Study on Structural and Morphological of Steam-Treated Sorghum Stalk Fiber: Enhancing Potential for Reinforcement in Polymer Composite

Abstract

Lignocellulosic biomass, such as sorghum stalk fiber, has received a lot of interest as reinforcement in polymer composites because of its renewable nature, low cost, and potential environmental benefits. This is due to crystalline cellulose fibrils embedded in hemicellulose, lignin, wax, and other impurities in the lignocellulosic fiber. As a result, treatment to remove non-cellulosic components, expose cellulose fibrils, and improve the adhesion with polymer matrices is critical for their usage as reinforcement in polymer composites. This study investigates the effects of environmentally friendly steam treatment on sorghum stalk fiber's structural and morphological properties. Sorghum stalk fiber was subjected to steam treatment conditions at different durations. Fourier transform infrared (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and sessile drop tests were used to examine the structural and morphological changes generated by steam treatment. It was observed that the steam treatment of sorghum fiber was successful in eliminating part of the amorphous lignin and hemicellulose components as well as contaminants such as wax, causing the crystallinity ratio to rise. Defibrillation also occurs, and the fiber surface becomes rougher. Due to the rough fiber surface and the space created by defibrillation, the polymer matrix can penetrate the fiber and increase its adhesion by a mechanical interlocking mechanism.