Rheological and <scp>UV</scp>‐Protecting Properties of Biobased and Biodegradable Blends for Injection Molding Applications

ABSTRACT This study investigated the effect of graphene (GRA) reinforcement on the rheological properties of a biodegradable blend based on starch‐based material (B20), polybutylene succinate (PBS), and fortified pentaerythritol ester of rosin (RES) as a compatibilizer. Prototypes produced through injection molding of B20/RES/PBS and B20/RES/PBS/GRA blends were evaluated for their susceptibility to color changes induced by UV radiation. A double capillary rheometer was employed to assess the rheological properties across shear rates ranging from 10 to 6000 s −1 . The viscosity master curves were well‐fitted to the Cross‐William‐Landel‐Ferry (WLF) model and the formulations exhibited non‐Newtonian (shear‐thinning) behavior. The blends demonstrated a pronounced dependence of viscosity on temperature, indicating a decrease as temperatures increased. The incorporation of GRA reinforcement into the blend led to a notable reduction in viscosity, contributing to an enhanced flow behavior. The activation energy ( E a ) was determined using the Arrhenius model and the composite B20/RES/PBS/GRA exhibited a higher E a value compared to B20/RES/PBS, indicating that the reinforcement with GRA requires increased energy to overcome interactions between chain segments. The incorporation of GRA significantly enhances the B20/RES/PBS blend's UV resistance due to its effective UV absorption and superior photostability, making it a promising candidate for automotive passenger compartment applications.