Ultrahigh compressive strength and heat resistance of polystyrene/polyphenylene oxide foams of supercritical carbon dioxide foaming

Abstract Polystyrene (PS) foam materials are lightweight, but suffer from poor compressive strength and heat resistance, among other problems, which limit their application. Herein, a method for preparing PS foam with high compressive strength and high heat resistance using supercritical CO 2 is proposed. PS/polyphenylene oxide (PPO) blends were prepared using a corotating intermeshing twin‐screw extruder. The results showed that PPO exhibited excellent molecular‐level compatibility with PS, which substantially improved mechanical properties and heat resistance of PS. Foam samples of PS/PPO blends with the same expansion ratio were prepared via batch foaming experiments, and the compressive strength of different foams was determined at different temperatures. At room temperature, the compressive strength of the PS/PPO‐30% foam increased by 173% compared with pure PS foam. As the testing temperature increased from 30 to 120°C, the compressive strength of pure PS foams decreased rapidly. Nevertheless, PS/PPO foams maintained high compressive strength at high temperatures.