, particle diameter and porosity. The bending of fibers was considered as the main deformation mechanism at the unit cell level, and the overall blanket deformation was calculated from the summation of the deformations of all the unit cells. The stress-strain relationship was verified using the results of the experimental studies conducted with a HFM and a thermomechanical analyzer (TMA). The maximum decrease in thickness was 20% for 8mm ThermalWrap™ and the maximum change in R-value was a 10% increase with compression observed for a 10mm Cryogel®Z. The results indicated that aerogel blankets remain remarkably effective thermal insulation materials under compression. Even after 20 compression-decompression loading cycles, the reduction of thermal conductivity was ≤5%, and the permanent deformation was ≤6%.