Fabrication of wrinkled thermoplastic polyurethane foams by dynamic supercritical carbon dioxide foaming

Precise control and regulation of the cell structure in supercritical CO2 (scCO(2)) foaming is the key to boost the performance and extend the application of polymer foams. In this work, dynamic scCO(2) foaming method is proposed to fabricate thermoplastic polyurethane (TPU) foams with unique wrinkly structures by introducing a continuous scCO(2) flow field during scCO(2) saturation. The scCO(2) flow field applied on the TPU matrix generated intramolecular stress and resulted in the formation of wrinkles on the surface of cells. The structure of wrinkles was controlled by pivotal processing factors including foaming temperature, pressure, scCO(2) flow rate, and scCO(2) flow time. Attributing to the wrinkly structure, the wrinkled foams possessed superior compressive modulus, strength, recoverability, and energy absorption performance than conventional TPU foams, which make them a promising material for buffering and energy absorption applications. The dynamic scCO(2) foaming method opens avenue for scCO(2) foaming process involves dynamic field.

Automated summary

A dynamic scCO2 foaming method was proposed in this study to fabricate TPU foams with unique wrinkly structures, which possessed superior performance for buffering and energy absorption applications. The controllable wrinkly structure was achieved by regulating key processing factors, indicating a promising avenue for scCO2 foaming process involving dynamic fields.