Rate-temperature Superposition in Mechanical Response of A Polymethylene Diisocyanate (PMDI)-based Rigid Polyurethane Foam

摘要

Polymers including polymeric foams are sensitive to both strain rate and temperature. However, due to limitations in experimental techniques, it is difficult to obtain valid stress-strain response of the materials within very large strain-rate and temperature ranges. In this study, we experimentally characterized the compressive stress-strain response of a PMDI-based rigid polyurethane foam with a density of 0.31X10~(3) kg/m~(3) by using the regular and long split Hopkinson pressure bars (SHPBs) and conventional testing frame (MTS). The stress-strain data were obtained in the strain-rate range from 10~(-2) to 10~(3) s~(-1) at room temperature and in the temperature range from 219 to 347 K at the same strain rate of 3X10~(3) s~(-1). Based on the experimental data, a strain-rate-temperature superposition relationship for the yield strength of the PMDI-based polyurethane foam was developed. This rate-temperature superposition can be used to predict the mechanical response of the foam material at various strain rates or temperatures beyond experimental conditions.