This study investigates the valorization of mussel shell waste as a bio-derived filler in poly(L-lactic acid) (PLLA) to promote sustainable materials aligned with circular economy principles. Mussel shells, a seafood industry byproduct rich in biogenic calcium carbonate, were ground into powder and incorporated into PLLA at 10–50 wt%. The resulting composites were thoroughly characterized using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM-EDX), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA), and uniaxial tensile testing to assess morphological, chemical, thermal, and mechanical properties. Incorporation of mussel shell powder significantly increased stiffness, with the storage modulus improving by more than 70% at the highest filler content. DSC results suggest that mussel shell powder promotes a heterogeneous nucleation effect in PLLA, enhancing crystallization and modifying crystallization behavior. DMTA measurements further demonstrated a substantial increase in thermomechanical stiffness while only slightly affecting the glass transition temperature, indicating restricted chain mobility due to the presence of the rigid mineral filler. TGA revealed a second degradation step from calcium carbonate decomposition, without compromising processability. Conversely, tensile strength, ductility, and toughness decreased progressively, reflecting the typical stiffness-toughness trade-off of mineral-filled composites. Overall, this work highlights the potential of mussel shell powder not only as a sustainable bio-derived filler but also as a functional reinforcing phase that can influence crystallization behavior and thermomechanical performance of PLLA.
Jourdainne et al. (Thu,) studied this question.