Bio-based poly(trimethylene terephthalate) (PTT) and poly(ether esteramide) (PEEA) blends were prepared by melt processing with varying weight ratios (0-20 wt %) of ionomers such as lithium-neutralized poly (ethylene-co-methacrylic acid) copolymer (EMAA-Li) and sodium-neutralized poly(ethylene-co-methacrylic acid) copolymer (EMAA-Na). The blends were characterized by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), polarized light microscopy (PLM), and transmission electron microscopy (TEM). DSC and PLM results showed that EMAA-Na increased the crystallization rate for PTT significantly, whereas EMAA-Li did not enhance the crystallization rate at all. Specific interactions between PEEA and ionomers were confirmed by DSC and TEM. Electrostatic performance was also investigated for those PTT blends because PEEA is known as an ion-conductive polymer. Here, we confirmed that both sodium and lithium ionomers work as a synergist to enhance the static decay performance of PTT/PEEA blends. Morphological study of these ternary blends systems was conducted by TEM. Dispersed ionomer domains were encapsulated by PEEA, which increases the interfacial surface area between PEEA and the PTT matrix. This encapsulation effect explains the unexpected synergy for the static dissipation performance on addition of ionomers to PTT/PEEA blends. This core-shell morphology can be predicted by calculating spreading coefficient for the ternary blends. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 119: 2714-2724, 2011