High Compressive Strength Branched Polyamide 11 Foams: Reinforcement Effect of Nylon Elastomer and Structural Optimization

ABSTRACT Polyamide 11 (PA11) has gained wide interest as a bio‐based material with a wide range of uses, but its application to foams is challenged by issues such as low melt strength, poor foamability, and a narrow foaming window owing to its linear molecular chain structure. Here, PA11 is modified with differing amounts of the epoxy chain extender ST‐CE37B (ST) and thermoplastic elastomer Pebax MH2030 (MH2030) as a toughening agent to improve its foaming behavior and other properties. PA11 sheets containing varying concentrations of ST (0%–1%) were prepared as raw materials. Samples were subjected to constant‐temperature impregnation in a supercritical CO 2 environment at specific temperatures for 1 h to ensure complete melting and gas saturation, realizing foaming. The addition of 0.75 phr ST and 15 phr MH2030 represents the optimal composition, which improves the expansion ratio of PA11 by 64.36% and increases the impact strength, tensile strength, and compressive strength by 112.64%, 10.02%, and 238.57%, respectively. Based on these findings, a controllable foaming process for PA11/ST/MH2030 blends is successfully demonstrated using supercritical CO 2 .