Bimodal polystyrene/particle foam by extrusion foaming

Extrusion foaming using supercritical carbon dioxide (CO₂) as the blowing agent is an economically and environmentally benign process. However, it is difficult to control the foam density and maintain the thermal insulation performance. In this study, the extrusion foaming process of bimodal polystyrene foams was investigated by using CO₂ as the blowing agent and water as the co-blowing agent. The results show that when water carried by activated carbon (AC) is used as the co-blowing agent and clay as second additive, the cell structure of produced foam is the bimodal characteristic. Compared to the extruded foam without water as co-blowing agent, the bimodal foams exhibit better thermal insulation property and compressive performance.