Mechanical Properties of Varieties of Kenaf (Hibiscus Cannnabinus) Stem
Due to the diversity in the use of kenaf, its processing and production, there is need to determine some mechanical properties of the kenaf stem so as to get a suitable database for design and mechanical features of the equipment and facilities for processing kenaf stem. This study was designed to investigate the effect of moisture content (mc) on mechanical properties of kenaf stems. Five common varieties of kenaf in Nigeria were identified and selected (Ife Ken 400, Ife ken D1 400, NHC 25 v 31, NHC 1 v 37 and Kuba 108). Samples were stored at room temperature for five weeks and moisture loss was monitored. Samples from each variety were cut into 30mm were prepared and placed horizontally between the crosshead of the Instron Testing Machine (Model 3369, 100KN, USA) to determine the mechanical properties (load at maximum tensile stress, tensile strain at maximum tensile stress, energy at maximum tensile stress and tensile stress at break) at 2mm/min. The data were subjected to statistical analysis. Highest load at maximum tensile stress of 714.90 at 21% mc and the least load at maximum tensile stress of 406.44 at 18% mc were obtained respectively for Ife Ken D1 400 and Ife Ken 400. Highest energy at maximum tensile stress (2.6466) was obtained for Kuba 108 while Ife Ken 400 has the least energy at maximum tensile stress (0.7865). Ife Ken D1 400 has the highest tensile stress at break (22.336) while Ife Ken 400 has the least Tensile Stress at break (8.567). Moisture content had significant effect on the mechanical properties of the kenaf stem. The study established that the kenaf stem is harder and may be difficult to crush for extraction of fibre at higher moisture content.
