Thermal and mechanical properties of polyurethane composites filled with thermally expanded hollow microspheres

Polyurethane (PU) composites with various porosities and spherical pore structures were prepared using thermally expanded hollow thermoplastic microspheres. Thermal and mechanical properties of PU composites were mostly governed by the amount of porosity. The measured thermal conductivity of PU composites was estimated using theoretical models, proving the formation of spherical pore structures (ε ≈ 1) in PU matrix and serving as an internal porous material (EMT model < k < parallel model).