Synergistic Effect of Silanized Ramie Fiber and Montmorillonite Clay on the Mechanical, Thermal, and Dynamic‐Mechanical Properties of Polyester Composites

ABSTRACT Multiscale polymer composites combining natural fibers and layered silicates can balance stiffness, toughness, and thermal stability when interfacial interactions are properly engineered. This study develops polyester composites with 10 vol% short ramie fibers (45 mm) and 3 wt% montmorillonite, with both reinforcements silanized using 3‐(trimethoxysilyl)propyl methacrylate. Spectroscopy and thermal analysis confirmed successful grafting on clay and fiber, and the microscopy revealed reduced clay agglomerates and improved dispersion when silanized clay was used. Dual silanization (fiber + clay) increased the 10% mass‐loss temperature relative to fiber‐only systems, indicating a barrier effect, and raised the glass‐transition temperatures while lowering adhesion factor A (~0.6) and efficiency coefficient C (~0.44–0.49), consistent with stronger interfacial bonding. Impact strength improved, and long‐term water uptake decreased to levels close to clay‐only and neat resin. Overall, simultaneous silanization of ramie fiber and montmorillonite enhances thermal stability, viscoelastic performance, impact resistance, and moisture tolerance, providing a practical route to higher‐performance, bio‐leaning multiscale polyester composites.