Compressive behavior and thermal conductivity-density correlation of expanded polystyrene thermal insulators

Expanded polystyrene (EPS) is a rigid cellular plastic material with an air-filled closed cellular structure manufactured by moulding beads or granules of expandable polystyrene or one of its copolymers. EPS is a good thermal insulator and is therefore often used as thermal insulation materials in buildings. One of the most important factors in selecting thermal insulation products for building applications is thermal conductivity. Other important parameters are water vapour transmission properties, water absorption, and mechanical properties including compressive stress at 10% deformation, etc. Determination of some of these properties is a difficult task and time-consuming. Density determination is a simple, fast, and inexpensive procedure. Once a relationship between these properties and density was established experimentally, measuring the density-related value of some of these properties can be estimated with a good approximation. In this paper, the relationship between compressive stress at 10% deformation and thermal conductivity with the density of expanded polystyrene (EPS) is studied. Tests for determination of density, thermal conductivity, and compressive stress at 10% deformation of domestic EPS panels were conducted on 209 samples. Experimental results showed that thermal conductivity decreases non-linearly with increasing EPS density. On the other hand, compressive stress at 10% deformation increases linearly with the increase of EPS density.