Manufacturing High-Performance Polylactide by Constructing 3D Network Crystalline Structure with Adding Self-Assembly Nucleator

For the inherent brittleness and poor heat-resistance, deformation has been an obstruction to the large-scale application of poly(l-lactic acid) (PLA); simultaneously strengthening and toughening PLA is intensively desirable. This work demonstrates an innovative method to realize the remarkable strength, toughness, and excellent heat-resistant deformation in a PLA composite by constructing a 3D network crystalline structure with the help of fibers self-assembled by tetramethylenedicarboxylic dibenzoylhydrazide (TMC-300). The 3D network crystalline structure is characterized by the interweaved "dendritic" crystals and the interlocked PLA lamellae in the "dendritic" crystals, which are constructed by branched fiber self-organized by TMC-300 and the PLA lamellae growing perpendicularly to TMC fibril. Because of the 3D network's crystalline structure, the tensile strength, Young's modulus, notch impact strength, and the heat-distortion temperature of PLA composite are 61.81 MPa, 1.57 GPa, 4.18 kJ/m2, and 163 °C. Furthermore, with the higher crystallinity and the stronger interlocked PLA lamellae forming a more completed 3D crystal network, the tensile strength and impact strength of the annealed PLA composite improve to 65.33 MPa and 5.87 kJ/m2 with an increase of 21.8% and 1.56 times, compared with pure PLA. This work provides a new industrially scalable method of manufacturing high-performance PLA with potential substitute applications for engineering plastics.