Development of thermally conductive thermoplastic polyurethane composite foams via CO2 foaming-assisted filler networking

In this work, thermoplastic polyurethane (TPU)-hexagonal boron nitride (hBN) composite foams have been fabricated by physical foaming processes using carbon dioxide (CO2) as the blowing agent. Parametric studies were conducted to investigate the effects of saturation pressure, foaming temperature, and post-foaming elastic recovery on the composite foam's morphology and effective thermal conductivity. It was found that foaming-induced filler alignment and post-foaming elastic recovery of TPU synergistically facilitated the formation of interconnected thermally conductive filler network in TPU matrices. This represents a novel processing technique to fabricate TPU-hBN composite foams with enhanced effective thermal conductivity.