Isolation and characterization of cellulose nanocrystals from Saharan aloe vera cactus fibers

Abstract

Saharan aloe vera cactus leaves fibers (SACLFs) are a biodegradable and renewable agro textile fiber enriched with cellulose polysaccharides. The isolation of cellulose nanocrystals (CNCs) from SACLFs is an alternative approach to reinforcement for bio-composites applications. In this study, we show that standard chemical methods for the extraction of cellulose microfibrils and sulfuric acid hydrolysis (64 wt%) will result in usable CNCs. The resulting CNCs were characterized by XRD, FTIR, TGA and TEM. Fourier Transform Infrared Spectroscopy (FT-IR) confirms that the maximum amount of noncellulosic materials is removed from SACLFs. High yield content (32%) of CNCs is achieved by sulfuric acid hydrolysis and sonication process. It also enhances the crystalline size and crystallinity index of CNCs, which are confirmed by XRD. TEM analysis of CNCs shows a rod-like structure with diameter (10–14 nm), length (200–255 nm) and high aspect ratio of 18–20, which confers good reinforcing properties. These were tested in biodegradable agar film, whose tensile strength is increased by 27% when 5 wt% of CNCs from SACLFs was incorporated into the matrix. The SACLFs represent an interesting source of cellulosic reinforcing materials.