Developing Sustainable Polymer Films Reinforced with Rice Husk Nanocellulose Extracted Using a Modified Up DeGraff Method

This study introduces a sustainable method for fabricating polymer films reinforced with cellulose nanocrystals (CNCs) extracted from rice husk via a modified Updegraff method. Addressing the dual challenges of environmental degradation and waste valorization, this research converts rice husk, a prevalent byproduct of rice milling into high-performance CNCs that are incorporated into starch-based matrices at varying concentrations. Fourier Transform Infrared (FTIR) analysis confirmed the effective removal of non-cellulosic components, with the CNC spectrum exhibiting defined cellulose peaks: an O–H stretch at approximately 3297 cm⁻¹, a C–H stretch near 2915 cm⁻¹, and a strong C–O–C band around 1032 cm⁻¹. X-ray diffraction (XRD) further revealed a significant enhancement in crystallinity, achieving a crystallinity index (CI) of up to 95% after chemical treatments. Raman spectroscopy supported these findings by displaying characteristic cellulose bands between 422–1788 cm⁻¹, while Transmission Electron Microscopy (TEM) confirmed nanoscale CNC structures ranging from 10 to 50 nm. Mechanical tests showed that the neat starch film had the highest tensile strength, approximately 11–12 MPa. Films with moderate CNC loading (0.4 mL) achieved a balanced performance, with a tensile strength of about 7 MPa. Excessive CNC addition (0.6 mL) led to agglomeration, as observed in Scanning Electron Microscopy–Energy Dispersive Spectroscopy (SEM-EDS). This resulted in a reduction of tensile strength to approximately 4 MPa. In addition, increased CNC content improved barrier properties by reducing water absorption. The eco-friendly modified Updegraff extraction of ultra-high-crystallinity (≈95 %) CNCs from rice husk, their direct incorporation into starch films, and the identification of a 0.4 mL per 50 g starch “sweet spot” for maximizing both tensile strength and moisture resistance before agglomeration are the key novelties of this study. These results underscore the potential of rice husk-derived CNCs to enhance both the mechanical and barrier properties of bioplastic films. This advancement paves the way for industrially viable, eco-friendly packaging solutions. It also contributes to sustainable waste management practices.