Stabilization effect of kraft lignin into PBAT: Thermal analyses approach

Abstract

Sterically hindered phenols are an important class of synthetic antioxidants for polymers, commonly incorpo-rated to inhibit polyolefins or polyesters oxidation. However, synthetic antioxidants use is under restricted regulation due to their potential health risk and environmental impacts. Thus, great interest has been attracted to the phenol-based natural antioxidant such as lignin. This work aimed to evaluate the thermostability of kraft lignin (KL) as a natural antioxidant when incorporated into poly(butylene adipate-co-terephthalate) (PBAT) matrix. PBAT-KL films (0%, 1%, 3%, 5% and 10%, by mass) were prepared by twin-screw extru-sion followed by thermo-compression. These materials were examined in detail for their effect on the thermal stability using the oxidative induction time (OIT), oxidative induction temperature (OITemp) and thermograv-imetric analysis (TG). According to the results, lignin-containing compositions have improved thermal re-sistance in oxidative environment, compared to neat PBAT. However, 10 wt.% lignin composition presented the lowest thermostability among lignin-containing compositions. The results showed that kraft lignin pro-motes the thermal stabilization of PBAT films at the optimal concentration of 1% by mass.