The evaluation of structure and properties of high-strength polyester industrial fibers with different polycondensation processes

Increasing the molecular weight via polycondensation process is an efficient way to improve polyester industrial fiber strength. This paper compares the performance and structures of poly(ethylene terephthalate) (PET) fibers made with solid-state polycondensation (SSP) and liquid-state polycondensation (LSP) processes. Two PET fibers were prepared by melt spinning with SSP and LSP. The structures of the fibers were characterized by wide-angle X-ray scattering (WAXS), small-angle X-ray scattering (SAXS), birefringence and dynamic mechanical analyzers (DMA). The PET fiber with SSP possesses a little larger molecular weight of narrower distribution, greater tenacity, higher crystallinity and orientation, larger lamellar thickness, smaller tilting angle and smaller amorphous layer thickness than that with LSP. The results indicated that although the differences in the molecular weight and its distribution of the fibers made with SSP and LSP are not notable, the microstructures and mechanical properties of the spun HT fibers are quite different.