Strength Properties of Surface Modified Kenyan Sisal Fibres

Abstract

This study aimed at determining and comparing the mechanical properties of natural, mercerized, and cornified sisal fibers. Sisal fiber morphology was modified by mercerization using a 0.06 Molar sodium hydroxide solution and by a seven-hour, seven cycle cornification at 100°C. The fiber strength properties were then determined and analyzed using the Weibull Cumulative Density Function. Mercerized sisal fibers displayed the most significant improvement in tensile strength with mean fracture stress of 271 MPa, which showed a 68.30% increase in tensile strength compared to untreated sisal fiber’s 161.02 MPa. Cornified sisal fibers had a mean fracture stress value of 198.57 MPa, which was a 23.32% increase compared to untreated sisal fibers. Untreated sisal fibers had the highest Weibull Modulus of 7.616. Mercerized and cornified sisal fibers had Weibull Moduli of 6.175 and 4.723, respectively. These results show that although fiber surface treatment leads to a significant improvement of Kenyan sisal fiber strength properties, the delignification associated with mercerization and the collapse of the lamella structure that accompanies cornification either exacerbated existing flaws or introduced new flaws in the fibers.

Keywords

• sisal fiber
• mercerize
• cornify
• fracture stress
• reference stress
• weibull