Variation of Engineering Properties of Kenaf Fiber with Maturity Day

The paper presents the influence of growth on the properties of kenaf fiber for optimal harvest time for superior performance relevant to sustainable material applications. Kenaf's physical and mechanical properties during different maturity stages are underexplored. A randomized block design with five replications was utilized. Fiber samples were collected at 80–130 days after planting. Water-retting techniques were used for fiber extraction. The fiber diameter initially increases from 80 days to a peak, then gradually declines (from 23.67 to 58.16 µm). The tensile strength of kenaf fibers exhibits notable fluctuations from 80 to 90 days, stabilizing after 100 days with slight increases and decreases until 130 days. The strength ranged from 3719 to 918 MPa. The fiber elastic modulus exhibited a similar trend to tensile strength, with values ranging from 228 to 51 GPa. The density generally appears to be increasing marginally, with pronounced fluctuations. Likewise, the percentage elongation's variation is within a minimum and maximum band, showing a sinusoidal nature with a marginal increase as days of maturity increase. The study established that kenaf fibers achieve optimal mechanical performance between 100–110 days of maturity, emphasizing maturity stage as a key determinant of fiber quality.