Stabilization effect of kraft lignin into PBAT:Thermal analyses approach

Abstract

Sterically hindered phenols are an important class of synthetic antioxidants for polymers, commonly incorporated
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 extrusion
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 thermogravimetric
analysis (TG). According to the results, lignin-containing compositions have improved thermal resistance
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 promotes
the 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.