Microstructure and thermal characterization of aerogel-graphite polyurethane spray-foam composite for high efficiency thermal energy utilization.

Aerogel is a superinsulating material with an extremely low thermal conductivity (<0.015 W/m·K), high porosity (>99 %), and extremely low density. In this study, a new closed-cell spray polyurethane (PU) foam with aerogel was developed and investigated. In particular, a PU foam with aerogel and graphite (PUAG) was prepared by mixing aerogel for reducing the thermal conductivity of the foam and a small concentration of graphite for improving its flame-retardancy performance. The performance of the prepared PUAG was analyzed via several tests, including density measurements, thermal-conductivity measurements, morphology examination, flame-retardancy evaluation, thermogravimetric analysis, and dynamic heat transfer analysis. A 20 % reduction in the thermal conductivity compared with traditional PU was observed. Additionally, the PUAG exhibited a reduction in the total smoke production and a 10 % reduction in the surface peak temperature.