Tailoring Polyvinyl Alcohol/Carnauba Wax Film Properties Through Plasticizer Selection: A Pathway to Optimized Biodegradable Materials

Polyvinyl alcohol (PVA)-based films are promising biodegradable alternatives to petroleum-derived plastics; however, their high rigidity and moisture sensitivity limit practical applications. In this study, PVA/carnauba wax (CW) films were prepared via solution casting and systematically modified using four plasticizers: glycerol (GLY), sorbitol (SOR), glucose (GLU), and sucrose (SUC), at concentrations of 0.1–0.5% (v/w, relative to PVA). Thermal analysis showed that GLY and SOR effectively reduced the glass transition temperature from 52.35 °C (control) to as low as 49.14 °C (0.2% GLY) and 50.70 °C (0.4% SOR), while SUC and SOR plasticized films exhibited improved thermal stability, with the highest melting temperature observed for 0.3% SUC (80.6 °C). SEM micrographs revealed that GLY at moderate concentrations (0.2–0.3%) produced the most homogeneous film morphology, whereas SUC at higher concentrations led to surface roughness and phase separation. Water contact angle measurements showed increased surface hydrophobicity at low plasticizer contents, with 0.1% GLY and 0.2% GLU exhibiting contact angles above 100° compared to the control film (