Microstructure and tensile properties of various varieties of rice husk

BACKGROUND: Rice husk is a complex hierarchical assembly of hollow fibers consisting of cellulose, hemicellulose and lignin. In addition, it can also contain pectin and significant amounts of silica. Rice husk can be used in diverse applications and generally in the form of rice husk powder. This study aimed to investigate the structural features and mechanical properties of various varieties of whole rice husks. RESULTS: Rice husk consists of three sections: epidermis, sub-hypodermis and hypodermis. The thickness of these layers, the diameters of the hollow fibers and the wall thickness vary with the variety of rice husk. The elastic modulus is typically between 0.3 and 2.6 GPa, and the ultimate tensile strength varies from 19 to 135 MPa depending on the variety of rice husk. CONCLUSION: Rice husk has a unique hierarchical structure in which the fibers exhibit a staggered perpendicular arrangement and the entire fiber sections are covered by an external shell. The tensile properties vary with the variety of rice husk. The wide range in these tensile properties may be attributed to the size and orientation of the fibers. © 2017 Society of Chemical Industry.