A first approach towards investigating the compatibility and phase separation of two polymers is comparing their solubility parameters (d). Two polymers generally show
compatible or even miscible behavior when their solubility parameters are close to each other. An example is PVAc and PLA whose solubility parameters are 9.6 and 9.7 (cal/cm3)1/2 respectively [27]. The solubility parameter of the EVA copolymers varies between the d of LDPE (8.3 (cal/cm3)1/2) [27] and the d of PVAc depending on the composition of
the EVA. Thus, it is possible to tune the compatibility between PLA and EVA by controlling the solubility parameter (i.e. composition) of the EVA copolymers. The compatibility increases with increasing VA content in the EVA copolymer, resulting in a monotonic reduction in EVA particle size (Fig. 1).