Development and Characterization of New Environmentally Friendly Polylactide Formulations with Terpenoid-Based Plasticizers with Improved Ductility

This work addresses the potential of two biobased terpenoids, linalyl acetate and geranyl acetate, as environmentally friendly monomeric plasticizers for polylactide (PLA). Plasticized formulations of PLA containing 10 wt.% and 20 wt.% terpenoids were melt-compounded in a twin-screw co-rotating extruder and, subsequently, processed by injection moulding for further characterization. In addition, a reactive extrusion process (REX) was carried out on plasticized formulations containing 20 wt.% terpenoids with dicumyl peroxide to anchor the plasticizer molecules into the PLA backbone. Both terpenoids led to a remarkable plasticization effect on PLA, with a noticeable increase in ductile properties. In particular, the elongation at break of PLA, around 4.7%, was improved to values above 230% for all the plasticized formulations, even for low terpenoid concentration of 10 wt.%. Terpenoids also provide increased crystallinity because polymers chains have more mobility and are more readily arranged. This was observed by shifting the cold crystallization process to lower temperatures. As with other monomeric plasticizers, a clear decrease in the glass transition temperature from 61.5 & DEG;C (neat PLA), to values of around 40 & DEG;C for the plasticized formulations with 20 wt.% terpenoid was obtained. The obtained formulations show high potential since the plasticization efficiency of these terpenoids is very high, thus leading to new toughened-PLA formulations with improved ductility.