Lightweight and high performance nano-cellular poly(lactic acid)/poly(3-hydroxybutyrate-co-4-hydroxybutyrate) foams characterized by high volume expansion ratio

An efficient method was developed to fabricate nano-scale poly(lactic acid) (PLA) foams with high volume expansion ratio (VER) aiming at optimizing their properties and cost-effectiveness. The introduction of chain extender ADR (1 wt%) provided enhanced melt strength maintaining cell growth, which created conditions for high value of VER during foaming. The appropriate amount of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB) promoted the crystallization performance and melt strength of samples, which not only facilitated local adsorption of CO 2 and bubble nucleation but also effectively avoided the excessive growth of cells. The impacts of P34HB and ADR as well as foaming temperature were systematically investigated to obtain the optimum conditions for preparing nano-foams with high VER. It could be concluded that the composite foams possessing optimal cell structures were prepared under 113 °C with 3 wt% P34HB content. The foams exhibited an exceptional combination of cell diameter approaching 150 nm, cell density achieving 2.5×10 15 cells/cm 3 , and VER reaching 4.6, exceeding the results reported in existing literatures. The referred foams displayed excellent compression behaviors and superior thermal insulation performances. Generally, the foams fabricated in this work would show broad application prospects in various fields for their outstanding nano-structure and VER. • Bio-based and bio-degradable composite foams were successfully fabricated. • P34HB and ADR were introduced to help fabricate nano-scale PLA foams with high VER. • The cell size approximated 150 nm, the VER approached 4.6, and the cell density reached 2.5×10 15 cells/cm 3 . • The high VER and nano-cells endowed PLA foams with cost-effectiveness and excellent properties. • The foams exhibited outstanding performances of compression and thermal insulation.