Structure-tunable poly(butylene adipate-co-terephthalate) foams with enhanced mechanical performance derived by microcellular foaming with carbon dioxide as blowing agents

Abstract

Poly(butylene adipate-co-terephthalate) (PBAT) is an advanced environment-friendly polymer that exhibits excellent biodegradability and outstanding mechanical properties. Microcellular foaming can endow PBAT with many admirable properties, which is significant for broadening its applications. Nevertheless, it is still challenging to prepare high-performance PBAT foams with tailored structures due to poor foaming ability. Moreover, the unclear relationships between foaming process, cellular structure, and mechanical properties significantly limit its development and application. In this study, microcellular foaming with carbon dioxide as blowing agents was developed to prepare structure-tunable PBAT foams with enhanced mechanical performance. Firstly, microcellular foaming experiments were conducted under various foaming pressures and temperatures to investigate the dependence of cellular morphology on foaming conditions. Under the investigated foaming conditions, the cell diameter and expansion ratio of PBAT foams can be manipulated in the ranges of 10–100 µm and 1–20, respectively. Furtherly, the dependence of tensile properties and compressive properties on cellular morphology was clarified. Compared with cell diameter, expansion ratio exhibited a much more significant effect on both the tensile and compressive properties of foams. In particular, PBAT foams with a tensile property of 5 MPa and a compressive property of 0.5 MPa were prepared, which possessed a lower density of 0.15 g/cm3. The prepared structure-tunable PBAT foams showed much lower density but obviously enhanced mechanical properties than the PBAT foams reported in literature.