Loss of Blowing Agents from Expandable and Expanded Polystyrene

Abstract

A set of expandable polystyrene (PS) beads of different sizes containing mixed blowing agents (n-pentane and i-pentane) with different compositions was prepared and processed in the standard way. Non-expanded PS beads, pre-expanded PS beads and the final PS foams were exposed to air at room temperature for more than 4000 hours and the weight losses due to volatilisation of the blowing agent (LOBA) were followed. Effective diffusion coefficients of n-pentane and i-pentane in PS's were determined from initial parts of LOBA kinetic isotherms. Experimental data were compared with predictions based on the diffusion model.