Environmentally Friendly Alternatives to Bis(2-ethylhexyl) Phthalate as Plasticizers for Poly(lactic acid)

This study evaluated a conventional petroleum derived diester plasticizer and three environmentally friendly diester plasticizers for polylactic acid (PLA), focusing on processing, mechanical, thermal, chemical, and surface properties. Bis(2-ethylhexyl) phthalate (DEHP), a widely used plasticizer for PLA, is derived from petrochemical sources and is classified as a pollutant, which motivated the search for biobased alternatives. PLA compounds containing biobased diester plasticizers were prepared by extrusion, and test specimens were obtained by injection molding. The results showed that the biobased plasticizers bis(2-ethylhexyl) maleate (DEHM) and bis(2-ethylhexyl) sebacate (DEHS) significantly improved ductility, which was confirmed by fracture surface analysis. Thermal and thermomechanical analyses indicated enhanced chain mobility, along with increased crystallization and a reduction in glass transition temperature. Chemical characterization confirmed that plasticization occurred through physical interactions, preserving the chemical integrity of the polymer matrix. In addition, diester plasticizer incorporation modified surface wettability, facilitating water diffusion and increasing affinity toward distilled water, which could be beneficial for applications such as biodegradable packaging or agricultural materials, where moisture interaction may influence end-of-life behavior and environmental degradation.