Effects of Humidity and Elevated Temperature on the Density and Thermal Conductivity of a Rigid Polyisocyanurate Foam Co-Blown with CCl3F and CO 2

Abstract

Measurements of density and apparent thermal conductivity are pre sented for specimens cut from rigid polyisocyanurate (PIR) foam co-blown with trichlorofluoromethane (CCl 3F) and carbon dioxide (CO2) Eight specimens, nominally 580 by 580 by 27 mm, were prepared from two boards (1.2 by 2.4 m by 50 mm) of foam laminated with permeable facers. Four specimens were placed in an ambient condition of 22°C and 40% relative humidity (RH). The other four speci mens were each placed in one of the following environments: 1) 60°C and < 10% RH; 2) 60°C and 40% RH; 3) 60°C and 60% RH; and 4) 60°C and 75% RH. Mea surements of apparent thermal conductivity at 24°C were conducted over a period of 372 days at approximately 50-day intervals. Curves of specimen mass, volume, density, and thermal conductivity versus time are presented, and the implications of changes in these properties are discussed.