Foaming of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/organo-clays nano-biocomposites by a continuous supercritical CO 2 assisted extrusion process

•PHBV/clays nano-biocomposite foams were prepared by a continuous sc-CO2 assisted extrusion process.•The use of diluted PHBV/clays masterbatch prevents thermal degradation while giving good clay dispersion.•Good clay dispersion favours homogeneous nucleation and limits the coalescence of the pores.•Nano-biocomposite foams with porosity up to 50% were obtained.