The Structure And Properties Of The Dyed Polyester Fibers

The polyester fibers have been rapidly developed in the world since it came out in 1942. With its output arranged first in all chemical fibers, it is widely used in various industries, currently its applications market has been largely occupied by the textile and clothing field. There is a phenomenon in the spinning process of the polyester fibers, compared with the white polyester fibers, the dyed(coffee color,gray, dark blue and black) polyester fibers wind around the rubber roller more seriously in the gilling step. So far, some related textile enterprises still have not found a method to solve this phenomenon. In order to find possible causes of the above phenomenon, the various modern test methods were used to investigate the structure and properties of the dyed and white polyester fibers, then compared and analyzed the results.Firstly, the morphology, molecular structure and aggregation structure of the dyed polyester fibers were tested by the modern testing methods, such as scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction analysis. The results showed that, the longitudinal morphology of the dyed polyester fibers was uniform, and some substance was obviously adhered to the surface of the dyed polyester fibers, also, the darker, the more adherent substances. In addition,dyeing did not have any effect on the molecular structure of the polyester fibers,because it did not bring in any new groups. And the molecular structure of polyester fibers was ethylene terephthalate. More over, the degree of crystallinity was high, the amorphous region between molecules was less,and the degree of crystallinity of dyed polyester fibers was slightly higher than that of the white polyester fibers.Secondly, the friction, wetting, moisture absorption, electrostatic and thermal properties of the dyed polyester fibers were tested. The results showed that, the coefficient of friction and friction of the dyed polyester fibers were slightly higher than that of the white polyester fibers, the water contact angle of the dyed polyester fibers were greater than that of the white polyester fibers, the moisture regain of the dyed polyester fibers were lower than that of the white polyester fibers, the quality of the specific resistance of the dyed polyester fibers were about 10 times higher than that of the white polyester fibers, and the internal thermal decomposition of the dyed polyester fibers were between 360 ~ 470?, in details, the rate of weight loss reached a maximum at about 433?, the glass transition temperature was about 90?, the crystallization temperature was about 254 ?, and the cross-linking reaction temperature was about 434?.Thirdly, the oligomer was extracted from the polyester fibers and wascharacterized, then the possible causes that the dyed polyester fibers wind around the rubber roller more seriously were analyzed. The results showed that, the content of the oligomer from the dyed polyester fibers were obviously higher than that of the white polyester fibers, and the darker, the more oligomer, and the surface substance(oligomer) was adhered to the fiber surface. The main component of the cyclic oligomer was similar to the terephthalate. In addition, the thermal stability of the oligomer extracted from the dyed polyester fibers was poorer than the fibers itself, in details, the rate of weight loss reached a maximum at about 343 ?, the glass transition temperature was about 115 ?, the crystallization temperature was about223 ?,the melting temperature was about 300 ?,and the cross-linking reaction temperature was about347?. More over, the oligomer from the dyed polyester fibers became sticky at 110 ? and could be firmly adhered to the yarn material under pressure. Above all, the above phenomenon may be related to the larger friction, the larger specific resistance, the larger water contact angle,and the more oligomer that easy became sticky under high temperature.