Effectiveness of modified lignin on poly(butylene adipate-co-terephthalate)/poly(lactic acid) mulch film performance

In this work, the biodegradable poly(butylene adipate-co-terephthalate) (PBAT)/poly(lactic acid) (PLA) blend (ECOVIO (R)) and lignin, a renewable and biodegradable natural polymer with high UV absorption and modified by gamma radiation were used to produce agriculture mulch films. Lignin was gamma-irradiated at 30 and 60 kGy. The irradiated and non-irradiated lignin content of 2 wt% was incorporated into PBAT/PLA blend matrix using a twin-screw extruder and extrusion blown film to prepare flexible films. PBAT/PLA/LIGNIN films were characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), tensile tests, contact angle, and UV-Vis analysis. FTIR spectra showed partial miscibility between PBAT/PLA and lignin, being intensified in irradiated lignin compounds. The DSC and XRD results confirmed that the degree of crystallinity of the blends was not significantly influenced by lignin addition. FE-SEM images showed better dispersion and miscibility in PBAT/PLA/Irradiated lignin. Miscibility improvement provided by irradiated lignin promoted better mechanical properties, mainly with lignin irradiated at 60 kGy. PBAT/PLA/LIGNIN films containing 2 wt% showed excellent UV-barrier property and greater hydrophobicity. Summing up, incorporation of low contents of irradiated lignin could be an interesting alternative to produce biodegradable UV-blocking agriculture mulch films.

Automated summary

In this study, modified lignin and biodegradable polymer PBAT/PLA were used to produce agriculture mulch films, and their properties were characterized and tested. The results showed that the addition of irradiated lignin improved the compatibility between PBAT/PLA and lignin, and enhanced the mechanical properties and UV-blocking performance of the films.