Masterbatch‐Assisted Fabrication of Polylactic Acid/Reduced Graphene Oxide Nanocomposites Exhibiting Mechanical Enhancement and UV ‐C Aging Resistance

ABSTRACT Polylactic acid (PLA) is a promising bio‐based polymer; nonetheless, its extensive application is still limited by poor fracture toughness, low thermal stability, and strong susceptibility to degradation induced by ultraviolet (UV) radiation. In this study, nanocomposites of PLA with reduced graphene oxide (rGO) were prepared through a masterbatch dilution approach. First, a PLA/2 wt% was produced by twin‐screw extrusion, a process compatible with current industrial practices. The masterbatch was subsequently diluted with neat PLA via melt compounding and processed into films by compression molding. The structural, thermal, mechanical, and aging behaviors of the PLA/rGO nanocomposites were systematically investigated, showing improvement compared to neat polymer. The presence of rGO was found to influence the mechanical and thermo‐mechanical response, with both Young's modulus and the storage modulus increasing with filler content, reaching values up to 20%–25% higher than those of neat PLA. Notably, the nanocomposites presented strong resistance to accelerated UV‐C aging; while neat PLA underwent severe cracking, showing a reduction of glass transition temperature of ca. 14°C, and complete mechanical failure, the composites retained their initial morphology and preserved their initial mechanical performance to a great extent, maintaining up to 73% of the original Young's modulus and up to 94% of initial tensile strength. These findings highlight the potential of the masterbatch route for producing durable PLA nanocomposites through industrially compatible processing routes, thus extending the applicability of this bio‐based polymer in several fields, such as automotive and consumer products.