Plasticization Effect of Poly(Lactic Acid) in the Poly(Butylene Adipate–co–Terephthalate) Blown Film for Tear Resistance Improvement

The mechanical properties and tear resistance of an ecofriendly flexible packaging film, i.e., poly(lactic acid) (PLA)/poly (butylene adipate–co–terephthalate) (PBAT) film, were investigated via a blown film extrusion process. The application of PLA and PBAT in product packaging is limited due to the high brittleness, low stiffness, and incompatibility of the materials. In this study, the effects of various plasticizers, such as adipate, adipic acid, glycerol ester, and adipic acid ester, on the plasticization of PLA and fabrication of the PLA/PBAT blown film were comprehensively evaluated. It was determined that the plasticizer containing ether and ester functionalities (i.e., adipic acid ester) improved the flexibility of PLA as well as its compatibility with PBAT. It was found that the addition of the plasticizer effectively promoted chain mobility of the PLA matrix. Moreover, the interfacial adhesion between the plasticized PLA domain and PBAT matrix was enhanced. The results of the present study demonstrated that the plasticized PLA/PBAT blown film prepared utilizing a blown film extrusion process exhibited improved tear resistance, which increased from 4.63 to 8.67 N/mm in machine direction and from 13.19 to 16.16 N/mm in the transverse direction.