Sisal fiber, a natural and renewable resource, is extensively used in composite applications due to its excellent mechanical properties and sustainability. However, its high-water absorption and limited thermal stability hinder its broader utilization in advanced engineering applications. This study introduces a novel technique to enhance sisal fibres tensile and thermal properties using chemical treatments, promoting sustainable composite uses. The Response Surface Methodology (RSM) was utilized to optimize the Sodium Hydroxide (NaOH) treatment parameters, resulting in a concentration of 7.66%, a temperature of 69.61 °C, and duration of 60.32 minutes. The outcomes were notable, including a tensile strength of 676.91 MPa, a cellulose content of 74.25%, and a remarkable reduction in water absorption to 47.94%. Secondary treatment utilized ammonium polyphosphate (APP) solutions at concentrations of 5, 10, and 15% (w/v) (designated as APP1, APP2, and APP3), which were prepared in 70% ethanol (v/v) to enhance penetration and achieve uniform coating. APP2 (10%) demonstrated optimal performance, enhancing tensile strength to 680 MPa and reducing water absorption to 37.56%. TGA results indicated that APP2 and APP3 maintained 80–90% of their mass at 300 °C, attributed to the formation of phosphorus-rich char which enhanced thermal stability. Scanning electron microscopy (SEM) and Fourier-transform infrared spectroscopy (FTIR) disclosed successful surface treatment, decreased hydrophilicity and enhanced fiber-matrix adhesion. The results presented here underscore the exciting potential of combining RSM-driven optimization with advanced surface modifications to create high-performance sisal fiber composites, perfect for the automotive and construction industries.
Vignesh et al. (Fri,) studied this question.