Optimising Linear Density and Twist Factor for Enhanced Mechanical Properties of Jute Yarn/Bio-Epoxy Composites

This paper investigates the effect of the twist factor on composites made from jute yarns with different linear densities (193, 213, and 251 tex) twisted at four different levels (1460, 2420, 2820, and 3056 turns per meter x √tex). The results indicate that the composite made from the highest-density yarn required a lower twist factor to achieve the best mechanical properties. Specifically, the yarn with a linear density of 251 tex, twisted with a twist factor of 1460, exhibited the best mechanical properties with a tensile strength of 147.07 MPa, a modulus of elasticity of 13.7 GPa, and 1.36% elongation at break, at a volume fraction of 42%. In comparison, yarns with lower densities of 193 tex and 213 tex required a higher twist factor of 2420 to achieve their maximum properties. However, they demonstrated lower tensile strengths (122.49 MPa and 117.85 MPa), slightly lower moduli of elasticity (13.01 GPa and 11.67 GPa), and similar elongations at break (1.22% and 1.28%), at higher volume fractions (43% and 44%), respectively. The tensile properties of the composite show that higher strength was not achieved at the same optimum twist factor for the yarn’s highest tenacity. Yarn made of 193 tex has the highest tenacity when twisted with 3056 (turns/m√tex), 213 tex at 2420 (turns/m√tex), and 251 tex at 2420(turns/m√tex), indicating that the impact of the twist factor can have different effects on yarn and its resulting composites. The analysis underscores the importance of balancing twist factor and yarn linear density for high-performance composites. It indicates that a low twist factor is necessary to keep the fibres parallel to the yarn axis and arrange them in the best direction for load-carrying capacity. The results indicate that the effect of the twist factor is linked to yarn linear density, addressing the ongoing challenge of balancing these two parameters for optimal composite performance.