Synthesis And Properties Of Cationic Dye-dyeable Ptt Copolyester

As a newly polyester, Poly(trimethylene terephthalate) (PTT) has wide application prospects in clothing, carpets, non-woven fabric etc for its unique properties. However, there is no group that can form chemical or lonic bonds with dyes in the molecular chain of PTT, resulting in the PTT fibers only can be dyed with disperse dyes. Compared with cationic dyes, the using of disperse dyes has many disadvantages, such as the poor environmental effects, the incomplete of chromatography, not brilliant of the color and the huge investment in equipment, to a certain extent, limited the application of PTT in the fiber industries. In this paper, SIPP was synthesised, and then SIPP was used as third monomer, PBA and PEG were employed as forth monomer to synthesis a series of modified PTT by polycondensation. The compositions and structures of copolyesters were determined by 1H-NMR. Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) were used to analyze the thermal properties of copolyesters. The rheological properties and the non-isothermal crystallization behavior of copolyesters were detected by capillary rheometer and DSC, which could provide basic data for spinning or other processing of modified copolyesters.The synthesis conditions of SIPP were optimized, results showed that Ti(OBu)4 was a efficient catalyst and the amount of it was appropriate to 1000ppm, continuing to increase the amount of catalyst has little effect on the reaction rate. The best feeding ratio of 1,3-PDO and SIPM is 10.14:1. The reaction rate was faster and the product has good color when the reaction temperature was 173℃. The polycondensation reaction rate was accelerated with the rising of the reaction temperature, but the concentration of the end carboxyl was too high at the higher reaction temperature, the reaction temperature was controlled between 165 to 170℃as better. The introduction of the third monomer SIPP accelerated the condensation reaction rate, but the flowability of the melt was getting worse and it was harmful to the improvement of the product intrinsic viscosity, while the introduction of the fourth monomer PBA or PEG could improve the flowability of the melt. The analysis of the thermal properties showed that the Tg, Tc and Tm of PTT were 44.8℃, 68.9℃and 224.9℃correspondingly. With the increase of the third component, the Tg declined when a small amount of SIPP was introduced and then increased, Tc gradually increased, Tm decreased. With the increase of the PBA or PEG the Tg, Tc and Tm of the copolyesters were all gradually reduced. TGA results suggested that all modified copolyesters' thermo-gravimetric temperature were above 360℃, indicating that all modified copolyesters had good thermal stability, and could meet the requirements for further processing.Rheological behaviors analysis showed that PTT and its copolyesters were tipically non-Newton fluid, exhibiting shear thinning behavior in the investigated shear rate range, and the non-Newton index of them were all less than 1. The introduction of SIPP made the rheological properties of copolyesters become worse, while the introduction of PBA or PEG could improve the rheological properties of copolyesters, which was beneficial to the spinnability of copolyesters. The no-isothermal crystallization kinetics behaviors of PTT and its copolyesters were consistent with the Jeziorny equation, the Avrami exponent n of PTT were between 4.24 to 4.61, suggested a three-dimensional spherulite growth with homogenous nucleation mechanism. The Avrami exponent n of the modified copolyesters were approximately from 1.72 to 2.64, so we assumed that the crystallization mechanism of modified copolyesters was heterogeneous nucleation. The activation energy of modified copolyesters were abvious higher than PTT, suggesting that the crystallization rate of the copolyesters was more sensitive to the cooling rate. Therefore, it was of great importance to control the cooling rate in further processing.