Stabilization effect of kraft lignin into PBAT:Thermal analyses approach

Sterically hindered phenols are an important class of synthetic antioxidants for polymers, commonly incorporatedto inhibit polyolefins or polyesters oxidation. However, synthetic antioxidants use is under restrictedregulation due to their potential health risk and environmental impacts. Thus, great interest has been attractedto the phenol-based natural antioxidant such as lignin. This work aimed to evaluate the thermostability ofkraft 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 extrusionfollowed by thermo-compression. These materials were examined in detail for their effect on the thermalstability using the oxidative induction time (OIT), oxidative induction temperature (OITemp) and thermogravimetricanalysis (TG). According to the results, lignin-containing compositions have improved thermal resistancein oxidative environment, compared to neat PBAT. However, 10 wt.% lignin composition presentedthe lowest thermostability among lignin-containing compositions. The results showed that kraft lignin promotesthe thermal stabilization of PBAT films at the optimal concentration of 1% by mass.Keywords: Poly(butylene adipate-co-terephthalate), Kraft lignin, Biodegradable polymer, Thermal analysis,Oxidative degradation.