Abstract: Based on the trial spinning of polyester/cotton (75/25) and polyamide/cotton (75/25) blended yarns with high-tenacity polyester fiber, high-tenacity polyamide fiber and cotton, the paper analyzed the spinning process and related technical parameters and decided the optimum properties of the blended yarn. By testing the critical twist of the ply yarn result from the optimal blended single yarn, it draws the conclusion that the tenacity reaches the maximum when the twist of the polyester/cotton ply yarn and the polyamide/cotton ply yarn is at 850 twists/m and 900 twists/m respectively.

Key words: high-tenacity polyester fiber; high-tenacity polyamide fiber; blending; spinning process; critical twist