Impact of Structural Differences Between PCL and PBS on the Performance and Characteristics of PLA/PCL/CAB and PLA/PBS/CAB Melted‐Ternary Blends With Hemp Hurd as a Sustainable Green Filler

ABSTRACT The impact of structural differences between poly(ε‐caprolactone) (PCL) and poly(butylene succinate) (PBS) on poly(lactic acid) (PLA)‐based ternary blends incorporating cellulose acetate butyrate (CAB) was examined, highlighting the role of hemp hurd (HH) as a sustainable filler in influencing morphology, mechanical properties, and stability. The miscibility of ternary blends was predicted using the Coleman and Painter model and validated through optical ternary phase diagrams, revealing that PLA/PCL exhibited phase separation, while PLA/PBS showed better compatibility due to enhanced molecular interactions. The 85/5/10 and 75/10/15 compositions of both PLA/PCL/CAB and PLA/PBS/CAB were identified as miscible and further characterized. Fourier transform infrared spectroscopy (FTIR) revealed distinct absorption shifts, supporting stronger interactions in PLA/PBS‐based blends. X‐ray diffraction (XRD) and tensile testing demonstrated that PLA/PBS/CAB had lower crystallinity and improved mechanical properties due to greater chain mobility and stress distribution. However, HH incorporation reduced tear strength across all blends, with a more pronounced decline in PLA/PCL/CAB, likely due to its lower compatibility. The differences in tear strength suggest that PBS contributes to better elasticity and structural integrity compared to PCL. These findings underscore the significance of polymer compatibility in tuning the mechanical properties of PLA‐based blends and highlight the potential of HH as a bio‐based filler for sustainable polymer composites, offering insight into the design of eco‐friendly materials with optimized performance.