The Characterization of Thin Layers of Cellular Plastic Insulations

Abstract

An investigation has been carried out to characterize thin layers of cellular plastic insulations. The thin layers were prepared from the cross-section of six cellular plastic insulations which included the gas-filled closed cell phenolic, iso cyanurate, urethane, and extruded polystyrene foams. For companson, an expanded polystyrene board was also included. In the study the apparent thermal conductivity and the foam bulk density of the test specimens were accurately measured. The ap parent thermal conductivity of all test specimens was measured employing a Heat Flow Meter apparatus. The apparent thermal conductivity of the full board speci mens both with and without the presence of the facer material was first measured. Each board specimen was then sliced into 5-mm thick thin layers with a horizontal band-saw cutting device. The apparent thermal conductivity of each thin layer was then individually measured. The thin layers for each foam insulation were also stacked together as a single test unit and remeasured. Measurements showed that a significant variation in the apparent thermal conductivity and in the foam density of each thin layer for each foam insulation was observed depending on the location of the layer in the cross-section of the board in which the specimen was prepared For all gas-filled foam insulations, thin layers near the surface displayed lower apparent thermal conductivity and higher density values; whereas thin layers in the centre re gion showed higher apparent thermal conductivity and lower density values. Based on the measured results, it was possible to demonstrate a graphical correlation be tween the thermal property and the physical property parameters.