Study Of PET Fibers Structure And Their Properties

PET (Polyethylene terephthalae) is a kind of popular textile materials. However, the macromolecule is lack of the functional groups which can react with the dyestuff directly. And PET with high degree of crystallinity and tight structure which can have hydrogen bond with disperse dye. So it is hard for the dye molecule to get inside the fiber. It means PET is difficult to dye. That is why it is with great sense of improving the PET fibers' dyeing behavior.There are many factors influencing the dyeing behavior of fibers and textile things. For fibers, firstly the factors are chemistry structure, mainly referring to chemical components, degree of polymerization, molecule stereo-structure ect.. Then macromolecule structure, mainly referring to degree of crystallinity , crystallite size, degree of orientation ,size of amorphous regions ,and size and distribution of the porosity ect.. In this paper, we used DSC, crystallization rate detector, polarizing microscope and DMTA to study the relationships between the dyeing behavior and degree of crystallinity, rate of crystallization, crystallite size, transition temperature in four sea-island fibers. The results showed low degree of crystallinity, slow rate of crystallization, large crystallite dimension and low transition temperature would benefit the improvement of PET fibers' dyeing behavior.The experiments used three physically blending modifier to enhance the dyeing behavior of PET.1.Using PC(Polycarbonate)/PEG(Polyethylene glycol) blending modifier to decrease the degree of crystallinity and transition temperature, and change the crystallite structure to enhance the dyeing behavior of PET. Through the experiments we found that the loading level of PC 0.4% and PEG 1% could enhance the visual color depth value above 2.5 order. Considering the results PC/PEG modified the spinnability and mechanical performance, after analysising the POY and DTY properties we found the above loading level could get the best combined properties.2. Using Clay /PEG blending modifier to change the crystallite structure of PET and decrease the degree of crystallinity to get the PET with better dyeing behavior. We found that the loading level of PEG 0.5% and Clay 1% could enhance the visual color depth value above 2.0 order. Considering the spinnability and mechanical performance, the best loading level is above that could get the best combined properties.3. Using Rare Earth/Clay blending modifier to decrease the degree of crystallinity to get better dyeability and low cost PET fibers with dye concentration. We found that the loading level of Clay 0.5 % and Rare Earth 0.25% could enhance the visual color depth value above 1.5 order. Considering the spinnability and mechanical performance, the best loading level is above that could get the best combined properties.