Structural, mechanical, and thermal characterization of PBAT/wheat flour by-product biodegradable sheets processed by extrusion-calendering

This study aimed to develop biodegradable sheets using a wheat flour by-product (glue flour, GF) and poly(butylene adipate-co-terephthalate) (PBAT) through extrusion-calendering. Sheets were characterized for physical, mechanical, barrier, thermal, optical, and morphological properties. The resulting material presented low water solubility (7.36%), moderate barrier performance (WVP of 4.5 × 10⁻¹¹ g m⁻¹ s⁻¹ Pa⁻¹), and low mechanical strength (TS of 1.80 MPa, ELO of 16.94%), likely due to weak interactions and phase immiscibility between GF and PBAT. Thermal analysis showed transitions corresponding to starch and PBAT domains, and FTIR and SEM revealed incomplete integration. Despite limited mechanical properties, the sheets exhibited good processability and moderate barrier function, indicating their potential for biodegradable packaging with further formulation optimization.