Effects of high functionality polyol on the structure and properties of rigid polyurethane foam

High performance rigid polyurethane foam (RPUF) has been designed by using hyperbranched polyurethane (HBPU) polyol with high functionality to replace traditional polyol. The influences of different types of polyol on the apparent density and heat deformation temperature of RPUF were studied. The microstructures, including cell structure, cell diameter and distribution, were characterised by SEM. Effects of polyol types on the cell structure of RPUF were discussed. Thermal resistance and thermal stability were measured by the thermal deformation vicat temperature meter and TGA. Thermal conductivity of RPUF was characterised by Hot Disk, and the mechanical properties were also measured. Compared with the RPUFs obtained from commercial polyether polyols, RPUF-HBPU exhibited enhanced thermal resistance. Besides, the compressive strength, flexural strength and tensile strength were up to 4.5, 4 and 3.5 times, respectively, than that of traditional RPUF as well. The as-prepared RPUF-HBPU displayed low thermal conductivity/thermal diffusion and good thermal stability.