Study On The Structure And Properties Of Poly (Ethyleneterephthalate-co-sodium-5-sulfo-isophthalate-co-2-methyl-1, 3-propanediol) Copolyester And Fiber

Recently, the research and development of the synthetic fibers have entered a new stage in developed countries. The new synthetic fibers are developed with high comfortable properties. As we known, the most representative monomer with cationic group incorporated into the polymerization reaction of polyethylene terephalate (PET) was studied, and this kind of monomer is sodiosulfo isophthalate (Na-SIPA) or its ester such as Na-SIPE or Na-SIPM (for short, SIP). The properties of fibers and textiles were greatly improved with the application of this kind of copolyester. The content of SIP in this kind of copolyester normally is 1.5 mol%, and this copolyester is called CDP. The content of the SIP monomer needs to be increased to explore the further properties of the CDP. However, it is difficult for the melt to flow because of steric hindrance from SIP, which is disadvantageous to later processing. In this thesis, a series of Poly(ethyleneterephthalate-co-sodium-5-sulfo- isophthalate- co-2-methyl-1,3-propanediol) copolyesters were synthesized with SIP (3 mol% of dibasic acid), terephthalic acid (PTA), ethylene glycol (EG) and 2-methyl-1,3- propanediol (0～15mol% of diols). The properties of this copolyesters (MCDP) and fibers were studied, including thermal properties, crystallization properties, rheology properties and dyeing properties and so on.The composition and structure of MCDP were investigated by element analysis method , FIR and ~1H-NMR. Due to electronegativeness and boiling point of 2-methyl-1,3-propanediol (MPD), the content of MPD unit incorporated into the polymer was always more than that fed before polymerization.The crystallization, melt behavior and thermal steady properties of MCDP with different content of MPD were investigated by using DSC, DMA and TGA. At the same time, The result showed that T_g and thermal steady property declined a little with the increasing content of MPD.The crystallization properties of the copolyester were studied by DSC as well as X-ray diffraction. The result showed that the integrity of copolyesters was also broken, leading to the decreasing of crystallization, decline of crystallinity and the minishing of crystal size.The study on rheology properties of MCDP copolyesters showed that the copolyesters were non-Newtonian flow the same as HCDP. Viscous flow activation energy of MCDP was lower than that of HCDP, which meant the decline of sensibility to the temperature. Moreover, the non-Newtonian index n increased with the rising content of MPD in the copolyesters, tending to act as Newtonian flow.MCDP copolyesters had good spinnability. MCDP fibers had acceptable mechanical properties though it was a bit lower than HCDP’s. With the increasing content of MPD, MCDP fibers had higher flexibility and resilience. What’s more, the fibers had better moisture absorption and dyeing properties.