Fabrication and Characterization of Thermally Insulating Polyurethane-Silica Aerogel Composite for Cryogenic Application

Polyurethane-silica aerogel (PUSA) composites have been synthesized in this study for thermal insulation applications. Silica Aerogel (SA) was synthesized from sodium silicate solution through a standard sol–gel process and ambient pressure drying. Previous research has shown that combining PU with SA in a composite causes brittle fracture at lower temperatures. This study proposes that PU was re-formulated with ethylene glycol (EG) as an antifreeze and chain extender to enhance the mechanical properties. In this experiment, different composites were produced having different SA concentrations (0.5 wt.%, 1.0 wt.%, 1.5 wt.%, and 2.0 wt.%). The glass transition temperature (T_g) of the PUSA composites as conducted by Differential Scanning Calorimetry (DSC) between 0 to -80 ℃ reveals the shift in T_g by as much as 12% with SA addition between 0.5–2.0 wt. %. PUSA composite with 1 wt.% SA demonstrates the highest compressive strength (0.56 MPa), while composite with 1.5 wt.% SA exhibited the lowest thermal conductivity (0.2 W/mK). PUSA composites containing 1.0–1.5 wt.% SA exhibited optimum mechanical strength and thermal insulation properties.