(1) Visual inspection method
This method is the most simple and convenient, and does not require any detection equipment, but requires the identification personnel to have rich practical experience. When identifying textile fabrics, first carefully remove several yarns from the material, untwist the yarns, and then identify them according to the shape, color, feel, elongation, strength and other characteristics of the fibers. Such as: cotton fiber feels very soft, hemp fiber feels rough and rough, wool fiber feels smooth and elastic, chemical fiber feels smooth and stiff; cellulose fiber, cotton, linen, wool fiber, etc. are short fibers, while silk fibers It is a long fiber with a special luster. The luster of chemical fiber is very good, and sometimes even has a special light, but it is not as soft as silk; The wet strength of rubber fibers is very low, while the strength of synthetic fibers such as polyester and nylon is high, the elongation ability is large, and the recovery ability after elongation is also large. To sum up, we can make a preliminary identification of fibers according to the above differences.
Although the hand-feeling visual inspection method is simple, it requires rich practical experience and cannot identify specific varieties of chemical fibers, so it has certain limitations.
(2) Combustion method
Combustion method is one of the simple and commonly used methods to identify fibers. It uses the difference in the characteristics that various fibers show to the outside when they are burned to identify fiber types. When identifying, firstly use tweezers to hold a small bundle of fibers or yarns, move them slowly close to the flame, and carefully observe the burning speed, smoke density of the fibers when they are close to the flame, in the flame and after they leave the flame. The difference in characteristics such as color and ash after combustion, and these characteristics are recorded, and the fiber combustion characteristics table in Table 3-1 can be compared to roughly identify which type of fiber the fiber belongs to. The combustion method also has its application limitations. It is only suitable for pure textiles or interwoven products, but is not very suitable for blended products, core-spun yarn products and products that have undergone fire protection treatment, and the accuracy of the results is relatively low.
(3) Microscope observation method
Because different fibers have different appearance, cross-section and longitudinal morphology, the morphology of the fibers can be observed and identified by ordinary biological microscopes (for small structures, electron microscopes can be used to observe and identify). This method can be used for pure spun, blended and interwoven products, but for synthetic fibers, it can only determine their general categories, but not their specific varieties. With the development of the chemical fiber industry, there are more and more imitation natural fibers, and the imitation is more realistic, to the extent that it can be faked, which will increase the difficulty in the application of this identification method.
(4) Chemical dissolution method
Different fibers have different degrees of dissolution in different solvents and different concentrations. The dissolution method is to use the solubility of fibers in chemical solvents to identify fiber types. This method is suitable for all kinds of fibers and all kinds of products.
When identifying, for pure textiles, as long as a certain concentration of solvent is injected into the test tube containing the fibers to be identified, the dissolution conditions (dissolved, partially dissolved, slightly soluble, insoluble) are observed and carefully distinguished, and the dissolution temperature is carefully recorded. (Dissolve at room temperature, dissolve by heating, dissolve by boiling). For blended fabrics, the fabrics need to be decomposed into fibers, then placed on a concave glass slide, dissolved with a solution, and observed under a microscope to observe the dissolution of the two fibers to determine the fiber type. Since the concentration and temperature of the solvent have obvious effects on the dissolving properties of fibers, the concentration and temperature of the solvent should be strictly controlled when identifying fibers by the dissolving method.
(5) Drug coloring method
Identify fibers according to the difference in the coloring properties of various fibers to different dyes. This method is only applicable to undyed products. Commonly used colorants are divided into general-purpose and special-purpose two types. General-purpose colorants are mixed with various dyes, which can color various fibers, and then identify the fiber type according to the color; while special colorants are used to identify a specific type of fiber. A commonly used colorant is an iodine-potassium iodide solution. When using colorants to identify fibers, the dyes and auxiliaries on the fabric should be removed before coloring, so as not to affect the identification results.
