Imitation Cotton Copolyesters Of Synthesis And Preparation Of Fiber

Polyethylene terephthalate (PET) is a kind of widely-used synthetic polymer because of its excellent physical, chemical and mechanical properties. The strength of PET fiber is great, so it is feeling hard. The development trend of functional fiber is differential fiber, such as soft fiber. The soft fiber can be used as high quality textiles and thick textiles.The research on the modified PET was made in this thesis. With the third additive SIPE and the fourth additive polyethylene glycol (PEG), This thesis synthesized different multi-component polyester choosing the proper reaction conditions. The structure and properties of samples were characterized by means of differential scanning calorimetry(DSC), thermalgravity analysis(TGA), 1HNMR spectroscopy, Fourier transform infra-red spectroscopy (FTIR), X-ray diffraction(XRD) and Axial compression bening test of single fiber. The results were as follows:1.By FT-IR analysis, there were several major feature peaks showed. The proportion of SIPE and PEG in polymer is the same with the propotion of SIPE and PEG by NMR. Conclusions showed:The modified PET was prepared successfully through normal crafts.2. The glass transition temperature (Tg) and the cold crystallization temperature(Tcc) both reduced with the increase of PEG content and molecular weight. The same trend with Tg and Tcc, melting point of modified polyester was lower than that of pure PET.3. It was found that the Jeziorny model provided a satisfactorily good fit to the experimental data for these polyesters. At different heating rates, there were similar non-isothermal crystallization curves. Cold crystallization peak temperature was increased as the heating rate increased. Crystallization kinetics constant(Zc) was aslo increased, which showed cold crystallization rate was accelerated. The avrami exponent(n)was aslo increased, which showed the cold crystallization of copolyester is homegeneous nucleation.4. The results of TGA showed:With the third additive SIPE and the fourth additive PEG, The apparent activation energy reduced with the weight increase of PEG, which showed the comonomers had effect on the thermal stability of copolyester.5. The orientation degree of pure PET was the highest. The orientation index decreased as the PEG content and molecular weight increased. The fiber modulus showed the same trend with the orientation degree. Since PEG was introduced, the crystallinity of polyester fiber reduced and the grain increased, which increased the flexibility of the amorphous molecules. This structure would help to improve the flexibility of fiber.6. There was a quantitative method for characterising the soft of copolyester fiber. Measuring the equivalent bening modulus of the fibers through single fiber axial compression bending test, and then bending stiffness was calculated. Thus the bending stiffness indirectly charactered the soft of the fibers. Conclusions were:the equivalent bending modulus and bending stiffness were maximum, which means the fiber flexibility was the most worst, The bending stiffness of 4# (1% SIPE and 5% PEG) was the smallest, which means the fiber flexibility was the best.