MODIFIED PLANT-FIBER-REINFORCED FULLY BIODEGRADABLE WOOD-PLASTIC COMPOSITES FOR SUSTAINABLE LANDSCAPE ARCHITECTURE: INTERFACE COMPATIBILITY AND AGING MECHANISM

Abstract

The growing demand for sustainable materials in landscape architecture has highlighted the potential of polylactic acid/polybutylene adipate-terephthalate (PLA/PBAT)-based wood-plastic composites. However, poor interfacial compatibility between the hydrophilic plant fibers and the hydrophobic polyester matrices, coupled with susceptibility to hydrolytic degradation, limits their outdoor applications. This study presents a synergistic modification strategy for bamboo powder using a silane coupling agent (KH550) and nano-silica (Nano-SiO2), integrating all-atom molecular dynamics (MD) simulations with accelerated aging experiments to elucidate the enhancement mechanism of "chemical bridging–physical filling. " MD simulations revealed that the modification forms a dense "core-shell" barrier via covalent anchoring and a robust hydrogen-bond network, reducing the interfacial free volume to 14.1 % and lowering the water molecule self-diffusion coefficient from 4.58 × 10–7 to 0.42 × 10–7 cm2 s–1. This microscopic moisture barrier underpins the macroscopic aging resistance. Accelerated UV-condensation aging tests (1000 h) confirmed that the modified composites preserved the polyester backbone, with a weight-average molecular weight retention of 88.4 %, a tensile strength of 84.3 %, and an impact strength of 81.2 %. The surface color change was limited to E = 4.2, markedly outperforming unmodified composites. Additionally, the initial properties were improved: water absorption decreased from 4.25 % to 1.85 %, tensile strength reached 46.5 MPa, and impact strength reached 6.2 kJ m–2, achieving concurrent rigidity and toughness enhancement. These results demonstrate that nano-synergistic modification effectively mitigates weathering-induced degradation in PLA/PBAT composites, offering a practical pathway for their sustainable application in outdoor landscape environments.