Continuous Blending Approach in the Manufacture of Epoxidized Soybean‐ P lasticized Poly(lactic acid) Sheets and Films

A single‐step processing system in which an extruder and a peristaltic injector pump attached in tandem was developed for continuous and accurate incorporation of epoxidized soybean oil (ESO) into a poly (lactic acid) (PLA) matrix in order to enhance the flexibility and toughness of PLA sheet and film. The impact strength and the ductility of plasticized sheets produced using this system significantly increased with the ESO content; and the brittle‐to‐ductile transition occurred in the range of 5–10 wt% ESO content. This toughening capacity of ESO as a plasticizer was attributed to its partial miscibility with the matrix. In contrast, both the tensile strength and the modulus of the sheets decreased with increasing ESO content due to the plasticization effect, which induced a decrease in the glass transition temperature. Additionally, the plasticization of PLA film with ESO did not affect its heat sealability during flexible pouch manufacturing as indicated by the burst pressure and the seal strength, which remained unaffected by the addition of plasticizer, irrespective of the sealing temperature studied.