A critical study of sustainable biocomposites developed from rheologically distinct poly(butylene adipate‐co‐terephthalate) ( <scp>PBAT</scp> ) reinforced with biocarbon from coconut ( <i>Cocos nucifera</i> ) for rigid applications

Abstract This study investigates the impact of rheological behaviour on the development of highly filled biocomposites for rigid applications using two grades of poly(butylene adipate‐co‐terephthalate) (PBAT). PBAT, a fully biodegradable polymer, has garnered significant attention as an alternative to non‐biodegradable plastics in flexible packaging applications. However, increasing filler content in PBAT can enhance its stiffness, thereby expanding its potential for rigid applications. Filler incorporation is critically influenced by the polymer's flow behaviour, and excessive filler loading in a highly viscous matrix can lead to a decline in material's ease of processing and performance. This research is focused on the processing‐performance evaluation of low melt flow (MFI) and high MFI PBAT filled biocarbon composites. While PBAT 1 supports up to 30 wt.% biocarbon, PBAT 2 can incorporate 50 wt.% biocarbon. Overall, at maximum filler loading, the mechanical and thermal performance of PBAT 2 ‐based composites were superior as compared to those of PBAT 1 composites. The tensile and flexural moduli of PBAT 2 composites increased by 122% and 171%, respectively. Additionally, the thermal stability showed a 38% improvement as compared to PBAT 1 composites. This study underscores the effect of the rheological properties on composites development and provides valuable insights for selecting optimal polymer matrices for high‐filler, rigid applications.