Rheological and UV ‐Protecting Properties of Biobased and Biodegradable Blends for Injection Molding Applications
Loleny Tavares, Liliana R. Sousa, Sara Magalhães da Silva, Paulo S. Lima, J. M. Oliveira 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 (Ea) was determined using the Arrhenius model and the composite B20/RES/PBS/GRA exhibited a higher Ea 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.