Combined effects of wood flour and thermoplastic starch on the physical, thermal, and weight loss properties of polylactic acid biocomposites

Abstract This study investigates the combined effects of wood flour (WF) and a starch-based compound on the physical, thermal, and soil-burial mass loss properties of polylactic acid (PLA) biocomposites, intentionally omitting compatibilizers to isolate inherent interfacial interactions. Composites were prepared via extrusion and compression molding with varying ratios of PLA (30–50 wt%), starch-based compound (20–60 wt%), and WF (10–30 wt%). Characterization included FTIR spectroscopy, density measurements, contact angle analysis, soil-burial tests, and TGA/DSC. FTIR analysis revealed carbonyl peak shifts from 1746 to 1735 cm −1 , suggesting polar interfacial interactions consistent with hydrogen bonding between PLA and the hydroxyl-containing fillers. Density measurements indicated high compaction (relative density > 0.95). Soil-burial tests demonstrated 4–7% mass loss over 6 weeks. Most notably, DSC revealed WF as a potent nucleating agent, increasing PLA crystallinity from 49.50 to 73.15%. This study provides crucial baseline data on intrinsic filler interactions and synergies for sustainable biocomposite design without mandatory compatibilization.