Impact of alkali treatment with varying soaking times on the physico-chemical, tensile, and morphological properties of Smilax zeylanica plant fibers

This work uses a variety of analytical methods to examine how Smilax zeylanica fibers are affected by an alkali treatment. Treatment with 5% NaOH for 60 min resulted in significant enhancements across several properties. Thermogravimetric analysis (TGA) and differential thermogravimetry (DTG) showed that the treated fibers had the highest thermal degradation temperature of 349.13 degrees C and a maximum weight loss of 65.8%, with an 82.5 kJ/mol kinetic activation energy (Ea) being the most outstanding. Single fiber tensile testing revealed a 48% increase in tensile strength to 196.50 +/- 47.05 MPa and a 91% improvement in Young's modulus to 19.63 GPa, although strain at break decreased by 5%. The glass transition temperature (Tg) increased from 349.23 to 379.15 degrees C, according to differential scanning calorimetry (DSC), indicating greater thermal stability. FTIR, or Fourier transform infrared spectroscopy, verified that hemicellulose and lignin could be effectively removed, improving the purity of cellulose. X-ray diffraction (XRD) showed an increase in crystallinity index from 43.74 to 54.21% and crystallite size from 16.47 to 19.52 nm. Nuclear magnetic resonance (NMR) analysis supported the removal of non-cellulosic components and improved cellulose quality. Atomic force microscopy (AFM) measurements revealed a 52.25% reduction in surface roughness, indicating a smoother and more stable fiber surface. Alkali treatment at 5% NaOH for 60 min significantly improves the thermal, mechanical, and surface properties of Smilax zeylanica fibers.