| Polyethylene terephthalate(PET) fiber has the largest yield among the synthestic fibers in the world, widely used in many fields due to its excellent chemical and physical properties. However, PET industry is now facing excess production capacity, which forces manufacturers to develop multi-functional and differential.fibers. The modification of the dyeability and hygroscopicity of PET have always been mainly researched.In the modification of dyeability of PET, disperse easy dyable and cationic easy dyeable PET fibers have been mostly researched and have industrial products. However, anionic dyeable PET (ADP) has no commercial products except CERES POLYESTER produced by Japan in1972. APD fiber is a kind of new differential fiber with good prospects, because it could be dyed with wool and polyamide fiber together and the contained nitrogen could increase hygroscopic property of PET fiber.ADP was mostly prepared by blending with nitrogen-containing basic modifiers. In this paper, ADP was prepared by copolymerization, which benefited the dispersion of additives in polyester compared with blending. Due to the basic co-monomer should have surfficient thermal stability for not inducing PET degradation reaction, two kinds of monomers with good thermal stability were first synthesized, including the first-reported noval monomer contained imidazoline ring. The synthesis method was simple (with no solvents) and using the cheap and common raw materials.The first kind of monomer T6T was synthesized by dimethyl terephthalate (DMT) and1,6-hexanediamine (HDA), which fit for DMT method of PET. For PTA method of PET, another monomer EG-T6T was prepared by T6T and ethylene glycol (EG). The results of Fourier Transformed Infrared (FTIR) and1H-NMR indicated that T6T and EG-T6T were a mixture of oligomer amide with alternated structure.1H-NMR could acculate their average polymerization degree n. The n value of EG-T6T was lower than that of T6T, which meant amide could be substituted by EG in the ester exchange reaction. Differetial Scanning Calorimetry (DSC) results further demonstrated that T6T and EG-T6T were a mixture, with different melt points and crystalline temperature. Thermogravimetric Analysis (TGA) showed that they both had good thermal stability, suit for polyester polymerization.The second kind of monomer EAI was synthesized by DMT and diethylenetriamine (DETA). For PTA method of PET, another monomer EG-EAI was prepared by EAI and EG. The results of FTIR, Pyrolysis Gas Chromatography-Mass Spectrum (PyGC-MS) and13C-NMR (Inverted Gated Decoupling and DEPT135) indicated that EAI was a kind of ester-amide with imidazoline ring structure. The content of imidazoline could be acculated from13C-NMR. DSC results showed EAI was amorphous substance with no crystalline temperature and clear melt points, which further demonstrated that the structure of EAI was complicated. TGA showed that EAI also had good thermal stability, suit for polyester polymerization.The copolyester contained different nitrogen contents were respectively prepared by EG-T6T and EG-EAI, with PTA and EG. The polymerization paremeters of copolyester were different from that of pure PET. Copolymerizing polyester with amide could cause nitrogen loss, which might be attributed to the amide substitution by EG in the ester exchange reaction and the heat-related amine degradation. The discharging continuity and spinnability of copolyester were similar with pure PET. DSC results indicated that crystallization process of copolyester was retarted. TGA showed that the two kinds of copolyester both had good thermal stability as pure PET. The hygroscopicity and acid-dyeability of polyester were improved to some extent by co-polymerizated with these two kinds of amide monomers. |
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