Enhanced mechanical property and thermal insulation of modified rigid polyurethane foams by few surface-functional silica aerogel

Silica aerogel (SA) was functionalized by γ-amino propyl triethoxy silane (APTES) with long chain amino groups, and this surface-functional SA was filled into rigid polyurethane (PU) foams to enhanced mechanical property and thermal insulation. It was proved that the active functional groups and different content of SA (0.3, 0.5, 0.7 and 0.9 wt%) played important roles in controlling cellular structure of PU foams. The results of the scanning electron microscopy (SEM) and water absorption showed that the surface-functionalized SA made the cell uniformly and reduced the number of damage cells. The surface-functionalized SA had a positive effect on the hardness and density of the foams. Moreover, the thermal conductivity of PU foams was reduced by 17.60% and the compressive strength was increased by 43.27% at 0.5 wt% filler of surface-functional SA. The active functional groups (amino groups) of surface-functional SA could take place PU foaming reaction and enhance the interactions and compatibility between SA and matrix. Thus, these foams with small amounts of filler would find vast applications in the thermal insulation sectors.