Eco-friendly High-Density Polyethylene Nanocomposites Reinforced with Rice Straw-Derived Nanocellulose: Synthesis, Characterization, and Biodegradability Assessment

This study presents an innovative strategy for fabricating sustainable nanocomposites by using rice straw, a common agricultural byproduct, as a reinforcing agent for high-density polyethylene (HDPE). This research integrates waste valorisation, nanomaterial synthesis, and polymer engineering to develop materials with enhanced properties and a reduced environmental impact. The mechanical, thermal, and biodegradation characteristics of the resulting composites were thoroughly investigated. Nanocellulose, extracted from rice straw through a series of treatments (alkaline pulping, bleaching, and acid hydrolysis), resulted in particles with diameters between 15 and 24 nm. Composites with nanocellulose loadings between 0.1% and 7% demonstrated notable improvements in mechanical performance. The tensile strength increased by as much as 14.38%, and the elastic modulus showed an enhancement of up to 31.50% at an optimal nanocellulose loading range of 0.4% to 0.8%. Spectroscopic analysis confirmed enhanced thermal stability and evidence of interaction between HDPE and nanocellulose. Furthermore, preliminary biodegradation tests indicated a partial degradation of 0.28% over five months through soil burial tests, showing that nanocellulose incorporation facilitates environmental decomposition