Fabrication of polyamide 12T micro‐cellular foams with ultra‐high compressive strength via in situ polytetrafluoroethylene fibrillation using supercritical carbon dioxide foaming

Abstract

AbstractThe development of micro‐cellular foams with ultra‐high compressive strength and high volume expansion ratio (VER) is a challenging task. Herein, polyamide 12T (PA12T) micro‐cellular foams with ultra‐high compressive strength were fabricated via in situ polytetrafluoroethylene (PTFE) fibrillation using supercritical CO2 foaming technology and a chain extender. The resulting branched structure showed considerably improved viscoelasticity and foaming performance, thus improving the cell morphology of the PA12T foam and exhibiting high VER. The PTFE fibrillation network induced melt strength enhancement, crystallization nucleation, and cell nucleation. The branched PA12T foam with 1.5 wt% PTFE exhibited the smallest cell diameter (15 μm) and highest cell density (3 × 109 cells/cm3). The compressive strength of the foam (0.50 MPa under 5% strain) was 70% higher than that of pure PA12T. This research offers an effective method for producing high‐VER PA12T foams with adjustable micro‐cellular structures and excellent mechanical properties.