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Properties of silk materials
- May 30, 2018 -

Modern industrial silk, there are few 100 percent silk products, mainly natural fiber, artificial fiber, cellulose combination.

Natural fiber

Silk contains natural fiber are mainly silk fiber, is ripe secretion when silkworm cocoon silk is set into a continuous long fiber, also known as silk, is the human use of one of the earliest animal fiber, mulberry silk, tussah silk, castor silk, cassava, silk, etc.

Silk fiber is the only natural filament fiber that has been used in practice. Silk fiber because of silkworm feeding into a variety of different, including eat mulberry leaves form of mulberry silk fiber, food oak leaves formation of tussah silk fibers and the cassava leaf, mulberry leaf, castor leaves form other wild silk fibers. Mulberry silk fiber and tussah silk fiber can keep the form of long silk fiber in the long silk yarn formed by the cluster. In the long silk yarn formed by the collection of mulberry silk fiber and tussah silk fiber, the long silk yarn of mulberry silk fiber is the most important, accounting for the majority of the natural long silk yarn.

Structure of silk

Silkworms spit out two silk threads at the same time, but after solidification and forming, they will combine to form a cocoon silk. The section of cocoon silk resembles glasses. Each cocoon silk contains two silk fibers which are bonded together by silk glue. It has a cross-section feature close to a triangle, but the shape and cross-section size are not uniform.

Sericin, also known as sericin fiber, is the final use of silk fiber.

Sericin wrap around sericin fiber, its existence will have an important impact on the use of fiber, processing and product style.

The content of silk glue on each cocoon filament is not even, the silk that begins to spit out, the content of silk glue is low, the silk that exhales at the end, the content of silk glue is highest. Silk fiber has relatively perfect primary fiber structure, which can fully show the fine quality of natural fiber.

Chemical composition

Chemical composition of silk

Chemical composition of silk

The Fibroin. シ ル ク タ ン パ ク), also known as: silk fibroin. It is a kind of high molecular compound with nitrogen, and the single base of its macromolecular is prunus amino acid. The general formula of the structure of prunus l is RCH (NH2) COOH, which is called as amino acid because its amino is adjacent to carboxyl group or carboxylic acid. It can be seen from the structural general formula of silk fibroin molecules that, on the different peptide bases of the whole macromolecular chain, the connected side bases are different, which is an important feature of natural protein fibers.

Of a total of 18 kinds of amino acids of silk fibroin, accounts for about 70% of the silk fibroin protein content - 80%, including glycine (gly), alanine (ala) and serine (ser) accounted for about 80% of the total of the above.

modified

Silk fibroin has many excellent performance, but because of the silk fibroin molecules containing a certain amount of hydroxyl of phenol and other structure, easy to absorb ultraviolet light and degeneration, under uv irradiation, amino acid composition in cracking, whiteness dropped significantly, with the increase of irradiation time, the silk fibroin yellowing degree will increase, particularly in the presence of water, the yellow is more serious [2-3]. Mechanical properties and thermal performance drastically [4], also has a great influence on its performance, and silk fibroin and difficult to dyeing and easy to fade, etc, in order to make the defect improved, has to be modified, the modified method can use biology gene to improve silkworm varieties, also can use chemical and physical method is improved, usually in the form of chemical modification and polymer blending the two methods. [5]

Synthetic fiber

Artificial fiber is a kind of non-natural fiber obtained by physical and chemical method, which is divided into regenerated fiber and chemical fiber. Regenerated fiber is a kind of fibrous material made from some natural macromolecular compounds or their derivatives, which is then dissolved into a textile solution, and then sprayed with silk. Chemical fibers are synthetic fibers made from petroleum, natural gas, coal and agricultural by-products. Artificial fibers are added to the silk mainly to make the silk anti-wrinkle, anti-moth and more easily preserved.

Man made fibers are only 100 years old. Before that, man had relied on natural fibers such as cotton, wool, silk and hemp for textile, clothing and other production. Since the 1950s, various kinds of synthetic fibers have come out successively, with large quantity and low price, greatly enriching the total production and use range of textile fibers, and becoming the competition of natural fibers. Synthetic fiber raw material is oil, but 30-50 years after the earth's oil resources is dried up, along with the advancing of social economy and the change of consumer consciousness, in order to deal with the oil crisis and adapt to the globalization trend of environmental protection concept, fibre industry also gradually to the development and use of natural fibers. All kinds of new type fiber, such as natural CaiSeMian, bamboo fiber, Lyocell fiber, PLA fiber, soybean protein fiber, silkworm pupa protein fiber, etc., all has the characteristics of natural fiber, not only excellent performance and environmental protection.

features

advantages

First: wear comfortably. The real silk is made up of protein fiber, which has good biocompatibility with human body. Besides, its surface is smooth, and its friction and stimulation coefficient to human body is the lowest among all kinds of fiber, only 7.4%.

Second: good absorbance and dehumidification. Enrichment of fibroin fiber amino (CONH), hydrophilic groups such as amino group (NH2), and due to its porosity, easy water molecular diffusion, so it can absorb the moisture in the air or water, and keep a certain moisture. In normal temperature, it can help the skin retain a certain amount of moisture, not too dry skin; Wear in summer, but the sweat that can human body educates again and heat sends out quickly again, make a person feels cool and clinking.

Silk not only has good heat dissipation, but also has good heat preservation. Its insulation benefits from the structure of multi - pore fiber. There are many tiny fibers in silk fibers, and these tiny fibers are made up of even smaller fibers. Therefore, the solid silk is actually more than 38% hollow. There is a large amount of air in these gaps, which prevents the heat from escaping and makes the silk warm.

Third: sound absorption, dust absorption, flame retardant. Pure silk fabric has high void ratio, so it has good sound absorption and inhalation, so it can be used for interior decoration in addition to making clothes. Because silk has hygroscopic and dehumidifying properties as well as moisture retention, inhalation and porosity, it can also adjust indoor temperature and humidity, and can absorb harmful gases, dust and microbes. In addition, the thermal denaturation of silk fiber is small, more heat, heated to 100 ℃, only 5-8% embrittlement, while most of the synthetic fiber thermal alteration degrees to 4, 5 times larger than the pure silk. Silk of combustion temperature at 300-400 ℃, flame retardant fiber, and the synthetic fiber combustion temperature at 200-260 ℃, which are flammable, fusible. Accordingly, use silk fiber as the raw material of interior decoration, not only can have sound absorption, dust absorption, heat preservation function, still have fire retardant function.

Fourth: uv resistance. The tryptophan and tyrosine in silk protein can absorb ultraviolet ray, so silk has better anti-ultraviolet function. And ultraviolet ray is very harmful to human skin. Of course, after absorbing ultraviolet ray, silk itself can produce chemical change, make silk fabric in the sunlight irradiation, become yellow easily.

Fifth: health care. Silk fiber health care function is irreplaceable, and it contains 18 kinds of amino acids necessary to human body, is almost the same with human skin contains amino acids, so it have the laudatory title of "second skin" of human beings. Real silk clothes, not only can prevent uv radiation, defense and harmful gas leaking, resist harmful bacteria, but also can enhance the vitality of body surface skin cells, promote the metabolism of skin cells, at the same time for some skin disease has the good auxiliary therapeutic effect.

disadvantages

Easily wrinkled, easy to absorb, not strong enough, fast fading, can not keep warm.