Preparation of biodegradable PBST/PLA microcellular foams under supercritical CO2: Heterogeneous nucleation and anti-shrinkage effect of PLA

•A series of fully biodegradable PBST/PLA blending foams were prepared.•The presence of PLA in PBST could facilitate cell nucleation and open-cell structure formation.•The addition of PLA could effectively solve shrinkage problem of PBST foams.•80/20 blend of PBST and PLA exhibited the highest expansion ratio of 17 without shrinkage.