Study on the Compressive Deformation Behavior of SAN/EPDM Blend Foams Prepared under Different Process Flow Fields

Acrylonitrile-styrene copolymer/ethylene propylene diene monomer (SAN/EPDM) foams were prepared under an elongational and shear flow. The effects of the process flow field on the rheological properties, cell structure, and compressive strength of SAN/EPDM foams were systematically investigated. The results revealed that the elongational flow significantly enhanced the molecular orientation of the blends, leading to the formation of foams with ellipsoidal cellular structures, whereas shear flow processing induced a bimodal cell size distribution in the prepared blend foams. SAN/EPDM foams prepared under elongational flow showed higher cell density and volume expansion compared with those prepared under shear flow. The compressive properties of the foams were strongly influenced by both the cell structure and compressive direction. Finite element method simulations revealed that the improved compressive performance was attributed to the reduced vesicle diameter along the orientation axis. The highest compressive strength was achieved at 5% EPDM content when compressed perpendicular to the orientation direction.