Biobased Ketal–Diester Additives Derived fromLevulinic Acid: Synthesis and Effect on the Thermal Stability andThermo-Mechanical Properties of Poly(vinyl chloride)

A new class of biobased plasticizers is herein proposed as a replacement of the currently used additives. The molecules were synthesized by a selective protecting-group-free route, which was developed in order to produce valuable asymmetrical ketal–diester derivatives from the renewable levulinic acid, overcoming the typical drawbacks of these types of reactions. Five molecules with different side chains were successfully obtained and fully characterized by means of NMR and FT-IR spectroscopies. These ketal–diester additives were then tested in poly(vinyl chloride) (PVC) as the model polymer. Their compatibility and plasticizing effect were evaluated by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), dynamic-mechanical thermal analysis (DMTA), and thermogravimetric analysis (TGA). The emerged trend showed a clear correlation between the structural features of the ketal–ester and the thermal and mechanical properties of the material. In particular, the best results in terms of ...