Compressive Behavior of Moderately Expanded Low Density Polyethylene (LDPE) Foams

Abstract

We investigated the compressive behavior of moderately expanded low density polyethylene (LDPE) foams. Moderately expanded LDPE foams have polydisperse cell size and wall thickness distributions, both of which are considered to be approximately monodisperse for well-expanded foams The compressive stress-strain curves showed three different regions (the linear elasticity, collapse, and densification regions) which are commonly observed for well-expanded foams. Unlike well-expanded foams, the stress of the moderately expanded LDPE foams in the collapse region was not constant. The relative density dependence of the Young’s modulus and collapse stress was different from that for well-expanded foams. These properties would originate from the polydisperse cell strength distribution. To explain these experimental data, we propose a simple model which incorporates the distribution of the cell strength. Our model showed that the cell strength distribution strongly affects the compressive behavior.