Synergetic Effects of Cellulose and Lignin on the Properties of Biocomposites Based on Polycaprolactone and Thermoplastic Alginate

ABSTRACT This study focuses on the development and characterization of a biocomposite composed of polycaprolactone (PCL) as a matrix with alginate thermoplastic, microcrystalline cellulose (0.0%–3.0%), and lignin (0.0%–3.0%), targeting applications that require biodegradability, biocompatibility, and mechanical strength. Processing was carried out at 70°C for blending and 90°C for molding to ensure uniform filler dispersion. Fourier‐transform infrared spectroscopy (FTIR) did not reveal significant spectral differences, suggesting limited or subtle chemical interactions among the components. Mechanical testing, performed with n = 3 specimens per formulation, showed that the incorporation of lignin increased the elastic modulus, decreased the elongation at break, and showed no significant effect on the tensile strength of the composites compared to unmodified PCL. Thermal analysis using differential thermogravimetric (DTG) profiling revealed that all samples followed similar degradation patterns, though variations in peak positions and intensities indicated differences in thermal stability and composition, particularly in modified samples (A1, A2, A3, A1L1, A2L1, and A3L1) compared to the unmodified control (A0). Field Emission‐Scanning Electron Microscopy (FE‐SEM) analysis showed that sample A3L1 had the most favorable morphology, with well‐aligned fibers embedded in a smooth, compact matrix and strong interfacial bonding, suggesting enhanced structural integrity. SEM–EDX analysis of sample A1L1 revealed the presence of carbon (51.5%), oxygen (18.9%), calcium (16.4%), chlorine (12.4%), and sodium (0.9%), confirming the heterogeneous composition of composites. These enhancements surpass the performance metrics of conventional PCL‐based composites, highlighting the value of lignin and microcrystalline cellulose as sustainable reinforcing agents.