Role of silane compatibilization on cellulose nanofiber reinforced poly (lactic acid) (PLA) composites with superior mechanical properties, thermal stability, and tunable degradation rates.

Poly (lactic acid) (PLA) is a widely produced bio-based polymer known for its biodegradability and renewability, but its brittleness, low heat resistance, and weak mechanical properties limit its broader use. To address these challenges, TEMPO-oxidized cellulose nanofibers (TOCNF) were extracted from dissolving pulp using TEMPO-oxidation and high-pressure homogenization. These TOCNF were modified with silane to reduce hydrophilicity and improve compatibility with PLA. The resulting silane modified TOCNF (S-TOCNF) were incorporated into PLA via solution casting to form S-TOCNF/PLA composite. Characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA) showed that S-TOCNF improved crystallization, compatibility, and enhanced the composite's mechanical properties. At 3 % S-TOCNF content, the S-TOCNF/PLA composites developed in this study achieve a balanced enhancement in mechanical properties, the tensile strength increased by 35.78 %, elongation at break by 66.25 %, and modulus by 25.99 % compared to pure PLA. Thermal stability improved, with decomposition temperature rising to 340 °C, while maintaining over 50 % light transmittance. Additionally, the degradation rate could be controlled by varying S-TOCNF content. This study demonstrates the potential of S-TOCNF to significantly enhance the mechanical, thermal, and degradation properties of PLA-based composites.