Characterization of commercial aerogel-enhanced blankets obtained with supercritical drying and of a new ambient pressure drying blanket: Fid-Bau Portal

Characterization of commercial aerogel-enhanced blankets obtained with supercritical drying and of a new ambient pressure drying blanket

Berardi, Umberto

Abstract

Highlights • Aerogel-enhanced blankets obtained with supercritical drying (SCD) are characterized. • Commercial SCD products are compared with a new blanket developed using an APD process. • Products are analyzed using BET surface area, IR spectroscopy, and chemical composition. • SEM and BET surface area analyses help identifying differences in the filaments and structure. • Thermal conductivity values below 0.02 W/mK were found in many aerogel-enhanced blankets.

Abstract Aerogel-enhanced products are often seen as promising materials for providing significant thermal resistance with reduced thickness. In particular, aerogel-enhanced blankets have already shown their effectiveness in several building retrofitting projects. In aerogel-enhanced blankets, a fiber matrix supports the aerogel structure, compensating for the poor mechanical properties of the aerogels. While an increasing body of literature has presented the characterization of specific aerogel-enhanced blankets, no study has so far compared the several commercially-available products. This paper reports the characterization of common aerogel-enhanced blankets produced with supercritical drying (SCD) and of one product produced with ambient pressure drying (APD) by the authors. The different aerogel-enhanced blankets are compared for their bulk density, BET surface area, hydrophilic behavior, chemical composition, and thermal conductivity. IR spectroscopy and contact angle analysis provide insight regarding the hydrophobicity of each blanket. SEM and BET surface area analyses allow to identify structural differences in the blanket filaments and in the binding mechanism of the aerogel to these filaments. The findings provide valuable insight into the differences among products. For example, the thermal conductivity tests confirm the superior performance of aerogel-enhanced blankets compared to traditional insulating materials, but they reveal the temperature dependency of their thermal conductivity and some differences among manufacturer-declared and experimentally-obtained values. The literature review and the experimental comparison between the SCD and APD blankets reveals that only some products are able to achieve extremely low thermal conductivities using APD, with a value around 0.016 W/mK, while blankets using an SCD process show thermal conductivity values lower than 0.02 W/mK more consistently.