Continuous Blending Approach in the Manufacture of Epoxidized Soybean- Plasticized Poly(lactic acid) Sheets and Films Shalini Vijayarajan, Susan E. M. Selke, Laurent M. Matuana* 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. 0 10 20 30 40 50 60 0 5 10 15 20 25 Impact strength (J/m) ESO content (wt%) 1. Introduction Petroleum-based polymers have served mankind in nu- merous ways and are widely used in many applications in the United States. However, the continued increase in oil prices, U.S. dependency on foreign oil and environmental concerns have led to a growing interest in bio-based plastics. [1] Replacing petroleum-based polymers with natural bio-based polymers obtained from renewable resources, which can be biodegraded, could be an attractive alternative for a sustainable environment. [2,3] The most common biodegradable polymers are the aliphatic poly- esters such as poly (lactic acid) (PLA), polyglycolic acids, polycaprolactone, and polyhydroxybutyrate. Among these polymers, PLA obtained from corn and sugar beets is commercially gaining a lot of interest because of its relatively high modulus, reasonable strength, thermal plasticity, excellent flavor and aroma barrier capability, good heat sealability, and easy processing. [4,5] Despite these attractive properties, PLA has relatively few commercial applications, concentrating mainly in textile and specialty biomedical niches such as sutures and drug delivery devices. [6,7] Additionally, it is being used as a commodity polymer for packaging food and consumer goods where the physical properties of PLA make it suitable for manufacture of rigid containers and bottles. However, the widespread applicability of PLA in flexible sheets and L. M. Matuana, S. Vijayarajan, S. E. M. Selke School of Packaging, Michigan State University, East Lansing MI 48824, USA Fax: (517) 353 89991; E-mail: matuana@msu.edu Full Paper 622 ß 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim DOI: 10.1002/mame.201300226 Macromol. Mater. Eng. 2014, 299, 622–630 wileyonlinelibrary.com