Biochar from digestate pyrolysis as a filler for biopolymer blends: effect of blend composition

This study investigates biochar (BC) composites based on biopolymer blends, focusing on the effect of the biopolymer weight ratio on the final BC composites. The blends studied in this work were obtained by varying the weight ratio of poly-butylene adipate-co-terephthalate (PBAT) and polylactic acid (PLA) due to their great importance in packaging and agricultural fields. In particular, BC has been produced in our laboratories by the slow pyrolysis of the digestate obtained from the anaerobic digestion of the organic fraction of municipal solid waste (OFMSW). The effect of BC on PBAT and PLA biopolymer matrices is different, and for the blend compositions the relative weight ratio between PBAT and PLA plays an important role. In order to better investigate the filler/polymer interactions, biochar particles were dimensionally, morphologically and chemically characterised. The biocomposite blend has been fully characterised: Rheological, morphological, mechanical and dynamic-mechanical characterisations have been carried out, highlighting that a strong chemical interaction occurs between PLA and BC particles.