Polyamide 66 Microcellular Foams Enabled Superior Compressive Strength, Heat Resistance, and Thermal Insulation

ABSTRACT Polyamide 66 (PA66) is known for its outstanding mechanical strength, thermal resistance, dielectric properties, chemical resistance, and processability, making it a highly attractive material for applications in electronics, automotive, and aerospace engineering. The development of microporous PA66 foams via scalable processes enables lightweight structural design while addressing increasing demands for high‐temperature performance. However, the high foaming temperature, low melt strength, and narrow foaming window of PA66 hinder its broader utilization. In this study, we propose a scalable strategy to fabricate high‐performance CEPA66/polytetrafluoroethylene (PTFE) composite foams by inducing in situ fibrillation of PTFE under complex flow fields, followed by supercritical CO 2 foaming. The CE/PA66 composite material was obtained by melt chain extension modification using the epoxy‐based chain extender CE as the raw material and then compounded with PTFE via twin‐screw extrusion to obtain CEPA66/PTFE composites. These composites were subsequently foamed via a batch process using supercritical CO 2 . The resulting foams exhibit a uniform and dense cell structure, high compressive strength (0.4 MPa, foam density at 75 ± 10 kg/m 3 ), excellent thermal resistance (dimensional change of only 3% after treatment at 150°C under a 100 g load for 2 h), and low thermal conductivity (0.047 W/(m·K)). This strategy offers an effective approach for the scalable production of high‐performance microporous PA66 foams and provides a new pathway for developing structural materials that combine low weight with excellent thermal resistance and insulation performance.