Physical Properties & Applications of Silk

The unique elegance, beauty, and luxury of silk clothing make people talk about it. With the development of science and technology, other superior qualities of silk are gradually being recognized by people. This article will introduce the characteristics of silk’s moisture absorption and release properties, heat preservation, biological adaptability, flame resistance and heat resistance, etc., and discuss its unique physical properties and its development and application prospects.

Moisture absorption and desorption

Natural fibers have good hygienic properties due to their good moisture absorption properties. Under the experimental conditions of 20 °C and a relative humidity of 65%, the moisture absorption rates of several fibers are: wool 16%, silk 11%, cotton 8%, viscose 13%, nylon 4%, and polyester 0.4%. It can be seen that silk has good moisture absorption properties. Although wool and cotton have good hygroscopicity, they are not as good as silk. Once sweating, the sweat cannot quickly evaporate through the clothing, so that the pores of the wet clothing fabric are filled with moisture. The thermal conductivity of water is higher than that of the fabric fibers, and greater than the thermal conductivity of air, leading to the insulation of the clothing. Decreased sex, and the skin feels sticky and uncomfortable. Because of the rapid release of moisture from silk fabrics, the moisture can drain to the outside world in a short time, and it feels comfortable to wear. If you wear silk knit underwear next to your body, then wear cotton knit clothing outside, so that it is both moisture permeable and moisture absorbing, not only wearing warm and comfortable, but also beneficial to human health and health.

Heat preservation

In the complex heat exchange process between people, clothing, and the environment, clothing is located between the human skin and the environment, and it has both heat resistance and heat conduction effects. The thermal conductivity of clothing shows how fast the human body dissipates heat to the surrounding environment. The lower the thermal conductivity of clothing (that is, the slower the thermal conductivity), the higher its thermal insulation performance or thermal insulation performance. The thermal conductivity of various clothing materials is represented by the thermal conductivity λ, which can be detected by a thermal conductivity meter. The main principle is to sandwich the sample between the heating copper plate and the heat-absorbing copper plate, measure the heat supply Q required to maintain a certain temperature difference ΔT, and then obtain the thermal conductivity λ according to the following formula

In the formula: I——- heater current; R——— heater resistance; J—conversion factor; d—fabric thickness; A—heat transfer area.

The thermal conductivity of air is very low, so still air is the best thermal insulator. For fiber clothing materials of the same thickness, the more static air contained in the fiber structure, the lower the thermal conductivity, and the better the thermal insulation performance, that is, the thermal insulation performance. Both silk and wool are porous fibers. Compared with other fibers, the air content is higher, and they have excellent thermal insulation properties, making them good materials for warm clothing.

Biocompatibility

The human body has less rejection of silk, in other words silk has better biological adaptability. Medically, the characteristics of silk are processed into surgical sutures and ligatures, which not only have high strength and low friction coefficient, but also have good elasticity and effective connection. In addition, the seric polypeptides in silk have a significant effect on healing skin wounds. Tests show that skin care products containing seric polypeptide have a good effect on the symptoms of skin cracks and chapped skin.

Flame and heat resistance

From the perspective of viscoelasticity, the thermal denaturation of the fiber is found, and it is found that the silk fiber has 5%~8% embrittlement at 100 ℃, 10%~15% embrittlement at 150 ℃, even when the temperature reaches 200 ℃. 30% embrittlement, and the thermal denaturation of synthetic fibers can reach 4 to 5 times that of silk. The burning temperature of silk is about 300 ℃ ~ 400 ℃, which is a flame-retardant fiber, while the burning temperature of synthetic fiber is mostly 200 ℃ ~ 250 ℃, which is easy to melt and burn, and it will also produce harmful gases. Therefore, when wearing silk clothing, when exposed to open flames or high temperatures, it will not burn and scald the skin as easily as synthetic fibers. Using silk to make interior decoration materials, such as curtains, wall coverings, carpets, etc., not only has good thermal insulation, can save energy, and can also play a role in preventing fires.

In summary, silk has superior physical properties in terms of moisture absorption and moisture release, heat preservation, biocompatibility, flame resistance and heat resistance. The application range of silk and its products is very broad. With the development of science and technology, more properties will be discovered. We must make full use of silk, an excellent natural resource, to make greater contributions to people’s lives and the development of human society.