Epoxidized natural rubber as a renewable compatibilizer for enhancing stereocomplex crystallization in polylactide blends

Epoxidized natural rubber (ENR), a renewable derivative of natural rubber (NR), was investigated as an effective compatibilizer to enhance the crystallization behavior of stereocomplex polylactide (stPLA) blends. Neat stPLA and blends containing NR or ENR (5–20 wt%) were prepared via melt blending. Differential scanning calorimetry showed that ENR exhibited better compatibility with PLA than NR, promoting stereocomplex crystallization while suppressing homocrystalline formation. At 10 wt% ENR, the stereocomplex crystallinity increased to 42.3 %, more than twice that of neat stPLA. Polarized optical microscopy revealed an earlier crystallization onset in ENR-containing blends (∼140 °C) compared with stPLA and stPLA–NR (∼120 °C). Water contact angle measurements indicated enhanced surface hydrophilicity, reaching an optimum of ∼70° at 10 wt% ENR. Non-isothermal crystallization kinetics analysis demonstrated that ENR accelerated crystallization and reduced the activation energy barrier, confirming its role as an effective compatibilizer facilitating stereocomplex crystallization via enhanced miscibility.