There are two major characteristics of fiber: first, it is too thin to be observed directly by the naked eye, and its diameter is generally between several microns and dozens of microns or finer; second, its length diameter ratio can reach infinity in tens of millions to tens of thousands or even in theory, which is related to the type of fiber, which makes the fiber obviously show long properties in mechanics, such as small-scale partial deformation in bending and torsion, and overall pulling Even in the elastic range, it shows considerable deformation. So simply speaking, the fiber is a kind of thin and long, that is, the diameter is too thin to be observed directly by the naked eye, and the ratio of its length to diameter is more than dozens of times.
Natural fiber
Natural fibers exist in nature and can be obtained directly. According to their sources, they can be divided into plant fibers, animal fibers and mineral fibers.
（1） Plant fiber
Plant fiber is obtained from seeds, fruits, stems, leaves and other parts of plants, which is natural cellulose fiber. Fibers from plant phloem, such as flax, jute, Apocynum, etc.; fibers from plant leaves, such as sisal, banana, etc. The main chemical component of plant fiber is cellulose, so it is also called cellulose fiber.
Plant fiber includes seed fiber, phloem fiber, leaf fiber and fruit fiber.
Seed fiber: refers to the single-cell fiber formed by epidermal cells of some plant seeds. Such as cotton and kapok.
Phloem fiber: a single fiber or process fiber obtained from the phloem of some plants. Such as: flax, ramie, jute, bamboo fiber.
Leaf fiber: it is the technological fiber obtained from the leaves or sheath of some plants. For example: sisal, banana hemp.
Fruit fiber: fiber obtained from the fruit of some plants. Such as: coconut fiber.
Animal fiber
Animal fiber is obtained from the hair of animals or gland secretion of insects. The fibers from animal hair are wool, rabbit hair, camel hair, goat hair, yak hair, etc.; the fibers from animal gland secretion are silk, etc. The main chemical component of animal fiber is protein, so it is also called protein fiber.
Animal fiber (natural protein fiber) includes hair fiber and gland fiber.
Hair fiber: a fiber with multicellular structure composed of keratin in the growth of animal hair follicles. Such as: sheep hair, cashmere, camel hair, rabbit hair, mohair.
Silk fiber: a fiber produced by the silk glands of some insects, especially by the larvae of Lepidoptera, and also by the secretions of some mollusks. Such as: silk.
Mineral fiber: it is the fiber obtained from fibrous mineral rock. Its main components are various oxides, such as silica, alumina, magnesium oxide, etc. its main sources are all kinds of asbestos, such as chrysotile, crocidolite, etc.
Chemical fiber
Chemical fiber is a kind of fiber processed by chemical treatment. It can be divided into man-made fiber (regenerated fiber), synthetic fiber and inorganic fiber.
Man made fiber is also called regenerated fiber.
Man made fiber is a kind of textile fiber which is made of materials containing natural fiber or protein fiber, such as wood, sugarcane, reed, soybean protein fiber and other fiber materials which have lost the value of textile processing. Mainly used for textile man-made fibers are: viscose fiber, acetate fiber, copper ammonia fiber.
Regenerated fiber refers to the fiber made by highly purified slurry made of natural polymers, such as regenerated cellulose fiber, regenerated protein fiber, regenerated starch fiber and regenerated synthetic fiber.
Synthetic fiber
The chemical composition of synthetic fiber is completely different from that of natural fiber. It is made from some substances that do not contain cellulose or protein, such as oil, coal, natural gas, limestone or agricultural by-products. The synthetic unit is first synthesized, and then the fiber is made by chemical synthesis and mechanical processing. Such as polyester fiber (polyester), polyamide fiber (nylon or nylon), polyvinyl alcohol fiber (vinylon), polyacrylonitrile fiber (acrylic), polypropylene fiber (polypropylene), polyvinyl chloride fiber (chlorine fiber), etc.
Inorganic fiber
Inorganic fiber is made of natural inorganic or carbon containing polymer fiber by artificial spinning or direct carbonization. Including glass fiber, metal fiber and carbon fiber.
