Thermal conductivity aging and mechanical properties of polyisocyanurate (PIR) foams produced with different contents of HFO

Polyisocyanurate (PIR) foam is a thermal insulating material widely used in many industries such as construction, refrigeration, piping/tubing among others. In this research the production, characterization and modeling of the thermal conductivity of PIR foams synthesized with a hydrofluorolefin (HFO 1233zd (E)) as physical foaming agent have been studied. The results have shown that increasing the amount of HFO reduces the density, but the cellular structure is not modified. The relative mechanical properties are the same for the concentrations of HFO considered. In addition, the aging of thermal conductivity as a function of time has been studied in detail. The experimental results have been deeply analyzed using a theoretical model to predict the thermal conductivity The results show that the thermal conductivity and the rate of aging at early stages are reduced for the higher concentrations of HFO. This result has been related to the lower temperature reached during the foaming reaction for higher contents of the physical blowing agent.