With the continuous progress of textile production technology, more and more new fibers become the raw materials of textiles, which brings the problem of identification of textile fibers. The commonly used fiber identification methods include microscopic observation, combustion, reagent color, dyeing, dissolution and so on.

1. Microscope observation method

The longitudinal film and cross-sectional sections of the fibers were made, and the longitudinal and transverse morphology of the fibers were observed under the microscope, and the fibers were identified according to the differences in morphological characteristics, as shown in Table 1.

Two, combustion method

In the combustion process of different fibers, flame, smoke, odor, residue, etc., are different. Therefore, fiber types can be distinguished according to the characteristics of fiber during and after combustion, as shown in Table 2.

Third, reagent color method

Because of the different structure of all kinds of fibers and the different coloring reactions to iodine and potassium iodide solution, the fibers can be identified by observing the color and swelling of the fibers after the action of reagents. This identification only applies to white fibers, and colored fibers can be tested only after fading. Reagent preparation: Dissolve 20 grams of iodine in 100 ml of saturated potassium iodide solution, and then soak the fiber for 1 minute, and then judge according to its color after full washing, as shown in Table 3.

Fourth, the dyeing method

The dyeing method is used to identify fibers, mainly by using the different reactions of various fibers to dyes. There are two kinds of dyeing methods: cold dyeing and boiling dyeing. The formula of the dyeing method is shown in Table 4.

Table 4 Formula of dyeing method

Pour the recipe in Table 4 into 50ml ethanol and stir until dissolved, then dilute with distilled water to 500ml and set aside. Cold dyeing method directly put the fiber into the solution, and then rinse the fiber with cold water, extrude the water, and observe the color for identification; Boiling dyeing method put the fiber into the solution for dyeing, boiled for 3 minutes, rinsed 3 times, and then put it into 0.1% Yijia Piao T solution for rinsing, extruding water, and observing the color for identification. The dyeing reactions of various fibers are shown in Table 5.

Table 5 Dyeing reactions of various fibers

5. Dissolution method

The dissolution method is the most effective method to identify various fibers, and the principle is to use the dissolution characteristics of various fibers in different chemical solvents and at different temperatures to determine their varieties.

The fiber to be identified can be placed in a test tube, injected with a solvent, stirred with a glass rod, and the dissolution of the fiber can be observed. If the amount of fiber is very small, the sample can also be placed in a concave surface with a concave slide drop solvent, cover the slide, and directly under the microscope. In the identification of fibers by dissolution method, the concentration of solvents and heating temperature should be strictly controlled, and attention should be paid to the dissolution rate of fibers. The use of dissolution method requires accurate understanding of the chemical characteristics of various fibers, and the inspection procedure is also complicated. The use of microscope observation and combustion method is more intuitive, but the inspector must have rich practical experience; Reagent color method, dyeing method operation is more complex, can be used in special circumstances.