Mechanically Robust Polylactide Fibers with Super Heat Resistance via Constructing in situ Nanofibrils

All-PLA fibers with excellent comprehensive performance and recycling convenience are realized efficiently. High molecular weight poly(D-lactide) (HPDLA) is incorporated into poly(L-lactide) (PLLA) matrix to construct in situ nanofibrils structure by taking advantages of the microphase separation between HPDLA and PLLA. The tensile strength of HPDLA/PLLA composite fibers (HDL-8) is enhanced from 2.1 cN/dtex of neat PLLA-8 fibers up to 2.9 cN/dtex. Its boiling water shrinkage (BWS) and shrinkage in hot air (HAS) significantly decrease to 7.8% and 2.8%, respectively. The abundance of in situ nanofibrils creates a grille-like structure that is crucial for both heat and hydrolysis resistance. More strikingly, a hybrid shish-kebab structure induced by the in situ nanofibrils serves as a mechanical reinforcement. This work paves a new way for heat resistance and self-reinforcement modification of PLA materials.