Surface Modification of Rise Husk As Filler In Low Density Polyethylene Composites Using Salt Assisted Sonication Method

Surface modification of natural fibers is essential to improve interfacial bonding in polymer composites. This study investigates the synergistic effect of sodium salts (NaCl and Na2CO3) and ultrasonic treatment on rice husk as a sustainable filler for low-density polyethylene (LDPE) composites. Rice husk powders were treated with 5–10 wt% aqueous salt solutions under ultrasonic irradiation (40 kHz, 60 min) to promote delignification and surface activation. The modified fibers were characterized by FTIR, TGA, and gravimetric lignin analysis. Results showed that Na2CO3-assisted sonication reduced lignin content from 19.6 % to 9.7 %, eliminated lignin-associated FTIR peaks, and increased hydroxyl group absorption intensity. Thermal stability also improved, with Tonset and Tmax values rising to 262 °C and 346 °C, respectively. These outcomes confirm that alkaline salt–ultrasonic synergy effectively enhances the chemical purity and heat resistance of rice husk, providing an eco-efficient route for converting agricultural waste into high-performance polymer composite fillers.