Effect of Temperature on Long-Term Thermal Conductivity of Closed-Cell Insulation Materials

Abstract

This study examines the isolated impact of temperature on the accelerated aging of closed-cell foam insulation materials. Laboratory aging of closed-cell foams was conducted at three tem-peratures: −10, 23 and 50° C. This was to cover the range of the material’s in-service range within a Canadian climate. Three polyisocyanurate foam and one extruded polystyrene foam insulations were considered in the study. The three polyisocyanurate foam products tested showed significant variability in polynomial functions at lower mean temperatures when newly manufactured; how-ever, these differences were found to diminish over time. Thermal conductivity decreased between 0% and 17% depending on mean temperature following equivalent 5-year aging at 23° C. Aging polyisocyanurate specimens at −10° C was found to decrease rate of change in thermal conductivity by approximately 5% compared to aging at 23° C when measured at a mean temperature of 24° C, while aging at 50° C had a smaller impact. However, at mean temperatures below the beginning of condensation point, there was greater variability in the impact of aging temperature. For the extruded polystyrene, thermal conductivity decreased between 8% and 10% following equivalent 5-year aging at 23° C and displayed a linear relationship with a 23% difference in thermal conductivity between −10° C and 40° C.