The increasing demand for sustainable polymer additives has raised attention on the development of biobased plasticizers as alternatives to conventional fossil-derived compounds. In this work, glycerol trihexanoate (GTH) was synthesized via a solvent-free reaction between glycerol and hexanoic acid, two renewable, biobased, and nontoxic building blocks. The plasticizing effect of GTH is investigated on a fully amorphous polymer, such as poly(vinyl chloride) (PVC), and on poly(3-hydroxybutyrate-c