A Pressure-Volume Apparatus to Measure the Effective Thickness of Cellular Plastic Test Specimens

ABSTRACT: Thin specimens of cellular plastic insulations are used in thermal re-sistance and gas diffusion property measurements. It is known that several cells on the surfaces of the test specimens are destroyed during specimen preparation. Hence the effective thickness of the test specimen differs from the geometrical thickness and proper corrections are to be made for the thickness of the destroyed surface layers before other properties are calculated. This note presents an apparatus, its operating principles and an experimental pro-cedure to determine the thickness of destroyed surface layers of cellular plastic insula-tion test specimens