Study On The Structure And The Property Of The High Modulus Low Shrinkage Polyester Industrial Yarn

High modulus and low shrinkage polyester(HMLS PET) industrial yarns, as one of promising industrial yarns, can be used as tire corn yarns, rubber reinforcement materials and high-speed sewing threads. So it is significant to research the structure and the property of HMLS PET industrial yarns.First, to characterize the structure and the property of HMLS PET industrial yarns, the WAXD, sonic orientation, DSC, tensile and heat shrinkage experiments were carried out, and the results were also compared with the common PET filament yarns. The results indicate that HMLS PET industrial yarns display higher crystalline degree, larger crystalline region, and higher orientation degree. The modulus-strain curve of HMLS PET industrial yarns appears a low plateau during the strain range 2%-5%, while the common PET filament yarns do the same during a wider strain range, i.e. from 4% to 13%. The heat shrinkage of HMLS PET industrial yarns is much lower than that of common PET filament yarns.Second, the influences of twisting and heating on the mechanical properties of HMLS PET industrial yarns were studied by comparing with high-strength PET industrial yarns and PA industrial yarns. The results indicate that twisting has greater influences on mechanical properties of HMLS PET industrial yarns than those on high-strength PET industrial yarns and PA industrial yarns. When the number of twist is more than 300T/m, the mechanical properties of HMLS PET industrial yarns decreases dramatically. The heating has less effect on the mechanical properties of the three yarns under the heating range in our study.Finally, the PET industrial yarns were spun from high viscosity PET chips with 3 different spinning processes: UDY-DY, POY-DY and FDY process. The structure, mechanical properties and heat shrinkage of the fibers were measured. The results indicate the structure and properties of the fibers spun from UDY-DY process are inferior to those of HMLS PET fibers. The mechanical properties of the fiber spun by POY-DY process are improved, but the heat shrinkage rate is still great. The fibers spun by FDY process display better mechanical properties and better heat shrinkage than those of fibers spun by POY-DY process, but which are still inferior than those of HMLS PET yarns. Based on the above experiments results, the suggestion of improving mechanical properties and decreasing the heat shrinkage further of the fibers from FDY process are given.