Effect of pore size distribution on compressive behavior of moderately expanded low‐density polyethylene foams

We investigated the effect of the pore size distribution on the compressive behavior for moderately expanded elastic polymer foams. Unlike well‐expanded foams, moderately expanded foams have heterogeneous cellular structures and their mechanical properties can depend on the heterogeneity of cellular structures. To clarify the effect of the pore size distribution on mechanical properties, we prepared a series of low‐density polyethylene (LDPE) foams with different pore size distributions and relative densities as models of moderately expanded elasitc polymer foams. We performed the microscope observations and the uniaxial compression tests of the moderately expanded LDPE foams. The compressive behavior of a foam was primarily determined by the relative density, but we found that the compressive behavior also depends on the pore size distribution, especially in the collapse region. In the collapse region, the compressive stress–strain curves showed clear dependence on the heterogeneities of cellular structures. The broader cell distribution resulted in the stronger strain dependence of the stress in the collapse region. We show that we can reasonably predict the compressive stress–strain curves from the pore size distributions. POLYM. ENG. SCI., 59:510–518, 2019. © 2018 Society of Plastics Engineers