Effect of starch modification on the mechanical, thermal, morphological, and biodegradability properties of Nylon 6-based nanocomposites

The development of sustainable polymer materials remains a significant challenge, particularly in striking a balance between mechanical performance and environmental responsibility. In this work, starch–Nylon 6 nanocomposites were prepared using a solution casting method with different plasticizers and nanoclays. Plasticizers, such as propylene glycol, phthalates, trimellitic acid, acetyl tributyl citrate, and polyethylene glycol, were incorporated to improve flexibility. Meanwhile, bentonite and halloysite nanoclays were utilized as reinforcements to enhance strength and thermal stability. Mechanical analysis revealed that the phthalate–halloysite formulation achieved the highest tensile strength (8.0 ± 0.3 MPa), surpassing that of the pure starch control (5.0 ± 0.1 MPa). Thermal studies revealed a decomposition temperature of 265.0 ± 2.5 °C for halloysite-based composites, highlighting their superior stability relative to other formulations. Biodegradability testing under soil burial conditions confirmed significant weight loss within 30 days, largely due to starch degradation, while the Nylon 6 fraction remained stable. Water uptake experiments further demonstrated the barrier role of nanoclays, reducing moisture absorption. This study establishes starch–Nylon 6 nanoclay systems as partially biodegradable composites that provide a balance between enhanced material performance and reduced environmental impact, positioning them as promising candidates for applications where strength, stability, and sustainability are equally important.