Characteristics And Classification Of Polyester Fibers: From Molecular Structure To Textile Technology

1. Distinguish with the naked eye. As consumers, when choosing fabric products, they often make a subjective evaluation of the fabric by touching it with their hands and looking at it. For example: Lun-spun silk has a bright luster, feels a little rough and hard, and has a clammy feeling. If you clench it tightly with your hands and then release it, it will have more wrinkles. There will still be traces after it is flattened. Pull out the cloth and moisten it with your tongue. It will be straight and easy to pull. Broken, broken, and have different elasticity when wet or dry. Polyester imitation cotton fabric.

It is not easy to wick away sweat, has a prickly feeling to the touch, and easily generates static electricity. However, cotton products have a soft, comfortable feel and are sweat-absorbent. There are many products. As a practitioner who is not engaged in textile inspection, it is difficult to distinguish various fibers by visual identification. Therefore, the naked eye identification method is only for reference. To further verify the fiber type, the following methods are needed.

2. Combustion method. The combustion method is the most common fiber identification method. Compared with chemical reagent testing, it is simpler and easier to perform. Compared with naked eye observation, it has higher identification, but the premise is that you must master the physical and chemical properties of common fibers. The burning properties of polyester are: close to the flame - softening, melting and shrinking, in the flame - melting, slow burning, colored flame, blue edge of the flame, black smoke from the top of the flame, open flame - continue to burn, sometimes stop burning And self-destruction. Burning odor ~ slightly aromatic or sweet. Characteristics of the residue - the ash is hard and black in the shape of a ball, difficult to crush with fingers.

3. Microscopic observation method. The cross-sectional shape of polyester is not very recognizable because it is very similar to other chemical fibers. The cross-sections are different depending on the spinning method. The longitudinal surface is generally smooth. However, the fibers that can be easily identified by microscopic observation are cotton fibers. Since cotton fibers are natural fibers with a waist-circular cross-section, cotton fibers can be easily distinguished through a microscope.

4. Chemical solvent method. Nylon will not dissolve when boiled in glacial acetic acid, while nylon will disappear.

5. Dyeing method. Polyester is not easy to dye, so you can choose targeted dyes and other fibers for comparison. Here we would like to explain the two reagents commonly used in fiber identification: No. 1 dye and iodine-potassium iodide reagent. The No. 1 dye dyes polyester in red, but the iodine-potassium iodide reagent does not dye it.

6. Infrared spectroscopy. The molecular composition of the fiber can be determined by measuring its chemical groups, and thus what kind of fiber it is.
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