Deformation of the rubber domain is due to extensive plastic deformation of the surrounding PLA in view of the heterogeneous stress field involved.
The deformation process can absorb a large amount of energy, contributing to the high toughness.
It is worth noting that the elongated polymeric domain connects with the smooth phase.
Therefore, on the basis of TEM and SEM analysis, we suspect that the smooth phase is the crosslinked NR phase, which forms a net-like structure in the PLA phase.