Low-shrinkage biodegradable PBST/PBS foams fabricated by microcellular foaming using CO2 & N2 as co-blowing agents

•A serious of low-shrinkage biodegradable PBST/PBS foams were fabricated with CO2 & N2.•The presence of PBS could play the role of heterogeneous nucleating agent.•The improvement of non-thermal crystallization and mechanical properties could alleviate the shrinkage process of foams.•Microcellular PBST/PBS foam with a stable expansion ratio of 10.6-fold was achieved with the co-blowing agent of CO2 & N2.