Preparation Of Pet-Based Imitation Cotton Copolyester Fibers And Their Structure And Properties

Polyethylene terephthalate (PET) is a kind of synthetic fiber which has Jhe largest production, and has many excellent properties such as high fracture strength and high modulus, heat-set, good resistance to heat and light, good resistance to organic solvents and oxidants, good corrosion resistance, so it is widely used. However, due to its high macromolecular chain regularity and crystallinity, its molecule has no strong polar groups, which affect the surface of the hydrophilic fibers. Therefore, many researchers has paid attention to modification of the PET fibers, and the third component a sulfonic acid group is introduced to improve their dyeing properties, and the fourth component polyethylene glycol (PEG) and the fifth component1,2-PDO can improve elasticity, softness, lower melting point, improving the hygroscopicity, antistatic property and so on.Based on these, this thesis synthesized different multi-component polyester choosing the proper reaction conditions with the third monomer SIPE, the fourth monomer PEG and the fifth monomer1,2-PDO. The structure and properties of the synthesized samples were characterized by NMR spectroscopy, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetry analysis (TGA). Four copolyester samples whose comprehensive properties are relatively better than other samples were selected to be spun, and the corresponding fiber properties of mechanical property, moisture regain and warmth property, and structures of orientation, crystallizationwere were characterized. The results were as followed.1. The FT-IR results showed that there were several major feature peaks showed on the spectrogram. The proportions of the third monomer SIPE, the fourth monomer PEG and the fifth monomer1,2-PDO in polymer are almost the same as those of SIPE, PEG and1,2-PDO by NMR spectroscopy.2. The DSC results showed that the glass transition temperature (Tg) and the cold crystallization temperature (Tcc) reduced with the increase of1,2-PDO content. As the similar trend to Tg and Tcc, the melting point T,,, of all the samples was lower than that of pure PET. The TGA results showed that the introduction of the fourth monomer PEG and the fifth monomer1,2-PDO weakened the thermal stability of copolyester with the third monomer SIPE.3. The tensile strength, initial modulus, orientation and crystalline of the fiber were decreased and the elongation at break rose with the increase of1,2-PDO content as the PEG content kept constant. With the flexible PEG and1,2-PDO introduced, the grain increased and the crystallinity of polyester fiber reduced, which increased the flexibility of the amorphous molecules. This structure would help to improve the flexibility of fibers. Due to the introduce of PEG and1,2-PDO, the moisture regain and the warmth index Qmax of the modified fibers were higher than PET fibers and with the increase of1,2-PDO content, the moisture regain and warmth index Qmax were boosted.