PBAT green composites: Effects of kraft lignin particles on the morphological, thermal, crystalline, macro and micromechanical properties

Kraft lignin particles (KLPs) were introduced into a commercial biodegradable poly(butylene adipate-co-terephthalate) (PBAT) matrix to produce composite material in a mini-extruder. The effect of KLPs content on the morphology, thermal, crystalline, and micro and macro mechanical properties of the PBAT/KLPs was investigated. Results showed that the tensile properties of PBAT improved with the addition of lignin. Dynamic Mechanical Analysis (DMA) showed that the storage modulus of composites increased with increasing of KLPs and Tg slightly shifted to a lower temperature. Differential scanning calorimetry (DSC) revealed that lignin strongly nucleates the crystallization of PBAT. Thermogravimetric analysis (TGA) showed that composites started to degrade at a lower temperature compared with neat PBAT while displaying higher ash residue. Small-angle X-ray scattering (SAXS) analysis showed that under a uniaxial stretch of the PBAT/KLP films nano and microcavities formed due to the debonding of PBAT from KLPs in their polar regions.