Qualitative Analysis Of The Polyester Fibers Based On POM

This paper focus on experimental analysis of the fibers including PET, PTT, PBT and repreve PET fiber which could be easily mixed up in our regular fiber analysis and testing. First part of the paper described at length the systematical studies the common physical and chemical properties of the above fibers; and then the qualitative identification process between these fibers was investigated using polarized light microscopy (POM for short); at last, the influencing factors that might affect the recognization of certain fibers were experimantally discussed.Firstly, the the physical and chemical properties of polyester fibers were systematically studied using common but important fiber testing methods including the mechanical properties, DSC, TG, burning performance, solubility and solvent weightlessness test. The results show that:(1) the fracture strength of PET is larger than PTT and PBT, while repreve PET and PET performs similar fracture strength; the elongation at break of PTT is significantly higher than PET, PBT in the middle, while Repreve PET has significantly lower break elongation than PET.(2) According to the test results of the initial decomposition temperature and decomposition temperatures, PET fibers perform higher temperatures than PTT and PBT fibers, PTT performs similarly with PBT, and Repreve PET is similar with PET.(3) During the burning performance observation, it was found that although PET, PTT and PBT fibers show similar combustion behaviors, the smell (or the smoke) they produced in burning are different. However, Repreve PET and PET fibers present basically the same combustion behaviors and smell.(4) In the solubility test, PET performs higher stability than PTT and PBT fibers in all kinds of solvent; in addition, PTT is most sensitive to DMF among these fibers, and PBT is most sensitive in alkaline hypochlorite solvent. Repreve PET shows similar solubility with PET in the solvents.Secondly, qualitative analysis and recognication of polyester fibers using POM were implemented. Experimental results show that the most suitable operation parameters using POM for observation of polyester fibers are as following: magnificationis500X, polarizer angle is120°, and the angles between fiber longitudinal direction and the polarizer are+45°or-45°, with the compensating plate1λ. The experiments prove that each kind of polyester fibers, PET, PTT, PBT and Repreve PET fibers, present characteristic images under POM, thus they can be clearly distinguished from each other.Lastly, the factors that could influence the qualitative analysis of PET, PTT, PBT and Repreve PET were studied, including dyeing and finishing conditions, colors, lengthes and cross sections, etc. The results show that:(1) delustering agent appears as black spots in POM, it has no effect on qualitative analysis of polyesters using POM.(2) It’s suggested that a decolorization treatment of the colored polyesters before testing with POM could be much helpful for effective identification of the fibers.(3) The fiber fineness does not affect the qualitative analysis of PET using POM; however, the variance in distribution of colors across fiber width due to variance of fiber fineness shall be paid enough attention.(4) PET fibers with different shapes of cross section appear differently with the PET fibers with normal cross section shapes; but up to now, nearly all the polyester fibers with variant cross section shapes are PET fibers.(5) The images the same between different types of staple and filament PET.(6) The damages on the surface or body of fibers, do not affect the qualitative analysis of polyester fibers using POM.This work helped researchers to systematically learn about the characteristics of polyester fibers, offered valuable expeience to recognize between polyester fibers and, most importantly, provided theoretical data for qualitative analysis of polyester fibers by POM.