Effect of Sugarcane Bagasse-Derived Cellulose Nanocrystals on the Thermal, Structural, Morphological and Biodegradation Properties of Poly(ε-caprolactone) and Poly(lactic Acid)

Biodegradable materials offer promising alternatives to petroleum-based polymers. This study investigates poly(ε-caprolactone) (PCL) and poly(lactic acid) (PLA) nanocomposites reinforced with 1, 3 and 5 wt.% cellulose nanocrystals (CNCs) extracted from sugarcane bagasse via melt blending. The thermal, structural, morphological and biodegradation properties were evaluated using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray scattering (WAXS/SAXS), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and biodegradation tests. SEM results revealed uniform dispersion of CNCs at low concentrations, whereas agglomeration occurred at higher concentrations for both PCL and PLA. At 1 wt.% CNCs, there was minimal impact on the biodegradation rates of both polymers, despite achieving uniform dispersion. However, significant acceleration in biodegradation was observed at 5 wt.% CNCs, attributed to the enhanced hydrophilic nature of the nanocomposites. CNCs acted as nucleating agents in PCL crystallization, while reducing the crystallization rate of PLA. This led to a mass loss of 36.4% for PCL and 82.2% for PLA, correlating with increased and decreased crystallinities, respectively. The study concludes that the hydrophilic–hydrophobic balance has a more significant influence on biodegradation rates than crystallinity or CNC dispersion.