Determination of fiber definition and composition by analytical methods in wool-PET yarn blends

The fiber description in the yarn composites is made with TS 4739 standard and/or analytical instruments; and the quantitative determination of the mixtures is made with the methods which specified in TS 1700, TS 4785 and TS EN ISO 1833 standards. After the publication of the TS EN ISO 1833 standard series, TS 1700 and TS 4785 have lost the update. Since the TS EN ISO 1833 standard series is prepared to include both standards, comparisons are made with this series.New analysis methods are needed to be developed due to the high cost and long process of current methods, the need for the specialized labor force, the low reproducibility between laboratories and the detrimental effects on the environment and human health of chemicals which are used. In this thesis, an environmentally friendly, fast and low-cost Differential scanning calorimetry (DSC) based analytical method has been developed to identify fibers and determine fiber compositions of wool-polyester (PET) blended yarns and fabrics.In this study, firstly TS EN ISO 1833 standard was explained; the general principles of this method, the experimental setups used in quantitative fiber analysis, the steps of quantitative analysis method are explained. TS EN ISO 1833-4 standard, which describes the method of quantitative analysis of binary fiber mixtures containing wool, was then described. The problems and obstacles experienced during the application of the test method according to this standard were stated. In particular, the preparation of the sodium hypochlorite solution and the difficulty in controlling the active chlorine content were addressed.In this study, 2,8 dtex black dyed combed wool fibers and 1,44 Den polyester (PET) fibers were used. Wool and PET fibers were conditioned for 24 hours in a laboratory environment to provide standard moisture content.DSC, Fourier Transform Infrared (FT-IR) and Thermal Gravimetric Analysis (TGA) instruments were used to test the determination of wool-PET fiber composition ratios by analytical methods. First, suitable test specimens for these devices have been prepared.For the DSC study, 35 samples of wool-polyester blends were prepared. These samples contain polyester fiber in 3% increments from 0% to 100%. To increase the accuracy of the work, the second set of samples was prepared at the same rate and the total number of samples was increased to 70. From the thermograms obtained from the DSC, the water output enthalpy of wool was calculated at the first heating, while the melting enthalpy of the PET was calculated at the second heating. In the first heating step, the output enthalpy of the water near 100°C was examined and the ratio between the change in this energy and the amount of wool was established. Because the wool contains 18% moisture and does not contain moisture in the PET structure, the water output only occurs in wool and the water output increase was observed as the amount of wool in the sample increases. Wool is a fiber that directly decomposes without melting, so the enthalpy change observed near 250°C in the second heating is due to melting of PET fiber. The ratio between this enthalpy change and the amount of PET was established.A linear relationship between the wool and polyester fiber ratios were found at the end of the DSC study and the relationship was formulated. In order to reduce the uncertainty of the side effects of the different DSCs in these formulations, the indium reference material melt enthalpy correction was used as the coefficient. For control, 3 different samples of wool-polyester ratio were analyzed by DSC and wool water output and PET melting enthalpies were determined. The fiber ratios were determined by entering these values into the formed formulas. The same samples were sent to 3 independent laboratories and subjected to fiber ratio analysis according to TS ISO EN 1833-4. The results of the laboratory and DSC methods were compared with the statistical evaluation, and the results showed 96% similarity in the 95% confidence interval. Thus, the newly developed method proved to be accurate, reliable and accurate.It was predicted that the developed method can be used in determining other fiber composition ratios such as cotton-PET, viscose-PET by working with more samples and different mixtures.Analyses were also conducted to see if a similar work could be done with other analytical instruments, FT-IR and TGA. 11 wool-PET blend samples containing PET fiber with 10% increments for FT-IR and 5 wool-PET blend samples containing PET fiber with approximately 20% increments for TGA were used. It was observed in FT-IR spectra that the peaks changed as the fiber composition ratios changed. Through the presence and absence of the peaks, comments on the fiber description in the composition could be made, but no information was available to make a quantitative analysis. In the FT-IR measurements, inconsistencies were observed in the spectra as the fiber distribution in the sample was not homogeneous. How the fiber distribution at the corresponding portion of the ATR is, the device gave its spectrum and did not give the spectrum of the general mixture. For this reason, no study for quantitative analysis according to FT-IR data was made. In TGA study, it was concluded that the ratio change was difficult to calculate from the mass change. There was no regression analysis between the changes in the fibers and the fiber ratios in the composition, so no study on quantitative analysis with TGA was made. It has been found that the use of both FT-IR and TGA analyses in quantitative analysis of fiber composition is not appropriate. As a result, it has been observed that it is more efficient to use faster, simpler and more reliable analytical method such as DSC ​when using complex and long-standing classical methods for determining fiber quality and quantity. It is also aimed to increase the test reproducibility using this method. Unlike the conventional analytical method, which takes 2 days, preparation of the sample and loading of the device takes a maximum of 1,5 hours with the analysis time of the device. This new method saves time and labor​, and since no chemicals are used, the problem of chemical consumption, environmental and health damage or chemical disposal has been removed.