Fabrication of outstanding mechanical performance engineered poly (lactic acid)/thermoplastic poly(ester)urethane in-situ nanofiber composites with a large-scale industrial innovation methodology

As one of the most promising biodegradable materials, poly(lactic acid) (PLA) is seriously restricted by its notorious brittleness and weak heat distortion resistance. Hitherto, the possibility of effectively toughening PLA while simultaneously maintaining high strength and stiffness has hardly been realized on an industrial scale. In this work, an innovative industrial methodology was applied to manufacture high-performance engineered (95x) poly(L-lactic acid)/5poly(D-lactic acid)/xthermoplastic poly(ester)urethane ((95-x)L/5D/xT) nanofiber composites. The in-situ formed TPU nanofibers (TNFs) combined with sterocomplex crystals (SCs) generating synergistic effects significantly improve the crystallization behavior and elasticity of melt. The compatibility between PLA matrix and TNFs in (95-x)L/5D/xT nanofiber composites was significantly reinforced by constructing bundle structures. The bundle structure is composed of rigid PLA hybrid crystals tightly bundled with a handle of oriented TNFs with good interfacial compatibility, bundle structures interlink with each other forming 3D strengthening-toughening bundle structures contributing to the mechanical performance. The notched Izod impact strength of 80L/5D/15T and 75L/5D/20T nanofiber composites prodigiously increase to 74.8 and 98.7 kJ/m2, which is 27.7 and 35.6 times higher than that of neat PLLA. Meanwhile, the nanofiber composites can maintain balanced tensile yield strength, good Young's modulus, and obtain advantaged heat distortion resistance of 1132 MPa at 100 degrees C. Compared with reported PLA/elastomer blends, neat biodegradable plastics, general-purpose and engineering plastics, the efficient industrial-scale manufactured 80L/5D/15T and 75L/5D/ 20T nanofiber composites possessing outstanding mechanical performance of super toughness, balanced strength, good Young's modulus and advantaged heat distortion resistance. It has immense potential to substitute non-degradable petroleum-based engineering plastics as structural materials in harsh environments, thereby reducing CO2 emissions and reducing pollution caused by discarded non-degradable petroleum-based plastics.