Poly(ethylene terephthalate) copolyesters and fibers modified with NPG and SIPE for improved hydrophilicity and dyeability

A series of Poly(ethylene terephthalate) (PET)-based copolyesters containing sodium-5-sulfo-bis-(hydroxyethyl)-isophthalate (SIPE) and 22-dimethyl-13-propanediol (NPG) were successfully synthesized. The results showed that the actual molar ratio of comonomers was consistent with the relative feed ratio, and the thermal properties of copolyester were greatly dependent on the amount of NPG. Meanwhile, the modified PET fibers were prepared via traditional melting-spinning and the effects of NPG amounts and draw ratio on the crystallinity, orientation, and mechanical property of the fibers were also investigated. Furthermore, the hydrophilic property and dyeability of the fibers were explored. The results showed that compared with the pure PET fibers, the resultant fibers exhibited improved hydrophilicity and dyeability, which also were controllable by tuning the amount of NPG and in turn provided the modified PET fibers with more potential application in various fields.