All natural cork composites with suberin-based polyester and lignocellulosic residue

Suberin is an aromatic-aliphatic cross-linked polyester structure which constitutes cell wall structures of cork. It is particularly interesting for its use of monomeric compounds towards renewable bio-based polymers. In this study, the extraction of suberin monomers was successfully done by green method using alkaline hydrolysis combined with mechanical grinding. As the mechanical grinding was applied along with hydrolysis process, the maximum yield of depolymerized suberin monomer (DSM) with relatively low energy and less time was acheived. The polarity and functionality of DSM extracted in this study also showed higher values compared to conventional reflux hydrolysis process. Polyesterification and curing behavior of DSM were examined with molecular weights and mechanical properties of the ensuing polyesters. Tensile properties of suberin-based polyesters are reported for the first time that the maximum strength was found to be 7.3 MPa while Young's modulus was found to be 105 MPa. Furthermore, all natural cork composites were fabricated which comprise suberin-based polyester as matrix and lignocellulosic residue as reinforcement, and also reported their significantly enhanced tensile properties showing the great potential as an alternative green polymer composites for various engineering applications.