New tartrate and α-tocopherol based environmentally friendly plasticizers for improvement of the ductility of polylactic acid

Abstract

This study focuses on developing environmentally friendly plasticized poly(lactide) (PLA) formulations using tartaric acid and α-tocopherol at 20 wt%. The extrusion and injection molding processes demonstrated the industrial applicability of these plasticizers. Mechanical tests revealed positive results for tartrate-based plasticizers, with elongation at break surpassing 220 %, while α-tocopherol succinate achieved 170 %. However, α-tocopherol acetate showed limited PLA plasticization. Field emission scanning electron microscopy confirmed plasticization in fractured surfaces. Thermal analysis indicated a reduction in PLA's glass transition temperature (Tg) from 60 °C to around 30 °C with these plasticizers, underscoring tartrates' exceptional efficiency. The cold crystallization temperature (Tcc) decreased for all plasticized samples due to enhanced chain mobility. Thermomechanical analysis revealed dimensional shrinkage, with dimethyl tartrate (DMT) causing less pronounced effects. Generally, tartrates yielded formulations with superior properties, attributed to their lower molecular weight compared to α-tocopherol-derived plasticizers. Notably, all plasticizers employed are an eco-friendly approach to improve PLA's processability and enhancing ductile properties.