Opacification of PIR Foams to enhance Thermal Resistivity

The development of polyisocyanurate (PIR) foam insulation has been appealing due to the extensive application prospects in buildings and the construction industry for thermal insulation and energy efficiency owing to its low thermal conductivity.Current PIR rigid foams have thermal resistivity (R-value) on average 5.5-6.5 h.ft 2 F/BTU that could be further improved by diminishing the heat transfer through the foam matrix.Additionally, radiative heat transfer accounts for up to 40% of total heat transfer in PIR foams.Reduction of the radiative transfer through the closed-cell foam is a suitable strategy for additional improvement of the insulating performance of PIR foams.Therefore, introduction of opacifiers, which can scatter or absorb the infrared, can lower the IR transmittivity diminishing the heat transfer and improving the thermal insulation performance.In this study, three opacifiers were introduced to the PIR foam matrix and their thermal performance was evaluated.It was shown that the addition of even a small amount of opacifier can reduce the thermal conductivity of the foam, while also having a beneficial effect on its density and closed-cell distribution.The present study then constitutes a useful tool for selecting appropriate foam aids in view of improving the insulation performances of low-density PIR cellular foams.