Structure-tunable thermoplastic polyurethane foams fabricated by supercritical carbon dioxide foaming and their compressive mechanical properties

Towards fabricating structurally tunable TPU foams with improved mechanical properties, the foaming behavior of TPU in two foaming routes including H-foaming and C-foaming were investigated. In H-foaming, foaming took place as raising temperature from low to high levels. In C-foaming, foaming took place as reducing temperature from high to low levels. Foaming temperatures and CO2 pressures were regulated to tailor foam structure. Low density microcellular TPU foams with tunable structures were fabricated. Furthermore, with these structurally tunable TPU foams, the influences of foaming methods and cellular structures on foam's compressive mechanical properties were investigated. TPU foams fabricated by C-foaming showed superior resilience and strength than those fabricated by H-foaming. TPU foams with larger cells exhibited better resilience and strength than those with smaller cells. This study is of great significance in enriching the understanding of both the foaming behavior of TPU and the structure-property relationships of TPU foams. (C) 2019 Elsevier B.V. All rights reserved.