Evaluation of some eco-friendly plasticizers for PLA films processing Raluca N. Darie-Nit ¸  a, 1 Cornelia Vasile, 1 Anamaria Irimia, 1 Rodica Lips ¸a, 1 Maria R ^ ap  a 2 1 “Petru Poni” Institute of Macromolecular Chemistry, Iasi 700487, Romania 2 ICPAO S.A, Medias, Sibiu 551022, Romania Correspondence to: C. Vasile (E - mail: cvasile@icmpp.ro) ABSTRACT: This study was conducted as a first step in order to obtain green materials for food packaging by using an eco-friendly bioplastic, polylactic acid (PLA), and nontoxic plasticizers. Different types of nontoxic biocompatible plasticizers/lubricants, both obtained in the laboratory, as well as commercial ones, were employed to modulate physical and mechanical properties of PLA. Melt compounding by means of a Brabender mixer led to obtaining of homogeneous materials. The incorporation of PLA oligomer, L-lac- tide, poly(ethylene glycol), and epoxidized soybean oil (USE) improved the melt flow and processability, increasing the hydrophilicity of the resulted plasticized PLA systems. USE significantly increased the elongation at break, reduced the glass transition temperature, and increased the PLA chain mobility. VC 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43223. KEYWORDS: plasticizer; thermoplastics; viscosity and viscoelasticity Received 25 August 2015; accepted 12 November 2015 DOI: 10.1002/app.43223 INTRODUCTION Nowadays, the interest in the use of biopolymers in different applications has increased due to their potential to substitute cer- tain synthetic and petroleum-based materials. Also, the develop- ment and application of biocompatible plasticizers/lubricants are increasing in the last decades as a result of stringent regulations imposed on mineral oil-based lubricants with their nonbiode- gradable toxic wastes. However, vegetable oil-based plasticizers/ lubricants have poor performance characteristics such as thermal and oxidative instabilities. Polylactic acid (PLA) is a thermoplastic polymer used in the packaging sector, as it has glassy transition temperature of approx. 608C, higher than the temperature of use products. It performs like traditional plastics. It is resistant to solvents and fragrances used in food field and presents as well a good barrier to vapor and permanent gases. 1 Lactic acid is a nontoxic constit- uent of the human metabolic cycle, gives absolute biocompatibil- ity to the PLA polymer. Polylactic acid/polylactide are nontoxic, biodegradable, biocompatible, bioabsorbable, compostable poly- mers obtained from renewable resources that could be thermally processed and find utilization in a variety of fields: packaging, medicine, agriculture, pharmacy, textile industry. It is approved by Food and Drug Administration (FDA). It is degraded through the mechanism of ester hydrolysis to return lactic acid, which is naturally consumed to yield carbon dioxide, water, and biomass. PLA can be also converted back to the starting material (lactic acid) which can then be purified and used to make virgin poly- mer again, avoiding down cycling and preserving the value of the lactic acid through many cycles of use. It can help reduce green- house gas emissions. Compared with other petroleum based plas- tics such as polypropylene, and polyethyleneterephthalate (PET), PLA requires the least amount of energy to produce, and releases the least amount of carbon dioxide during production. Therefore the PLA is considered a greener alternative to PET and other plastics because its supply chain requires less transportation and thus contributes less CO 2 to the atmosphere. It is used as numer- ous materials such as non-woven fibers, oriented films, extrusion coating, flexible film, cast sheet, injection molding and foam. The prohibitive cost is one factor that has kept its application still mainly confined to the high-value, specialty applications. 2 PLA use is limited in certain applications, although it is an eco- friendly bioplastic with excellent biocompatibility and process- ability. PLA presents poor toughness, being a very brittle material with less than 10% elongation at break that limits its use in the applications that need plastic deformation at higher stress levels. 3 Although the stereochemical composition of the PLA has a sig- nificant effect upon its melting point, crystallization rate, extent of crystallization, and mechanical properties, 4 the flexibility of PLA may be modified by blending it with a second polymer or a plasticizer. A lower glass transition temperature, enhanced ductility and improved processability could be achieved by changing some of the plasticizer properties: molecular weight, polarity, and end groups. 5 VC 2015 Wiley Periodicals, Inc. WWW.MATERIALSVIEWS.COM J. APPL. POLYM. SCI. 2016, DOI: 10.1002/APP.43223 43223 (1 of 11)