Post-extrusion heat-treatment as a facile method to enhance the mechanical properties of extruded xylan-based polymeric materials

Hemicelluloses are among the most abundant renewable polymers in nature, and their processing into biodegradable polymeric materials via extrusion was recently reported as a novel alternative technique for solvent casting. A simple heat-treatment step conducted after the extrusion of corn cob xylans was found to enhance the mechanical properties of strips by altering their moisture absorption behavior. Depending on the heat-treatment temperature, which varied between 60 degrees C and 150 degrees C, xylan- based strips with an ultimate tensile strength greater than 120 MPa, elongation at break of around 30% and elastic modulus of approximately 1.2 GPa were obtained. The equilibrium moisture content of the strips decreased with increasing heat-treatment temperature. Considering that water acts as a plasticizer for hemicellulose based materials, the changes in the mechanical properties were found to be associated with the changes in the equilibrium moisture contents of the strips.