Microstructure design of polyester industrial yarns with excellent flame retardancy and high strength

In order to solve the problem that it is difficult to balance the high strength and flame retardancy of polyester industrial yarn, the possibility of controlling the uniform dispersion of flame retardant without affecting the crystallization of polyester was discussed in this paper. The long-chain branched flame retardant with good thermal stability in the range of processing temperature was chosen to blend with high viscosity polyester. The addition of flame retardant reduced the melt viscosity and the crystallization ability of polyester, so the melt spinning and drawing process of the flame retardant polyester industrial yarn were optimized for the sufficient crystallization of polyester based on the rheological and crystallization properties of flame retardant polyester. Due to the steric effect of flame retardant, it was eliminated from the crystal region and only existed in the amorphous region of polyester. As a result, the microstructure with high crystallinity and orientation and the morphology with a uniform dispersion of flame retardant were obtained. The flame retardant high strength polyester industrial yarn was successfully prepared with a limiting oxygen index of 32.0% and a breaking strength of 8.0 cN/dtex, which meets the UL-94 V-0 standard and shows good durability of flame retardant after washing and rubbing treatment, achieving the goal of flame retardancy and high strength for the polyester industrial yarn.