ABSTRACT Fully bio‐based and compostable composites are key to reducing the dependence on petroleum‐based plastics in packaging and lightweight structural applications. Poly(lactic acid) (PLA) reinforced with natural fibers offers great potential but typically suffers from hydrophilicity and weak interfacial adhesion. Here, flax textiles coated with a thin graphene layer were incorporated into PLA (up to 30 wt%) using twin‐screw extrusion followed by injection molding. The graphene coating converted the flax surface from hydrophilic to hydrophobic and improved thermal stability without damaging the fiber structure. The untreated textile reinforcement enhanced tensile and flexural moduli, while graphene‐functionalized textiles (GT) significantly accelerated PLA crystallization and reduced melt viscosity, indicating improved processability. Additionally, GT (at 20 wt%) reduced water uptake by ~43% relative to the 20 wt% UT composite after 48 h of immersion. A key feature of the composite is its remarkable photothermal performance. Under sunlight exposure, the PLA–GT composite reached ~70°C within 5 min, compared to only 37°C for neat PLA, demonstrating efficient solar energy conversion. This property is highly promising for solar‐driven disinfection, water purification, active packaging, and passive heating applications. Composting tests confirmed complete fragmentation within 14 weeks, with only a slight delay for GT samples. This scalable approach provides multifunctional, fully bio‐based PLA–flax composites that combine improved processing, enhanced durability, and excellent photothermal performance, thereby paving the way for eco‐designed functional materials for energy and environmental applications.
Aouay et al. (2026) studied this question.