Green Functionalization of CaCO ₃ via Biobased Modifiers: A Sustainable Strategy to Enhance Interfacial and Mechanical Behaviors in Bamboo‐Plastic Composites

ABSTRACT Bamboo‐plastic composites (BPCs) are recognized as a sustainable material that aligns with the “double carbon” strategy, demonstrating considerable potential for application in both packaging and construction industries. However, the inadequate interfacial compatibility between bamboo fibers (BFs) and the polymer matrix substantially undermines the mechanical properties of BPCs. Although the incorporation of cost‐effective and widely available inorganic CaCO ₃ can improve certain properties, its high surface polarity results in poor dispersion within the BFs‐polymer composite system, thus limiting its efficacy as a reinforcing agent. To address these challenges, this study introduced environmentally friendly modifiers through the synergistic combination of KH‐570/DL‐malic acid (DL) and sodium citrate (SC)/DL for the surface functionalization of CaCO ₃ . This innovative strategy effectively transformed CaCO ₃ from a conventional “inorganic filler” into an active “interfacial compatibilizer” which was processed via melt‐blending with BFs and the polypropylene (PP) matrix to optimize interfacial compatibility. The results demonstrated that at a modifier dosage equivalent to 5% of the mass of CaCO ₃ , with optimal KH:DL and SC:DL ratios of 5:5 and 4:6, the KH/DL‐C10F40 and SC/DL‐C10F40 groups demonstrated enhanced mechanical properties and processability compared to C10F40. Specifically, there were observed improvements in tensile strength by 20.67% and 20.01%, flexural strength by 6.94% and 4.43%, impact strength by 19.60% and 27.42%, and melt flow index by 143.79% and 124.85%, respectively. Furthermore, the composites exhibited significant improvements in dimensional stability, photostability, and thermal stability. This study established a novel strategy utilizing modified CaCO ₃ to produce BPCs with excellent mechanical properties and processability, which possessed substantial scientific and practical significance.