The use of marine biomass in polymer matrices as viable approach to designing new sustainable materials is becoming increasingly common. The development of sustainable polymer composites reinforced with renewable resources has attracted increasing attention. In this study, poly(lactic acid) (PLA)-based biocomposites reinforced with brown seaweed powder (Fucus serratus) at different weight fractions (10, 20, and 30 wt%) were developed. To enhance interfacial interactions between the polylactic acid (PLA) matrix and the seaweed filler, maleated PLA (PLAMA) was synthesized via reactive extrusion and used as a compatibilizing agent. FTIR spectra revealed characteristic absorption bands, confirming the successful grafting of maleic anhydride onto PLA. The addition of seaweed powder resulted in reduced tensile strength and strain at break, increased water absorption, and enhanced crystallinity due to a strong nucleating effect. However, the addition of PLAMA significantly improved interfacial adhesion, leading to enhanced mechanical performance, reduced water uptake, and a more homogeneous morphology. Incorporation of 30 wt% seaweed led to a 26% increase in the Young’s modulus of the composite compared to neat PLA. Thermal properties were not significantly affected by filler addition or compatibilization. These results demonstrate the potential of marine biomass as an effective reinforcement for PLA-based biocomposites intended for sustainable material applications.
