This study investigates the effect of 3-aminopropyltriethoxysilane (APTES) concentration on the surface modification of rice husk (RH) for developing polybutylene adipate-co-terephthalate (PBAT) composites with varying filler loadings (30-50 wt%). Silane-treated RH was incorporated into PBAT via melt blending to enhance mechanical and thermal properties. The novelty lies in systematically correlating APTES concentration with RH loading, offering insights into their synergistic impact on composite microstructure and overall performance. Our approach provides a comprehensive understanding of how controlled silane treatment improved interfacial adhesion, mechanical strength, thermal stability, and maintained biodegradability. Characterization was performed using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), tensile testing, thermogravimetric analysis (TGA), water absorption, and soil burial tests. SEM revealed a more homogeneous morphology with fewer voids. The 70PBAT/30Silane RH-2% composite achieved the best mechanical performance, outperforming 4% and 6% silane-treated composites, with tensile strength improvements of 7% and 10%, and Young's modulus increases of 12% and 4%, respectively. Tensile properties indicated that for a filler loading of 30 wt%, a 2% silane concentration is sufficient, while a maximum of 6% is required for 40 wt%, and a minimum of 4% is necessary for 50 wt% filler loading. TGA showed enhanced thermal stability with higher filler content, while soil burial tests confirmed 90% mass loss after 6 months, indicating excellent biodegradability. These results highlight the potential of silane-treated PBAT/RH composites for sustainable molded products such as trays.

This study presents a novel approach to address the current issue of plastic waste in the biosphere, which poses ecological hazards and threatens living beings. Herein, a set of biodegradable composites has been developed through the melt blending of polybutylene adipate-co-terephthalate (PBAT) and rice husk (RH), aiming to discover effective surface modification techniques for enhancing mechanical properties while maintaining biodegradability above 90%. This research studied the diverse surface treatment methodologies applied to raw RH, including alkaline, acetylation, and silane treatments. The novelty of this study lies in its focus on evaluating how these treatments distinctly influence the mechanical properties and biodegradability of RH. Additionally, it seeks to understand the underlying mechanisms driving these performance changes. To further improve the compatibility between hydrophobic PBAT and hydrophilic RH, a compatibilizer such as maleic anhydride (MAH) was added. A range of analytical techniques, including scanning electron microscopy (SEM), tensile testing, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), contact angle measurement, and soil burial test, was employed to investigate the biodegradability of the composites. The results indicate that the PBAT/Silane RH/MAH composite exhibited exceptional mechanical properties, with a tensile strength of 22.49 MPa, a strain at break of 41.83%, and Young's modulus of 187.60 MPa. Furthermore, the composites developed exhibited 90% mass loss during a six-month soil burial test, confirming their remarkable biodegradability. The findings present an innovative and practical solution for utilizing RH waste in a wide range of applications, particularly in the production of molded products such as straws.