The Effects of Silane-Modified Hollow Silica Nanofillers on Thermo-Mechanical Properties of Rigid Polyurethane Foam

This study explores the enhancement of rigid polyurethane foams (RPUFs) by incorporating silane-modified hollow silica (m-HS) to improve insulation and mechanical properties. Three silane coupling agents—HMDS, APTES, and AAPS—were used to modify hollow silica, which was then added to RPUFs at concentrations of 0.5–5 wt%. RPUFs with 1.0 wt% APTES-HS showed a 64.6% increase in compressive strength (2.24 ± 0.17 MPa) compared to the control. While thermal conductivity improvements were unclear in foams due to structural variability, non-foam polyurethane blocks (PUBs) were used to assess insulation performance. PUBs with 5.0 wt% APTES-HS exhibited a 37.3% reduction in thermal conductivity (175 ± 38 mW/mK). These results indicate that silane surface modification of hollow silica enhances dispersion stability and contributes to better mechanical and thermal performance in polyurethane-based materials, suggesting their promise as high-performance construction materials.