Lightweight, low-shrinkage and high elastic poly(butylene adipate-co-terephthalate) foams achieved by microcellular foaming using N2 & CO2 as co-blowing agents

Abstract

Poly(butylene adipate-co-terephthalate) (PBAT) is considered one of the most promising environment-friendly polymers due to its recognized biodegradability and irreplaceable mechanical properties. Microcellular foaming can further endow PBAT with more functional performance, such as high elasticity, sound and thermal insulation. However, the preparation of PBAT foams generally exhibits serious shrinkage problems, which results in a low and unstable expansion ratio, poor performance, and dramatically limits its wide applications. In this work, the microcellular foaming with N2 & CO2 as co-blowing agents was designed to address the shrinkage problem effectively. Thanks to the N2 & CO2 co-blowing agents, PBAT foams with a high expansion ratio of 14.9-fold and a restricted shrinkage of less than 6% were produced by using microcellular foaming. The results indicate that introducing N2 & CO2 as co-blowing agents can not only stabilize the cellular structure but also restrict the shrinkage of cell walls. More importantly, the prepared PBAT foams exhibited outstanding compressive properties with a strength of 0.17 MPa, and superior resilience with an energy loss coefficient of 12%. Therefore, it is demonstrated that the microcellular foaming with mixed blowing agents provides a suitable strategy to solve the shrinkage of foams, thus exhibiting admirable prospects for the mass production of biodegradable polyester foams.