Aliphatic Polyester-Based Green Renewable Eco-composites from Agricultural Residues: Characterization and Assessment of Mechanical Properties

The biodegradability, morphology, and mechanical properties of composite materials consisting of maleic anhydride-grafted poly(butylene succinate adipate) (PBSA-g-MA) and agricultural residues (wheat bran, WB) were evaluated. Composites containing maleic anhydride-grafted PBSA (PBSA-g-MA/WB) exhibited noticeably superior mechanical properties compared with those of PBSA/WB because of greater compatibility with WB. PBSA/WB exhibited a tensile strength at break of approximately 2-15 MPa more than PBSA-g-MA/WB. The dispersion of WB in the PBSA-g-MA matrix was highly homogeneous as a result of ester formation and the subsequent creation of branched and cross-linked macromolecules between the anhydride carboxyl groups of PBSA-g-MA and hydroxyl groups in WB. Additionally, the PBSA-g-MA/WB composites were more easily processed due to their lower melt viscosity. Water resistance of PBSA-g-MA/WB was higher than that of PBSA/WB, although weight loss of composites buried in Azospirillum brasilense BCRC 12270 liquid culture medium compost indicated that both were biodegradable, especially at high levels of WB substitution. After 60 days, the weight loss of the PBSA-g-MA/WB (40 wt%) composite was greater than 90 %. PBSA/WB exhibited a weight loss of approximately 4-8 wt% more than PBSA-g-MA/WB. The PBSA/WB and PBSA-g-MA/WB composites were more biodegradable than pure PBSA, which implies a strong connection between WB content and biodegradability.