Ternary Synergistic Toughening of Biodegradable Polylactic acid Foams by Elastomer, Rolling and Supercritical Fluid Foaming for Enhanced Anisotropy

Polylactic acid (PLA) is a widely used biodegradable polymer, but its brittleness severely limits its further application. This study explores the preparation of anisotropic polylactic acid/thermoplastic polyurethane (PLA/TPU) foam through melt blending with elastomers, rolling, and supercritical fluid foaming (SCF), which substantially enhances the toughness of PLA. Results indicate that the crystallinity and elongation at break of PLA/TPU blend improve with increasing rolling temperature and rolling rate. Notably, at a rolling temperature and a rolling rate of 50%, the elongation at break for the PLA/TPU blends increases from 4.0 to 59.0%. In addition, SCF processing yields an anisotropic, highly oriented, and elongated cell structure within PLA/TPU foam. This cellular architecture further elevates the elongation at break of the rolled PLA/TPU blend to 76.8% and 1820.0%. This research offers a straightforward, environmentally friendly, and scalable method for fabricating high-strength PLA-based foam materials, equipping them with functionalities such as buffering, sound absorption, shock absorption, heat preservation, etc., which is suitable for electronics, home appliances, sports and other fields.