Fig. 1 shows the phase morphology of PLA/EVA (80/20) blends. When the VA content in the EVA copolymer is lower than 70 wt.%, phase separation is observed between PLA and EVA, which is consistent with a previous study [25]. Since PLA is miscible with PVAc, the vinyl acetate segments in the EVA copolymers have a good affinity with PLA matrix.
Therefore, the interfacial properties are improved with an increase in VA content. At low VA content (640 wt.%), the particle size of the EVA is large which can be ascribed
to a high interfacial tension. Moreover, voids due to interfacial debonding between the PLA matrix and the EVA0 particles (LDPE) are observed (Fig. 1a), indicating a weak
interfacial adhesion. In contrast, hardly any phase separation occurs in the PLA/EVA90 blend (Fig. 1e), which is consistent with a single glass transition (Tg = 48 C) of the
blend (the DSC curves are not shown here).