Fabrication of Biodegradable Poly(Lactic Acid) Composites with High Toughness via In Situ Fibrillation Method and Facile Annealing Process

Abstract

Elastomer-toughened biodegradable poly(lactic acid) (PLA) composites have been extensively studied; however, improving the toughening efficiency of elastomers with low costs while maintaining the biodegradability of composites remains challenging. In this work, biodegradable PLA/poly(propylene carbonate) polyurethane (PLA/PPCU) composites with high toughness were successfully prepared by the in situ fibrillation method followed by a facile annealing treatment. The chain extender (CE) was added to alter the viscosity ratio of the dispersed phase to the matrix, thereby tailoring dispersed phase morphology. PPCU fibers were observed when the CE content is greater than 0.5 wt %. Due to the increase in interfacial area, the impact strength increased from 5.1 ± 1.1 kJ/m2 for PLA/PPCU/CE blends with droplet-like dispersed phase morphology to 8.3 ± 1.0 kJ/m2 for PLA/PPCU/CE blends with fibrous dispersed phase morphology. Furthermore, when the CE content was 1.5 wt %, the impact strength of PLA/PPCU/CE blends increased sharply to 30.5 ± 3.9 kJ/m2 after a facile annealing treatment, which could be attributed to the greatly increased interfacial area and interfacial strength. This work provides a viable way to improve the toughness of PLA-based blends without sacrificing their degradability, which will facilitate the large-scale practical application of PLA.