Preparation of Supertough Polylactide/Polybutylene Succinate/Epoxidized Soybean Oil Bio-Blends by Chain Extension

Poly(lactic acid) (PLA) was toughened using ductile biodegradable poly(butylene succinate) (PBS) and biobased epoxidized soybean oil (ESO). A reactive reagent (Joncryl ADR 4370 S) was introduced for preparing reactive compatibilized bio-blends by melt-processing in situ. The compatibility, rheology, crystallization, mechanical properties, and microstructures of the PLA, PBS, and ESO bio-blends were measured using theoretical compatibility predication, Fourier transform infrared (FTIR) spectroscopy, dynamic mechanical analysis (DMA), dynamic rheological analysis, wide-angle X-ray diffraction (WAXD), mechanical tests, field-emission scanning electron microscopy (FESEM), and optical stereomicroscopy (OM). The introduction of 4370 S induced “graft copolymerization in situ” among PLA, PBS, and ESO and considerably improved the bio-blend compatibility. The PBS and PLA crystal structures were not altered, while the PBS crystallinity reduced in the bio-blends because of chain extensions among the components. The refined PBS particles and evenly distributed ESO drops in the PLA matrix were ascribed to enhanced adhesion and improved compatibility due to the “formation of graft copolymers in situ”. Owing to the combination of ESO and 4370 S, the supertough PLA and PBS bio-blends exhibited a tensile strain at break and notched impact strength above 300% and 30 kJ/m2, respectively.