Nano‐Magnesium Oxide Particles Modified Bamboo Flour/Polylactic Acid Composites: Mechanical Properties, Thermal Performance and Degradation Behaviors

ABSTRACT This study fabricated nano‐magnesium oxide (nano‐MgO) modified bamboo flour/polylactic acid (BF/PLA) composites via melt extrusion and injection molding, with nano‐MgO loadings of 0, 1, 3, and 5 wt.%. The microstructure, mechanical, hygroscopic, thermal, and aging resistance properties were systematically investigated using triplicate measurements ( n = 3 per group). Results showed that appropriately dosed nano‐MgO dispersed uniformly in the matrix, reduced hydroxyl groups on bamboo flour, and enhanced interfacial compatibility and bonding without altering the basic chemical structure of the composites. The composite with 1 wt.% nano‐MgO exhibited optimal mechanical performance, with 57.2% higher tensile strength (17.77 ± 0.45 vs. 11.31 ± 0.32 MPa) and 34.2% higher flexural strength (41.35 ± 1.12 vs. 30.81 ± 0.87 MPa) than the control. Impact strength reached the maximum at 3 wt.% loading (4.15 ± 0.18 kJ/m 2 , +39.9%), demonstrating a balance between strength and toughness. Increasing nano‐MgO content slightly enhanced hygroscopicity but reduced water absorption, with thickness swelling reaching a minimum at 3 wt.%. Thermal analysis demonstrated that nano‐MgO acted as a nucleating agent, increasing PLA crystallinity from 5.21% to 20.33%. It also promoted carbonization and formed a physical barrier during pyrolysis, increasing char residue from 14% to 20%. Aging tests indicated that 1 wt.% nano‐MgO endowed the composite with the best aging resistance under soil burial and refrigerated conditions. Overall, 1 wt.% nano‐MgO is the optimal loading for simultaneous improvement of comprehensive properties, providing a viable strategy for high‐performance biodegradable composites.